Adjuvant PD-1 and PD-L1 Inhibitors and Relapse-Free Survival in Cancer Patients: The MOUSEION-04 Study

SIMPLE SUMMARY: Despite a significant improvement in clinical outcomes and the emergence of novel and potentially curative strategies, a noticeable number of oncological patients witness a disease relapse after surgery. Adjuvant treatments have been developed to reduce the risk of recurrence and gain survival benefits for these patients. The aim of this meta-analysis was to explore the impact of adjuvant PD-1/PD-L1 inhibitors on relapse-free survival in cancer patients with many solid tumors. We confirmed that PD-1/PD-L1 inhibitors may reduce the risk of relapse in many tumor types, compared to control treatments. Moreover, we showed that the benefit was consistent in subgroups divided according to gender and age. ABSTRACT: Background: Adjuvant treatment has always been a cornerstone in the therapeutic approach of many cancers, considering its role in reducing the risk of relapse and, in some cases, increasing overall survival. Adjuvant immune checkpoint inhibitors have been tested in different malignancies. Methods: We performed a meta-analysis aimed to explore the impact of adjuvant PD-1 and PD-L1 inhibitors on relapse-free survival (RFS) in cancer patients enrolled in randomized controlled clinical trials. We retrieved all phase III trials published from 15 June 2008 to 15 May 2022, evaluating PD-1/PD-L1 inhibitors monotherapy as an adjuvant treatment by searching on EMBASE, Cochrane Library, and PubMed/ Medline, and international oncological meetings’ abstracts. The outcome of interest was RFS. We also performed subgroup analyses focused on age and gender. Results: Overall, 8 studies, involving more than 6000 patients, were included in the analysis. The pooled results highlighted that the use of adjuvant PD-1/PD-L1 inhibitors may reduce the risk of relapse compared to control treatments (hazard ratio, 0.72; 95% confidence intervals, 0.67–0.78). In addition, the subgroup analyses observed that this benefit was consistent in different patient populations, including male, female, younger, and older patients. Conclusions: Adjuvant anti-PD-1/PD-L1 treatment is associated with an increased RFS in the overall population and in subgroups divided according to age and gender.