Risk of Malignancies in Patients with Rheumatoid Arthritis Treated with Rituximab: Analyses of Global Postmarketing Safety Data and Long-Term Clinical Trial Data

Introduction: Patients with rheumatoid arthritis (RA) are at an increased risk of developing malignancies, but it is unclear whether this increased risk is the result of disease pathobiology or immunosuppressant treatments for RA. This analysis evaluated the potential risk of malignancy in patients with RA treated with rituximab (MabThera®/Rituxan®) a CD20+ B-cell depleting agent manufactured by F. Hoffmann-La Roche Ltd.

Methods: Malignancy rates were obtained from the rituximab global company safety database for adverse event reporting and from the rituximab global clinical trial program for RA consisting of eight randomized clinical trials, two long-term open-label extensions, and one open-label prospective study. Global company safety database searches were performed using the standard Medical Dictionary for Regulatory Activities (MedDRA) queries “Malignant tumors wide” and “Skin malignant tumors wide” up to April 30, 2017. Age- and sex-specific comparator values from the general population were obtained from the US National Cancer Institute Surveillance, Epidemiology, and End Results (SEER) database.

Results: For the 409,706 patients with RA in the rituximab global company safety database since first market approval in 2006, 1739 cumulative malignant events were reported, with an overall malignancy reporting rate of approximately 4.2 events per 1000 patients. No evidence of increased risk of malignancy, of any organ-specific type, was found following rituximab treatment. The rate of malignancies from rituximab-treated patients in RA clinical trials was 7.4 per 1000 patient-years. This is within the expected range, with no evidence for increased risk over time or with additional rituximab courses.

Conclusions: Analyses of the global postmarketing safety database and long-term clinical trial data showed no evidence of an increased risk of malignancy of any type following rituximab treatment in patients with RA.

Funding: F. Hoffmann-La Roche Ltd.