RecruitingPhase 4NCT06913907

Changes in MTX-PG Concentrations During Subcutaneous MTX Therapy in Patients With Rheumatoid Arthritis(COSMOS Study)

Changes in Methotrexate Polyglutamate Concentrations When Changing From Oral to Subcutaneous Methotrexate Therapy in Methotrexate-naive Patients With Rheumatoid Arthritis: (COSMOS Study)

Sponsor

Keio University

Enrollment

100 participants

Start Date

Apr 10, 2025

Study Type

INTERVENTIONAL

Conditions

Rheumatoid Arthritis (RA)

Summary

Methotrexate is known to exist intracellularly as methotrexate polyglutamate, which is formed by the addition of glutamic acid after absorption into the body. The objective of this study is to measure the concentration of methotrexate polyglutamate in red blood cells and peripheral blood mononuclear cells after initiating methotrexate treatment in patients with rheumatoid arthritis who have no prior history of using methotrexate (either subcutaneous or oral formulations). Additionally, we aim to examine changes in methotrexate polyglutamate concentrations when switching from oral methotrexate to subcutaneous Metoject, as well as to investigate the relationship between methotrexate polyglutamate concentration and the efficacy and safety of the treatment. Another objective of this study is to evaluate whether switching to subcutaneous Metoject allows for an increased maximum tolerable dosage while maintaining safety.

Eligibility

Min Age: 18 Years

Plain Language Summary

Simplified for easier understanding

This study is tracking how levels of a drug called methotrexate (MTX) — measured inside red blood cells — change over time in patients with rheumatoid arthritis who are starting subcutaneous (under-the-skin injection) methotrexate therapy. **You may be eligible if...** - You are 18 or older - You have been diagnosed with rheumatoid arthritis (meeting 2010 criteria) - Your disease is active (SDAI score above 11) - You have not previously taken methotrexate or biologic/JAK inhibitor treatments - You can use effective contraception if of childbearing potential **You may NOT be eligible if...** - You are pregnant or may be pregnant - You have significant liver disease, cirrhosis, or elevated liver enzymes (above 150 U/L) - You have severe kidney problems or are on dialysis - You have a blood disorder such as aplastic anemia or a recent lymphoproliferative disease - You have active tuberculosis or pleural/abdominal fluid buildup Talk to your doctor to see if this trial is right for you.

This summary was AI-generated to explain the trial in plain language. It is not medical advice. Always discuss eligibility with your doctor before enrolling in a clinical trial.

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