Mosunetuzumab-axgb (Lunsumio) is showing promise in the treatment of follicular lymphoma, according to findings presented at the 2024 American Society of Hematology Annual Meeting & Exposition (ASH). While no clear subgroup benefit emerged in the Morningsun trial (NCT05207670) evaluating mosunetuzumab in patients with previously untreated, low-tumor burden follicular lymphoma, the overall response rates are encouraging, and ongoing trials are set to further elucidate its efficacy.
Morningsun Trial Results
The phase 2 Morningsun trial evaluated mosunetuzumab in patients with previously untreated, low-tumor burden follicular lymphoma. Data revealed that among patients with at least one post-baseline tumor assessment (n = 60), the objective response rate (ORR) was 95.0% (95% CI, 86.1%-99.0%), with a complete metabolic response (CMR) rate of 83.3% (95% CI, 71.5%-91.7%). The median time to response was 2.8 months (range, 2.3-8.3). At the data cut-off, 48 patients had ongoing CMRs, and 5 had partial metabolic responses.
Safety Profile
Among patients evaluable for safety (n = 64), the most common adverse event (AE) was injection-site reaction (70.3%). Cytokine release syndrome (CRS) events occurred in 30 (46.9%) patients, with 8 requiring hospitalization for serious AEs. There were 2 instances of suspected immune effector cell-associated neurotoxicity syndrome (ICANs), presenting as confusional states. Infections occurred in 30 (46.9%) patients, with 7.8% experiencing grade 3 infection. A single grade 5 AE occurred 13.7 months after treatment completion, the cause of which was unknown.
Ongoing Research
In addition to the Morningsun trial, other ongoing trials are evaluating mosunetuzumab in patients with follicular lymphoma. A phase 1/2 trial (NCT02500407) is evaluating mosunetuzumab in patients with relapsed or refractory disease. The phase 3 SWOG-2308 trial (NCT06337318) is comparing the safety and efficacy of mosunetuzumab with rituximab in patients with low-tumor burden follicular lymphoma.
According to Dr. John M. Burke, a board-certified hematologist and medical oncologist of the Rocky Mountain Cancer Centers, no notably higher benefit with mosunetuzumab was observed for any specific patient subgroups in the Morningsun trial, other than distinguishing between different lines of therapy. These ongoing trials aim to provide further insights into the potential of mosunetuzumab in treating follicular lymphoma and to identify potential patient subgroups that may benefit most from this therapy.
