Rituximab for rheumatoid arthritis refractory to anti–tumor necrosis factor therapy: Results of a multicenter, randomized, double-blind, placebo-controlled, phase III trial evaluating primary efficacy and safety at twenty-four weeks

UK cost-utility analysis of rituximab in patients with rheumatoid arthritis that failed to respond adequately to a biologic disease-modifying antirheumatic drug

OBJECTIVE

To evaluate the incremental cost effectiveness of rituximab in patients with rheumatoid arthritis that failed to respond adequately to tumour necrosis factor-alpha inhibitors (biologic disease-modifying antirheumatic drugs; bDMARDs). A cost-utility model has been developed to simulate the long-term incremental cost and benefits of rituximab using data from clinical trials and registries.

METHODS

The model estimates the lifetime disease progression of up to 10,000 hypothetical rheumatoid arthritis (RA) patients that failed one bDMARD. It compares cost and outcomes of two treatment sequences, representing the current UK standard both with and without rituximab. The population characteristics match those of the Randomised Evaluation of Long-term Efficacy of rituximab in RA (REFLEX) phase III randomised control trial. Clinical outcomes were based on an indirect comparison of published American College of Rheumatology response rates, adjusted for differences in placebo. To estimate medical resource use, health assessment questionnaire (HAQ) scores were grouped into five categories with UK registry data informing the average cost for each category. Quality-adjusted life years (QALYs) gained were mapped from disease severity (HAQ scores).

RESULTS

Compared to a standard UK treatment sequence (assuming the sequential use of bDMARDs) the introduction of rituximab led to a QALY gain of 0.526 years. The incremental cost-effectiveness ratios (ICERs) based on total direct medical cost were 11,601 pounds. Adding rituximab to a treatment sequence with no sequential use of biologic generates an ICER of 14,690 pounds.

CONCLUSION

Rituximab has lower average annual treatment costs compared to other bDMARDs and is a highly cost-effective treatment option for patients who have failed to respond adequately to one bDMARD. The cost per QALY gained of rituximab falls well below commonly accepted thresholds within the UK. Potential weaknesses of the model include the paucity of data on the efficacy of bDMARDs or non-biologic DMARDs when used as second-line options; the lack of consensus about the most appropriate therapy in patients who fail all available bDMARDs; probable underestimation of the non-drug related medical costs; indirect measurement of QALY gains with rituximab therapy; and the necessity of synthesising data from a number of clinical trials with different populations and study drugs.

Translating basic research into clinical rheumatology

Findings from basic research in combination with precise clinical observations of the disease course in rheumatoid arthritis (RA) have led to the development of a multistage model to explain the pathophysiology of RA. Different cellular and soluble mediators, which play principal roles at different phases of the disease, have been identified. New therapeutic agents, which specifically target these factors, now allow us to intervene at several levels of the pathogenesis. This has already resulted in significant improvements for patients suffering from RA, and the development of new promising agents continues at a high pace. However, many questions concerning the optimal use of the new therapies remain unanswered. Combined efforts of basic research and clinical trials investigating the optimal timing and combination of the new treatments will be necessary to allow them to achieve their full potential and to result in the maximum benefit for patients.

Complement activation on B lymphocytes opsonized with rituximab or ofatumumab produces substantial changes in membrane structure preceding cell lysis

Binding of the CD20 mAb rituximab (RTX) to B lymphocytes in normal human serum (NHS) activates complement (C) and promotes C3b deposition on or in close proximity to cell-bound RTX. Based on spinning disk confocal microscopy analyses, we report the first real-time visualization of C3b deposition and C-mediated killing of RTX-opsonized B cells. C activation by RTX-opsonized Daudi B cells induces rapid membrane blebbing and generation of long, thin structures protruding from cell surfaces, which we call streamers. Ofatumumab, a unique mAb that targets a distinct binding site (the small loop epitope) of the CD20 Ag, induces more rapid killing and streaming on Daudi cells than RTX. In contrast to RTX, ofatumumab promotes streamer formation and killing of ARH77 cells and primary B cells from patients with chronic lymphocytic leukemia. Generation of streamers requires C activation; no streaming occurs in media, NHS-EDTA, or in sera depleted of C5 or C9. Streamers can be visualized in bright field by phase imaging, and fluorescence-staining patterns indicate they contain membrane lipids and polymerized actin. Streaming also occurs if cells are reacted in medium with bee venom melittin, which penetrates cells and forms membrane pores in a manner similar to the membrane-attack complex of C. Structures similar to streamers are demonstrable when Ab-opsonized sheep erythrocytes (non-nucleated cells) are reacted with NHS. Taken together, our findings indicate that the membrane-attack complex is a key mediator of streaming. Streamer formation may, thus, represent a membrane structural change that can occur shortly before complement-induced cell death.

Anti-CD20 therapy in patients with rheumatoid arthritis: predictors of response and B cell subset regeneration after repeated treatment

OBJECTIVE

B cell depletion with the anti-CD20 antibody rituximab has proven efficacy in patients with rheumatoid arthritis (RA). The effects on B cell homeostasis after repeated treatments and the relationship of certain B cell subsets to clinical response or relapse are currently not known.

METHODS

In this open-label study, 17 patients with RA refractory to standard therapy were treated with 1 cycle of rituximab. Of these 17 patients, 11 received a second cycle of rituximab therapy. Immunophenotyping was performed before therapy and during B cell recovery.

