Ataluren (PTC124)

PTC124 is a more potent nonsense-suppressing agent and exhibits 4- to 15-fold stimulation of read-through relative to controls. PTC124 (0.01-3 μM) promotes dose-dependent read-through of all three nonsense codons in HEK293 cells harboring LUC-190 nonsense alleles with the highest read-through at UGA, followed by UAG and then UAA, but it does not suppress multiple proximal nonsense codons. PTC124 is most active when a pyrimidine (in particular cytosine, C) follows the nonsense codon. Consistent with the stable cell line reporter assay, PTC124 (17 μM) promotes significant production of dystrophin in primary muscle cells from Duchenne muscular dystrophy (DMD) patients or MDXMDX mice expressing dystrophin nonsense alleles. PTC124 selectively promotes ribosomal read-through of premature termination but not normal termination codons, even at concentrations substantially greater than the values achieving maximal activity. ^[1]

Due to functional recovery of dystrophin production, oral, intraperitoneal or combined dosing of PTC124 for 2-8 weeks partially rescues functional strength deficit in dystrophic muscles of MDX mice, and results in partial protection against contraction-induced injury in the extensor digitorum longus (EDL) muscles, as well as significant reductions in serum creatine kinase values. ^[1] In Cftr-/- mice expressing a human CFTR-G542X transgene, subcutaneous or oral administration of PTC124 (~60 mg/kg) suppresses the G542X nonsense mutation in a dose-dependent manner, leading to a significant restoration of human (h)CFTR protein expression and function without any effect on nonsense-mediated mRNA decay (NMD) or other aspects of mRNA stability. PTC124 treatment (60 mg/kg) restores 29% of the normal intestinal transepithelial cAMP-stimulated shortcircuit currents observed in Cftr+/+ mice, displaying a significant advantage. ^[2]

• Animal Models

  Cftr-/- hCFTR-G542X transgenic mice

• Dosages

  ~60 mg/kg/day

• Administration

  Subcutaneous injection or oral administration