Influence of FCGR3A genotype on the therapeutic response to rituximab in rheumatoid arthritis: an observational cohort study

Mechanisms of Resistance to Rituximab Used for the Treatment of Autoimmune Blistering Diseases

Autoimmune blistering diseases represent a group of chronic severe, disabling, and potentially fatal disorders of the skin and/or mucous membranes, primarily mediated by pathogenic auto-antibodies. Despite their rarity, these diseases are associated with significant morbidity and mortality and profound negative impact on the patient's quality of life and impose a considerable economic burden. Rituximab, an anti-CD-20 monoclonal antibody, represents the first line of therapy for pemphigus, regardless of severity and a valuable off-label therapeutic alternative for subepidermal autoimmune blistering diseases as it ensures high rates of rapid, long-lasting complete remission. Nevertheless, disease recurrence is the rule, all patients requiring maintenance therapy with rituximab eventually. While innate resistance to rituximab in pemphigus patients is exceptional, acquired resistance is frequent and may develop even in patients with initial complete response to rituximab, representing a real challenge for physicians. We discuss the various resistance mechanisms and their complex interplay, as well as the numerous therapeutic alternatives that may be used to circumvent rituximab resistance. As no therapeutic measure is universally efficient, individualization of rituximab treatment regimen and tailored adjuvant therapies in refractory autoimmune blistering diseases are mandatory.

The Association between Genetics and Response to Treatment with Biologics in Patients with Psoriasis, Psoriatic Arthritis, Rheumatoid Arthritis, and Inflammatory Bowel Diseases: A Systematic Review and Meta-Analysis

Genetic biomarkers could potentially lower the risk of treatment failure in chronic inflammatory diseases (CID) like psoriasis, psoriatic arthritis (PsA), rheumatoid arthritis (RA), and inflammatory bowel disease (IBD). We performed a systematic review and meta-analysis assessing the association between single nucleotide polymorphisms (SNPs) and response to biologics. Odds ratio (OR) with 95% confidence interval (CI) meta-analyses were performed. In total, 185 studies examining 62,774 individuals were included. For the diseases combined, the minor allele of MYD88 (rs7744) was associated with good response to TNFi (OR: 1.24 [1.02-1.51], 6 studies, 3158 patients with psoriasis or RA) and the minor alleles of NLRP3 (rs4612666) (OR: 0.71 [0.58-0.87], 5 studies, 3819 patients with RA or IBD), TNF-308 (rs1800629) (OR: 0.71 [0.55-0.92], 25 studies, 4341 patients with psoriasis, RA, or IBD), FCGR3A (rs396991) (OR: 0.77 [0.65-0.93], 18 studies, 2562 patients with psoriasis, PsA, RA, or IBD), and TNF-238 (rs361525) (OR: 0.57 [0.34-0.96]), 7 studies, 818 patients with psoriasis, RA, or IBD) were associated with poor response to TNFi together or infliximab alone. Genetic variants in TNFα, NLRP3, MYD88, and FcRγ genes are associated with response to TNFi across several inflammatory diseases. Most other genetic variants associated with response were observed in a few studies, and further validation is needed.

Towards Personalized Medicine in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic, incurable, multisystem, inflammatory disease characterized by synovitis and extra-articular features. Although several advanced therapies targeting inflammatory mechanisms underlying the disease are available, no advanced therapy is universally effective. Therefore, a ceiling of treatment response is currently accepted where no advanced therapy is superior to another. The current challenge for medical research is the discovery and integration of predictive markers of drug response that can be used to personalize medicine so that the patient is started on "the right drug at the right time". This review article summarizes our current understanding of predicting response to anti-rheumatic drugs in RA, obstacles impeding the development of personalized medicine approaches and future research priorities to overcome these barriers.

Inebilizumab reduces neuromyelitis optica spectrum disorder risk independent of FCGR3A polymorphism

Inebilizumab, a humanized, glycoengineered, IgG1 monoclonal antibody that depletes CD19+ B-cells, is approved to treat aquaporin 4 (AQP4) IgG-seropositive neuromyelitis optica spectrum disorder (NMOSD). Inebilizumab is afucosylated and engineered for enhanced affinity to Fc receptor III-A (FCGR3A) receptors on natural killer cells to maximize antibody-dependent cellular cytotoxicity. Previously, the F allele polymorphism at amino acid 158 of the FCGR3A gene (F158) was shown to decrease IgG-binding affinity and reduce rituximab (anti-CD20) efficacy for NMOSD attack prevention. In contrast, our current findings from inebilizumab-treated NMOSD patients indicate similar clinical outcomes between those with F158 and V158 allele genotypes.

