Rigel’s fostamatinib meets main goal in phase 3 study in chronic ITP

The study, which is the first of two double-blind trials in the FIT Phase 3 clinical program, demonstrated that 18% of patients receiving fostamatinib achieved a stable platelet response compared to none receiving a placebo control. 

Rigel said a stable platelet response was defined as achieving more than 50,000 platelets per uL of blood on about four of the final six scheduled visits between weeks 14 and 24 of treatment.

The results from the second study are anticipated in October/November 2016.

Patients who met the study’s primary endpoint had an increase in platelet counts to a level above 50,000/uL within the first weeks of treatment, offering early feedback as to whether it was a viable option for treating their ITP.

Rigel Pharmaceuticals president and CEO Raul Rodriguez said: "These data demonstrate the potential benefit of fostamatinib for chronic ITP patients who are in need of new treatment options.

"We believe that fostamatinib has significant commercial potential given that it has a unique mechanism of action that may work where other products have failed."

Fostamatinib is administered orally as a disodium salt, and is a prodrug of the active compound tamatinib (R-406), which is an inhibitor of the enzyme spleen tyrosine kinase (SYK).

The US Food and Drug Administration granted orphan drug designation to fostamatinib to treat patients with ITP.

Fostamatinib's clinical safety profile includes over 5,000 patient years of data across several autoimmune indications.

Rigel plans to submit a new drug application with the US Food and Drug Administration in the first quarter of 2017 if the present positive results are reproduced in the second phase 3 study and are supported by the results of a proposed interim analysis of the phase 3 extension trial.

Image: Rigel's fostamatinib meets primary endpoint in phase 3 study in Chronic ITP. Photo: courtesy of jk1991 at FreeDigitalPhotos.net.