Despite multiple existing conventional synthetic disease-modifying antirheumatic drug (csDMARD) and biologic DMARD (bDMARD) options, many patients with rheumatoid arthritis (RA) do not respond adequately to treatment. In an exciting development, a recent phase 2 study by Tuttle and colleagues examined a novel treatment approach in RA: stimulation of the programmed cell death protein 1 (PD-1) inhibitor pathway. PD-1 is a checkpoint inhibitor receptor whose activation reflects T-cell activation and may play a role in synovitis and extra-articular inflammation. Blocking PD-1 in cancer therapy has been associated with an increase in inflammatory arthritis. In this 12-week study, RA disease activity was analyzed in patients randomly assigned to two different monthly intravenous doses of peresolimab or placebo. Of note, a large majority of participants were seropositive for rheumatoid factor (RF) or cyclic citrullinated peptide (CCP). Patients receiving the 700-mg dose of peresolimab had a better American College of Rheumatology (ACR) 20 response than did those receiving placebo (71% vs 42%), but not a better ACR50 or ACR70 response; the 300-mg dose was not better than placebo. Although reported adverse events were similar in all three groups, with a short timeframe it would be difficult to address concerns about cancer risk. Though this novel treatment is exciting, a larger and longer-term trial is necessary to address this concern as well as potentially tease out risk factors (including age or other immunosuppression) in this susceptible group.
Two other studies examined use of a much older csDMARD therapy, hydroxychloroquine (HCQ), in Brazilian patients with RA. Bredemeier and colleagues looked at the effects of HCQ on adverse events as well as the persistence of bDMARD/targeted synthetic DMARD (tsDMARD) therapy in over 1300 patients with RA. Using the BiobadaBrasil registry of patients starting their first bDMARD or Janus kinase (JAK) inhibitor, they looked at effects of combination therapy with HCQ during the treatment course of up to six bDMARD or JAK inhibitors. At baseline, patients prescribed antimalarial therapy had shorter RA duration and began treatment earlier, perhaps due to patient or physician preferences regarding starting "milder" antimalarial medication earlier or due to use of "triple therapy" with methotrexate and sulfasalazine. Of interest, patients receiving antimalarial therapy had a lower incidence of adverse events, especially serious infections, but no effect on cardiovascular events was seen despite HCQ's perceived beneficial effects on thrombotic risk and cholesterol profile. Patients receiving HCQ were also more likely to persist in their course of bDMARD or JAK inhibitor therapy, though the effect size seems relatively small. As the focus in this study was on adverse effects, the authors' analysis of the effects on antimalarials on the persistence of therapy was not detailed.
Lin and colleagues also looked at the effects of HCQ in patients with older-onset RA with respect to mortality risk. Using data from the electronic health records of a hospital in Taiwan, mortality-associated risk factors were evaluated in 980 patients with RA diagnosed at >60 years. Male sex, current smoking status, and cancer status were all associated with mortality, whereas HCQ use was associated with reduced mortality (hazard ratio 0.30). In contrast to the registry study mentioned above, patients receiving HCQ had a lower risk for cardiovascular events, hyperlipidemia, diabetes, and chronic kidney disease. Interaction with cancer was less clear due to lower number of patients. Of interest, use of cyclosporine, leflunomide, and a bDMARD was associated with higher mortality risk. The source and true relevance of the potential risk reduction in this study is not clear because of the lack of prospective data, but combined with the information above, this study suggests that the benefits of HCQ use should not be discounted in patients with RA.