KEY TAKEAWAYS
- The phase II study assessed mosunetuzumab in patients with R/R FL.
- The study’s primary endpoint was CR.
- The study showed that mosunetuzumab maintained effectiveness and had a consistent, low-risk safety profile suitable for outpatient care.
This phase II study aimed to assess mosunetuzumab in patients (pts) with relapsed/refractory (R/R) follicular lymphoma (FL) after a 28.3-month median follow-up. The primary outcome measured was the rate of complete response (CR). Subsequent analyses evaluated the effectiveness of mosunetuzumab against the most recent prior treatment and examined the relationship between cytokine release syndrome (CRS) and tumor response.
The study included 90 pts with a median age of 60, ranging from 29 to 90 years old. The majority of pts, 77%, were diagnosed with stage III/IV of the disease, and the median number of treatments previously undergone was 3, with a range from 2 to 10. As of July 8, 2022, the initial study treatment was completed by 62% of the participants. Investigator-assessed objective response rate (ORR) and complete response (CR) rate with mosunetuzumab were 78% and 60%, respectively. These rates compare favorably to 56% ORR and 36% CR with the last prior treatment. Additionally, the median progression-free survival (PFS) was 24 months with mosunetuzumab, as opposed to 12 months with the last therapy. The 24-month PFS rate was 48% when treated with mosunetuzumab.
Mosunetuzumab improved the last treatment in several areas: median duration of response (not reached [NR] vs. 12 months), median duration of complete response (NR vs. 15 months), and time to next therapy or death (NR vs. 17 months). Regarding side effects, 44% of pts experienced CRS events, but these were primarily (95% of cases) Grade 1/2 in severity. No new CRS events or any fatal, serious, or Grade ≥3 adverse events have been noted since the last analysis. Finally, the ORR was consistent among pts, regardless of whether they experienced CRS events.
Mosunetuzumab showed durable responses in the study. Its safety profile, mainly featuring low-grade CRS events, supported outpatient administration and was in line with prior studies. CRS occurrence did not affect the treatment’s clinical response.
Source: https://clml-soho2023.elsevierdigitaledition.com/452/index.html
Clinical Trial: https://classic.clinicaltrials.gov/ct2/show/NCT02500407
Bartlett, N.L., Sehn, L.H., Matasar, M., Schuster, S.J., Assouline, S., Giri, P., Kuruvilla, J., Canales, M., Dietrich, S., Fay, K., Ku, M., Nastoupil, L., Wei, M.C., Yin, S., To, I., Huang, H., Min, J., Bolen, C.R., Penuel, E., Budde, L.E. Mosunetuzumab Monotherapy Demonstrates Durable Efficacy With a Manageable Safety Profile in Patients With Relapsed/Refractory Follicular Lymphoma who Received ≥2 Prior Therapies: Updated Results From a Pivotal Phase II Study.
