Correctors and Potentiators Rescue Function of the Truncated W1282X-Cystic Fibrosis Transmembrane Regulator ( CFTR) Translation Product*

W1282X is the fifth most common cystic fibrosis transmembrane regulator (CFTR) mutation that causes cystic fibrosis. Here, we investigated the utility of a small molecule corrector/potentiator strategy, as used for Delta F508-CFTR, to produce functional rescue of the truncated translation product of the W1282X mutation, CFTR1281, without the need for readthrough. In transfected cell systems, certain potentiators and correctors, including VX-809 and VX-770, increased CFTR1281 activity. To identify novel correctors and potentiators with potentially greater efficacy on CFTR1281, functional screens were done of similar to 30,000 synthetic small molecules and drugs/nutraceuticals in CFTR1281-transfected cells. Corrector scaffolds of 1-arylpyrazole-4-arylsulfonyl-piperazine and spiro-piperidine-quinazolinone classes were identified with up to similar to 5-fold greater efficacy than VX-809, some of which were selective for CFTR1281, whereas others also corrected Delta F508-CFTR. Several novel potentiator scaffolds were identified with efficacy comparable with VX-770; remarkably, a phenylsulfonamide-pyrrolopyridine acted synergistically with VX-770 to increaseCFTR(1281) function similar to 8-fold over that of VX-770 alone, normalizing CFTR1281 channel activity to that of wild type CFTR. Corrector and potentiator combinations were tested in primary cultures and conditionally reprogrammed cells generated from nasal brushings from one W1282X homozygous subject. Although robust chloride conductance was seen with correctors and potentiators in homozygous Delta F508 cells, increased chloride conductance was not found in W1282X cells despite the presence of adequate transcript levels. Notwithstanding the negative data inW1282Xcells from one human subject, we speculate that corrector and potentiator combinations may have therapeutic efficacy in cystic fibrosis caused by the W1282X mutation, although additional studies are needed on human cells from W1282X subjects.