Rigel Granted First FDA Approval for Chronic ITP Therapy

This afternoon, Rigel Pharmaceuticals, Inc. announced that the U.S. Food and Drug Administration (FDA) approved fostamatinib disodium hexahydrate (Tavalisse) tablets for the treatment of thrombocytopenia in adult patients with chronic immune thrombocytopenia.

The oral spleen tyrosine kinase (SYK) inhibitor targets the underlying autoimmune cause of the disease by impeding platelet destruction, and is intended for patients who have had an insufficient response to previous treatment.

Data from the Phase 3 FIT clinical program for fostamatinib in ITP supports the FDA’s decision to approve the drug; it was comprised of results from 3 studies, 2 randomized placebo-controlled studies and the third of which was an open-label extension study. An initial proof of concept study was also included. The New Drug Application (NDA) that was submitted by Rigel to the FDA was comprised of data from 163 ITP patients and supported by a safety database of more than 4,600 subjects across other indications in which fostamatinib has been evaluated.

James Bussel, M.D., professor emeritus of pediatrics at Weill Cornell Medicine and the principal study investigator on the FIT Phase 3 program, and has served as a consultant and paid member of the advisory board for Rigel Pharmaceuticals, Inc.

"Chronic ITP is challenging to treat because the heterogeneity of the disease makes it difficult to predict how an individual patient will respond to available treatments and not all patients can find a treatment that works well for them," said Dr. Bussel in the official press release. "The FDA approval of fostamatinib arms physicians with a new treatment option, which works via a novel mechanism."

Fostamatinib is Rigel’s first approved therapeutic. The company expects it to be available by prescription by the end of the second quarter 2018.

"People living with chronic ITP often feel they have an invisible disease -- one that can not only impact quality of life, but also be life threatening," said Caroline Kruse, executive director of the Platelet Disorder Support Association, a patient advocacy organization dedicated to ITP patients. "That's why we encourage members of our community to learn about their disease, understand treatment strategies, and seek support so that they can advocate for their best care. The availability of a new treatment option provides the ITP community with more choices."

Rigel has noted that common adverse reactions (≥5% and more common than placebo) from the FIT-1 and FIT-2 studies included: diarrhea, hypertension, nausea, dizziness, ALT and AST increased, respiratory infection, rash, abdominal pain, fatigue, chest pain, and neutropenia.

Serious adverse drug reactions in the ITP double-blind studies included: febrile neutropenia, diarrhea, pneumonia, and hypertensive crisis, which occurred in 1% of TAVALISSE patients. In addition, severe adverse reactions occurred including dyspnea and hypertension, neutropenia, arthralgia, chest pain, diarrhea, dizziness, nephrolithiasis, pain in extremity, toothache, syncope, and hypoxia.

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