Association between functional FCGR3A F158V and FCGR2A R131H polymorphisms and responsiveness to rituximab in patients with autoimmune diseases: a meta-analysis

OBJECTIVES

To investigate the association between the functional Fc gamma receptor 3 A (FCGR3A) V158F and FCGR2A R131H polymorphisms and rituximab therapy in patients with autoimmune diseases.

METHODS

We searched the Medline, Embase, and Cochrane databases for relevant articles. We conducted a meta-analysis of the association between FCGR3A V158F and FCGR2A R131H polymorphisms and responsiveness to rituximab in patients with autoimmune diseases.

RESULTS

Eleven studies, consisting of 661 responders and 267 non-responders for FCGR3A V158F polymorphism and 156 responders and 89 non-responders for FCGR2A R131H polymorphism, were included. The meta-analysis revealed a significant association between the FCGR3A V allele and responsiveness to rituximab (odds ratio [OR] = 1.600, 95% confidence interval [CI] = 1.268-2.018, P < 0.001). Furthermore, associations were found using the dominant and homozygous contrast models. Subgroup analysis showed an association between the FCGR3A V allele and responsiveness to rituximab in European, RA, ITP, small (<50) and large (≥50) groups, and short- (≤6 months) and long-term follow-up periods (≥6 months). These associations were also found in recessive, dominant or homozygous contrast models. Meta-analysis revealed no association between the FCGR2A R allele and responsiveness to rituximab (OR = 1.243, 95% CI = 0.825-1.873, P = 0.229).

CONCLUSIONS

We demonstrated that the FCGR3A F158V polymorphism is associated with better responsiveness to rituximab therapy in patients with autoimmune diseases, indicating that individuals carrying the FCGR3A V allele will likely respond better to rituximab. However, FCGR2A R131H polymorphism was not associated with better response to rituximab.

Association between the functional FCGR3A F158V and FCGR2A R131H polymorphisms and responsiveness to biologics in rheumatoid arthritis patients: A meta-analysis

OBJECTIVES

This study aimed to investigate the association between functional Fc gamma receptor 3A (FCGR3A) V158F and FCGR2A R131H polymorphisms and biologic therapy in rheumatoid arthritis (RA) patients.

METHODS

We searched Medline, Embase, and Cochran databases for available articles. This study is a meta-analysis of the association between the FCGR3A V158F and FCGR2A R131H polymorphisms and their responsiveness to biologics in RA patients.

RESULTS

Seventeen studies involving RA patients with FCGR3A V158F (n = 1884) and FCGR2A R131H (n = 1118) polymorphisms were considered. This meta-analysis showed that the FCGR3A V allele was associated with responsiveness to rituximab (odds ratio [OR] = 1.431, 95% CI = 1.081-1.894, P = 0.012), but not with tumor necrosis factor (TNF) blockers, tocilizumab, or abatacept. A significant association was also found between the FCGR3A V158F polymorphism and responsiveness to biologics using the dominant-recessive model. Additionally, the FCGR3A V158F polymorphism was associated with responsiveness to TNF blockers in the homozygous contrast model. Meta-analysis revealed an association between the FCGR2A RR + RH genotype and responsiveness to biologics (OR = 1.385, 95% CI = 1.007-1.904, P = 0.045).

CONCLUSIONS

This meta-analysis demonstrates that FCGR3A V allele carriers show better responsiveness to rituximab, and FCGR2A R allele carriers may show a better response to biologics in RA treatment. Genotyping of these polymorphisms could be a useful tool to find associations with the responsiveness of personalized medicine to biologics.

Comprehensive genetic and functional analyses of Fc gamma receptors influence on response to rituximab therapy for autoimmunity

BACKGROUND

Rituximab is widely used to treat autoimmunity but clinical response varies. Efficacy is determined by the efficiency of B-cell depletion, which may depend on various Fc gamma receptor (FcγR)-dependent mechanisms. Study of FcγR is challenging due to the complexity of the FCGR genetic locus. We sought to assess the effect of FCGR variants on clinical response, B-cell depletion and NK-cell-mediated killing in rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE).

