Prevalence of Secondary Immunotherapeutic Targets in the Absence of Established Immune Biomarkers in Solid Tumors

SITC 2021 -- Immune checkpoint inhibitor-based therapies have achieved impressive success in the treatment of several cancer types. Predictive immune biomarkers, including PD-L1 by immunohistochemistry (IHC), microsatellite instability (MSI) and tumor mutational burden (TMB) are well established as surrogate markers for immune evasion and tumor-specific neoantigens across many tumors. Positive detection across cancer types varies but overall, approximately 50% of patients test negative for these primary immune biomarkers. In this study, we investigated the prevalence of secondary immune biomarkers outside of PD-L1 IHC, TMB and MSI.