A multicenter, single-arm, phase 2 study of surufatinib plus toripalimab for patients with advanced endometrial cancer.

Abstract

5609 Background: Several immunotherapy monotherapies, or combined with antiangiogenic inhibitors, have shown antitumor efficacy in endometrial cancer (EMC) and been approved by FDA. However, therapeutic options for EMC after failure of first-line treatment remain scarce in China. The open-label, multi-cohort, single-arm phase 2 study was performed to evaluate the efficacy and safety of the combination of surufatinib (a small-molecule inhibitor of VEGFR 1-3, FGFR1 and CSF-1R) with toripalimab (an anti-PD-1 antibody) for Chinese patients (pts) with EMC after failure of one or more prior lines of systemic treatment. Methods: Pts with EMC who progressed or were intolerable after at least one prior line of systemic antitumor therapy were eligible and enrolled. They received 21-day cycles of surufatinib 250 mg orally, QD, plus toripalimab 240 mg IV, Q3W, until disease progression or reaching the maximum treatment duration with toripalimab of 24 months, or other protocol-specified criteria. The primary endpoint was objective response rate (ORR) per RECIST 1.1. Results: From August 2020 to March 2022, 28 pts were enrolled and received the combination treatment (median duration: 4.6 months). Median age was 58 years (range: 50-71), and 22 (78.6%) pts were endometrioid adenocarcinoma at diagnosis. 9 (32.1%) pts had received ≥2 prior lines of therapy. As of 28 Dec 2022, the median follow-up duration was 16.8 months. Microsatellite status was available in 25 pts. 20 with mismatch repair-proficient (pMMR) and 5 with mismatch repair-deficient (dMMR) were determined. All 28 pts were evaluable with at least one post-baseline tumor assessment. Efficacy results were: confirmed ORR, 28.6% (8 partial response [PRs]); DCR, 82.1%; mDoR, 5.7 months; mPFS (95%CI), 5.4 months (2.7, 8.3); 12-month OS rate, 71.0%. Among pts with pMMR, the confirmed ORR was 25.0%; DCR was 85.0%; mDoR was 4.2 months; mPFS (95%CI) was 4.0 months (2.7, 8.3); 12-month OS rate was 75.4%. All pts experienced at least one treatment-emergent adverse event (TEAE), and 19 (67.9%) of them reported grade ≥3 TEAEs. The most common (≥5% pts) grade ≥3 TEAEs were hypertension (28.6%), aspartate aminotransferase increased (14.3%), alanine aminotransferase increased (10.7%), proteinuria (7.1%), Gamma-glutamyltransferase increased (7.1%) and malignant neoplasm progression (7.1%). No new safety signals were observed. Conclusions: Surufatinib plus toripalimab had a promising antitumor activity and a manageable safety profile in pts with EMC after failure of one or more prior lines of systemic therapy. Clinical trial information: NCT04169672 .