Pretreatment tumor PD-L1 expression has been shown to correlate with response to anti–PD-1/PD-L1 therapies. Yet, most patients with PD-L1⁺ tumors do not respond to treatment. The current study was undertaken to investigate mechanisms underlying the failure of PD-1–targeted therapies in patients with advanced renal cell carcinoma (RCC) whose tumors express PD-L1. Formalin-fixed, paraffin-embedded pretreatment tumor biopsies expressing PD-L1 were derived from 13 RCC patients. RNA was isolated from PD-L1⁺ regions and subjected to whole genome microarray and multiplex quantitative (q)RT-PCR gene expression analysis. A balance between gene expression profiles reflecting metabolic pathways and immune functions was associated with clinical outcomes following anti–PD-1 therapy. In particular, the expression of genes involved in metabolic and solute transport functions such as UGT1A family members, also found in kidney cancer cell lines, was associated with treatment failure in patients with PD-L1⁺ RCC. Conversely, tumors from responding patients overexpressed immune markers such as BACH2, a regulator of CD4⁺ T-cell differentiation, and CCL3 involved in leukocyte migration. These findings suggest that tumor cell–intrinsic metabolic factors may contribute to treatment resistance in RCC, thus serving as predictive markers for treatment outcomes and potential new targets for combination therapy regimens with anti–PD-1. Cancer Immunol Res; 4(9); 726–33. ©2016 AACR.

See related Spotlight by Ohashi, p. 719.