PTC Therapeutics Drug Doesn't Meet Goal in Duchenne Trial

  • Translarna didn't show significant benefit in walk test
  • PTC continuing with FDA submission, preparing for launch

PTC Therapeutics Inc.’s drug for the rare disorder Duchenne muscular dystrophy failed to help boys with the muscle-wasting disease walk better in a final-stage clinical trial, the company said.

In a trial of 228 patients, PTC measured how far the boys could walk in six minutes. Those on the drug went 15 meters further than those given a placebo, a difference that is not considered statistically significant, according to a statement on Thursday.

Patients with moderate disease were most likely to benefit, going 47 meters farther during the walk test, a significant difference. None of the boys in this subgroup lost their ability to walk during the trial, compared with four getting a placebo, according to the statement. PTC also pooled together data from the phase 3 study and a previous study, and in the meta-analysis, the difference in the six-minute walk test was a significant benefit of 22 meters, PTC said in an e-mail. Shares rose 4 percent to $33 in extended trading in New York.

Christopher Marai, an analyst at Oppenheimer & Co., said the meta-analysis will probably be enough to convince regulators to approve the drug.

“We believe these results will be enough to keep Translarna on the market in the EU and garner FDA approval in the US,” Marai wrote in a note to clients, referring to the U.S. Food and Drug Administration.

‘Totality’ of Data

The company also said the findings may be enough to persuade regulators to back the drug.

“We’re excited because the totality of the clinical data do confirm the benefit we previously saw in the Phase 2 study and, in our perspective, supports the benefit of Translarna,” PTC Chief Financial Officer Shane Kovacs said in an interview. PTC will complete its application to the FDA by year-end and is “actively preparing for a commercial launch in 2016,” he said.

Cowen & Co. analyst Ritu Baral said in an interview before the data release that the trial had a “greater than 50 percent chance” of being successful and that she hoped to see patients walking 30 meters further on the drug. Thirty meters is “the threshold of clinical meaningfulness,” she said by telephone.

Muscle Degeneration

Duchenne is a genetic disorder that affects about 1 in 3,500 boys, causing progressive muscle degeneration. A mutated gene on the X chromosome prevents patients from producing the protein dystrophin, which is needed to support muscles. DMD puts kids in wheelchairs before their teens, and patients often die by their 20s. There is no approved treatment in the U.S.

The FDA is urgently considering drugs to treat DMD, Chief Executive Officer Stuart Peltz said on a call with investors after results were released.

PTC’s drug Translarna works for those boys who have a “nonsense” mutation, which the company estimates as affecting 13 percent of patients, or about 2,000 boys in the U.S. and 2,500 in Europe. The nonsense mutation acts like a period in the middle of a sentence, prematurely stopping the manufacturing of the protein. The drug is intended to help the body read through the stop signal and produce a complete protein.

European Approval

Translarna has received conditional approval in the European Union. If it’s approved in the U.S., the drug is expected to achieve annual sales in the U.S. and Europe of as much as $900 million at its peak, based on an estimated price tag of $300,000 a year, according to RBC Capital Markets analyst Simos Simeonidis.

In draft guidance, the U.K.’s medical payments review agency rejected PTC’s drug on Thursday and asked the company to provide more evidence that it worked. The agency said its guidance wasn’t final and hadn’t taken the latest study into account.

High prices of specialty drugs have been in the spotlight recently, criticized by politicians in the U.S. and in Europe. British Prime Minister David Cameron criticized Translarna’s price on Wednesday when asked by member of Parliament Cheryl Gillan about the availability of the drug in the U.K.

Translarna “and other drugs like it can cost over 400,000 pounds per patient per year,” Cameron said. “What we need to do, as well as making sure these decisions are made by clinicians rather than politicians, is talk to the drug companies about trying to bring the cost of some of these drugs down.”

Translarna’s price depends on the patient’s weight, and has a list price of about $300,000 (194,000 pounds), according to PTC. Kovacs said there are about 50 to 100 patients eligible for Translarna in the U.K., making it an “ultra orphan” disease. “The impact to the U.K. budget in aggregate would be negligible,” he said.

‘Optimal Window’

While the study announced by PTC on Thursday showed that patients with “moderate disease” may be in the “optimal window” for the drug, Kovacs said he didn’t expect regulators to limit the drug’s use to those patients, since Translarna doesn’t just benefit muscle tissue but also should improve respiratory and cardiac function.

PTC, based in South Plainfield, New Jersey, also is testing Translarna in patients with cystic fibrosis, which could generate an additional $1.3 billion in peak sales, according to Simeonidis.

BioMarin Pharmaceutical Inc. and Sarepta Therapeutics Inc. are working on DMD drugs that rely on a different mechanism and target a different set of patients.

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