PTC Therapeutics ($PTCT), reeling from an FDA setback with its Duchenne muscular dystrophy drug, is pulling its application for approval in Canada with plans to submit more clinical data on the twice-failed therapy and boost its odds of success.
The company, headquartered in New Jersey, is nixing its hopes of winning Canadian approval in the first half of this year, withdrawing its application and promising to resubmit the DMD therapy ataluren with results from a recently concluded Phase III trial. PTC believes the new data, disclosed in October, will help it make the case for ataluren's efficacy in a subset of the muscle-wasting DMD.
But the results have yet to impress regulators elsewhere in the world.
In the above-mentioned Phase III trial, ataluren failed its primary endpoint of significantly improving patients' performance on a 6-minute walk test compared with placebo, helping DMD sufferers go only 15 meters farther on average. The miss followed a Phase IIb failure recorded in 2010, but PTC has maintained that subpopulation data from each study suggest ataluren could present benefits to DMD patients with the most trouble walking.
The FDA, reviewing all of PTC's data, hit the company with a refuse-to-file letter last month, citing deficiencies in its application and questioning the company's post hoc analysis. PTC said it is still talking things over with the agency to figure out how to move forward in the U.S.
Ataluren's Phase III failure has also endangered PTC's future in Europe. The European Medicines Agency awarded the drug a conditional OK in 2014, requiring PTC to demonstrate its efficacy in Phase III before granting permanent approval. PTC has since submitted those data to the EMA, and the regulator has declined to disclose a timeline for when it will hand down a final decision on ataluren.
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