Catalyst’s Recombinant Factor IX Variant for Hemophilia B Wins FDA Orphan Drug Status

The U.S. Food and Drug Administration (FDA) has granted orphan drug status (ODD) to Catalyst Biosciences’ highly potent recombinant human factor IX variant CB 2679d (also known as ISU304) to treat hemophilia B.

Catalyst is evaluating CB 2679d’s potential for subcutaneous prophylactic treatment in people with hemophilia B. The regulatory decision follows Catalyst’s completion of dosing of the first subcutaneous group in an ongoing Phase 1/2 proof-of-concept trial (NCT03186677) in South Korean patients with severe hemophilia B.

The San Francisco-based company announced positive first results of the proof-of-concept trial showing that an intravenous dose of CB 2679d was nearly 22 times more potent than a similar dose of BeneFIX (Pfizer’s standard-of-care replacement therapy).

These first results also suggested that CB 2679d circulated in the bloodstream for an average 34 hours, compared to 25 hours for BeneFIX. Interim top-line results are expected by year’s end, with complete trial results by early 2018.

The FDA’s orphan drug status means Catalyst will be eligible to receive certain incentives to support clinical trials and, possibly, see CB 2679d come to market faster if clinical trials go as planned.

“Receipt of FDA orphan status will support the development of this promising subcutaneous treatment option for individuals with hemophilia B,” Dr. Nassim Usman, president and CEO of Catalyst, said in a press release. “Notable benefits of ODD include the potential for seven years of market exclusivity. Assuming our ongoing clinical development program is successful, this important designation will bolster the rapid availability of CB 2679d for subcutaneous prophylaxis in this life-threatening and chronically debilitating disorder.”

Catalyst is conducting the proof-of-concept trial in collaboration with ISU Abxis. Once it completes the trial’s Phase 1 portion, Catalyst will have development and commercial rights to the drug outside South Korea.

The European Medicines Agency (EMA) also granted CB 2679d orphan medicinal product designation in June 2017 to treat hemophilia B. The EMA designation also gives 10 years of exclusive marketing rights to therapies, among other benefits.