Fig. 6: PBRM1 loss induces resistance to ICB.

a Early treatment with anti-PD-1 blockade. PD-1 antibodies were administrated at day 3, day 6, and day 9 after tumor inoculation. First dose was 400 µg/mouse, and the following two doses were 200 µg/mouse. b Delayed treatment with anti-PD-1 blockade. Anti-PD-1 antibody (200 µg/mouse) was administrated every third day once the tumors reached 100-200 mm³. Treatment schemas, In vivo tumor growth rates and survival rates of mice are shown. Two-way ANOVA and Log-rank (Mantel-Cox) analyses were performed with GraphPad Prism 7.03. Data in the graphs are means ± SEM. UnTX, untreated control. ns, P > 0.05, *P < 0.05, and **P < 0.001. c Patient response in the IMmotion150 cohort following treatment with either atezolizumab (Atezo) or atezolizumab in combination with bevacizumab (Atezo + Bev). Mono, PBRM1 mutation only, Dual, PBRM1 mutation in combination with a BAP1 or SETD2 mutation; WT, wild type; CR, complete response; PR, partial response; SD, stable disease; PD, progressive disease. Cochran–Mantel–Haenszel test. d Comparison of patient response rate, defined as either a complete or partial response, in the IMmotion150 cohort. Cochran–Mantel–Haenszel test. e Overall survival of RCC patients treated with ICB from the MSKCC IMPACT cohort stratified by PBRM1 status. Log-rank test. f Overall survival of ccRCC patients from TCGA stratified by PBRM1 mutation status. Log-rank test. g Model for PBRM1 mediated IFNγ-STAT1 signaling and tumor immune microenvironment modulating. PBRM1 ensures IFNγ-induced STAT1 activity and autonomous expression of downstream genes involved in T-cell recruitment (e.g., CXCL9). Infiltrating, activated T cells in turn produce more IFNγ which stimulates tumor cells to secrete immunostimulatory chemokines and cytokines, and in parallel upregulate checkpoint pathways on T cells and tumors cells. Thus, the immunogenic TME of PBRM1 proficient tumors is primed to respond to ICB. On the other hand, PBRM1 loss reduces IFNγ-STAT1 signaling and downstream T cell attracting factors, which prevents T cell infiltration and IFNγ secretion. Such a non-immunogenic TME of PBRM1 mutated tumors blunts ICB response. Source data are provided as a Source Data file.