Greenwich LifeSciences Announces Completion of Enrollment in the Open Label Arm of FLAMINGO-01
Rhea-AI Summary
Greenwich LifeSciences (Nasdaq: GLSI) announced completion of enrollment in the 250-patient open-label non-HLA-A*02 arm of its Phase III FLAMINGO-01 trial of GLSI-100 to prevent breast cancer recurrence on Dec 8, 2025. The company said non-HLA-A*02 patients represent about 55% of the trial population and about 250 non-HLA-A*02 patients have now been treated. Approximately 500 HLA-A*02 patients remain planned for randomization to GLSI-100 or placebo. Greenwich is reviewing immune response, safety, and recurrence-rate data from the 250-patient cohort and may seek regulatory approval to resume randomized enrollment of non-HLA-A*02 patients. The company reiterated prior Phase IIb comparisons and cited patent and market-potential estimates.
Positive
- 250 patients enrolled in open-label non-HLA-A*02 arm
- Non-HLA-A*02 cohort represents ~55% of FLAMINGO-01
- Open-label cohort is ~5x larger than Phase IIb (~50 patients)
- Planned 500 HLA-A*02 patients for randomized arms remain active
Negative
- Non-HLA-A*02 arm is open-label without a randomized control
- Enrollment in non-HLA-A*02 paused pending regulatory approval to randomize
- Recurrence comparisons rely on historical rates and non-randomized data
Key Figures
Market Reality Check
Peers on Argus
Peers show mixed moves: THTX +0.89%, ACOG +1.56%, CHRS -4%, CLYM 0%, MCRB -6.3%. The modest +1.59% move in GLSI appears more stock-specific than sector-driven.
Historical Context
| Date | Event | Sentiment | Move | Catalyst |
|---|---|---|---|---|
| Dec 03 | Trial enrollment update | Positive | +5.1% | Reported >1,000 patients screened and 140 active sites for FLAMINGO-01. |
| Oct 09 | Country expansion | Positive | -2.3% | Added Austria to FLAMINGO-01 following European regulatory approval. |
| Oct 02 | Country expansion | Positive | +5.3% | Expanded FLAMINGO-01 to Belgium, the tenth approved country for the trial. |
| Sep 30 | Country expansion | Positive | -2.1% | Received regulatory approval to expand Phase III FLAMINGO-01 to Portugal. |
| Sep 18 | Country expansion | Positive | +3.5% | Announced expansion of FLAMINGO-01 to Ireland after regulatory approval. |
Recent FLAMINGO-01 updates and country expansions often saw positive but variable price reactions, with some divergence despite constructive trial progress.
Over the past several months, Greenwich LifeSciences has focused news flow on the Phase III FLAMINGO-01 trial of GLSI-100. Updates included multiple European expansions (Ireland, Portugal, Belgium, Austria) and, most recently on Dec 03, a global update noting screening of over 1,000 patients across 140 sites. Price reactions to these trial and geographic expansion milestones have alternated between gains and pullbacks, suggesting investor sensitivity to execution details and financing backdrop as enrollment progresses.
Market Pulse Summary
This announcement highlights completion of enrollment in the 250-patient non-HLA-A*02 open-label arm of FLAMINGO-01, potentially expanding GLSI-100’s reach to about 88,000 new patients per year with prior Phase IIb data suggesting up to 80% recurrence reduction. Recent country expansions and steady screening underpin trial momentum. Offsetting this, the latest 10-Q disclosed a Q3 net loss of $4.15M and cash of $3.81M, making financing and trial execution key metrics to monitor.
Key Terms
neoadjuvant medical
AI-generated analysis. Not financial advice.
STAFFORD, Texas, Dec. 08, 2025 (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 completion of enrollment in the open label non-HLA-A*02 arm of FLAMINGO-01.
