Proteostasis Therapeutics, Inc., a clinical stage biopharmaceutical company, engages in the discovery and development of various small molecule therapeutics to treat cystic fibrosis (CF) and other diseases caused by dysfunctional protein processing. The company’s lead product candidates for the treatment of CF include PTI-801, a third generation cystic fibrosis transmembrane conductance regulator (CFTR) corrector agent; PTI-808, a CFTR potentiator; and PTI-428, a CFTR amplifier.