40P - Intra-tumoral CD3, CD4, and CD8 as prognostic biomarkers in Asian breast cancer

Background

Recent evidence suggests that breast cancer may have population-specific characteristics, including differences in the tumour immune microenvironment (TME). Immune cell markers in the TME, particularly CD8, may have utility as predictive and prognostic biomarkers, but there is conflicting evidence from previous studies. The aim of this study was to determine the prognostic utility of immune cell immunohistochemistry markers in tumor samples from a cohort of breast cancer patients from Malaysia.

Methods

We obtained digitized whole slide images of breast tumour tissue samples stained for CD3, CD4, CD8, and PD-L1 markers for 576 breast cancer patients from Subang Jaya Medical Centre, a Malaysian private hospital. These patients were included in the Malaysian Breast Cancer (MyBrCa) study cohort, and thus multi-omics data were also available for analysis for each patient. We also obtained overall survival data from the Malaysian national registry for this group of patients, with a median follow-up time of 68 months.

Results

We compared the intra-tumoral scores for each marker to overall survival data and found that the scores for CD3, CD4, and CD8, but not PD-L1, were positively associated with overall survival, particularly for patients with triple-negative breast cancer (TNBC). Additionally, the CD3, CD4, and CD8 scores were not associated with tumour mutational burden (TMB) or neoantigen load and had a negative correlation with copy number aberrations.

Conclusions

Our results suggest that intra-tumoral markers for T-cells are indicative of good prognosis in Asian breast cancer. Our results also suggest that the TME in Asian breast cancer may be shaped by non-canonical pathways.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Cancer Research Malaysia.

Funding

Cancer Research Malaysia, Yayasan PETRONAS, Yayasan Sime Darby, Scientex Foundation, Estee Lauder Companies, Vistage Malaysia, Newton-Ungku Omar Fund.

Disclosure

All authors have declared no conflicts of interest.