RESULTS

Twelve of 17 patients showed a good European League Against Rheumatism response after receiving 1 cycle of rituximab therapy. At the time of B cell recovery, the IgD+,CD27+ memory B cell subset was significantly larger (P = 0.019) in the nonresponder group. Within the group of 12 responders, 6 patients, whose disease was characterized by a significantly higher proportion of overall CD27+ memory B cells before therapy, experienced an early relapse (weeks 24-40 posttreatment). Eleven patients were re-treated, again resulting in a good clinical response. B cell reconstitution followed a similar pattern after each cycle. The early reconstitution phase was characterized by immature CD38++,IgD+,CD10+ B cells, whereas the number of naive B cells increased continuously thereafter. The number of memory B cells was still reduced at the time of the second depletion but recovered to levels similar to those following the first cycle of therapy.

CONCLUSION

Data derived from repeated B lymphocyte depletion with rituximab in patients with RA suggest that analysis of certain memory B cell subsets provides information on efficacy, response, and late as well as early relapse, consistent with the conclusion that targeting memory B cells is a key to its mechanism of action.

Improvement in patient-reported outcomes in a rituximab trial in patients with severe rheumatoid arthritis refractory to anti-tumor necrosis factor therapy

OBJECTIVE

To assess the effects of treatment with rituximab plus methotrexate on patient-reported outcomes in patients with active rheumatoid arthritis (RA) who experienced inadequate response to anti-tumor necrosis factor therapy.

METHODS

Patients with active RA were randomly assigned to rituximab (1,000 mg on days 1 and 15) or placebo. The primary end point was the proportion of patients with an American College of Rheumatology 20% response at week 24. Additional goals were to assess treatment effects on pain, fatigue, functional disability, health-related quality of life, and disease activity by comparing mean changes between groups. The analysis was conducted in the intent-to-treat population. The proportion of patients who achieved the minimum clinically important difference on the Health Assessment Questionnaire (HAQ) disability index (DI), Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F), and Short Form 36 (SF-36) was determined.

RESULTS

Rituximab patients had statistically significantly greater pain relief. The FACIT-F showed significantly greater improvement in rituximab patients than placebo patients from weeks 12 through 24. Mean improvement from baseline in functional disability (measured by the HAQ DI) was significantly greater in rituximab patients from weeks 8 to 24. The mean +/- SD change from baseline for the SF-36 Physical Component Score was 6.64 +/- 8.74 for rituximab patients and 1.48 +/- 7.32 for placebo patients (P < 0.0001). The mean change from baseline for the SF-36 Mental Component Score was 5.32 +/- 12.41 for rituximab patients and 2.25 +/- 12.23 for placebo patients (P = 0.0269).

CONCLUSION

Rituximab produced rapid, clinically meaningful, and statistically significant improvements in patient-reported pain, fatigue, functional disability, health-related quality of life, and disease activity. These effects were sustained throughout the study.

Fully human antibodies from transgenic mouse and phage display platforms

Over the past two decades, technologies have emerged for generating monoclonal antibodies (MAbs) derived from human immunoglobulin gene sequences. These fully human MAbs provide an alternative to re-engineered, or de-immunized, rodent MAbs as a source of low immunogenicity therapeutic antibodies. There are now two marketed fully human therapeutic MAbs, adalimumab and panitumumab, and several dozen more in various stages of human clinical testing. Most of the drugs, including adalimumab and panitumumab, were generated using either phage display or transgenic mouse platforms. The reported clinical experience with fully human MAbs demonstrates that these two platforms are, and should continue to be, a significant source of active and well tolerated experimental therapeutics. While this body of reported clinical data does not yet provide a clear distinction between the platforms, the available descriptions of the drug discovery processes used to identify the clinical candidates highlight one difference. It appears that lead optimization is more commonly applied to phage display derived leads than transgenic mouse derived leads.

IL-6 receptor inhibition with tocilizumab improves treatment outcomes in patients with rheumatoid arthritis refractory to anti-tumour necrosis factor biologicals: results from a 24-week multicentre randomised placebo-controlled trial

Objectives:

The phase III RADIATE study examined the efficacy and safety of tocilizumab, an anti-IL-6 receptor monoclonal antibody in patients with rheumatoid arthritis (RA) refractory to tumour necrosis factor (TNF) antagonist therapy.

Methods:

499 patients with inadequate response to one or more TNF antagonists were randomly assigned to receive 8 mg/kg or 4 mg/kg tocilizumab or placebo (control) intravenously every 4 weeks with stable methotrexate for 24 weeks. ACR20 responses, secondary efficacy and safety endpoints were assessed.

Results:

ACR20 was achieved at 24 weeks by 50.0%, 30.4% and 10.1% of patients in the 8 mg/kg, 4 mg/kg and control groups, respectively (less than p<0.001 both tocilizumab groups versus control). At week 4 more patients achieved ACR20 in 8 mg/kg tocilizumab versus controls (less than p = 0.001). Patients responded regardless of most recently failed anti-TNF or the number of failed treatments. DAS28 remission (DAS28 <2.6) rates at week 24 were clearly dose related, being achieved by 30.1%, 7.6% and 1.6% of 8 mg/kg, 4 mg/kg and control groups (less than p = 0.001 for 8 mg/kg and p = 0.053 for 4 mg/kg versus control). Most adverse events were mild or moderate with overall incidences of 84.0%, 87.1% and 80.6%, respectively. The most common adverse events with higher incidence in tocilizumab groups were infections, gastrointestinal symptoms, rash and headache. The incidence of serious adverse events was higher in controls (11.3%) than in the 8 mg/kg (6.3%) and 4 mg/kg (7.4%) groups.

Conclusion:

Tocilizumab plus methotrexate is effective in achieving rapid and sustained improvements in signs and symptoms of RA in patients with inadequate response to TNF antagonists and has a manageable safety profile.

