12 March 2018 - Designation granted for PTI-428 for the treatment of CF patients based on the results from a recent Phase 2, randomised, placebo controlled study.

Proteostasis Therapeutics today announced that the U.S. FDA has granted breakthrough therapy designation for PTI-428, the Company’s cystic fibrosis transmembrane conductance regulator (CFTR) amplifier.

FDA granted the breakthrough therapy designation for PTI-428 for the treatment of CF in homozygous patients for the F508del mutation who are receiving Orkambi as background therapy. The designation was based on the results from a recent Phase 2, randomized, placebo controlled study of PTI-428, in 24 CF subjects on background treatment with Orkambi and who were treated with either 50 mg PTI-428 once daily or placebo for 28 consecutive days. The study results showed that treatment with PTI-428 led to mean absolute improvement in percent predicted forced expiratory volume in 1 second (ppFEV1) of 5.2 percentage points from baseline through Day 28 compared to placebo (p<0.05). Additionally, consistent with the CFTR amplifier mechanism of action, a positive increase in nasal mucosal CFTR protein was observed in PTI-428 treated subjects and the magnitude of change compared to baseline was consistent with the changes in CFTR protein levels observed in the in vitro human bronchial cell model, whereas the placebo subjects had no significant increase in CFTR protein during the treatment period.

Read Proteostasis Therapeutics press release