Safety and efficacy of mosunetuzumab, a bispecific antibody, in patients with relapsed or refractory follicular lymphoma: a single-arm, multicentre, phase 2 study
A newer report of this study has been published: Long-term 3-year follow-up of mosunetuzumab in relapsed or refractory follicular lymphoma after ≥2 prior therapies. (2025)
- Study type
- Clinical trial
- Phase
- Phase 2
- Design
- Single-arm, multicentre study
- Sample size
- 90 patients
- Source
- The Lancet Oncology · 2022
- Trial registration
- NCT02500407
In plain words
Mosunetuzumab is a drug that steers the body's immune cells (T cells) towards cancerous lymphoma cells so that they destroy them. In this study, the drug was given for a set length of time to patients with follicular lymphoma whose disease had come back or had not responded after two or more earlier treatments. About 60% of patients had a complete remission. The most common side effect was cytokine release syndrome (fever and inflammation-like symptoms), which was mostly mild to moderate and happened at the start of treatment.
Key results
Treatment arms and regimens
Mosunetuzumab IV in 21-day cycles with step-up dosing in cycle 1: 1 mg on day 1 of cycle 1, 2 mg on day 8 of cycle 1, 60 mg on day 15 of cycle 1 and day 1 of cycle 2, and 30 mg on day 1 of cycle 3 and subsequent cycles. Patients with a complete response (investigator-assessed by International Harmonisation Project criteria) completed treatment after cycle 8, while patients with a partial response or stable disease continued treatment for up to 17 cycles.
Source of the regimen details: Abstract of the paper
Doses are given for the information of specialists, as in this study’s protocol, and are not a prescription. Every drug must be prescribed by the treating physician for the individual patient.
Study population
Patients aged 18 years and older with histologically confirmed follicular lymphoma (grade 1 to 3a) and an ECOG performance status of 0 to 1. Disease had to be relapsed or refractory to two or more prior lines of therapy, including an anti-CD20 therapy and an alkylating agent. The study was conducted at 49 centres in seven countries (Australia, Canada, Germany, South Korea, Spain, the UK and the USA).
Endpoints
Primary endpoint: complete response rate (as best response) assessed by an independent review committee (IRC) in all enrolled patients; in the primary efficacy analysis, the observed complete response rate was compared with a 14% complete response rate in a historical control (similar patients treated with copanlisib, a pan-class I PI3K inhibitor). Safety was assessed in all enrolled patients.
Safety and side effects
The most common adverse event was cytokine release syndrome (40 of 90 patients, 44%), mainly grade 1 (23 patients, 26%) and grade 2 (15 patients, 17%), occurring mostly in cycle 1. The most common grade 3–4 adverse events were neutropenia or decreased neutrophil count (24 patients, 27%), hypophosphataemia (15 patients, 17%), hyperglycaemia (7 patients, 8%) and anaemia (7 patients, 8%). Serious adverse events occurred in 42 patients (47%). There were no treatment-related grade 5 (fatal) adverse events.
Clinical significance and place in guidelines
This phase 2 study showed that fixed-duration mosunetuzumab in follicular lymphoma relapsed or refractory after two or more prior therapies achieves a high complete remission rate with a favourable safety profile and can be given in the outpatient setting. The comparison was with a historical control, not a concurrent control group; the drug's approval status and its place in treatment guidelines should be checked separately.
Limitations
The study was single-arm, and the primary comparison was with a historical control (copanlisib in a similar population), not a concurrent randomised control group. The study is ongoing and median follow-up was 18.3 months.
This summary was prepared by the editorial team from the published paper; the original paper is the final reference. Read the original abstract on PubMed.