Multinational phase 3 trial of atezolizumab plus chemotherapy for advanced or recurrent endometrial cancer

The phase 3 AtTEnd trial, at 89 centers in 11 countries, evaluated addition of atezolizumab to carboplatin-paclitaxel chemotherapy for advanced or recurrent (A/R) endometrial cancer. Patients were randomized 2:1 to atezolizumab plus chemotherapy or placebo plus chemotherapy. Among patients with dMMR disease (23% of the patients), the median PFS was not reached in the atezolizumab group and 6.9 months in the placebo group (HR 0.36; p=0.0005). In the overall population, the median PFS was 10.1 months in the atezolizumab group and 6.9 months in the placebo group (HR 0.74; p=0.022). Median overall survival was 38.7 months in the atezolizumab group and 30.2 months in the placebo group (HR 0.82; p=0.048). The most-common grade 3 or 4 treatment-related adverse events were neutropenia (27% in the atezolizumab group and 28% in the placebo group) and anemia (14% versus 13%). In each group one patient died of treatment-related pneumonia. The authors conclude that addition of atezolizumab to chemotherapy was associated with improved progression-free survival among patients with A/R endometrial carcinoma, particularly among those with dMMR carcinoma.