Opna Bio received Orphan Drug Designation from the FDA for its drug OPN-2853, which was given the generic name zavabresib[1]. It is a small molecule that inhibits BET (bromodomain and extra-terminal motif) proteins and is intended for the treatment of myelofibrosis, a rare and serious type of blood cancer[1]. Myelofibrosis is characterized by scarring of the bone marrow, leading to ineffective blood cell production and symptoms such as extreme fatigue, an enlarged spleen, and anemia[1]. Approximately 25,000 people in the United States are affected by the disease[1]. Clinical trials combining zavabresib with ruxolititinib (a different type of drug) have shown impressive results, including a permanent reduction in spleen size in patients with advanced myelofibrosis[1]. Orphan drug designation brings benefits including tax breaks for clinical trials, the waiver of certain FDA fees, and the right to seven years of market exclusivity upon approval[1].