FLAMINGO-01 Hits Milestone: FDA Clears Commercial GP2 As GLSI Stock Climbs to 52-Week High

Greenwich LifeSciences reported a significant regulatory achievement as the FDA approved its first commercially manufactured batch of GP2 for use in the ongoing FLAMINGO-01 Phase 3 trial. This development marks a crucial step forward for GLSI-100, an immunotherapy candidate designed to prevent breast cancer recurrences in patients at high risk. The market responded enthusiastically, with GLSI stock trading up 48% to $33 in pre-market activity, reaching a new 52-week high. The announcement underscores the company’s progress toward a potential Biologics License Application and accelerates its path to commercialization.

FDA Greenlights First Commercial GP2 Batch for FLAMINGO-01

The regulatory clearance covers commercial-grade GP2 vials produced by Greenwich LifeSciences, which will now begin distribution to all 40 U.S. clinical sites participating in FLAMINGO-01. The company had previously manufactured three commercial lots of the GP2 active ingredient in 2023 and completed its first batch of filled vials in 2024. Stability testing for all lots remains underway, with three years of data already compiled.

According to the disclosure, the newly authorized vials will ship to trial sites in the coming weeks and are positioned to support both the ongoing Phase 3 investigation and preparations for future market entry. The commercial-grade material represents a major step in demonstrating manufacturing consistency and quality at scale—essential requirements for eventual regulatory approval and market availability.

Scaling Production: Multiple GP2 Lots Ready for Regulatory Submissions

Greenwich LifeSciences emphasized that its BLA submission strategy hinges on manufacturing data from multiple production batches. The company disclosed it has received Fast Track designation from the FDA, expediting the review timeline. Additional GP2 product batches are scheduled for production to generate sufficient clinical and manufacturing datasets for comprehensive regulatory evaluation.

Beyond the U.S., the company plans to submit its manufacturing documentation package to regulatory authorities in Europe, the United Kingdom, and Canada. This multi-jurisdictional approach aligns with FLAMINGO-01’s global expansion strategy, which targets up to 150 clinical trial sites worldwide and strengthens the pathway for potential international commercialization.

FLAMINGO-01 Open-Label Results Point to Significant Recurrence Risk Reduction

Preliminary data from FLAMINGO-01 demonstrate encouraging clinical signals. More than 1,000 patients have undergone screening for the trial, and the 250-patient non-HLA-A*02 open-label arm has achieved full enrollment. Early findings from this cohort indicate approximately an 80% reduction in breast cancer recurrence following completion of the Primary Immunization Series, a result consistent with trends observed in the company’s preceding Phase 2b study.

Researchers caution that these preliminary results remain subject to modification as the study continues and blinded treatment arms mature. However, the early signals suggest GLSI-100’s potential to reduce invasive breast cancer recurrence risk in patients who have already received standard HER2-targeted therapy with trastuzumab.

Trial Design and Market Context

FLAMINGO-01 evaluates GLSI-100 in HER2-positive breast cancer patients who persist in high recurrence risk despite completing standard neoadjuvant and adjuvant trastuzumab treatment. GP2, a peptide derived from the HER2 protein prevalent in most breast cancers, serves as the immunotherapy’s active component. The therapy combines GP2 with GM-CSF to enhance immune response against cancer cells.

The Phase 3 trial incorporates both blinded and open-label arms and is statistically powered to detect a hazard ratio of 0.3 for invasive breast cancer-free survival. Over the past year, GLSI stock has ranged between $7.78 and $32.91, reflecting investor interest in the company’s clinical pipeline and regulatory progress. The recent rally to $33 signals market confidence in FLAMINGO-01’s advancement toward potential approval.