Rheumatoid arthritis (RA) is a chronic, symmetrical, autoimmune disease characterized by inflammation of the joints, as well as damage to a variety of body systems, including the skin, eyes, lungs,... Show moreRheumatoid arthritis (RA) is a chronic, symmetrical, autoimmune disease characterized by inflammation of the joints, as well as damage to a variety of body systems, including the skin, eyes, lungs, heart and blood vessels. Therefore, to prevent (potential) damage with a more favorable course of the disease, it is important to intervene both early and agressively with medication in the treatment of RA. Typically, methotrexate is used as the first treatment, possibly in conjuction with other disease-modifying antirheumatic drugs, or with prednisolone to reduce inflammation rapidly. While the treatment of RA has improved considerably in recent decades, drug treatment does not work for everyone due to toxicity or lack of responsiveness. Therefore, it is suspected that genetics plays a major role in the both efficacy and toxicity of current RA medication. The goal of this thesis is to identify the genetic factors that influence the effectiveness or toxicity of the drugs used in RA. Show less
The primary objective of this thesis is to investigate the role of pharmacogenetics in predicting drug response in treatments for the autoimmune diseases: RA and SLE. For this reason, this thesis... Show moreThe primary objective of this thesis is to investigate the role of pharmacogenetics in predicting drug response in treatments for the autoimmune diseases: RA and SLE. For this reason, this thesis is divided in two parts: pharmacogenetics related with drugs used in RA and pharmacogenetics of rituximab used in SLE and other autoimmune diseases. Part 1: Pharmacogenetics of drugs used in RA MTX is the most common DMARD used in RA. However, its use is hampered by frequent adverse drug events among which gastrointestinal toxicity is most frequent. Hepatotoxicity is a relatively rare but serious adverse event related to the use of MTX and is largely unpredictable. In chapter 2 an overview is presented of the previously performed studies concerning pharmacogenetic predictive biomarkers for MTX-induced hepatotoxicity. Treatment with anti-TNF agents results in a reduction of disease activity in most RA patients. However, a substantial part of patients does not respond to this therapy for unknown reasons. It would be highly beneficial to be able to predict whether or not an individual patient responds to treatment. Chapters 4 and 5 describe the investigations on the role of different candidate SNPs related to the efficacy of the treatment with different anti-TNFs in RA. In addition, in chapter 3 a replication study is presented based on 4 polymorphisms that were found associated with anti-TNF response in RA in a previously published genomewide association study. Part 2: Pharmacogenetics of rituximab used in SLE and other autoimmune diseases In chapters 6–8 the role of different genetic variants related to the pharmacodynamics of the drug or of the diseases are evaluated to study the contribution to differences in the response to rituximab in patients with SLE and other systemic autoimmune diseases. In chapter 6, the possible involvement of the -174 IL-6 polymorphism in the clinical response to rituximab in different systemic autoimmune diseases is assessed. In chapter 7, the aim is to investigate the possible involvement of the FCGR3A-158F/V polymorphism in the clinical response to rituximab in Spanish patients with different systemic autoimmune diseases. In chapter 8, the role of G/T polymorphism at the IL2–IL21 region in the rituximab response in a cohort of SLE patient and different autoimmune disorders is analyzed. Chapter 9 provides a summary of this thesis, chapter 10 the Dutch summary (Nederlandse samenvatting), and chapter 11 the general discussion and future perspective of this thesis. Show less
Results from this thesis have elucidated potential genetic markers, which were associated with treatment outcome to MTX and adalimumab. Furthermore, a model for predicting the efficacy of MTX in... Show moreResults from this thesis have elucidated potential genetic markers, which were associated with treatment outcome to MTX and adalimumab. Furthermore, a model for predicting the efficacy of MTX in patients with RA was validated in two cohorts indicating that predicting efficacy by a pharmacogenetic model is feasible in RA patients treated with MTX. Importantly, definitive conclusions about the role of genetic predictive factors in treatment outcome to DMARDS could not be drawn, since these results have to be further validated and replicated in future pharmacogenetic studies. Large randomized prospective studies should be planned to demonstrate its legitimate predictive and cost-effective value before a genetically individualized approach is applicable in daily clinical practice. The potential role of pharmacogenetics in the prediction of efficacy and adverse events in RA patients treated with DMARDs is presented in this thesis. Hereby, new knowledge is added to the relatively young research field of pharmacogenetics, which may hopefully lead to a better treatment strategy for RA patients Show less