METHODS

A longitudinal cohort study was conducted in 835 patients [RA = 573; SLE = 262]. Clinical outcome measures were two-component disease activity score in 28-joints (2C-DAS28CRP) for RA and British Isles Lupus Assessment Group (BILAG)-2004 major clinical response (MCR) for SLE at 6 months. B-cells were evaluated by highly-sensitive flow cytometry. Single nucleotide polymorphism and copy number variation for genes encoding five FcγRs were measured using multiplex ligation-dependent probe amplification. Ex vivo studies assessed NK-cell antibody-dependent cellular cytotoxicity (ADCC) and FcγR expression.

FINDINGS

In RA, carriage of FCGR3A-158V and increased FCGR3A-158V copies were associated with greater 2C-DAS28CRP response (adjusted for baseline 2C-DAS28CRP). In SLE, MCR was associated with increased FCGR3A-158V, OR 1.64 (95% CI 1.12-2.41) and FCGR2C-ORF OR 1.93 (95% CI 1.09-3.40) copies. 236/413 (57%) patients with B-cell data achieved complete depletion. Homozygosity for FCGR3A-158V and increased FCGR3A-158V copies were associated with complete depletion in combined analyses. FCGR3A genotype was associated with rituximab-induced ADCC, and increased NK-cell FcγRIIIa expression was associated with improved clinical response and depletion in vivo. Furthermore, disease status and concomitant therapies impacted both NK-cell FcγRIIIa expression and ADCC.

INTERPRETATION

FcγRIIIa is the major low affinity FcγR associated with rituximab response. Increased copies of the FCGR3A-158V allele (higher affinity for IgG1), influences clinical and biological responses to rituximab in autoimmunity. Enhancing FcγR-effector functions could improve the next generation of CD20-depleting therapies and genotyping may stratify patients for optimal treatment protocols.

FUNDING

Medical Research Council, National Institute for Health and Care Research, Versus Arthritis.

Predicting Sustained Clinical Response to Rituximab in Moderate to Severe Systemic Manifestations of Primary Sjögren Syndrome

OBJECTIVE

To assess outcomes of repeat rituximab cycles and identify predictors of sustained clinical response in systemic manifestations of primary Sjögren syndrome (pSS).

METHODS

An observational study was conducted in 40 rituximab-treated patients with pSS. Clinical response was defined as a 3-point or more reduction in the European League Against Rheumatism (EULAR) Sjögren Disease Activity Index (ESSDAI) at 6 months from baseline. Peripheral blood B cells were measured using highly sensitive flow cytometry. Predictors of sustained response (within two rituximab cycles) were analyzed using penalized logistic regression.

RESULTS

Thirty-eight out of 40 patients had moderate to severe systemic disease (ESSDAI >5). Main domains were articular (73%), mucocutaneous (23%), hematological (20%), and nervous system (18%). Twenty-eight out of 40 (70%) patients were on concomitant immunosuppressants. One hundred sixty-nine rituximab cycles were administered with a total follow-up of 165 patient-years. In cycle 1 (C1), 29/40 (73%) achieved ESSDAI response. Of C1 responders, 23/29 received retreatment on clinical relapse, and 15/23 (65%) responded. Of the 8/23 patients who lost response, these were due to secondary non-depletion and non-response (2NDNR; 4/23 [17%] as we previously observed in systemic lupus erythematosus with antirituximab antibodies, inefficacy = 2/23, and other side effects = 2/23). Within two cycles, 13/40 (33%) discontinued therapy. In multivariable analysis, concomitant immunosuppressant (odds ratio 7.16 [95% confidence interval: 1.37-37.35]) and achieving complete B-cell depletion (9.78 [1.32-72.25]) in C1 increased odds of response to rituximab. At 5 years, 57% of patients continued on rituximab.

CONCLUSION

Our data suggest that patients with pSS should be co-prescribed immunosuppressant with rituximab, and treatment should aim to achieve complete depletion. About one in six patients develop 2NDNR in repeat cycles. Humanized or type 2 anti-CD20 antibodies may improve clinical response in extra-glandular pSS.