In the double-blinded arms of the Phase III trial, approximately 500 HLA-A*02 patients are currently planned to be randomized to GLSI-100 or placebo, and up to 250 patients of other HLA types (non-HLA-A*02) are planned to be treated with GLSI-100 in a third open label arm. The non-HLA-A*02 patients do not have the HLA-A*02 allele from either parent and represent about
- FLAMINGO-01 has achieved a major milestone by completing enrollment in the 250 patient open label non-HLA-A*02 arm of the Phase III trial, which is a result of the high screen rate and ensuing enrollment rate. The Company is continuing its review of the most recent data of this arm, including recurrence rates, which can be updated and/or published at any time.
- The Company stopped enrolling in this arm earlier this year and is now approaching regulatory agencies to seek approval to continue enrollment of new non-HLA-A*02 patients in a randomized manner with a control arm. The Company has continued to screen a large number of these patients so that rapid enrollment of these screened patients can commence if regulatory approval is received.
- The Company previously reported promising observations earlier this year showing that the immune response at baseline prior to any GLSI-100 treatment, the increasing immune response during the primary immunization series, 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, where breast cancer recurrences were reduced up to
80% or more and no metastatic breast cancer recurrences were reported. A preliminary analysis suggests that these promising trends are continuing.
CEO Snehal Patel commented, "As we continue to analyze the immune response, safety, and recurrence rate data of the 250 patient non-HLA-A*02 data set, it is important to remember that all 250 patients received GLSI-100, which is 5 times more than the approximately 50 patients treated in the Phase IIb trial. We can compare the open label recurrence rate data of these 250 treated patients to the expected historical recurrence rate for this population, which is well known and recently reported, to the HLA-A*02 arms of FLAMINGO-01, and to the Phase IIb study. In addition, we may be able to compare the recurrence rate during the first 6 months of vaccination, also called the primary immunization series or PIS, to the recurrence rate after the PIS is completed and after peak immunity is achieved. We look forward to providing updates on this analysis at any time, including publications at conferences as we have previously done for the Phase IIb trial from 2020-2022."
Mr. Patel added, "The use of GLSI-100 in the non-HLA-A*02 patient population is an invention by the Company, and the Company believes that any patent claims related to this invention are not subject to any license, royalties, or milestone payments. These patent claims should complement other patent claims that the Company has recently filed to potentially extend patent protection of GLSI-100 beyond 2040. The Company believes that this patient population could double the number of US and European patients eligible for GLSI-100 treatment to approximately 88,000 new patients per year with a market potential using the drug prices per year of Kadcyla or Enhertu in the range of
Additional updates:
- The non-HLA-A*02 types that are most commonly being enrolled in FLAMINGO-01 continue to be HLA-A*03, HLA-A*24, HLA-A*01, HLA-A*11, HLA-A*68, HLA-A*29, HLA-A*30, HLA-A*23, and HLA-A*33.
- The enrollment of HLA-A*02 patients in the 500 patient randomized arms continues, unaffected by the end of enrollment in the non-HLA-A*02 arm, while the Company also seeks to increase the size of these HLA-A*02 arms such that enrollment is not stopped prior to any interim analyses.
- Enhertu (trastuzumab Deruxtecan [T-DXd]) treated patients continue to be eligible for enrollment in FLAMINGO-01. The Company believes that GLSI-100 will synergize with any trastuzumab based treatment in the neoadjuvant or adjuvant settings, including Enhertu.
About FLAMINGO-01 and GLSI-100
FLAMINGO-01 (NCT05232916) is a Phase III clinical trial designed to evaluate the safety and efficacy of 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
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, 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
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, 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: 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
FAQ
What did Greenwich LifeSciences announce about FLAMINGO-01 on Dec 8, 2025 (GLSI)?
How many HLA-A*02 and non-HLA-A*02 patients are planned in FLAMINGO-01 (GLSI)?
What data is Greenwich reviewing from the 250 non-HLA-A*02 GLSI patients (GLSI)?
Will Greenwich randomize non-HLA-A*02 patients in FLAMINGO-01 (GLSI)?
How does the 250-patient non-HLA-A*02 dataset compare with the Phase IIb GLSI-100 trial (GLSI)?
Does the FLAMINGO-01 trial allow patients previously treated with Enhertu (GLSI)?