Trial registration number:

NCT00106522.

Malignancy and biologic therapy in rheumatoid arthritis

PURPOSE OF REVIEW

Owing to the complex functions of the inflammatory response systems--potentially or clearly of importance in human carcinogenesis--that biological therapies interfere with uncertainty regarding their safety profile for malignancy is more or less expected. This uncertainty has been further sparked by the apparent discordance between trial data and observational studies of anti-TNF agents, and the methodological challenges inherent in addressing the safety profile of new drugs for delayed and multifactorial events like cancer.

RECENT FINDINGS

This review provides a summary of the pattern of cancer seen in patients with rheumatoid arthritis not treated with biologics, and the currently published data on cancer risk following treatment with biologics in patients with rheumatoid arthritis, primarily anti-TNF therapy.

SUMMARY

Published data currently do not exclude clinically important increased risks, nor do they refute beneficial effects. As per definition, much of the currently available safety data from trials or clinical practice do not capture the impact of either any effect that biological therapy might have on early events in carcinogenesis, or of sustained exposure to biologics. Beyond the risk of de-novo cancer development, several other clinically important aspects of cancer safety remain to be addressed, including issues of prognosis, progression, and relapse.

Selective costimulation modulation with abatacept: a look at quality-of-life outcomes in patients with rheumatoid arthritis

OBJECTIVES

To highlight the importance of improving quality of life (QoL) in patients with rheumatoid arthritis (RA) and to provide a summary of the QoL benefits provided by abatacept in patients who have an inadequate response to disease-modifying antirheumatic drugs (DMARDs) and/or tumor necrosis factor (TNF) antagonists.

METHODS

A literature search of the MEDLINE, EMBASE, and BIOSIS databases was performed using the terms "abatacept," "cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4)" and "ORENCIA," with the coindexing terms: "abatacept," "CTLA-4," and "ORENCIA." Only articles presenting primary data on QoL outcomes from randomized, placebo-controlled clinical trials of abatacept were included in the review.

RESULTS

The literature search initially yielded 220 articles. A total of 8 articles fulfilled the inclusion criteria described above and are reviewed here. In clinical trials to date, abatacept treatment has been shown to improve QoL in patients who have an inadequate response to traditional DMARDs and TNF antagonists.

CONCLUSIONS

Improvements in QoL are rated by patients as 1 of the most important benefits of an effective treatment; however, inclusion of QoL measurements in clinical trials as a measure of efficacy is a relatively recent event. Abatacept has been shown to alleviate both the physical and the emotional/social burdens that RA imposes on the patient, including improvements in day-to-day activity and reducing sleep problems and fatigue in patients with RA who have an inadequate response to DMARDs and/or TNF antagonists.

Improvements in clinical response between 12 and 24 weeks in patients with rheumatoid arthritis on etanercept therapy with or without methotrexate

Background:

Whereas many patients respond quickly to treatment with tumour necrosis factor (TNF) inhibitors, some patients may experience significant but delayed responses.

Objective:

To evaluate the clinical response between 12 and 24 weeks in subjects with rheumatoid arthritis from the Trial of Etanercept and Methotrexate with Radiographic Patient Outcomes.

Methods:

Clinical response was assessed at 24 weeks in 12-week non-responders, according to American College of Rheumatology (ACR) response criteria. The proportion of subjects who successfully maintained response to 52 weeks was analysed, as were radiographic outcomes.

Results:

Data from 682 subjects were included in the analysis. Non and partial responders in all three groups (etanercept, methotrexate and etanercept plus methotrexate) at week 12 showed an improvement in responses at week 24. Over 80% of the week 24 ACR20/50/70 responders in the etanercept plus methotrexate arm sustained their response to 52 weeks. In the etanercept arms, a delayed clinical response was not associated with increased radiographic progression at week 52.

Conclusion:

A significant proportion of non and partial responders to etanercept with or without methotrexate therapy at week 12 achieved a good clinical response or improved their overall clinical response at week 24. Discontinuing TNF inhibitor therapy at 12 weeks may be premature in some rheumatoid arthritis patients.

Biological therapies for the treatment of juvenile idiopathic arthritis: Lessons from the adult and pediatric experiences

Biologics have advanced the therapy of adult and pediatric arthritis. They have been linked to rare serious adverse outcomes, but the actual risk of these events is controversial in adults, and largely unknown in pediatrics. Because of the paucity of safety and efficacy data in children, pediatric rheumatologists often rely on the adult literature. Herein, we reviewed the adult and pediatric literature on five classes of medicines: Tumor necrosis factor (TNF) inhibitors, anakinra, rituximab, abatacept, and tocilizumab. For efficacy, we reviewed randomized controlled studies in adults, but did include lesser qualities of evidence for pediatrics. For safety, we utilized prospective and retrospective studies, rarely including reports from other inflammatory conditions. The review included studies on rheumatoid arthritis and spondyloarthritis, as well as juvenile idiopathic arthritis. Overall, we found that the TNF inhibitors have generally been found safe and effective in adult and pediatric use, although risks of infections and other adverse events are discussed. Anakinra, rituximab, abatacept, and tocilizumab have also shown positive results in adult trials, but there is minimal pediatric data published with the exception of small studies involving the subgroup of children with systemic onset juvenile idiopathic arthritis, in whom anakinra and tocilizumab may be effective therapies.

