Xencor, Inc. announced that the U.S. Food and Drug Administration (FDA) has placed a partial clinical hold on its Phase 1 study of XmAb14045, a CD123 x CD3 bispecific antibody molecule being evaluated in patients with relapsed or refractory acute myeloid leukemia and other CD123-expressing hematologic malignancies. Patients currently on treatment and benefiting from treatment may continue treatment on the study. No new patients will be allowed to enroll in the study until the partial clinical hold is lifted by the FDA.
The partial clinical hold was initiated following recent safety reports Xencor submitted to the FDA on two patient deaths that were considered at least possibly related to XmAb14045. One patient experienced cytokine release syndrome (CRS) after their first dose, the treatment of which was complicated by the patient’s decision to withdraw care. One patient developed acute pulmonary edema following several doses of XmAb14045. The FDA has placed the trial on partial clinical hold pending review of additional details regarding these events, safety and efficacy information across the study, and satisfactory review of amendments to the study protocol and related documents. Xencor will be working closely with the FDA to review these events and resolve the partial clinical hold.
“Patient safety is Xencor’s highest concern,” said Bassil Dahiyat, Ph.D., president and chief executive officer at Xencor. “We are working with the investigators and the FDA and will provide an update when more information about resuming enrollment can be shared. Our ongoing Phase 1 studies evaluating our other CD3 bispecific antibodies, XmAb13676 and XmAb18087, are not affected.”