PTC soars as EU changes its tune on the DMD-treating ataluren

Comparison of normal translation, incomplete translation and ataluren-facilitated translation of an mRNA into a protein--Courtesy of PTC
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Reversing an earlier rejection, European regulators are recommending early approval for PTC Therapeutics' ($PTCT) ataluren, a treatment for Duchenne muscular dystrophy (DMD), news that more than doubled the biotech's share value in premarket trading.

The drug, to be marketed as Translarna, missed the efficacy mark in a Phase IIb trial, leading Europe's Committee for Medicinal Products for Human Use (CHMP) to rule against granting it a conditional approval in January. PTC appealed that decision, and, upon second consideration, regulators changed their minds on ataluren, clearing the way for a likely near-term launch and sending the biotech's shares up as much as 120% on Friday morning.

With CHMP's recommendation secure, it's now up to the European Commission whether to grant conditional approval for ataluren, a decision usually handed down within three months, according to PTC. The commission generally follows the advice of its advisers, and, if everything works out, the biotech will be able to market its lead drug while it works through its Phase III study, which is expected to complete enrollment by midyear and churn out results in 2015. The EU will hold out on granting full approval until it sees data from that trial.

The reversal comes as a surprise considering CHMP's initial negative read on PTC's data. In its first pass at ataluren's application, the committee pointed out that the drug failed to significantly improve patients' scores on a 6-minute walk test compared to placebo, finding "only limited supportive evidence" that the treatment came through on other measures of efficacy and pointing to insufficient data on how it works in the body.

So what changed?

"During the re-examination, the CHMP took the view that there was some evidence of effectiveness when Translarna is used at a dose of 40 mg/kg/day, and that the way the medicine works is plausible," the group said in its new opinion. Considering the seriousness of DMD and the unmet medical need it presents, PTC's drug is promising enough to merit conditional approval, CHMP wrote.

The committee's 180 is a clear victory for PTC, but, as Merck ($MRK) and partner Endocyte ($ECYT) learned this month, CHMP-motivated goodwill can evaporate in a hurry. The two picked up a conditional approval recommendation for the cancer drug vintafolide in March, sending Endocyte's shares up about 175%. But, just a month and change later, Merck revealed that the ovarian cancer candidate was failing to beat placebo in a Phase III trial, pulling the plug on the study and later yanking the drug's EU application altogether.

However, PTC, even in the worst-case scenario, won't endure such a whiplash. Conditional approval is granted for a year at a time, and the biotech will be able to market ataluren at least until its make-or-break Phase III study wraps up next year.

- read PTC's release
- here's CHMP's opinion (PDF)