The US Food and Drug Administration (FDA) has granted Fast Track designation to Dimension Therapeutics Inc's lead product candidate, DTX101, for the treatment of haemophilia B.

Dimension expects to initiate a multi-center phase 1/2 study to evaluate DTX101 in adult patients with moderate/severe to severe haemophilia B by the end of 2015.

DTX101 is designed to deliver blood clotting factor IX (FIX) gene expression in patients with haemophilia B. Haemophilia B is a rare genetic bleeding disorder resulting from a deficiency in FIX. The current standard of care for patients with haemophilia B involves chronic replacement of FIX protein through intravenous infusion. In 2013, the World Federation of Haemophilia estimated there were more than 28,000 haemophilia B patients worldwide, including 4,000 patients in the United States.

The FDA’s Fast Track programme is designed to facilitate and expedite development and review of new drugs to treat serious or life-threatening conditions and address unmet medical need. Through the Fast Track programme, a product may be eligible for priority review at the time of BLA and may be eligible to submit sections of the BLA on a rolling basis as data become available. In addition there are opportunities for frequent interactions with FDA with this designation.

“We are very pleased to achieve this additional important milestone for our DTX101 programme, following the FDA’s recent acceptance of Dimension’s investigational new drug (IND) application and granting of orphan drug designation for our lead candidate,” said Annalisa Jenkins, MBBS, MRCP, Dimension’s chief executive officer. “This latest development provides further momentum as we advance DTX101, with the near-term goal to initiate our clinical trial by the end of this year.”

Dimension is developing its lead gene therapy product DTX101, which is expected to enter clinical development in 2015, for the treatment of moderate/severe to severe haemophilia B. DTX101 is designed to deliver FIX, gene expression in a durable fashion, preventing the long-term complications of haemophilia B. Preclinical studies completed to date indicate DTX101 has the potential to be a well-tolerated, effective therapy for haemophilia B.