Tag: GLSI

Release – Greenwich LifeSciences Announces Approval to Expand FLAMINGO-01 into the United Kingdom

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Greenwich LifeSciences

Research News and Market Data on GLSI

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July 22, 2026 6:00am EDT

STAFFORD, Texas, July 22, 2026 (GLOBE NEWSWIRE) — Greenwich LifeSciences, Inc. (Nasdaq: GLSI) (the “Company”), a clinical-stage biopharmaceutical company focused on its Phase III clinical trial, FLAMINGO-01, which is evaluating GLSI-100, an immunotherapy to prevent breast cancer recurrences, today announced the regulatory approval to expand FLAMINGO-01 into the United Kingdom.

The Company’s application to expand FLAMINGO-01 into the UK has been formally approved by UK regulators, thus adding potentially 5-10 geographically distributed UK sites to the approximately 170-180 approved sites in the US and Europe.

The Company is collaborating with The Royal Marsden, a leading cancer research institute. Working with The Royal Marsden, we have been in discussions with many academic sites located in the following cities: London (multiple sites), Cambridge, Edinburgh, Oxford, Manchester, Southhampton, Cardiff, and potentially other cities. With regulatory approval, these start-up discussions will now move forward. The principal investigator at Royal Marsden, who will be serving as the UK national principal investigator, also plans to join the Steering Committee.

CEO Snehal Patel commented, “We are very excited to be adding these UK sites from prominent research institutions. The initial introduction was driven by patient interest in the UK. Our hard work with The Royal Marsden in submitting our regulatory application has now paid off with our regulatory approval. The UK population of 70 million is one of the largest populations in Europe and we look forward to offering participation in FLAMINGO-01 to these patients.”

The Royal Marsden opened in 1851 as the world’s first hospital dedicated to cancer diagnosis, treatment, research and education. Today it operates as a specialist cancer centre. Together with its principal academic partner, The Institute of Cancer Research, London, The Royal Marsden is designated as the UK’s only National Institute for Health and Care Research (NIHR) Biomedical Research Centre (BRC) dedicated solely to cancer. The Royal Marsden and The Institute of Cancer Research (ICR) are recognised as one of the top four comprehensive cancer centres in the world for the impact of their research, influencing cancer treatment and care for all cancer patients. As a centre of excellence, they pioneer the very latest in cancer treatments and technologies, as well as leading the way in innovative cancer diagnosis and education.

Based on 2019 and 2021-2022 data from Cancer Research UK, there are approximately 59,400 new breast cancer cases in the UK every year. Breast cancer is the most common cancer in females, which is 30% of all new female cancer cases.

About FLAMINGO-01 Open Label Phase III Data

More than 1,500 patients have been screened at a screen rate of approximately 600-800 patients per year. The 250 patient non-HLA-A*02 arm is now fully enrolled, where all patients received GLSI-100, which is 5 times more treated patients and recurrence rate data than the approximately 50 patients treated in the Phase IIb trial. The Primary Immunization Series (PIS), which includes the first 6 GLSI-100 injections over the first 6 months and is required to reach peak protection, is followed by 5 booster injections given every 6 months to prolong the immune response, thereby providing longer-term protection.

  • In the non-HLA-A*02 arm, a preliminary analysis of recurrence rates after the PIS is completed shows an approximately 70-80% reduction in recurrence rate.
  • The non-HLA-A*02 arm is trending similarly to the Phase IIb trial results and hazard ratio where HLA-A*02 patients were treated and where breast cancer recurrences were reduced up to 80% compared to a 20-50% reduction in recurrence rate by other approved products.
  • The immune response at baseline prior to any GLSI-100 treatment, the increasing immune response during the PIS, and the safety profile of non-HLA-A*02 patients is trending similarly to the HLA-A*02 arms of FLAMINGO-01 and to the Phase IIb study. 
    • The AACR Meeting 2026 delayed-type-hypersensitivity (DTH) poster and the ASCO Meeting 2026 injection site reaction (ISR) poster can be seen and downloaded at the bottom of the Phase III clinical trial tab on the Company’s website here.
    • As shown in both posters the frequency of DTH and ISR reactions increased statistically significantly over time.
    • As reported in Table 1 of each poster, each HLA-A type exhibited more frequent immune reactivity after treatment with GLSI-100 than at baseline.
    • Baseline DTH reaction prior to any treatment suggests that GP2 may be a natural antigen and that GP2 specific T cells may exist in some patients prior to any treatment with GLSI-100. Baseline immune response to GP2 prior to any vaccination with GP2 was also observed in the Phase IIb trial and is being observed in the blinded randomized arms of FLAMINGO-01, where HLA-A*02 only patients are being vaccinated.

Analysis of the open label data from FLAMINGO-01 has been conducted in a manner that maintains the study blind. The open label recurrence rate, immune response, and safety data is based on the patients enrolled to date in FLAMINGO-01 and the data provided by the clinical sites so far, which is not completed or fully reviewed, and is thus preliminary. While comparing any preliminary FLAMINGO-01 data to the Phase IIb clinical trial data may be possible, these preliminary results are not a prediction of future results, and the results at the end of the study may differ.

About GLSI-100 Phase IIb Study

In the prospective, randomized, single-blinded, placebo-controlled, multi-center (16 sites led by MD Anderson Cancer Center) Phase IIb clinical trial of HLA-A*02 breast cancer patients, 46 HER2/neu 3+ over-expressor patients were treated with GLSI-100, and 50 placebo patients were treated with GM-CSF alone. After 5 years of follow-up, there was an 80% or greater reduction in cancer recurrences in the HER2/neu 3+ patients who were treated with GLSI-100, followed, and remained disease free over the first 6 months, which we believe is the time required to reach peak immunity and thus maximum efficacy and protection. The Phase IIb posters and results can be summarized as follows and can be seen here:

  • 80% or greater reduction in metastatic breast cancer recurrence rate over 5 years of follow-up with a peak immune response at 6 months and well-tolerated safety profile.
  • The PIS elicited a potent immune response as measured by local skin tests and immunological assays.

About FLAMINGO-01 and GLSI-100

FLAMINGO-01 (NCT05232916) is a Phase III clinical trial designed to evaluate the safety and efficacy of Fast Track designated GLSI-100 (GP2 + GM-CSF) in HER2 positive breast cancer patients who had residual disease or high-risk pathologic complete response at surgery and who have completed both neoadjuvant and postoperative adjuvant trastuzumab based treatment. The trial is led by Baylor College of Medicine and currently includes US and European clinical sites from university-based hospitals and academic and cooperative networks with plans to open up to 170-180 sites globally.

For more information on FLAMINGO-01, please visit the Company’s website here and clinicaltrials.gov here. Contact information and an interactive map of the majority of participating clinical sites can be viewed under the “Contacts and Locations” section. Please note that the interactive map is not viewable on mobile screens. Related questions and participation interest can be emailed to: [email protected]

About Breast Cancer and HER2/neu Positivity

One in eight U.S. women will develop invasive breast cancer over her lifetime. In the US and Europe, there are approximately 700,000 new breast cancer patients per year and 9.5 million breast cancer survivors. HER2 (human epidermal growth factor receptor 2) protein is a cell surface receptor protein that is expressed in a variety of common cancers, including in 75% of breast cancers at low (1+), intermediate (2+), and high (3+ or over-expressor) levels.

About Greenwich LifeSciences, Inc.

Greenwich LifeSciences is a clinical-stage biopharmaceutical company focused on the development of GP2, an immunotherapy to prevent breast cancer recurrences in patients who have previously undergone surgery. GP2 is a 9 amino acid transmembrane peptide of the HER2 protein, a cell surface receptor protein that is expressed in a variety of common cancers, including expression in 75% of breast cancers at low (1+), intermediate (2+), and high (3+ or over-expressor) levels. Greenwich LifeSciences has commenced a Phase III clinical trial, FLAMINGO-01. For more information on Greenwich LifeSciences, please visit the Company’s website at www.greenwichlifesciences.com and follow the Company’s Twitter at https://twitter.com/GreenwichLS.

Forward-Looking Statement Disclaimer

Statements in this press release contain “forward-looking statements” that are subject to substantial risks and uncertainties. All statements, other than statements of historical fact, contained in this press release are forward-looking statements. Forward-looking statements contained in this press release may be identified by the use of words such as “anticipate,” “believe,” “contemplate,” “could,” “estimate,” “expect,” “intend,” “seek,” “may,” “might,” “plan,” “potential,” “predict,” “project,” “target,” “aim,” “should,” “will,” “would,” or the negative of these words or other similar expressions, although not all forward-looking statements contain these words. Forward-looking statements are based on Greenwich LifeSciences Inc.’s current expectations and are subject to inherent uncertainties, risks and assumptions that are difficult to predict, including statements regarding the intended use of net proceeds from the public offering; consequently, actual results may differ materially from those expressed or implied by such forward-looking statements. Further, certain forward-looking statements are based on assumptions as to future events that may not prove to be accurate. These and other risks and uncertainties are described more fully in the section entitled “Risk Factors” in Greenwich LifeSciences’ Annual Report on the most recent Form 10-K for the year ended December 31, 2025, and other periodic reports filed with the Securities and Exchange Commission. Forward-looking statements contained in this announcement are made as of this date, and Greenwich LifeSciences, Inc. undertakes no duty to update such information except as required under applicable law.

Company Contact
Snehal Patel
Investor Relations
Office: (832) 819-3232
Email: [email protected]

Investor & Public Relations Contact for Greenwich LifeSciences
Dave Gentry
RedChip Companies Inc.
Office: 1-800-RED CHIP (733 2447)
Email: [email protected]

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Source: Greenwich LifeSciences, Inc.

Released July 22, 2026

Greenwich LifeSciences, Inc. (GLSI) – Modifications To Phase 3 FLAMINGO-01 Trial Raise Probability Of Success

Posted on by [email protected]


Tuesday, July 21, 2026

Robert LeBoyer, Senior Vice President, Equity Research Analyst, Biotechnology, Noble Capital Markets, Inc.

Refer to the full report for the price target, fundamental analysis, and rating.

Trial Modifications Announced. Greenwich Pharmaceuticals announced modifications to the Phase 3 FLAMINGO-01 trial testing GLS-100 for the prevention of recurrent breast cancer. Several changes reflect preliminary findings and allow for increased enrollment in the pivotal arm of the trial. We believe the changes increase the likelihood of positive results in the interim and the final analyses, as well as potentially doubling the market.

The Original Phase 3 Design. The original trial design screened patients for HLA type, an immune system classification. Patients with HLA-A*02, the most common type, were randomized into two double-blind arms testing GLSI-100 against a placebo control. The non-HLA-A*02 patients were entered into an open-label arm. Following the standard of care treatment for breast cancer, patients were given six monthly doses of GLSI-100, then boosters every 6 months for 11 total doses.


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Release – Greenwich LifeSciences Provides Clinical Updates on FLAMINGO-01

Posted on by [email protected]
Greenwich LifeSciences

Research News and Market Data on GLSI

 Download as PDF July 20, 2026 6:00am EDT

STAFFORD, Texas, July 20, 2026 (GLOBE NEWSWIRE) — Greenwich LifeSciences, Inc. (Nasdaq: GLSI) (the “Company”), a clinical-stage biopharmaceutical company focused on its Phase III clinical trial, FLAMINGO-01, which is evaluating GLSI-100, an immunotherapy to prevent breast cancer recurrences, today provided the following clinical updates on FLAMINGO-01.

FLAMINGO-01 Data Safety Monitoring Board (DSMB)

The FLAMINGO-01 DSMB met in May 2026 and recommended the study continue as is without modification.

FLAMINGO-01 Steering Committee Clinical Strategy

On December 22, 2025, the company announced the following objectives:

“The Steering Committee also met at SABCS 2025 and discussed the clinical strategy, endorsing the planned modifications to FLAMINGO-01. The planned modifications subject to regulatory approval include:

  • increasing the size of the study, which would increase the power of the study thus decreasing the risk by designing the study to assume more recurrences even though fewer recurrences may be anticipated and observed,
  • doubling or quadrupling the enrollment rate, which will increase the patient years in the study more rapidly thus proportionately increase the event rate, which may shorten the time to reach an interim analysis or milestone,
  • continuing to enroll past the interim analyses so that the current momentum at the clinical sites continues,
  • using the interim analysis to potentially resize the study or to change the subsequent interim analysis, to change the number of events triggering an analysis, or to change the timing of the study based on recommendations by an independent committee, and
  • using a recently manufactured GP2 commercial drug product lot in FLAMINGO-01″

CEO Snehal Patel commented, “We are pleased to announce that following review by FDA and EMA regulatory authorities that these objectives have been met and that FLAMINGO-01 now has the hallmarks of a large pharma Phase III clinical trial. The study is now designed and sized to improve the probability of success, to attract the interest of sophisticated investors and pharma companies, and to maximize the chances that the Company could file a BLA after interim analysis 1, after interim analysis 2, or after the end of the study.”

Mr. Patel further added, “The transition is now underway globally at all sites. We have provided below in this press release the details of the study design reviewed by both the US and EU agencies, and currently subject to review by the UK and Canada, and will be updating the Company website and presentation, www.ClinicalTrials.gov, and videos accordingly. These agencies may provide additional recommendations or requirements at any time and we remain flexible to accommodate their advice as needed.”

The Company plans to now leverage the increased enrollment rate resulting from the combination of all HLA types together with the following: 1) the very high interest from patients and clinicians which has led to almost 200 clinical trial sites in the US and Europe, 2) the clinical operational capability in place 3) the currently trending low event rate, and 4) the efficient cost structure and burn rate that the Company has successfully funded through small capital raises.

Enrollment Rate into the Blinded Arm

As previously disclosed, all European and US Sites will combine all new patients independent of HLA type in the randomized arms of FLAMINGO-01. Non-HLA-A*02 patients who represent about 55% of the population and were on waiting lists for up to a year are now eligible for enrollment, which could provide for the rapid enrollment of up to 300 patients. This protocol amendment will more than double the enrollment rate increasing it by 122% or resulting in a 2.22x faster enrollment rate (55%/45% = 122%), which proportionately increases the event rate. This more than doubling of the event rate, provides an opportunity to derisk the study and provide multiple pathways to filing a BLA in the US with much higher probabilities of success at each opportunity for analysis.

Leveraging the High Interest from Patients and Clinicians

The Company has achieved a major milestone by screening over 1,500 patients in Flamingo-01, continuing its screening rate of approximately 150-200 patients per quarter or the equivalent of 600-800 patients per year in approximately 170-180 sites.

