Greenwich LifeSciences (GLSI) FDA Approvals

Greenwich LifeSciences' Drug in the FDA Approval Process

This section highlights FDA-related milestones and regulatory updates for drugs developed by Greenwich LifeSciences (GLSI). Over the past two years, Greenwich LifeSciences has reported clinical trial outcomes, regulatory submissions, approvals, and other FDA events for drugs and therapies such as GLSI-100. For definitions of regulatory abbreviations such as NDA, BLA, or PDUFA, see the event status legend.

GLSI-100 FDA Regulatory Timeline and Events

GLSI-100 is a drug developed by Greenwich LifeSciences for the following indication: Breast cancer recurrences. This drug is under review by the U.S. Food and Drug Administration (FDA). Below is a timeline of key regulatory milestones for this therapy.

Abstract - April 20,2026

• Drug: GLSI-100
• Announced Date: April 20, 2026
• Indication: Breast cancer recurrences

Greenwich LifeSciences to prevent breast cancer recurrences, today presents the published abstract and poster from the AACR Meeting 2026.,

Greenwich LifeSciences today published an abstract and poster at the AACR 2026 meeting, presenting initial immune and clinical signals from the Phase III FLAMINGO-01 study of GLSI-100 (GP2 + GM‑CSF) to prevent breast cancer recurrences. The joint abstract with the trial Steering Committee reports statistically significant delayed-type hypersensitivity (DTH) skin-test responses in the non‑HLA‑A*02 open‑label arm (n=247). DTH reactions rose from 5.2% at baseline to 20.4% at month 4 or 6 (≈290% increase; McNemar p<0.001). All common HLA‑A subgroups showed increased reactivity (100%–700% increases).

Preliminary recurrence data after the post‑immunization series (PIS) suggest a ~70–80% reduction in recurrences in the non‑HLA‑A*02 group, trending with Phase IIb and HLA‑A*02 results. The study is ongoing, data are being cleaned, and more immunologic assays and final results will follow. A second poster with the Phase III design—reporting over 1,300 patients screened to date—is also available on the company website.

Provided Update - April 7,2026

• Drug: GLSI-100
• Announced Date: April 7, 2026
• Indication: Breast cancer recurrences

Greenwich LifeSciences, Inc. today provided an update on new patent claims based on FLAMINGO-01 statistically significant open label immune response and recurrence rate data.

Greenwich LifeSciences, Inc. said it has filed new patent claims based on statistically significant open‑label data from the FLAMINGO‑01 study. The claims rely on immune response and recurrence rate results that the company says support its approach to treating certain breast cancers.

The company plans to expand analysis of GP2‑specific T cells by sequencing patients’ T‑cell DNA before and after treatment with GP2. By tracking T‑cell sequences over time, researchers hope to link specific T‑cell changes to measured immune responses and clinical outcomes, which could strengthen the new patent claims.

FLAMINGO‑01 and earlier GLSI‑100 Phase IIb data showed an 80% or greater reduction in metastatic breast cancer recurrence over five years, a peak immune response at six months, and a well‑tolerated safety profile. The PIS also produced strong immune signals in local skin tests and lab assays.Read Announcement

Provided Update - March 19,2026

• Drug: GLSI-100
• Announced Date: March 19, 2026
• Indication: Breast cancer recurrences

Greenwich LifeSciences, announced the initiation of new clinical sites in the US.

Greenwich LifeSciences said it is opening new clinical sites across the United States to expand a trial for patients with high‑risk, early‑stage HER2‑positive breast cancer. City of Hope locations will join the study, and Dr. Rita Rugo said she is pleased to help lead the effort on the trial’s steering committee. The move is intended to give more patients access to the study and speed enrollment.

The program includes the FLAMINGO‑01 and GLSI‑100 studies. Earlier clinical data for GLSI‑100 showed a strong immune response, a peak effect at about six months, a favorable safety profile, and an reported greater than 80% reduction in metastatic recurrence over five years in prior analyses. Greenwich LifeSciences says expanding U.S. sites will help test whether this immune‑focused approach can lower the risk of breast cancer coming back.

Provided Update - March 17,2026

• Drug: GLSI-100
• Announced Date: March 17, 2026
• Indication: Breast cancer recurrences

Greenwich LifeSciences, today provided a preliminary update showing a continued reduction in the recurrence rate in the fully enrolled, 250 patient, open label non-HLA-A*02 arm of FLAMINGO-01.

