(600) A multimodal iPSC platform for cystic fibrosis drug testing

Background: Cystic fibrosis (CF) is a monogenic lung disease caused by dysfunction of the CFTR anion channel, resulting in significant morbidity and mortality. The progress in elucidating the role of CFTR using established animal and cell-based models led to the recent discovery of effective modulators for most individuals with CF. However, a subset of individuals with CF do not respond to these modulators and there is an urgent need to develop novel therapeutic strategies.

Methods: Here, we have assembled a panel of induced pluripotent stem cells (iPSCs) derived from individuals with common or rare CFTR variants representative of three distinct classes of CFTR dysfunction. Utilizing new advances in iPSC directed differentiation protocols, we have generated airway epithelial cells from 12 iPSC lines, encompassing unaffected (healthy) donors as well as donors with Class 1-3 CFTR mutations. We have adapted two functional assays for the detection of baseline as well as rescued function of the CFTR channel.

Results: In both a 3-D spheroid assay (Figure 1a) using forskolin-induced swelling (FIS) as well as planar cultures composed of polarized mucociliary airway epithelial cells (Figure 1b), we quantified CFTR baseline function and response to CFTR modulators and detected genotype-specific differences. We detected CFTR-genotype specific responses that show negligible function at baseline for Phe508del, G551D, W1282X, and G542X samples, however after treatment with known therapeutics, we detected functional rescue of Phe508del and G551D samples. Treatment of premature termination codon (PTC) variants (W1282X, G542X) with experimental CFTR therapeutics (such as non-sense mediated decay inhibitors and PTC read through agents) partially restore function in iPSC-derived airway epithelial cells. Comparison to primary W1282X HBECs showed a remarkable similarity in amplitude and pattern of response to combinatorial therapeutics (Figure 1c).

Conclusions: Our results demonstrate the potential of the human iPSC platform as a research tool to study CF and in particular accelerate therapeutic development for CF caused by rare variants.

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