Incorporation of anti-PD1 or anti PD-L1 agents to platinum-based chemotherapy for the primary treatment of advanced or recurrent endometrial cancer. A meta-analysis

Importance: Various randomized trials have explored the efficacy of combining immune checkpoint inhibitors (ICIs) with first-line chemotherapy in advanced endometrial cancer. We aimed to summarize available data and clarify the benefit of adding immunotherapy according to the DNA mismatch repair status (deficient, dMMR or proficient, pMMR) and the specific type of agent used (anti-PD1 or anti-PD-L1). Objective: To assess whether the addition of ICIs to standard platinum-based chemotherapy enhances progression-free survival (PFS) for patients with advanced endometrial cancer both overall and based on DNA mismatch repair status. Data sources: Electronic databases (PubMed, Embase and Cochrane Library) and conference proceedings were searched for first line, randomized and controlled trials integrating ICIs with chemotherapy for the treatment of advanced endometrial cancer published or presented by November 1, 2023. Study selection: Five studies, comprising 2456 patients (1308 received ICIs with chemotherapy and 1148 treated with chemotherapy alone) met the selection criteria and were included in the analysis. Experimental arms included pembrolizumab, dostarlimab (anti-PD1) and durvalumab, atezolizumab and avelumab (anti-PD-L1) combined with standard three-weekly carboplatin-paclitaxel chemotherapy backbone. Endometrial carcinosarcoma were included in 3 out of 5 trials. Data extraction and synthesis: For comparison of PFS outcomes, extrapolation of hazard ratios (HRs), 95% confidence intervals (CI) and PFS events was performed for each included study in the overall population and according to subgroups. Data analysis was conducted using a random-effects model. Results: The addition of ICIs to chemotherapy improved PFS compared to chemotherapy alone in the overall population (pooled HR, 0.63; 95 % CI, 0.52--0.76; P <.001). In the dMMR subgroup the benefit was more pronounced (pooled HR, 0.34; 95 % CI, 0.27--0.44; P <.001) and not affected by drugs used with pooled HRs of 0.39 (95 % CI, 0.28--0.55; P <.001) and 0.34 (95 % CI, 0.27--0.44; P <.001) for PD-L1 and PD1 inhibitors, respectively. For pMMR patients, a statistically significant benefit in terms of PFS was confirmed only when anti-PD1 were used (anti-PD-1: HR 0.64, 95 % CI: 0.46-0.90, P =.010 vs anti-PD-L1: HR 0.87, 95 % CI: 0.73-1.03, P =.104) CONCLUSIONS AND RELEVANCE: This meta-analysis confirmed the advantage in terms of PFS of adding ICIs to standard platinum-based chemotherapy. While dMMR patients benefit from the incorporation of both anti PD-1 or anti PD-L1, this benefit is confined to the association of anti-PD1 agents in pMMR patients. Updated analysis of trials is awaited to clarify the impact of immunotherapy on overall survival.