BriaCell Announces Dynamic CAML PD-L1 Changes Predict Survival in Metastatic Breast Cancer

PHILADELPHIA and VANCOUVER, British Columbia, Oct. 23, 2026 /CourierPR/ -- BriaCell Therapeutics Corp., a clinical-stage biotechnology company, has announced findings from a prospective pooled analysis of 111 heavily pretreated metastatic breast cancer (MBC) patients at the European Society for Medical Oncology (ESMO) Congress 2026, taking place October 23-27, 2026, in Madrid, Spain. The analysis, presented in Poster #4506, focuses on the dynamic changes in PD-L1 expression on circulating cancer-associated macrophage-like cells (CAMLs) and their association with progression-free survival (PFS) and overall survival (OS) following immunotherapy.

The analysis included patients from multiple studies, including BriaCell’s earlier Phase 1/2 Bria-IMT™ study. Patients had a median age of 59 years, with a range of 32 to 77 years, and had received a median of two prior metastatic lines of therapy, with a range of one to 13. Among the 111 patients, 39% were estrogen receptor-positive, 31% were progesterone receptor-positive, 5% were HER2-positive, and 60% had triple-negative breast cancer.

The study evaluated changes in PD-L1 expression on CAMLs before and after initiation of immunotherapy. Key findings included: - At baseline, CAML PD-L1 was not significantly associated with either PFS or OS. - At T1, approximately 37 days following initiation of immunotherapy, CAML PD-L1 was significantly associated with PFS (HR=1.86; p=0.0276), but not OS (HR=1.28; p=0.5663). - At T2, approximately three months following initiation of immunotherapy, CAML PD-L1 was significantly associated with both PFS (HR=2.73; p=0.0028) and OS (HR=2.27; p=0.0420).

These results suggest that monitoring dynamic PD-L1 changes in circulating tumor-associated immune cells following initiation of immunotherapy may provide information regarding clinical benefit in patients with MBC and are consistent with findings reported in the Bria-IMT Phase 2 study.

The analysis also indicates that a pretreatment tumor PD-L1 combined positive score (CPS) of 10 or greater was not significantly associated with improved PFS or OS in the pooled population. These findings are consistent with the results of BriaCell’s Phase 2 survival data in a similar MBC patient population treated with the same Bria-IMT combination regimen.

BriaCell’s pivotal Phase 3 clinical study of Bria-IMT plus an immune checkpoint inhibitor (CPI) in metastatic breast cancer is ongoing. The study’s primary endpoint is overall survival, comparing patients treated with the Bria-IMT combination regimen with patients receiving physician’s choice treatment. The planned interim analysis will be conducted following 144 patient deaths. Positive results from the pivotal Phase 3 study could support a potential application for marketing approval of Bria-IMT in metastatic breast cancer.

For additional information on BriaCell’s pivotal Phase 3 study of Bria-IMT and an immune checkpoint inhibitor in metastatic breast cancer, please visit ClinicalTrials.gov NCT06072612.