Long-term data from Lunsumio's (mosunetuzumab) pivotal phase 1/2 study has demonstrated sustained efficacy in treating relapsed or refractory follicular lymphoma, marking a significant advancement in bispecific antibody therapy. The findings, published in the February issue of Blood, represent the longest follow-up data available for this therapeutic class.
Impressive Long-term Efficacy Data
The study, following 90 patients for a median of 37.4 months, revealed compelling results. Investigators reported a complete response rate of 60% and an objective response rate of 77.8%. Among the 70 responding patients, the median duration of response reached 35.9 months. Notably, 49 of 54 patients achieving complete response maintained their remission status post-treatment.
The Kaplan-Meier estimates showed a 72.4% remission rate at 30 months, while the three-year overall survival rate stood at 82.4%. The median progression-free survival was 24.0 months, with median overall survival not yet reached.
Safety Profile and Treatment Advantages
The fixed-duration regimen of eight cycles demonstrated a manageable safety profile. The median time to CD19+ B-cell recovery post-treatment was 18.4 months. Importantly, no new cytokine release syndrome cases or fatal, serious, or grade 3 or higher adverse events were reported during the extended follow-up period.
Implications for Reimbursement in Korea
As Korea's first drug approved under the Global Innovative Products Fast Track (GIFT) program, Lunsumio stands apart from other bispecific antibodies in the reimbursement landscape. While several bispecific antibody therapies, including Columvi, Epkinly, Tecvayli, and Elrexfio, have faced challenges at the Cancer Disease Review Committee due to limited long-term data, Lunsumio's comprehensive three-year data could set a new precedent.
The therapy offers several distinctive advantages:
- Outpatient administration capability
- Minimal corticosteroid pretreatment requirements
- Fixed-duration treatment of eight cycles
- Demonstrated long-term survival benefits
- Potential cost-effectiveness compared to conventional treatments
Clinical Significance
"Mosunetuzumab fixed-duration administration demonstrates that durable remission can be achieved after three years of follow-up in patients with relapsed-refractory follicular lymphoma who have received multiple prior therapies," the researchers emphasized. This extended analysis provides robust evidence of sustained clinical benefits and reinforces the therapy's manageable safety profile.
As the first CD20-CD3 bispecific antibody approved in Korea, Lunsumio's comprehensive long-term data could potentially pave the way for broader acceptance and reimbursement of bispecific antibody therapies in the region.
