Rituximab and Abatacept May Contribute to Cancer Risk in RA

TOPLINE:

The initiation of biologic or targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARDs), particularly rituximab and abatacept, is associated with an increased risk for incident cancer in patients with rheumatoid arthritis (RA) within 2 years of starting treatment.

METHODOLOGY:

• The researchers conducted a retrospective cohort study to assess the safety of tumor necrosis factor (TNF) inhibitors, non-TNF inhibitors, and Janus kinase (JAK) inhibitors in patients with RA using US administrative claims data from the Merative Marketscan Research Databases from November 2012 to December 2021.
• A total of 25,305 patients with RA (median age, 50 years; 79% women; 49% from the South United States) were identified using diagnostic codes on or before treatment initiation.
• Treatment exposures, including the initiation of TNF inhibitors (adalimumab, etanercept, certolizumab pegol, golimumab, and infliximab), non-TNF inhibitors (abatacept, interleukin 6 [IL-6] inhibitors, and rituximab), and JAK inhibitors (tofacitinib, baricitinib, and upadacitinib), were compared.
• The primary outcome was any incident cancer (excluding nonmelanoma skin cancer) occurring after a minimum of 90 days and within 2 years of treatment initiation.
• Sensitivity analyses used 1:1 propensity matching to compare cancer rates between populations treated with rituximab, IL-6 inhibitors, abatacept, or JAK inhibitors and matched reference populations treated with TNF inhibitors.

TAKEAWAY:

• Rituximab (adjusted hazard ratio [aHR], 1.91; 95% CI, 1.17-3.14) and abatacept (aHR, 1.47; 95% CI, 1.03-2.11) were significantly associated with an increased risk for incident cancer, compared with TNF inhibitors.
• In the propensity-matched analysis, a statistically significant increase in risk was observed in patients treated with rituximab (aHR, 4.37; 95% CI, 1.48-12.93) and abatacept (aHR, 3.12; 95%CI, 1.52-6.44).
• IL-6 inhibitors showed no significant association with cancer in the primary analysis, but a significantly increased risk was observed in the propensity-matched analysis (HR, 5.65; 95% CI, 1.11-28.79).
• JAK inhibitors were not associated with a significant increase in the risk for cancer, compared with TNF inhibitors.

IN PRACTICE:

“Given the limitations of using private insurance claims data and confounding by indication, it is likely that these patients may have a higher disease burden, resulting in channeling bias,” the authors wrote. “To understand these associations, larger studies with longer follow-up and more granular collection of data, including medication indications and RA disease activity measures, would be needed for better comparison of incident cancer risk among these drugs,” they added.

SOURCE:

The study was led by Xavier Sendaydiego, MD, University of Washington, Seattle. It was published online on November 20, 2024, in JAMA Network Open.

LIMITATIONS:

A relatively small number of cancer outcomes may have affected the ability to adjust for confounders. The follow-up period was limited to 2 years, potentially missing long-term cancer risks. The use of US-specific administrative claims data, including only patients aged 18-64 years, may limit the generalizability of the findings. Additionally, the claims data lacked direct measures of disease activity or severity of RA, and information on treatment adherence was unavailable, leading to potential misclassification.

DISCLOSURES:

The study was supported by grants from the National Institute of Arthritis and Musculoskeletal and Skin Diseases and the National Institute on Aging. Some authors reported receiving personal fees, nonfinancial support, and grants from various pharmaceutical companies or government sources. One author reported having a pending patent and another author reported receiving a fellowship, travel reimbursement, and royalties outside the submitted work.

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