Tuberculosis associated with therapy against tumor necrosis factor α

Infectious complications associated with monoclonal antibodies and related small molecules

Biologics are increasingly becoming part of routine disease management. As more agents are developed, the challenge of keeping track of indications and side effects is growing. While biologics represent a milestone in targeted and specific therapy, they are not without drawbacks, and the judicious use of these "magic bullets" is essential if their full potential is to be realized. Infectious complications in particular are not an uncommon side effect of therapy, whether as a direct consequence of the agent or because of the underlying disease process. With this in mind, we have reviewed and summarized the risks of infection and the infectious disease-related complications for all FDA-approved monoclonal antibodies and some related small molecules, and we discuss the probable mechanisms involved in immunosuppression as well as recommendations for prophylaxis and treatment of specific disease entities.

Tumor necrosis factor inhibitors and infection complications

Rheumatoid arthritis patients are at heightened risk for infections because of intrinsic disease severity with associated inflammation, comorbid illnesses, and use of glucocorticoids and various immunosuppressives. Although several studies have reported up to a twofold increase in risk of serious infections in RA patients treated with anti-tumor necrosis factor-alpha agents, results from other studies have been conflicting. Comparing results from different studies is challenging because of differences in patient populations, heterogeneous prevalence of comorbidities, and differing patterns of concomitant medication use. Based on available evidence, an excess risk for infection occurs early after initiation of tumor necrosis factor-alpha inhibitor therapy. Additionally, special circumstances such as surgical procedures may increase infection risk. The appropriate use of biologics in the perioperative setting remains empiric at best.

Tumor necrosis factor (TNF) inhibitor therapy for rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disorder characterized by inflammation involving large and small joints. Systemic manifestations as well as involvement of paraoral tissues contribute to morbidity. Tumor necrosis factor (TNF) plays a central role in RA by amplifying inflammation in multiple pathways that lead to joint destruction. Tumor necrosis factor inhibitors were first licensed for clinical use in 1998; 3 have been approved for the treatment of RA: Iinfliximab, etanercept, and adalimumab. The purpose of this paper is to review the pathogenesis of RA, the state of the art of therapy, and the most current information on the safety and efficacy of TNF inhibitors for treatment of RA.

Mycobacterial and other serious infections in patients receiving anti-tumor necrosis factor and other newly approved biologic therapies: case finding through the Emerging Infections Network

We present the results of a nationwide survey of infectious disease consultants to identify mycobacterial and other serious infections in patients receiving anti-tumor necrosis factor compounds and other novel targeted therapies. Nontuberculous mycobacterial infections, histoplasmosis, and invasive Staphylococcus aureus infection were all reported more frequently than was tuberculosis disease in this context.

Comorbidities in rheumatoid arthritis

Rheumatoid arthritis (RA) is often characterized by the burden of swollen joints, pain, and decreased physical function, but less understood are the many manifestations of additional health conditions that are associated with RA and its treatments. First brought to light with observations of increased mortality in RA, studies noted the increased rates of cardiovascular and infection events. The chronic, debilitating, autoimmune nature of RA affects the patient directly or indirectly in almost all organ systems, from cardiovascular problems and infections to depression and gastrointestinal ulcers. On average, the established RA patient has two or more comorbid conditions. It should be the responsibility of the rheumatologist to take these and the risk of additional conditions into account when treating the patient. This chapter reviews important comorbidities in patients with RA, their prevalence, and their relation to RA.

Review article: minimizing tuberculosis during anti-tumour necrosis factor-alpha treatment of inflammatory bowel disease

BACKGROUND

Tumour necrosis factor (TNF)-alpha inhibitors are a major advance in the management of inflammatory bowel disease but increase the risk for tuberculosis (TB).

AIM

To examine the reasons for the increase in the risk for TB and the strategies to reduce it.

METHODS

PubMed searches were performed using search terms that included TB and each of the current anti-TNF-alpha biological agents and also TB and Crohn's disease.

