Greenwich LifeSciences Provides Update on Upcoming AACR Meeting
Rhea-AI Summary
Greenwich LifeSciences (Nasdaq: GLSI) announced two accepted abstracts/posters for AACR Meeting 2026, including a FLAMINGO-01 poster (CT138) on April 20, 2026 with statistically significant delayed-type-hypersensitivity (DTH) immune response data from the open-label arm. A second poster (CT227) on April 21, 2026 updates the Phase III study design.
The update highlights Fast Track designated GLSI-100 (GP2 + GM-CSF) being evaluated in breast cancer patients with residual disease or high-risk PCR after anti-HER2 therapy.
Positive
- First statistically significant DTH immune response data reported
- Two posters accepted for AACR Meeting 2026 (April 20–21, 2026)
- GLSI-100 holds Fast Track designation
- Phase III FLAMINGO-01 continues enrollment and investigator updates
Negative
- Immune response data are preliminary and immunologic, not clinical efficacy
- Open-label arm may introduce potential bias in immune readouts
- No survival or recurrence endpoint results disclosed
Key Figures
Market Reality Check
Peers on Argus
GLSI gained 6.83% with strong volume, while key biotech peers showed relatively modest mixed moves (e.g., THTX 0.89%, MCRB 4.28%, CLYM -0.14%), suggesting a stock-specific reaction to the AACR update.
Historical Context
| Date | Event | Sentiment | Move | Catalyst |
|---|---|---|---|---|
| Mar 17 | Recurrence-rate update | Positive | +6.8% | Preliminary data showing markedly reduced recurrence rate in open-label FLAMINGO-01 arm. |
| Mar 16 | Commercial GP2 supply | Positive | +8.4% | FDA approval of first commercial GP2 lot and supply to ~40 US sites. |
| Mar 03 | Screening-rate increase | Positive | -0.5% | Higher FLAMINGO-01 screening rate to over 800 patients annually across US/EU sites. |
| Feb 24 | AACR abstracts accepted | Positive | +9.6% | Acceptance of two abstracts and posters for AACR 2026 on GLSI-100 and FLAMINGO-01. |
| Jan 27 | Cash burn update | Neutral | +9.6% | Disclosure of 2025 cash burn, year-end cash, and ATM funding strategy for FLAMINGO-01. |
Recent FLAMINGO-01 and AACR-related updates have often coincided with positive price reactions, with only one mild divergence on higher screening rates.
Over recent months, Greenwich LifeSciences has repeatedly highlighted progress in its Phase III FLAMINGO-01 program. On Jan 27, 2026 it detailed cash burn and ATM funding, followed by AACR abstract acceptance news on Feb 24, 2026. March updates covered increased screening rates on Mar 3, 2026, FDA approval of the first commercial GP2 lot on Mar 16, 2026, and a substantial recurrence-rate reduction on Mar 17, 2026. Today’s AACR meeting update continues this pattern of trial and data-milestone communication.
Market Pulse Summary
This announcement highlights upcoming AACR 2026 presentations featuring FLAMINGO-01 Phase III design and the first statistically significant immune-response data for GLSI-100. These data build on earlier disclosures about recurrence reduction, increased screening, and commercial GP2 supply. Investors may focus on immune-response robustness, subgroup results by HLA type, and safety as they relate to long-term efficacy. Monitoring future clinical readouts, funding updates, and regulatory filings will be important as the program advances.
Key Terms
immunotherapy medical
phase iii medical
gm-csf medical
intradermal injection medical
AI-generated analysis. Not financial advice.
STAFFORD, Texas, March 18, 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 the upcoming AACR Meeting 2026.
Two abstracts and two posters were accepted for presentation. The titles and authors of the abstracts are as follows:
Abstract Number: CT138 - Poster Section 52 on April 20, 2026, 2-5pm
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
- This will be the first abstract and poster from FLAMINGO-01 with statistically significant immune response data, potentially with subgroup analysis by the most prevalent HLA types. 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 and improved long term survival.
- Immune responses to GP2 were measured at baseline and over time using delayed-type-hypersensitivity (DTH) skin tests and other methods. The DTH skin test measures the diameter of the skin immune response to GP2 in millimeters, 48-72 hours after intradermal injection of a low concentration of GP2 without GM-CSF.
Abstract Number: CT227 - Poster Section 51 on April 21, 2026, 9am-12pm
Abstract Title: 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
Jaye Thompson1, Snehal Patel1, Mira Patel1, Anu Tammareddi1, F. Joseph Daugherty1, Mothaffar F. Rimawi2
1Greenwich LifeSciences, Stafford, TX,2Lester and Sue Smith Breast Center, Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX
- This abstract and poster will continue to update principal investigators at the conference about the study design of FLAMINGO-01.
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 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
FAQ
What will Greenwich LifeSciences present on April 20, 2026 at AACR (GLSI)?
What is abstract CT227 about at AACR April 21, 2026 for GLSI?
Does the AACR data show GLSI-100 prevents breast cancer recurrence (GLSI)?
When and where will the FLAMINGO-01 immune response poster (CT138) be shown at AACR 2026?
What measurements were used to assess immune response in FLAMINGO-01 (GLSI)?
