19 SEP 2026 — Roche says its Phase III lymphoma trial met its primary endpoint. It did not publish the hazard ratio, the confidence interval, the median survival figures or how many patients took part.
The company published that the improvement was statistically significant and clinically meaningful, that no new safety signals appeared, and that overall survival data were immature at the interim analysis.
What CELESTIMO tested
The trial compared Lunsumio, Roche's mosunetuzumab, combined with lenalidomide against rituximab combined with lenalidomide. The patients had relapsed or refractory follicular lymphoma and had already had at least one prior line of treatment.
Mosunetuzumab is a CD20xCD3 bispecific antibody. It binds CD20 on the surface of a malignant B cell and CD3 on a T cell at the same time, physically bringing the two together so the patient's own T cells attack the cancer. Rituximab, the comparator's backbone, targets CD20 alone and has been the standard component of these regimens for over two decades.
So the trial asks a clean question: in the same combination, does engaging T cells directly beat the established antibody? Roche's announcement of 17 September says it does, on progression-free survival.
What a confirmatory trial is for
This is not an ordinary readout. Mosunetuzumab already holds accelerated approval from the FDA and conditional marketing authorisation in the EU for third-line-or-later follicular lymphoma, and both were granted on earlier, less definitive evidence.
CELESTIMO is the trial required to convert those conditional clearances into full approval, and to support a broader indication covering second-line-or-later disease. A drug already reaching patients has now produced the evidence that was promised when it was let through early.
That is the system working as designed. Confirmatory trials sometimes fail, and drugs are sometimes withdrawn when they do. This one did not fail.
What the missing numbers would tell you
"Statistically significant and clinically meaningful" is a claim about a result, not the result. A hazard ratio would say how much the risk of progression fell. A confidence interval would say how precisely that was measured. Median progression-free survival in each arm would say how much additional time without progression a patient might expect.
None of those is available, so the size of the benefit is unknown. A trial can clear statistical significance with a difference that matters greatly to patients or one that matters little. The press release does not distinguish between them.
Immature overall survival is the ordinary state of an interim analysis, not a red flag. But it is the endpoint that answers whether patients live longer, and it remains unanswered.
Why follicular lymphoma is treated in lines
Follicular lymphoma is usually slow-growing and, in most patients, not curable. Treatment proceeds in lines: a regimen works, the disease eventually returns, and the next regimen begins. Moving an effective drug earlier in that sequence changes how much of a patient's life is spent on which therapy.
That is what the second-line indication is about. An outpatient two-drug regimen offered earlier is a different proposition from one reserved until two previous approaches have failed.
Levi Garraway, Roche's chief medical officer, put the claim in those terms, saying the results indicate the regimen "may offer these patients an effective new option earlier in their treatment journey." The word doing the work in that sentence is "may".
What happens next
The data go to health authorities and to an unnamed upcoming medical meeting. That presentation is when the hazard ratio and the curves become public and the size of the effect can be judged.
Until the data are presented, the summary is that a confirmatory trial succeeded on its primary endpoint by an undisclosed amount. Both halves of that sentence matter.
For a second-line indication, safety will matter as much as efficacy. The release reports no new signals. That is meaningful for a T-cell engager, whose known class profile includes cytokine release syndrome — a manageable immune reaction, and the reason these drugs are given with careful monitoring.
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