Comprehensive molecular analysis identifies RET alterations association with response of ICIs in multi-immunotherapy cohorts

Background: The RET gene, which is frequently mutated across many types of cancer, has been proven to be critically involved in tumorigenesis and tumour development; however, its prediction of the therapeutic efficacy of immune checkpoint inhibitor (ICI) therapy remains to be elucidated. The present research aims to investigate the association between RET mutations and the efficiency of ICI therapy.

Method: We analysed the role of RET mutations in predicting the prognosis of patients receiving ICIs therapy in the discovery cohort and validated it in the validation cohort. Then, multi-omics data from TCGA pan-cancer cohort was employed to propose the association between RET mutations and tumour inflamed anti-tumour immune response and tumour antigenicity.

Results: Our study revealed that among 606 cases and across five types of cancer, RET mutation was associated with better clinical outcomes for ICIs therapy, including elevated response rate, longer progression-free survival PFS, and longer overall survival OS. Multivariate analysis showed that RET mutation could independently predict the prognosis of patients treated with ICIs, after adjusting cancer types. The predictive value of RET status for the OS of patients treated with ICIs immunotherapy was further validated in the validation cohort (n = 1,409). Subgroup analysis suggested that only the monotherapy group showed significant differences in OS(P < 0.05) and PFS(P < 0.05) between RET-wildtype tumours and RET-mutant tumours. Multi-omics data analysis revealed potential anti-tumour immunity mechanisms of RET mutations, suggesting that RET-mutant tumours have enhanced immunogenicity, higher expression of immune checkpoints and chemokines, and higher immune cell infiltration than those observed in RET-wildtype tumours; thus, potentially indicating a more favourable response to immunotherapy.

Conclusions: RET mutation may be a predictive biomarker of enhanced response to ICIs therapy. Extensive investigation of the underlying molecular mechanisms and prospective studies are needed in the future.