Effectiveness of PTC124 treatment of cystic fibrosis caused by nonsense mutations: a prospective phase II trial

Kerem, Eitan; Hirawat, Samit; Armoni, S.; Yaakov, Yasmin; Shoseyov, David; Cohen, Michael; Nissim-Rafinia, Malka; Blau, Hannah; Rivlin, Joseph; Aviram, Micha; Elfring, Gary L.; Northcutt, Valerie; Miller, Langdon L.; Kerem, Batsheva; Wilschanski, Michael

doi:10.1016/s0140-6736(08)61168-x

Cited by 360 publications

(289 citation statements)

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“…Preclinical studies with gentamicin or PTC124 had succeeded by enhancing stop codon readthrough and were able to be used as therapeutic agents for genetic diseases [9][10][11][12][13][14][15][16][17][18][36][37][38][39][40][41][42]. PTC124 has been successfully extended into clinical trials [18,43], although preliminary results are not clear for Duchenne muscular dystrophy [44]. In the present work, in order to develop future therapeutic approaches we studied the potential drug-mediated readthrough to restore the activity of several lysosomal enzymes in 11 patients affected by 6 different LSDs.…”

Section: Discussionmentioning

confidence: 99%

Effect of Readthrough Treatment in Fibroblasts of Patients Affected by Lysosomal Diseases Caused by Premature Termination Codons

et al. 2015

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Aminoglycoside antibiotics, such as gentamicin, may induce premature termination codon (PTC) readthrough and elude the nonsense-mediated mRNA decay mechanism. Because PTCs are frequently involved in lysosomal diseases, readthrough compounds may be useful as potential therapeutic agents. The aim of our study was to identify patients responsive to gentamicin treatment in order to be used as positive controls to further screen for other PTC readthrough compounds. With this aim, fibroblasts from 11 patients affected by 6 different lysosomal diseases carrying PTCs were treated with gentamicin. Treatment response was evaluated by measuring enzymatic activity, abnormal metabolite accumulation, mRNA expression, protein localization, and cell viability. The potential effect of readthrough was also analyzed by in silico predictions. Results showed that fibroblasts from 5/11 patients exhibited an up to 3-fold increase of enzymatic activity after gentamicin treatment. Accordingly, cell lines tested showed enhanced well-localized protein and/or increased mRNA expression levels and/or reduced metabolite accumulation. Interestingly, these cell lines also showed increased enzymatic activity after PTC124 treatment, which is a PTC readthroughpromoting compound. In conclusion, our results provide a proof-of-concept that PTCs can be effectively suppressed by readthrough drugs, with different efficiencies depending on the genetic context. The screening of new compounds with readthrough activity is a strategy that can be used to develop efficient therapies for diseases caused by PTC mutations.

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Section: Discussionmentioning

confidence: 99%

Effect of Readthrough Treatment in Fibroblasts of Patients Affected by Lysosomal Diseases Caused by Premature Termination Codons

et al. 2015

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“…To date, ataluren has been shown to restore function to more than 20 different disease-specific or reporter nonsense alleles in systems ranging in complexity from in vitro translation to cell culture to mouse models and human patients (1,(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). In the latter, Translarna clinical trials have demonstrated restoration of full-length functional protein in Duchenne muscular dystrophy and cystic fibrosis nonsense mutation patients (10,11,13,15,16). However, a lack of activity has been reported for some cell systems (17,18).…”

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confidence: 99%

Ataluren stimulates ribosomal selection of near-cognate tRNAs to promote nonsense suppression

Roy

Friesen

Tomizawa

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

189

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A premature termination codon (PTC) in the ORF of an mRNA generally leads to production of a truncated polypeptide, accelerated degradation of the mRNA, and depression of overall mRNA expression. Accordingly, nonsense mutations cause some of the most severe forms of inherited disorders. The small-molecule drug ataluren promotes therapeutic nonsense suppression and has been thought to mediate the insertion of near-cognate tRNAs at PTCs. However, direct evidence for this activity has been lacking. Here, we expressed multiple nonsense mutation reporters in human cells and yeast and identified the amino acids inserted when a PTC occupies the ribosomal A site in control, ataluren-treated, and aminoglycoside-treated cells. We find that ataluren’s likely target is the ribosome and that it produces full-length protein by promoting insertion of near-cognate tRNAs at the site of the nonsense codon without apparent effects on transcription, mRNA processing, mRNA stability, or protein stability. The resulting readthrough proteins retain function and contain amino acid replacements similar to those derived from endogenous readthrough, namely Gln, Lys, or Tyr at UAA or UAG PTCs and Trp, Arg, or Cys at UGA PTCs. These insertion biases arise primarily from mRNA:tRNA mispairing at codon positions 1 and 3 and reflect, in part, the preferred use of certain nonstandard base pairs, e.g., U-G. Ataluren’s retention of similar specificity of near-cognate tRNA insertion as occurs endogenously has important implications for its general use in therapeutic nonsense suppression.

