Anlotinib plus TQB2450, a PD-L1 Antibody, in Patients with Advanced Alveolar Soft Part Sarcoma: a single-arm, phase 2 trial

Purpose: Alveolar soft part sarcoma (ASPS) is an ultra-rare 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 ASPS patients. Methods: This single-arm, phase 2 study evaluated the efficacy of TQB2450, an anti-programmed death ligand 1 (PD-L1) agent, combined with anlotinib, a TKI, 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 day 14 every 3 weeks. The primary endpoint was overall response rate, with secondary endpoints including duration of response (DOR), progression-free survival (PFS), and overall survival (OS). Lymphocyte infiltration and tertiary lymphoid structure (TLS) were also analyzed as potential prognostic biomarkers. Results: The study enrolled 29 patients, with 28 evaluable (one withdrew due to 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 DOR was not reached, with an estimated median PFS of 35.2 months. Grade 3-4 treatment-related adverse events occurred in 44.8% of patients, with no study-related deaths. Responders had a higher proportion of TLS area, density, and CD20-positive immune cells. Conclusions: The combination of anlotinib and TQB2450 is effective and tolerable in ASPS patients. TLS may serve as a prognostic biomarker, meriting further investigation.