Shares of Greenwich LifeSciences (NASDAQ:GLSI) soared about 37% after the clinical-stage biotech released early data from its FLAMINGO-01 study indicating a sharp drop in breast cancer recurrence rates.
The company said preliminary analysis from the open-label, non-HLA-A02 arm of the trial — which includes 250 patients — showed an estimated reduction in recurrence of roughly 80%. This part of the study is evaluating GLSI-100, an immunotherapy aimed at preventing the return of breast cancer.
Because the non-HLA-A02 arm does not include a direct placebo control, Greenwich LifeSciences applied two separate analytical approaches to estimate the effect. One compared observed recurrence rates with historical outcomes from the Katherine study, while the other assessed recurrence during the early vaccination phase versus the period after peak immune response was reached.
“We are very excited to see a positive trend in the recurrence rate in the non-HLA-A02 arm of FLAMINGO-01, as assessed multiple ways, that is trending similarly to the Phase IIb trial results where HLA-A02 patients were treated,” said CEO Snehal Patel in the announcement.
The company noted that the findings are consistent with results from its earlier Phase IIb trial, which showed up to an 80% reduction in breast cancer recurrence compared with placebo. That study involved 46 patients treated with GLSI-100 and 50 patients who received placebo.
Greenwich LifeSciences also disclosed that the first participant has now completed the full vaccination regimen, consisting of 11 primary and booster doses administered over a three-year period. While stressing that the current data remain preliminary, the company said the encouraging trend supports the continued enrollment and treatment of non-HLA-A02 patients within a placebo-controlled framework.