Aptevo Therapeutics Inc. reported that all patients in Cohorts 1‑3 of its Phase 1b/2 RAINIER study—combining azacitidine and venetoclax with the bispecific antibody mipletamig—remained free of cytokine release syndrome (CRS), a common safety concern for T‑cell engagers. The interim analysis also showed an 85 % overall remission rate in frontline acute myeloid leukemia (AML) patients who are unfit for intensive chemotherapy, a figure that aligns with the company’s earlier cohort data and underscores the drug’s therapeutic potential.
The 100 % CRS‑free outcome is a direct result of Aptevo’s proprietary CRIS‑7‑derived CD3 binding domain, which is engineered to limit excessive immune activation while preserving T‑cell engagement. The trial population had a median age of 75 years, reflecting the real‑world cohort that is most in need of tolerable, effective therapies. Mipletamig also carries orphan drug designation for AML, positioning it for potential market exclusivity upon approval and providing a strategic advantage in a crowded therapeutic landscape.
Chief Medical Officer Dirk Huebner said the data “demonstrate the safety and efficacy of mipletamig as part of a frontline AML regimen,” while President and CEO Marvin White highlighted that the results “reinforce our conviction that mipletamig is a differentiated medicine that can be integrated with the venetoclax and azacitidine backbone to elevate outcomes for patients who have had too few options.”
The high remission rate combined with the absence of CRS is expected to be a key driver of investor interest and could accelerate regulatory discussions. The findings also support Aptevo’s broader pipeline strategy, which includes expanding the CRIS‑7 platform into trispecific candidates and other solid‑tumor indications. The data reinforce the company’s positioning as a leader in next‑generation bispecific antibody development and may enhance its attractiveness for future partnerships or funding opportunities.
The content on BeyondSPX is for informational purposes only and should not be construed as financial or investment advice. We are not financial advisors. Consult with a qualified professional before making any investment decisions. Any actions you take based on information from this site are solely at your own risk.