Functional hotness score based on three genes predicts long-term survival of triple-negative breast cancer independent from tumor mutational burden.

Abstract

e12583 Background: Cytotoxic T-lymphocytes (CTLs) infiltration into tumor is a positive prognostic factor in breast cancer. Infiltration of CTLs are believed to be driven by mutation-induced neoantigens, thus, higher tumor mutation burden (TMB) is considered an important predictor of tumor immunogenicity and response to immunotherapy, but the association between intratumoral CTL counts and TMB in the overall cancer prognosis remains unclear. Methods: Utilizing publicly available breast cancer cohorts, we established Functional Hotness Score (FHS), based on CD8A, GZMB and CXCL10 gene expression levels of bulk tumors. The associations of FHS and breast cancer patient prognosis as well as distinct immunity markers were analyzed. Results: Breast cancer patients with high-FHS tumors demonstrated significantly better survival. FHS was lower in metastatic breast cancer. Among breast cancer subtypes, triple-negative breast cancer (TNBC) showed the highest FHS. FHS predicted patient survival not in hormone receptor (HR)-positive but in HR-negative, especially TNBCs. The high-FHS TNBCs enhanced not only CD8+ T cell infiltration, but also a broader type-1 anti-cancer immunity. The patients with the high-FHS patients showed better prognosis not only in high-TMB tumors but also in low-TMB TNBCs. The combination of high-TMB with high-FHS identified the unique subset of patients who did not recur over time. Conclusions: In conclusion, TNBCs with high-FHS based on the expression levels of CD8A, GZMB and CXCL10 showed improved prognosis with higher anti-cancer immunity regardless of TMB, and constituting an independent prognostic marker of survival, particularly robust when combined with TMB.