A Phase 3 interventional study of Allopurinol and Dotinurad in Tophaceous Gout, sponsored by Crystalys Therapeutics. Recruiting at 96 sites in United States. Open to participants aged 18 Years to 75 Years. Per ClinicalTrials.gov, last updated 2026-10-29.
Sponsored by Crystalys Therapeutics · Phase 3, Interventional, and Treatment
The primary objective of this study is to evaluate the efficacy of dotinurad in lowering serum uric acid (sUA) at Week 24 compared with allopurinol in adult participants with tophaceous gout.
240 studies on the registry are indexed under Hyperuricemia; 44 are open to participants now.
This study's planned enrollment of 250 is above the median of 68 across 193 interventional studies indexed under Hyperuricemia.
Browse Hyperuricemia studies →Crystalys Therapeutics is the lead sponsor of 3 studies on the registry; 3 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will discontinue their allopurinol and start on study-supplied allopurinol at the same dose once a day (QD) through Week 76.
Drug: Allopurinol
Participants will discontinue their allopurinol and start dotinurad 1 mg QD for first 4 weeks (Weeks 1-4), dotinurad 2 mg QD for the next 8 weeks (Weeks 5-12), and dotinurad 4 mg QD thereafter up through Week 76.
Drug: Dotinurad
Over-encapsulated tablets containing active drug substance administered orally (PO).
Over-encapsulated tablets containing active drug substance administered PO.
Percentage of Participants with an sUA Level <5.0 mg/dL at Week 24
Time frame: Week 24
Percentage of Participants who Experience Complete Response (CR) or Partial Response (PR) of ≥1 Target Tophus at Week 76
Time frame: Week 76
Percentage of Participants who Experience CR of ≥1 Target Tophus at Week 76
Time frame: Week 76
Percentage of Participants with an sUA Level <4.0 mg/dL at Week 24
Time frame: Week 24
Mean Rate of Gout Flares Requiring Treatment from Week 36 Through Week 76
Time frame: Week 36 through Week 76
Percentage of Participants with an sUA Level <5.0 mg/dL at Week 24 and No Gout Flares Requiring Treatment from Week 36 Through Week 76
Time frame: Week 24 and Week 36 through Week 76
Mean Change from Baseline in sUA at Week 24
Time frame: Baseline and Week 24
Mean Percent Change from Baseline in the Sum of the Areas for all Target Tophi at Each Visit
Time frame: Baseline to Week 80
Percentage of Participants who Do Not have a Gout Flare Requiring Treatment from Week 36 through Week 76
Time frame: Week 36 through Week 76
Percentage of Participants with an sUA Level <5.0 mg/dL at Each Visit
Time frame: Up to Week 80
Percentage of Participants with an sUA Level <4.0 mg/dL at Each Visit
Time frame: Up to Week 80
Percentage of Participants with an sUA Level <3.0 mg/dL at Each Visit
Time frame: Up to Week 80
Absolute Change from Baseline in sUA Levels at Each Visit
Time frame: Baseline to Week 80
Percent Change from Baseline in sUA Levels at Each Visit
Time frame: Baseline to Week 80
Percentage of Participants with a Gout Flare Requiring Treatment at Each Month Between Week 24 and the End of Study
Time frame: Week 24 to Week 80
Percentage of Participants with Treatment-emergent Adverse Events (TEAEs)
Time frame: Up to Week 80
Percentage of Participants with Serious Adverse Events (SAEs)
Time frame: Up to Week 80
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Plan to share: Yes — Individual participant data that underlie the results reported for publication, after deidentification.
Supporting information: Study protocol, Statistical analysis plan
Started Aug 2025 (actual). Primary completion is estimated for Dec 2027, 28 months after the start.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
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Studies of the drug tested here: Dotinurad