The 11 participating countries include: US, Spain, France, Germany, Italy, Poland, Romania, Ireland, Portugal, Belgium, and Austria. The Company is planning to add the following additional European countries due to interest from principal investigators and patients: Norway, Denmark, and Sweden in addition to the UK and Canada.

Rationale to Keep Enrollment Open Until Interim Analyses

In the double-blinded arms of the Phase III trial, the originally designed 500 HLA-A*02 patients were likely to be filled before the interim analysis and thus the clinical sites would have had to stop enrolling. If the interim analysis suggested that more patients should be enrolled, restarting enrollment would have been very difficult. A 2.22x increase in the enrollment rate without any other modifications would have accelerated the stopping of enrollment, but the probability of a successful data analysis at the interim analysis and the filing of BLA would not be increased. It isn’t in the study’s best interest to wait for more events without the option to continue enrolling to increase the event rate. It is optimal to keep enrolling while collecting events because even patients in the study for only a short time are at risk of recurrence and can add information to analyses.

Capital Raising Strategy Has Kept up with Modestly Increasing Burn Rate

The cash burn will be manageable as in the past due to the efficiently run and internalized clinical operations. The manufacturing of GP2 vials for the Phase III clinical trial has been completed with sufficient vials to treat all patients. Most of the start-up costs for the clinical sites have been paid. Many patients have entered the booster phase with 2 vaccinations per year with lower costs thus offsetting the higher costs for patients entering the study, when 6 vaccinations in the first 6 months during the primary immunization series are required.

The Company’s annual burn rate was approximately $7 million in 2024 and 2023 and $10 million in 2025. The income statements for these periods have been reported as much higher losses, but the cash flow used for operations is much lower due to the non-cash stock and options expenses added to the income statements.

For the second quarter of 2026, the burn rate is expected to be approximately $2 million versus a $4.7 million burn rate in the first quarter of 2026, leading to a Q2 2026 cash balance of approximately $8.9 million as of June 30, 2026 and an expected burn rate of $2-4 million per quarter going forward. The above preliminary financial figures are unaudited and are subject to change following completion of the Company’s financial review for Q2 2026. This capital raising strategy may provide a bridge to non-dilutive funding, such as strategic/licensing partnerships or debt/royalty financing vehicles, that would further fund FLAMINGO-01 and potential commercial launch activities.

Improved Trial Design Allows for Substantial Reduction in Risk

In the double-blinded arms of the Phase III trial, the trial has been designed to detect a hazard ratio (HR) of 0.55 in invasive breast cancer-free survival, where 28 events will be required for the 1st interim analysis, 56 events will be required for the 2nd interim analysis, and 133 events will be required to end the study. Interim analyses for superiority and futility will be conducted and, if successful, could lead to the filing of a BLA in the US at those times. The number of patients enrolled in the study will depend on the event rate and thus enrollment may continue for as long as necessary up to a maximum of 2,000 patients. This sample size provides 80% power if the annual rate of events in placebo-treated subjects is 2.4% or greater and the HR is 0.55. In addition, the number of events may be adapted by the DSMB based on interim analyses.

By doubling the number of events to trigger an interim and increasing the HR, which is offset by the more than doubling event rate due to the higher enrollment rate, and may or may not alter time lines, the probability of a positive study outcome can be increased substantially. An increase of the HR puts FLAMINGO-01 more in line with other prominent large pharma breast cancer Phase III clinical trials such as Katherine for Kadcyla and Destiny Breast-05 for Enhertu. The HR is equal to one minus the percent reduction in events caused by the treatment arm. For example, an HR = 0.3 would suggest a 70% reduction in events and an HR = 0.75 would suggest a 25% reduction in events by the treatment arm.

The Katherine study which compared Kadcyla to Herceptin breast cancer treatment in the adjuvant setting after surgery in the residual disease population assumed a design HR = 0.75 but realized a lower study result HR at the first interim of 0.5, which led to a sufficiently low p value and strong enough statistical significance to warrant approval for Kadcyla in the adjuvant setting following submission of interim data to the FDA. Approximately 1,486 patients were enrolled, 256 events were observed at the interim analysis, and 385 events were observed at the final analysis.

The Destiny Breast-05 study which compared Enhertu to Kadcyla breast cancer treatment in the adjuvant setting after surgery, in a higher risk residual disease population than Katherine, assumed a design HR = 0.675 but realized a lower study result HR at the first interim of 0.5, which led to a sufficiently low p value and strong enough statistical significance to warrant approval for Enhertu in the adjuvant setting following submission of interim data to the FDA. Approximately 1,635 patients were enrolled and 153 events were observed at the interim analysis.

GLSI-100 by contrast has shown a study result HR = 0.2 in the Phase IIb clinical trial for HLA-A*02 patients. In the 250 patient non-HLA-A*02 open label arm of FLAMINGO-01, which is now fully enrolled and where all patients received GLSI-100, a preliminary analysis of recurrence rates after the PIS is completed shows an approximately 70-80% reduction in recurrence rate or a HR = 0.2-0.3 when calculated by various methods. This data is early and will continue to mature over time. This low event rate is supported by immune response data that was recently published at AACR and ASCO conferences in 2026. The section below, “About FLAMINGO-01 Open Label Phase III Data”, summarizes these results and provides links to the posters at the conferences.

By increasing the original FLAMINGO-01 trial design HR = 0.3 to a design HR = 0.55 and by doubling the events required to trigger the first interim analysis from 14 to 28 events, the probability of success or power at the first interim analysis, if a lower study result HR = 0.3 is realized, increases from less than 20% to more than 85%. This increase in power at the first interim, when the study result HR is lower than the design HR, is possible due to the combination of both HLA types, while the more than double event rate at 2.22x offsets the doubling of the events required to trigger this first interim analysis. Effectively increasing the probability of filing a BLA at the first interim analysis from 20% to 85% justifies the study design changes.

Additional benefits of the new design include:

  • The first interim results may affect or alter the design of the second interim.
  • Endpoints can be analyzed by individual HLA types as well as one combined group of all HLA types and given that each patient has 2 HLA-A alleles, one from each parent, there are multiple analyses that can be conducted.
  • Doubling the market for GLSI-100 to potentially $10 billion in revenue per year by accelerating the clinical development of the non-HLA-A*02 population.
  • Capital raise requirements are still modest, based on the Company’s disciplined operations and low burn rate.

About FLAMINGO-01 Open Label Phase III Data

More than 1,500 patients have been screened at a screen rate of approximately 600-800 patients per year. The 250 patient non-HLA-A*02 arm is now fully enrolled, where all patients received GLSI-100, which is 5 times more treated patients and recurrence rate data than the approximately 50 patients treated in the Phase IIb trial. The Primary Immunization Series (PIS), which includes the first 6 GLSI-100 injections over the first 6 months and is required to reach peak protection, is followed by 5 booster injections given every 6 months to prolong the immune response, thereby providing longer-term protection.

  • In the non-HLA-A*02 arm, a preliminary analysis of recurrence rates after the PIS is completed shows an approximately 70-80% reduction in recurrence rate.
  • The non-HLA-A*02 arm is trending similarly to the Phase IIb trial results and hazard ratio where HLA-A*02 patients were treated and where breast cancer recurrences were reduced up to 80% compared to a 20-50% reduction in recurrence rate by other approved products.
  • The immune response at baseline prior to any GLSI-100 treatment, the increasing immune response during the PIS, and the safety profile of non-HLA-A*02 patients is trending similarly to the HLA-A*02 arms of FLAMINGO-01 and to the Phase IIb study. 
    • The AACR Meeting 2026 delayed-type-hypersensitivity (DTH) poster and the ASCO Meeting 2026 injection site reaction (ISR) poster can be seen and downloaded at the bottom of the Phase III clinical trial tab on the Company’s website here.
    • As shown in both posters the frequency of DTH and ISR reactions increased statistically significantly over time.
    • As reported in Table 1 of each poster, each HLA-A type exhibited more frequent immune reactivity after treatment with GLSI-100 than at baseline.
    • Baseline DTH reaction prior to any treatment suggests that GP2 may be a natural antigen and that GP2 specific T cells may exist in some patients prior to any treatment with GLSI-100. Baseline immune response to GP2 prior to any vaccination with GP2 was also observed in the Phase IIb trial and is being observed in the blinded randomized arms of FLAMINGO-01, where HLA-A*02 only patients are being vaccinated.

Analysis of the open label data from FLAMINGO-01 has been conducted in a manner that maintains the study blind. The open label recurrence rate, immune response, and safety data is based on the patients enrolled to date in FLAMINGO-01 and the data provided by the clinical sites so far, which is not completed or fully reviewed, and is thus preliminary. While comparing any preliminary FLAMINGO-01 data to the Phase IIb clinical trial data may be possible, these preliminary results are not a prediction of future results, and the results at the end of the study may differ.

About GLSI-100 Phase IIb Study

In the prospective, randomized, single-blinded, placebo-controlled, multi-center (16 sites led by MD Anderson Cancer Center) Phase IIb clinical trial of HLA-A*02 breast cancer patients, 46 HER2/neu 3+ over-expressor patients were treated with GLSI-100, and 50 placebo patients were treated with GM-CSF alone. After 5 years of follow-up, there was an 80% or greater reduction in cancer recurrences in the HER2/neu 3+ patients who were treated with GLSI-100, followed, and remained disease free over the first 6 months, which we believe is the time required to reach peak immunity and thus maximum efficacy and protection. The Phase IIb posters and results can be summarized as follows and can be seen here:

  • 80% or greater reduction in metastatic breast cancer recurrence rate over 5 years of follow-up with a peak immune response at 6 months and well-tolerated safety profile.
  • The PIS elicited a potent immune response as measured by local skin tests and immunological assays.

About FLAMINGO-01 and GLSI-100

FLAMINGO-01 (NCT05232916) is a Phase III clinical trial designed to evaluate the safety and efficacy of Fast Track designated GLSI-100 (GP2 + GM-CSF) in HER2 positive breast cancer patients who had residual disease or high-risk pathologic complete response at surgery and who have completed both neoadjuvant and postoperative adjuvant trastuzumab based treatment. The trial is led by Baylor College of Medicine and currently includes US and European clinical sites from university-based hospitals and academic and cooperative networks with plans to open up to 170-180 sites globally.

For more information on FLAMINGO-01, please visit the Company’s website here and clinicaltrials.gov here. Contact information and an interactive map of the majority of participating clinical sites can be viewed under the “Contacts and Locations” section. Please note that the interactive map is not viewable on mobile screens. Related questions and participation interest can be emailed to: [email protected]

About Breast Cancer and HER2/neu Positivity

One in eight U.S. women will develop invasive breast cancer over her lifetime. In the US and Europe, there are approximately 700,000 new breast cancer patients per year and 9.5 million breast cancer survivors. HER2 (human epidermal growth factor receptor 2) protein is a cell surface receptor protein that is expressed in a variety of common cancers, including in 75% of breast cancers at low (1+), intermediate (2+), and high (3+ or over-expressor) levels.

About Greenwich LifeSciences, Inc.

Greenwich LifeSciences is a clinical-stage biopharmaceutical company focused on the development of GP2, an immunotherapy to prevent breast cancer recurrences in patients who have previously undergone surgery. GP2 is a 9 amino acid transmembrane peptide of the HER2 protein, a cell surface receptor protein that is expressed in a variety of common cancers, including expression in 75% of breast cancers at low (1+), intermediate (2+), and high (3+ or over-expressor) levels. Greenwich LifeSciences has commenced a Phase III clinical trial, FLAMINGO-01. For more information on Greenwich LifeSciences, please visit the Company’s website at www.greenwichlifesciences.com and follow the Company’s Twitter at https://twitter.com/GreenwichLS.

Forward-Looking Statement Disclaimer

Statements in this press release contain “forward-looking statements” that are subject to substantial risks and uncertainties. All statements, other than statements of historical fact, contained in this press release are forward-looking statements. Forward-looking statements contained in this press release may be identified by the use of words such as “anticipate,” “believe,” “contemplate,” “could,” “estimate,” “expect,” “intend,” “seek,” “may,” “might,” “plan,” “potential,” “predict,” “project,” “target,” “aim,” “should,” “will,” “would,” or the negative of these words or other similar expressions, although not all forward-looking statements contain these words. Forward-looking statements are based on Greenwich LifeSciences Inc.’s current expectations and are subject to inherent uncertainties, risks and assumptions that are difficult to predict, including statements regarding the intended use of net proceeds from the public offering; consequently, actual results may differ materially from those expressed or implied by such forward-looking statements. Further, certain forward-looking statements are based on assumptions as to future events that may not prove to be accurate. These and other risks and uncertainties are described more fully in the section entitled “Risk Factors” in Greenwich LifeSciences’ Annual Report on the most recent Form 10-K for the year ended December 31, 2025, and other periodic reports filed with the Securities and Exchange Commission. Forward-looking statements contained in this announcement are made as of this date, and Greenwich LifeSciences, Inc. undertakes no duty to update such information except as required under applicable law.

Company Contact
Snehal Patel
Investor Relations
Office: (832) 819-3232
Email: [email protected]

Investor & Public Relations Contact for Greenwich LifeSciences
Dave Gentry
RedChip Companies Inc.
Office: 1-800-RED CHIP (733 2447)
Email: [email protected]

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Source: Greenwich LifeSciences, Inc.

Released July 20, 2026

Release – Greenwich LifeSciences Announces European Approval for Combining Both HLA Populations in FLAMINGO-01

Posted on by [email protected]
Greenwich LifeSciences

Research News and Market Data on GLSI

 Download as PDF

July 16, 2026 7:30am EDT

STAFFORD, Texas, July 16, 2026 (GLOBE NEWSWIRE) — Greenwich LifeSciences, Inc. (Nasdaq: GLSI) (the “Company”), a clinical-stage biopharmaceutical company focused on its Phase III clinical trial, FLAMINGO-01, which is evaluating GLSI-100, an immunotherapy to prevent breast cancer recurrences, today provided the following update on the combination of both HLA-A*02 and non-HLA-A*02 patients in FLAMINGO-01 in Europe.

All European and US Sites to Combine All Patients Independent of HLA Type in the Randomized Arms of FLAMINGO-01

The Company previously announced that US clinical sites started enrolling both HLA-A*02 and non-HLA-A*02 patients in the same randomized arms in FLAMINGO-01, based on the FDA’s review of such protocol changes, effectively more than doubling the enrollment rate of the pivotal arm of the study. Non-HLA-A*02patients who represent about 55% of the population and were on waiting lists for up to a year are now eligible for enrollment.

