Optimalization of the clinical pharmacogenetic model to predict methotrexate treatment response: the influence of the number of haplotypes of MTHFR 1298A-677C alleles on probability to respond

The Potential Role of Genomic Medicine in the Therapeutic Management of Rheumatoid Arthritis

During the last decade, important advances have occurred regarding understanding of the pathogenesis and treatment of rheumatoid arthritis (RA). Nevertheless, response to treatment is not universal, and choosing among different therapies is currently based on a trial and error approach. The specific patient’s genetic background influences the response to therapy for many drugs: In this sense, genomic studies on RA have produced promising insights that could help us find an effective therapy for each patient. On the other hand, despite the great knowledge generated regarding the genetics of RA, most of the investigations performed to date have focused on identifying common variants associated with RA, which cannot explain the complete heritability of the disease. In this regard, rare variants could also contribute to this missing heritability as well as act as biomarkers that help in choosing the right therapy. In the present article, different aspects of genetics in the pathogenesis and treatment of RA are reviewed, from large-scale genomic studies to specific rare variant analyses. We also discuss the shared genetic architecture existing among autoimmune diseases and its implications for RA therapy, such as drug repositioning.

Genetic and epigenetic predictors of responsiveness to treatment in RA

Methotrexate and TNF-blocking agents are the DMARDs most commonly prescribed for the treatment of rheumatoid arthritis (RA). However, not all patients treated with these nonbiologic and biologic DMARDs respond satisfactorily and few predictors of treatment efficacy have been identified, despite the fact that these therapies have now been available for many years. Many studies have investigated genetic factors that might predict patient responsiveness to therapies used to treat RA, and epigenetic studies regarding response to treatment are expected to accumulate in the literature in the near future. Herein, we review the advances in identifying genetic and epigenetic predictors of therapeutic responses to methotrexate and/or TNF inhibitors in RA that have been made to date, and highlight important considerations for future studies, such as the need for an improved, preferably biological, outcome measure reflecting response to treatment.

TNF-α Polymorphisms in Juvenile Idiopathic Arthritis: Which Potential Clinical Implications?

Whether tumor necrosis factor alpha (TNF-α) gene polymorphisms (SNPs) influence disease susceptibility and treatment of patients with juvenile idiopathic arthritis (JIA) is presently uncertain. TNF-α is one of the most important cytokine involved in JIA pathogenesis. Several single nucleotide polymorphisms (SNPs) have been identified within the region of the TNF-α gene but only a very small minority have proven functional consequences and have been associated with susceptibility to JIA. An association between some TNF-α SNPs and adult rheumatoid arthritis (RA) susceptibility, severity and clinical response to anti-TNF-α treatment has been reported. The most frenquetly studied TNF-α SNP is located at -308 position, where a substitution of the G allele with the rare A allele has been found. The presence of the allele -308A is associated to JIA and to a poor prognosis. Besides, the -308G genotype has been associated with a better response to anti-TNF-α therapy in JIA patients, confirming adult data. Psoriatic and oligoarticular arthritis are significantly associated to the -238 SNP only in some works. Studies considering other SNPs are conflicting and inconclusive. Large scale studies are required to define the contribution of TNF-α gene products to disease pathogenesis and anti-TNF-α therapeutic efficacy in JIA.

Leveraging human genetics to develop future therapeutic strategies in rheumatoid arthritis

The purpose of this article is to place these genetic discoveries in the context of current and future therapeutic strategies for patients with RA. More specifically, this article focuses on (1) a brief overview of genetic studies, (2) human genetics as an approach to identify the Achilles heel of disease pathways, (3) humans as the model organism for functional studies of human mutations, (4) pharmacogenetic studies to gain insight into the mechanism of action of drugs, and (5) next-generation patient registries to enable large-scale genotype-phenotype studies.

Patient-tailored therapy in rheumatoid arthritis: an editorial review

PURPOSE OF REVIEW

The list of therapeutic targets for the treatment of rheumatic diseases constantly grows. As a consequence, a growing number of agents that are specifically directed against these targets become clinically available. However, the more diverse (and expensive) the armamentarium, the more its use should be guided by informed decisions for an optimal treatment. Such personalized, patient-tailored therapy is still not a reality in rheumatology practice. However, several important steps have recently been made towards achievement of this important goal.

RECENT FINDINGS

On the basis of the multifactorial nature of the pathogenesis of rheumatic diseases, the quest for single biomarkers that predict treatment response has proven difficult. Instead, biomarker signatures derived from genetic and proteomic expression studies using various biomaterials are being identified and demonstrate predictive value. Research focus has so far been placed on treatment responses to methotrexate and tumor necrosis factor antagonists, but interesting findings are already available for other agents as well.

SUMMARY

Although still in their infancy in rheumatology, personalized treatment approaches offer the potential for improved safety and efficacy for the patient and ultimately have promises to reduce societal costs.