The US Food and Drug Administration (FDA) has granted Orphan Drug designation to Rigel Pharmaceuticals Inc's Fostamatinib, an oral spleen tyrosine kinase (SYK) inhibitor which is currently in phase 3 clinical studies in patients with chronic immune thrombocytopenic purpura (ITP).

Rigel's phase 3 programme for Fostamatinib in ITP, called FIT, has surpassed the half-way point in enrollment and Rigel expects the programme to read out results in mid-2016.

"Receiving this Orphan Drug designation from the FDA is a positive step forward in the development of Fostamatinib," said Raul Rodriguez, president and chief executive officer of Rigel.

"We look forward to completing our phase 3 programme and intend to file a New Drug Application for Fostamatinib in ITP in the US," he added.

In patients with ITP, the immune system attacks and destroys the body's own blood platelets, which play an active role in blood clotting and healing. ITP patients can suffer extraordinary bruising, bleeding and fatigue as a result of low platelet counts. Current therapies for ITP include steroids, blood platelet production boosters (TPOs) and splenectomy. Rigel believes that Fostamatinib may address the autoimmune basis of the disease.

Orphan Drug designation is granted to compounds that are in development for the safe and effective treatment, diagnosis or prevention of rare diseases or disorders that affect fewer than 200,000 people in the United States. This designation can provide numerous benefits to the companies developing these drugs for these indications, including possibly a market exclusivity period, tax credits, waived FDA fees and research and development grants and others.

Rigel Pharmaceuticals, Inc. is a clinical-stage biotechnology company focused on the discovery and development of novel, small-molecule drugs for the treatment of immune diseases and cancers.