EHA 2025 | Long-term data on obe-cel and its potential as a definitive treatment for adult R/R B-ALL

So, you know, at the EHA meeting in 2025 in Milan, we were able to present a long-term follow-up study now as part of the FELIX study, which was the pivotal study that led to the approval of the product in the United States by the FDA in November 2024. It was in adult patients with relapsed/refractory B-cell ALL. Now, updated data has nearly three years of follow-up, so an additional one-year follow-up since the last data cut, and then the publication that went out last year. And very encouragingly, what the data showed is that 38.4% of the patients were able to maintain NCR in ongoing remission without subsequent stem cell transplant. And since the last data cut, which was again about a year ago, there were no patients who relapsed on study. So that is pretty, you know, very encouraging and exciting result showing that there is a potential for this subset of patients. And nearly 40% of the patients were able to maintain this remission, you know, now reaching almost three years for the total duration of follow-up. So that is an encouraging result for obe-cel. And that data does suggest that, you know, which is the key critical question in the field is that can this CAR T-cell therapy serve as a definitive treatment? And I do think so. Again, I think it has proven to be the case in this subset of the patients. Obviously, we do need longer-term follow-up data beyond three years to ensure that these plateaus of the curve maintain. But the fact that we haven’t seen any relapses beyond two and three years mark, I think it’s very encouraging that hopefully we’ll see a few such events happening beyond three years, too. So it’s a very, very encouraging result that we were able to kind of share the data with the community. In terms of some of the predictive biomarker clinical characteristics, we also looked at it kind of more in the context of who are these patients able to maintain these durable remissions that’s associated with higher event-free survival and overall survival. And there are several factors that we presented, and I encourage you guys to look at the presentations, or at least with the abstract, there aren’t many. But one thing that stood out for the overall survival and event-free survival was the patients who have a lower disease burden at the time of T-cell infusion, which for the B-cell that we do perform a bone marrow biopsy prior to T-cell infusion to determine the dosing strategies. But having a lower burden patients does tend to have a longer durable remission. And the patients who have ongoing CAR T-cell persistence, which we looked at as a time-dependent covariate, that was another associated factor for a better long-term survival. So, you know, I think these are the characteristics that we have found. The one interesting is a prior inotuzumab was came out to be associated with the worst overall survival. However, it is unclear, we’re trying to figure out and we need more data to see it’s not just ino-exposed patients. It’s, you know, they could be very well be ino-refractory patients. We don’t have such data yet to, and there are differences whether you had a response to inotuzumab prior and then relapse afterwards many years later versus you will refract to therapy. The outcome of such patients might differ but we don’t have the data yet so we will need that. But just to clarify the ino prior-exposed patients do not refer to ino bridging. We still do use in those patients after TISA collection that we have used in ino bridging in a separate abstract. Last year we presented those have not impacted the outcome. So the ino-exposed was really meaning to prior to leukophoresis, prior to study entry. So just to clarify. So these are some of the characteristics that we have found to be better predictive markers for the survival. We still do need more data though, because while this data is encouraging that in an ongoing CAR T-cell persistence, we still don’t know what is optimal duration of a CAR T-cell persistence. We know if you see them persisting, it is a good sign. But, you know, usually at a month one and month three mark, when we are left to make the decision as to should I send these patients to transplant or not, that doesn’t provide a total clarity. Kind of in this case, we know who are likely going to do better, who might not. And it doesn’t mean the transplant will be able to overcome these kind of the worst prognostic indicators if they were to. So more data and more work hopefully needs to be done to kind of shed clearer light on that question.

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