Pharmacotherapy: concepts of pathogenesis and emerging treatments. Optimising the strategy of care in early rheumatoid arthritis

Biologic and oral disease-modifying antirheumatic drug monotherapy in rheumatoid arthritis

Clinical evidence demonstrates coadministration of tumour necrosis factor inhibitor (TNFi) agents and methotrexate (MTX) is more efficacious than administration of TNFi agents alone in patients with rheumatoid arthritis, leading to the perception that coadministration of MTX with all biologic agents or oral disease-modifying antirheumatic drugs is necessary for maximum efficacy. Real-life registry data reveal approximately one-third of patients taking biologic agents use them as monotherapy. Additionally, an analysis of healthcare claims data showed that when MTX was prescribed in conjunction with a biologic agent, as many as 58% of patients did not collect the MTX prescription. Given this discrepancy between perception and real life, we conducted a review of the peer-reviewed literature and rheumatology medical congress abstracts to determine whether data support biologic monotherapy as a treatment option for patients with rheumatoid arthritis. Our analysis suggests only for tocilizumab is there evidence that the efficacy of biologic monotherapy is comparable with combination therapy with MTX.

When and where does rheumatoid arthritis begin?

The major strides accomplished in elucidating the pathophysiology of rheumatoid arthritis (RA) have translated into therapeutic breakthroughs in clinical practice. However, currently available treatments work only for as long as they are taken. The development of curative treatments will probably require a better understanding of the earliest phases of RA and perhaps the identification of the etiological factors, which are probably numerous. These objectives are being pursued in studies of preclinical RA. The literature review presented herein indicates that the immunological conflict probably originates outside the joints, at mucous membrane sites and, more specifically, in the upper aerodigestive tract. The preclinical phase of RA can last for many years, and some patients probably never progress to arthritis. An immunological conflict develops then spins out of control, causing increases in autoantibody titers and subsequently in levels of serum markers for inflammation, before the development of the first joint symptoms. Improved knowledge of the preclinical phase, together with information from genetic markers, will allow the identification of profiles associated with susceptibility to RA and perhaps, in the future, the development of preventive strategies.

Clinical pharmacology of tocilizumab for the treatment of patients with rheumatoid arthritis

Tocilizumab is a humanized anti-IL-6 receptor (IL-6R) monoclonal antibody for the treatment of rheumatoid arthritis (RA). A dose of 8 mg/kg produces adequate blockade of IL-6 receptors throughout a dosing interval, as confirmed by sustained high levels of tocilizumab-bound soluble IL6-R complex and normalization of C-reactive protein levels. Studies have confirmed 8 mg/kg every 4 weeks as the optimal dose and 4 mg/kg as the starting dose for the treatment of RA, with favorable efficacy and acceptable safety profiles. After 8 mg/kg, steady-state peak and trough concentrations were 183 ± 86 and 9.7 ± 11 µg/ml, respectively. Tocilizumab serum exposures increased more than proportionally to the dose increase from 2-10 mg/kg. Total clearance is concentration dependent, with non-linear receptor-mediated clearance dominant at low concentrations (<25 µg/ml). Tocilizumab exposures are not affected by common concomitant medications in RA patients, but decreased IL-6 activity resulted in increased CYP3A4 activity and hence decreased exposures of CYP3A4 substrates.

Rheumatoid arthritis: treating to target with disease-modifying drugs

Treating to target is an established concept in a number of long-term conditions, which aims to improve outcomes and prevent disease progression. Treatment targets in rheumatoid arthritis (RA) are to control the signs and symptoms of significant inflammatory disease activity, with the ultimate goal of remission from disease. Assessment of patients' disease activity includes clinical examination of the number of swollen and tender joints, combined with measurement of inflammatory markers and visual analogue scales of patients' overall wellbeing and symptoms. Early initiation and rapid dose escalation of disease-modifying anti-rheumatic drugs (DMARDs) has been shown to be crucial to optimizing disease control, protecting joints from destruction and preserving health-related quality of life. Corticosteroids can be prescribed for oral use but are often given by intra-muscular or joint injection in times of flare to minimize the risks of side effects. The rational use of non-steroidal anti-inflammatory drugs and analgesia remains important to symptom management throughout the patient journey. In part two of this three-part series, the concept of treating to target in rheumatoid arthritis is outlined, including the role of the nurse in optimizing outcomes and an overview of treatment options using conventional DMARDs. Part three will cover the use of biologic agents, which have increased treatment options for RA, but their use is reserved for patients with severe disease activity who have failed to respond to adequate trials of DMARDs.

MMP-Activated Fluorescence Imaging Detects Early Joint Inflammation in Collagen-Antibody-Induced Arthritis in CC-Chemokine Receptor-2-Null Mice, In-Vivo

The Standard measures of experimental arthritis fail to detect, visualize, and quantify early inflammation and disease activity. Here, we describe the use of an injectable MMP-activated fluorescence agent for in vivo quantification of acute inflammation produced by collagen-antibody-induced arthritis (CAIA) in CC chemokine receptor-2 (Ccr2^−/−) null mice. Although Ccr2^−/− DBA1/J mice were highly susceptible to and rapidly developed CAIA, the standard clinical assessment of fore or hind paw thicknesses was unable to detect significant acute inflammatory changes (days 3–10). Remarkably, noninvasive, in situ, MMP-activatable fluorescent imaging of Ccr2^−/− DBA1/J mice with CAIA displayed acute joint pathology in advance of clinically measurable acute inflammation (days 5, 7, and 10). These results were confirmed by the histology of ankle joints, which showed significant inflammation, bone loss, and synovial hyperplasia, compared to control mice at postimmunization day 5. The MMP-mediated fluorescence technique holds tremendous implications for quantifiable examination of arthritis disease activity of acute joint inflammation.