The European Medicines Agency (EMA) has completed their review and will also allow the combination of both HLA-A*02 and non-HLA-A*02 patients in Europe. Thus, all 170-180 clinical sites in the US and Europe, are now operating under the same protocol and could continue enrolling up to the first interim analysis. Data can be analyzed by individual HLA types as well.

Additional feedback is expected from UK and Canadian regulators. The Company plans to provide updates regarding the resulting improved trial design, including a pathway for the Company to now pursue approval for both HLA-A*02 and non-HLA-A*02 patients using the increased statistical power of a combined analysis of the two patient groups together potentially doubling the market for GP2 by accelerating the clinical development of the non-HLA-A*02 population.

About FLAMINGO-01 Open Label Phase III Data

More than 1,300 patients have been screened with a current screen rate of approximately 800 patients per year. The 250 patient non-HLA-A*02 arm is now fully enrolled, where all patients received GLSI-100, which is 5 times more treated patients and recurrence rate data than the approximately 50 patients treated in the Phase IIb trial. The Primary Immunization Series (PIS), which includes the first 6 GLSI-100 injections over the first 6 months and is required to reach peak protection, is followed by 5 booster injections given every 6 months to prolong the immune response, thereby providing longer-term protection.

  • In the non-HLA-A*02 arm, a preliminary analysis of recurrence rates after the PIS is completed shows an approximately 70-80% reduction in recurrence rate.
  • This observation is trending similarly to the Phase IIb trial results and hazard ratio where HLA-A*02 patients were treated and where breast cancer recurrences were reduced up to 80% compared to a 20-50% reduction in recurrence rate by other approved products.
  • The immune response at baseline prior to any GLSI-100 treatment, the increasing immune response during the PIS, and the safety profile of non-HLA-A*02 patients is trending similarly to the HLA-A*02 arms of FLAMINGO-01 and to the Phase IIb study.
    • The AACR Meeting 2026 delayed-type-hypersensitivity (DTH) poster and the ASCO Meeting 2026 injection site reaction (ISR) poster can be seen and downloaded at the bottom of the Phase III clinical trial tab on the Company’s website here.
    • As shown in both posters the frequency of DTH and ISR reactions increased statistically significantly over time.
    • As reported in Table 1 of each poster, each HLA-A type exhibited more frequent immune reactivity after treatment with GLSI-100 than at baseline.
    • Baseline DTH reaction prior to any treatment suggests that GP2 may be a natural antigen and that GP2 specific T cells may exist in some patients prior to any treatment with GLSI-100. Baseline immune response to GP2 prior to any vaccination with GP2 was also observed in the Phase IIb trial and is being observed in the blinded randomized arms of FLAMINGO-01, where HLA-A*02 only patients are being vaccinated.

Analysis of the open label data from FLAMINGO-01 has been conducted in a manner that maintains the study blind. The open label recurrence rate, immune response, and safety data is based on the patients enrolled to date in FLAMINGO-01 and the data provided by the clinical sites so far, which is not completed or fully reviewed, and is thus preliminary. While comparing any preliminary FLAMINGO-01 data to the Phase IIb clinical trial data may be possible, these preliminary results are not a prediction of future results, and the results at the end of the study may differ.

About GLSI-100 Phase IIb Study

In the prospective, randomized, single-blinded, placebo-controlled, multi-center (16 sites led by MD Anderson Cancer Center) Phase IIb clinical trial of HLA-A*02 breast cancer patients, 46 HER2/neu 3+ over-expressor patients were treated with GLSI-100, and 50 placebo patients were treated with GM-CSF alone. After 5 years of follow-up, there was an 80% or greater reduction in cancer recurrences in the HER2/neu 3+ patients who were treated with GLSI-100, followed, and remained disease free over the first 6 months, which we believe is the time required to reach peak immunity and thus maximum efficacy and protection. The Phase IIb posters and results can be summarized as follows and can be seen here:

  • 80% or greater reduction in metastatic breast cancer recurrence rate over 5 years of follow-up with a peak immune response at 6 months and well-tolerated safety profile.
  • The PIS elicited a potent immune response as measured by local skin tests and immunological assays.

About FLAMINGO-01 and GLSI-100

FLAMINGO-01 (NCT05232916) is a Phase III clinical trial designed to evaluate the safety and efficacy of Fast Track designated GLSI-100 (GP2 + GM-CSF) in HER2 positive breast cancer patients who had residual disease or high-risk pathologic complete response at surgery and who have completed both neoadjuvant and postoperative adjuvant trastuzumab based treatment. The trial is led by Baylor College of Medicine and currently includes US and European clinical sites from university-based hospitals and academic and cooperative networks with plans to open up to 170-180 sites globally.

About Breast Cancer and HER2/neu Positivity

One in eight U.S. women will develop invasive breast cancer over her lifetime, with approximately 300,000 new breast cancer patients and 4 million breast cancer survivors. HER2 (human epidermal growth factor receptor 2) protein is a cell surface receptor protein that is expressed in a variety of common cancers, including in 75% of breast cancers at low (1+), intermediate (2+), and high (3+ or over-expressor) levels.

About Greenwich LifeSciences, Inc.

Greenwich LifeSciences is a clinical-stage biopharmaceutical company focused on the development of GP2, an immunotherapy to prevent breast cancer recurrences in patients who have previously undergone surgery. GP2 is a 9 amino acid transmembrane peptide of the HER2 protein, a cell surface receptor protein that is expressed in a variety of common cancers, including expression in 75% of breast cancers at low (1+), intermediate (2+), and high (3+ or over-expressor) levels. Greenwich LifeSciences has commenced a Phase III clinical trial, FLAMINGO-01. For more information on Greenwich LifeSciences, please visit the Company’s website at www.greenwichlifesciences.com and follow the Company’s Twitter at https://twitter.com/GreenwichLS.

Forward-Looking Statement Disclaimer

Statements in this press release contain “forward-looking statements” that are subject to substantial risks and uncertainties. All statements, other than statements of historical fact, contained in this press release are forward-looking statements. Forward-looking statements contained in this press release may be identified by the use of words such as “anticipate,” “believe,” “contemplate,” “could,” “estimate,” “expect,” “intend,” “seek,” “may,” “might,” “plan,” “potential,” “predict,” “project,” “target,” “aim,” “should,” “will,” “would,” or the negative of these words or other similar expressions, although not all forward-looking statements contain these words. Forward-looking statements are based on Greenwich LifeSciences Inc.’s current expectations and are subject to inherent uncertainties, risks and assumptions that are difficult to predict, including statements regarding the intended use of net proceeds from the public offering; consequently, actual results may differ materially from those expressed or implied by such forward-looking statements. Further, certain forward-looking statements are based on assumptions as to future events that may not prove to be accurate. These and other risks and uncertainties are described more fully in the section entitled “Risk Factors” in Greenwich LifeSciences’ Annual Report on the most recent Form 10-K for the year ended December 31, 2025, and other periodic reports filed with the Securities and Exchange Commission. Forward-looking statements contained in this announcement are made as of this date, and Greenwich LifeSciences, Inc. undertakes no duty to update such information except as required under applicable law.

Company Contact
Snehal Patel
Investor Relations
Office: (832) 819-3232
Email: [email protected]

Investor & Public Relations Contact for Greenwich LifeSciences
Dave Gentry
RedChip Companies Inc.
Office: 1-800-RED CHIP (733 2447)
Email: [email protected]

Primary Logo

Source: Greenwich LifeSciences, Inc.

Released July 16, 2026

Release – Greenwich LifeSciences Announces European Approval for Use of Commercially Manufactured GP2 in FLAMINGO-01

Posted on by [email protected]
Greenwich LifeSciences

Research News and Market Data on GLSI

 Download as PDF July 09, 2026 6:00am EDT

STAFFORD, Texas, July 09, 2026 (GLOBE NEWSWIRE) — Greenwich LifeSciences, Inc. (Nasdaq: GLSI) (the “Company”), a clinical-stage biopharmaceutical company focused on its Phase III clinical trial, FLAMINGO-01, which is evaluating GLSI-100, an immunotherapy to prevent breast cancer recurrences, today provided the following update on the use of commercially manufactured GP2 in FLAMINGO-01 in Europe.

All European and US Sites to Treat Patients with Commercially Manufactured GP2

The Company previously announced that the first three commercial lots of GP2 active ingredient were manufactured in 2023 in an approved commercial facility, which could be used to prepare approximately 200,000 doses of GP2. In 2024, the first commercial lot filling GP2 into vials for commercial sale or for clinical use was manufactured in a commercial facility. In addition, drug stability programs were initiated for all four lots. Data on these commercial lots was submitted to the FDA, and after review, the first commercial lot of GP2 vials was approved for use in FLAMINGO-01 in the US in early 2026. All approximately 40-50 US sites have been supplied with commercially manufactured GP2 vials and have begun treating patients with these vials. We were able to efficiently distribute the GP2 vials and communicate with the US pharmacists working with our warehouse partners and through our clinical team, which we internalized in Q4 2025.

The European Medicines Agency (EMA) has completed their review and will also allow use of the same commercially manufactured GP2 lot in FLAMINGO-01 in Europe. Thus, all clinical sites in the US and Europe, which have increased from 160 sites to approximately 170-180 sites, are expected to be using the same lot with shipments to European pharmacies already under way. We are now seeking approval to use this lot in the UK and Canada in separate and independent regulatory processes.

About FLAMINGO-01 Open Label Phase III Data

More than 1,300 patients have been screened with a current screen rate of approximately 800 patients per year. The 250 patient non-HLA-A*02 arm is now fully enrolled, where all patients received GLSI-100, which is 5 times more treated patients and recurrence rate data than the approximately 50 patients treated in the Phase IIb trial. The Primary Immunization Series (PIS), which includes the first 6 GLSI-100 injections over the first 6 months and is required to reach peak protection, is followed by 5 booster injections given every 6 months to prolong the immune response, thereby providing longer-term protection.

  • In the non-HLA-A*02 arm, a preliminary analysis of recurrence rates after the PIS is completed shows an approximately 70-80% reduction in recurrence rate.
  • This observation is trending similarly to the Phase IIb trial results and hazard ratio where HLA-A*02 patients were treated and where breast cancer recurrences were reduced up to 80% compared to a 20-50% reduction in recurrence rate by other approved products.
  • The immune response at baseline prior to any GLSI-100 treatment, the increasing immune response during the PIS, and the safety profile of non-HLA-A*02 patients is trending similarly to the HLA-A*02 arms of FLAMINGO-01 and to the Phase IIb study.
    • The AACR Meeting 2026 delayed-type-hypersensitivity (DTH) poster and the ASCO Meeting 2026 injection site reaction (ISR) poster can be seen and downloaded at the bottom of the Phase III clinical trial tab on the Company’s website here.
    • As shown in both posters the frequency of DTH and ISR reactions increased statistically significantly over time.
    • As reported in Table 1 of each poster, each HLA-A type exhibited more frequent immune reactivity after treatment with GLSI-100 than at baseline.
    • Baseline DTH reaction prior to any treatment suggests that GP2 may be a natural antigen and that GP2 specific T cells may exist in some patients prior to any treatment with GLSI-100. Baseline immune response to GP2 prior to any vaccination with GP2 was also observed in the Phase IIb trial and is being observed in the blinded randomized arms of FLAMINGO-01, where HLA-A*02 only patients are being vaccinated.

Analysis of the open label data from FLAMINGO-01 has been conducted in a manner that maintains the study blind. The open label recurrence rate, immune response, and safety data is based on the patients enrolled to date in FLAMINGO-01 and the data provided by the clinical sites so far, which is not completed or fully reviewed, and is thus preliminary. While comparing any preliminary FLAMINGO-01 data to the Phase IIb clinical trial data may be possible, these preliminary results are not a prediction of future results, and the results at the end of the study may differ.

About GLSI-100 Phase IIb Study

In the prospective, randomized, single-blinded, placebo-controlled, multi-center (16 sites led by MD Anderson Cancer Center) Phase IIb clinical trial of HLA-A*02 breast cancer patients, 46 HER2/neu 3+ over-expressor patients were treated with GLSI-100, and 50 placebo patients were treated with GM-CSF alone. After 5 years of follow-up, there was an 80% or greater reduction in cancer recurrences in the HER2/neu 3+ patients who were treated with GLSI-100, followed, and remained disease free over the first 6 months, which we believe is the time required to reach peak immunity and thus maximum efficacy and protection. The Phase IIb posters and results can be summarized as follows and can be seen here:

  • 80% or greater reduction in metastatic breast cancer recurrence rate over 5 years of follow-up with a peak immune response at 6 months and well-tolerated safety profile.
  • The PIS elicited a potent immune response as measured by local skin tests and immunological assays.

About FLAMINGO-01 and GLSI-100

FLAMINGO-01 (NCT05232916) is a Phase III clinical trial designed to evaluate the safety and efficacy of Fast Track designated GLSI-100 (GP2 + GM-CSF) in HER2 positive breast cancer patients who had residual disease or high-risk pathologic complete response at surgery and who have completed both neoadjuvant and postoperative adjuvant trastuzumab based treatment. The trial is led by Baylor College of Medicine and currently includes US and European clinical sites from university-based hospitals and academic and cooperative networks with plans to open up to 170-180 sites globally.

For more information on FLAMINGO-01, please visit the Company’s website here and clinicaltrials.gov here. Contact information and an interactive map of the majority of participating clinical sites can be viewed under the “Contacts and Locations” section. Please note that the interactive map is not viewable on mobile screens. Related questions and participation interest can be emailed to: [email protected]

About Breast Cancer and HER2/neu Positivity

One in eight U.S. women will develop invasive breast cancer over her lifetime, with approximately 300,000 new breast cancer patients and 4 million breast cancer survivors. HER2 (human epidermal growth factor receptor 2) protein is a cell surface receptor protein that is expressed in a variety of common cancers, including in 75% of breast cancers at low (1+), intermediate (2+), and high (3+ or over-expressor) levels.

About Greenwich LifeSciences, Inc.

Greenwich LifeSciences is a clinical-stage biopharmaceutical company focused on the development of GP2, an immunotherapy to prevent breast cancer recurrences in patients who have previously undergone surgery. GP2 is a 9 amino acid transmembrane peptide of the HER2 protein, a cell surface receptor protein that is expressed in a variety of common cancers, including expression in 75% of breast cancers at low (1+), intermediate (2+), and high (3+ or over-expressor) levels. Greenwich LifeSciences has commenced a Phase III clinical trial, FLAMINGO-01. For more information on Greenwich LifeSciences, please visit the Company’s website at www.greenwichlifesciences.com and follow the Company’s Twitter at https://twitter.com/GreenwichLS.

