Ataluren (PTC124)

Cftr-/- hCFTR-G542X transgenic mice

A Phase III study of PTC124 for previously treated patients with nonsense mutation dystrophinopathy (nmDBMD) in Europe, Israel, Australia, and Canada is currently ongoing.

ca.60 mg/kg/day

Dissolved in DMSO, and diluted in saline

Compared with Gentamicin which is only active at much higher concentrations, 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 uM) 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. Like Gentamicin, 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 uM) 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]

Assays for read-through of LUC premature termination codons, Stock solutions of PTC124 (6 mM) are prepared in 100% DMSO HEK293 cells grown in a medium containing fetal bovine serum (FBS) and are stably transfected with LUC genes containing premature terminators at codon 190 (and 11 contextual variants thereof), treated with increasing concentrations of PTC124 for 16 hours, and assayed for luciferase activity. Luminescence of each culture relative to the control is quantified by standard procedures using a Viewlux CCD imager. Luminescence data are normalized to that produced with DMSO, and the fold suppression over background is calculated as (PTC124light units/DMSOlight units).

PTC124 (Ataluren) Chemical Structure

DMSO 57 mg/mL, Water <1 mg/mL, Ethanol <1 mg/mL