Phase 1b dose escalation to determine the RP2D
DISEASE, INV
Mosunetuzumab was administered intravenously in 21-day cycles with cycle 1 step-up dosing: 1 mg on cycle 1, day 1 (C1D1); 2 mg on C1D8; escalated to a loading dose (9 mg, 20 mg, 40 mg or 60 mg) on C1D15 and C2D1; and then continued at the target dose (9 mg, 20 mg, 40 mg or 30 mg) from C3 onwards. Patients with a complete response completed mosunetuzumab after C8, whereas those with a partial response or stable disease continued mosunetuzumab for a total of 17 cycles. Polatuzumab vedotin was administered intravenously before mosunetuzumab at the standard dose of 1.8 mg/kg on D1 of C1–C6 (see The maximum tolerated dose (MTD) was not reached with any of the mosunetuzumab dosing schedules investigated: 1/2/9 mg (In the phase 1 cohort, per INV assessment, best overall complete response rate based on positron emission tomography-computed tomography (PET-CT) and/or CT scan was 47.4% (9/19; 95% CI: 24.5–71.1), and best ORR was 63.2% (12/19; 95% CI: 38.4–83.7), with median DoR not reached (95% CI, 6.3–NE) based on a median follow-up of 41.5 months.