Recruiting
Phase 2

THB335-201

Sponsor:

Calixis Inc.

Code:

NCT07766499

Conditions

Chronic Spontaneous Urticaria (CSU)

Chronic Idiopathic Urticaria

Eligibility Criteria

Sex: All

Age: 18 - 70+

Healthy Volunteers: Not accepted

Interventions

THB335 Lower Dose

THB335 Higher Dose

Placebo

Study Details

Brief summary:

THB335-201 is a Phase 2, randomized, double-blind, placebo-controlled, parallel-group, multicenter study in adults with CSU who remain symptomatic despite standard-of-care treatment. The study includes a Screening Period of up to 4 weeks, a 12-week Treatment Period, and a 4-week Follow-Up Period, for a total participant duration of approximately 20 weeks.

Conditions

Chronic Spontaneous Urticaria (CSU)

Chronic Idiopathic Urticaria

Study ID

NCT07766499

Start date

Sep 15, 2026

Status verified date

Oct, 2026

Completion date

Jan 31, 2028

Anticipated

Primary completion date

Dec 31, 2027

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18 - 70+

Healthy Volunteers: Not accepted

Key Inclusion Criteria:

  • Males and females 18 through 85 years.
  • Diagnosis of chronic spontaneous urticaria (CSU) ≥ 6 months.
  • Active CSU despite treatment with a second-generation H1 antihistamine.
  • Weekly Urticaria Activity Score (UAS7) ≥ 16 and ISS7 ≥ 8 during the 7 days before randomization, with sufficient electronic diary entries to calculate the baseline scores.
  • Body mass index of 18 to 38 kg/m² and minimum body weight of 50 kg for male participants or 45 kg for female participants.
  • Willing and able to complete the daily electronic diary, attend scheduled study visits, and comply with study procedures.
  • Participants capable of becoming pregnant or producing sperm must agree to follow the protocol-defined contraception requirements.

Key Exclusion Criteria:

  • Chronic urticaria with an identified cause other than chronic spontaneous urticaria.
  • Another active skin condition associated with chronic itching that could interfere with the study assessments.
  • Recent treatment with prohibited immunosuppressive therapy, biologic therapy, a Bruton's tyrosine kinase inhibitor, an investigational drug, or another therapy that inhibits the c-KIT receptor.
  • Clinically significant hepatic, hematologic, or renal disease or laboratory abnormalities.
  • Active, chronic, or recurrent infection, including human immunodeficiency virus or viral hepatitis infection.
  • Clinically significant cardiovascular disease or electrocardiogram abnormality, including clinically significant arrhythmia, prolonged QT interval, familial long QT syndrome, or use of medication known to prolong the QT interval that cannot be discontinued.
  • History of idiopathic anaphylaxis, a severe allergic reaction that may increase the risk of study participation, or hypersensitivity to the study drug or related compounds.
  • History of malignancy within the previous 5 years, except successfully treated nonmetastatic basal cell or squamous cell skin cancer or carcinoma in situ.
  • Current or planned use of prohibited medications, including specified inhibitors, inducers, or sensitive substrates of drug-metabolizing enzymes or transporters, or proton pump inhibitors.
  • Positive urine drug screen at Screening.
  • Pregnancy or breastfeeding.
  • Any medical or psychiatric condition that, in the investigator's judgment, could place the participant at increased risk, interfere with the study assessments, or affect the participant's ability to complete the study.

Additional eligibility criteria are outlined in the full protocol. The study investigator will review all requirements with potential participants to determine whether they are eligible to participate.

Study Design

Enrollment

81 participants

Anticipated

Allocation

Randomized

Intervention Model

Parallel Assignment

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

experimental: THB335 Higher Dose

Orally-administered THB335 higher dose.

experimental: THB335 Lower Dose

Orally-administered THB335 lower dose.

placebo comparator: Placebo

Orally-administered matching placebo.

Interventions

THB335 Lower Dose

THB335 is an orally administered capsule added to a stable background regimen of a second generation H1 antihistamine.

THB335 Higher Dose

THB335 is an orally administered capsule added to a stable background regimen of a second generation H1 antihistamine.

Placebo

Placebo is an orally administered capsule added to a stable background regimen of a second generation H1 antihistamine.

Primary outcome measure

  • Change From Baseline in Weekly Urticaria Activity Score (UAS7) at Week 12 [ Time Frame: Baseline and Week 12 ]

Central Contacts and Locations

Central contacts

Clinical Trials Monitor

+1 (617) 299 - 6702info@calixisbio.com

Locations

Calixis Study Site

Recruiting

Pasadena, California, United States, 91106

Calixis Study Site

Recruiting

Ventura, California, United States, 93003

Calixis Study Site

Recruiting

Walnut Creek, California, United States, 94596

Calixis Study Site

Recruiting

Altamonte Springs, Florida, United States, 32701

Calixis Study Site

Recruiting

Tampa, Florida, United States, 33607

Calixis Study Site

Recruiting

Atlanta, Georgia, United States, 30329

Calixis Study Site

Recruiting

Boise, Idaho, United States, 83706

Calixis Study Site

Recruiting

Baton Rouge, Louisiana, United States, 70809

Calixis Study Site

Recruiting

White Marsh, Maryland, United States, 21162

Calixis Study Site

Recruiting

Wildwood, Missouri, United States, 63040

Calixis Study Site

Recruiting

Asheville, North Carolina, United States, 28803

Calixis Study Site

Recruiting

Smyrna, Tennessee, United States, 37167

Calixis Study Site

Recruiting

Austin, Texas, United States, 78726

Calixis Study Site

Recruiting

Houston, Texas, United States, 77082

Calixis Study Site

Recruiting

Prosper, Texas, United States, 75078

More Information

Sponsor

Calixis Inc.

Last update posted

Nov 2, 2026

Last verified

Oct, 2026

Keywords

  • Chronic spontaneous urticaria
  • CSU
  • Chronic hives
  • THB335
  • Second-generation H1 antihistamine
  • Urticaria Activity Score 7
  • UAS7
  • Chronic urticaria
  • Urticaria
  • Histamine H1 Antagonists

Trial information was received from ClinicalTrials.gov and was last updated on 2026-11-03. This information was provided to ClinicalTrials.gov by Calixis Inc. on 2026-11-02. Recruitment status is synced daily from ClinicalTrials.gov and may not reflect the sponsor's current status. Confirm during your call.