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Natrunix

Phase 2

Rheumatoid Arthritis | Small molecule | Immunology |XBiotech Inc.|Last Updated: Dec 9, 2025

Success Probability
Approval Probability 71%
TA Base Rate26%
Adjusted LOA41%
ML RiskLOW_RISK
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Market & Valuation
rNPV $3.2B
Market Size $9.4B
Revenue Basis $1.6B
Competitors 6
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Trial Design
RandomizedDouble-BlindPLACEBO_CONTROLLEDBiomarker
Total Trials2
Total Enrollment351
FDA Designations
No designations recorded
Clinical Trials (2)
NCT IDTitlePhaseStatusEnrollmentVelocityDesignStartCompletionLast UpdatedSitesCountries
NCT06590090Natrunix in Combination With Methotrexate for Rheumatoid Arthritis TreatmentPHASE2 NOT YET_RECRUITING 108Jul 15, 2026Jul 15, 2027Dec 9, 2025 -
NCT05363891Natrunix or Placebo in Combination With Methotrexate in Rheumatoid ArthritisPHASE2 COMPLETED 243Aug 8, 2023Oct 31, 2024Jan 16, 202526 United States
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Study Endpoints
Primary Endpoints
ACR 20 response
at 14 weeks from baseline

The American College of Rheumatology (ACR) response criteria for rheumatoid arthritis (RA) are used to measure how effective study drug is in this study.

ACR 20 response rate at 12 weeks.
At 12 weeks from baseline

The ACR is a measure used in clinical practice and clinical trial to assess medication efficacy in patients with RA, by notating improvements in swelling and tenderness in designated joints, as well as improvements in at least 3 out of 5 other categories. The other categories assessed are patient global assessment of disease activity, physician global assessment of disease activity, patient reported pain scale, disability/functionality questionnaire response, and acute phase reactant levels (CRP and ESR).

Secondary Endpoints
ACR 50 response rate
at 14 weeks from baseline
Mean change in number of swollen and tender joints based on 66/68-joint count
at 14 weeks from baseline
Mean change in NRS-pain score
at 14 weeks from baseline
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Study Design & Arms
AllocationRANDOMIZED
MaskingTRIPLE
ModelPARALLEL
PurposeTREATMENT
Treatment Arms
ArmTypeDescription
400mg Natrunix + MTX weeklyEXPERIMENTALSubjects will receive 400mg Natrunix and MTX weekly
Placebo+ MTX weeklyEXPERIMENTALSubjects will receive placebo and MTX weekly
Natrunix 200mg with MTX(+Folate)EXPERIMENTALNatrunix 200mg, subcutaneous injection in combination with Methotrexate (+Folate).This arm will enroll 70 subjects.
Natrunix 400mg with MTX(+Folate)EXPERIMENTALNatrunix 400mg, subcutaneous injection in combination with Methotrexate (+Folate).This arm will enroll 70 subjects.
Placebo with MTX(+Folate)PLACEBO_COMPARATORPlacebo in combination with Methotrexate (+Folate).This arm will enroll 70 subjects.
Interventions
NameTypeDescription
Natrunix 400 mgBIOLOGICALThe active ingredient of Natrunix is an IgG4 monoclonal antibody indistinguishable from that naturally occurring in an IL-1a-immune healthy human. Natrunix is formulated as 200 mg/mL sterile liquid in a stabilizing isotonic formulation buffered to pH 7.0. The product is filled into a 2 mL glass pre-filled syringe suitable for subcutaneous injection. The drug product is formulated and buffered to a neutral body pH of 7.0.
PlaceboDRUGPlacebo is a sterile liquid solution filled into a 2 mL glass pre-filled syringe, suitable for subcutaneous injection, containing the exact same buffer matrix used for Natrunix drug product
Methotrexate (MTX)DRUGMethotrexate may be administered in pill form by mouth, as liquid by mouth, or by subcutaneous injection.Subjects enrolled in this study should be receiving a stable minimum weekly dose of 10mg. Weekly methotrexate should not exceed 25 mg/week.
NatrunixDRUGNatrunix is a unique kind of drug-an immunoglobulin cloned from a naturally occurring immune response from a healthy human donor. Natrunix blocks inflammation in a unique way-it is the only therapeutic that exclusively neutralizes interleukin-1α (IL-1α), a crucial mediator of interleukin-1 inflammation. Targeting IL-1α directly using a natural human monoclonal antibody may provide a safer and more effective means of blocking interleukin-1 in rheumatoid arthritis.
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Eligibility Criteria
Age Range18 Years — N/A
SexALL
Healthy VolunteersNo

Inclusion Criteria: 1. Weight \> 40 kg 2. Diagnosis of moderate to severe RA according to 2010 ACR/EULAR classification criteria. 3. Patients must be methotrexate-inadequate responders. a. Persistent moderate to severe RA disease activity (i.e., criteria #2 above) despite ongoing treatment with...

Countries:United States
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Recent Changes (Last 90 Days)
LOWMay 26, 2026NCT06590090primaryCompletionDate: changed
LOWMay 24, 2026NCT06590090studyFirstPostDate: changed