Orthogonal Analysis of Dystrophin Protein and Mrna As A Surrogate Outcome for Drug Development

Abstract

<b>Aim:</b> Detection of drug-induced dystrophin in patient muscle biopsy is a surrogate outcome measure for Duchenne muscular dystrophy. We sought to establish and validate an orthogonal approach to measurement of dystrophin protein and RNA in muscle biopsies. <b>Materials & methods:</b> Validated methods were developed for dystrophin western blotting, mass spectrometry, immunostaining and reverse transcriptase PCR of biopsy mRNA using muscle biopsy standards. <b>Results:</b> Both western blotting and mass spectrometry validated methods demonstrated good linearity, and acceptable precision and accuracy with a lower limit of quantitation at 1%. Immunostaining and reverse transcriptase PCR methods were shown to be reliable. <b>Conclusion:</b> The described orthogonal approach is sufficient to support measures of dystrophin as a surrogate outcome in a clinical trial.