RESULTS

Increased susceptibility to TB, often with extrapulmonary or disseminated disease, occurs following treatment with all anti-TNF-alpha biological agents and amounts to a four- to 20-fold increased risk with infliximab. TB usually occurs shortly after anti-TNF-alpha initiation suggesting reactivation of latent infection. Animal studies show that TNF-alpha inhibition impairs inflammatory cell trafficking and granuloma formation. Currently recommended screening for latent TB typically, risk assessment, tuberculin skin testing and chest radiograph used prior to anti-TNF-alpha treatment can reduce TB rates by up to 90% but newer screening interferon gamma assays may enhance screening efficacy. Patients positive on screening who are treated with isoniazid and subsequently receive anti-TNF-alpha treatment still have approximately 19% risk for TB.

CONCLUSIONS

Tuberculosis following treatment with TNF-alpha inhibitors usually results from reactivation of latent disease. Screening reduces the risk substantially but does not completely eliminate it.

Tumor necrosis factor blockade: mechanism of action

Modulation of the immune response with tumor necrosis factor (TNF) blockers is not a new treatment strategy for many inflammatory disorders; however, relatively little is known about their specific mechanism of action. Understanding the mode of action, pharmacology, and pharmacokinetics of the monoclonal TNF antibodies, infliximab and adalimumab, and the soluble TNF receptor, etanercept, may therefore enable us to account for their differing clinical profiles. The aim of this supplement is to explore the roles and mechanisms of TNF and TNF blockade using in vitro pharmacological and in vivo animal modeling experiments, and in vivo studies of the effects of etanercept on the inflammatory cascade in patients with psoriasis.

Serious infections with antirheumatic therapy: are biologicals worse?

This paper reviews the current evidence for the role of antirheumatic therapy in the development of serious infections in patients with rheumatoid arthritis (RA). Prednisone is clearly associated with increased infectious risk, but no definitive data link methotrexate to infection. Emerging data suggest that biological agents also pose increase infectious risk, particularly when used in combination with corticosteroids or methotrexate. Further research is needed in this important aspect of RA treatment. In the meantime, the author recommends that physicians should remain vigilant for serious infections in their patients with RA and use appropriate vaccines and screening procedures to mitigate their risk.

Inhibition of anti-tuberculosis T-lymphocyte function with tumour necrosis factor antagonists

Reactivation of latent Mycobacterium tuberculosis (Mtb) infection is a major complication of anti-tumour necrosis factor (TNF)-α treatment, but its mechanism is not fully understood. We evaluated the effect of the TNF antagonists infliximab (Ifx), adalimumab (Ada) and etanercept (Eta) on anti-mycobacterial immune responses in two conditions: with ex vivo studies from patients treated with TNF antagonists and with the in vitro addition of TNF antagonists to cells stimulated with mycobacterial antigens. In both cases, we analysed the response of CD4⁺ T lymphocytes to purified protein derivative (PPD) and to culture filtrate protein (CFP)-10, an antigen restricted to Mtb. The tests performed were lymphoproliferation and immediate production of interferon (IFN)-γ. In the 68 patients with inflammatory diseases (rheumatoid arthritis, spondylarthropathy or Crohn's disease), including 31 patients with a previous or latent tuberculosis (TB), 14 weeks of anti-TNF-α treatment had no effect on the proliferation of CD4⁺ T lymphocytes. In contrast, the number of IFN-γ-releasing CD4⁺ T lymphocytes decreased for PPD (p < 0.005) and CFP-10 (p < 0.01) in patients with previous TB and for PPD (p < 0.05) in other patients (all vaccinated with Bacille Calmette-Guérin). Treatments with Ifx and with Eta affected IFN-γ release to a similar extent. In vitro addition of TNF antagonists to CD4⁺ T lymphocytes stimulated with mycobacterial antigens inhibited their proliferation and their expression of membrane-bound TNF (mTNF). These effects occurred late in cultures, suggesting a direct effect of TNF antagonists on activated mTNF⁺ CD4⁺ T lymphocytes, and Ifx and Ada were more efficient than Eta. Therefore, TNF antagonists have a dual action on anti-mycobacterial CD4⁺ T lymphocytes. Administered in vivo, they decrease the frequency of the subpopulation of memory CD4⁺ T lymphocytes rapidly releasing IFN-γ upon challenge with mycobacterial antigens. Added in vitro, they inhibit the activation of CD4⁺ T lymphocytes by mycobacterial antigens. Such a dual effect may explain the increased incidence of TB in patients treated with TNF antagonists as well as possible differences between TNF antagonists for the incidence and the clinical presentation of TB reactivation.

