Aptevo Therapeutics Inc. (NASDAQ:APVO) announced that its lead candidate mipletamig achieved a 93% clinical benefit rate when administered as a triplet therapy to frontline acute myeloid leukemia patients carrying TP53 mutations.
The clinical-stage biotechnology firm develops multispecific immuno-oncology therapeutics to target high-risk patient groups that have historically demonstrated poor responses to existing medical treatments.
Strong Remission Outcomes In High-Risk AML
In the evaluation, 13 out of 14 evaluable TP53-mutated subjects receiving mipletamig alongside venetoclax and azacitidine experienced clinical benefit, incorporating two participants from a prior dose-expansion trial.
Overall, 11 patients—representing 79% of the cohort—achieved complete remission or complete remission with incomplete hematologic recovery, with nine of those individuals reaching full complete remission.
The 79% response rate observed with the mipletamig triplet compares favorably to a published 41% composite remission rate for the venetoclax and azacitidine combination alone in treatment-naïve, poor-risk cytogenetic patients.
RAINIER Trial Roadmap And Unique Mechanism
Aptevo is currently conducting the RAINIER study, an open-label, multicenter Phase 1b/2 dose-optimization trial examining adults newly diagnosed with acute myeloid leukemia who cannot undergo high-intensity induction chemotherapy.
Management expects to complete the dose optimization portion across sequential 28-day treatment cycles by year-end, with regulatory meetings planned for the first half of 2027 to set future milestones.
The wholly owned lead candidate redirects a patient’s immune system by binding T cells to CD123-expressing leukemic cells and stem cells to promote cancer destruction.
Additionally, mipletamig employs a CRIS-7-derived CD3-binding pathway specifically designed to minimize the likelihood and severity of cytokine release syndrome, distinguishing the candidate from competing therapeutic options.
APVO Stock Price Activity: Aptevo Therapeutics shares were down 22% to $2.02 at the time of publication on Thursday, according to Benzinga Pro data.
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