Phase III SOUNDTRACK-F1 trial: Surovatamig + rituximab in previously untreated FL

Results from the safety run-in portion of the global, randomized, open-label phase III SOUNDTRACK-F1 (NCT06549595) trial, evaluating surovatamig + rituximab vs chemotherapy + rituximab in patients with previously untreated follicular lymphoma (FL) and high tumor burden, were presented by Chan Y. Cheah at the European Hematology Association (EHA) 2026 Congress, June 11–14, 2026, Stockholm, SE. Patients were assigned to receive either 2.4 mg (n = 22) or 7.2 mg (n = 21) surovatamig. The safety run-in primary endpoints were safety and tolerability and the selection of the recommended phase III dose (RP3D).

Key data: All patients experienced at least one treatment-emergent adverse event (TEAE). Serious TEAEs were reported in 36.4% of patients in the 2.4 mg group vs 28.6% in the 7.2 mg group, with 18.2% vs 19.0% considered surovatamig-related, respectively. Grade ≥3 surovatamig-related TEAEs were reported in 40.9% vs 38.1% of patients, and Grade 5 adverse events (AEs) were reported in 4.5% vs 0% of patients. Infections were mostly low grade, with Grade ≥3 infections reported in 9.1% vs 14.3% of patients. Cytokine release syndrome (CRS) was reported in 36% vs 38% of patients and was limited to Grade 1 or 2. Immune effector cell-associated neurotoxicity syndrome (ICANS) occurred in 5% of patients in each group. The overall response rates (ORRs) were 96% vs 100%, with complete responses in 82% vs 95% of patients. Patients receiving 7.2 mg surovatamig demonstrated a 100% measurable residual disease (MRD) negativity rate and a longer duration of response (DoR) vs 2.4 mg, supporting 7.2 mg surovatamig as the RP3D.

Key learning: Surovatamig + rituximab demonstrated deep responses and manageable safety at both dose levels, though 7.2 mg surovatamig achieved greater response rates and attainment of MRD-negativity, supporting further investigation in phase III trials.