The FDA has accepted the now third NDA submission from Stealth BioTherapeutics, for elamipretide in Barth Syndrome (rare, genetic disorder). I have put together a timeline below of the very tortuous history between Stealth and the FDA. • Dec ’16 - Stealth submits a protocol to the FDA to evaluate elamipretide in patients with Barth syndrome. • Nov ’17 - FDA grants Fast Track designation. • Mar ’18 - FDA grants Orphan Drug designation. • Jan ’19 - Stealth meets with the FDA, indicating its intent to submit an NDA. • Mar ’20 - FDA grants Rare Pediatric Disease designation. • Jan ’19 to May ’21 - Several meetings with the FDA. FDA states existing data is unlikely to support filing and recommends a new phase 3 trial. • Aug ’21 - Stealth submits an NDA for Barth syndrome despite prior FDA feedback. • Oct ’21 - FDA issues refuse-to-file letter • Nov ’21 - Stealth and the FDA discuss the refuse-to-file letter. FDA continue to recommend a new phase 3 trial. Stealth informs the FDA of their intent to resubmit the NDA without conducting a new trial. • Aug ’22 - Stealth takes company private. • Dec ’23 - The Barth Syndrome Foundation submits a petition to the FDA advocating for a fair, equitable and appropriate review. • Jan ’24 - Stealth resubmits the NDA. • Mar ’24 - FDA accepts the NDA (Standard Review) to conduct a more detailed review of the data and plans to convene an advisory committee for external input. • Apr ’24 - FDA upgrades the review to Priority Review. • Oct ’24 - The Cardiovascular and Renal Drugs Advisory Committee votes 10–6 that elamipretide is effective for treating patients with Barth syndrome. • Jan ’25 - Following the AdCom, the FDA requests additional data constituting a major amendment. The PDUFA date is extended by three months. • Apr ’25 - FDA misses the PDUFA date. • May ’25 - FDA issues a Complete Response Letter. Stealth cuts its workforce by ~30%. • May ’25 - FDA responds to Dec ’23 petition. • 18 Aug ’25 - Stealth resubmits the NDA following feedback from the FDA, seeking accelerated approval based on an intermediate clinical endpoint, using data already included in prior submissions. • 21 Aug ’25 - FDA accepts the resubmission with goal date of 26 September 2025.