The US Food and Drug Administration has granted orphan drug designation to zavabresib (OPN-2853) for the treatment of myelofibrosis. The generic name of zavabresib for OPN-2853 has also been approved by the International Nonproprietary Names for Pharmaceutical Substances.
The therapy is currently being evaluated in the Phase 1 PROMise study as an add-on to ruxolitinib in patients with myelofibrosis who are no longer responding to ruxolitinib alone.
Data presented at the American Society of Hematology Annual Meeting & Exposition in December 2025 showed that zavabresib was well tolerated and demonstrated a 50% or greater reduction in spleen length in 16 of 26 evaluable patients, according to a press release from Opna Bio, the manufacturer of the therapy.
