Tocilizumab Associated With Higher Risk of Neutropenia Among Biologic DMARDs

History of neutropenia with methotrexate, concurrent treatment with synthetic disease-modifying antirheumatic drugs (sDMARDs), and tocilizumab were risk factors for developing neutropenia while on biologic DMARDs (bDMARDs), according to a study published in The Journal of Rheumatology.

While bDMARDs have redefined the treatment of rheumatic diseases, certain abnormalities, such as neutropenia, have been reported. However, few studies have so far investigated bDMARD-induced neutropenia in the real world.

“Because the major serious event of biologics is infection, a serious concern is whether bDMARD-induced neutropenia could eventually increase this risk,” the authors wrote.

They examined neutropenia in a cohort of patients treated with 3 classes of intravenous bDMARD: the CTLA-4 antagonist abatacept; the TNF-α inhibitor infliximab; and the interleukin-6 inhibitor tocolizumab. They analyzed incidence, risk factors, and effect of neutropenia on the risk of infection and drug survival, which is the length of time a patient continues to take a particular drug and includes factors such as drug effectiveness and side effects.

Overall, the study included 499 patients with data collected from medical records. The mean age of the participants was 57 years, women accounted for 83% of the population, rheumatoid arthritis was the most common diagnosis (72.3%). Approximately 10% of patients had at least 1 episode of neutropenia and 96% of them had more than 5 episodes.

The authors found that neutropenia was most common with tocilizumab with 18.6% of the group having neutropenia compared with 2.8% of those on infliximab and 3.8% on abatacept. Most of the patients receiving infliximab and abatacept had a history of neutropenia, while 93% of the patients treated with tocilizumab were experiencing their first event.

Neutropenia with tocilizumab “seemed to be dose-dependent,” the authors wrote. In patients starting at 6 mg/kg of tocilizumab, there was just a 7.2% incidence of neutropenia compared with 25.8% of patients who started tocilizumab at 8 mg/kg. Ultimately, the authors found no differences in the rate of infection between patients taking tocilizumab who had and didn’t have neutropenia.

“We believe that the data presented here permit a better perspective on the problem regarding frequency, severity, associated risk factors, and consequences,” the authors concluded.