Astellas Wins FDA Panel Backing for Overactive Bladder Drug

Astellas Pharma Inc. (4503)’s mirabegron treatment for overactive bladders won the backing of advisers to U.S. regulators despite the drug being linked to high blood pressure and other side effects. The stock rose.

A Food and Drug Administration advisory panel voted 7-4 to recommend approving the drug yesterday, saying mirabegron is beneficial and adequately safe. The agency isn’t required to follow the panel’s recommendations and is scheduled to decide by June 29.

Mirabegron would be the first in a new class of treatments for sudden urination-urge conditions that affect 42 million people in the U.S., Tokyo-based Astellas said. Sales of the drug would help Astellas buffer a decline in revenue when its Vesicare bladder-control drug, which generated $1 billion in sales last fiscal year, loses patent protection in 2015.

“I was excited to find another class of drugs that may offer some benefit for my patients,” Juana Hutchinson-Colas, assistant professor of obstetrics and gynecology at Robert Wood Johnson Medical School in New Brunswick, New Jersey, and a panel member, said during the meeting.

Astellas shares rose 3.2 percent, the biggest gain since Nov. 4, to 3,360 yen as of the 3 p.m. close in Tokyo trading, while the benchmark Topix Index fell 0.8 percent.

The panel also voted 8-4 that mirabegron is beneficial and 9-3 that it’s adequately safe. Panel members who voted that the drug is safe said Astellas needs to conduct follow-up studies to better understand the side effects.

Blood Pressure

The drug increased heart rates in addition to blood pressure and was associated with hypersensitivity reactions ranging from painful rash to anemia, FDA staff wrote in an April 3 report. The treatment also was linked to tests revealing potential liver disease, a small number of urinary tract infections and malignant tumors, FDA staff wrote. The reason mirabegron would lead to tumor formation is unknown.

The drug reduced the number of times patients were incontinent, or involuntarily urinated, in a 24-hour period, the staff wrote. Patients experienced mean 2.7 incontinence episodes daily at the start of final-phase studies. Of the 862 patients on mirabegron, the episodes decreased to 1.2 incidents, compared to 1.6 for the 878 patients on placebo, according to the report.

While the FDA said the reduction is statistically significant, Kate Ryan, program coordinator at the Washington- based National Women’s Health Network, told the committee they are inadequate.

Uniqueness of Drug

“These women want a real solution,” Ryan said. “One that is effective enough to make a practical solution in their real life. Unfortunately this drug just doesn’t do that.”

Panel members said the uniqueness of mirabegron made them vote in favor of its approval.

Drugs on the market to treat overactive bladder block a receptor that causes contractions that make someone feel the urge to urinate though they also can affect the ability to empty the bladder, Martin said. Mirabegron enhances bladder storage without affecting patients’ ability to urinate.

Current treatments include Pfizer Inc. (PFE)’s Detrol, Warner Chilcott Plc (WCRX)’s Enablex and Astellas’s Vesicare.

Patients also often stop taking drugs on the market because of dry mouth, according to Martin. She said incidents of dry mouth with mirabegron were similar to placebo.

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