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Controversy over Sarepta’s first agent, Exondys 51, erupted when the exon-skipping phosphorodiamidate morpholino oligonucleotide antisense drug received the go-ahead following intense pressure from the patient community. Critics contended that FDA leadership ignored the advice from internal reviewers who felt the efficacy data were unconvincing, two of whom resigned over the approval. Moreover, the approval was conditional on the company agreeing to conduct a two-year post-approval trial to show Exondys 51’s efficacy. But by August 2019, the company had yet to begin such a trial and in the meantime had profited from sales of $300 million in 2018.