The weaker-binding Fc γ receptor IIIa F158 allotype retains sensitivity to N-glycan composition and exhibits a destabilized antibody-binding interface

Antibodies engage Fc γ receptors (FcγRs) to elicit healing cellular immune responses following binding to a target antigen. Fc γ receptor IIIa/CD16a triggers natural killer cells to destroy target tissues with cytotoxic proteins and enhances phagocytosis mediated by macrophages. Multiple variables affect CD16a antibody-binding strength and the resulting immune response, including a genetic polymorphism. The predominant CD16a F158 allotype binds antibodies with less affinity than the less common V158 allotype. This polymorphism likewise affects cellular immune responses and clinical efficacy of antibodies relying on CD16a engagement, though it remains unclear how V/F158 affects CD16a structure. Another relevant variable shown to affect affinity is composition of the CD16a asparagine-linked (N)-glycans. It is currently not known how N-glycan composition affects CD16a F158 affinity. Here, we determined N-glycan composition affects the V158 and F158 allotypes similarly, and N-glycan composition does not explain differences in V158 and F158 binding affinity. Our analysis of binding kinetics indicated the N162 glycan slows the binding event, and shortening the N-glycans or removing the N162 glycan increased the speed of binding. F158 displayed a slower binding rate than V158. Surprisingly, we found N-glycan composition had a smaller effect on the dissociation rate. We also identified conformational heterogeneity of CD16a F158 backbone amide and N162 glycan resonances using NMR spectroscopy. Residues exhibiting chemical shift perturbations between V158 and F158 mapped to the antibody-binding interface. These data support a model for CD16a F158 with increased interface conformational heterogeneity, reducing the population of binding-competent forms available and decreasing affinity.

Genome-wide pharmacogenetics of anti-drug antibody response to bococizumab highlights key residues in HLA DRB1 and DQB1

In this largest to-date genetic analysis of anti-drug antibody (ADA) response to a therapeutic monoclonal antibody (MAb), genome-wide association was performed for five measures of ADA status among 8844 individuals randomized to bococizumab, which targets PCSK9 for LDL-C lowering and cardiovascular protection. Index associations prioritized specific amino acid substitutions at the DRB1 and DQB1 MHC class II genes rather than canonical haplotypes. Two clusters of missense variants at DRB1 were associated with general ADA measures (residues 9, 11, 13; and 96, 112, 120, 180) and a third cluster of missense variants in DQB1 was associated with ADA measures including neutralizing antibody (NAb) titers (residues 66, 67, 71, 74, 75). The structural disposition of the missense substitutions implicates peptide antigen binding and CD4 effector function, mechanisms that are potentially generalizable to other therapeutic mAbs.

Clinicaltrials.gov: NCT01968954, NCT01968967, NCT01968980, NCT01975376, NCT01975389, NCT02100514.

Pharmacogenetics of Drug Therapies in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic systemic inflammatory disorder that can lead to severe joint damage and is often associated with a high morbidity and disability. Disease-modifying anti-rheumatic drugs (DMARDs) are the mainstay of treatment in RA. DMARDs not only relieve the clinical signs and symptoms of RA but also inhibit the radiographic progression of disease and reduce the effects of chronic systemic inflammation. Since the introduction of biologic DMARDs in the late 1990s, the therapeutic range of options for the management of RA has significantly expanded. However, patients' response to these agents is not uniform with considerable variability in both efficacy and toxicity. There are no reliable means of predicting an individual patient's response to a given DMARD prior to initiation of therapy. In this chapter, the current published literature on the pharmacogenetics of traditional DMARDS and the newer biologic DMARDs in RA is highlighted. Pharmacogenetics may help individualize drug therapy in patients with RA by providing reliable biomarkers to predict medication toxicity and efficacy.

Toward Overcoming Treatment Failure in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disorder characterized by inflammation and bone erosion. The exact mechanism of RA is still unknown, but various immune cytokines, signaling pathways and effector cells are involved. Disease-modifying antirheumatic drugs (DMARDs) are commonly used in RA treatment and classified into different categories. Nevertheless, RA treatment is based on a "trial-and-error" approach, and a substantial proportion of patients show failed therapy for each DMARD. Over the past decades, great efforts have been made to overcome treatment failure, including identification of biomarkers, exploration of the reasons for loss of efficacy, development of sequential or combinational DMARDs strategies and approval of new DMARDs. Here, we summarize these efforts, which would provide valuable insights for accurate RA clinical medication. While gratifying, researchers realize that these efforts are still far from enough to recommend specific DMARDs for individual patients. Precision medicine is an emerging medical model that proposes a highly individualized and tailored approach for disease management. In this review, we also discuss the potential of precision medicine for overcoming RA treatment failure, with the introduction of various cutting-edge technologies and big data.

