Greenwich LifeSciences, Inc. (NASDAQ: GLSI) provided an update on its Phase 3 FLAMINGO-01 clinical trial evaluating GLSI-100, an immunotherapy designed to prevent breast cancer recurrence, announcing that the Data Safety Monitoring Board (DSMB) recommended the trial continue without modification following its May 2026 review. The company also said regulatory authorities in the U.S. and Europe have supported planned protocol changes, including expanding enrollment to as many as 2,000 patients, increasing enrollment rates by including all HLA types, and maintaining enrollment through interim analyses to strengthen the study design and increase the probability of success.
According to the company, more than 1,500 patients have been screened across approximately 170 to 180 clinical sites in 11 countries, with plans to expand into additional European markets as well as the U.K. and Canada. This broad geographic reach underscores the global effort to evaluate GLSI-100, a 9-amino acid transmembrane peptide of the HER2 protein, which is expressed in 75% of breast cancers at low, intermediate, or high levels. The immunotherapy aims to prevent recurrences in patients who have previously undergone surgery.
The company also reported preliminary data from the fully enrolled open-label non-HLA-A*02 arm, which continues to show a 70% to 80% reduction in breast cancer recurrence following the primary immunization series. However, Greenwich LifeSciences emphasized that these findings remain preliminary and are not predictive of the final Phase 3 results. The DSMB’s recommendation to continue without modification provides a measure of confidence in the trial’s safety profile, while the expanded study design could enhance the statistical power needed to confirm efficacy.
The implications of this announcement are significant for breast cancer patients and the biopharmaceutical industry. If GLSI-100 proves successful, it could offer a new treatment option for preventing recurrence in a large patient population, particularly those with HER2-expressing tumors. The expanded enrollment, including all HLA types, may also broaden the potential patient population that could benefit from the therapy. For investors, the positive DSMB review and regulatory support for protocol changes reduce some uncertainty around the trial’s execution, though final results remain pending. The full press release is available at https://ibn.fm/elLnNA.
Greenwich LifeSciences is a clinical-stage biopharmaceutical company focused on developing GP2, an immunotherapy to prevent breast cancer recurrences. The company’s Phase III trial, FLAMINGO-01, is a key milestone in advancing this potential therapy. More information is available on the company’s website at www.greenwichlifesciences.com.
