Pharmacodynamic Monitoring of Biological Therapies in Chronic Inflammatory Diseases

Background: Psoriasis, psoriatic arthritis, spondyloarthritis, rheumatoid arthritis, ulcerative colitis, and Crohn disease share similar underlying pathophysiological processes, providing the opportunity to treat the patients using similar biological therapies. Failure of biological treatments due to underexposure can be managed by therapeutic drug monitoring. Adjusting the treatment based on pharmacokinetic monitoring can be further improved by taking pharmacodynamic parameters such as clinical and molecular markers into account. Methods: Here, we critically evaluate the existing evidence, the hurdles to be taken, and the opportunities for a widespread implementation of pharmacodynamic monitoring. Results: Pharmacodynamic monitoring typically is the monitoring of biochemical markers. A pharmacodynamic marker preferably is specific for the pharmacological action of a drug, but most of the time nonspecific pharmacodynamic markers are used, such as C-reactive protein and the erythrocyte sedimentation rate. Clinical pharmacodynamic markers typically evaluate physical variables or symptoms. Although physician-reported outcomes have been studied for a longer time and often have been shown to correlate well with molecular pharmacodynamic markers and treatment outcomes, the introduction of mobile health or mHealth technologies caused a shift toward patient-reported outcomes, with the associated challenge to consistently reflect the inflammatory state, thereby preventing undertreatment or unnecessary overdosing of patients. Conclusions: The primary goal of pharmacodynamic monitoring is to optimize the response, but it can also have an impact on safety, costs, patient adherence, etc. Ideally, the constant remote monitoring of patient-reported disease activity is expected to become the standard, facilitated by mHealth technologies.