Big gain for Proteostasis on Phase I data for CF doublet

Proteostasis Therapeutics Inc. (NASDAQ:PTI) jumped $8.46 (448%) to $10.35 on Thursday after reporting that its doublet cystic fibrosis therapy improved percent predicted forced expiratory volume in 1 second (ppFEV1) and sweat chloride levels in a Phase I trial. The doublet therapy comprised CF transmembrane conductance regulator (CFTR) corrector PTI-801 and CFTR potentiator PTI-808. Proteostasis reported the data after market close on Wednesday.

In five evaluable CF patients in the mid-dose cohort, once-daily 300 mg oral PTI-801 plus 300 mg PTI-808 significantly increased mean absolute ppFEV1 by 6.3 percentage points at day seven (p=0.009) and by 5.9 percentage points at day 14 (p=0.008) compared with baseline. Compared with placebo, the mid-dose doublet therapy significantly increased mean absolute ppFEV1 from baseline to day seven by 8.3 percentage points (p=0.026) and to day 14 by 6.6 percentage points (p=0.042)...