Greenwich LifeSciences (Nasdaq: GLSI) presented FLAMINGO-01 Phase III open-label immune response data at AACR 2026 on April 20, 2026. In 247 non-HLA-A*02 patients vaccinated with GLSI-100, delayed-type-hypersensitivity (DTH) reactions rose from 5.2% to 20.4% (≈+290%, McNemar p < 0.001).
Study remains ongoing, with over 1,300 patients screened and data collection/cleaning continuing; recurrence-event counts remain very low, so final results may vary.
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Positive
DTH reactions +290% (5.2% to 20.4%) in non-HLA-A*02 open-label arm
Statistically significant immune response (McNemar p < 0.001)
Full enrollment of non-randomized arm: n=247 patients vaccinated with GLSI-100
Screening momentum: over 1,300 patients screened for FLAMINGO-01
Regulatory options: ability to pursue combined HLA-A*02 and non-HLA analyses to increase power
Negative
Results are preliminary and interim; data collection and cleaning are ongoing
Very low recurrence rate (~1% per year) limits correlation of immune response to clinical outcomes
Protocol amendment remains under regulatory review in certain countries, potentially delaying implementation
+2.70%
Since News
$28.49
Last Price
$27.26
$30.26
Day Range
+$10M
Valuation Impact
$384.32M
Market Cap
0.0x
Rel. Volume
Following this news, GLSI has gained 2.70%, reflecting a moderate positive market reaction.
The stock is currently trading at $28.49.
This price movement has added approximately $10M to the company’s valuation.
Data tracked by StockTitan Argus (15 min delayed). Upgrade to Silver for real-time data.
Open-label arm size
247 patients
Non-HLA-A*02 open-label arm of FLAMINGO-01
Immune-response dataset
191 patients
Patients with baseline and month 4 or 6 DTH assessments
Baseline DTH rate
5.2%
Patients with DTH reaction before any GLSI-100 dosing
Post-treatment DTH rate
20.4%
Patients with DTH reaction at month 4 or 6
Increase in DTH frequency
≈4x (290%)
Change from baseline to month 4/6 in non-HLA-A*02 arm
Recurrence reduction
≈70–80%
Preliminary reduction after Primary Immunization Series in open-label arm
Recurrence rate
≈1% per year
Observed rate too low to correlate individual biomarkers
Patients screened
over 1,300
Cumulative screening in FLAMINGO-01 Phase III trial
$27.74
Last Close
Volume
Volume 229,369 is above the 20-day average of 132,732 (relative volume 1.73).
high
Technical
Shares at $27.74 are trading above the 200-day MA of $16.39 and about 18.65% below the 52-week high of $34.10.
GLSI gained 2.36% on elevated volume while momentum-screened biotech peers were mixed, with 2 up and 1 down and no same-day peer news, pointing to stock-specific reaction to the FLAMINGO‑01 data.
Date
Event
Sentiment
Move
Catalyst
Oct 09
Trial expansion Austria
Positive
-2.3%
Regulatory approval to add Austria sites to Phase III FLAMINGO‑01.
Oct 02
Trial expansion Belgium
Positive
+5.3%
Expansion of FLAMINGO‑01 into Belgium as tenth approved country.
Sep 30
Trial expansion Portugal
Positive
-2.1%
Regulatory approval to add Portugal sites to Phase III trial.
Sep 18
Trial expansion Ireland
Positive
+3.5%
Ireland added as new country in FLAMINGO‑01 Phase III program.
Sep 10
Fast Track designation
Positive
+3.5%
FDA granted Fast Track designation for GLSI‑100 in breast cancer.
Pattern Detected
Clinical-trial announcements have produced mixed but generally modest moves, with both positive and negative reactions to expansion updates and regulatory milestones.
Recent Company History
Over the past year, GLSI’s key milestones have centered on advancing Phase III FLAMINGO‑01 and GLSI‑100. The company secured Fast Track designation and steadily expanded trial geography across Ireland, Portugal, Belgium, and Austria, highlighting a broad European footprint. Price reactions to these clinical updates have been mixed, with both gains and pullbacks. Today’s AACR immune‑response readout fits into this pattern of incremental clinical de‑risking as the global Phase III program continues to mature and broaden enrollment.
+1.6%
Average Historical Move
clinical trial
Past clinical‑trial headlines moved GLSI by an average of ±1.6%. Today’s 2.36% move on AACR immune‑response data sits slightly above that typical reaction range.
Clinical updates progressed from Fast Track designation to multi‑country Phase III expansion, now adding immune‑response and enrollment depth data from FLAMINGO‑01.
