{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,16]],"date-time":"2026-09-16T01:51:01Z","timestamp":1789523461880,"version":"build-2803163510"},"reference-count":45,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2023,6,19]],"date-time":"2023-06-19T00:00:00Z","timestamp":1687132800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Italian Cystic Fibrosis Research Foundation (FFC)","award":["13\/2018"],"award-info":[{"award-number":["13\/2018"]}]},{"name":"Italian Cystic Fibrosis Research Foundation (FFC)","award":["9\/2020"],"award-info":[{"award-number":["9\/2020"]}]},{"name":"Italian Cystic Fibrosis Research Foundation (FFC)","award":["Assael08A0"],"award-info":[{"award-number":["Assael08A0"]}]},{"name":"Lega Italiana Fibrosi Cistica onlus","award":["13\/2018"],"award-info":[{"award-number":["13\/2018"]}]},{"name":"Lega Italiana Fibrosi Cistica onlus","award":["9\/2020"],"award-info":[{"award-number":["9\/2020"]}]},{"name":"Lega Italiana Fibrosi Cistica onlus","award":["Assael08A0"],"award-info":[{"award-number":["Assael08A0"]}]},{"name":"American CFF","award":["13\/2018"],"award-info":[{"award-number":["13\/2018"]}]},{"name":"American CFF","award":["9\/2020"],"award-info":[{"award-number":["9\/2020"]}]},{"name":"American CFF","award":["Assael08A0"],"award-info":[{"award-number":["Assael08A0"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Despite the promising results of new CFTR targeting drugs designed for the recovery of F508del- and class III variants activity, none of them have been approved for individuals with selected rare mutations, because uncharacterized CFTR variants lack information associated with the ability of these compounds in recovering their molecular defects. Here we used both rectal organoids (colonoids) and primary nasal brushed cells (hNEC) derived from a CF patient homozygous for A559T (c.1675G&gt;A) variant to evaluate the responsiveness of this pathogenic variant to available CFTR targeted drugs that include VX-770, VX-809, VX-661 and VX-661 combined with VX-445. A559T is a rare mutation, found in African-Americans people with CF (PwCF) with only 85 patients registered in the CFTR2 database. At present, there is no treatment approved by FDA (U.S. Food and Drug Administration) for this genotype. Short-circuit current (Isc) measurements indicate that A559T-CFTR presents a minimal function. The acute addition of VX-770 following CFTR activation by forskolin had no significant increment of baseline level of anion transport in both colonoids and nasal cells. However, the combined treatment, VX-661-VX-445, significantly increases the chloride secretion in A559T-colonoids monolayers and hNEC, reaching approximately 10% of WT-CFTR function. These results were confirmed by forskolin-induced swelling assay and by western blotting in rectal organoids. Overall, our data show a relevant response to VX-661-VX-445 in rectal organoids and hNEC with CFTR genotype A559T\/A559T. This could provide a strong rationale for treating patients carrying this variant with VX-661-VX-445-VX-770 combination.<\/jats:p>","DOI":"10.3390\/ijms241210358","type":"journal-article","created":{"date-parts":[[2023,6,20]],"date-time":"2023-06-20T01:37:38Z","timestamp":1687225058000},"page":"10358","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":27,"title":["Theratyping of the Rare CFTR Genotype A559T in Rectal Organoids and Nasal Cells Reveals a Relevant Response to Elexacaftor (VX-445) and Tezacaftor (VX-661) Combination"],"prefix":"10.3390","volume":"24","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1267-4814","authenticated-orcid":false,"given":"Karina","family":"Kleinfelder","sequence":"first","affiliation":[{"name":"Department of Medicine, Division of General Pathology, Cystic Fibrosis Laboratory \u201cD. Lissandrini\u201d, University of Verona, 37134 Verona, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Valeria Rachela","family":"Villella","sequence":"additional","affiliation":[{"name":"Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, 80138 Napoli, Italy"},{"name":"CEINGE\u2014Advanced Biotechnologies Franco Salvatore, 80145 Naples, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anca Manuela","family":"Hristodor","sequence":"additional","affiliation":[{"name":"Cystic Fibrosis Centre, Azienda Ospedaliera Universitaria Integrata Verona, 37126 Verona, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Carlo","family":"Laudanna","sequence":"additional","affiliation":[{"name":"Department of Medicine, Division of General Pathology, Cystic Fibrosis Laboratory \u201cD. Lissandrini\u201d, University of Verona, 37134 Verona, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Giuseppe","family":"Castaldo","sequence":"additional","affiliation":[{"name":"Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, 80138 Napoli, Italy"},{"name":"CEINGE\u2014Advanced