Forward-Looking Statement Disclaimer

Statements in this press release contain “forward-looking statements” that are subject to substantial risks and uncertainties. All statements, other than statements of historical fact, contained in this press release are forward-looking statements. Forward-looking statements contained in this press release may be identified by the use of words such as “anticipate,” “believe,” “contemplate,” “could,” “estimate,” “expect,” “intend,” “seek,” “may,” “might,” “plan,” “potential,” “predict,” “project,” “target,” “aim,” “should,” “will,” “would,” or the negative of these words or other similar expressions, although not all forward-looking statements contain these words. Forward-looking statements are based on Greenwich LifeSciences Inc.’s current expectations and are subject to inherent uncertainties, risks and assumptions that are difficult to predict, including statements regarding the intended use of net proceeds from the public offering; consequently, actual results may differ materially from those expressed or implied by such forward-looking statements. Further, certain forward-looking statements are based on assumptions as to future events that may not prove to be accurate. These and other risks and uncertainties are described more fully in the section entitled “Risk Factors” in Greenwich LifeSciences’ Annual Report on the most recent Form 10-K for the year ended December 31, 2025, and other periodic reports filed with the Securities and Exchange Commission. Forward-looking statements contained in this announcement are made as of this date, and Greenwich LifeSciences, Inc. undertakes no duty to update such information except as required under applicable law.

Company Contact
Snehal Patel
Investor Relations
Office: (832) 819-3232
Email: [email protected]

Investor & Public Relations Contact for Greenwich LifeSciences
Dave Gentry
RedChip Companies Inc.
Office: 1-800-RED CHIP (733 2447)
Email: [email protected]

Primary Logo

Source: Greenwich LifeSciences, Inc.

Released July 9, 2026

Greenwich LifeSciences, Inc. (GLSI) – Additional Phase 3 FLAMINGO-01 Data Presented At ASCO Meeting

Posted on by [email protected]


Tuesday, June 02, 2026

Robert LeBoyer, Senior Vice President, Equity Research Analyst, Biotechnology, Noble Capital Markets, Inc.

Refer to the full report for the price target, fundamental analysis, and rating.

Additional Data Presented At ASCO. Greenwich LifeSciences presented an abstract and poster at the ASCO Annual Meeting.  The data assessed non-HLA-A*02 patients in the open-label arm after six monthly doses of GLA-100. The data show statistically significant injection site reaction (ISR) and immune response at baseline, with increases over time.

Patients Were Evaluated After Initial Immune Stimulation. Patients received the Primary Immunization Series (PIS), consisting of six vaccinations over the first six months of the trial. The fourth, fifth, and sixth vaccinations showed a significant increase in the percentage of patients showing an ISR compared to baseline. Of the 247 patients enrolled, 208 had both baseline vaccination and assessments at 4, 5, or 6 months.


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Release – Greenwich LifeSciences Provides Update Regarding Form 10-K Filing

Posted on by [email protected]

Research News and Market Data on GLSI

 Download as PDFJune 01, 2026 6:00am EDT

STAFFORD, Texas, June 01, 2026 (GLOBE NEWSWIRE) — Greenwich LifeSciences, Inc. (Nasdaq: GLSI) (the “Company”), a clinical-stage biopharmaceutical company focused on its Phase III clinical trial, FLAMINGO-01, which is evaluating Fast Track designated GLSI-100, an immunotherapy to prevent breast cancer recurrences, today provided an update on its Form 10-K filing for the fiscal year ending December 31, 2025.

The Form 10-K for the fiscal year ending December 31, 2025, continues to be audited by our new auditor and we believe it is in the final approval steps. The Form 10-K also includes the 2024 audit that was previously audited by the prior auditor. As previously indicated, the accounts payable adjustments are related to the large global Phase III clinical trial underway and the unexpectedly large increase in screening and patient enrollment in Europe in 2024 and 2025. Both auditors in a dual auditor filing must agree in order to make timely filings, which did not occur in March or April, and such coordination is still required as part of the final approval steps.

The Company believes that it did not contribute to the delays in filing and instead did everything possible to file on time. The Company provided the 10K filing information with large increases to accounts payable to the auditors for review in early February 2026 and requested and anticipated an early filing. The Company has further improved its accounts payable estimations using current clinical trial data in its financials for Form 10-Q for the period ending March 31, 2026.

The Company believes that the accounts payable adjustments are not material to the Company or its investors and does not change the fundamentals of the Company. The shift in expenses does not change the cash balance or the net cash used in operating activities of the Company. As previously announced, the Company’s ending cash balance as of March 31, 2026 is approximately $10.5 million, which the Company believes is an improvement over 2025 ending cash balances, and includes the retirement of over 75% of accounts payable for the fiscal year ending December 31, 2025. This $10.5 million cash balance is more than the 2025 net cash used in operating activities which is approximately $9.9 million. The above figures are unaudited and are subject to change following the completion of the Company’s financial audit for the year ending December 31, 2025 and the review for the period ending March 31, 2026.

About FLAMINGO-01 Open Label Phase III Data

More than 1,300 patients have been screened with a current screen rate of approximately 800 patients per year. The 250 patient non-HLA-A*02 arm is now fully enrolled, where all patients received GLSI-100, which is 5 times more treated patients and recurrence rate data than the approximately 50 patients treated in the Phase IIb trial. The Primary Immunization Series (PIS), which includes the first 6 GLSI-100 injections over the first 6 months and is required to reach peak protection, is followed by 5 booster injections given every 6 months to prolong the immune response, thereby providing longer-term protection.

  • In the non-HLA-A*02 arm, a preliminary analysis of recurrence rates after the PIS is completed shows an approximately 70-80% reduction in recurrence rate.
  • This observation is trending similarly to the Phase IIb trial results and hazard ratio where HLA-A*02 patients were treated and where breast cancer recurrences were reduced up to 80% compared to a 20-50% reduction in recurrence rate by other approved products.
  • The immune response at baseline prior to any GLSI-100 treatment, the increasing immune response during the PIS, and the safety profile of non-HLA-A*02 patients is trending similarly to the HLA-A*02 arms of FLAMINGO-01 and to the Phase IIb study.
    • The AACR Meeting 2026 delayed-type-hypersensitivity (DTH) poster can be downloaded here.
    • The frequency of DTH reactions increased by approximately 4x (290%) in the total open-label non-HLA-A*02 population, increasing from 5.2% of the patients experiencing a DTH reaction at baseline, prior to any GLSI-100 administration, to 20.4% of the patients experiencing a DTH reaction in month 4 or month 6 (McNemar, p < 0.001).
    • As reported in Table 1 of the poster, each HLA-A type exhibited more frequent immune reactivity after treatment with GLSI-100 than at baseline with frequency increasing from 100% to 700%.
    • Baseline DTH reaction prior to any treatment suggests that GP2 may be a natural antigen and that GP2 specific T cells may exist in some patients prior to any treatment with GLSI-100. Baseline immune response to GP2 prior to any vaccination with GP2 was also observed in the Phase IIb trial and is being observed in the blinded randomized arms of FLAMINGO-01, where HLA-A*02 only patients are being vaccinated.

Analysis of the open label data from FLAMINGO-01 has been conducted in a manner that maintains the study blind. The open label recurrence rate, immune response, and safety data is based on the patients enrolled to date in FLAMINGO-01 and the data provided by the clinical sites so far, which is not completed or fully reviewed, and is thus preliminary. While comparing any preliminary FLAMINGO-01 data to the Phase IIb clinical trial data may be possible, these preliminary results are not a prediction of future results, and the results at the end of the study may differ.

About GLSI-100 Phase IIb Study

In the prospective, randomized, single-blinded, placebo-controlled, multi-center (16 sites led by MD Anderson Cancer Center) Phase IIb clinical trial of HLA-A*02 breast cancer patients, 46 HER2/neu 3+ over-expressor patients were treated with GLSI-100, and 50 placebo patients were treated with GM-CSF alone. After 5 years of follow-up, there was an 80% or greater reduction in cancer recurrences in the HER2/neu 3+ patients who were treated with GLSI-100, followed, and remained disease free over the first 6 months, which we believe is the time required to reach peak immunity and thus maximum efficacy and protection. The Phase IIb results can be summarized as follows:

  • 80% or greater reduction in metastatic breast cancer recurrence rate over 5 years of follow-up with a peak immune response at 6 months and well-tolerated safety profile.
  • The PIS elicited a potent immune response as measured by local skin tests and immunological assays.

About FLAMINGO-01 and GLSI-100

FLAMINGO-01 (NCT05232916) is a Phase III clinical trial designed to evaluate the safety and efficacy of Fast Track designated GLSI-100 (GP2 + GM-CSF) in HER2 positive breast cancer patients who had residual disease or high-risk pathologic complete response at surgery and who have completed both neoadjuvant and postoperative adjuvant trastuzumab based treatment. The trial is led by Baylor College of Medicine and currently includes US and European clinical sites from university-based hospitals and academic and cooperative networks with plans to open up to 150 sites globally. In the double-blinded arms of the Phase III trial, approximately 500 HLA-A*02 patients are planned to be randomized to GLSI-100 or placebo, and up to 250 patients of other HLA types are planned to be treated with GLSI-100 in a third arm. The trial has been designed to detect a hazard ratio of 0.3 in invasive breast cancer-free survival, where 28 events will be required. An interim analysis for superiority and futility will be conducted when at least half of those events, 14, have occurred. This sample size provides 80% power if the annual rate of events in placebo-treated subjects is 2.4% or greater.

For more information on FLAMINGO-01, please visit the Company’s website here and clinicaltrials.gov here. Contact information and an interactive map of the majority of participating clinical sites can be viewed under the “Contacts and Locations” section. Please note that the interactive map is not viewable on mobile screens. Related questions and participation interest can be emailed to: [email protected]

About Breast Cancer and HER2/neu Positivity

One in eight U.S. women will develop invasive breast cancer over her lifetime, with approximately 300,000 new breast cancer patients and 4 million breast cancer survivors. HER2 (human epidermal growth factor receptor 2) protein is a cell surface receptor protein that is expressed in a variety of common cancers, including in 75% of breast cancers at low (1+), intermediate (2+), and high (3+ or over-expressor) levels.

About Greenwich LifeSciences, Inc.

Greenwich LifeSciences is a clinical-stage biopharmaceutical company focused on the development of GP2, an immunotherapy to prevent breast cancer recurrences in patients who have previously undergone surgery. GP2 is a 9 amino acid transmembrane peptide of the HER2 protein, a cell surface receptor protein that is expressed in a variety of common cancers, including expression in 75% of breast cancers at low (1+), intermediate (2+), and high (3+ or over-expressor) levels. Greenwich LifeSciences has commenced a Phase III clinical trial, FLAMINGO-01. For more information on Greenwich LifeSciences, please visit the Company’s website at www.greenwichlifesciences.com and follow the Company’s Twitter at https://twitter.com/GreenwichLS.

Forward-Looking Statement Disclaimer

Statements in this press release contain “forward-looking statements” that are subject to substantial risks and uncertainties. All statements, other than statements of historical fact, contained in this press release are forward-looking statements. Forward-looking statements contained in this press release may be identified by the use of words such as “anticipate,” “believe,” “contemplate,” “could,” “estimate,” “expect,” “intend,” “seek,” “may,” “might,” “plan,” “potential,” “predict,” “project,” “target,” “aim,” “should,” “will,” “would,” or the negative of these words or other similar expressions, although not all forward-looking statements contain these words. Forward-looking statements are based on Greenwich LifeSciences Inc.’s current expectations and are subject to inherent uncertainties, risks and assumptions that are difficult to predict, including statements regarding the intended use of net proceeds from the public offering; consequently, actual results may differ materially from those expressed or implied by such forward-looking statements. Further, certain forward-looking statements are based on assumptions as to future events that may not prove to be accurate. These and other risks and uncertainties are described more fully in the section entitled “Risk Factors” in Greenwich LifeSciences’ Annual Report on the most recent Form 10-K for the year ended December 31, 2024, and other periodic reports filed with the Securities and Exchange Commission. Forward-looking statements contained in this announcement are made as of this date, and Greenwich LifeSciences, Inc. undertakes no duty to update such information except as required under applicable law.

Company Contact
Snehal Patel
Investor Relations
Office: (832) 819-3232
Email: [email protected]

Investor & Public Relations Contact for Greenwich LifeSciences
Dave Gentry
RedChip Companies Inc.
Office: 1-800-RED CHIP (733 2447)
Email: [email protected]

Primary Logo

Source: Greenwich LifeSciences, Inc.

Released June 1, 2026

Release – Greenwich LifeSciences Presents FLAMINGO-01 Phase III Trial Open Label Data Published at ASCO Meeting 2026

Posted on by [email protected]
Greenwich LifeSciences

Research News and Market Data on GLSI

 Download as PDFJune 01, 2026 8:15am EDT

STAFFORD, Texas, June 01, 2026 (GLOBE NEWSWIRE) — Greenwich LifeSciences, Inc. (Nasdaq: GLSI) (the “Company”), a clinical-stage biopharmaceutical company focused on its Phase III clinical trial, FLAMINGO-01, which is evaluating Fast Track designated GLSI-100, an immunotherapy to prevent breast cancer recurrences, today presents the published abstract and poster from the ASCO Annual Meeting 2026.

The abstract is shown below and the poster being presented today can be seen and downloaded at the bottom of the Phase III clinical trial tab on the Company’s website here.