Greenwich LifeSciences reported a preliminary update showing a continued reduction in recurrence rate in the fully enrolled, 250‑patient, open‑label non‑HLA‑A*02 arm of FLAMINGO‑01. Because this arm lacks a direct placebo comparator, a Kaplan‑Meier survival analysis could not be performed; the company used an alternative comparative method described in the release to assess recurrence trends.

Results in the non‑HLA‑A*02 arm are trending similarly to prior Phase IIb results and to the HLA‑A*02 arms of FLAMINGO‑01. The Phase IIb study had shown large reductions in metastatic breast cancer recurrence (reported up to about 80% over five years). In the current arm, baseline immune activity, a rising immune response during the PIS, and the safety profile mirror those earlier findings. The PIS elicited a robust immune response on skin tests and immunological assays, and treatments were generally well tolerated.

Provided Update - March 16,2026

• Drug: GLSI-100
• Announced Date: March 16, 2026
• Indication: For breast cancer recurrences,

Greenwich LifeSciences, today provided the following update on the use of commercially manufactured GP2 in FLAMINGO-01.

Greenwich LifeSciences said all roughly 40 U.S. FLAMINGO-01 clinical sites have been supplied with commercially manufactured GP2 vials and began treating patients immediately. Distribution to the sites was completed within weeks, and sites transitioned to the commercial GP2 product without delay.

The company reported efficient distribution and close coordination with U.S. pharmacists and its warehouse partners. Greenwich also noted it internalized its clinical team in Q4 2025, which helped streamline communications and logistics. Greenwich said it will continue to support sites as the FLAMINGO-01 trial advances and work to ensure ongoing supply and patient dosing coordination.

Abstract Presentation - February 24,2026

• Drug: GLSI-100
• Announced Date: February 24, 2026
• Indication: Breast cancer recurrences

Greenwich LifeSciences, announced that two abstracts have been accepted for presentation at the upcoming American Association for Cancer Research (AACR) Annual Meeting 2026, including two corresponding posters.

Greenwich LifeSciences announced that two abstracts have been accepted for presentation at the American Association for Cancer Research (AACR) Annual Meeting 2026, and each acceptance will be accompanied by a corresponding poster. The AACR meeting runs April 17–22, 2026. The AACR will publish abstract titles on March 17, 2026 at 4:30 pm EST, the full abstracts on April 17, 2026 at 3:00 pm EST, and posters will be released on the day they are presented at the conference.

The accepted abstracts cover FLAMINGO‑01 open‑label Phase III data and the GLSI‑100 Phase IIb study. CEO Snehal Patel noted, "One of these abstracts will be the first abstract co‑authored by the Company and the full Steering Committee of FLAMINGO‑01." Attendees can expect posters detailing study design, immune response findings, and clinical outcomes.

Early GLSI‑100 results reported include a strong immune response with a peak at six months, a well‑tolerated safety profile, and an observed large reduction in metastatic breast cancer recurrence over five years of follow‑up. The presentations will provide more data.

Provided Update - January 22,2026

• Drug: GLSI-100
• Announced Date: January 22, 2026
• Indication: Breast cancer recurrences

Greenwich LifeSciences, Inc. today provided the update on the use of commercially manufactured GP2 in FLAMINGO-01.

Greenwich LifeSciences said the FDA has reviewed data and approved the first commercially manufactured lot of finished GP2 vials for use in the Phase III FLAMINGO-01 trial in the U.S. The company noted three active-ingredient lots made in 2023 could yield about 200,000 doses, and the first of three finished-vial lots was produced in 2024. Stability programs were started for all four lots, and that data was submitted to the FDA prior to approval of the first commercial vial lot.

CEO Snehal Patel said the approval and prior manufacturing investments help “de-risk” a U.S. BLA filing. Greenwich plans to begin using the new GP2 vials at all 40 U.S. sites in the coming weeks and cites three years of stability data to support a vial expiration date that could apply commercially.

The company said submitting manufacturing data for three lots is critical for a BLA and international filings. At least two more finished lots will be made so both clinical and manufacturing data are available, and the vials can be stored for launch or used in ongoing trials.

Provided Update - December 22,2025

• Drug: GLSI-100
• Announced Date: December 22, 2025
• Indication: Breast cancer recurrences

Greenwich LifeSciences, provided additional updates on FLAMINGO-01 and the Company's corporate strategy.

Greenwich LifeSciences updated its FLAMINGO-01 trial and corporate strategy after a recent investor conference. The company said its clinical plan is evolving to lower risk and speed approval by adding sites and countries, moving some trial operations in-house to cut costs, and capitalizing on growing patient-driven interest — about 140 sites are actively enrolling with plans to activate more in 2026 and discussions underway with sites in the UK and Canada.

