GLSI News & Events

Greenwich LifeSciences focused on its Phase III clinical trial, FLAMINGO-01 presents the published abstract and poster from the AACR Meeting 2026. This is the first abstract and poster presented jointly with the Steering Committee of FLAMINGO-01 with statistically significant delayed-type-hypersensitivity immune response data, with subgroup analysis by the most prevalent HLA types. In the non-HLA-A*02 open label arm where all patients were treated with GLSI-100, immune responses to GP2 were measured at baseline and over time using skin tests and other methods. The other methods will be presented at a future conference. A DTH reaction (redness and/or induration) was used to assess in vivo immune responses in patients. The DTH orthogonal mean was also measured 48-72 hours after injection but is not reported here. In this preliminary data analysis, there was a significant increase in percentage of patients experiencing a DTH reaction in month 4 or month 6 compared to baseline. There were 191 patients with both baseline and month 4 or 6 assessments. The frequency of DTH reactions increased by approximately 4x in the total open-label non-HLA-A*02 population, increasing from 5.2% of the patients experiencing a DTH reaction at baseline, prior to any GLSI-100 administration, to 20.4% of the patients experiencing a DTH reaction in month 4 or month 6. As reported in Table 1 of the poster, each HLA-A type exhibited more frequent immune reactivity after treatment with GLSI-100 than at baseline with frequency increasing from 100% to 700%. Baseline DTH reaction prior to any treatment suggests that GP2 may be a natural antigen and that GP2 specific T cells may exist in some patients prior to any treatment with GLSI-100. Baseline immune response to GP2 prior to any vaccination with GP2 was also observed in the Phase IIb trial and is being observed in the blinded randomized arms of FLAMINGO-01, where HLA-A*02 only patients are being vaccinated. This statistically significant non-HLA-A02 open label arm immune response data is trending similarly to the immune response data in the HLA-A02 patients in the Phase IIb study and the HLA-A*02 arms of FLAMINGO-01. The study is ongoing and data collection and cleaning continue, while some patients may still be in their PIS vaccination phase, so final results may vary. The immune response abstract and poster conclusion: The statistically significant increase in the incidence of DTH reactions over time found in this preliminary analysis of GLSI-100 treated non-HLA-A02 patients shows that GLSI-100 treatment should not be limited to HLA-A02 patients. Patients treated with GLSI-100 were increasingly able to mount an immune response to GP2 as evidenced in this preliminary data. Future investigations may explore the use of immune responses to assess correlation of DTH to ISRs, immunogenicity of GLSI-100 by specific HLA type, timing of boosters to sustain immunity, clinical site performance, and the discontinuation of treatment for non-responders. In addition, the second poster describing the Phase III trial design, which is being presented on Tuesday, April 21, can be downloaded and seen on the website using the same link. This poster provides an update that over 1,300 patients have been screened to date in FLAMINGO-01. The new protocol amendment, which is still under regulatory review in certain countries, is not discussed.

Greenwich LifeSciences announced the initiation of new clinical sites in the US. The Phase III clinical trial has recently been activated at City of Hope, one of the largest and most advanced cancer research and treatment organizations in the United States - specifically at its network sites in Los Angeles and Orange counties, Arizona, Atlanta, and Illinois. Principal investigator at City of Hope, Hope S. Rugo, M.D., continues her participation on the Steering Committee. Her prior site at University of California San Francisco, where she is Professor Emeritus, is still participating in the study.