  • This is the second abstract and poster presented jointly with the Steering Committee of FLAMINGO-01 with statistically significant injection site reaction (ISR) immune response data, with subgroup analysis by the most prevalent HLA types.
  • In the non-HLA-A*02 open label arm where all patients (n=247) were treated with GLSI-100, immune responses to GP2 were measured at baseline and over time using skin tests (DTH) and ISRs.
  • An ISR reaction, erythema (redness) or induration (white hard bump), was used to assess in vivo immune responses in patients. The diameter of the reaction was assessed 48-72 hours after injection but is not reported here.
  • In this preliminary data analysis, there was a significant increase in percentage of patients experiencing an ISR reaction (for both erythema and induration) in vaccination 4, vaccination 5 or vaccination 6 compared to the baseline vaccination. There were 208 patients with both baseline vaccination and vaccination 4, 5 or 6 assessments.
  • Erythema: There was a significant increase in the percentage of patients experiencing erythema ISRs after the 4th, 5th or 6th vaccination compared to the ISRs from the 1st vaccination. In this preliminary analysis, the frequency of ISRs increased significantly from 20.2% of the patients experiencing an ISR after the first vaccination to 55.3% of the patients experiencing an ISR after the 4th, 5th or 6th vaccination (McNemar p < 0.001), representing an increase of 2.7x or 174%.
  • Induration: There was a significant increase in the percentage of patients experiencing induration ISRs after the 4th, 5th or 6th vaccination compared to the ISRs from the 1st vaccination. In this preliminary analysis, the frequency of ISRs increased significantly from 14.9% of the patients experiencing an ISR after the first vaccination to 34.6% of the patients experiencing an ISR after the 4th, 5th or 6th vaccination (McNemar p < 0.001), representing an increase of 2.3x or 132%.
  • As reported in Table 1, each HLA-A type exhibited more frequent immune reactivity with increased GLSI-100 vaccinations with frequency increasing by 60% to 280% over the frequency after the first vaccination. These results are consistent with the GP2 DTH results presented at AACR.
  • Mechanism of Action: A positive immune response is an indicator that the immune system has been activated against recurring cancer cells, potentially leading to the prevention of metastatic breast cancer. The Company previously announced that in the non-HLA-A*02 arm, a preliminary analysis of recurrence rates after the Primary Immunization Series (PIS) is completed shows an approximately 70-80% reduction in recurrence rate. Thus, the immune response data is supporting the mechanism of action that reduces recurrences and prevents metastatic breast cancer.
  • This statistically significant non-HLA-A*02 open label arm immune response data for both DTH and ISRs is trending similarly to the immune response data in the HLA-A*02 patients in the Phase IIb study and the HLA-A*02 arms of FLAMINGO-01. The study is ongoing and data collection and cleaning continue, while some patients may still be in their PIS vaccination phase, so final results may vary.

The immune response abstract and poster conclusion: The statistically significant increase in the incidence of ISR reactions over time found in this preliminary analysis of GLSI-100 treated non-HLA-A*02 patients shows that GLSI-100 treatment should not be limited to HLA-A*02 patients. Patients treated with GLSI-100 were increasingly able to mount an immune response to GP2 as evidenced in this preliminary data. Future investigations may explore the use of immune responses to assess correlation of DTH to ISRs, immunogenicity of GLSI-100 by specific HLA type, timing of boosters to sustain immunity, clinical site performance, and the discontinuation of treatment for non-responders.

CEO Snehal Patel commented, “The DTH immune response data presented at AACR and the ISR immune response data presented today together further support the mechanism of action and the combination of HLA-A*02 and non-HLA-A*02 patients in the same randomized arms, potentially improving the chances of success at the interim analysis and more than doubling the market potential for GLSI-100. This combination of patients, independent of HLA type, has already started in the US and may soon start in Europe. In addition to ASCO, the Company previously attended AACR and ESMO Breast and plans to attend BIO partnering and investor conferences in the coming months, while presenting additional FLAMINGO-01 data at any time.”

The abstract from today’s immune response data and the members of the Steering Committee follow:

Abstract Number: LBA538 – Poster Section 23 on June 1, 2026, 1:30 – 4:30pm CT

Abstract Title: Preliminary injection site reaction immune response results from open-label arm of on-going Phase III study to evaluate the efficacy and safety of GLSI-100 (GP2 + GM-CSF) in breast cancer patients with residual disease or high-risk PCR after both neo-adjuvant and postoperative adjuvant anti-HER2 therapy, Flamingo-01

Snehal S. Patel1, Jaye Thompson1, F. Joseph Daugherty1, Francois-Clement Bidard2, William J. Gradishar3, Miguel Martin4, Joyce A. O’Shaughnessy5, Hope S. Rugo6, Cesar A. Santa-Maria7, Marcus Schmidt8, Laura M. Spring9, and Mothaffar F. Rimawi10

1Greenwich LifeSciences, Stafford, TX,2Institut Curie, Paris, France,3Northwestern University, Chicago, IL, 4GEICAM, Madrid, Spain,5Sarah Cannon Research Institute, Dallas, TX,6City of Hope Comprehensive Cancer Center, Duarte, CA,7Johns Hopkins University, Baltimore, MD,8University Medical Center Mainz, Mainz, Germany,9Massachusetts General Hospital, Boston, MA,10Lester and Sue Smith Breast Center, Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX

Background: This Phase III trial is a prospective, randomized, double-blinded, multi-center study (NCT05232916) in HLA-A*02 patients at approximately 140 sites in the US and Europe. A third non-randomized arm of approximately 250 non-HLA-A*02 patients is now fully enrolled and preliminary immune response data is presented below. GP2 is a biologic nine amino acid peptide of the HER2/neu protein delivered in combination with Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) that stimulates an immune response targeting HER2/neu expressing cancers, the combination known as GLSI-100.

Methods: After standard of care neoadjuvant and adjuvant therapy, 6 intradermal injections of GLSI-100 will be administered over the first 6 months and 5 subsequent boosters will be administered over the next 2.5 years. The participant duration of the trial will be 3 years treatment plus 1 additional year follow-up. Immune responses to GP2 were measured over time using delayed-type-hypersensitivity (DTH) skin tests and injection site reactions (ISRs). The patient population is defined by these key eligibility criteria: 1) HER2/neu positive and HLA, 2) Residual disease or High risk pCR (Stage III at presentation) post neo-adjuvant therapy, 3) Exclude Stage IV, and 4) Completed at least 90% of planned adjuvant trastuzumab-based therapy.

Results: All patients (n=247) were vaccinated with GLSI-100. Injection site reactions, erythema (redness) was assessed at various time points and represent an in vivo immune response in patients. The ISR orthogonal mean was measured 48-72 hours following vaccination with GLSI-100. For GP2 treated patients, there was a significant increase in the percentage of patients experiencing ISRs in the 4th, 5th or 6th vaccination compared to the ISRs from the 1st vaccination. In this preliminary analysis, the frequency of ISRs increased significantly from 20.2% of the patients experiencing an ISR after the first vaccination to 55.3% of the patients experiencing an ISR after the 4th, 5th or 6th vaccination (McNemar p < 0.001). The study is ongoing and data collection and cleaning continue so final results may vary.

Conclusions: Preliminary injection site reaction data comparing vaccination over time in GLSI-100 treated non-HLA-A*02 patients showed a significant increase in immune response. Future studies may explore the use of immune responses to assess: correlation of DTH to ISRs, immunogenicity of GLSI-100 by specific HLA type, timing of boosters to sustain immunity, clinical site performance, and the discontinuation of treatment for non-responders.

The Steering Committee authoring abstract LBA538 is comprised of the following experts in the field of breast cancer oncology representing prominent teaching hospitals in the US and 4 of the largest breast oncology networks in the US, Germany, France, and Spain:

  • Dr. Mothaffar F. Rimawi – Professor of Medicine at the Baylor College of Medicine and Executive Medical Director and Co-Leader, Breast Cancer Program of the Dan L Duncan Comprehensive Cancer Center
  • Dr. Francois-Clement Bidard – Professor of Medical Oncology, UVSQ/Paris Saclay University, Head of Breast Cancer Group, Institut Curie, Vice-Chair of the French Breast Cancer research group UCBG (Unicancer)
  • Dr. William J. Gradishar – Professor of Medicine at the Feinberg School of Medicine at Northwestern University, Chief of Hematology and Oncology in the Department of Medicine, and Betsy Bramsen Professor of Breast Oncology
  • Dr. Sibylle Loibl – Professor (apl) Goethe University Frankfurt/M, Clinical Consultant Centre for Haematology and Oncology/Bethanien Frankfurt/M, CEO of GBG Forschungs GmbH & Chair of the German Breast Group (GBG)
  • Dr. Miguel Martin – Professor of Medicine, Head, Medical Oncology Service, Gregorio Marañón General University Hospital, Complutense University, Madrid, CEO of GEICAM
  • Dr. Joyce A. O’Shaughnessy – Celebrating Women Chair in Breast Cancer, Baylor University Medical Center and Chair, Breast Cancer Program, Texas Oncology, US Oncology, Dallas, Texas
  • Dr. Hope S. Rugo – Director, Women’s Cancers Program, Division Chief, Breast Medical Oncology, Professor, Department of Medical Oncology & Therapeutics Research, City of Hope Comprehensive Cancer Center, Professor Emeritus, University of California, San Francisco
  • Dr. Cesar A. Santa-Maria – Associate Professor of Oncology, Breast and Gynecological Malignancies Group, Director of Breast Cancer Trials, Johns Hopkins Sidney Kimmel Comprehensive Cancer Center
  • Dr. Laura M. Spring – Assistant Professor, Medicine, Harvard Medical School, Attending Physician, Medical Oncology, Massachusetts General Hospital

About the 2026 ASCO Annual Meeting

ASCO is the world’s leading professional organization for physicians and oncology professionals caring for people with cancer. ASCO offers premier scientific events for oncology professionals, patient advocates, industry representatives, and major media outlets worldwide. The ASCO Annual Meeting program features poster presentations, poster discussion sessions, clinical science symposia, and dynamic education sessions about recent advancements in cancer research, treatment, and patient care. For more information, please visit the conference website at: https://conferences.asco.org/am/attend.

About FLAMINGO-01 Open Label Phase III Data

More than 1,300 patients have been screened with a current screen rate of approximately 800 patients per year. The 250 patient non-HLA-A*02 arm is now fully enrolled, where all patients received GLSI-100, which is 5 times more treated patients and recurrence rate data than the approximately 50 patients treated in the Phase IIb trial. The Primary Immunization Series (PIS), which includes the first 6 GLSI-100 injections over the first 6 months and is required to reach peak protection, is followed by 5 booster injections given every 6 months to prolong the immune response, thereby providing longer-term protection.

  • In the non-HLA-A*02 arm, a preliminary analysis of recurrence rates after the PIS is completed shows an approximately 70-80% reduction in recurrence rate.
  • This observation is trending similarly to the Phase IIb trial results and hazard ratio where HLA-A*02 patients were treated and where breast cancer recurrences were reduced up to 80% compared to a 20-50% reduction in recurrence rate by other approved products.
  • The immune response at baseline prior to any GLSI-100 treatment, the increasing immune response during the PIS, and the safety profile of non-HLA-A*02 patients is trending similarly to the HLA-A*02 arms of FLAMINGO-01 and to the Phase IIb study.
    • The AACR Meeting 2026 delayed-type-hypersensitivity (DTH) poster and the ASCO Meeting 2026 injection site reaction (ISR) posters can be seen and downloaded at the bottom of the Phase III clinical trial tab on the Company’s website here.
    • As shown in both posters the frequency of DTH and ISR reactions increased statistically significantly over time.
    • As reported in Table 1 of each poster, each HLA-A type exhibited more frequent immune reactivity after treatment with GLSI-100 than at baseline.
    • Baseline DTH reaction prior to any treatment suggests that GP2 may be a natural antigen and that GP2 specific T cells may exist in some patients prior to any treatment with GLSI-100. Baseline immune response to GP2 prior to any vaccination with GP2 was also observed in the Phase IIb trial and is being observed in the blinded randomized arms of FLAMINGO-01, where HLA-A*02 only patients are being vaccinated.

Analysis of the open label data from FLAMINGO-01 has been conducted in a manner that maintains the study blind. The open label recurrence rate, immune response, and safety data is based on the patients enrolled to date in FLAMINGO-01 and the data provided by the clinical sites so far, which is not completed or fully reviewed, and is thus preliminary. While comparing any preliminary FLAMINGO-01 data to the Phase IIb clinical trial data may be possible, these preliminary results are not a prediction of future results, and the results at the end of the study may differ.

About GLSI-100 Phase IIb Study

In the prospective, randomized, single-blinded, placebo-controlled, multi-center (16 sites led by MD Anderson Cancer Center) Phase IIb clinical trial of HLA-A*02 breast cancer patients, 46 HER2/neu 3+ over-expressor patients were treated with GLSI-100, and 50 placebo patients were treated with GM-CSF alone. After 5 years of follow-up, there was an 80% or greater reduction in cancer recurrences in the HER2/neu 3+ patients who were treated with GLSI-100, followed, and remained disease free over the first 6 months, which we believe is the time required to reach peak immunity and thus maximum efficacy and protection. The Phase IIb posters and results can be summarized as follows and can be seen here:

  • 80% or greater reduction in metastatic breast cancer recurrence rate over 5 years of follow-up with a peak immune response at 6 months and well-tolerated safety profile.
  • The PIS elicited a potent immune response as measured by local skin tests and immunological assays.

About FLAMINGO-01 and GLSI-100

FLAMINGO-01 (NCT05232916) is a Phase III clinical trial designed to evaluate the safety and efficacy of Fast Track designated GLSI-100 (GP2 + GM-CSF) in HER2 positive breast cancer patients who had residual disease or high-risk pathologic complete response at surgery and who have completed both neoadjuvant and postoperative adjuvant trastuzumab based treatment. The trial is led by Baylor College of Medicine and currently includes US and European clinical sites from university-based hospitals and academic and cooperative networks with plans to open up to 150 sites globally. In the double-blinded arms of the Phase III trial, approximately 500 HLA-A*02 patients are planned to be randomized to GLSI-100 or placebo, and up to 250 patients of other HLA types are planned to be treated with GLSI-100 in a third arm. The trial has been designed to detect a hazard ratio of 0.3 in invasive breast cancer-free survival, where 28 events will be required. An interim analysis for superiority and futility will be conducted when at least half of those events, 14, have occurred. This sample size provides 80% power if the annual rate of events in placebo-treated subjects is 2.4% or greater.

For more information on FLAMINGO-01, please visit the Company’s website here and clinicaltrials.gov here. Contact information and an interactive map of the majority of participating clinical sites can be viewed under the “Contacts and Locations” section. Please note that the interactive map is not viewable on mobile screens. Related questions and participation interest can be emailed to: [email protected]

About Breast Cancer and HER2/neu Positivity

One in eight U.S. women will develop invasive breast cancer over her lifetime, with approximately 300,000 new breast cancer patients and 4 million breast cancer survivors. HER2 (human epidermal growth factor receptor 2) protein is a cell surface receptor protein that is expressed in a variety of common cancers, including in 75% of breast cancers at low (1+), intermediate (2+), and high (3+ or over-expressor) levels.

About Greenwich LifeSciences, Inc.