Biotechnologies Franco Salvatore, 80145 Naples, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0596-2933","authenticated-orcid":false,"given":"Felice","family":"Amato","sequence":"additional","affiliation":[{"name":"Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, 80138 Napoli, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5276-1595","authenticated-orcid":false,"given":"Paola","family":"Melotti","sequence":"additional","affiliation":[{"name":"Cystic Fibrosis Centre, Azienda Ospedaliera Universitaria Integrata Verona, 37126 Verona, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2739-4014","authenticated-orcid":false,"given":"Claudio","family":"Sorio","sequence":"additional","affiliation":[{"name":"Department of Medicine, Division of General Pathology, Cystic Fibrosis Laboratory \u201cD. Lissandrini\u201d, University of Verona, 37134 Verona, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2023,6,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1066","DOI":"10.1126\/science.2475911","article-title":"Identification of the cystic fibrosis gene: Cloning and characterization of complementary DNA","volume":"245","author":"Riordan","year":"1989","journal-title":"Science"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1251","DOI":"10.1016\/0092-8674(93)90353-R","article-title":"Molecular mechanisms of CFTR chloride channel dysfunction in cystic fibrosis","volume":"73","author":"Welsh","year":"1993","journal-title":"Cell"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"220","DOI":"10.1002\/ame2.12180","article-title":"A review of cystic fibrosis: Basic and clinical aspects","volume":"4","author":"Chen","year":"2021","journal-title":"Anim. Model Exp. Med."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"329","DOI":"10.1517\/14728214.12.2.329","article-title":"Emerging drug treatments for cystic fibrosis","volume":"12","author":"Zeitlin","year":"2007","journal-title":"Expert Opin. Emerg. Drugs"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1007\/s00431-015-2664-8","article-title":"Searching for a cure for cystic fibrosis. A 25-year quest in a nutshell","volume":"175","author":"Bosch","year":"2016","journal-title":"Eur. J. Pediatr."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"70","DOI":"10.1016\/j.coph.2017.09.005","article-title":"Where are we with transformational therapies for patients with cystic fibrosis?","volume":"34","author":"Davies","year":"2017","journal-title":"Curr. Opin. Pharmacol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"192","DOI":"10.1016\/j.biocel.2014.02.008","article-title":"Cystic fibrosis: Toward personalized therapies","volume":"52","author":"Ikpa","year":"2014","journal-title":"Int. J. Biochem. Cell Biol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"506","DOI":"10.1002\/humu.23389","article-title":"Cis variants identified in F508del complex alleles modulate CFTR channel rescue by small molecules","volume":"39","author":"Baatallah","year":"2018","journal-title":"Hum. Mutat."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"35","DOI":"10.1016\/j.jcf.2018.03.013","article-title":"The CF Canada-Sick Kids Program in individual CF therapy: A resource for the advancement of personalized medicine in CF","volume":"18","author":"Eckford","year":"2019","journal-title":"J. Cyst. Fibros."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"S32","DOI":"10.1016\/j.jcf.2022.11.007","article-title":"Patient-derived cell models for personalized medicine approaches in cystic fibrosis","volume":"22","author":"Ramalho","year":"2023","journal-title":"J. Cyst. Fibros."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"4258","DOI":"10.1038\/s41467-020-18101-8","article-title":"CFTR trafficking mutations disrupt co-translational protein folding by targeting biosynthetic intermediates","volume":"11","author":"Shishido","year":"2020","journal-title":"Nat. Commun."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"29","DOI":"10.1016\/j.jcf.2013.06.008","article-title":"Effect of ivacaftor on CFTR forms with missense mutations associated with defects in protein processing or function","volume":"13","author":"Yu","year":"2014","journal-title":"J. Cyst. Fibros."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Zacarias, S., Batista, M.S.P., Ramalho, S.S., Victor, B.L., and Farinha, C.M. (2023). Rescue of Rare CFTR Trafficking Mutants Highlights a Structural Location-Dependent Pattern for Correction. Int. J. Mol. Sci., 24.","DOI":"10.3390\/ijms24043211"},{"key":"ref_14","first-page":"3886","article-title":"Maturation and function of cystic fibrosis transmembrane conductance regulator variants bearing mutations in putative nucleotide-binding domains 1 and 2","volume":"11","author":"Gregory","year":"1991","journal-title":"Mol. Cell. Biol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"21","DOI":"10.1038\/ng0992-21","article-title":"Efficiency of gene transfer for restoration of normal airway epithelial function in cystic fibrosis","volume":"2","author":"Johnson","year":"1992","journal-title":"Nat. Genet."