Anlotinib versus placebo as adjuvant therapy for completely resected high-grade soft tissue sarcomas: Interim results of a phase 2, double-blinded, randomized controlled trial.

11562 Background: High-grade soft tissue sarcomas (STS) pose a therapeutic challenge due to the high risk of recurrence, even following complete resection. Anlotinib is a multi-targeted tyrosine kinase inhibitor blocking angiogenesis pathways of VEGFR, FGFR, and PDGFR. Given a promising efficacy for treating patients with unresectable advanced STS in previous trials, we evaluated the role of anlotinib as adjuvant therapy for completely resected high-grade STS. Methods: In a single-center, double-blinded, randomized, controlled trial, eligible patients were those adults who had not received adjuvant chemotherapy regimens after complete resection of high-grade STS. Patients were randomly assigned in a 1:1 ratio to receive either oral 12 mg anlotinib or placebo once daily on days 1-14 every 3 weeks as a cycle, with up to six cycles until disease recurrence, unmanageable toxicity or death. The primary endpoints included 1-year, 2-year disease-free survival (DFS). Results: Between June 2019 and November 2023, 88 patients were randomly assigned to receive anlotinib (n=44) or placebo (n=44). With a median follow-up of 25.99 months at data accrual cutoff on Jan 15, 2024, the 1-year and 2-year DFS rates were 88% and 77% in the anlotinib group, compared to 64% and 58% in the placebo group. Compared to patients in the placebo group, patients in the anlotinib group had a reduced risk of disease recurrence (HR 0.47 95% CI 0.22~1.00, P= 0.0445). The median DFS was not reached. Based on tumor histology, the greatest improvement in DFS with anlotinib versus placebo was observed in patients with myxofibrosarcoma (1-year DFS rate: 82% versus 61%; 2-year DFS rate: 64% versus 43%, HR 0.54 95% CI 0.17~1.65, P= 0.2698) and undifferentiated pleomorphic sarcoma (1-year DFS rate: 86% versus 67%; 2-year DFS rate: 78% versus 67%, HR 0.58 95% CI 0.12~2.87, P= 0.4971). Thirty-eight patients experienced adverse events (AEs; 34 with grade 1~2, 4 with grade 3): 28 patients (64%) in the anlotinib group versus 10 patients (23%) in the placebo group ( P<0.001). Three patients discontinued anlotinib, including two for proteinuria/hematuresis (2/44, 5%) and one for secondary poor surgical wound healing (1/44, 2%). Conclusions: Current results suggest anlotinib could lower disease recurrence risk in patients with completely resected high-grade STS, with an acceptable toxicity profile. Clinical trial information: NCT03951571 . Table: see text