Potentiator synergy in rectal organoids carrying S1251N, G551D, or F508del CFTR mutations

Abstract

The potentiator VX-770 (ivacaftor/KALYDECO™) targets defective gating of CFTR and has been approved for treatment of cystic fibrosis (CF) subjects carrying G551D, S1251N or one of 8 other mutations. Still, the current potentiator treatment does not normalize CFTR-dependent biomarkers, indicating the need for development of more effective potentiator strategies. We have recently pioneered a functional CFTR assay in primary rectal organoids and used this model to characterize interactions between VX-770, genistein and curcumin, the latter 2 being natural food components with established CFTR potentiation capacities. Results indicated that all possible combinations of VX-770, genistein and curcumin synergistically repaired CFTR-dependent forskolin-induced swelling of organoids with CFTR-S1251N or CFTR-G551D, even under suboptimal CFTR activation and compounds concentrations, conditions that may predominate in vivo. Genistein and curcumin also enhanced forskolin-induced swelling of F508del homozygous organoids that were treated with VX-770 and the prototypical CFTR corrector VX-809. These results indicate that VX-770, genistein and curcumin in double or triple combinations can synergize in restoring CFTR-dependent fluid secretion in primary CF cells and support the use of multiple potentiators for treatment of CF.

Individualized medicine using intestinal responses to CFTR potentiators and correctors

“…For organoids with very limited swell responses, sufficient dynamic range is present to measure responses to either VX‐770, VX‐809, or the combination, but for organoids displaying considerable (p.Ser1251Asn/p.Phe508del) or high (e.g., p.Arg117His‐7T/p.Phe508del) residual activity, forskolin titrations are needed to improve detection of responses . Compared to ICM biopsies with p.Ser1251Asn which showed relatively poor responses to ex vivo potentiation by VX‐770, VX‐770 clearly potentiated swelling of p.Ser1251Asn organoids, consistent with clinical data from literature . Positive correlations between the efficacy of various CFTR modulators (VX‐770, VX‐809, or the combination) as measured by swelling on various CFTR genetic backgrounds (p.Phe508del homozygous, p.Phe508del/null, p.Ser1251Asn/p.Phe508del, p.Arg117His/p.Phe508del) and their reported outcome in published clinical trials on FEV1 can be established …”

“…The CF‐typical potassium apical secretory response was completely abrogated upon treatment, and chloride‐induced secretory currents upon VX‐770 treatment reached 52%, 63%, and 59% of healthy controls after stimulation of biopsies with forskolin, carbachol, or forskolin + carbachol, respectively. Interestingly, baseline current measurements supported that some CFTR residual function could be detected in p.Gly551Asp subjects, even in the presence of other severe CFTR mutations suggesting that some residual function is associated with this class III gating mutation, albeit more limited as compared to the p.Ser1251Asn gating mutation . It indicates that VX‐770‐repaired p.Gly551Asp remains active for at least some hours in ex vivo biopsies, and points out the value of this biomarker for quantitating an individual's in vivo response to CFTR modulators.…”

“…ICM has been validated across various laboratories, and these studies collectively indicate that this sensitive biomarker of CFTR function shows relations with the CFTR genotype and in vivo clinical features of CF . Only limited studies are available that study the effects of CFTR function enhancing modulators in rectal biopsies ex vivo . Data indicate that CFTR potentiator activity can be detected, albeit that tissue penetrance of drugs during ex vivo administration may limit the study of VX‐770 in this setting .…”

“…The use of direct CFTR‐modulators has been reported at conferences by Derichs et al, and experiences with potentiators in this setting were recently published by us. We studied CFTR potentiation by VX‐770 and genistein in ex vivo rectal biopsies from subjects with the gating mutation p.Ser1251Asn (compound heterozygous with p.Phe508del) or p.Phe508del homozygous subjects . Biopsies were stimulated with forskolin to measure CFTR‐mediated short‐circuit currents, and successively biopsies were stimulated with VX‐770 and genistein.…”

Long-Term Culture of Intestinal Cell Progenitors: An Overview of Their Development, Application, and Associated Technologies

“…bowel reconstruction after disease, could be achieved using de-cellularized scaffolds for growing functional epithelium. The tools of organoid culture have also been explored in single-gene hereditary defects affecting the intestine, notably in studies of the cystic fibrosis transmembrane conductor receptor where organoids derived from the ISCs of cystic fibrosis patients have facilitated functional studies, drug development, personalized medicine, and gene repair approaches to treating the disease [53–55]. Gene manipulation in vivo and ex vivo has led to the conversion of ICPs into insulin producing “neo β-cell islets”, providing a potentially abundant and accessible source of functional insulin producing cells [56].…”