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“…This suggests that potential clinical benefit would only need partial restoration of protein function. Phase 2 clinical trials show clear improvement of NPDs [93][94][95], however, a phase 3 clinical trial showed no difference in FEV 1 between the ataluren and placebo group [96] (Table 3). Although the primary outcome was not achieved, the findings are encouraging since it demonstrates a positive effect of disease-modifying therapy using a corrector of CFTR.…”

Section: Future Perspectives a Current Treatment Optionsmentioning

confidence: 99%

CFTR: A new horizon in the pathomechanism and treatment of pancreatitis

Hegyi

2016

Pancreatology

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Cystic fibrosis transmembrane conductance regulator (CFTR) is an ion channel that conducts chloride and bicarbonate ions across epithelial cell membranes. Mutations in the CFTR gene diminish the ion channel function and lead to impaired epithelial fluid transport in multiple organs such as the lung and the pancreas resulting in cystic fibrosis. Heterozygous carriers of CFTR mutations do not develop cystic fibrosis but exhibit increased risk for pancreatitis and associated pancreatic damage characterized by elevated mucus levels, fibrosis and cyst formation. Importantly, recent studies demonstrated that pancreatitis causing insults, such as alcohol, smoking or bile acids strongly inhibit CFTR function. Furthermore, human studies showed reduced levels of CFTR expression and function in all forms of pancreatitis. These findings indicate that impairment of CFTR is critical in the development of pancreatitis; therefore, correcting CFTR function could be the first specific therapy in pancreatitis. In this review, we summarize recent advances in the field and discuss new possibilities for the treatment of pancreatitis.Corresponding author: Prof. Dr. Peter Hegyi, Doctor of the Hungarian Academy of Sciences, First Department of Medicine, University of Szeged, Koranyi fsr. 8-10, SZEGED, H6720, Hungary, TEL: +3662545200, FAX: +3662545185, MOBILE: +36703751031, hegyi.peter@med.u-szeged.hu. Conflict of interest statement: the authors have no conflict of interest to declare HHS Public Access I. Basics of CFTR a. Biosynthesis and degradationThe cystic fibrosis transmembrane conductance regulator (CFTR) protein is a cyclic AMP (cAMP)-regulated chloride (Cl − )/bicarbonate (HCO 3 − ) channel, expressed in the apical plasma membrane (PM) of secretory epithelia in the airways, pancreas, intestine, reproductive organs and exocrine glands [1]. CFTR consists of two homologous halves, each containing a hexa-helical membrane spanning domain (MSD1 and MSD2) and a nucleotide binding domain (NBD1 and NBD2) (Figure 1). The two halves are connected by the R domain [2]. The NBDs contain conserved ATP-binding sequences: Walker A and B motifs, classifying CFTR as a member of the ATP-binding cassette (ABC) transporter family. Structural, biochemical and functional evidence suggest that the two NBD domains interact and the ATP-binding site of one NBD is complemented by the ABC signature motif of the other [2].While NBD1 folds largely co-translationally, the native fold of NBD2 as well as CFTR are attained post-translationally [3]. Assembly of MSD1, NBD1, R domain and MSD2 is necessary and sufficient to form the minimal folding unit of CFTR [4]. These and other observations support the cooperative domain folding model and ensure the dynamic conformational coupling between the cytosolic NBDs and the pore-forming MSDs in the native molecule and provide a structural explanation for the cooperative domain unfolding, caused by cystic fibrosis (CF) mutations [4].Despite interactions with several cytosolic and endoplasmic reticulum (ER) chapero...

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Effectiveness of PTC124 treatment of cystic fibrosis caused by nonsense mutations: a prospective phase II trial

Cited by 360 publications

References 32 publications

Effect of Readthrough Treatment in Fibroblasts of Patients Affected by Lysosomal Diseases Caused by Premature Termination Codons

Effect of Readthrough Treatment in Fibroblasts of Patients Affected by Lysosomal Diseases Caused by Premature Termination Codons

Ataluren stimulates ribosomal selection of near-cognate tRNAs to promote nonsense suppression

CFTR: A new horizon in the pathomechanism and treatment of pancreatitis

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