Dive Brief:
- The Food and Drug Administration on April 17 approved Rigel Pharmaceutical Inc.'s Tavalisse, an oral spleen tyrosine kinase inhibitor designed to prevent autoimmune attacks in chronic immune thrombocytopenia (ITP).
- Across three clinical studies, Rigel measured efficacy by the drug's ability to maintain stable blood platelet response.
- Tacked onto the product approval is an Orphan Drug Designation from the FDA, which allows for a longer period of marketing exclusivity than is typical with a New Drug Application.
Correction: A previous version of this article incorrectly identified the company that currently markets Promacta.
Dive Insight:
The thumbs up for Tavalisse (fostamatinib) comes after a "website error" communicated the news a few days before the approval was official.
ITP is characterized by excessive bruising, bleeding and fatigue, and is associated with an elevated risk of severe bleeding events.
Some examples of drugs used to treat ITP include Amgen Inc.'s second-line drug Nplate (romiplostim) and Novartis AG's Promacta (eltrombopag), both thrombopoietin receptor agonists. These are typically only administered after a patient does not respond to treatment with corticosteroids, intravenous immune globulin (IGIV) or splenectomy.
Despite the number of treatments that are available for ITP, the condition is challenging to tackle because patients with ITP are heterogenous, according to James Bussel, professor emeritus of pediatrics at Weill Cornell Medicine and the principal study investigator on the FIT Phase 3 program.
Rigel saw a market opportunity after learning half of patients with ITP go untreated. "We estimate there are approximately 65,000 adult patients in the U.S. with chronic ITP," Eldon Mayer, chief commercial officer of Rigel, said on the company's fourth quarter earnings call.
"This analysis also revealed that in any given year, approximately 50%, or 32,500, of those patients are not actively treated for their disease. However, over a longer period of time, we expect to see a proportion of those patients join the treated population."
Rigel plans to support Tavalisse's launch with a sales force of between 50 and 60 staff, aiming to commercialize the drug by itself.
"This regulatory milestone, our first product approval, validates the therapeutic effect of SYK inhibition in an autoimmune disease," said Raul Rodriguez, president and CEO of Rigel Pharmaceuticals, in an April 17 statement.
Rigel argues Tavalisse's ability to inhibit a "fundamental target in immune cell signaling" will make it broadly applicable to other autoimmune-related disorders. More specifically, the company is looking at Tavalisse's potential in autoimmune hemolytic anemia.
That hypothesis, however, failed to come to fruition in a Phase 2 study of the drug in IgA nephropathy — a setback that had sunk the company's stock ahead of the recent approval.