Greenwich LifeSciences Announces Acceptance of Abstract at ASCO 2026
Rhea-AI Summary
Greenwich LifeSciences (Nasdaq: GLSI) announced that an abstract has been accepted for publication and poster presentation at the 2026 ASCO Annual Meeting, May 28–June 2, 2026. The full abstract and poster will be available on June 1, 2026. The submission presents preliminary injection site reaction immune response data from the non-HLA-A*02 open-label arm of Phase III FLAMINGO-01 evaluating Fast Track designated GLSI-100. Management said the abstract is co-authored with the FLAMINGO-01 Steering Committee. The company also plans to attend upcoming ESMO Breast, BIO partnering, and investor conferences.
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News Market Reaction – GLSI
In the Apr 23 session, GLSI declined 5.09%, reflecting a notable negative market reaction.
Data tracked by StockTitan Argus on the day of publication.
Key Figures
Historical Context
| Date | Event | Sentiment | 24h Move | Catalyst |
|---|---|---|---|---|
| Apr 20 | Clinical data update | Positive | -11.6% | Presented Phase III FLAMINGO-01 open-label immune response data at AACR 2026. |
| Apr 14 | Financing update | Positive | -5.3% | ATM sales raised cash above Q1 2026 burn, cash balance about $10.5M. |
| Apr 7 | Patent expansion news | Positive | +2.2% | Patent claims could expand GP2 market by 100% to 88,000 patients/year. |
| Mar 19 | Site expansion | Positive | -3.1% | Added City of Hope sites, potentially lifting FLAMINGO-01 locations from 160 to 190–200. |
| Mar 18 | Conference abstracts | Positive | -11.1% | Announced two AACR 2026 abstracts/posters with Phase III FLAMINGO-01 immune-response data. |
24h Move is the share-price change in the day after each event; other market factors may also have contributed.
Recent positive clinical and corporate updates often saw negative price reactions, with only one of five events aligning positively with the news.
Over the past months, GLSI has repeatedly highlighted progress in its FLAMINGO-01 Phase III program and related initiatives. On Mar 18 and Apr 20, 2026, statistically significant immune-response data and AACR presentations were followed by -11.11% and -11.61% moves. A financing strategy update on Apr 14, 2026 supporting trial costs saw a -5.35% reaction. In contrast, a patent update on Apr 7, 2026 that could double market potential coincided with a modest +2.18% gain.
Key Terms
immunotherapy medical
phase iii medical
fast track regulatory
AI-generated analysis. How Rhea-AI works. Not financial advice.
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 from5.2% of the patients experiencing a DTH reaction at baseline, prior to any GLSI-100 administration, to20.4% 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% to700% . - 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 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
