- PTC Therapeutics on Tuesday revealed the FDA had rejected the New Jersey-based biotech's drug application for its lead Duchenne muscular dystrophy (DMD) candidate. The "refusal to file" letter indicated the application was incomplete, leaving the FDA unable to review the drug.
- Following the announcement of the letter, PTC stock plummeted, shedding 61% of its value in Tuesday trading. It has continued to fall Wednesday.
- This is the second refusal to file letter sent by the FDA in as many weeks. The regulator last Thursday sent a letter to Catalyst Pharmaceuticals rejecting its NDA for firdapse, a drug for the treatment of Lamber-Eaton Myasthenic Syndrome.
PTC Therapuetics is developing ataluren, or Translarna, as an oral treatment of nonsense mutation DMD. In 2014, Translarna received license in the European Economic Area (the EU plus three countries) in patients five years or older. However, as FierceBiotech notes, that licensure was predicated on the success of the phase 3 trial which PTC unsuccessfully used in its FDA submission.
DMD patients and advocates have been disappointed by a recent string of drug failures in the US. In January, the FDA strongly questioned the clinical trial data of Sarepta Therapeutics' DMD therapy eteplirsen, casting doubt on the outcome of the FDA's review.
This news came directly on the heels of the FDA's rejection of BioMarin's competing drug dirsapersen.
PTC's drug targeted a smaller segment of the overall DMD portion, aiming to treat those suffering from nonsense mutations (nmDMD). PTC estimates the patient population of nmDMD to be 2,000 patients in the US.