First-line lenvatinib plus pembrolizumab versus chemotherapy for advanced endometrial cancer: 1-Year follow-up after final analysis of the ENGOT-en9/LEAP-001 phase 3 trial.

[OBJECTIVE] The phase 3 ENGOT-en9/LEAP-001 trial (NCT03884101) comparing first-line lenvatinib+pembrolizumab with carboplatin+paclitaxel did not meet pre-specified statistical criteria for overall survival or progression-free survival in participants with advanced/recurrent endometrial cancer. We report results after an additional year of follow-up (overall median 54.5 [range; 46.5-69.0] months).

[METHODS] Eligible participants were adult females with stage III to IV or recurrent, histologically confirmed endometrial cancer. Measurable or non-measurable disease per Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 and radiographically apparent disease per blinded independent central review was required. Participants were randomly allocated 1:1 to lenvatinib+pembrolizumab or chemotherapy (paclitaxel+carboplatin). The primary end points were overall survival and progression-free survival per RECIST version 1.1 by blinded independent central review. Secondary end points included objective response rate per RECIST version 1.1 by blinded independent central review and safety.

[RESULTS] The median overall survival (95% confidence interval [CI]) was 30.9 (range; 25.4-37.6) months with lenvatinib+pembrolizumab versus 29.4 (range; 26.2-34.8) months with chemotherapy in mismatch repair-proficient endometrial cancer (hazard ratio [HR] 0.99, 95% CI 0.82 to 1.21), 37.9 (range; 32.2-43.0) versus 32.3 (range; 27.2-35.7) months in all-comers (HR 0.91, 95% CI 0.77 to 1.09), and not reached in either treatment group in mismatch repair-deficient endometrial cancer (HR 0.60, 95% CI 0.39 to 0.93]). Corresponding results for progression-free survival were 9.6 (range; 8.2-11.9) versus 10.2 (range; 8.4-10.5) months (HR 1.01, 95% CI 0.83 to 1.22), 12.5 (range; 10.3-15.1) versus 10.2 (range; 8.4-10.4) months (HR 0.92, 95% CI 0.77 to 1.10]), and 31.8 (22.5 to not reached) versus 9.0 (range; 8.2-17.1) months (HR 0.62, 95% CI 0.41-0.93). Objective response rates were 50.6% versus 54.7%, 55.7% versus 55.5%, and 72.0% versus 58.0%, respectively. No new safety signals were identified. The results were consistent with those at the final analysis.

[CONCLUSIONS] The mismatch repair-proficient, all-comer, and mismatch repair-deficient populations continued to demonstrate antitumor activity for lenvatinib+pembrolizumab after an additional year of follow-up. These results should be interpreted with caution due to the exploratory nature of the analysis.

[TRIAL REGISTRATION] ClinicalTrials.gov No. NCT03884101.