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Fostamatinib superior to placebo in chronic ITP
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The first of two double blind, phase 3 studies designed to evaluate fostamatinib in patients with chronic or persistent immune thrombocytopenia met its primary endpoint, according to the agent’s manufacturer.
The randomized, multicenter trial included 76 patients with persistent or chronic immune thrombocytopenia (ITP) who were assigned 2:1 to fostamatinib (Rigel Pharmaceuticals) — an oral spleen tyrosine kinase inhibitor — or placebo twice daily for up to 6 months.
All patients had undergone at least one prior ITP treatment and had blood platelet counts consistently below 30,000/uL of blood.
Stable platelet response — defined as platelet counts at or above 50,000/uL of blood for at least four of the last six clinic visits between weeks 14 and 24 weeks of treatment — served as the primary endpoint.
Eighteen percent of patients assigned fostamatinib achieved stable platelet response compared with none assigned placebo (P = .0261).
ITP treatment typically is intended to increase platelet counts to more than 50,000 uL. Patients in this study who met the primary endpoint had platelet counts increase from a median 16,000 uL at baseline to a median of more than 100,000 uL at week 24.
“We are very encouraged by these results,” Anne-Marie Duliege, MD, executive vice president and chief medical officer of Rigel, said in a company-issued press release. “Consistent with the prior clinical study of fostamatinib in ITP, this ... phase 3 study demonstrated that fostamatinib provided a robust and enduring benefit for those patients who responded to the drug candidate.”
The most common adverse events associated with fostamatinib were gastrointestinal related. Researchers observed no new or unusual safety issues.
“These data demonstrate the potential benefit of fostamatinib for chronic ITP patients who are in need of new treatment options,” Raul Rodriguez, president and CEO of Rigel, said in the release. “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.”
All patients who met the primary endpoint were enrolled in a long-term phase 3 extension study and maintained their platelet levels for months after the initial 24-week study period.
Results of the second phase 3 study are expected later this fall.