Greenwich LifeSciences Inc. disclosed that its Phase III FLAMINGO‑01 trial has shown an approximately 80% reduction in breast‑cancer recurrence among the 250 patients in the open‑label non‑HLA‑A*02 arm. The reduction was derived from two independent statistical methods that compensate for the lack of a placebo comparator in this cohort, and the result aligns closely with the 80% reduction observed in the earlier Phase IIb study.
The 80% decline in recurrence is a pivotal efficacy signal that could accelerate the FDA’s review of GLSI‑100 under its Fast Track designation. A Fast Track designation shortens the regulatory timeline and provides the company with more frequent interactions with the FDA, potentially bringing the therapy to market sooner. The data also reinforce the company’s claim that GLSI‑100 is a first‑in‑class therapeutic vaccine for preventing breast‑cancer recurrence in the post‑treatment setting.
While the preliminary analysis did not publish a specific hazard ratio, the Phase IIb trial reported a hazard ratio near 0.2. The absence of a confirmed hazard ratio for the Phase III data means the company is focusing on the recurrence‑rate reduction as the primary metric of efficacy.
CEO Snehal Patel highlighted the milestone, noting that the first non‑HLA‑A02 patient completed the full primary and booster vaccination series over three years. He added that immune‑response and safety data in this arm are trending similarly to the HLA‑A02 cohorts, underscoring the consistency of GLSI‑100’s safety profile.
Following the announcement, the market reacted strongly, with the company’s shares surging 37%. Investors view the result as a validation of GLSI‑100’s first‑in‑class potential and a significant expansion of the $8–10 billion HER2‑positive breast‑cancer vaccine market. The company remains a clinical‑stage biopharma with no current revenue, but it maintains robust liquidity and no debt, and insider buying signals management confidence in the therapy’s future.
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