The FLAMINGO-01 Data Safety Monitoring Board met twice in 2025 and recommended continuing the study. The Steering Committee endorsed planned changes such as increasing study size, accelerating enrollment, continuing enrollment past interim looks, and using interim analyses to resize or retime the study. Management highlighted the use of a commercial drug lot in ongoing operations.

Financially, the company is using an ATM program to cover a roughly $7M annual burn rate to limit near-term dilutive financings and preserve partnership opportunities. Greenwich is pursuing partnerships and additional patent filings to strengthen IP. The non-HLA-A*02 open-label arm (250 patients) is fully enrolled, showing a preliminary ~80% reduction in recurrences after initial immunization, but results are early and subject to further review.

Enrollment Update - December 8,2025

• Drug: GLSI-100
• Announced Date: December 8, 2025
• Indication: Breast cancer recurrences

Greenwich LifeSciences, announced the completion of enrollment in the open label non-HLA-A*02 arm of FLAMINGO-01.

Greenwich LifeSciences announced it has completed enrollment of 250 patients in the open-label non-HLA-A*02 arm of its Phase III FLAMINGO-01 trial testing GLSI-100 to prevent HER2+ breast cancer recurrence. Non-HLA-A*02 patients—those without the HLA-A*02 allele—make up about 55% of the trial population and were all treated with GLSI-100 in this arm.

The company paused enrollment earlier in the year and is now seeking regulatory approval to resume enrolling non-HLA-A*02 patients in a randomized design with a control arm. Greenwich says it has continued screening many such patients so it can restart quickly if approved. Preliminary analyses show immune response, safety, and recurrence trends in these 250 patients are similar to the HLA-A*02 arms and to prior Phase IIb results, which reported large reductions in recurrences.

Enrollment in the randomized HLA-A*02 arms continues. The most common non-HLA-A*02 types in FLAMINGO-01 include HLA-A*03, *24, *01, *11, *68, *29, *30, *23, and *33. Greenwich also highlighted potential patent and market implications if the non-HLA-A*02 approach is validated.

Provided Update - December 3,2025

• Drug: GLSI-100
• Announced Date: December 3, 2025
• Indication: Breast cancer recurrences

Greenwich LifeSciences, Provides Global Update on FLAMINGO-01, Screening Over 1,000 Patients to Date

Greenwich LifeSciences announced that its Phase III trial FLAMINGO-01 has screened over 1,000 patients to date. The study is running about 150 screenings per quarter (roughly 600 per year) across about 140 active sites — 40 in the U.S. and 100 in Europe. The company is weighing a plan to keep enrolling both HLA-A*02 and non-HLA-A*02 patients until interim analyses clarify the best size for each arm.

CEO Snehal Patel said the milestone shows strong interest from doctors and patients and that European site starts in 2025 have boosted momentum. Greenwich noted interest from other countries and said the high screening rate gives flexibility: it could support multiple interim looks, higher overall enrollment and event rates, and broader efficacy analysis across HLA types.

FLAMINGO-01 tests GLSI-100 in HER2-positive breast cancer patients after trastuzumab. The trial, led by Baylor College of Medicine, plans up to 150 global sites and includes separate arms for HLA-A*02 and other HLA types with planned interim analyses.

Expansion - October 9,2025

• Drug: GLSI-100
• Announced Date: October 9, 2025
• Indication: Breast cancer recurrences

Greenwich LifeSciences, Inc. announced the expansion of FLAMINGO-01 clinical trial to Austria.

Greenwich LifeSciences, Inc. announced that its Phase III clinical trial FLAMINGO-01, testing the immunotherapy GLSI-100 to prevent breast cancer recurrence, has officially expanded to Austria. European regulators approved the company’s application, making Austria the eleventh country in the study alongside Spain, France, Germany, Italy, Poland, Romania, Ireland, Portugal, Belgium, and the United States.

According to the European Cancer Information System, Austria recorded 6,070 new breast cancer cases in 2022, accounting for 28 percent of all female cancers. With 1,789 deaths that year, breast cancer remains the leading cause of cancer mortality among Austrian women.

CEO Snehal Patel said Greenwich LifeSciences is working closely with the Ordensklinikum Linz site in Upper Austria after patient interest prompted local investigators to join FLAMINGO-01. Staff training has begun, and the company hopes to activate Linz this year. Greenwich is also exploring additional trial locations in Vienna and Salzburg to broaden its geographic strategy in Austria.

