On 29th November 2017, the US Food and Drug Administration (FDA) granted Orphan Drug Designation to AMV564, a novel CD33/CD3 bispecific T-cell engager, for the treatment of patients with Acute Myeloid Leukemia (AML). AMV564, is a novel T-cell engager, derived from protein sequences that binds to both CD3 and CD33.1
CD33, a 67-kDa type I transmembrane receptor, is expressed by cells of myeloid origin but not by normal hematopoietic cells. In AML, CD33 surface antigen is expressed in approximately 90% of leukemic blast cells. Upon administration, AMV564, binds to CD3 expressing T-cells and CD33-positive tumor cells, thereby crosslinking CD33-expressing tumor cells and cytotoxic T-lymphocytes (CTLs). This leads to a potent CTL-mediated cell lysis of CD33-expressing cells. Preclinical studies with AMV564 have demonstrated that this bispecific antibody could induce potent anti-leukemic activity in AML patient samples that was independent of CD33 expression level, disease stage and cytogenetics. 1,2
Currently, AMV564 is being evaluated in a phase I dose-escalation study (NCT03144245), which is assessing the safety, tolerability and preliminary anti-leukemic activity of AMV564 in patients with relapsed or refractory AML. The primary outcomes of the dose-escalation plus expansion stage of the study were the incidence of all Adverse Events (AEs) and serious AEs. The primary outcome of the expansion stage of the study is the rate of remission.