Phase II studies evaluate tislelizumab plus sitravatinib or anlotinib maintenance in extensive-stage small-cell lung cancer.

Two prospective phase II single-arm studies evaluated maintenance therapy in previously untreated extensive-stage small-cell lung cancer (ES-SCLC). Trial 1 administered tislelizumab plus sitravatinib, while Trial 2 used tislelizumab plus anlotinib. Both regimens followed induction therapy with tislelizumab and platinum-based chemotherapy for four cycles. Each trial enrolled 21 patients, with 18 entering the maintenance phase for analysis.

The primary endpoint was the 1-year progression-free survival (PFS) rate in the maintenance analysis set. Secondary endpoints included median PFS and overall survival (OS) from both maintenance and induction starts, plus treatment-related adverse events. In Trial 1, median PFS from maintenance initiation was 6.4 months, with a 1-year PFS rate of 22.2%. Median OS from maintenance was 18.3 months. In Trial 2, median PFS from maintenance was 7.8 months, and the 1-year PFS rate was not reached. Median OS from maintenance was not reached.

Safety profiles were generally favorable. The most common grade ≥3 treatment-related adverse events were hypertension (22.2%) in Trial 1 and fatigue (5.6%) in Trial 2. No patients died from treatment-related adverse events in either study. However, serious adverse events and discontinuation rates were not reported. Median PFS from induction therapy was 9.1 months (Trial 1) and 10.8 months (Trial 2).

Key limitations include the single-arm design, small sample size of 18 patients per trial in the maintenance phase, and lack of reported statistical comparisons. As these are single-arm studies, causality cannot be established, and generalizability remains uncertain. The practice relevance is currently limited, warranting further exploration in larger-scale randomized trials before clinical adoption.