Because this study involves retrospective data from real-world practices, determining an association depends on propensity score matching, an analytic approach that allows comparison of similar patient populations in terms of demographic and clinical features. Using this approach, the investigative team studied 8,931 patients in two groups differing in the use of anti-IL-17 agents.
The data indicated that those patients treated with an anti-IL-17 agent had a slightly lower risk of developing Crohn’s disease than the comparator population, but the risk for developing ulcerative colitis was significantly lower.
These findings are notable and provide valuable information to consider when prescribing biological therapies for PsA. Further, they may involve rethinking the role of certain cytokines in the pathogenesis of different inflammatory diseases and the idea that an anti-cytokine can improve one condition at the same time it provokes or worsens another.
3. Obesity & PsA Treatment Response
Mehta et al. Abstract 26913
Classically, immune-mediated diseases, such as inflammatory arthritis, have been associated with weight loss, likely reflecting the metabolic effects of cytokines. TNF is the prime example of such a cytokine because it was originally described on the basis of its effects on weight loss (cachexia) and called cachectin. When the molecular structures of cytokines were determined, amino acid sequence analysis showed that cachectin was, in fact, the same cytokine as tumor necrosis factor, so named because of its ability to kill tumors in model systems. Despite the propensity of inflammation to cause weight loss, clinical studies have indicated that obesity and being overweight are common among patients with PsA. In this study, Mehta and colleagues characterized clinical features of 1,291 patients with PsA and determined the influence of weight on the response to therapy.
As the data showed, a higher body mass index (BMI) was significantly associated with a lower chance of achieving minimal disease activity (MDA), with BMI related to worse outcomes in multiple subcomponents of the MDA (e.g., enthesis, tender joint count, pain but not swollen joint count). Further, BMI at the time of drug initiation was associated with a reduced chance for MDA in patients treated with a TNF inhibitor (TNFi), and the TNFi group excluding infliximab; infliximab has weight-based dosing. BMI, however, did not influence the response to other agents.
Because weight may influence the response to cytokine inhibition due to effects on pharmacokinetics, these studies are important in formulating treatment plans for patients with PsA and, most pertinently, to encourage patients to embark upon a program of weight reduction by pharmacologic or non-pharmacologic means.
