ESMO Congress 2026

First-line treatment decisions in metastatic breast cancer already follow a relatively clear real-world logic. A cross-sectional survey of 250 US oncologists showed that efficacy and safety/tolerability are critical in first-line decision-making for HR+/HER2- metastatic breast cancer; CDK4/6 inhibitor use correlated positively with the proportion of Medicare and postmenopausal patients (r=0.54-0.67), while chemotherapy correlated with perimenopausal/premenopausal patients and symptom burden (r=0.31-0.42) ^[2]. Meanwhile, drug resistance remains a major obstacle leading to treatment failure and high mortality, and CCNE1/CCNE2 amplifications are associated with resistance to targeted therapies, immunotherapy, endocrine therapies and chemo/radiotherapy ^[1]. Together these form the backdrop for reading the current data: under the dual pressure of efficacy and resistance, there is a real-world need for circulating biomarkers that can dynamically reflect benefit from immunotherapy.

At this congress, BriaCell announced that it will present clinical biomarker findings from a prospective pooled analysis at the ESMO26 Congress, taking place October 23-27, 2026 in Madrid, Spain: the analysis pools data from several studies of patients with metastatic breast cancer treated with immune-based therapies including the BriaCell regimen, and includes BriaCell's Phase 1/2 Bria-IMT study. The company also highlights CAML PD-L1 as a potential biomarker of clinical outcomes in metastatic breast cancer; Dr. William V. Williams, BriaCell's President and CEO, stated 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. The posts disclose no specific numbers such as patient counts or hazard ratios.

In terms of incremental value, this reading advances the biomarker dimension: it attempts to link a dynamically monitorable circulating immune biomarker (CAML PD-L1) to both progression-free and overall survival after immunotherapy, rather than updating efficacy endpoints. Against a backdrop where first-line decisions rely heavily on efficacy and safety evidence ^[2] and multiple treatment classes including immunotherapy face resistance ^[1], if this biomarker is subsequently validated, its potential value lies in selecting patients more likely to benefit from immunotherapy and enabling dynamic prediction of treatment response.

The limitations are equally clear: the data come from a pooled analysis, and the included Bria-IMT study is only Phase 1/2, without randomized Phase 3 validation; CAML PD-L1 is so far described only as a potential biomarker, and the posts provide only a qualitative description of the association, lacking effect sizes, sample sizes and statistical details — its clinical utility can only be judged after the full data are disclosed at the congress.