Anti-CD20 monoclonal antibodies in Systemic Lupus Erythematosus

Systemic Lupus Erythematosus (SLE) is an autoimmune inflammatory condition with a wide spectrum of disease manifestations and severities, resulting in significant morbidity and mortality. The aetiopathogenesis of SLE is complex. Young women and certain ethnicities are commonly affected, suggesting a significant hormonal and genetic influence. Diverse immunological abnormalities have been described. A characteristic abnormality is the presence of autoantibodies, implicating a central role for B cells in disease pathogenesis and/or perpetuation. Whilst conventional therapies have improved outcomes, a great unmet need remains. Recently, biological therapies are being explored. B-cell depletion therapy with rituximab has been in use off-label for nearly two decades. Inconsistent results between uncontrolled and controlled studies have raised doubts about its efficacy. In this review, we will focus on B cell abnormalities and the rationale behind B-cell depletion therapy with anti-CD20 monoclonal antibody (mAb), rituximab, will be explored including an evaluation of clinical and trial experience. Finally, we will discuss the mechanistic basis for considering alternative anti-CD20 mAbs.

The Pharmacogenetics of Rituximab: Potential Implications for Anti-CD20 Therapies in Multiple Sclerosis

There are a broad range of disease-modifying therapies (DMTs) available in relapsing-remitting multiple sclerosis (RRMS), but limited biomarkers exist to personalise DMT choice. All DMTs, including monoclonal antibodies such as rituximab and ocrelizumab, are effective in preventing relapses and preserving neurological function in MS. However, each agent harbours its own risk of therapeutic failure or adverse events. Pharmacogenetics, the study of the effects of genetic variation on therapeutic response or adverse events, could improve the precision of DMT selection. Pharmacogenetic studies of rituximab in MS patients are lacking, but pharmacogenetic markers in other rituximab-treated autoimmune conditions have been identified. This review will outline the wider implications of pharmacogenetics and the mechanisms of anti-CD20 agents in MS. We explore the non-MS rituximab literature to characterise pharmacogenetic variants that could be of prognostic relevance in those receiving rituximab, ocrelizumab or other monoclonal antibodies for MS.

Polymorphisms Involved in Response to Biological Agents Used in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a systemic disease that leads to joint destruction. During the last decade, the therapy of RA has been principally based on biological drugs. Although the efficacy of biological therapy has been established, patients demonstrated a high heterogeneity in clinical response to treatment. Several genetic polymorphisms play a part in the different response to biological drugs. This review summarizes the pharmacogenetics of biological agents approved for clinical RA treatment. We reviewed PubMed papers published over the past 20 years (2000-2020), inserting as the search term "rheumatoid arthritis and polymorphisms". Despite some studies showing important correlations between genetic polymorphisms and response to biological therapy in RA patients, most of these findings are still lacking and inconsistent. The personalized treatment according to a pharmacogenetics approach is promising but the available pharmacogenetics data on biological treatment in RA are not adequate and reliable to recommend pharmacogenetic tests before starting biological therapy in RA patients.

The evolution in our understanding of the genetics of rheumatoid arthritis and the impact on novel drug discovery

Introduction: Rheumatoid arthritis (RA) is an autoimmune disease that is characterized by chronic inflammation of the joints and affects 1% of the population. Polymorphisms of genes that encode proteins that primarily participate in inflammation may influence RA occurrence or become useful biomarkers for certain types of anti-rheumatic treatment.Areas covered: The authors summarize the recent progress in our understanding of the genetics of RA. In the last few years, multiple variants of genes that are associated with RA risk have been identified. The development of new technologies and the detection of new potential therapeutic targets that contribute to novel drug discovery are also described.Expert opinion: There is still the need to search for new genes which may be a potential target for RA therapy. The challenge is to develop appropriate strategies for achieving insight into the molecular pathways involved in RA pathogenesis. Understanding the genetics, immunogenetics, epigenetics and immunology of RA could help to identify new targets for RA therapy. The development of new technologies has enabled the detection of a number of new genes, particularly genes associated with proinflammatory cytokines and chemokines, B- and T-cell activation pathways, signal transducers and transcriptional activators, which might be potential therapeutic targets in RA.

