Crystalys Doses First Patients in Europe for Phase 3 Dotinurad Gout Trial

Crystalys Doses First Patients in Europe for Phase 3 Dotinurad Gout Trial

By, Admin 3 February 2026

Crystalys Therapeutics has announced that the first patients have been dosed at European clinical sites in its Phase 3 RUBY study evaluating dotinurad.

Dotinurad is a next-generation, once-daily oral URAT1 inhibitor being developed for the treatment of hyperuricemia associated with gout.

The RUBY study is part of Crystalys’ global Phase 3 program supporting dotinurad as a potential second-line therapy for patients who do not respond adequately to allopurinol.

Why This Milestone Matters?

Expanding dosing into Europe marks an important step toward global development of dotinurad.

It also reflects continued progress in building enrollment across multiple regions.

James Mackay, Ph.D., President and CEO of Crystalys Therapeutics, said the company views European activation as a key milestone for the RUBY study.

Inside the Phase 3 RUBY Study

The RUBY study (NCT07089875) is:

  • Phase 3, randomized, double-blind, multicenter
  • Enrolling approximately 500 patients
  • Evaluating safety and efficacy of dotinurad
  • Once-daily oral dosing for up to 64 weeks

The study is designed to support regulatory submissions in major markets.

The Unmet Need in Gout Treatment

Gout is the most common form of inflammatory arthritis. It is caused by excess uric acid in the blood, known as hyperuricemia. This leads to crystal formation, inflammation, and severe joint pain.

Key treatment challenges today include:

  • Many patients fail first-line xanthine oxidase inhibitors (XOIs)
  • Uricase therapies are reserved as last-line options
  • No widely available second-line oral therapies exist in the U.S. or EU

This leaves a large population without effective long-term control.

About Dotinurad

Dotinurad is a selective URAT1 inhibitor designed to:

  • Lower serum uric acid
  • Reduce gout flares
  • Decrease tophi formation

The drug was invented by Fuji Yakuhin. It is already approved in:

  • Japan
  • China

Philippines

  • Thailand

Clinical data from these markets support its safety and efficacy profile.

About Crystalys Therapeutics

Crystalys Therapeutics is a clinical-stage biopharmaceutical company focused on transforming gout treatment. The company is headquartered in San Diego, California.

It was co-founded by Catalys Pacific and Novo Holdings. Crystalys is advancing dotinurad through global Phase 3 trials toward regulatory approval and commercialization.

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