Greenwich LifeSciences Provides Clinical Updates on FLAMINGO-01
Rhea-AI Summary
Greenwich LifeSciences (Nasdaq: GLSI) reported multiple clinical and financial updates on its Phase III breast cancer trial FLAMINGO-01 evaluating GLSI-100. The May 2026 Data Safety Monitoring Board recommended the study continue unchanged. Following FDA and EMA review, the trial design has been expanded and amended, including combining all HLA types in the blinded arms, which is expected to increase enrollment 2.22x by allowing non-HLA-A*02 patients (about 55% of the population) to enter randomization.
The company has screened over 1,500 patients across roughly 170-180 sites in 11 countries and fully enrolled the 250-patient non-HLA-A*02 open-label arm. Preliminary analysis after the primary immunization series suggests a 70-80% reduction in recurrence rate (hazard ratio 0.2-0.3). Trial redesign targets a hazard ratio of 0.55 with up to 2,000 patients and interim analyses at 28 and 56 events. Greenwich reported an annual cash burn of about $7 million in 2023-2024, $10 million in 2025, and expects approximately $2 million burn in Q2 2026, with an estimated June 30, 2026 cash balance of $8.9 million; these financial figures are preliminary and unaudited.
Positive
- DSMB supports continuation of FLAMINGO-01 without modification after May 2026 review
- Enrollment rate projected to increase 2.22x by including non-HLA-A*02 patients in blinded arms
- Over 1,500 patients screened across approximately 170-180 sites in 11 countries
- 250-patient non-HLA-A*02 arm fully enrolled with preliminary 70-80% recurrence reduction (HR ≈0.2-0.3)
- Annual cash burn about $7M in 2023-2024 and $10M in 2025 with internalized operations
- Q2 2026 burn expected at ~$2M and cash balance around $8.9M, per preliminary estimates
Negative
- Annual burn rate increased to about $10M in 2025 from ~$7M in prior years
- Q2 2026 financial figures are unaudited and subject to change after review
- Open-label efficacy and immune data are preliminary, incomplete, and may differ from final FLAMINGO-01 results
Market reaction after Phase III clinical data: GLSI -13.79% in the Jul 20 session
In the Jul 20 session, GLSI declined 13.79%, reflecting a significant negative market reaction. Argus tracked a trough of -23.5% from its starting point during tracking. Our momentum scanner triggered 24 alerts that day, indicating elevated trading interest and price volatility. Trading volume was very high at 3.4x the daily average, suggesting heavy selling pressure.
Data tracked by StockTitan Argus on the day of publication.
Key Figures
Historical Context
| Date | Event | Sentiment | 24h Move | Catalyst |
|---|---|---|---|---|
| Jul 16 | European trial approval | Positive | -2.7% | EMA approved combining HLA-A*02 and non-HLA-A*02 patients in FLAMINGO-01 randomized arms |
| Jul 09 | Commercial product approval | Positive | +3.7% | EMA approved commercially manufactured GP2 for use in the Phase III FLAMINGO-01 trial |
| Jun 01 | Phase III clinical data | Positive | +8.9% | Open-label immune response data from the non-HLA-A*02 FLAMINGO-01 arm was presented |
| Jun 01 | Annual filing update | Negative | +8.9% | Delayed Form 10-K update disclosed cash, accounting, and continuing funding considerations |
| May 22 | Nasdaq compliance notice | Negative | -0.9% | Nasdaq notice cited noncompliance related to the late Q1 2026 Form 10-Q filing |
24h Move is the share-price change in the day after each event; other market factors may also have contributed.
GLSI's prior clinical and regulatory announcements produced mixed reactions, with favorable trial-related news sometimes followed by both gains and declines.
Key Terms
data safety monitoring board medical
hazard ratio medical
HLA-A*02 medical
delayed-type-hypersensitivity medical
AI-generated analysis. How Rhea-AI works. Not financial advice.
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
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
For the second quarter of 2026, the burn rate is expected to be approximately
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
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
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
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
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.
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- 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 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: flamingo-01@greenwichlifesciences.com
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
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
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: info@greenwichlifesciences.com
Investor & Public Relations Contact for Greenwich LifeSciences
Dave Gentry
RedChip Companies Inc.
Office: 1-800-RED CHIP (733 2447)
Email: dave@redchip.com
