Aptevo announces complete remission in second patient in APVO436 trial cohort

Aptevo Therapeutics provided an update on its ongoing APVO436 Phase 1 clinical trial. APVO436 is a novel anti-CD123 x anti-CD3 targeted investigational bispecific antibody therapy being evaluated for the treatment of acute myeloid leukemia, or AML, and myelodysplastic syndrome, or MDS, in a Phase 1/1b open-label, dose-escalation study evaluating the safety and pharmacokinetic profile. Aptevo received preliminary data regarding cohort 6, which indicated complete remission in a second patient, in addition to the one previously announced. In total, there are now two patients with clinical remission in cohort 6. The data received also showed one patient exhibiting stable disease status, and six patients where the disease had progressed. A total of nine patients were listed in cohort 6 of the clinical trial. Patient bone marrow blasts were 33% at screen, exhibited a rise in blasts to 46% after the first cycle of treatment. Subsequently, the bone marrow blasts dropped to 8% after the second cycle, and to 4% after the fourth cycle of treatment. The patient's platelet count and absolute neutrophil count met complete remission criteria. "It is very encouraging that two complete remissions have been observed in Cohort 6, as we are now enrolling in cohort 8," said Marvin White, President and CEO of Aptevo Therapeutics. "We are now in a critical phase of the study, as pharmacokinetic modelling suggests that dosing in cohorts 5 through 8 is in a therapeutic range, which could result in potential clinical activity of the drug. We look forward to continuing the dose escalation and monitoring potential clinical responses as we advance through the upcoming dose cohorts," concluded White.