Mirum Pharmaceuticals announced U.S. FDA approval of its once-daily oral ALK2 inhibitor Atebrioz (zilurgisertib) for fibrodysplasia ossificans progressiva and followed with positive Phase 3 results for brelovitug in chronic hepatitis delta virus (HDV). The HDV win further strengthens Mirum’s plan to build a commercial franchise in an HDV market where Gilead dominates treated populations. For brelovitug, the company reported that the trial met its primary endpoint assessing virologic response and ALT normalization, and said updated peak sales guidance now targets a potential $1 billion, contingent on later confirmation. Mirum expects to file a BLA in 2027 pending results from a second pivotal study. The combination of regulatory approval for Atebrioz and HDV clinical momentum highlights how Mirum is aiming to diversify revenue streams while sustaining pipeline optionality. Commercial differentiation may hinge on dosing convenience for Atebrioz and on durability, response depth, and retreatment considerations for brelovitug. Investors also appear to view Mirum’s HDV data as meaningful timing for pipeline conversion given the competitive pressure in HDV and the scrutiny regulators bring to confirmatory evidence.