ASH 2025 | Pirtobrutinib in R/R mantle cell lymphoma: final update from the Phase I/II BRUIN trial

So the BRUIN study was presented quite a few years ago and it was FDA approved. This time we have four to five year data. So basically we’ve had longer data. So the main issue is how does a patient do mainly in terms of toxicity and did we have, with the prolonged treatment, do we have more side effects? 

First of all, the efficacy stayed relatively the same; the prior primary analysis was around 50 and this time is also around 50 percent response rate. And the CRs are also similar. But there’s only mild changes in toxicities. Atrial fibrillation during the four years of 50.9 months of follow-up time, there’s only one more case of atrial fibrillation, which is reversible and was under control. And there was one more patient with ventricular tachycardia that was also reversible. So we do not see more toxicity events accumulate. 

So I really think that pirtobrutinib remained a very good drug with a durable response and should it be continued to be used. So that was the accelerated approval and five-year follow-up data. And so now the phase three study is finishing enrolling. The phase three is basically pirtobrutinib versus any BTK of choice – that’s a randomized trial data. I think that this trial most likely would be positive, especially in the toxicity area as pirtobrutinib, in my opinion, is the least toxic BTK inhibitor we have. So not much new, but a prolonged efficacy, prolonged lack of toxicity.

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