Aptevo Therapeutics Inc. announced on October 26, 2026, that ten patients with newly diagnosed acute myeloid leukemia (AML) have proceeded to allogeneic stem cell transplant following treatment with the company's candidate mipletamig in combination with venetoclax and azacitidine.
The company reported that ten of 47 evaluable frontline patients treated with the mipletamig triplet advanced to the transplant procedure. This represents a 21% transplant rate. The patients included nine from the ongoing Phase 1b RAINIER trial and one from a previously completed dose expansion trial.
The company noted that this transplant rate is significantly higher than historical benchmarks for the standard-of-care combination of venetoclax and azacitidine alone. In the pivotal Phase 3 VIALE-A trial, three of 286 patients (0.7%) treated with venetoclax and azacitidine subsequently underwent stem cell transplantation.
The transplant rate is particularly relevant for a patient population initially deemed unfit for intensive induction chemotherapy due to age or underlying health conditions. Aptevo stated that the ability of these patients to proceed to transplant indicates clinical activity of the mipletamig combination.
The company also provided an update on its clinical development timeline. Aptevo expects the RAINIER dose optimization trial to conclude by the end of 2026. The company anticipates discussing next steps with regulators in the first half of 2027 and initiating a Phase 2 clinical trial during that period.
