Greenwich LifeSciences (NASDAQ:GLSI) today presented a significant update on its clinical progress at the 2026 American Association for Cancer Research (AACR) Annual Meeting.
The company disclosed open-label immune response data from its ongoing FLAMINGO-01 Phase III clinical trial, which is evaluating the safety and efficacy of GLSI-100, an immunotherapy designed to prevent breast cancer recurrences.
The data presented on April 20, 2026, focused on a cohort of 247 patients who are HLA-A*02 negative.
These patients were administered GLSI-100, and their immune activation was measured via delayed-type hypersensitivity (DTH) skin reactions.
The results showed a robust increase in immune signaling, with the frequency of DTH reactions rising from an initial 5.2% to 20.4%.
This represents an approximate 290% increase in measurable immune response, a result that was highly statistically significant (McNemar p<0.001).
The FLAMINGO-01 trial continues to see strong recruitment and operational momentum.
To date, the company has screened over 1,300 patients as it works toward its enrollment targets.
Management noted that the trial remains in a blind-to-treatment phase for the randomized portions of the study, while these open-label findings provide early biological validation of the vaccine’s ability to prime the immune system.
While the immune response data is encouraging, Greenwich LifeSciences emphasized that the study remains ongoing.
Recurrence-event counts—the primary endpoint used to determine the vaccine's efficacy in preventing the return of cancer—remain very low across the study population.
Because the trial is event-driven, the final results may vary as data collection and cleaning continue.