Chugai Pharmaceutical Co., Ltd. has announced that the Ministry of Health, Labour and Welfare (MHLW) in Japan has granted regulatory approval for Lunsumio (mosunetuzumab) for intravenous infusion. This approval covers the treatment of patients with relapsed or refractory (R/R) follicular lymphoma (FL) who have received two or more prior standard therapies. Lunsumio, a CD20/CD3 bispecific antibody, offers a new therapeutic option with the potential for durable remission in this patient population.
Clinical Efficacy and Safety
The approval is based on data from the FLMOON-1 study, a Japanese Phase I study with an expansion cohort, and an overseas Phase I/II clinical trial conducted by Roche. Both studies evaluated the efficacy and safety of Lunsumio as a monotherapy in patients with R/R FL who had received two or more prior standard therapies.
In the FLMOON-1 study, conducted with 19 Japanese patients, the complete response rate (CRR), as assessed by an independent review facility (IRF), was 68.4% (90% confidence interval: 47.0-85.3%). The most frequent adverse reactions included lymphocyte count decrease, cytokine release syndrome, alanine aminotransferase increase, neutrophil count decrease, aspartate aminotransferase increase, and infusion-related reactions.
The overseas Phase I/II study included 90 patients with R/R FL who had previously received two or more standard therapies. The primary endpoint, CRR as assessed by an IRF, was 57.8% (95% confidence interval: 46.9-68.1%). The most frequent adverse reactions were cytokine release syndrome, fever, fatigue, pruritus, neutropenia, and hypophosphatemia.
Mechanism of Action
Lunsumio is a CD20/CD3 T cell-engaging bispecific antibody designed to target CD20 on B cells and CD3 on T cells. This mechanism is expected to activate the immune system through cytotoxic T cells, leading to antitumor effects on CD20-expressing tumor cells. Lunsumio has already been approved in 61 countries worldwide and is being developed with both intravenous and subcutaneous formulations for the treatment of R/R FL and R/R aggressive B-cell non-Hodgkin lymphoma.
Addressing Unmet Needs in Follicular Lymphoma
Follicular lymphoma is a type of lymphoma that arises when B lymphocytes become cancerous. At diagnosis, a significant proportion of patients (70-85%) are in an advanced stage. While initial chemotherapy is often effective, recurrences are common, making it difficult for existing treatments to remain effective over time. Dr. Osamu Okuda, Chugai’s President and CEO, stated that Lunsumio is expected to provide durable remission with monotherapy and a predetermined treatment duration based on individual patient response, which can help reduce the burden of treatment. In Japan, approximately 9,000 people are reportedly diagnosed with FL each year, highlighting the need for new and effective treatment options.
