Tocilizumab and missed personalized medicine opportunities for patients with rheumatoid arthritis?

IL-6 pathway-driven investigation of response to IL-6 receptor inhibition in rheumatoid arthritis

OBJECTIVES

To determine whether heterogeneity in interleukin-6 (IL-6), IL-6 receptor and other components of the IL-6 signalling pathway/network, at the gene, transcript and protein levels, correlate with disease activity in patients with rheumatoid arthritis (RA) and with clinical response to tocilizumab.

DESIGN

Biomarker samples and clinical data for five phase 3 trials of tocilizumab were analysed using serum (3751 samples), genotype (927 samples) and transcript (217 samples) analyses. Linear regression was then used to assess the association between these markers and either baseline disease activity or treatment response.

RESULTS

Higher baseline serum IL-6 levels were significantly associated (p<0.0001) with higher baseline DAS28, erythrocyte sedimentation rate, C reactive protein and Health Assessment Questionnaire in patients whose responses to disease-modifying antirheumatic drugs (DMARD-IR) and to antitumour necrosis factor (aTNF-IR) were inadequate and patients who were naive/responders to methotrexate (MTX). Higher baseline serum IL-6 levels were also significantly associated with better clinical response to tocilizumab (versus placebo) measured by cDAS28 in the pooled DMARD-IR (p<0.0001) and MTX-naive populations (p=0.04). However, the association with treatment response was weak. A threefold difference in baseline IL-6 level corresponded to only a 0.17-unit difference in DAS28 at week 16. IL-6 pathway single nucleotide polymorphisms and RNA levels also were not strongly associated with treatment response.

CONCLUSIONS

Our analyses illustrate that the biological activity of a disease-associated molecular pathway may impact the benefit of a therapy targeting that pathway. However, the variation in pathway activity, as measured in blood, may not be a strong predictor. These data suggest that the major contribution to variability in clinical responsiveness to therapeutics in RA remains unknown.

[Personalized medicine in cytokine-targeted therapy]

Personalized healthcare tries to predict the effectiveness and safety in individual therapeutic approaches by defining individual patient characteristics (biomarkers), while stratification uses diagnostic patterns for groups of patients for prediction of therapeutic response with less adverse reactions caused by the drugs applied. Both methods are implemented in oncology and infectiology and in the therapy of rheumatological diseases there is a need for both. Cytokine-directed therapies are important for the treatment of rheumatological diseases, especially when therapy with conventional disease-modifying antirheumatic drugs (DMARD) has failed. Despite the high potency of these drugs for inhibiting pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α), interleukin 1 (IL-1) and IL-6, sufficient responses are only seen in some of the patients. Therefore, stratification and personalized medicine are ways to optimize efficacy and tolerability of biologic therapies. Some initial evidence is available for potential future strategies using molecular and genetic markers for stratified cytokine inhibition.

Systems diagnostics: anticipating the next generation of diagnostic tests based on mechanistic insight into disease

Societal demand for faster and more accurate assignment of treatments is based in both patient care needs and in health economics. From a patient care standpoint, there needs to be a transformation from the empiric method of therapeutic decision making to avoid unwanted side effects from inefficacious treatments. For health economics, the delay in effective therapy and expenditures for ineffective therapies add to the burden of care. To accomplish this transformation, we need to modify our current method of classifying disease from a phenotypic description to one that incorporates the different molecular drivers that created the observed phenotype. To do so, a deeper, systems-based understanding of these disease drivers is required, which will yield a new generation of diagnostic tests, or systems diagnostics.

Clinical safety of tocilizumab in rheumatoid arthritis

IMPORTANCE OF THE FIELD

Tocilizumab is a new biologic disease-modifying antirheumatic drug directed against the activity of IL-6, a key pro-inflammatory cytokine in the pathogenesis of rheumatoid arthritis (RA). This drug has proved highly effective in RA patients, including those who had previously not responded to anti-TNFs. As side effects are a major cause for discontinuing biologic therapy, the present article focuses on the tolerability profile of tocilizumab.

AREAS COVERED IN THIS REVIEW

This review describes the adverse events (AEs) reported in RA patients treated with tocilizumab. Most data are derived from controlled clinical trials and their open-label extensions.

WHAT THE READER WILL GAIN

The reader will gain a comprehensive review of treatment-emergent AEs associated with tocilizumab therapy. These AEs include infections, including opportunistic infections, infusion and hyper-sensitivity reactions, gastrointestinal perforation, and laboratory test abnormalities, especially hepatic transaminase elevations, altered lipid profile and neutropenia.

TAKE HOME MESSAGE

Based on current data, tocilizumab appears to have an acceptable safety profile inasmuch as most AEs were manageable or controllable. However, results from large scale pharmacoepidemiological investigations and appropriate post-marketing surveillance are awaited to identify the full spectrum of AEs and define the true benefit:risk ratio of tocilizumab.

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.