Aptevo Therapeutics Inc. (NASDAQ: APVO) is witnessing a substantial surge in share value during Wednesday’s pre-market session, rising 152.84% to $7.13. The stock’s sharp increase follows the company’s announcement of updated clinical-trial data.
Clinical Breakthrough
Aptevo Therapeutics shared data from its Phase 1b/2 RAINIER trial of mipletamig—a first-in-class CD123 x CD3 bispecific antibody being tested in combination with standard therapies venetoclax and azacitidine (ven/aza) in patients newly diagnosed with acute myeloid leukemia (AML) who are unfit for intensive chemotherapy.
Exceptional Remission Rates in Frontline AML
According to Aptevo, the combination therapy demonstrated remission in 85% of evaluable frontline AML patients across two studies. This rate notably surpasses outcomes seen in comparator trials such as the Viale A study, which evaluated ven/aza alone.
The first two patient cohorts showed encouragingly no signs of cytokine release syndrome (CRS), a common and severe adverse effect in many immunotherapies. Nearing full enrollment is Cohort 3, which is evaluating the greatest dosage level to yet.
Strategic Innovation Behind Mipletamig
The high efficacy and favorable safety data are credited to Aptevo’s proprietary CD3 engineering platform. Mipletamig uniquely utilizes the CRIS-7 binding domain, a strategic design intended to reduce cytokine-driven toxicity while maintaining potent anti-cancer activity.
This engineering approach not only underpins mipletamig’s current success but is also expected to strengthen future candidates in Aptevo’s pipeline, such as its preclinical prostate cancer therapy, APVO442.
Redefining AML Therapy for Unfit Patients
AML is a particularly aggressive blood cancer, with limited options and generally poor outcomes for elderly or medically unfit patients. Aptevo’s findings suggest that mipletamig may offer a new, more effective, and better-tolerated frontline therapy.
With 85% remission achieved—three of which were in patients with high-risk genetic profiles—Aptevo (APVO) positions mipletamig as a promising candidate to redefine treatment paradigms and elevate standards of care in a historically underserved population.
