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- Dynamic changes in PD-L1 expression on circulating cancer-associated macrophage-like cells (CAML) were significantly associated with progression-free survival and overall survival following immunotherapies including the BriaCell regimen
- Findings from a prospective pooled analysis of 111 heavily pretreated metastatic breast cancer patients support further evaluation of circulating CAML PD-L1 as a potential biomarker of clinical benefit from immunotherapies
- Pooled analysis includes patients from multiple studies, including BriaCell's earlier Phase 1/2 Bria-IMTâ„¢ study
briacell therapeutics corp. (Nasdaq: BCTX, BCTXL) (TSX: BCT) ("BriaCell" or the "Company"), a clinical-stage biotechnology company developing novel immunotherapies to transform cancer care, today announced the presentation of clinical biomarker findings from a prospective pooled analysis of patients with metastatic breast cancer ("MBC") treated with immune based therapies including the BriaCell regimen at the European Society for Medical Oncology ("ESMO") Congress 2026, taking place October 23-27, 2026 in Madrid, Spain. The data shown is pooled from several studies including BriaCell's Phase 12 Bria-IMT study.
The analysis evaluated changes in programmed death-ligand 1 ("PD-L1") expression on circulating cancer-associated macrophage-like cells ("CAMLs") before and after initiation of immunotherapy and their association with progression-free survival ("PFS") and overall survival ("OS"). The findings suggest that changes in CAML PD-L1 following treatment may provide information regarding clinical outcomes that are not captured by a single pretreatment measurement.
"We are encouraged by these findings showing that dynamic changes in a circulating immune biomarker were associated with progression-free and overall survival in patients with metastatic breast cancer treated with immunotherapies," stated Dr. William V. Williams, BriaCell's President and CEO. "These results support further study of CAML PD-L1 as a potential tool for understanding treatment response and identifying patients most likely to benefit from immunotherapy, including the Bria-IMT regimen."
Poster #4506 - Monitoring Circulating Cancer Associated Macrophage-like Cell PD-L1 Predicts Clinical Outcomes in Metastatic Breast Cancer Treated with Immune Checkpoint Inhibitors
The prospective, multi-institutional pooled analysis included 111 patients with MBC who had received at least one prior line of therapy and were treated with pembrolizumab, retifanlimab, atezolizumab, or nivolumab. Some also received combination therapy with the Bria-IMT regimen. 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.
Peripheral blood samples were collected prior to initiation of immunotherapy, approximately 37 days after initiation of immunotherapy ("T1"), and approximately three months after initiation of immunotherapy ("T2"). CAMLs were isolated from blood samples, and PD-L1 expression was categorized as low or high.
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).
- 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 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," stated Giuseppe Del Priore, MD, MPH, BriaCell's Chief Medical Officer. "Further studies are needed to validate CAML PD-L1 as a predictive biomarker."
About BriaCell's Pivotal Phase 3 Clinical Study of Bria-IMT Combination Regimen in MBC patients
BriaCell's pivotal Phase 3 study of Bria-IMT plus an immune check point 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. BriaCell reported positive Phase 2 survival data in a similar MBC patient population treated with the same Bria-IMT combination regimen. The Bria-IMT combination regimen has received FDA Fast Track designation.
For additional information on BriaCell's pivotal Phase 3 study of Bria-IMT and an immune check point inhibitor in metastatic breast cancer, please visit ClinicalTrials.gov NCT06072612.
A copy of the poster presentation is available at https://briacell.com/scientific-publications/.
About briacell therapeutics corp.
BriaCell is an immuno-oncology-focused biotechnology company developing targeted and effective approaches for the management of cancer. More information is available at https://briacell.com/.
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Contact Information
Company Contact:
William V. Williams, MD
President & CEO
1-888-485-6340
info@briacell.comÂ
Investor Relations Contact:
investors@briacell.com
