Eiger BioPharmaceuticals’ PAH Drug Granted Orphan Drug Status by FDA

Eiger BioPharmaceuticals, Inc., a clinical-stage biopharmaceutical company that focuses on the development and commercialization of drugs for the treatment of rare diseases and conditions with ineffective treatments, announced that ubenimex, a drug developed as a pulmonary arterial hypertension (PAH) therapy, has been granted Orphan Drug Status by the U.S. Food and Drug Administration (FDA).

Ubenimex, also known as Bestatin™, is an oral small molecule drug that inhibits aminopeptidase and leukotriene A₄ hydrolase (LTA₄H), an enzyme responsible for the conversion of leukotriene A4 into leukotriene B4 (LTB₄). LTB₄ is involved in the immune response by activating leukocytes, recruiting neutrophils (immune cells that exacerbate inflammation), and producing reactive oxygen species. By reducing its production, the drug controls and reduces the inflammation onset. Bestatin was developed by the Japanese biopharmaceutical company Nippon Kayaku and is approved in Japan as an adjunct treatment to chemotherapy, maintaining remission and survival in adults with acute non-lymphocytic leukemia. It is not approved for any treatments in Europe or the U.S. As recently reported, Eiger BioPharmaceuticals entered a license agreement with Nippon Kayaku to develop Bestatin for the treatment of pulmonary arterial hypertension (PAH) and other inflammatory diseases involving the same molecular pathway.

The FDA grants orphan drug status to drug candidates aiming to treat rare diseases or conditions that affect less than 200,000 individuals. PAH, a progressive life-threatening disease that can result in heart failure, qualifies for orphan status in the U.S., and also in Europe and Japan. This designation will allow the company to obtain several development advantages for this drug and specific indication, such as tax credits for qualified clinical testing, exemptions from certain costs under the Prescription Drug User Fee Act (PDUFA), and seven-year marketing exclusivity should the drug be approved.

Joanne Quan, MD, Chief Medical Officer at Eiger BioPharmaceuticals, said in a press release, “The FDA Office of Orphan Products Development (OOPD) evaluates scientific and clinical data submissions from sponsors to identify and designate drug candidates that could potentially treat rare diseases to help advance the evaluation and development of such products. We are pleased with the OOPD’s designation of orphan drug status for ubenimex in PAH.”