Proteostasis Therapeutics, Inc. and CF Europe announced the completion of enrollment of 502 patients with CF for HIT-CF, a European-based initiative that is paving the path to personalized medicine through the CHOICES clinical trial. CHOICES will test PTI drug combinations in an ex vivo study and then in a clinical trial to assess the predictability of the organoid assay for clinical benefit. For the ex vivo portion, organoids derived from tissue samples provided by patients enrolled in the study are evaluated for responsiveness to investigational CFTR modulators, including Proteostasis' CFTR potentiator, corrector and amplifier, dirocaftor (DIR), posenacaftor (POS) and nesolicaftor (NES), respectively. Based on an individual's organoid response, patients will be invited to progress to the next portion of the study which is a placebo controlled, double blind, crossover study known as the CHOICES trial (Crossover trial based on Human Organoid Individual response in CF - Efficacy Study). The results from CHOICES may serve as the basis for a potential Marketing Authorization Application with the European Medicines Agency (EMA) in 2021 through a novel regulatory pathway. This strategic initiative is led by the HIT-CF consortium, funded through the European Commission's Horizon 2020 program. The CHOICES clinical study is part of PTI's broader clinical development strategy for its CFTR modulator candidates that also includes the MORE trial in CF subjects with the most common F508del homozygous genotype.