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"e154571","DOI":"10.1172\/JCI154571","article-title":"Small-molecule eRF3a degraders rescue CFTR nonsense mutations by promoting premature termination codon readthrough","volume":"132","author":"Lee","year":"2022","journal-title":"J. Clin. Investig."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"939","DOI":"10.1038\/nm.3201","article-title":"A functional CFTR assay using primary cystic fibrosis intestinal organoids","volume":"19","author":"Dekkers","year":"2013","journal-title":"Nat. Med."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"C866","DOI":"10.1152\/ajpcell.00404.2009","article-title":"Influence of cell background on pharmacological rescue of mutant CFTR","volume":"298","author":"Pedemonte","year":"2010","journal-title":"Am. J. Physiol. Cell Physiol."},{"key":"ref_19","first-page":"525","article-title":"Rescue by elexacaftor-tezacaftor-ivacaftor of the G1244E cystic fibrosis mutation\u2019s stability and gating defects are dependent on cell background","volume":"13","author":"Tomati","year":"2022","journal-title":"J. Cyst. Fibros."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"102210","DOI":"10.1016\/j.coph.2022.102210","article-title":"Established and novel human translational models to advance cystic fibrosis research, drug discovery, and optimize CFTR-targeting therapeutics","volume":"64","author":"Cholon","year":"2022","journal-title":"Curr. Opin. Pharmacol."},{"key":"ref_21","first-page":"734","article-title":"A cystic fibrosis patient who is homozygous for the A559T mutation","volume":"57","author":"McDowell","year":"1995","journal-title":"Am. J. Hum. Genet."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"79","DOI":"10.1016\/j.jcf.2008.03.009","article-title":"Consensus on the use and interpretation of cystic fibrosis mutation analysis in clinical practice","volume":"7","author":"Castellani","year":"2008","journal-title":"J. Cyst. Fibros."},{"key":"ref_23","first-page":"41","article-title":"Cystic fibrosis carrier frequencies in populations of African origin","volume":"36","author":"Padoa","year":"1999","journal-title":"J. Med. Genet."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1908","DOI":"10.1093\/hmg\/ddu607","article-title":"Missense variants in CFTR nucleotide-binding domains predict quantitative phenotypes associated with cystic fibrosis disease severity","volume":"24","author":"Masica","year":"2015","journal-title":"Hum. Mol. Genet."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"181","DOI":"10.1590\/S1806-37132013000200009","article-title":"Diagnostic contribution of molecular analysis of the cystic fibrosis transmembrane conductance regulator gene in patients suspected of having mild or atypical cystic fibrosis","volume":"39","author":"Mallmann","year":"2013","journal-title":"J. Bras. Pneumol."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"194","DOI":"10.1016\/j.jcf.2006.07.004","article-title":"CFTR gene analysis in Latin American CF patients: Heterogeneous origin and distribution of mutations across the continent","volume":"6","author":"Luna","year":"2007","journal-title":"J. Cyst. Fibros."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1160","DOI":"10.1038\/ng.2745","article-title":"Defining the disease liability of variants in the cystic fibrosis transmembrane conductance regulator gene","volume":"45","author":"Sosnay","year":"2013","journal-title":"Nat. Genet."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1809","DOI":"10.1056\/NEJMoa1908639","article-title":"Elexacaftor-Tezacaftor-Ivacaftor for Cystic Fibrosis with a Single Phe508del Allele","volume":"381","author":"Middleton","year":"2019","journal-title":"N. Engl. J. Med."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"548","DOI":"10.1016\/j.jcf.2023.03.004","article-title":"FDA-approved drug screening in patient-derived organoids demonstrates potential of drug repurposing for rare cystic fibrosis genotypes","volume":"22","author":"Spelier","year":"2023","journal-title":"J. Cyst. Fibros."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1007\/s00018-016-2385-9","article-title":"Molecular modelling and molecular dynamics of CFTR","volume":"74","author":"Callebaut","year":"2017","journal-title":"Cell Mol. Life Sci."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"344ra84","DOI":"10.1126\/scitranslmed.aad8278","article-title":"Characterizing responses to CFTR-modulating drugs using rectal organoids derived from subjects with cystic fibrosis","volume":"8","author":"Dekkers","year":"2016","journal-title":"Sci. Transl. Med."