Vinod Chandran, MBBS, MD, DM, PhD
Two new papers published recently provide evidence of the efficacy and safety of bimekizumab in psoriatic arthritis (PsA). Bimekizumab is a novel bispecific monoclonal antibody targeting interleukin (IL)-17A and IL-17F and is already approved for the treatment of chronic plaque psoriasis. McInnes and colleagues reported the results of the phase 3 BE OPTIMAL study, which included 852 patients with active PsA who were naive to biologic disease-modifying antirheumatic drugs (bDMARD) and were randomly assigned to receive bimekizumab, placebo, or adalimumab. At week 16, a significantly higher proportion of patients receiving bimekizumab vs placebo achieved ≥ 50% improvement in American College of Rheumatology response (ACR50; 44% vs 10%; odds ratio [OR] 7.1; P < .0001). Compared with placebo, significant improvements were also noted in psoriasis, enthesitis, and dactylitis in the bimekizumab group and there was less progression of radiographic damage.
Bimekizumab was also demonstrated to be beneficial in PsA patients with inadequate response or intolerance to tumor necrosis factor inhibitors (TNFi). In the phase 3 BE COMPLETE study, which included 400 patients with active PsA and previous inadequate response or intolerance to TNFi, patients were randomly assigned to receive 160 mg subcutaneous bimekizumab every 4 weeks or placebo. Merola and colleagues reported that at week 16, a significantly higher proportion of patients receiving bimekizumab vs placebo achieved ACR50 response (43% vs 7%; OR 11.1; P < .0001). Thus, bimekizumab is a welcome addition to the treatment portfolio we have for PsA. In regard to side effects of special concern when inhibiting IL-17, bimekizumab was associated with higher risk for oral and genital candidiasis, occurring in 4% of the treated patients within 16 weeks in the two studies; however, no cases of systemic fungal infections occurred. The incidence of inflammatory bowel disease was also very low, but head-to-head studies against other available agents would be required to help rheumatologists decide the place of bimekizumab in PsA management.
A common clinical question is whether axial PsA is similar to ankylosing spondylitis (AS) with psoriasis. Assuming that it is, clinicians have used treatments approved for AS for managing axial PsA. Recent studies have questioned this assumption, however. Michelena and colleagues conducted a cross-sectional study that included 109 patients with axial PsA and 127 patients with AS and psoriasis from the REGISPONSER registry. Compared with patients with AS and psoriasis, patients with human leukocyte antigen (HLA)-B27–negative axial PsA had less inflammatory pain (P = .002), anterior uveitis (P = .014), and structural damage (P < .001), along with a higher prevalence of nail disease (P = .009). Patients with HLA-B27–positive axial PsA vs AS and psoriasis were similar but had less structural damage to the spine (P < .001). Thus, there seem to be significant clinical and genetic differences between these two diseases that require further investigation. Lack of an accepted definition of axial PsA, however, is a hindrance to multiple high-quality genetic, clinical, and interventional studies comparing axial PsA and AS with psoriasis.
Observational studies have recognized the clinical and familial association between psoriatic disease and Crohn's disease (CD), but such cross-sectional or retrospective studies cannot identify causal relationships. Mendelian randomization is a method used to identify causal relationships. Using this method, Sun and colleagues demonstrated that PsA was associated with a 31.9% increased risk for CD (P < .001) and genetically predicted CD was linked to a 44.8% higher risk for PsA (P = .001). No such association was found with ulcerative colitis. Thus, there is a bidirectional causal relationship between the two diseases. Patients with PsA should be evaluated for symptoms of CD, and those with CD for psoriatic disease, to facilitate early diagnosis and better long-term outcomes.