NHLBI is soliciting applications from small businesses to develop and validate novel in vitro human cell-based tools for predicting the responses of individual patients to cystic fibrosis transmembrane conductance regulator (CFTR)-directed therapeutics for cystic fibrosis (CF) lung disease. Proposed research projects are expected to focus on the development of highly innovative cell-based systems that recapitulate a patient-specific CFTR phenotype to create a personalized study platform to examine response to CFTR-directed therapeutics. The models developed must be based on live cells from humans harboring CFTR mutations associated with CF. While the primary goal of this initiative is to promote precision medicine and optimization of treatment at the personal level, it may also yield as a secondary benefit the ability to select appropriate treatments for CF at an earlier age.