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The U.S. Food and Drug Administration has granted orphan drug designation to Pracinostat for the treatment of acute myeloid leukemia. The investigational drug is an oral histone deacetylase (HDAC) inhibitor, and has so far demonstrated evidence of single-agent activity in elderly AML patients in a Phase I dose-escalation trial.

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The Orphan Drug designation-to encourage development of drugs in the diagnosis, prevention, or treatment of a medical condition affecting fewer than 200,000 people in the U.S.-grants a product market exclusivity for a seven-year period if the sponsor complies with certain FDA specifications, as well as tax credits and prescription drug user fee waivers. The designation does not, though, shorten the duration of the regulatory review and approval process.


About 18,860 new cases of AML are expected to be diagnosed this year, according to estimates from the American Cancer Society. The average age at diagnosis is 66.


Pracinostat has been tested in Phase I and II clinical trials in advanced hematologic disorders, as well as in solid tumors in both adult and pediatric patients-having been generally well tolerated in more than 200 patients, with manageable side effects, common to similar drugs. The drug is also currently being tested in Phase II trials in combination with Vidaza (azacitidine) for the treatment of newly diagnosed AML in elderly patients.


Pracinostat is marketed by MEI Pharma, Inc.