Crystalys raises $130m Series B for gout drug dotinurad

Crystalys Therapeutics has closed an oversubscribed $130 million Series B to advance dotinurad, its once-daily oral URAT1 inhibitor, through late-stage clinical development and into commercial readiness in the United States and Europe. The round was announced on 27 July 2026 via parent-company filings from Fortress Biotech, whose subsidiary Urica Therapeutics holds a minority equity stake in Crystalys and is eligible for a 3% royalty on future net sales of dotinurad.

Urica originally developed dotinurad before selling the asset to Crystalys in 2024, retaining the royalty stream and equity position that makes this financing directly material to Fortress shareholders.

The clinical programme

Dotinurad is currently being evaluated across three concurrent studies. The Phase 3 RUBY and TOPAZ trials are registration-directed, designed to generate the pivotal efficacy and safety data required for regulatory submissions in the US and Europe. A Phase 2 study, AMETHYST, is running in parallel to assess the drug in broader patient populations, including those with limited existing treatment options such as patients with renal impairment, for whom current urate-lowering therapies can be problematic.

Lindsay Rosenwald, executive chairman, president and chief executive of Fortress, said the financing "paves the way toward regulatory approval and commercialisation for dotinurad in the United States and Europe, potentially bringing a new treatment option to the millions of people living with gout." Rosenwald also highlighted that the transaction strengthens Fortress's position through Urica's equity stake and royalty entitlement.

The company said proceeds will cover ongoing trial costs, commercial preparation activities, and operational runway through multiple anticipated clinical and regulatory milestones, though it did not specify a timeline for NDA or MAA submissions.

Market context and competitive landscape

Gout is among the most prevalent inflammatory arthropathies globally, affecting an estimated 40 million people worldwide, and the urate-lowering therapy market is well established but imperfect. Allopurinol and febuxostat dominate prescribing, but tolerability and contraindications leave a meaningful unmet need, particularly in patients with moderate-to-severe chronic kidney disease. URAT1 inhibition as a mechanism is not new, lesinurad (Zurampic) was approved in the US in 2015 but was withdrawn from the market in 2019 on commercial grounds rather than safety concerns, a precedent that will invite scrutiny of dotinurad's differentiation story.

Dotinurad is already approved in Japan, where it is marketed as Urece by Fuji Yakuhin, providing real-world tolerability data that Crystalys and Urica will likely reference in their regulatory filings. That prior approval gives the asset a degree of de-risking that is uncommon at the Phase 3 stage, and is a factor investors in this round will have weighed carefully.

The competitive window also includes pegloticase-based combination regimens and emerging oral agents in development at smaller biotechs. Crystalys's ability to secure $130 million in an oversubscribed round suggests investors view the Japanese dataset, the broad Phase 3 programme, and the royalty-backed corporate structure as a credible path to approval. How the RUBY and TOPAZ readouts compare to existing benchmarks for serum urate reduction and flare frequency will determine whether that confidence is borne out.