C1M Biomarker May Predict Joint Damage in Early Arthritis

TOPLINE:

Higher baseline serum levels of C1M, a biochemical marker of type I collagen degradation, were associated with higher odds of progression of total joint damage in patients with early arthritis at 1 and 5 years; however, the C2M marker showed no association with progression.

METHODOLOGY:

• Researchers investigated the association between baseline serum C1M and C2M levels and the radiographic progression of joint damage in a cohort of patients with early undifferentiated inflammatory arthritis and recently developed rheumatoid arthritis (the ESPOIR cohort).
• They included 813 patients (mean age, 48.1 years; 76% women) having two or more swollen joints, with the swelling lasting more than 6 weeks but less than 6 months, and no previous use of disease-modifying drugs or steroids.
• Radiographs of the hands, wrists, and feet were obtained and scored according to the van der Heijde-modified Sharp score (mSS), assessing erosion, joint space narrowing, and total radiographic scores for each patient; serum C1M and C2M levels were assessed using biochemical assays.
• Radiographic progression was defined as an increase from baseline in the mSS score of at least 1 point at 1 year and of at least 5 points at 5 years.

TAKEAWAY:

• Baseline serum levels of C1M were 42% higher in patients who had progression of total joint damage at 1 year than in those without progression (median, 68 ng/mL vs 48 ng/mL; P < .0001).
• Patients with baseline serum levels of C1M in the highest quartile had increased odds of progression of total joint damage (adjusted odds ratio [aOR], 2.12; P = .03) and bone erosion (aOR, 3.80; P = .005) after adjusting for the Disease Activity Score-28, C-reactive protein levels, and anti-citrullinated protein antibody positivity.
• Median baseline serum levels of C1M were 33% higher in patients with progression of total joint damage at 5 years than in those without progression (P = .0037); each ng/mL increase in baseline serum levels of C1M was associated with an increased risk for progression after adjusting for age, sex, and BMI (P = .016).
• No significant associations were found between baseline serum levels of C2M and radiologic progression at either 1 or 5 years.

IN PRACTICE:

“[The] biological marker [C1M] may be combined with other biomarkers of disease activity to improve the identification of patients with early arthritis at high risk for progression,” the authors wrote.

SOURCE:

This study was led by Patrick Garnero of Inserm, Lyon, France. It was published online on July 10, 2025, in RMD Open.

LIMITATIONS:

At 5 years, radiologic data were available for only 60% of patients, limiting the robustness of the findings. Relationships of C1M and C2M levels with clinical progression were not analysed using the Disease Activity Score-28. Additionally, the effect of treatment groups during follow-up was not considered.

DISCLOSURES:

This study received an unrestricted grant from Merck Sharp and Dohme, with additional support from Inserm to support part of the biological database. The ESPOIR cohort study was supported by the French Society of Rheumatology, Pfizer, Abbvie, Lilly, Fresenius, and Biogen. One author disclosed being an employee of and owning stocks in Nordic Biosciences.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.