PTC Therapeutics, Inc. announced that the U.S. FDA has issued a Complete Response Letter (CRL) related to the New Drug Application (NDA) for vatiquinone for the treatment of children and adults living with Friedreich’s ataxia.The FDA stated in the CRL that substantial evidence of efficacy was not demonstrated for vatiquinone and that an additional adequate and well-controlled study would be needed to support NDA resubmission.“We are of course disappointed by the FDA’s decision ...