OMass Therapeutics closed an oversubscribed $310 million Series C to advance its lead ACTH-pathway inhibitor OMS1620 into Phase II for congenital adrenal hyperplasia (CAH) and ACTH-dependent Cushing’s syndrome. The company also earmarked funding for earlier clinical work on SLC15A4, targeting interferon-linked conditions including lupus. The round is co-led by Bain Capital Life Sciences, Forbion, and Novo Holdings, with additional participation from Janus Henderson, SV Health Investors, and Jefferson Life Sciences, alongside existing backers including Syncona and Sanofi Ventures. Proceeds will support the next phase of clinical execution and pipeline development. In parallel, the financing highlights continued appetite for endocrine rare diseases where mechanistic biology can be translated into patient-selective pharmacology, and where biomarker-driven patient stratification remains a key strategic lever. The company framed the capital raise as a way to generate “meaningful data” across two programs rather than a single-asset bet, positioning OMS for follow-on milestones as it builds clinical evidence for receptor residency and interferon-pathway modulation.