Anlotinib plus TQB2450, a PD-L1 Antibody, in Patients with Advanced Alveolar Soft Part Sarcoma: A Single-Arm, Phase II Trial.

Purpose: Alveolar soft part sarcoma (ASPS) is an ultrarare soft-tissue sarcoma with a high rate of metastasis and no established treatment. This study aimed to explore the efficacy and safety of anlotinib (a tyrosine kinase inhibitor) and TQB2450 (a PD-L1 inhibitor) in patients with ASPS.

Patients And Methods: This single-arm, phase II study evaluated the efficacy of TQB2450, an anti-PD-L1 agent, combined with anlotinib, a tyrosine kinase inhibitor, in adults with advanced ASPS. TQB2450 was given intravenously (1,200 mg) on day 1, and anlotinib (12 mg/day) was taken orally from day 1 to 14 every 3 weeks. The primary endpoint was overall response rate, with secondary endpoints including duration of response, progression-free survival, and overall survival. Lymphocyte infiltration and tertiary lymphoid structure (TLS) were also analyzed as potential prognostic biomarkers.

Results: The study enrolled 29 patients, of whom 28 were evaluable (one withdrew because of acute pancreatitis). An objective response was achieved in 82.1% of patients, including 4 complete and 19 partial responses. The median time to response was 2.8 months, and the duration of response was not reached, with an estimated median progression-free survival of 35.2 months. Grade 3 to 4 treatment-related adverse events occurred in 44.8% of patients, with no study-related deaths. Responders had a higher proportion of TLS area, TLS density, and CD20-positive immune cells.

Conclusions: The combination of anlotinib and TQB2450 is effective and tolerable in patients with ASPS. TLS may serve as a prognostic biomarker, meriting further investigation.