For greater than a decade, PTC Therapeutics has been going forwards and backwards with the FDA to discover a path ahead for a Duchenne muscular dystrophy drug with a poor monitor report in scientific testing. That effort has come to an finish.

PTC has withdrawn its software for regulatory approval for the drug ataluren, model title Translarna, the corporate introduced after Thursday’s market shut. Based on PTC, the regulator mentioned that based mostly on its investigation up to now, the info within the submission is unlikely to have ample efficacy to assist regulatory approval. The uncommon illness drug developer elaborated in a letter to the U.S. Duchenne neighborhood, saying there have been variations within the interpretation of the info submitted for the drug and that these variations can’t be resolved.

“Regardless of the proof of security and effectiveness demonstrated in a number of scientific trials, the FDA has shared that they contemplate the info to be inadequate to fulfill the approval threshold,” the letter mentioned. “Accordingly, PTC has made the troublesome determination to withdraw the resubmission of the brand new drug software for ataluren.”

Progressive Duchenne muscle weak spot outcomes from a hereditary deficiency of dystrophin, a protein important for muscle perform. A so-called non-sense mutation within the gene that codes for dystrophin prematurely stops manufacturing of the protein, resulting in a shortened and non-functional model. Found internally by PTC, Translarna was developed as a protein restore remedy. This oral small molecule goals to allow a cell’s protein manufacturing equipment to learn the untimely cease sign, permitting the formation of functioning dystrophin. At the very least, that is the way it ought to work.

Translarna failed in section 2 testing. Nonetheless, PTC superior Translarna to Part 3. In 2015, PTC introduced that the drug failed on this placebo-controlled trial. Nonetheless, the corporate pressed forward with a submission to the FDA based mostly on “the totality of the info.” The FDA rejected PTC’s submission in 2017 and has rejected the drugmaker’s subsequent makes an attempt to achieve approval.

For some time, Translarna had higher luck in Europe. In 2014, European regulators granted the drug a conditional advertising authorization, which requires annual renewal till there may be ample knowledge to assist a normal advertising authorization. In 2023 and 2024, PTC challenged a destructive opinion from the European Fee’s Committee for Medicinal Merchandise for Human Use, which had concluded that the drug’s profit had not been confirmed and the authorization shouldn’t be prolonged. Final March, the committee lastly permitted the recommendation and refused the extension.

Though Translarna just isn’t commercially out there within the US, a restricted variety of sufferers have had entry to this drug below the FDA’s Expanded Entry Program. PTC’s letter acknowledged that the corporate will decide subsequent steps within the coming weeks for remaining provides of the drug for these at the moment receiving it.

Translarna is considered one of two PTC medicines for Duchenne. The corporate additionally markets Emflaza, which is permitted within the US however not in Europe. It isn’t clear how Emflaza works in Duchenne, however this drug is a corticosteroid that reduces irritation. Translarna and PTC are PTC’s high merchandise, accounting for $315.6 million in income within the first three quarters of 2025. However PTC faces monetary challenges forward. Translarna will generate marginal income from the remaining markets the place the drug remains to be out there and Emflaza has already misplaced market exclusivity.

The following highest contributor to PTC’s revenues is a brand new product, Sephience. Final summer time, this drug was permitted first in Europe after which within the US as a remedy for the uncommon metabolic illness phenylketonuria. Sephience had $19.5 million in income within the third quarter of 2025. Kebilidi (Upstaza in Europe), a gene remedy permitted in 2024 as a remedy for an ultra-rare enzyme deficiency, generated $15.7 million in income within the first 9 months of 2025.

As for PTC’s pipeline, the corporate remains to be looking for a path ahead for vatiquinone, a drug developed for the uncommon neuromuscular dysfunction Friedreich’s ataxia. The FDA issued a full response letter for this drug final August. PTC had filed a brand new drug software regardless of the small molecule’s failure in section 3 testing.

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