NCT06913907

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)

• Status: Recruiting
• Phase: Phase 4
• Study type: Interventional
• Enrollment: 100 (estimated)
• Sponsor: Keio University · Academic / Other
• Sex: All
• Age: 18 Years
• Healthy volunteers: Not accepted

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.

Conditions

• Rheumatoid Arthritis (RA)

Interventions

Type	Name	Description
DRUG	Methotrexate (MTX)	Single arm study

Timeline

• Start date: 2025-04-10
• Primary completion: 2027-12-31
• Completion: 2027-12-31
• First posted: 2025-04-06
• Last updated: 2025-04-06

Locations

1 site across 1 country: Japan