Greenwich LifeSciences is a clinical-stage biopharmaceutical company focused on the development of GP2, an immunotherapy to prevent breast cancer recurrences in patients who have previously undergone surgery. GP2 is a 9 amino acid transmembrane peptide of the HER2 protein, a cell surface receptor protein that is expressed in a variety of common cancers, including expression in 75% of breast cancers at low (1+), intermediate (2+), and high (3+ or over-expressor) levels. Greenwich LifeSciences has commenced a Phase III clinical trial, FLAMINGO-01. For more information on Greenwich LifeSciences, please visit the Company’s website at www.greenwichlifesciences.com and follow the Company’s Twitter at https://twitter.com/GreenwichLS.

Forward-Looking Statement Disclaimer

Statements in this press release contain “forward-looking statements” that are subject to substantial risks and uncertainties. All statements, other than statements of historical fact, contained in this press release are forward-looking statements. Forward-looking statements contained in this press release may be identified by the use of words such as “anticipate,” “believe,” “contemplate,” “could,” “estimate,” “expect,” “intend,” “seek,” “may,” “might,” “plan,” “potential,” “predict,” “project,” “target,” “aim,” “should,” “will,” “would,” or the negative of these words or other similar expressions, although not all forward-looking statements contain these words. Forward-looking statements are based on Greenwich LifeSciences Inc.’s current expectations and are subject to inherent uncertainties, risks and assumptions that are difficult to predict, including statements regarding the intended use of net proceeds from the public offering; consequently, actual results may differ materially from those expressed or implied by such forward-looking statements. Further, certain forward-looking statements are based on assumptions as to future events that may not prove to be accurate. These and other risks and uncertainties are described more fully in the section entitled “Risk Factors” in Greenwich LifeSciences’ Annual Report on the most recent Form 10-K for the year ended December 31, 2024, and other periodic reports filed with the Securities and Exchange Commission. Forward-looking statements contained in this announcement are made as of this date, and Greenwich LifeSciences, Inc. undertakes no duty to update such information except as required under applicable law.

Company Contact
Snehal Patel
Investor Relations
Office: (832) 819-3232
Email: [email protected]

Investor & Public Relations Contact for Greenwich LifeSciences
Dave Gentry
RedChip Companies Inc.
Office: 1-800-RED CHIP (733 2447)
Email: [email protected]

Primary Logo

Source: Greenwich LifeSciences, Inc.

Released June 1, 2026

Release – Greenwich LifeSciences Provides Update Regarding Form 10-K Filing

Posted on by [email protected]
Greenwich LifeSciences

Research News and Market Data on GLSI

 Download as PDF April 30, 2026 6:00am EDT

STAFFORD, Texas, April 30, 2026 (GLOBE NEWSWIRE) — Greenwich LifeSciences, Inc. (Nasdaq: GLSI) (the “Company”), a clinical-stage biopharmaceutical company focused on its Phase III clinical trial, FLAMINGO-01, which is evaluating Fast Track designated GLSI-100, an immunotherapy to prevent breast cancer recurrences, today provided an update on its Form 10-K filing for the fiscal year ending December 31, 2025.

The Form 10-K for the fiscal year ending December 31, 2025 is still being audited by the auditors who are both trying to reach agreement on the final figures. They have indicated that they expect to complete their audits before the end of May in conjunction with the filing of Form 10-Q for the period ending March 31, 2026.

The final adjustments are focused on accounts payable, which are related to the large global Phase III clinical trial underway and the unexpectedly large increase in screening and patient enrollment in Europe in 2024 and 2025.

As previously announced, the Company’s ending cash balance as of March 31, 2026 is approximately $10.5 million, which is unaudited and is subject to change following the completion of the Company’s financial review for Q1 2026.

About FLAMINGO-01 Open Label Phase III Data

More than 1,300 patients have been screened with a current screen rate of approximately 800 patients per year. The 250 patient non-HLA-A*02 arm is now fully enrolled, where all patients received GLSI-100, which is 5 times more treated patients and recurrence rate data than the approximately 50 patients treated in the Phase IIb trial. The Primary Immunization Series (PIS), which includes the first 6 GLSI-100 injections over the first 6 months and is required to reach peak protection, is followed by 5 booster injections given every 6 months to prolong the immune response, thereby providing longer-term protection.

  • In the non-HLA-A*02 arm, a preliminary analysis of recurrence rates after the PIS is completed shows an approximately 70-80% reduction in recurrence rate.
  • This observation is trending similarly to the Phase IIb trial results and hazard ratio where HLA-A*02 patients were treated and where breast cancer recurrences were reduced up to 80% compared to a 20-50% reduction in recurrence rate by other approved products.
  • The immune response at baseline prior to any GLSI-100 treatment, the increasing immune response during the PIS, and the safety profile of non-HLA-A*02 patients is trending similarly to the HLA-A*02 arms of FLAMINGO-01 and to the Phase IIb study.
    • The AACR Meeting 2026 delayed-type-hypersensitivity (DTH) poster can be downloaded here.
    • The frequency of DTH reactions increased by approximately 4x (290%) in the total open-label non-HLA-A*02 population, increasing from 5.2% of the patients experiencing a DTH reaction at baseline, prior to any GLSI-100 administration, to 20.4% of the patients experiencing a DTH reaction in month 4 or month 6 (McNemar, p < 0.001).
    • As reported in Table 1 of the poster, each HLA-A type exhibited more frequent immune reactivity after treatment with GLSI-100 than at baseline with frequency increasing from 100% to 700%.
    • Baseline DTH reaction prior to any treatment suggests that GP2 may be a natural antigen and that GP2 specific T cells may exist in some patients prior to any treatment with GLSI-100. Baseline immune response to GP2 prior to any vaccination with GP2 was also observed in the Phase IIb trial and is being observed in the blinded randomized arms of FLAMINGO-01, where HLA-A*02 only patients are being vaccinated.

Analysis of the open label data from FLAMINGO-01 has been conducted in a manner that maintains the study blind. The open label recurrence rate, immune response, and safety data is based on the patients enrolled to date in FLAMINGO-01 and the data provided by the clinical sites so far, which is not completed or fully reviewed, and is thus preliminary. While comparing any preliminary FLAMINGO-01 data to the Phase IIb clinical trial data may be possible, these preliminary results are not a prediction of future results, and the results at the end of the study may differ.

About GLSI-100 Phase IIb Study

In the prospective, randomized, single-blinded, placebo-controlled, multi-center (16 sites led by MD Anderson Cancer Center) Phase IIb clinical trial of HLA-A*02 breast cancer patients, 46 HER2/neu 3+ over-expressor patients were treated with GLSI-100, and 50 placebo patients were treated with GM-CSF alone. After 5 years of follow-up, there was an 80% or greater reduction in cancer recurrences in the HER2/neu 3+ patients who were treated with GLSI-100, followed, and remained disease free over the first 6 months, which we believe is the time required to reach peak immunity and thus maximum efficacy and protection. The Phase IIb results can be summarized as follows:

  • 80% or greater reduction in metastatic breast cancer recurrence rate over 5 years of follow-up with a peak immune response at 6 months and well-tolerated safety profile.
  • The PIS elicited a potent immune response as measured by local skin tests and immunological assays.

About FLAMINGO-01 and GLSI-100

FLAMINGO-01 (NCT05232916) is a Phase III clinical trial designed to evaluate the safety and efficacy of Fast Track designated GLSI-100 (GP2 + GM-CSF) in HER2 positive breast cancer patients who had residual disease or high-risk pathologic complete response at surgery and who have completed both neoadjuvant and postoperative adjuvant trastuzumab based treatment. The trial is led by Baylor College of Medicine and currently includes US and European clinical sites from university-based hospitals and academic and cooperative networks with plans to open up to 150 sites globally. In the double-blinded arms of the Phase III trial, approximately 500 HLA-A*02 patients are planned to be randomized to GLSI-100 or placebo, and up to 250 patients of other HLA types are planned to be treated with GLSI-100 in a third arm. The trial has been designed to detect a hazard ratio of 0.3 in invasive breast cancer-free survival, where 28 events will be required. An interim analysis for superiority and futility will be conducted when at least half of those events, 14, have occurred. This sample size provides 80% power if the annual rate of events in placebo-treated subjects is 2.4% or greater.

For more information on FLAMINGO-01, please visit the Company’s website here and clinicaltrials.gov here. Contact information and an interactive map of the majority of participating clinical sites can be viewed under the “Contacts and Locations” section. Please note that the interactive map is not viewable on mobile screens. Related questions and participation interest can be emailed to: [email protected]

About Breast Cancer and HER2/neu Positivity

One in eight U.S. women will develop invasive breast cancer over her lifetime, with approximately 300,000 new breast cancer patients and 4 million breast cancer survivors. HER2 (human epidermal growth factor receptor 2) protein is a cell surface receptor protein that is expressed in a variety of common cancers, including in 75% of breast cancers at low (1+), intermediate (2+), and high (3+ or over-expressor) levels.

About Greenwich LifeSciences, Inc.

Greenwich LifeSciences is a clinical-stage biopharmaceutical company focused on the development of GP2, an immunotherapy to prevent breast cancer recurrences in patients who have previously undergone surgery. GP2 is a 9 amino acid transmembrane peptide of the HER2 protein, a cell surface receptor protein that is expressed in a variety of common cancers, including expression in 75% of breast cancers at low (1+), intermediate (2+), and high (3+ or over-expressor) levels. Greenwich LifeSciences has commenced a Phase III clinical trial, FLAMINGO-01. For more information on Greenwich LifeSciences, please visit the Company’s website at www.greenwichlifesciences.com and follow the Company’s Twitter at https://twitter.com/GreenwichLS.

Forward-Looking Statement Disclaimer

Statements in this press release contain “forward-looking statements” that are subject to substantial risks and uncertainties. All statements, other than statements of historical fact, contained in this press release are forward-looking statements. Forward-looking statements contained in this press release may be identified by the use of words such as “anticipate,” “believe,” “contemplate,” “could,” “estimate,” “expect,” “intend,” “seek,” “may,” “might,” “plan,” “potential,” “predict,” “project,” “target,” “aim,” “should,” “will,” “would,” or the negative of these words or other similar expressions, although not all forward-looking statements contain these words. Forward-looking statements are based on Greenwich LifeSciences Inc.’s current expectations and are subject to inherent uncertainties, risks and assumptions that are difficult to predict, including statements regarding the intended use of net proceeds from the public offering; consequently, actual results may differ materially from those expressed or implied by such forward-looking statements. Further, certain forward-looking statements are based on assumptions as to future events that may not prove to be accurate. These and other risks and uncertainties are described more fully in the section entitled “Risk Factors” in Greenwich LifeSciences’ Annual Report on the most recent Form 10-K for the year ended December 31, 2024, and other periodic reports filed with the Securities and Exchange Commission. Forward-looking statements contained in this announcement are made as of this date, and Greenwich LifeSciences, Inc. undertakes no duty to update such information except as required under applicable law.

Company Contact
Snehal Patel
Investor Relations
Office: (832) 819-3232
Email: [email protected]

Investor & Public Relations Contact for Greenwich LifeSciences
Dave Gentry
RedChip Companies Inc.
Office: 1-800-RED CHIP (733 2447)
Email: [email protected]

Primary Logo

Source: Greenwich LifeSciences, Inc.

Released April 30, 2026

Release – Greenwich LifeSciences Announces Acceptance of Abstract at ASCO 2026

Posted on by [email protected]

Research News and Market Data on GLSI

 Download as PDF

April 23, 2026 6:00am EDT

STAFFORD, Texas, April 23, 2026 (GLOBE NEWSWIRE) — Greenwich LifeSciences, Inc. (Nasdaq: GLSI) (the “Company”), a clinical-stage biopharmaceutical company focused on its Phase III clinical trial, FLAMINGO-01, which is evaluating Fast Track designated GLSI-100, an immunotherapy to prevent breast cancer recurrences, today announced that an abstract has been accepted for publication at the upcoming 2026 ASCO Annual Meeting along with a corresponding poster presentation.

The 2026 ASCO Annual Meeting will be held from May 28 to June 2, 2026. The full text of the abstract and poster will be available on June 1, 2026, the day of the presentation.

CEO Snehal Patel commented, ” We look forward to meeting many of our principal investigators at the conference. Our abstract will be the second abstract co-authored by the Company and the full Steering Committee of FLAMINGO-01 presenting preliminary injection site reaction immune response data from the non-HLA-A*02 open-label arm.”

In addition to ASCO, the Company plans to attend ESMO Breast, BIO partnering, and investor conferences in the coming months.

About the 2026 ASCO Annual Meeting

ASCO is the world’s leading professional organization for physicians and oncology professionals caring for people with cancer. ASCO offers premier scientific events for oncology professionals, patient advocates, industry representatives, and major media outlets worldwide. The ASCO Annual Meeting program features poster presentations, poster discussion sessions, clinical science symposia, and dynamic education sessions about recent advancements in cancer research, treatment, and patient care. For more information, please visit the conference website at: https://conferences.asco.org/am/attend.

About FLAMINGO-01 Open Label Phase III Data

More than 1,300 patients have been screened with a current screen rate of approximately 800 patients per year. The 250 patient non-HLA-A*02 arm is now fully enrolled, where all patients received GLSI-100, which is 5 times more treated patients and recurrence rate data than the approximately 50 patients treated in the Phase IIb trial. The Primary Immunization Series (PIS), which includes the first 6 GLSI-100 injections over the first 6 months and is required to reach peak protection, is followed by 5 booster injections given every 6 months to prolong the immune response, thereby providing longer-term protection.

  • In the non-HLA-A*02 arm, a preliminary analysis of recurrence rates after the PIS is completed shows an approximately 70-80% reduction in recurrence rate.
  • This observation is trending similarly to the Phase IIb trial results and hazard ratio where HLA-A*02 patients were treated and where breast cancer recurrences were reduced up to 80% compared to a 20-50% reduction in recurrence rate by other approved products.
  • The immune response at baseline prior to any GLSI-100 treatment, the increasing immune response during the PIS, and the safety profile of non-HLA-A*02 patients is trending similarly to the HLA-A*02 arms of FLAMINGO-01 and to the Phase IIb study.
    • The AACR Meeting 2026 delayed-type-hypersensitivity (DTH) poster can be downloaded here.
    • The frequency of DTH reactions increased by approximately 4x (290%) in the total open-label non-HLA-A*02 population, increasing from 5.2% of the patients experiencing a DTH reaction at baseline, prior to any GLSI-100 administration, to 20.4% of the patients experiencing a DTH reaction in month 4 or month 6 (McNemar, p < 0.001).
    • As reported in Table 1 of the poster, each HLA-A type exhibited more frequent immune reactivity after treatment with GLSI-100 than at baseline with frequency increasing from 100% to 700%.
    • Baseline DTH reaction prior to any treatment suggests that GP2 may be a natural antigen and that GP2 specific T cells may exist in some patients prior to any treatment with GLSI-100. Baseline immune response to GP2 prior to any vaccination with GP2 was also observed in the Phase IIb trial and is being observed in the blinded randomized arms of FLAMINGO-01, where HLA-A*02 only patients are being vaccinated.

