Rigel’s Tavalisse Flunks Kidney Disease Trial

Rigel Pharmaceuticals Raul Rodriguez

As Rigel Pharmaceuticals awaits a regulatory decision for Tavalisse (fostamatinib) for a platelet disorder, the company reported a developmental setback for the therapy in another trial. Investors began dumping shares and the stock was down nearly 10 percent in premarket trading this morning following news the therapy flunked a mid-stage kidney disease trial.

Bay Area-based Rigel released topline data from its Phase II proof of concept study of fostamatinib in patients with IgA nephropathy (IgAN), an orphan kidney disease. The company said the trial did not achieve statistical significance for its primary endpoint of mean change in proteinuria (protein in the urine) between patients on the Rigel therapeutic and placebo over a six-month period.

In its announcement this morning the company did try to salvage some good news. The company said a subgroup of patients with more than one gram per day of proteinuria at baseline saw a reduction of in proteinuria in fostamatinib-treated patients relative to placebo patients. While the company singled out that subgroup, it quickly pointed to the fact that the data from that group failed to show statistical significance.

"We find the subgroup analysis encouraging because patients and physicians have been challenged to manage this serious disease that has no approved treatment options," Raul Rodriguez, president and chief executive officer of Rigel said in a statement. "This study has provided valuable information on the potential benefit of fostamatinib in IgA nephropathy patients with significant need, those with greater than 1 gram/day of proteinuria. We will continue to evaluate the data to determine the best path forward in this indication."

Frederick Tam, chair of renal medicine in the Department of Medicine at Imperial College of London, which partnered with Rigel in the study, said there are no specific therapies or treatment algorithms for IgAN patients. He said it’s important to identify a possible solution to reduce the risks of complications from the disease. If the proteinuria cannot be reduced in patients there is a higher risk of kidney function loss, Tam said.

IgA nephropathy, which is also known as Berger's disease, is a chronic autoimmune disease associated with inflammation in the kidneys that diminishes their ability to filter blood. The disease affects between 83,000 and 165,000 people in the United States. Rigel said about 25 percent of IgAN cases result in end-stage renal failure requiring dialysis or kidney transplantation.

The company said it will continue to examine the data from the mid-stage trial. Additionally, Rigel said it will seek a developmental partner to collaborate in the conduct of follow-on clinical studies in IgAN. The partner would be given commercialization rights of fostamatinib outside of the United States, Rigel said.

Two years ago the company reported a failure of fostamatinib in adult chronic/persistent immune thrombocytopenia and rheumatoid arthritis.

Later this month the company is expecting a decision from the U.S. Food and Drug Administration for Tavalisse (fostamatinib disodium) as a treatment for adult patients with chronic or persistent immune thrombocytopenia (ITP). ITP is a rare autoimmune disorder that affects about 65,000 people in the United States. The disease attacks and destroys the body's own blood platelets, which play an active role in blood clotting and healing. 

Rigel is also studying the effects of Tavalisse on patients with autoimmune hemolytic anemia (AIHA), a disorder similar to ITP, but where antibodies attack red blood cells rather than platelets. There is no FDA approved treatment for the approximately 40,000 patients in the U.S. with this disease.

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