Effect of Fcγ-receptor 3a (FCGR3A) gene polymorphisms on rituximab therapy in Hungarian patients with rheumatoid arthritis

Background

Rheumatoid arthritis (RA) treatment includes the use of the anti-CD20 monoclonal antibody rituximab (RTX). RTX acts through Fcγ-receptors (FCGR) on effector natural killer cells and macrophages and it can be administered effectively in RA and in lymphomas. Based on the results of in vitro experiments, its efficacy may depend of FCGR gene polymorphisms in both diseases.

Aim

As genetic background of diseases and therapeutic efficacy (pharmacogenetics) may vary among different geographical regions, we wished to assess possible relationships between FCGR3A polymorphism and the therapeutic outcome of RTX therapy in a Hungarian RA cohort.

Patients and methods

Altogether, 52 patients, 6 men and 46 women, were included in the study. Peripheral blood samples were used to determine FCGR3A polymorphism by genotyping using real-time PCR method.

Results

The distribution of FCGR3A genotypes was 8 VV, 34 VF and 10 FF. Disease activity score 28 (DAS28) reductions in patients with VV, VF and FF genotypes were 1.98±0.54 (p=0.008 between DAS28 before and after treatment), 2.07±0.23 (p<0.001) and 1.59±0.52 (p=0.014), respectively. Significant differences in DAS28 reductions on treatment were found between VF heterozygotes and FF homozygotes (p=0.032), as well as between heterozygotes and all (VV+FF) homozygotes (p=0.017). Furthermore, significantly more VV (62.5%; p=0.030) and VF (64.7%; p=0.015) patients achieved low disease activity compared with FF subjects (30.0%).

Conclusion

Our results suggest that FCGR3A polymorphism may predict more effective disease activity reduction by RTX. Furthermore, carrying the V allele may also be associated with better therapeutic response in Hungarian patients with RA.

Prediction of Response to Targeted Treatment in Rheumatoid Arthritis

Rheumatoid arthritis is an autoimmune syndrome presenting with chronic inflammation of the joints. Patients with the same diagnosis can present with different phenotypes. In some patients severe joint inflammation and early joint destruction are observed, whereas a milder phenotype can be seen in others. Conversely, patients with the same signs and symptoms may exhibit different immunological and molecular abnormalities. Since the introduction of early treatment in clinical practice, the treat to target principle, and new medicines such as biologic disease-modifying antirheumatic drugs, clinical remission can be achieved early in the disease course, albeit not in all patients. The clinical response and efficacy of biologic disease-modifying antirheumatic drugs vary among different individuals. Therefore, there is a need to develop a more personalized approach toward treatment to achieve rapid remission in every patient to prevent disability and restore and maintain quality of life, without unnecessary adverse effects, in a cost-effective manner. The latest data from explorative studies of predictive markers of response are discussed here, together with a preliminary treatment algorithm based on currently available knowledge.

Rituximab in Minimal Change Disease: Mechanisms of Action and Hypotheses for Future Studies

Treatment with rituximab, a monoclonal antibody against the B-lymphocyte surface protein CD20, leads to the depletion of B cells. Recently, rituximab was reported to effectively prevent relapses of glucocorticoid-dependent or frequently relapsing minimal change disease (MCD). MCD is thought to be T-cell mediated; how rituximab controls MCD is not understood. In this review, we summarize key clinical studies demonstrating the efficacy of rituximab in idiopathic nephrotic syndrome, mainly MCD. We then discuss immunological features of this disease and potential mechanisms of action of rituximab in its treatment based on what is known about the therapeutic action of rituximab in other immune-mediated disorders. We believe that studies aimed at understanding the mechanisms of action of rituximab in MCD will provide a novel approach to resolve the elusive immune pathophysiology of MCD.

