Efficacy and safety of HDACIs in the treatment of metastatic or unresectable renal cell carcinoma with a clear cell phenotype A systematic review and meta-analysis

Background: In this study, we evaluated the efficacy and safety of histone deacetylase inhibitors (HDACIs) in the treatment of renal cell carcinoma (RCC). Methods: PubMed, EMBASE, the Cochrane Library, CNKI, and the Wanfang database were searched to retrieve studies describing the use of HDACIs for the treatment of RCC published between January 1, 2009, and January 1, 2021. Relevant studies were selected, and data were extracted. Then, a meta-analysis was performed using R 3.5.2 software. Results: The results showed that the objective response rate (ORR) of HDACIs used to treat RCC was 26% [95% confidence interval (95% CI): 0.19 similar to 0.34] and that the 1-year progression-free survival (PFS) rate was 29% (95% CI: 0.14 similar to 0.59). The ORR and PFS rate of the combination group were better than those of the monotherapy group, and the ORR and PFS rate of the selective HDACI group were better than those of the pan-HDACI group. The incidences of neutropenia and thrombocytopenia were higher and the incidence of fatigue was lower in the selective HDACI group than in the pan-HDACI group. Conclusion: This study initially confirmed the efficacy and safety of HDACIs for the treatment of RCC. Due to the limitations of the included studies, more high-quality studies are needed to validate the conclusions.