EBMT 2026 | Analyzing the incidence of SPMs following T-cell-engaging bispecific antibody therapy

Today it’s my pleasure to talk about second primary malignancy after T-cell engaging bispecific antibodies. And in this study we are exploring the frequency of so-called SPMs after bispecific antibodies and we found out that the estimate is 3.5% which is a little bit lower than a recently published study about CAR T-cells, but given that SPMs are some kind of a hot topic the indications for this therapy I mean bispecific antibody therapy, are very similar to CAR-T. Actually, some people use them interchangeably. We wanted to explore what the true frequency is, but what’s important, we found that the reporting is a little bit biased because different studies show different definitions of SPM outcomes. So some of them report total frequency some of them report only SPMs leading to a treatment discontinuation or death so basically 3.5% is for total SPM reporting and categories regarding death or discontinuation show like 2%, which is not surprising because if somebody limits the report to various more specific outcome it’s going to be lower. 

What’s interesting is that the biological background for SPMs after bispecifics is not really straightforward. We presume that maybe it stems from previous exposure, I mean exposure to previous therapies, because these patients are usually in bad conditions after failing multiple lines, so this may be the cause. But some authors suggest that some immune impairment associated with energy of lymphocytes may play a role. So it’s something to explore in more experimental studies. 

Well, the main finding is that within one or two years after bispecific infusion, we can expect a little bit of risk regarding malignancies. Whether it’s high or no, it’s hard to determine because of insufficient reporting. So our message is that the surveillance should be more detailed to quantify the actual number, because we also found out that patients previously exposed to CAR T-cells had higher percentage of SPMs compared to patients who did not have this exposure and, so we need data to stratify the risk and actually to provide time specific risk because for now our finding is really follow-up dependent. And to tell exactly what the risk is, we would need more specific data. But for now, we know that it exists. It’s low, but still some patients may face additional challenges. And basically we are happy that we managed to even capture this data. So actually I’m from Warsaw from Poland but this work is done under supervision of Dr. Shouval from MSK and New York and Kai Rejeskiski from Munich and I must acknowledge Dr. Tobias Tixs who is the co-first author of this study and we are doing together all this stuff so the team is the teamwork is actually great so now we are preparing revisions for the manuscript and yeah. So the message is 3.5 for now, reporting is selective, and we need better surveillance regarding SPMs after bispecifics.

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