Optimer Wins U.S. Approval for Drug to Fight Fatal Bacteria

Optimer Pharmaceuticals Inc. won U.S. approval for the first antibiotic in a quarter-century that fights a deadly bacterium linked to intestinal infections often caught in hospitals.

The Food and Drug Administration cleared fidaxomicin, the agency said today in a statement. Optimer will sell the drug under the name Dificid.

Dificid will be San Diego-based Optimer’s initial product and the first drug cleared in more than 25 years for Clostridium difficile, which attacks the lining of the colon and can cause severe diarrhea. The germ sickens about 500,000 people a year in the U.S. and kills about 30,000, according to the Centers for Disease Control and Prevention. Optimer plans to start selling the treatment as early as July, Chief Financial Officer John Prunty said in a telephone interview.

“We think this will give us an opportunity to bring this drug to patients who have a significant unmet need” for treating their C. difficile infections, Prunty said.

Sales of the drug may surpass $217 million in 2015, according to the average estimate of three analysts surveyed by Bloomberg. The treatment may generate as much as $500 million worldwide, said Alan Carr, a Needham and Co. analyst.

Optimer declined $1.01, or 7.2 percent, to $12.98 at 4 p.m. New York time in Nasdaq Stock Market trading. The shares have gained 14 percent this year.

Unanimous Backing

The company rose 11 percent -- the most in 22 months -- on April 1 after FDA staff reviewers said fidaxomicin is as effective as ViroPharma Inc.’s vancomycin in curing illnesses and prevented more recurrences in clinical trials. A 13-member FDA advisory panel unanimously backed the drug on April 5.

Optimer and Cubist Pharmaceuticals Inc. will jointly market the drug to U.S. health-care providers under a two-year agreement the companies announced last month.

The FDA evaluated fidaxomicin under a six-month priority review and aimed to make a decision by May 30. While the FDA typically takes at least 10 months to rule on drug applications, it grants priority status to therapies that may provide major advances in treatment.

An Optimer-funded study of 548 patients found that infections subsided in 88 percent of those treated with fidaxomicin and 86 percent of those taking vancomycin, the only drug approved by the FDA for C. difficile infections.

Cut Recurrence

Fidaxomicin also cut the recurrence rate by almost half, according to a Feb. 2 report in the New England Journal of Medicine. About 13 percent of patients who took Optimer’s drug suffered relapses, compared with 24 percent of those treated with vancomycin.

FDA staff said in last month’s report that they agreed with the company’s conclusions about the drug’s efficacy, and found the overall incidence of side effects with fidaxomicin was similar to that of vancomycin.

Members of the agency’s advisory panel split last month, in a 6-6 vote, on whether the company’s data on recurrence prevention was clinically significant.

The final prescribing language backed the company’s claims about the drug’s ability to prevent recurrences more effectively than vancomycin, said Needham’s Carr.

“It does call out the benefits of Dificid over vancomycin in preventing recurrence over 25 days after the end of treatment,” Carr said.

At Risk

People ages 65 and older are among those most at risk for C. difficile illnesses, according to the Mayo Clinic in Rochester, Minnesota. Infections often strike after a patient is treated with antibiotics that destroy the good bacteria normally found in the intestine. About 25 percent of patients suffer relapses.

Optimer’s drug is the first in a new class of antibiotics that kill harmful bacteria by inhibiting an enzyme known as RNA polymerase without weakening the normal intestinal flora, according to a company fact sheet.

Vancomycin, approved by the FDA in 1986 for the infection under the brand name Vancocin, is one of two standard C. difficile treatments. The other is an unapproved use of metronidazole, sold by Pfizer Inc. as Flagyl and available in generic form. ViroPharma bought Vancocin from Eli Lilly & Co. in 2004.

Optimer’s drug is the 16th novel medicine approved by the FDA this year, suggesting the agency may top its tally of 21 new drugs approved in 2010.

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