Analysis of the open label data from FLAMINGO-01 has been conducted in a manner that maintains the study blind. The open label recurrence rate, immune response, and safety data is based on the patients enrolled to date in FLAMINGO-01 and the data provided by the clinical sites so far, which is not completed or fully reviewed, and is thus preliminary. While comparing any preliminary FLAMINGO-01 data to the Phase IIb clinical trial data may be possible, these preliminary results are not a prediction of future results, and the results at the end of the study may differ.

About GLSI-100 Phase IIb Study

In the prospective, randomized, single-blinded, placebo-controlled, multi-center (16 sites led by MD Anderson Cancer Center) Phase IIb clinical trial of HLA-A*02 breast cancer patients, 46 HER2/neu 3+ over-expressor patients were treated with GLSI-100, and 50 placebo patients were treated with GM-CSF alone. After 5 years of follow-up, there was an 80% or greater reduction in cancer recurrences in the HER2/neu 3+ patients who were treated with GLSI-100, followed, and remained disease free over the first 6 months, which we believe is the time required to reach peak immunity and thus maximum efficacy and protection. The Phase IIb results can be summarized as follows:

  • 80% or greater reduction in metastatic breast cancer recurrence rate over 5 years of follow-up with a peak immune response at 6 months and well-tolerated safety profile.
  • The PIS elicited a potent immune response as measured by local skin tests and immunological assays.

About FLAMINGO-01 and GLSI-100

FLAMINGO-01 (NCT05232916) is a Phase III clinical trial designed to evaluate the safety and efficacy of Fast Track designated GLSI-100 (GP2 + GM-CSF) in HER2 positive breast cancer patients who had residual disease or high-risk pathologic complete response at surgery and who have completed both neoadjuvant and postoperative adjuvant trastuzumab based treatment. The trial is led by Baylor College of Medicine and currently includes US and European clinical sites from university-based hospitals and academic and cooperative networks with plans to open up to 150 sites globally. In the double-blinded arms of the Phase III trial, approximately 500 HLA-A*02 patients are planned to be randomized to GLSI-100 or placebo, and up to 250 patients of other HLA types are planned to be treated with GLSI-100 in a third arm. The trial has been designed to detect a hazard ratio of 0.3 in invasive breast cancer-free survival, where 28 events will be required. An interim analysis for superiority and futility will be conducted when at least half of those events, 14, have occurred. This sample size provides 80% power if the annual rate of events in placebo-treated subjects is 2.4% or greater.

For more information on FLAMINGO-01, please visit the Company’s website here and clinicaltrials.gov here. Contact information and an interactive map of the majority of participating clinical sites can be viewed under the “Contacts and Locations” section. Please note that the interactive map is not viewable on mobile screens. Related questions and participation interest can be emailed to: [email protected]

About Breast Cancer and HER2/neu Positivity

One in eight U.S. women will develop invasive breast cancer over her lifetime, with approximately 300,000 new breast cancer patients and 4 million breast cancer survivors. HER2 (human epidermal growth factor receptor 2) protein is a cell surface receptor protein that is expressed in a variety of common cancers, including in 75% of breast cancers at low (1+), intermediate (2+), and high (3+ or over-expressor) levels.

About Greenwich LifeSciences, Inc.

Greenwich LifeSciences is a clinical-stage biopharmaceutical company focused on the development of GP2, an immunotherapy to prevent breast cancer recurrences in patients who have previously undergone surgery. GP2 is a 9 amino acid transmembrane peptide of the HER2 protein, a cell surface receptor protein that is expressed in a variety of common cancers, including expression in 75% of breast cancers at low (1+), intermediate (2+), and high (3+ or over-expressor) levels. Greenwich LifeSciences has commenced a Phase III clinical trial, FLAMINGO-01. For more information on Greenwich LifeSciences, please visit the Company’s website at www.greenwichlifesciences.com and follow the Company’s Twitter at https://twitter.com/GreenwichLS.

Forward-Looking Statement Disclaimer

Statements in this press release contain “forward-looking statements” that are subject to substantial risks and uncertainties. All statements, other than statements of historical fact, contained in this press release are forward-looking statements. Forward-looking statements contained in this press release may be identified by the use of words such as “anticipate,” “believe,” “contemplate,” “could,” “estimate,” “expect,” “intend,” “seek,” “may,” “might,” “plan,” “potential,” “predict,” “project,” “target,” “aim,” “should,” “will,” “would,” or the negative of these words or other similar expressions, although not all forward-looking statements contain these words. Forward-looking statements are based on Greenwich LifeSciences Inc.’s current expectations and are subject to inherent uncertainties, risks and assumptions that are difficult to predict, including statements regarding the intended use of net proceeds from the public offering; consequently, actual results may differ materially from those expressed or implied by such forward-looking statements. Further, certain forward-looking statements are based on assumptions as to future events that may not prove to be accurate. These and other risks and uncertainties are described more fully in the section entitled “Risk Factors” in Greenwich LifeSciences’ Annual Report on the most recent Form 10-K for the year ended December 31, 2024, and other periodic reports filed with the Securities and Exchange Commission. Forward-looking statements contained in this announcement are made as of this date, and Greenwich LifeSciences, Inc. undertakes no duty to update such information except as required under applicable law.

Company Contact
Snehal Patel
Investor Relations
Office: (832) 819-3232
Email: [email protected]

Investor & Public Relations Contact for Greenwich LifeSciences
Dave Gentry
RedChip Companies Inc.
Office: 1-800-RED CHIP (733 2447)
Email: [email protected]

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Source: Greenwich LifeSciences, Inc.

Released April 23, 2026

Release – Greenwich LifeSciences Announces Receipt of Nasdaq Notice Regarding Late Form 10-K Filing

Posted on by [email protected]
Greenwich LifeSciences

Research News and Market Data on GLSI

 Download as PDF

April 22, 2026 5:00pm EDT

STAFFORD, Texas, April 22, 2026 (GLOBE NEWSWIRE) — Greenwich LifeSciences, Inc. (Nasdaq: GLSI) (the “Company”), a clinical-stage biopharmaceutical company focused on its Phase III clinical trial, FLAMINGO-01, which is evaluating Fast Track designated GLSI-100, an immunotherapy to prevent breast cancer recurrences, today announced that on April 16, 2026, the Company received notification from the Listing Qualifications Department of The Nasdaq Stock Market LLC notifying the Company that, because it has not yet filed its Annual Report on Form 10-K for the fiscal year ended December 31, 2025, the Company is not currently in compliance with Nasdaq Listing Rule 5250(c)(1), which requires timely filing of periodic financial reports with the Securities and Exchange Commission. The notice has no immediate effect on the listing or trading of the Company’s common stock, which continues to trade on the Nasdaq Capital Market under the symbol “GLSI.”

The Company plans to file its Form 10-K for the fiscal year ended December 31, 2025 as soon as possible, working with both of its auditors where each auditor is responsible for their own periods ending in 2024 and 2025.

About Greenwich LifeSciences, Inc.

Greenwich LifeSciences is a clinical-stage biopharmaceutical company focused on the development of GP2, an immunotherapy to prevent breast cancer recurrences in patients who have previously undergone surgery. GP2 is a 9 amino acid transmembrane peptide of the HER2 protein, a cell surface receptor protein that is expressed in a variety of common cancers, including expression in 75% of breast cancers at low (1+), intermediate (2+), and high (3+ or over-expressor) levels. Greenwich LifeSciences has commenced a Phase III clinical trial, FLAMINGO-01. For more information on Greenwich LifeSciences, please visit the Company’s website at www.greenwichlifesciences.com and follow the Company’s Twitter at https://twitter.com/GreenwichLS.

Forward-Looking Statement Disclaimer

Statements in this press release contain “forward-looking statements” that are subject to substantial risks and uncertainties. All statements, other than statements of historical fact, contained in this press release are forward-looking statements. Forward-looking statements contained in this press release may be identified by the use of words such as “anticipate,” “believe,” “contemplate,” “could,” “estimate,” “expect,” “intend,” “seek,” “may,” “might,” “plan,” “potential,” “predict,” “project,” “target,” “aim,” “should,” “will,” “would,” or the negative of these words or other similar expressions, although not all forward-looking statements contain these words. Forward-looking statements are based on Greenwich LifeSciences Inc.’s current expectations and are subject to inherent uncertainties, risks and assumptions that are difficult to predict, including statements regarding the intended use of net proceeds from the public offering; consequently, actual results may differ materially from those expressed or implied by such forward-looking statements. Further, certain forward-looking statements are based on assumptions as to future events that may not prove to be accurate. These and other risks and uncertainties are described more fully in the section entitled “Risk Factors” in Greenwich LifeSciences’ Annual Report on the most recent Form 10-K for the year ended December 31, 2024, and other periodic reports filed with the Securities and Exchange Commission. Forward-looking statements contained in this announcement are made as of this date, and Greenwich LifeSciences, Inc. undertakes no duty to update such information except as required under applicable law.

Company Contact
Snehal Patel
Investor Relations
Office: (832) 819-3232
Email: [email protected]

Investor & Public Relations Contact for Greenwich LifeSciences
Dave Gentry
RedChip Companies Inc.
Office: 1-800-RED CHIP (733 2447)
Email: [email protected]

Primary Logo

Source: Greenwich LifeSciences, Inc.

Released April 22, 2026

Greenwich LifeSciences, Inc. (GLSI) – Preliminary FLAMINGO-01 Data Presented At AACR

Posted on by [email protected]


Wednesday, April 22, 2026

Robert LeBoyer, Senior Vice President, Equity Research Analyst, Biotechnology, Noble Capital Markets, Inc.

Refer to the full report for the price target, fundamental analysis, and rating.

Phase 3 FLAMINGO-01 Data Presented. Greenwich LifeSciences and the FLAMINGO-01 Steering Committee made two presentations at the American Association of Cancer Research (AACR) 2026 Meeting. One detailed the FLAMINGO-01 trial design while the other presented preliminary results from delayed-type hypersensitivity (DTH) response data showing a statistically significant immune response.

First Poster Presentation Included DTH Data. As discussed in our Research Note on March 18, the company announced a preliminary analysis of recurrence rates in the non-HLA-A*02 arm. Immune responses to GP2 were measured using Delayed-Type Hypersensitivity (DTH) skin tests at baseline, then after 4 or 6 months. This open-label arm of the trial has enrolled about 250 patients, with data reported for 191 patients who completed the six-monthly doses of GLSI-100 at four-month or six-month evaluation points.


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Release – Greenwich LifeSciences Presents FLAMINGO-01 Phase III Trial Open Label Data Published at AACR Meeting 2026

Posted on by [email protected]

Research News and Market Data on GLSI

 Download as PDF April 20, 2026 6:00am EDT

STAFFORD, Texas, April 20, 2026 (GLOBE NEWSWIRE) — Greenwich LifeSciences, Inc. (Nasdaq: GLSI) (the “Company”), a clinical-stage biopharmaceutical company focused on its Phase III clinical trial, FLAMINGO-01, which is evaluating Fast Track designated GLSI-100, an immunotherapy to prevent breast cancer recurrences, today presents the published abstract and poster from the AACR Meeting 2026.

The abstract is shown below and the poster being presented today can be seen and downloaded at the bottom of Phase III clinical trial tab on the Company’s website here.

  • This is the first abstract and poster presented jointly with the Steering Committee of FLAMINGO-01 with statistically significant delayed-type-hypersensitivity (DTH) immune response data, with subgroup analysis by the most prevalent HLA types.
  • In the non-HLA-A*02 open label arm where all patients (n=247) were treated with GLSI-100, immune responses to GP2 were measured at baseline and over time using skin tests and other methods. The other methods will be presented at a future conference.
  • A DTH reaction (redness and/or induration) was used to assess in vivo immune responses in patients. The DTH orthogonal mean was also measured 48-72 hours after injection but is not reported here.
  • In this preliminary data analysis, there was a significant increase in percentage of patients experiencing a DTH reaction (redness) in month 4 or month 6 compared to baseline. There were 191 patients with both baseline and month 4 or 6 assessments.
  • The frequency of DTH reactions increased by approximately 4x (290%) in the total open-label non-HLA-A*02 population, increasing from 5.2% of the patients experiencing a DTH reaction at baseline, prior to any GLSI-100 administration, to 20.4% of the patients experiencing a DTH reaction in month 4 or month 6 (McNemar, p < 0.001).
  • As reported in Table 1 of the poster, each HLA-A type exhibited more frequent immune reactivity after treatment with GLSI-100 than at baseline with frequency increasing from 100% to 700%. 
  • Baseline DTH reaction prior to any treatment suggests that GP2 may be a natural antigen and that GP2 specific T cells may exist in some patients prior to any treatment with GLSI-100. Baseline immune response to GP2 prior to any vaccination with GP2 was also observed in the Phase IIb trial and is being observed in the blinded randomized arms of FLAMINGO-01, where HLA-A*02 only patients are being vaccinated.
  • Mechanism of Action: A positive immune response is an indicator that the immune system has been activated against recurring cancer cells, potentially leading to the prevention of metastatic breast cancer. The Company previously announced that in the non-HLA-A*02 arm, a preliminary analysis of recurrence rates after the Primary Immunization Series (PIS) is completed shows an approximately 70-80% reduction in recurrence rate. Thus, the immune response data is supporting the mechanism of action that reduces recurrences and prevents metastatic breast cancer.
  • This statistically significant non-HLA-A*02 open label arm immune response data is trending similarly to the immune response data in the HLA-A*02 patients in the Phase IIb study and the HLA-A*02 arms of FLAMINGO-01. The study is ongoing and data collection and cleaning continue, while some patients may still be in their PIS vaccination phase, so final results may vary.
  • A 1% per year recurrence rate is so low that the number of recurrence events is too few to correlate a negative or lack of immune response to recurrence. The same constraint existed with the Phase IIb data which has a similarly low recurrence rate per year. While DTH immune response may be valuable at an aggregate level looking at whole patient populations, the recurrence rate is too low to validate any immune response measure as a biomarker for individual patient treatment decisions. It is also likely that some responding patients may not exhibit any immune response but still could be protected by GLSI-100 vaccination, thus helping to preserve the blind on the randomized arms of FLAMINGO-01.