Risk and prevention of tuberculosis and other serious opportunistic infections associated with the inhibition of tumor necrosis factor

Tumor necrosis factor (TNF) is a proinflammatory cytokine that has a key role in the pathogenesis of a variety of autoimmune diseases-including rheumatoid arthritis-and is an important constituent of the human immune response to infection. At present, three anti-TNF agents are approved (in the US and elsewhere) to treat selected autoimmune diseases: infliximab, etanercept, and adalimumab. These biologic agents have been associated with a variety of serious and 'routine' opportunistic infections; however, differences exist in the mechanisms of action of these agents that might confer variation in their associated risks of infection. From a public-health standpoint, the development of active tuberculosis in some patients who receive anti-TNF therapy is a matter of serious concern. Tuberculosis in such patients frequently presents as extrapulmonary or disseminated disease, and clinicians should be vigilant for tuberculosis in any patient taking anti-TNF therapy who develops fever, weight loss, or cough. To prevent the reactivation of latent tuberculosis infection during anti-TNF therapy, clinicians should screen all patients for tuberculosis, and begin treatment if latent infection is found, before anti-TNF therapy is initiated. Specific tuberculosis screening and treatment strategies vary between geographical regions and are reviewed in this document. The screening strategies employed in Europe and North America have reduced the occurrence of anti-TNF-associated tuberculosis and are clearly to be recommended, but the role of screening in the prevention of other opportunistic (e.g. fungal) infections is far less certain.

Abatacept treatment does not exacerbate chronicMycobacterium tuberculosis infection in mice

OBJECTIVE

Treatment of rheumatoid arthritis and other autoimmune disorders with anti-tumor necrosis factor (anti-TNF) agents is associated with an increased risk of reactivation of latent Mycobacterium tuberculosis. While the mechanism of action of abatacept is fundamentally different from that of anti-TNF therapies, its effect on the protective response to latent tuberculosis is not known. We undertook this study to determine the effect of abatacept treatment in a murine model of chronic M tuberculosis infection.

METHODS

Chronic M tuberculosis infection was established in C57BL/6 mice. Four months after infection, mice were treated for up to 16 weeks with abatacept, anti-murine TNF antibody, or vehicle. The primary end point was survival; body weight, bacterial load, histologic features, interferon-gamma (IFNgamma) production by T cells, and cellular infiltration were also assessed.

RESULTS

Abatacept- and vehicle-treated groups both maintained control of M tuberculosis infection, with 100% survival after 16 weeks of treatment. These 2 groups had no significant differences in body weight, no clinically relevant differences in bacterial load in the lungs, lymph nodes, or spleen, and no differences in the mean percentage of total or activated T cells, macrophages, neutrophils, or B cells, or in IFNgamma production in the lung or lymph nodes. In contrast, 100% mortality was seen in the anti-TNF antibody-treated group by week 9, with significant body weight loss and increased bacterial load in the lungs, lymph nodes, and spleen. Furthermore, the anti-TNF antibody-treated group had increased pathology consistent with the exacerbation of M tuberculosis infection.

CONCLUSION

Abatacept did not impair the ability of mice to control a chronic M tuberculosis infection. In contrast, mice treated with anti-TNF therapy showed increased pathology and bacterial load, with 100% mortality by week 9. The clinical significance of these findings has not yet been determined.

Safety of infliximab and other biologic agents in the inflammatory bowel diseases

In many ways, infliximab has drastically altered expectations for medical therapy in IBD, and it is expected that adalimumab and certolizumab pegol with ultimately have a similar role. Patients initiating such therapy should be made cognizant of the potential risks of serious infection including opportunistic ones, such as TB and histoplasmosis; demyelinating disorders; CHF; and lymphoma. Proper selection of candidates for anti-TNF-alpha therapy is critical in maintaining a proper benefit-to-risk ratio.