Key insights
- Greenwich LifeSciences presented positive Phase III trial data for its breast cancer immunotherapy GLSI-100, showing increased immune response in patients. The FDA reviewed protocol changes, potentially accelerating enrollment. While positive for GLSI, the news has a limited broader impact on US equities, primarily affecting the biotech sector.
Greenwich LifeSciences Inc. (GLSI) presented data from its Phase III FLAMINGO-01 clinical trial at the AACR Meeting 2026, showing immune response results for its breast cancer immunotherapy GLSI-100.
The company reported data from 247 patients in the non-HLA-A*02 open label arm of the trial, where all patients received GLSI-100 treatment. The study measured delayed-type-hypersensitivity (DTH) immune responses using skin tests at baseline and over time.
Results showed the frequency of DTH reactions increased approximately four times, from 5.2% of patients experiencing a reaction at baseline to 20.4% at month 4 or 6 (p < 0.001). The analysis included 191 patients with both baseline and follow-up assessments.
The FLAMINGO-01 trial is evaluating GLSI-100, which combines GP2 peptide with GM-CSF, in HER2-positive breast cancer patients who had residual disease or high-risk pathologic complete response after neoadjuvant and adjuvant therapy. The treatment has Fast Track designation from the FDA.
The study includes approximately 140 sites in the US and Europe. The randomized arms plan to enroll about 500 HLA-A02 patients, while the non-HLA-A02 arm has enrolled 250 patients. The company reported screening over 1,300 patients to date.
CEO Snehal Patel stated the immune response data supports combining HLA-A02 and non-HLA-A02 patients in the same randomized arms. The FDA recently reviewed protocol changes allowing previously screened non-HLA-A*02 patients to be enrolled.
The trial is designed to detect a hazard ratio of 0.3 in invasive breast cancer-free survival, requiring 28 events for analysis. An interim analysis will be conducted when 14 events occur.