The immune response abstract and poster conclusion: The statistically significant increase in the incidence of DTH reactions over time found in this preliminary analysis of GLSI-100 treated non-HLA-A*02 patients shows that GLSI-100 treatment should not be limited to HLA-A*02 patients. Patients treated with GLSI-100 were increasingly able to mount an immune response to GP2 as evidenced in this preliminary data. Future investigations may explore the use of immune responses to assess correlation of DTH to ISRs, immunogenicity of GLSI-100 by specific HLA type, timing of boosters to sustain immunity, clinical site performance, and the discontinuation of treatment for non-responders.

In addition, the second poster describing the Phase III trial design, which is being presented on Tuesday, April 21, can be downloaded and seen on the website using the same link. This poster provides an update that over 1,300 patients have been screened to date in FLAMINGO-01. The new protocol amendment, which is still under regulatory review in certain countries, is not discussed.

CEO Snehal Patel commented, “This new immune response data further supports the combination of HLA-A*02 and non-HLA-A*02 patients in the same randomized arms. In the US, the FDA recently reviewed such protocol changes and the many non-HLA-A*02 patients on waiting lists that were previously screened are now being enrolled. The screen rate continues to be encouraging, reflecting the high patient interest in the study as we have now screened over 1,300 patients. The Company will have the option to pursue approval for both HLA-A*02 and non-HLA-A*02 patients together using the increased statistical power of a combined analysis of the two patient groups or to pursue subgroups based on planned multiple interim analyses.”

The abstract from today’s immune response data and the members of the Steering Committee follow:

Abstract Number: CT138 – Poster Section 52 on April 20, 2026, 2-5pm PT

Abstract Title: Preliminary delayed-type-hypersensitivity immune response results from open-label arm of on-going Phase III study to evaluate the efficacy and safety of GLSI-100 (GP2 + GM-CSF) in breast cancer patients with residual disease or high-risk PCR after both neo-adjuvant and postoperative adjuvant anti-HER2 therapy, Flamingo-01

Snehal S. Patel1, Jaye Thompson1, F. Joseph Daugherty1, Francois-Clement Bidard2, William J. Gradishar3, Marcus Schmidt4, Miguel Martin5, Joyce A. O’Shaughnessy6, Hope S. Rugo7, Cesar A. Santa-Maria8, Laura M. Spring9, Mothaffar F. Rimawi10

1Greenwich LifeSciences, Stafford, TX,2Institut Curie, Paris, France,3Northwestern University, Chicago, IL,4University Medical Center Mainz, Mainz, Germany,5GEICAM, Madrid, Spain,6Sarah Cannon Research Institute, Dallas, TX,7City of Hope Comprehensive Cancer Center, Duarte, CA,8Johns Hopkins University, Baltimore, MD,9Massachusetts General Hospital, Boston, MA,10Lester and Sue Smith Breast Center, Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX

Background: This Phase III trial is a prospective, randomized, double-blinded, multi-center study (NCT05232916) in HLA-A*02 patients at approximately 140 sites in the US and Europe. A third non-randomized arm of approximately 250 non-HLA-A*02 patients is now fully enrolled and preliminary immune response data is presented below. GP2 is a biologic nine amino acid peptide of the HER2/neu protein delivered in combination with Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) that stimulates an immune response targeting HER2/neu expressing cancers, the combination known as GLSI-100.

Methods: After standard of care neoadjuvant and adjuvant therapy, 6 intradermal injections of GLSI-100 will be administered over the first 6 months and 5 subsequent boosters will be administered over the next 2.5 years. The participant duration of the trial will be 3 years treatment plus 1 additional year follow-up. Immune responses to GP2 were measured over time using delayed-type-hypersensitivity (DTH) skin tests and injection site reactions (ISRs). The patient population is defined by these key eligibility criteria: 1) HER2/neu positive and HLA, 2) Residual disease or High risk pCR (Stage III at presentation) post neo-adjuvant therapy, 3) Exclude Stage IV, and 4) Completed at least 90% of planned trastuzumab-based therapy.

Results: All patients (n=247) were vaccinated with GLSI-100 and continue in treatment and follow-up. A DTH reaction (redness) was used to assess in vivo immune responses in patients. The DTH orthogonal mean was measured 48-72 hours after injection. In this preliminary data analysis, there was a significant increase in percentage of subjects experiencing a DTH reaction in month 4 or month 6 compared to baseline. The frequency of DTH reactions increased by approximately 4x from 5.2% of the patients experiencing a DTH reaction at baseline, prior to any GLSI-100 administration, to 20.4% of the patients experiencing a DTH reaction in month 4 or month 6 (McNemar, p < 0.001). The study is ongoing and data collection and cleaning continue so final results may vary.

Conclusions: The increase in the incidence of DTH reactions over time found in this preliminary analysis of GLSI-100 treated non-HLA-A*02 patients shows that GLSI-100 treatment should not be limited to the HLA-A*02 genotype. Subjects treated with GLSI-100 were increasingly able to mount an immune response to GP2 as evidenced in this preliminary data. Future investigations may explore the use of immune responses to assess: correlation of DTH to ISRs, immunogenicity of GLSI-100 by specific HLA type, timing of boosters to sustain immunity, clinical site performance, and the discontinuation of treatment for non-responders.

The Steering Committee authoring abstract CT138 is comprised of the following experts in the field of breast cancer oncology representing prominent teaching hospitals in the US and 4 of the largest breast oncology networks in the US, Germany, France, and Spain:

  • Dr. Mothaffar F. Rimawi – Professor of Medicine at the Baylor College of Medicine and Executive Medical Director and Co-Leader, Breast Cancer Program of the Dan L Duncan Comprehensive Cancer Center
  • Dr. Francois-Clement Bidard – Professor of Medical Oncology, UVSQ/Paris Saclay University, Head of Breast Cancer Group, Institut Curie, Vice-Chair of the French Breast Cancer research group UCBG (Unicancer)
  • Dr. William J. Gradishar – Professor of Medicine at the Feinberg School of Medicine at Northwestern University, Chief of Hematology and Oncology in the Department of Medicine, and Betsy Bramsen Professor of Breast Oncology
  • Dr. Sibylle Loibl – Professor (apl) Goethe University Frankfurt/M, Clinical Consultant Centre for Haematology and Oncology/Bethanien Frankfurt/M, CEO of GBG Forschungs GmbH & Chair of the German Breast Group (GBG)
  • Dr. Miguel Martin – Professor of Medicine, Head, Medical Oncology Service, Gregorio Marañón General University Hospital, Complutense University, Madrid, CEO of GEICAM
  • Dr. Joyce A. O’Shaughnessy – Celebrating Women Chair in Breast Cancer, Baylor University Medical Center and Chair, Breast Cancer Program, Texas Oncology, US Oncology, Dallas, Texas
  • Dr. Hope S. Rugo – Director, Women’s Cancers Program, Division Chief, Breast Medical Oncology, Professor, Department of Medical Oncology & Therapeutics Research, City of Hope Comprehensive Cancer Center, Professor Emeritus, University of California, San Francisco
  • Dr. Cesar A. Santa-Maria – Associate Professor of Oncology, Breast and Gynecological Malignancies Group, Director of Breast Cancer Trials, Johns Hopkins Sidney Kimmel Comprehensive Cancer Center
  • Dr. Laura M. Spring – Assistant Professor, Medicine, Harvard Medical School, Attending Physician, Medical Oncology, Massachusetts General Hospital

About the AACR Annual Meeting 2026

The AACR is the first and largest cancer research organization dedicated to accelerating the conquest of cancer and has more than 61,000 members residing in 143 countries and territories. The AACR Annual Meeting is the focal point of the cancer research community, where scientists, clinicians, other health care professionals, survivors, patients, and advocates gather to share the latest advances in cancer science and medicine. From population science and prevention; to cancer biology, translational, and clinical studies; to survivorship and advocacy; the AACR Annual Meeting highlights the work of the best minds in cancer research from institutions all over the world.

About FLAMINGO-01 Open Label Phase III Data
More than 1,000 patients have been screened with a current screen rate of approximately 800 patients per year. The 250 patient non-HLA-A*02 arm is now fully enrolled, where all patients received GLSI-100, which is 5 times more treated patients and recurrence rate data than the approximately 50 patients treated in the Phase IIb trial. The Primary Immunization Series (PIS), which includes the first 6 GLSI-100 injections over the first 6 months and is required to reach peak protection, is followed by 5 booster injections given every 6 months to prolong the immune response, thereby providing longer-term protection.

  • In the non-HLA-A*02 arm, a preliminary analysis of recurrence rates after the PIS is completed shows an approximately 70-80% reduction in recurrence rate.
  • This observation is trending similarly to the Phase IIb trial results and hazard ratio where HLA-A*02 patients were treated and where breast cancer recurrences were reduced up to 80% compared to a 20-50% reduction in recurrence rate by other approved products.
  • The immune response at baseline prior to any GLSI-100 treatment, the increasing immune response during the PIS, and the safety profile of non-HLA-A*02 patients is trending similarly to the HLA-A*02 arms of FLAMINGO-01 and to the Phase IIb study. 

Analysis of the open label data from FLAMINGO-01 has been conducted in a manner that maintains the study blind. The open label recurrence rate, immune response, and safety data is based on the patients enrolled to date in FLAMINGO-01 and the data provided by the clinical sites so far, which is not completed or fully reviewed, and is thus preliminary. While comparing any preliminary FLAMINGO-01 data to the Phase IIb clinical trial data may be possible, these preliminary results are not a prediction of future results, and the results at the end of the study may differ.

About GLSI-100 Phase IIb Study

In the prospective, randomized, single-blinded, placebo-controlled, multi-center (16 sites led by MD Anderson Cancer Center) Phase IIb clinical trial of HLA-A*02 breast cancer patients, 46 HER2/neu 3+ over-expressor patients were treated with GLSI-100, and 50 placebo patients were treated with GM-CSF alone. After 5 years of follow-up, there was an 80% or greater reduction in cancer recurrences in the HER2/neu 3+ patients who were treated with GLSI-100, followed, and remained disease free over the first 6 months, which we believe is the time required to reach peak immunity and thus maximum efficacy and protection. The Phase IIb results can be summarized as follows:

  • 80% or greater reduction in metastatic breast cancer recurrence rate over 5 years of follow-up with a peak immune response at 6 months and well-tolerated safety profile.
  • The PIS elicited a potent immune response as measured by local skin tests and immunological assays.

About FLAMINGO-01 and GLSI-100

FLAMINGO-01 (NCT05232916) is a Phase III clinical trial designed to evaluate the safety and efficacy of Fast Track designated GLSI-100 (GP2 + GM-CSF) in HER2 positive breast cancer patients who had residual disease or high-risk pathologic complete response at surgery and who have completed both neoadjuvant and postoperative adjuvant trastuzumab based treatment. The trial is led by Baylor College of Medicine and currently includes US and European clinical sites from university-based hospitals and academic and cooperative networks with plans to open up to 150 sites globally. In the double-blinded arms of the Phase III trial, approximately 500 HLA-A*02 patients are planned to be randomized to GLSI-100 or placebo, and up to 250 patients of other HLA types are planned to be treated with GLSI-100 in a third arm. The trial has been designed to detect a hazard ratio of 0.3 in invasive breast cancer-free survival, where 28 events will be required. An interim analysis for superiority and futility will be conducted when at least half of those events, 14, have occurred. This sample size provides 80% power if the annual rate of events in placebo-treated subjects is 2.4% or greater.

For more information on FLAMINGO-01, please visit the Company’s website here and clinicaltrials.gov here. Contact information and an interactive map of the majority of participating clinical sites can be viewed under the “Contacts and Locations” section. Please note that the interactive map is not viewable on mobile screens. Related questions and participation interest can be emailed to: [email protected]

About Breast Cancer and HER2/neu Positivity

One in eight U.S. women will develop invasive breast cancer over her lifetime, with approximately 300,000 new breast cancer patients and 4 million breast cancer survivors. HER2 (human epidermal growth factor receptor 2) protein is a cell surface receptor protein that is expressed in a variety of common cancers, including in 75% of breast cancers at low (1+), intermediate (2+), and high (3+ or over-expressor) levels.

About Greenwich LifeSciences, Inc.

Greenwich LifeSciences is a clinical-stage biopharmaceutical company focused on the development of GP2, an immunotherapy to prevent breast cancer recurrences in patients who have previously undergone surgery. GP2 is a 9 amino acid transmembrane peptide of the HER2 protein, a cell surface receptor protein that is expressed in a variety of common cancers, including expression in 75% of breast cancers at low (1+), intermediate (2+), and high (3+ or over-expressor) levels. Greenwich LifeSciences has commenced a Phase III clinical trial, FLAMINGO-01. For more information on Greenwich LifeSciences, please visit the Company’s website at www.greenwichlifesciences.com and follow the Company’s Twitter at https://twitter.com/GreenwichLS.

Forward-Looking Statement Disclaimer

Statements in this press release contain “forward-looking statements” that are subject to substantial risks and uncertainties. All statements, other than statements of historical fact, contained in this press release are forward-looking statements. Forward-looking statements contained in this press release may be identified by the use of words such as “anticipate,” “believe,” “contemplate,” “could,” “estimate,” “expect,” “intend,” “seek,” “may,” “might,” “plan,” “potential,” “predict,” “project,” “target,” “aim,” “should,” “will,” “would,” or the negative of these words or other similar expressions, although not all forward-looking statements contain these words. Forward-looking statements are based on Greenwich LifeSciences Inc.’s current expectations and are subject to inherent uncertainties, risks and assumptions that are difficult to predict, including statements regarding the intended use of net proceeds from the public offering; consequently, actual results may differ materially from those expressed or implied by such forward-looking statements. Further, certain forward-looking statements are based on assumptions as to future events that may not prove to be accurate. These and other risks and uncertainties are described more fully in the section entitled “Risk Factors” in Greenwich LifeSciences’ Annual Report on the most recent Form 10-K for the year ended December 31, 2024, and other periodic reports filed with the Securities and Exchange Commission. Forward-looking statements contained in this announcement are made as of this date, and Greenwich LifeSciences, Inc. undertakes no duty to update such information except as required under applicable law.

Company Contact
Snehal Patel
Investor Relations
Office: (832) 819-3232
Email: [email protected]

Investor & Public Relations Contact for Greenwich LifeSciences
Dave Gentry
RedChip Companies Inc.
Office: 1-800-RED CHIP (733 2447)
Email: [email protected]

Primary Logo

Source: Greenwich LifeSciences, Inc.

Released April 20, 2026