This announcement highlights statistically significant immune‑response data from the non‑HLA‑A*02 open‑label arm of FLAMINGO‑01, with DTH rates rising from 5.2% to 20.4% and preliminary recurrence reductions of 70–80%. Over 1,300 patients have been screened, underscoring growing Phase III scale. The data remain preliminary and subject to cleaning, and recurrence events are still sparse. Key metrics to watch include future randomized-arm readouts, durability of response, and regulatory feedback as protocol amendments progress.
delayed-type-hypersensitivity
medical
“This is the first abstract and poster presented … with statistically significant delayed-type-hypersensitivity (DTH) immune response data”
An immune reaction that appears hours to days after exposure to a substance and is driven by specialized white blood cells rather than antibodies; think of it as a slow-acting neighborhood watch that mobilizes when it recognizes a repeat intruder. Investors care because delayed-type hypersensitivity is used as a measure of cell-based immune response, can be an efficacy or safety signal in vaccine and immunotherapy trials, and therefore can affect clinical outcomes, regulatory decisions and a company’s valuation.
hla-a*02
medical
“In the non-HLA-A*02 open label arm where all patients (n=247) were treated with GLSI-100”
HLA-A*02 is a common genetic variant of the HLA-A gene, which helps the immune system recognize infected or abnormal cells. Think of it as a particular model of a lock on cells that determines which immune system “keys” can fit; this matters to investors because many immunotherapies, vaccines and diagnostic tests are designed for or tested in people with this variant, affecting who is eligible for a treatment and the potential market size.
gm-csf
medical
“GP2 is a biologic nine amino acid peptide … in combination with Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF)”
GM‑CSF is a naturally occurring immune signaling protein that tells certain white blood cells to grow, move and fight infection — like a traffic cop directing immune cells to where they’re needed. Investors care because drugs that boost or block GM‑CSF can treat cancers, inflammatory conditions or infectious diseases, so clinical trial results, approvals, dosing and safety concerns can materially affect a biotech or pharmaceutical company’s clinical and commercial prospects.
intradermal
medical
“6 intradermal injections of GLSI-100 will be administered over the first 6 months”
Intradermal means delivering a drug or vaccine into the middle layer of the skin rather than into muscle or under the skin. Investors care because this delivery route can change how much of a product is needed, how fast it works, and what safety or regulatory testing is required—similar to placing a small patch inside the layers of a cake to get a different effect than spreading it on top.
injection site reactions
medical
“Immune responses to GP2 were measured over time using delayed-type-hypersensitivity (DTH) skin tests and injection site reactions (ISRs).”
Injection site reactions are local skin and tissue responses—such as redness, swelling, pain, itching or bruising—that occur where a drug or vaccine is injected. For investors, they matter because frequent or severe reactions can affect patient acceptance, regulatory review, labeling, and overall commercial success in the same way a product with bothersome side effects can struggle to gain long-term customers.
pcr
medical
“breast cancer patients with residual disease or high-risk PCR after both neo-adjuvant and postoperative adjuvant anti-HER2 therapy”
PCR (polymerase chain reaction) is a laboratory method that makes many copies of a tiny piece of genetic material (DNA or RNA) so scientists can detect and study it reliably — think of photocopying a faint, tiny note until the words are easy to read. For investors, PCR matters because it underpins diagnostic tests, drug development, and biotech tools whose sales, regulatory approvals, and real-world use can materially affect company revenues and market perceptions during health events or product launches.
AI-generated analysis. Not financial advice.
04/20/2026 – 06:00 AM
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: 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 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: 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 (GLSI) report about GLSI-100 immune responses on April 20, 2026?
They reported a significant rise in DTH responses: 5.2% to 20.4% (≈+290%) in 247 non-HLA-A*02 patients. According to the company, the change was statistically significant (McNemar p < 0.001) and supports broader evaluation beyond HLA-A*02.
How many patients were in the FLAMINGO-01 non-HLA-A*02 arm presented at AACR 2026?
The open-label non-HLA-A*02 arm included 247 vaccinated patients. According to the company, all 247 received GLSI-100 and immune responses were assessed at baseline and at month 4 or month 6.
Does the GLSI-100 data from FLAMINGO-01 show clinical recurrence reduction for GLSI stock (GLSI)?
Not yet — immune response data are preliminary and recurrence events are very few (~1%/year). According to the company, low event rates prevent validating DTH as an individual biomarker for recurrence at this time.
What statistical significance did Greenwich LifeSciences report for the DTH increase in FLAMINGO-01 (GLSI)?
The company reported the DTH increase was statistically significant with McNemar p < 0.001. According to the company, this supports that GLSI-100 elicits measurable immune responses in non-HLA-A*02 patients.
How many patients have been screened overall for FLAMINGO-01 as of April 20, 2026?
Over 1,300 patients have been screened to date. According to the company, screening remains active and many previously screened non-HLA-A*02 patients are being enrolled following protocol changes.