On January 22, 2026 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, reported the following update on the use of commercially manufactured GP2 in FLAMINGO-01.
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FDA Reviews and Approves Use of 1st GP2 Commercial Lot in FLAMINGO-01
The first three commercial lots of GP2 active ingredient were manufactured in 2023 in an approved commercial facility, which could be used to prepare approximately 200,000 doses of GP2. In 2024, the first of three commercial lots filling GP2 into vials for commercial sale or for clinical use was manufactured in a commercial facility. In addition, drug stability programs were initiated for all four lots. Data on these commercial lots was recently submitted to the FDA, and after review, the first commercial lot of GP2 vials is now approved for use in FLAMINGO-01 in the US.
CEO Snehal Patel commented, "With our manufacturing investments in 2023 and 2024, and now the FDA’s review and approval to use the first commercial lot of finished GP2 vials in FLAMINGO-01, we have taken major steps to further de-risk the filing of a BLA in the US. We plan to start using these new GP2 vials in the coming weeks at all 40 US sites. We have 3 years of stability data to support the GP2 vial expiration date which may translate to the commercial expiration date of GP2 vials."
Preparation for Filing of BLA in the US under Fast Track Designation
In addition to the submission of the Phase III clinical data, submitting commercial manufacturing data for three lots will be critical to the filing of a Biological License Application (BLA) for GLSI-100 in the US and for regulatory filings in other countries. These GP2 vials can be stored in preparation for commercial launch or used in clinical trials. At least two more lots of finished GP2 product will be manufactured so that both clinical and manufacturing data are available for review by the biologics division of the FDA prior to potentially being granted a marketing license with up to 12 years of market exclusivity based on current law.
Mr. Patel further added, "We look forward to submitting the same manufacturing data to regulatory agencies in Europe, the United Kingdom, and Canada. The objective is to manufacture GP2 and to conduct FLAMINGO-01 at the 150 leading clinical sites in the US and Europe in a manner that provides for an efficient transition to product launch and commercial sales if GLSI-100 is approved."
About FLAMINGO-01 Open Label Phase III Data
More than 1,000 patients have been screened with a current screen rate of approximately 600 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 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: [email protected]
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.
(Press release, Greenwich LifeSciences, JAN 22, 2026, View Source [SID1234662166])