Rituximab in relapsing-remitting multiple sclerosis: a 72-week, open-label, phase I trial

We evaluated the safety, tolerability, pharmacodynamics, and activity of B-cell depletion with rituximab in patients with relapsing-remitting multiple sclerosis, receiving two courses of rituximab 6 months apart, and followed for a total of 72 weeks. No serious adverse events were noted; events were limited to mild-to-moderate infusion-associated events, which tended to decrease with subsequent infusions. Infections were also mild or moderate, and none led to withdrawal. Fewer new gadolinium-enhancing or T2 lesions were seen starting from week 4 and through week 72. An apparent reduction in relapses was also observed over the 72 weeks compared with the year before therapy.

Treating multiple sclerosis with monoclonal antibodies

Therapeutic monoclonal antibodies (mAbs) are potent new tools for a molecular targeted approach to modify the course of multiple sclerosis (MS). Besides natalizumab, which was approved in 2006, three other mAbs (alemtuzumab, rituximab and daclizumab) were successfully tested in Phase II MS trials. In this review, introductory notes on the development and systematic nomenclature of therapeutic mAbs in general, set the stage for a detailed discussion of the four mAbs mentioned. We summarize non-MS indications, expression and function of target antigens, scientific rationales for MS therapy, putative modes of action and pharmacological aspects. Particularly, we provide a critical discussion of clinical MS trials, including protocols and interim analyses of trials currently underway. The natalizumab section pays special attention to the clinical handling of safety issues and the diagnostic use of neutralizing antibodies. We finally develop a scenario for how each of the four mAbs might evolve into the market of MS therapeutics within the coming years.

Rheumatoid arthritis: beyond tumor necrosis factor-alpha antagonists, B cell depletion, and T cell blockade

Significant advances have been made in the treatment of rheumatoid arthritis (RA). For instance, novel biologic therapeutics capable of blocking tumor necrosis factor-alpha (TNF-alpha) have improved outcomes for RA patients. New therapeutic agents directed at antagonizing two previously untargeted pathways have recently been approved by the U.S. Food and Drug Administration for RA patients who have had inadequate responses to anti-TNF therapy or who have failed to maintain an adequate clinical response. We review the data supporting the use of these agents, rituximab and abatacept.

The future of the IL-1 receptor antagonist anakinra: from rheumatoid arthritis to adult-onset Still's disease and systemic-onset juvenile idiopathic arthritis

BACKGROUND

IL-1 receptor antagonist (IL-1Ra) is a naturally occurring IL-1RI-binding molecule that blocks the biologic effects of the proinflammatory cytokine IL-1. A recombinant form of human IL-1Ra, anakinra (Kineret), has been approved for use in rheumatology initially to manage rheumatoid arthritis (RA) patients that are refractory to more conventional forms of treatment.

OBJECTIVE

This review summarizes the experience with anakinra in the treatment of patients with rheumatic diseases emphasizing its beneficial effects in novel applications.

METHODS

English-language trials of anakinra were searched using MEDLINE and abstracts from rheumatology scientific meetings.

RESULTS/CONCLUSIONS

In the treatment of patients with RA anakinra is effective but inferior to TNF-alpha blocking agents. Over the last few years it has become increasingly evident that anakinra is highly effective and safe in patients with systemic-onset juvenile idiopathic arthritis, adult-onset Still's disease, hereditary autoinflammatory syndromes, Schnitzler's syndrome and recently in gouty attacks.

Safety of biologic therapy in rheumatoid arthritis and other autoimmune diseases: focus on rituximab

OBJECTIVES

To review the safety of biologic agents used to treat rheumatoid arthritis (RA) and other autoimmune diseases, with a focus on rituximab.

METHODS

Information was gathered from a search of the PubMed database and from major congress abstract listings through June 2007.

RESULTS

Rituximab is approved for treating RA in patients with an inadequate response to TNF inhibitors and is under study in other indications for RA and other autoimmune disorders. The current safety profile of rituximab in RA is known from Phase II and III studies conducted preapproval, treating approximately 750 patients, as well as from long-term extension studies with repeated therapy. Clinical trials have established that the most common adverse events are infusion-associated reactions, seen in 29 to 40% of patients, most of which are mild to moderate and occur following the first rituximab infusion, with incidence and severity decreasing with subsequent infusions. Rates of infections and serious infections to date are within the range expected for RA patients treated with other biologic agents, but the longer term effects of B-cell depletion and the effects of repeated treatment on the risk of infections are uncertain. Information is limited for rituximab safety in other autoimmune disorders but current data do not suggest that there is a significant difference in adverse events from that previously reported.

CONCLUSIONS

Rituximab is an important addition to the rheumatologist's armamentarium for the treatment of difficult RA and ongoing trials will determine its utility in other indications for RA and other autoimmune conditions. The true safety profile of rituximab will emerge as larger numbers of patients are treated in routine clinical practice.

Treatment of hepatitis C-associated mixed cryoglobulinemia vasculitis

PURPOSE OF REVIEW

Hepatitis C virus infection is the main cause of mixed cryoglobulinemia vasculitis. The disease expression of mixed cryoglobulinemia vasculitis is variable, ranging from mild clinical symptoms (purpura, arthralgia) to fulminant life-threatening complications (glomerulonephritis, widespread vasculitis). Treatment of hepatitis C virus-mixed cryoglobulinemia vasculitis may target either the viral trigger (hepatitis C virus) or the downstream B-cell arm of autoimmunity. This review focuses on recent advances in our understanding of the treatment of hepatitis C virus-mixed cryoglobulinemia vasculitis.

RECENT FINDINGS

Aggressive antiviral therapy with Peg-IFNalpha and ribavirin should be considered as induction therapy for hepatitis C virus-mixed cryoglobulinemia vasculitis with mild to moderate disease severity and activity. In patients presenting with severe disease, an induction phase of immunosuppression is often necessary while awaiting the generally slow response to antiviral treatments. Combination therapy with rituximab and Peg-IFNalpha plus ribavirin appears logical as it may target both the viral trigger (hepatitis C virus) and cryoglobulin-producing B-cells.