Effect of FCGR polymorphism on the occurrence of late-onset neutropenia and flare-free survival in rheumatic patients treated with rituximab

Background

The causes and mechanisms of late-onset neutropenia (LON) following rituximab treatment in patients with rheumatic diseases are not known. In this study, we aimed to investigate the role of established Fcγ receptor gene (FCGR) polymorphisms and B-cell-activating factor (BAFF) gene promoter polymorphisms for the development of LON and for the efficacy of rituximab in patients with rheumatic diseases.

Methods

A single-center case-control retrospective study was nested in a cohort of 214 consecutive patients with rheumatic diseases treated with rituximab. Eleven patients presented with LON. Fifty non-LON control subjects were matched by diagnosis, age, sex, and treatments. Single-nucleotide polymorphisms of FCGR (FCGR2A 131H/R, FCGR2B 232I/T, FCGR3A 158V/F) and BAFF promoter polymorphism −871C/T were analyzed with polymerase chain reaction-based techniques, and serum immunoglobulin M (IgM) and BAFF levels were analyzed by enzyme-linked immunosorbent assay. Flare-free survival was related to LON occurrence and polymorphisms.

Results

The FCGR3A V allele, but not other FCGR polymorphisms, correlated with the occurrence of LON; each V allele conferred a fourfold increased OR for LON (p = 0.017). FCGR3A 158V/V and presentation with LON were associated with a longer flare-free survival (p = 0.023 and p = 0.031, respectively). FCGR3A 158V/V was related to lower IgM levels (p = 0.016). Serum BAFF levels showed no relationship with LON and BAFF −871C/T promoter polymorphism. There was a tendency toward longer flare-free survival in patients with the BAFF −871T/T allotype compared with the C/T or C/C allotypes (p = 0.096).

Conclusions

The results of the present study suggest that presentation with LON may be a result of the intrinsic efficacy of rituximab in patients with rheumatic diseases. LON could indicate a longer biological and therapeutic activity of rituximab modulated by a certain genotypic polymorphism: the high-affinity FCGR3A V allele. This genotype and the occurrence of LON are both related to longer flare-free survival, suggestive of common mechanisms for LON and duration of response to rituximab. The role of the BAFF −871C/T promoter polymorphism in LON occurrence is unclear.

Single nucleotide polymorphisms in the FcγR3A and TAP1 genes impact ADCC in cynomolgus monkey PBMCs

Phenotypic variability is often observed in cynomolgus monkeys on preclinical studies and may, in part, be driven by genetic variability. However, the role of monkey genetic variation remains largely unexplored in the context of drug response. This study evaluated genetic variation in cynomolgus monkey FcγR3A and TAP1 genes and the potential impact of identified polymorphisms on antibody-dependent cell-mediated cytotoxicity (ADCC) in vitro. Studies in humans have demonstrated that a single nucleotide polymorphism (SNP), F158V, in FcγR3A can influence response to rituximab through altered ADCC and that SNPs in TAP1/2 decrease natural killer (NK) cell activity against major histocompatibility complex (MHC) class I deficient cells, potentially through altered ADCC. Monkeys were genotyped for FcγR3A and TAP1 SNPs, and ADCC was assessed in vitro using peripheral blood mononuclear cells (PBMCs) treated with trastuzumab in the presence of NCI-N87 cells. FcγR3A g.1134A>C (exonic S42R), FcγR3A g.5027A>G (intronic), and TAP1 g.1A>G (start codon loss) SNPs were all significantly associated with decreased ADCC for at least one trastuzumab concentration ≥0.0001 μM when compared with wild type (WT). Regression analysis demonstrated significant association of the SNP-SNP pairs FcγR3A g.1134A>C/TAP1 g.1A>G and FcγR3A g.5027A>G/TAP1 g.1A>G with a combinatorial decrease on ADCC. Mechanisms underlying the decreased ADCC were investigated by measuring FcγR3A/IgG binding affinity and expression of FcγR3A and TAP1 in PBMCs; however, no functional associations were observed. These data demonstrate that genetic variation in cynomolgus monkeys is reflective of known human genetic variation and may potentially contribute to variable drug response in preclinical studies.

