Efficacy of PD-1 Inhibitor Combined with Bevacizumab in Treatment of Advanced Endometrial Cancer Patients with Mismatch Repair Deficiency (dMMR)/High-Level Microsatellite Instability (MSI-H).

BACKGROUND Mismatch repair deficiency (dMMR) is associated with endometrial cancers, yet it remains unknown how this information could be incorporated into adjuvant treatment paradigms. We performed this cohort study to identify the effect of dMMR status on the prognosis of patients with advanced endometrial cancer treated with PD-1 inhibitor and bevacizumab. MATERIAL AND METHODS We enrolled 93 patients with advanced endometrial cancer and divided them into an observation group (n=52) and a control group (n=41) according to the treatment. The control group was treated with bevacizumab combined with paclitaxel chemotherapy, while the observation group was treated with PD-1inhibitor combined with bevacizumab. The basic characteristics and overall survival times were compared between the 2 groups. RESULTS There was no significant difference in age, course of disease, clinical stage, or pathological type. The proportion of patients with dMMR and high-level microsatellite instability (MSI-H) were balanced in the 2 groups. Patients in the observation group had longer overall survival than those in the control group (33.2 months vs 21.8 months). Moreover, in the observation group, the median OS of dMMR patients was not detected, while the median OS of PMMR patients was 29.2 months (P<0.01). In the control group, the median OS of dMMR patients was 12.4 months, and that of PMMR patients was 24.1 months (P<0.01). CONCLUSIONS Advanced endometrial cancer patients with dMMR/MSI-H treated with PD-1 inhibitor plus bevacizumab had longer overall survival (OS) than those treated with bevacizumab plus paclitaxel chemotherapy.