Abstract 66P
Background
Recent studies have shown that the tumor microenvironment can shape the response to immune-modulating therapies. Anthracyclines are a major chemotherapy regimen for breast cancer that induce immunogenic cell death. We hypothesized that patients with “immune hot” tumors may benefit from anthracyclines more than patients with “immune cold” tumors.
Methods
As one of the largest breast cancer studies using the GeoMx digital spatial profiling, we tested this hypothesis by profiling 35 biomarkers on 536 cases obtained from the Canadian Cancer Trials Group MA.5 phase III clinical trial. In this trial, node-positive breast cancer patients were randomized to receive either a cyclophosphamide-based (cyclophosphamide-methotrexate-fluorouracil (CMF)) or anthracycline-containing adjuvant chemotherapy (cyclophosphamide-epirubicin-fluorouracil (CEF)). Tissue microarray sections were stained with barcoded antibodies to obtain digitally quantified biomarker counts.
Results
Unsupervised hierarchical clustering revealed two patient clusters: immune infiltrated and ignored. Following a pre-specified statistical plan crafted to meet ReMARK (REporting recommendations for tumor MARKer prognostic studies) guidelines, we did not observe significant results for the primary hypotheses: Immune cluster assignment did not predict an improved 10-year relapse-free survival or overall survival for patients receiving CEF compared to CMF in the full cohort. However, some of our secondary hypotheses revealed a significant predictive value for immune cluster assignment and stromal tumor infiltrating lymphocytes assessed on hematoxylin and eosin (H&E)-stained sides for CEF benefit over CMF in the human epidermal growth factor receptor 2 (HER2)-enriched subset. As an exploratory analysis, supervised clustering of immune biomarkers suggested that low levels of TIM-3 and high levels of HLA-DR and PD-L1 were associated with an extra benefit from CEF compared with CMF.
Conclusions
While novel multiplexing techniques provide a detailed insight into the tumor microenvironment, conventional H&E staining acts as a powerful tool to assess the value of immune microenvironment in predicting benefits from immunogenic chemotherapies.
Legal entity responsible for the study
The authors.
Funding
Our study is funded by the Canadian Cancer Society, grant number 705463; Canada Foundation for Innovation / John R. Evans Leaders Fund in collaboration with the UBC Department of Pathology and Laboratory Medicine British Columbia Knowledge Development Fund (BCKDF). First author is supported by BC Cancer Rising Star Award and by IOP travel award.
Disclosure
Z. Kos: Financial Interests, Institutional, Advisory Role, not related to this project: AstraZeneca Canada, Eli Lilly Canada. T.O. Nielsen: Financial Interests, Institutional, Proprietary Information, Licensed to Veracyte technologies through Bioclassifier LLC.: Prosigna. All other authors have declared no conflicts of interest.