Opna Bio Granted Orphan Drug Designation for OPN-2853 (Zavabresib) in Myelofibrosis
Thursday, January 22, 2026
Opna Bio has announced that its investigational therapy OPN-2853, also known as zavabresib, has received Orphan Drug Designation from the US Food and Drug Administration for the treatment of myelofibrosis.
OPN-2853 is a small-molecule inhibitor targeting bromodomain and extra-terminal (BET) proteins and is being developed as a potential treatment for blood cancers.
Myelofibrosis is a rare and serious condition marked by scarring of the bone marrow, which disrupts normal blood cell production. Patients commonly experience symptoms such as fatigue, anaemia and an enlarged spleen. Around 25,000 people in the United States are affected by the disease.
Zavabresib is currently being evaluated in a Phase 1 clinical study as an add-on treatment to ruxolitinib in patients with myelofibrosis who have stopped responding to ruxolitinib alone. The study is being conducted through a collaboration involving academic and research partners in the UK. Data presented in late 2025 showed meaningful reductions in spleen size in a majority of evaluable patients receiving the combination therapy.
The company also confirmed that zavabresib has been approved as the International Nonproprietary Name for OPN-2853.
Orphan Drug Designation is granted to therapies intended to treat rare diseases affecting fewer than 200,000 people in the US. The designation offers regulatory and financial incentives, including tax credits for clinical development, reduced regulatory fees and the possibility of market exclusivity following approval.
Further clinical studies are planned to continue assessing the potential of zavabresib as a new treatment option for patients with myelofibrosis.
Source: businesswire.com