SUMMARY

Antiviral therapy and rituximab are the main therapeutic options in hepatitis C virus-mixed cryoglobulinemia vasculitis. Further studies are needed to better define the therapeutic strategy.

Targeted therapy in rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is the most common inflammatory joint disease in adults leading to pain and disability. New drugs, called biologicals, have opened up new possibilities in the treatment of RA.

OBJECTIVE

Targeting pro-inflammatory cytokines such as tumour necrosis factor-α (TNF-α) or interleukin-1 (IL-1) is well established in clinical care of RA patients. However, lack or loss of clinical response occurs in up to 25% of the patients. New strategies beyond these targets, namely blocking T cells by abatacept or B cells by rituximab (RTX), have been introduced recently.

METHODS

All relevant clinical trials published in peer-reviewed journals are discussed in this article. Data from abstracts presented at congresses have not been included.

CONCLUSION

TNF blocking agents have significantly improved therapy of and outcome in RA patients and, therefore, are still the first choice biologicals for the treatment of RA. Alternatively, abatacept or RTX offer new options in case of inefficacy of or contraindications against anti-TNF therapy. Forthcoming drugs, such as tocilizumab, will extend our armamentarium to treat RA effectively.

Rituximab therapy for refractory biliary strictures in immunoglobulin G4-associated cholangitis

BACKGROUND & AIMS

Biliary strictures occur in a third of patients with autoimmune pancreatitis and have been termed immunoglobulin G subclass 4 (IgG4) associated cholangitis (IAC). IAC often responds to steroid therapy.

METHODS

A patient with autoimmune pancreatitis and (IAC) refractory to steroids and 6-mercaptopurine was treated with rituximab, a monoclonal antibody directed against the CD20 antigen on B lymphocytes.

RESULTS

The patient's biliary strictures improved after rituximab therapy, permitting removal of his biliary stents. Systemic manifestations of IgG4-associated disease also improved.

CONCLUSIONS

Rituximab may be a treatment option for patients with refractory or recurrent autoimmune pancreatitis or IAC.

Pharmacokinetics and biological activity of atacicept in patients with rheumatoid arthritis

Atacicept is a recombinant fusion protein containing the extracellular ligand-binding portion of the transmembrane activator and CAML interactor (TACI, CD267) receptor and inhibits B lymphocyte stimulator (BLyS, CD257) and a proliferation-inducing ligand (APRIL, CD256), both potent stimulators of B cell maturation, proliferation, and survival. Atacicept pharmacokinetics and pharmacodynamics were assessed in a double-blind, placebo-controlled, phase I study in patients with active, moderate to severe rheumatoid arthritis receiving atacicept either as a single subcutaneous or repeated, every other week dose. Pharmacokinetic profiles were determined by measuring serum concentrations of free atacicept and its complex with BLyS. Nonspecific immunoglobulin (Ig)M, IgG, and IgA; IgM-RF (rheumatoid factor), IgG-RF, and IgA-RF antibody levels; and B cell profiles provided markers of biological activity. Pharmacokinetic, biological activity, and relationships between atacicept dose and Ig antibody response were evaluated. Pharmacokinetic profiles of atacicept were nonlinear, influenced by saturable binding with its ligands, but were consistent and predictable. Atacicept treatment reduced Ig and RF serum concentration. IgM antibody levels were most sensitive to atacicept, followed by IgA and IgG, underlining the biological activity of atacicept in patients with rheumatoid arthritis. These findings can be used to explore dosing regimen design scenarios in future studies.

B-cell depletion with rituximab in relapsing-remitting multiple sclerosis

BACKGROUND

There is increasing evidence that B lymphocytes are involved in the pathogenesis of multiple sclerosis, and they may be a therapeutic target. Rituximab, a monoclonal antibody, selectively targets and depletes CD20+ B lymphocytes.

METHODS

In a phase 2, double-blind, 48-week trial involving 104 patients with relapsing-remitting multiple sclerosis, we assigned 69 patients to receive 1000 mg of intravenous rituximab and 35 patients to receive placebo on days 1 and 15. The primary end point was the total count of gadolinium-enhancing lesions detected on magnetic resonance imaging scans of the brain at weeks 12, 16, 20, and 24. Clinical outcomes included safety, the proportion of patients who had relapses, and the annualized rate of relapse.

RESULTS

As compared with patients who received placebo, patients who received rituximab had reduced counts of total gadolinium-enhancing lesions at weeks 12, 16, 20, and 24 (P<0.001) and of total new gadolinium-enhancing lesions over the same period (P<0.001); these results were sustained for 48 weeks (P<0.001). As compared with patients in the placebo group, the proportion of patients in the rituximab group with relapses was significantly reduced at week 24 (14.5% vs. 34.3%, P=0.02) and week 48 (20.3% vs. 40.0%, P=0.04). More patients in the rituximab group than in the placebo group had adverse events within 24 hours after the first infusion, most of which were mild-to-moderate events; after the second infusion, the numbers of events were similar in the two groups.

CONCLUSIONS

A single course of rituximab reduced inflammatory brain lesions and clinical relapses for 48 weeks. This trial was not designed to assess long-term safety or to detect uncommon adverse events. The data provide evidence of B-cell involvement in the pathophysiology of relapsing-remitting multiple sclerosis. (ClinicalTrials.gov number, NCT00097188 [ClinicalTrials.gov].).

