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Previously, we showed that the combination of methotrexate and adalimumab treatment leads to less antidrug antibody development. In this study, we quantify the pharmacokinetics/pharmacodynamics (PK/PD) of adalimumab and evaluate the influence of methotrexate cotreatment. A population PK-PD model was developed using prospective data from 59 patients with psoriasis (baseline PASI = 12.6) receiving adalimumab over 49 weeks. Typical PK and PD parameters and their corresponding interpatient variability were estimated. We performed a covariate analysis to assess whether interpatient variability could be explained by addition of methotrexate and other covariates. In total, 330 PASIs, 252 adalimumab serum concentrations, and 247 antidrug antibody titers were available. Presence of antidrug antibodies (adalimumab group = 46.7%, adalimumab + methotrexate group = 38.7%; P = .031) was correlated with increased adalimumab apparent clearance (P < .001). In the PD model, the use of concomitant methotrexate was borderline to significantly correlated with a decreased half-maximal inhibitory concentration (adalimumab concentration for which clinical response score is reduced by half; P < .10). On the basis of our PK-PD model, concomitant use of methotrexate indirectly increases adalimumab concentration, partially through less antidrug antibodies formation, which may result in better efficacy., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Introduction: Adalimumab is normally prescribed with methotrexate (MTX) in rheumatoid arthritis given the enhanced treatment effect and reduced antidrug antibody formation compared with adalimumab monotherapy (ADL). In psoriasis, the long-term treatment effects and pharmacokinetic profile have not been investigated extensively., Methods: We conducted a randomized controlled trial to assess the efficacy, safety, pharmacokinetics, and immunogenicity of adalimumab combined with MTX 10 mg per week (ADL-MTX group) compared with that of ADL (ADL group) in chronic plaque psoriasis., Results: A total of 31 patients in the ADL-MTX group and 30 in the ADL group were analyzed. After 1 year, a (nonsignificant) better drug survival was found in the ADL-MTX group (74.2 vs. 58.6%, P = 0.15). The PASI 75 response in week 49 was 58.1 versus 36.7% (P = 0.13), and the median (interquartile range) serum-trough concentrations were 6.8 (5.5‒9.2) versus 5.9 (3.5‒8.8) mg/l (P = 0.26) in the ADL-MTX group and ADL group, respectively. Fewer patients showed antidrug antibodies in the ADL-MTX group (22.6 vs. 60.0%, P < 0.01). No serious adverse events occurred., Conclusion: Combination therapy of adalimumab and MTX results in fewer patients showing antidrug antibodies, with a trend toward a better PASI 75 response, drug survival, and higher serum-trough concentrations than ADL. Patient-reported outcomes and adverse events were comparable between the groups., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: In shared decision making (SDM), patients and physicians work together to choose the best treatment option for an individual patient. Atopic dermatitis (AD) and psoriasis are particularly suitable for SDM, considering that the best treatment option depends on a patient's preferences and values (preference-sensitive decisions). Currently, it is unknown to what extent SDM is applied in treatment decisions for these diseases in the Netherlands., Objectives: Primary, to assess the current extent of SDM in AD and psoriasis in the Netherlands amongst patients and dermatologists. Secondary, to assess the degree to which patients and physicians endorse SDM, to explore which characteristics are related to their preference to be involved in SDM and to identify which barriers and facilitators for SDM they perceive., Methods: Two similar online surveys, one for patients with AD or psoriasis and one for (resident) dermatologists, were carried out. The surveys comprised validated questionnaires (shared decision making questionnaire (SDM-Q; range 0-100), Control Preference Scale) and study-specific statements mainly regarding barriers and facilitators for SDM., Results: The responses of 219 patients and 147 physicians were analysed. Dermatologists experienced significantly more SDM than patients (SDM-Q 82 vs 55; P < 0.01). Most patients and dermatologists prefer to share treatment decisions. Mainly facilitators for SDM were perceived, including the positive perception of patients and dermatologists regarding SDM. The perceived barriers included lack of continuity of care by the same physician and lack of time., Conclusion: Despite the dermatologists' optimistic perspective, patients experience a limited extent of SDM and physicians should be aware of this gap. Improvement of SDM in AD and psoriasis is needed. The positive attitude of patients and dermatologists towards the process and outcome of SDM is important facilitators, while barriers were mainly perceived on an organizational level., (© 2020 AMC/University of Amsterdam. Journal of the European Academy of Dermatology and Venereology published by John Wiley & Sons Ltd on behalf of European Academy of Dermatology and Venereology.)