Malignancy outcomes in patients with rheumatoid arthritis treated with abatacept and other disease-modifying antirheumatic drugs: Results from a 10-year international post-marketing study

•International, up to 10-year observational safety study in patients with RA.•No significant increased risk of overall malignancy with abatacept vs cs/b/tsDMARDs.•No increased risk of breast cancer with abatacept compared with cs/b/tsDMARDs.•No increased risk of lung cancer with abatacept compared with cs/b/tsDMARDs.•ARTIS showed significantly increased risk of lymphoma with abatacept vs b/tsDMARDs. To evaluate the risk of malignancy (overall, breast, lung, and lymphoma) in patients with rheumatoid arthritis treated with abatacept, conventional synthetic (cs) disease-modifying antirheumatic drugs (DMARDs), and other biologic/targeted synthetic (b/ts)DMARDs in clinical practice. Four international observational data sources were included: ARTIS (Sweden), RABBIT (Germany), FORWARD (USA), and BC (Canada). Crude incidence rates (IRs) per 1000 patient-years of exposure with 95% confidence intervals (CIs) for a malignancy event were calculated; rate ratios (RRs) were estimated and adjusted for demographics, comorbidities, and other potential confounders. RRs were then pooled in a random-effects model. Across data sources, mean follow-up for patients treated with abatacept (n = 5182), csDMARDs (n = 73,755), and other b/tsDMARDs (n = 37,195) was 3.0–3.7, 2.9–6.2, and 3.1–4.7 years, respectively. IRs per 1000 patient-years for overall malignancy ranged from 7.6–11.4 (abatacept), 8.6–13.2 (csDMARDs), and 5.0–11.8 (other b/tsDMARDs). IRs ranged from: 0–4.4, 0–3.3, and 0–2.5 (breast cancer); 0.1–2.8, 0–3.7, and 0.2–2.9 (lung cancer); and 0–1.1, 0–0.9, and 0–0.6 (lymphoma), respectively, for the three treatment groups. The numbers of individual cancers (breast, lung, and lymphoma) in some registries were low; RRs were not available. There were a few cases of lymphoma in some of the registries; ARTIS observed an RR of 2.8 (95% CI 1.1–6.8) with abatacept versus csDMARDs. The pooled RRs (95% CIs) for overall malignancy with abatacept were 1.1 (0.8–1.5) versus csDMARDs and 1.0 (0.8–1.3) versus b/tsDMARDs. This international, post-marketing observational safety study did not find any statistically significant increase in the risk of overall malignancies in pooled data in patients treated with abatacept compared with csDMARDs or with other b/tsDMARDs. Assessment of larger populations is needed to further evaluate the risks for individual cancers, especially lymphoma.