Efficacy and Safety of Benmelstobart Plus Anlotinib in Advanced Endometrial Cancer: Results of a Multi-Cohort, Phase II Study (ETER200)

Patients with advanced endometrial cancer (EC) have a poor prognosis and limited therapeutic options after failure of prior systemic therapy. In this multi-cohort Phase II study (ETER200), patients with metastatic or recurrent EC who had received at least one chemotherapy regimen were enrolled. Based on MSI/MMR status, patients received benmelstobart plus anlotinib (Cohort 1), benmelstobart (Cohort 2), or anlotinib (Cohort 3) every 3 weeks. Primary endpoint was objective response rate (ORR) assessed by independent review committee (IRC) per RECIST v1.1. Here, the results of Cohort 1 expansion stage were reported. As of May 9, 2024, 85 of the 107 non-MSI-H/pMMR EC patients enrolled in Cohort 1 constituted the expansion stage population for primary efficacy analysis. The IRC-assessed ORR was 34.1% (95% CI, 24.2-45.2), with a median duration of response of 15.2 months (95% CI, 6.9-not evaluable). Median progression-free and overall survival were 8.8 months (95% CI, 5.8-15.2) and 21.8 months (95% CI, 19.5-29.1), respectively. Grade ≥ 3 treatment-related adverse events occurred in 69.2% of patients, most commonly hypertension (21.2%) and palmar-plantar erythrodysesthesia syndrome (9.4%). Overall, benmelstobart plus anlotinib showed promising anti-tumor activity and an acceptable safety profile in advanced non-MSI-H/pMMR EC, supporting further evaluation of this combination in randomized Phase III studies. Trial Registration: ClinicalTrials.gov, NCT04574284.