Rituximab for the treatment of rheumatoid arthritis

Rituximab has been approved by the United States Food and Drug Administration in combination with methotrexate for the treatment of rheumatoid arthritis in patients who failed to achieve adequate benefit from tumor necrosis factor-alpha inhibitors. Rituximab is a biologic agent that depletes peripheral B cells--an action thought to reduce rheumatoid arthritis activity--and induces prolonged clinical improvement. Two 1000-mg infusions administered 2 weeks apart can result in a response that lasts for months. Most patients will require retreatment, but the effect of repeated dosing on patient outcomes has not yet been determined. Combination therapy with methotrexate is recommended as this appears to achieve the best outcomes. Rituximab also has been shown to be safe, although the lack of long-term efficacy and safety data limit its use. More studies are needed, but this agent has been demonstrated to be safe and effective in patients who fail to achieve adequate clinical response to methotrexate and tumor necrosis factor-alpha inhibitors.

Biologic treatments for systemic rheumatic diseases

Many rheumatologic disorders, most notably Sjögren's syndrome, are associated with dental complications and in some cases oral diseases may trigger or drive connective tissue disease. During the past three decades the treatment in rheumatology was revolutionized by the introduction of disease-modifying anti-rheumatic drugs. Advances in our understanding of the pathogenesis of rheumatic diseases have led to the discovery of critical mechanisms of inflammation and autoimmunity and the invention of new target-specific biologic agents. In this review, we will summarize the current state of biologic therapies in rheumatology and discuss the implications of these on oral health and disease.

Histological analysis of synovium in cases of effect attenuation associated with infliximab therapy in rheumatoid arthritis

To investigate the histological changes of synovium in cases of effect attenuation occurring after the use of infliximab in the treatment of rheumatoid arthritis (RA), we histologically assessed synovial tissue from ten methotrexate-treated RA patients and 12 infliximab-treated RA patients after arthroscopic synovectomy. The synovium was observed using hematoxylin and eosin (H&E) stain and analyzed immunohistochemically for expression of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), matrix metalloproteinase-3 (MMP-3), B-cell transmembrane protein, cluster of differentiation 20 (CD20), nuclear factor kappa B (NFkB), bromodeoxyuridine (BrdU), and vascular endothelial growth factor (VEGF). H&E staining showed significant vascular proliferation in the synovium of the RA patients in the infliximab group (p < 0.05). Immunohistochemical examinations showed that TNF-alpha was completely blocked in patients with effect attenuation who received infliximab (p < 0.05). IL-6 was more strongly expressed in the interstitial cells of synovium of patients who received infliximab than in the cells of patients in the control group (p < 0.05). MMP-3 was expressed on the surface of synovium, and CD20 and BrdU were strongly expressed in the infliximab group compared with the control group (p < 0.05). NFkB was expressed in both groups. VEGF was decreased in the infliximab group compared with control. These findings indicate that the expression pattern of immunohistochemical findings in synovium was changed in effect attenuation cases among RA patients treated with infliximab.

Immunohistochemical analysis as a means to predict responsiveness to rituximab treatment

OBJECTIVE

Anti-CD20-mediated B cell depletion with rituximab is a new and effective therapy for rheumatoid arthritis (RA). Although B cells in peripheral blood (PB) are consistently depleted in all patients, the clinical effects are more heterogeneous, possibly related to differences in the depleting effects of lymphoid or solid tissues. The aim of this study was to investigate B cell depletion in different compartments (PB, bone marrow, and synovium) and determine predictive variables for responsiveness to rituximab therapy.

METHODS

Before and 12 weeks after rituximab treatment, samples of PB, bone marrow, and synovium were collected from 25 patients with RA refractory to disease-modifying antirheumatic drugs and tumor necrosis factor-blocking agents. CD19+ and CD20+ B cells in PB and bone marrow were measured by flow cytometric analysis, whereas CD79a+ and cytoplasmic CD20+ B cells in the synovium were stained by immunohistochemistry. The effects of rituximab on serum Ig and autoantibodies were measured by enzyme-linked immunosorbent assay.

RESULTS

Rituximab effectively depleted the CD20+ subset of B cells in the PB, bone marrow, and synovium of RA patients. Rituximab significantly reduced autoantibody production (anti-citrullinated protein antibodies [ACPAs] and rheumatoid factor [RF]), in part due to a nonspecific decrease in total Ig production. Importantly, positivity for circulating ACPA IgM, in combination with a high infiltration of CD79a+ B cells in the synovium, but not of CD138+ plasma cells, was a predictor of clinical outcome after rituximab treatment. ACPA IgM titers were independently associated with synovial infiltration of CD20-,CD79a+ B cells, but not with CD138+ plasma cells.

CONCLUSION

These data provide novel insights into the mechanisms of CD20-mediated B cell depletion in the lymphoid and solid tissues of RA patients and suggest a pivotal role for ACPA IgM-producing plasmablasts in RA.

Safety and efficacy of additional courses of rituximab in patients with active rheumatoid arthritis: an open-label extension analysis

OBJECTIVE

To determine the safety and efficacy of additional courses of rituximab in patients with rheumatoid arthritis (RA).

METHODS

An open-label extension analysis of RA patients previously treated with rituximab was conducted. Patients who had participated in any of 3 double-blind trials were eligible for additional courses (2 infusions of 1,000 mg given 2 weeks apart) if they exhibited a swollen joint count and tender joint count of > or =8 with > or =16 weeks elapsing after the previous course. Safety was assessed in patients receiving all or a portion of a rituximab course. Efficacy was assessed 24 weeks after each course, using the American College of Rheumatology 20% criteria for improvement (ACR20), ACR50, ACR70, European League Against Rheumatism (EULAR) response criteria, Disease Activity Score in 28 joints, the disability index of the Health Assessment Questionnaire, and Short Form 36 scores, stratified according to prior tumor necrosis factor (TNF) inhibitor exposure.

