ASH 2023 | Updated safety and efficacy results of Abbv-383, a novel BsAb, in patients with R/R multiple myeloma

So, I’m here at the ASH 2023 meeting, and I have a poster here looking at a novel bispecific Abbv-383 in patients with relapsed and refractory multiple myeloma. This is a novel bispecific wherein there are two BCMA binding domains. There is actually a low-affinity CD3 binding domain and also the Fc segment has been modified to give this drug a long half-life. So, it is unique among all the bispecifics to BCMA, of which there are several. The drug has undergone Phase I/II development, and the Phase III trial has just launched. 

The Phase I/II trial has shown robust efficacy. There were multiple dose levels studied, and the initial dose escalation occurred up to 60mg every three weeks. Thereafter, there were backfill cohorts with additional patients being accrued at 20mg every three weeks and 40mg every three weeks, and a cohort was subsequently added on with 60mg every four weeks. The 60mg every four weeks schedule is what we’ll be going forth in Phase III development. But as far as the data goes, what we have is, with the 60mg every three weeks schedule, the longest follow-up, the 60mg every four weeks, has shorter follow-up. The drug has been very well tolerated. With this drug, there is no step-up dosing. Patients are admitted for only 24 hours after the 60mg every four week dose, after having been given some enhanced premedication, including higher doses of dexamethasone. 

The rates of grade two CRS are 5%. There is no grade 3 or 4 CRS noted. The drug is very well tolerated in other aspects as well. The efficacy of the drug is clearly demonstrated in the poster with high rates of complete response and overall response. The median PFS of the 60mg every three week cohort, which has the longest follow-up, is about 11.2 months. It is not reached for the 60mg every four week cohort since that cohort, as I said, was accrued last and has the shortest follow-up. So this is a drug that is certainly unique among the bispecifics on several accounts. As mentioned, the unique structure, the short hospitalization, the low levels of toxicity, and the convenient dosing schedule. So I think that hopefully, this will, in the future, provide patients with a valuable treatment option as in this heavily pretreated cohort of patients, we see very robust activity.