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Phase 1b Trial of RAY121 for Immunological Diseases

This study is testing a new drug called RAY121 for safety and how well it's tolerated in people with certain immunological diseases. These include Antiphospholipid Syndrome (APS), Bullous Pemphigoid (BP), Behçet's Syndrome (BS), Dermatomyositis (DM), and Immune-mediated Necrotizing Myopathy (IMNM). RAY121 works by blocking a part of your immune system called the classical complement pathway. The main goal is to see if RAY121 causes any side effects. We are looking for about 144 participants aged 18 to 85. The current status of this study is unclear.

Study design
This is a Phase 1b study, which means it's an early-stage trial looking at safety. It aims to enroll 144 participants.
What's involved
Not specified in the trial record.
Compensation
Not stated in the trial record.
Follow-up
Adverse events (side effects) will be monitored from the start of the study until Week 32.

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

NCT06371417

Phase 1b Trial of RAY121 in Immunological Diseases (RAINBOW Trial)

Recruiting
PHASE1Ages 18–85InterventionalTreatment
Chugai Pharmaceutical
~144 participants
Updated 2026-07-22 on ClinicalTrials.gov
What's tested:RAY121

At a glance

Recruiting sites
48 of 77 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Adverse events (AEs)
Measured over Baseline to Week 32

Conditions

Antiphospholipid Syndrome (APS)
Bullous Pemphigoid (BP)
Behçet's Syndrome (BS)
Dermatomyositis (DM)
Immune-mediated Necrotizing Myopathy (IMNM)
Immune Thrombocytopenia (ITP)

Explore related trials

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Where it's being run

77 sites across 58 states
Texas3
New South Wales3
Sofia City Province3
Quebec3
Tokyo3
New York2
Victoria2
Alberta2

Study leadership

Who to contact

Clinical trials information
[email protected]
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Do you actually qualify for this trial?

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Eligibility criteria

Exclusion

1\) APS associated with other systemic autoimmune disease
2\) Acute thrombosis (arterial or venous acute thrombosis diagnosis) within 30 days before screening
3\) Patients with thrombotic APS without any anticoagulation treatment
4\) Treatment with prohibited medications 20. BP cohort:
2\) Current treatment with a drug that may cause or exacerbate BP unless the dose has been stable
3\) Initiation of treatment with topical calcineurin inhibitor, or topical phosphodiesterase (PDE) 4 inhibitor within 7 days
4\) Treatment with prohibited medications 21. BS cohort:
2\) History of venous or arterial thrombosis within 1 year
3\) Treatment with prohibited medications 22. DM cohort:
2\) Overlap myositis (except for overlap with Sjögren's syndrome), connective tissue disease associated DM, inclusion body myositis, polymyositis, IMNM, juvenile DM or drug-induced myopathy
3\) Cancer-associated myositis
4\) Significant muscle damage
5\) Past history of severe Interstitial lung disease flare, severe non-infectious lung inflammation which required active intervention, or multiple episodes of lung disease
6\) Severe respiratory muscle weakness
7\) Severe bulbar palsy
8\) Treatment with prohibited medications 23. IMNM cohort:
5\) Treatment with prohibited medications
6\) Any laboratory test results meet either of the following criteria at screening:
Hemoglobin \<10 g/dL
Thyroid-stimulating hormone \>= 10 μIU/mL

What this trial measures

  • Adverse events (AEs)Baseline to Week 32

    Incidence, severity, and causal relationship of AEs