RESULTS

A total of 1,039 patients received > or =1 course of rituximab. Of these, 570 received 2 courses, 191 received 3 courses, and 40 received 4 courses, for a total of 1,669 patient-years. Irrespective of prior TNF inhibitor exposure, ACR20 responses were comparable at week 24 after course 1 and at week 24 after course 2 (65% versus 72%), as were ACR50 and ACR70 responses. EULAR moderate/good responses were also comparable in course 2 relative to course 1 (88% versus 79%), with EULAR remission occurring in a 2-fold higher proportion of patients after course 2 than after course 1 (13% versus 6%). The most common adverse events, which were mild-to-moderate acute infusion-related events, decreased with each course. The serious infection rate after course 1 (5.1 per 100 patient-years) remained stable through additional courses. The proportion of patients with circulating IgM and IgG levels below the lower limit of normal (LLN) increased with subsequent courses; however, serious infection rates in these patients (5.6 per 100 patient-years in patients with low IgM levels and 4.8 per 100 patient-years in patients with low IgG levels were comparable with those in patients with immunoglobulin levels above the LLN (4.7 per 100 patient-years). Patients with human antichimeric antibody (9.2%) did not exhibit decreasing efficacy or present additional safety concerns.

CONCLUSION

These findings indicate that patients treated with repeated courses of rituximab have sustained clinical responses with no new adverse events.

Risk of serious infections during rituximab, abatacept and anakinra treatments for rheumatoid arthritis: meta-analyses of randomised placebo-controlled trials

Background:

Tumour necrosis factor α blockers in rheumatoid arthritis are known to increase the risk of serious infections defined as life-threatening, requiring hospitalisation or intravenous antibiotics. Recently, new biological agents have become available. Their safety is an important issue.

Purpose:

To assess if biological agents, ie rituximab, abatacept and anakinra increase the risk of serious infections in patients with rheumatoid arthritis in published randomised controlled trials.

Data source:

A systematic review of the literature using PUBMED, EMBASE, Cochrane library and abstracts databases (American College of Rheumatology and European League Against Rheumatism annual meetings) was performed up to October 2007. This search was completed with data from the Food and Drug Administration, the European Agency for the Evaluation of Medicinal Products and manufacturers.

Data extraction:

Three fixed-effect meta-analyses were performed to compare serious infection rates between each biological agent and placebo. Pooled odds ratios (ORs) were calculated, using the Mantel–Haenszel method with a continuity correction.

Data synthesis:

Twelve randomised controlled trials with data concerning serious infections were analysed (three for rituximab, five for abatacept and four for anakinra). They included 745 patients, 1960 patients, 2062 patients and 2112 patients treated by rituximab, abatacept, anakinra and placebo respectively. The overall pooled ORs did not reveal a statistically significant increased risk of serious infection for abatacept and rituximab; this risk was increased for high doses of anakinra (⩾100 mg daily) versus low dose and placebo (ORs = 9.63 (95% CI, 1.31 to 70.91) and 3.40 (95% CI, 1.11 to 10.46) respectively).

Conclusions:

These meta-analyses did not reveal a significant increase in the risk of serious infections during rituximab or abatacept treatments in patients with rheumatoid arthritis; however, high doses of anakinra may increase this risk, especially when patients have comorbidity factors. Large studies must be performed to confirm this safety profile in daily practice.

B-cell inhibitors as therapy for rheumatoid arthritis: an update

A revolution in the treatment of rheumatoid arthritis has occurred in recent years. This holds particularly true for B-cell-directed therapies for rheumatoid arthritis. The approval of rituximab for the treatment of rheumatoid arthritis has not only expanded the armamentarium of therapies for rheumatologists, but it has also led the way to better understanding of the biologic sequelae of these treatments as well as the potential to better understand the etiology of autoimmune diseases. This review updates the latest B-cell therapies in rheumatoid arthritis.

B cells and autoantibodies in the pathogenesis of multiple sclerosis and related inflammatory demyelinating diseases

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS). The mainstream view is that MS is caused by an autoimmune attack of the CNS myelin by myelin-specific CD4 T cells, and this perspective is supported by extensive work in the experimental autoimmune encephalomyelitis (EAE) model of MS as well as immunological and genetic studies in humans. However, it is important to keep in mind that other cell populations of the immune system are also essential in the complex series of events leading to MS, as exemplified by the profound clinical efficacy of B cell depletion with Rituximab. This review discusses the mechanisms by which B cells contribute to the pathogenesis of MS and dissects their role as antigen-presenting cells (APCs) to T cells with matching antigen specificity, the production of proinflammatory cytokines and chemokines, as well as the secretion of autoantibodies that target structures on the myelin sheath and the axon. Mechanistic dissection of the interplay between T cells and B cells in MS may permit the development of B cell based therapies that do not require depletion of this important cell population.

Anti-CD20 monoclonal antibody in rheumatoid arthritis and systemic lupus erythematosus

Rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) are both chronic autoimmune rheumatic diseases. In the last few years, evolution in the understanding of RA and SLE pathogenesis and underlying molecular mechanisms has resulted in development and availability of novel therapies. In particular, the recent acknowledgement of a more significant role for B cells in the pathogenesis of RA, in contrast to the view that it was predominantly a T cell disorder, provided rationale for trials of B cell depletion therapy with the chimeric anti-CD20 monoclonal antibody rituximab. The efficacy and favourable safety profile of rituximab have resulted in the recent approval by the European Medicines Agency for its usage in patients with RA unresponsive to conventional therapies. The salient features from the pivotal open and randomised controlled trials are reviewed in this chapter. Given the recognition of B cell dysfunction as central to SLE pathogenesis, the use of anti-CD20 antibody therapy for this patient group has also been established. Results of the open trials have been encouraging, particularly in patients not responding to usual therapies, and a randomised controlled trial is underway.