Provided Update - September 18,2025

• Drug: GLSI-100
• Announced Date: September 18, 2025
• Indication: Breast cancer recurrences

Greenwich LifeSciences, In announced the expansion of FLAMINGO-01 clinical trial to Ireland.

Greenwich LifeSciences expanded its Phase III FLAMINGO-01 clinical trial to Ireland after European approval. This trial tests GLSI-100 immunotherapy to prevent breast cancer recurrences. Ireland joins Spain, France, Germany, Italy, Poland, Romania, and the United States as approved trial locations.

In 2022, 3,723 new breast cancer cases were diagnosed in Ireland, making it the most common cancer among women. Breast cancer caused 883 deaths, ranking second in cancer fatalities for Irish women.

Dr. Janice Walshe will serve as national principal investigator in Ireland. She leads Cancer Trials Ireland and will oversee the clinic at St. Vincent’s University Hospital in Dublin. Walshe has led breast cancer trials and presented research at international meetings.

CEO Snehal Patel said the team has trained staff at St. Vincent’s and presented FLAMINGO-01 there. Irish patients interested in the trial can enroll at the Dublin site.

Designation Grant - September 10,2025

Fast Track

• Drug: GLSI-100
• Announced Date: September 10, 2025
• Indication: Breast cancer recurrences

Greenwich LifeSciences, Inc announced that FDA has granted Fast Track designation for GLSI-100 in the HLA-A*02 patient population.

Greenwich LifeSciences, Inc., a clinical-stage biopharmaceutical company, announced that the FDA has granted Fast Track designation for GLSI-100 in patients with the HLA-A*02 genotype and HER2-positive breast cancer. This immunotherapy is being studied in the Phase III FLAMINGO-01 trial to help prevent cancer recurrence in patients who have completed standard HER2-targeted treatment.

Fast Track designation is designed to accelerate the development and review of therapies for serious conditions and unmet medical needs. With this status, the company can hold early and frequent meetings with the FDA, submit parts of its Biologic License Application (BLA) as they are completed, and potentially speed up regulatory decisions.

Dr. Jaye Thompson, VP of Clinical and Regulatory Affairs, said the FDA’s decision reflects the promise of GLSI-100 to improve outcomes. CEO Snehal Patel added that the company looks forward to ongoing discussions with regulators and preparing the BLA based on data from FLAMINGO-01.

Provided Update - August 13,2025

• Drug: GLSI-100
• Announced Date: August 13, 2025
• Indication: Breast cancer recurrences

Greenwich LifeSciences, Inc. announced the addition of clinical sites in Romania.

Greenwich LifeSciences, Inc. announced that European regulators approved expanding its Phase III FLAMINGO-01 trial into Romania. This addition joins roughly 150 approved sites across Spain, France, Germany, Italy, Poland and the U.S., bringing the total of actively enrolling global sites to about 123.

In 2022, Romania recorded 12,861 new breast cancer cases and 3,877 deaths, making it the most common and deadliest cancer among Romanian women. The company will partner with Dr. Nicoleta Antone, Head of the Breast Cancer Centre at the Chiricuta Institute of Oncology in Cluj Napoca, who will serve as national principal investigator alongside teams at three other Romanian sites.

CEO Snehal Patel said Romania is the first of several mid-sized European countries they plan to add to FLAMINGO-01. After multiple site visits and training sessions, the company expects to begin screening and enrolling Romanian patients in the coming months.

Provided Update - April 3,2025

• Drug: GLSI-100
• Announced Date: April 3, 2025
• Indication: Breast cancer recurrences

Greenwich Lifesciences Provides Update On Its Phase III Clinical Trial, Flamingo-01, Which Is Evaluating GLSI-100, An Immunotherapy To Prevent Breast Cancer Recurrences

Greenwich LifeSciences provided an update on its Phase III FLAMINGO-01 trial, which studies GLSI-100—an immunotherapy designed to prevent breast cancer recurrences. The trial is examining the treatment in patients with different human leukocyte antigen (HLA) types. So far, preliminary data regarding HLA prevalence, safety, and immune response are trending as expected in both the HLA-A*02 and non-HLA-A*02 arms.

The non-HLA-A*02 arm was expanded to include 250 patients in 2024 with approvals from US and EU regulators. Encouraging immune response data has raised the possibility of converting this arm into a second Phase III trial. This could create several pathways for the marketing approval of GLSI-100 and broaden its market potential. In the first quarter of 2025, the trial reached its highest screening rate of 150 patients per quarter at over 117 active global sites.