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"140","DOI":"10.1186\/1465-9921-11-140","article-title":"Mutations that permit residual CFTR function delay acquisition of multiple respiratory pathogens in CF patients","volume":"11","author":"Green","year":"2010","journal-title":"Respir. Res."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"6234","DOI":"10.1038\/s41598-019-42404-6","article-title":"Novel, rare and common pathogenic variants in the CFTR gene screened by high-throughput sequencing technology and predicted by in silico tools","volume":"9","author":"Pereira","year":"2019","journal-title":"Sci. Rep."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"284","DOI":"10.1126\/science.ade2216","article-title":"Molecular structures reveal synergistic rescue of \u0394508 CFTR by Trikafta modulators","volume":"378","author":"Fiedorczuk","year":"2022","journal-title":"Science"},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Capurro, V., Tomati, V., Sondo, E., Renda, M., Borrelli, A., Pastorino, C., Guidone, D., Venturini, A., Giraudo, A., and Mandrup Bertozzi, S. (2021). Partial Rescue of F508del-CFTR Stability and Trafficking Defects by Double Corrector Treatment. Int. J. Mol. Sci., 22.","DOI":"10.3390\/ijms22105262"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"e139983","DOI":"10.1172\/jci.insight.139983","article-title":"Allosteric folding correction of F508del and rare CFTR mutants by elexacaftor-tezacaftor-ivacaftor (Trikafta) combination","volume":"5","author":"Veit","year":"2020","journal-title":"JCI Insight"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"191","DOI":"10.1016\/j.jcf.2004.05.040","article-title":"Established cell lines used in cystic fibrosis research","volume":"3","author":"Gruenert","year":"2004","journal-title":"J. Cyst. Fibros."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"4577","DOI":"10.1038\/sj.onc.1205550","article-title":"Immortalization and transformation of primary human airway epithelial cells by gene transfer","volume":"21","author":"Lundberg","year":"2002","journal-title":"Oncogene"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"405","DOI":"10.1007\/s00441-005-0062-7","article-title":"Towards an in vitro model of cystic fibrosis small airway epithelium: Characterisation of the human bronchial epithelial cell line CFBE41o-","volume":"323","author":"Ehrhardt","year":"2006","journal-title":"Cell Tissue Res."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"444","DOI":"10.1038\/nchembio.1253","article-title":"Mechanism-based corrector combination restores \u0394F508-CFTR folding and function","volume":"9","author":"Okiyoneda","year":"2013","journal-title":"Nat. Chem. Biol."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"1612","DOI":"10.1056\/NEJMoa1807120","article-title":"VX-445-Tezacaftor-Ivacaftor in Patients with Cystic Fibrosis and One or Two Phe508del Alleles","volume":"379","author":"Keating","year":"2018","journal-title":"N. Engl. J. Med."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"895","DOI":"10.1016\/j.jcf.2021.03.011","article-title":"Elexacaftor co-potentiates the activity of F508del and gating mutants of CFTR","volume":"20","author":"Veit","year":"2021","journal-title":"J. Cyst. Fibros."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"2002774","DOI":"10.1183\/13993003.02774-2020","article-title":"Rescue of multiple class II CFTR mutations by elexacaftor + tezacaftor + ivacaftor mediated in part by the dual activities of elexacaftor as both corrector and potentiator","volume":"57","author":"Laselva","year":"2021","journal-title":"Eur. Respir. J."},{"key":"ref_44","doi-asserted-by":"crossref","unstructured":"Kleinfelder, K., Somenza, E., Farinazzo, A., Conti, J., Lotti, V., Latorre, R.V., Rodella, L., Massella, A., Tomba, F., and Bertini, M. (2023). CFTR Modulators Rescue the Activity of CFTR in Colonoids Expressing the Complex Allele p.[R74W;V201M;D1270N]\/dele22_24. Int. J. Mol. Sci., 24.","DOI":"10.3390\/ijms24065199"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"742","DOI":"10.1002\/humu.23741","article-title":"Two CFTR mutations within codon 970 differently impact on the chloride channel functionality","volume":"40","author":"Amato","year":"2019","journal-title":"Hum. Mutat."}],"container-title":["International Journal of Molecular Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1422-0067\/24\/12\/10358\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T19:56:47Z","timestamp":1760126207000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1422-0067\/24\/12\/10358"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,6,19]]},"references-count":45,"journal-issue":{"issue":"12","published-online":{"date-parts":[[2023,6]]}},"alternative-id":["ijms241210358"],"URL":"https:\/\/doi.org\/10.3390\/ijms241210358","relation":{},"ISSN":["1422-0067"],"issn-type":[{"value":"1422-0067","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,6,19]]}}}