PPP2R1A mutations portend improved survival after cancer immunotherapy.

Immune checkpoint blockade (ICB) therapy is effective against many cancers, although resistance remains a major issue and new strategies are needed to improve clinical outcomes1-5. Here we studied ICB response in a cohort of patients with ovarian clear cell carcinoma-a cancer type that poses considerable clinical challenges and lacks effective therapies6-8. We observed significantly prolonged overall survival and progression-free survival in patients with tumours with PPP2R1A mutations. Importantly, our findings were validated in additional ICB-treated patient cohorts across multiple cancer types. Translational analyses from tumour biopsies demonstrated enhanced IFNγ signalling, and the presence of tertiary lymphoid structures at the baseline, as well as enhanced immune infiltration and expansion of CD45RO+CD8+ T cells in the tumour neighbourhood after ICB treatment in PPP2R1A-mutated tumours. Parallel preclinical investigations showed that targeting PPP2R1A (by pharmacological inhibition or genetic modifications) in in vitro and in vivo models was associated with improved survival in the setting of treatment with several forms of immunotherapy, including chimeric antigen receptor (CAR)-T cell therapy and ICB. The results from these studies suggest that therapeutic targeting of PPP2R1A may represent an effective strategy to improve patient outcomes after ICB or other forms of immunotherapy, although additional mechanistic and therapeutic insights are needed.