Provided Update - April 2,2025

• Drug: GLSI-100
• Announced Date: April 2, 2025
• Indication: Breast cancer recurrences

Greenwich LifeSciences announced the following update on FLAMINGO-01 open label immune response data.

Greenwich LifeSciences announced preliminary results from its Phase III FLAMINGO-01 trial, which evaluates GLSI-100 as an immunotherapy to prevent breast cancer recurrences. The open label immune response data showed that both HLA-A*02 patients and those with other HLA types experienced increasing immune responses over time. With more vaccinations, a growing number of patients exhibited injection site reactions or GP2 delayed-type hypersensitivity responses, indicating enhanced immune activation.

Interestingly, a baseline immune response to GP2 was observed before treatment, suggesting that GP2 may naturally trigger the immune system, possibly due to earlier treatments. These findings echo the earlier Phase IIb results and are encouraging for the safety and efficacy of GLSI-100. The company is also planning further analysis, including potential expansion of the trial to better understand T cell responses and to extend treatment eligibility.

Provided Update - March 17,2025

• Drug: GLSI-100
• Announced Date: March 17, 2025
• Indication: Breast cancer recurrences

Greenwich LifeSciences, announced the following update on FLAMINGO-01 open label safety data.

Greenwich LifeSciences recently shared an update on the FLAMINGO-01 open label safety data from its Phase III clinical trial of GLSI-100. The company noted that a preliminary review of safety data in all study arms shows that the GP2 immunotherapy continues to be well-tolerated. No new safety signals for GLSI-100 have been identified, and the most common side effect remains injection site reactions, which are viewed as a sign of an immune response. The Data Safety Monitoring Board (DSMB) has met, reviewed the data, and recommended that the study continue without any modifications. These early findings build confidence in the ongoing trial, as the safety profile of GLSI-100 appears consistent with previous observations. Greenwich LifeSciences plans to further analyze immune response data and potentially share more detailed results at future scientific meetings.

Provided Update - February 10,2025

• Drug: GLSI-100
• Announced Date: February 10, 2025
• Indication: Breast cancer recurrences

Greenwich LifeSciences, announced the update on FLAMINGO-01 open label HLA data.

Greenwich LifeSciences announced an update on the FLAMINGO-01 open label HLA data. The analysis, conducted while maintaining the study blind, revealed that about 46% of all screened patients have at least one HLA-A*02 allele. This finding meets expectations and supports the trial’s sample size estimates, which anticipated a prevalence of 40–50%.

The open label arm is designed to evaluate the safety and efficacy of the GLSI-100 vaccine in patients who do not carry the HLA-A*02 allele. Researchers believe this group may provide valuable information, as it could be large enough to draw conclusions on immune response and clinical outcomes. In addition, the study plans to investigate how different HLA combinations, including patients with two copies of HLA-A*02, influence the vaccine’s effectiveness.

Provided Update - January 22,2025

• Drug: GLSI-100
• Announced Date: January 22, 2025
• Indication: Breast cancer recurrences

Greenwich LifeSciences, today provided the following update on the commercial manufacturing of GP2.

Greenwich LifeSciences provided an update on the commercial manufacturing of GP2. The company manufactured the first three commercial lots of GP2 in 2023 at an approved facility, producing enough active ingredient for approximately 200,000 doses. Stability programs for the drug have started, and data from these lots has been submitted to both the FDA and the European Medicines Agency. In 2024, the first commercial lot was filled into vials for either commercial sale or clinical use, with final testing nearly complete. The company is progressing toward filing a Biological License Application (BLA) in the United States by ensuring both clinical and manufacturing data are ready for review. CEO Snehal Patel highlighted plans to manufacture additional lots, finalize packaging and trade names, and work closely with regulators in the US and Europe to meet all requirements before a potential market launch.

Provided Update - January 13,2025

• Drug: GLSI-100
• Announced Date: January 13, 2025
• Indication: Breast cancer recurrences

Greenwich LifeSciences, announced the activation of clinical sites in France.

Greenwich LifeSciences announced the activation of clinical sites in France for its Phase III FLAMINGO-01 trial. The study is designed to evaluate GLSI-100, an immunotherapy aimed at preventing breast cancer recurrences. The trial will now be conducted at approximately 19 sites within the Unicancer breast cancer group, a leading academic network dedicated to fighting cancer in France.

These sites, part of a network of top French cancer centers, were approved by French authorities in early 2024. Initial site initiation visits and trainings were carried out at 15 locations during the latter half of 2024, with the remaining four sites set to start up in early 2025. This expansion is expected to bring innovative treatments to a wide population, as France records a high number of breast cancer cases and related deaths each year.