Anti-PD-1 therapy with inhibitors such as pembrolizumab has proven beneficial for multiple types of cancers. Not all patients respond to PD-1 blockade; therefore, strategies to better predict individual response to anti-PD-1 would be of great clinical benefit. In this episode, Terri McClanahan and Jared Lunceford discuss their work, which has led to the identification of a gene expression profile that correlates with clinical response to pembrolizimab. Importantly, the presence of this T cell-inflamed gene expression profile in patients prior to treatment was shown to be indicative of response in multiple cohorts and cancer types.
Programmed death-1–directed (PD-1–directed) immune checkpoint blockade results in durable antitumor activity in many advanced malignancies. Recent studies suggest that IFN-γ is a critical driver of programmed death ligand-1 (PD-L1) expression in cancer and host cells, and baseline intratumoral T cell infiltration may improve response likelihood to anti–PD-1 therapies, including pembrolizumab. However, whether quantifying T cell–inflamed microenvironment is a useful pan-tumor determinant of PD-1–directed therapy response has not been rigorously evaluated. Here, we analyzed gene expression profiles (GEPs) using RNA from baseline tumor samples of pembrolizumab-treated patients. We identified immune-related signatures correlating with clinical benefit using a learn-and-confirm paradigm based on data from different clinical studies of pembrolizumab, starting with a small pilot of 19 melanoma patients and eventually defining a pan-tumor T cell–inflamed GEP in 220 patients with 9 cancers. Predictive value was independently confirmed and compared with that of PD-L1 immunohistochemistry in 96 patients with head and neck squamous cell carcinoma. The T cell–inflamed GEP contained IFN-γ–responsive genes related to antigen presentation, chemokine expression, cytotoxic activity, and adaptive immune resistance, and these features were necessary, but not always sufficient, for clinical benefit. The T cell–inflamed GEP has been developed into a clinical-grade assay that is currently being evaluated in ongoing pembrolizumab trials.
Mark Ayers, Jared Lunceford, Michael Nebozhyn, Erin Murphy, Andrey Loboda, David R. Kaufman, Andrew Albright, Jonathan D. Cheng, S. Peter Kang, Veena Shankaran, Sarina A. Piha-Paul, Jennifer Yearley, Tanguy Y. Seiwert, Antoni Ribas, Terrill K. McClanahan