Abcuro raised $66 million in a Series D to advance ulviprubart for inclusion body myositis (IBM), a progressive muscle disorder with no FDA-approved therapies. The company said the funding will support a registrational clinical study, with preparations for a trial kickoff targeted for the fourth quarter of 2026. Abcuro’s ulviprubart is designed as a monoclonal antibody intended to selectively deplete cytotoxic T cells implicated in IBM muscle damage while preserving broader immune function. The company referenced encouraging signals from its Phase II/III MUSCLE study (NCT05721573), noting the overall population did not meet the primary endpoint but a pre-specified subgroup showed a compelling trend. The Series D was led by New Leaf Venture Partners with participation from other life sciences investors, underscoring continued venture support for rare-disease immunology assets that can translate into registrational pathways.