Human monoclonal antibodies from transgenic mice

Since the 1986 regulatory approval of muromonomab-CD3, a mouse monoclonal antibody (MAb) directed against the T cell CD3epsilon antigen, MAbs have become an increasingly important class of therapeutic compounds in a variety of disease areas ranging from cancer and autoimmune indications to infectious and cardiac diseases. However, the pathway to the present acceptance of therapeutic MAbs within the pharmaceutical industry has not been smooth. A major hurdle for antibody therapeutics has been the inherent immunogenicity of the most readily available MAbs, those derived from rodents. A variety of technologies have been successfully employed to engineer MAbs with reduced immunogenicity. Implementation of these antibody engineering technologies involves in vitro optimization of lead molecules to generate a clinical candidate. An alternative technology, involving the engineering of strains of mice to produce human instead of mouse antibodies, has been emerging and evolving for the past two decades. Now, with the 2006 US regulatory approval of panitumumab, a fully human antibody directed against the epidermal growth factor receptor, transgenic mice expressing human antibody repertoires join chimerization, CDR grafting, and phage display technologies, as a commercially validated antibody drug discovery platform. With dozens of additional transgenic mouse-derived human MAbs now in clinical development, this new drug discovery platform appears to be firmly established within the pharmaceutical industry.

Abatacept inhibits progression of structural damage in rheumatoid arthritis: results from the long-term extension of the AIM trial

OBJECTIVE

Assess the effect of abatacept on progression of structural damage over 2 years in patients with rheumatoid arthritis who had an inadequate response to methotrexate.

METHODS

539 patients entered an open-label extension of the AIM (Abatacept in Inadequate responders to Methotrexate) trial and received abatacept. Radiographic assessment of the hands and feet was performed at baseline, year 1 and year 2. At year 2, each patient's radiographs were scored for progression blinded to sequence and treatment allocation.

RESULTS

In patients treated with abatacept for 2 years, greater reduction in progression of structural damage was observed in year 2 than in year 1. The mean change in total Genant-modified Sharp scores was reduced from 1.07 units in year 1 to 0.46 units in year 2. Similar reductions were observed in erosion and joint space narrowing scores. Following 2 years of treatment with abatacept, 50% of patients had no progression of structural damage as defined by a change in the total score of < or =0 compared with baseline. 56% of patients treated with abatacept had no progression during the first year compared with 45% of patients treated with placebo. In their second year of treatment with abatacept, more patients had no progression than in the first year (66% vs 56%).

CONCLUSIONS

Abatacept has a sustained effect that inhibits progression of structural damage. Furthermore, the mean change in radiographic progression in patients treated with abatacept for 2 years was significantly lower in year 2 versus year 1, suggesting that abatacept may have an increasing disease-modifying effect on structural damage over time.

A mechanistic perspective of monoclonal antibodies in cancer therapy beyond target-related effects

Several monoclonal antibodies are now in clinical use for cancer therapy, and many others are currently undergoing clinical evaluation. These agents offer unique specificity against key molecular targets on tumor cells or in the tumor microenvironment. The clinical efficacy of monoclonal antibodies is generally attributed to target-specific mechanisms resulting from neutralizing or inhibiting a growth factor or receptor that drives cell proliferation and tumor growth. Several targets, including CD20, human epidermal growth factor receptor 2, vascular endothelial growth factor, and epidermal growth factor receptor, have been validated in specific malignancies on the basis of monoclonal antibody efficacy. However, monoclonal antibodies also have the potential to activate immune-mediated effector functions, including antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity. These functions result from interactions involving the Fc domain of the antibody, and, consequently, may vary by antibody, isotype, and Fc modification, such as changes in glycosylation. Accordingly, all monoclonal antibodies directed against a given target should not be considered equivalent in their ability to stimulate immune-mediated effector functions.

The biology behind the new therapies for SLE

BACKGROUND

Systemic lupus erythematosus (SLE) is a heterogenous disease with complex pathogenesis.

AIM

In this review, we summarise recent progress in the understanding of SLE pathogenesis and discuss implications for the treatment of SLE patients using standard and experimental medications.

CONCLUSIONS

The discovery that Toll-like receptor signalling and interferon-alpha abundance are central elements of the disease process has led to a new appreciation for hydroxychloroquine as an essential baseline medication. Although much needs to be learned, modulation of the immune system via B-cell depletion is entering clinical practice. Mycophenolate mofetil is an effective and safer alternative to cyclophosphamide for many patients with lupus nephritis. Several other therapeutic approaches are at various stages of preclinical and clinical development. These include anticytokine therapies, co-stimulatory blockade, antigen-specific immune modulation and haematopoietic stem cell transplantation.

Efficacité du rituximab dans les hémophilies acquises: à propos de deux cas et revue de la littérature

INTRODUCTION

Acquired hemophilia due to an inhibitor of factor VIII is a rare clinical situation.

EXEGESIS

Rituximab is now used in the treatment of acquired hemophilia. We report two cases of acquired hemophilia treated by rituximab with efficiency.

CONCLUSION

Rituximab appears to be a first line immunosuppressive therapy in acquired hemophilia, especially in post-partum hemophilia.