PURPOSE Patients with advanced endometrial carcinoma have limited treatment options. We report final primary efficacy analysis results for a patient cohort with advanced endometrial carcinoma receiving lenvatinib plus pembrolizumab in an ongoing phase Ib/II study of selected solid tumors. METHODS Patients took lenvatinib 20 mg once daily orally plus pembrolizumab 200 mg intravenously once every 3 weeks, in 3-week cycles. The primary end point was objective response rate (ORR) at 24 weeks (ORRWk24); secondary efficacy end points included duration of response (DOR), progression-free survival (PFS), and overall survival (OS). Tumor assessments were evaluated by investigators per immune-related RECIST. RESULTS At data cutoff, 108 patients with previously treated endometrial carcinoma were enrolled, with a median follow-up of 18.7 months. The ORRWk24 was 38.0% (95% CI, 28.8% to 47.8%). Among subgroups, the ORRWk24 (95% CI) was 63.6% (30.8% to 89.1%) in patients with microsatellite instability (MSI)–high tumors (n = 11) and 36.2% (26.5% to 46.7%) in patients with microsatellite-stable tumors (n = 94). For previously treated patients, regardless of tumor MSI status, the median DOR was 21.2 months (95% CI, 7.6 months to not estimable), median PFS was 7.4 months (95% CI, 5.3 to 8.7 months), and median OS was 16.7 months (15.0 months to not estimable). Grade 3 or 4 treatment-related adverse events occurred in 83/124 (66.9%) patients. CONCLUSION Lenvatinib plus pembrolizumab showed promising antitumor activity in patients with advanced endometrial carcinoma who have experienced disease progression after prior systemic therapy, regardless of tumor MSI status. The combination therapy had a manageable toxicity profile.

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PURPOSE Modulation of vascular endothelial growth factor–mediated immune suppression via angiogenesis inhibition may augment the activity of immune checkpoint inhibitors. We report results from the dose-finding and initial phase II expansion of a phase Ib/II study of lenvatinib plus pembrolizumab in patients with selected advanced solid tumors. METHODS Eligible patients had metastatic renal cell carcinoma (RCC), endometrial cancer, squamous cell carcinoma of the head and neck (SCCHN), melanoma, non–small-cell lung cancer (NSCLC), or urothelial cancer. The primary objective of phase Ib was to determine the maximum tolerated dose (MTD) for lenvatinib plus pembrolizumab (200 mg intravenously every 3 weeks). In the preplanned phase II cohort expansion, the primary objective was objective response rate at week 24 (ORRweek 24) at the recommended phase II dose. RESULTS Overall, 137 patients were enrolled during phase Ib (n = 13) and the initial phase II expansion (n = 124). Two dose-limiting toxicities (DLTs; grade 3 arthralgia and grade 3 fatigue) were reported in the initial dose level (lenvatinib 24 mg/d plus pembrolizumab). No DLTs were observed in the subsequent dose–de-escalation cohort, establishing the MTD and recommended phase II dose at lenvatinib 20 mg/d plus pembrolizumab. ORRweek24 was as follows: RCC, 63% (19/30; 95% CI, 43.9% to 80.1%); endometrial cancer, 52% (12/23; 95% CI, 30.6% to 73.2%); melanoma, 48% (10/21; 95% CI, 25.7% to 70.2%); SCCHN, 36% (8/22; 95% CI, 17.2% to 59.3%); NSCLC, 33% (7/21; 95% CI, 14.6% to 57.0%); and urothelial cancer 25% (5/20; 95% CI, 8.7% to 49.1%). The most common treatment-related adverse events were fatigue (58%), diarrhea (52%), hypertension (47%), and hypothyroidism (42%). CONCLUSION Lenvatinib plus pembrolizumab demonstrated a manageable safety profile and promising antitumor activity in patients with selected solid tumor types.

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