SETD2 loss and ATR inhibition synergistically promote cGAS signaling and immunotherapy response in renal cell carcinoma

Immune checkpoint blockade (ICB) demonstrates durable clinical benefit only in a minority of renal cell carcinoma (RCC) patients. Identifying molecular features that determine response and developing approaches to enhance the response remain an urgent clinical need. Here we found that, in multiple RCC cell lines, targeting the ATR-CHK1 axis with pharmacological inhibitors increased cytosolic DNA accumulation, activated the cGAS-IRF3-dependent cytosolic DNA sensing pathway, and resulted in the inflammatory cytokine expression. SETD2 mutated RCC cell lines or tumor samples were associated with preferential ATR-CHK1 activation over ATM-CHK2 activation. SETD2 knockdown promoted the cytosolic DNA sensing pathway and conferred greater sensitivity in response to ATR-CHK1 inhibition. In murine Renca tumors, Setd2 knockdown and ATR inhibitor VE822 synergistically promoted cytosolic DNA sensing pathway, immune cell infiltration, and immune checkpoint protein expression. Setd2 deficient Renca tumors demonstrated greater vulnerability to ICB monotherapy or in combination with VE822 than Setd2 proficient tumors. SETD2 mutations were associated with a higher response rate and prolonged overall survival in ICB-treated RCC patients, but not in non-ICB-treated RCC patients. This study provides a mechanism-based guidance to develop more personalized combination therapy regimens for RCC patients with SETD2 mutations. Cell line data: 786-O parental cell lines were treated with LY2606368 (a CHK1 inhibitor) treatment or no treatment (control), in two separate experiments Murine tumor data: