Roche announced on September 17, 2026, that the phase III CELESTIMO study evaluating mosunetuzumab (Lunsumio) in combination with lenalidomide met its primary endpoint in people with relapsed or refractory follicular lymphoma (FL) who had received at least one prior line of treatment. The comparator arm was rituximab (MabThera/Rituxan) plus lenalidomide.
At the interim analysis, the combination demonstrated a statistically significant and clinically meaningful improvement in progression-free survival (PFS) versus rituximab plus lenalidomide. Overall survival data were immature at the time of the interim analysis, and specific numerical efficacy figures were not disclosed in the topline announcement. Roche stated that full data will be submitted to health authorities and presented at an upcoming medical meeting.
Key finding
In the phase III CELESTIMO interim analysis, mosunetuzumab plus lenalidomide produced a statistically significant and clinically meaningful improvement in progression-free survival over rituximab plus lenalidomide in relapsed or refractory follicular lymphoma, though specific PFS figures and overall survival data were not reported.
Study Design
| Trial | CELESTIMO (NCT04712097); phase III |
|---|---|
| Population | Adults with relapsed or refractory follicular lymphoma who had received at least one prior line of systemic therapy |
| Treatment | Mosunetuzumab plus lenalidomide vs. rituximab plus lenalidomide |
| Primary endpoint | Progression-free survival |
CELESTIMO is a confirmatory study required to convert the accelerated approval and conditional marketing authorisation of mosunetuzumab monotherapy for third-line or later FL into full approval, and to support a new indication in second-line or later FL. Key secondary endpoints were not specified in the topline announcement.
Results and Safety
The study met its primary endpoint at the interim analysis, with mosunetuzumab plus lenalidomide demonstrating a statistically significant and clinically meaningful reduction in the risk of disease progression compared with rituximab plus lenalidomide. Quantitative PFS data, including hazard ratios and median PFS values, were not disclosed in the topline release.
Overall survival data were described as immature at the time of the interim analysis and were therefore not reported. Roche noted that the safety profile of the mosunetuzumab and lenalidomide combination was consistent with the known profiles of each individual agent, and that no new safety signals were identified.
Clinical Context
Follicular lymphoma is the most common indolent form of non-Hodgkin lymphoma, accounting for approximately one in five cases, with an estimated 110,000 new diagnoses worldwide each year. While the disease typically responds to initial therapy, it is characterized by repeated cycles of remission and relapse, and early progression is associated with a poor long-term prognosis. A positive PFS result in the second-line or later setting is therefore clinically relevant, as treatment options that delay progression earlier in the disease course could meaningfully affect outcomes for a broad patient population.
If the CELESTIMO data support regulatory conversion and label expansion, mosunetuzumab could become available to FL patients earlier in their treatment course than its current third-line or later indication permits. Roche noted that the broader mosunetuzumab program includes the ongoing phase III MorningLyte study in first-line FL, and a separate supplemental BLA for mosunetuzumab in combination with polatuzumab vedotin for second-line or later diffuse large B-cell lymphoma has been accepted by the FDA. Whether the CELESTIMO PFS benefit translates into an overall survival advantage remains to be determined as follow-up matures.
Sources
- Roche. “Roche’s Lunsumio-based regimen significantly improves progression-free survival in follicular lymphoma in phase III CELESTIMO study.” Press release. 17 September 2026. View source.
AI disclosure: This article was prepared with assistance from generative AI using the source material cited above. It was reviewed and edited by Brandon Twyford before publication.