63 Th17 Signature Predicts Response to Dual Checkpoint Blockade in Metastatic Renal Cell Carcinoma

Abstract

Abstract Background Combination immune checkpoint inhibition with anti-CTLA-4 and anti-PD-1 antibodies improves outcomes in metastatic renal cell carcinoma (mRCC), yet 40–60% of patients fail to achieve meaningful responses. Robust biomarkers that predict deep and durable responses are lacking. We aimed to define systemic and tumor-associated immune signatures associated with therapeutic efficacy using an integrated multi-omic approach. Methods We analyzed peripheral blood and tumor samples from patients with intermediate- and poor-risk mRCC enrolled in a phase II clinical trial evaluating a response-adapted regimen of nivolumab and ipilimumab (NCT03297593, SAKK07/17). High-dimensional mass cytometry was used to profile immune cell populations. Single-cell proteomic and transcriptomic profiling was performed using CITE-seq, and bulk RNA sequencing was conducted on tumor biopsies. Imaging mass cytometry enabled spatial validation within the tumor microenvironment. Differential abundance, gene expression, and pathway analyses were integrated across datasets to identify correlates of response. Results Among evaluable patients, 16 of 24 achieved partial or complete responses, while 8 exhibited stable or progressive disease. Responders demonstrated a significant expansion of CD4+CCR6+ Th17 cells in peripheral blood following therapy, accompanied by increased CD8 effector memory T cells and dendritic cell subsets. Single-cell multi-omic analysis revealed enrichment of Th17-associated transcriptional programs. Pseudotime analysis showed a delayed transition from naïve CD4+ T cells to Th17 cells in non-responders, associated with anti-inflammatory gene signatures, suggesting impaired immune activation. Spatial profiling using imaging mass cytometry validated increased infiltration of CD4+CCR6+ Th17 cells within responder tumors, alongside enhanced immune cell colocalization and reduced stromal features. In contrast, non-responders exhibited immune-excluded, stroma-rich tumor microenvironments. Notably, tumor mutational features, including PBRM1, BAP1, and VHL alterations, did not correlate with response in this cohort. Conclusions A Th17-centric immune signature is strongly associated with deep and sustained responses to dual checkpoint blockade in mRCC. These findings highlight Th17 cells as key mediators of antitumor immunity and potential predictive biomarkers. Integrating systemic and tumor immune profiling provides a framework for patient stratification and the development of therapeutic strategies to overcome resistance. DOD CDMRP Funding yes