Real-world outcomes of mosunetuzumab use in relapsed/refractory indolent lymphomas: a CUBIC consortium analysis

Mosunetuzumab (mosun) is a CD20 × CD3 bispecific antibody approved for follicular lymphoma. Despite promising results in clinical trials, there are limited real-world data to assess outcomes with mosun, particularly in patients with poor performance status or significant comorbidities. To address this need, we performed a multicenter retrospective study at 9 centers in the Collaborative US Bispecifics Consortium and identified 119 patients who received mosun for non-Hodgkin lymphoma. Ninety patients (75.6%) had indolent lymphomas, 26% of whom would not have been eligible for the mosun registrational trial. Of these patients, 97% received single-agent mosun. Overall response rate was 87%, and the complete response rate was 71%. With a median follow-up of 17.0 months, median progression-free survival (PFS) and overall survival (OS) were not reached. Eighteen-month PFS and OS estimates were 56.7% and 92.9%, respectively. Most cases of cytokine release syndrome or immune effector cell-associated neurotoxicity syndrome were low grade, with no differences in survival between trial-eligible and trial-ineligible patients. There was a higher rate of infections in trial-ineligible patients than in trial-eligible patients (45% vs 21%; P = .043). These findings support the use of mosun in the treatment of relapsed/refractory indolent lymphomas, even in trial-ineligible patients.