Improving B-cell depletion in systemic lupus erythematosus and rheumatoid arthritis

INTRODUCTION

Rituximab-based B-cell depletion (BCD) therapy is effective in refractory rheumatoid arthritis (RA) and although used to treat patients with refractory systemic lupus erythematosus (SLE) in routine clinical practice, rituximab failed to meet the primary endpoints in two large randomised controlled trials (RCTs) of non-renal (EXPLORER) and renal (LUNAR) SLE. Areas covered: We review how BCD could be improved to achieve better clinical responses in RA and SLE. Insights into the variability in clinical response to BCD in RA and SLE may help develop new therapeutic strategies. To this end, a literature search was performed using the following terms: rheumatoid arthritis, systemic erythematosus lupus, rituximab and B-cell depletion. Expert commentary: Poor trial design may have, at least partly, contributed to the apparent lack of response to BCD in the two RCTs of patients with SLE. Enhanced B-cell depletion and/or sequential therapy with belimumab may improve clinical response at least in some patients with SLE.

Optimising B-cell depletion in autoimmune disease: is obinutuzumab the answer?

In Rheumatoid Arthritis (RA) and Systemic Lupus Erythematosus (SLE), B-cell depletion therapy using rituximab results in variable clinical responses between individuals, which likely relates to variable B-cell depletion in the presence of immune defects. Outcomes in clinical trials with other type I anti-CD20 mAbs, ocrelizumab and ofatumumab, are comparable to rituximab. A mechanistically different type II mAb, obinutuzumab (OBZ), with greater capacity for B-cell depletion, has recently entered clinical trials in SLE. Here we consider whether type II anti-CD20 mAbs will provide mechanistic advantages to overcome the disease-related immune defects in autoimmune diseases such as SLE.

Genetic data: The new challenge of personalized medicine, insights for rheumatoid arthritis patients

Rapid advances in genotyping technology, analytical methods, and the establishment of large cohorts for population genetic studies have resulted in a large new body of information about the genetic basis of human rheumatoid arthritis (RA). Improved understanding of the root pathogenesis of the disease holds the promise of improved diagnostic and prognostic tools based upon this information. In this review, we summarize the nature of new genetic findings in human RA, including susceptibility loci and gene-gene and gene-environment interactions, as well as genetic loci associated with sub-groups of patients and those associated with response to therapy. Possible uses of these data are discussed, such as prediction of disease risk as well as personalized therapy and prediction of therapeutic response and risk of adverse events. While these applications are largely not refined to the point of clinical utility in RA, it seems likely that multi-parameter datasets including genetic, clinical, and biomarker data will be employed in the future care of RA patients.

FCGR polymorphisms in the treatment of rheumatoid arthritis with Fc-containing TNF inhibitors

OBJECTIVES

Reproducible association of a functional polymorphism in FCGR2A with response to a TNF inhibitor (TNFi) in patients with rheumatoid arthritis (RA) led us to explore other FcγR functional polymorphisms.

METHODS

Functional polymorphisms FCGR3A F158V, FCGR2B I223T and promoter VNTR in FCGRT were analyzed in up to 429 patients with RA. Response to TNFi was recorded during standard care at 3, 6 and 12 months of follow-up. Fixed effects meta-analysis of studies addressing FCGR3A F158V polymorphism, which is the most studied of these polymorphisms, was conducted with inverse variance weighting.

RESULTS

None of the functional polymorphisms were associated with change in DAS28. Meta-analysis of the seven studies (899 patients) with available data addressing association of FCGR3A F158V with response to TNFi in RA showed no association (OR: 1.11, 95% CI: 0.8-1.5; p = 0.5).

CONCLUSION

None of the three functional polymorphisms in FcγR genes showed association with response to TNFi in patients with RA. These negative results were obtained in spite of the larger size of this study relative to previous studies addressing the same polymorphisms. In addition, meta-analysis of FCGR3A F158V was also negative against the results provided by previous studies. Original submitted 17 September 2014; Revision submitted 9 December 2014.

Personalized biological treatment for rheumatoid arthritis: a systematic review with a focus on clinical applicability

OBJECTIVES

To review studies that address prediction of response to biologic treatment in RA and to explore the clinical utility of the studied (bio)markers.

METHODS

A search for relevant articles was performed in PubMed, Embase and Cochrane databases. Studies that presented predictive values or in which these could be calculated were selected. The added value was determined by the added value on prior probability for each (bio)marker. Only an increase/decrease in chance of response ⩾15% was considered clinically relevant, whereas in oncology values >25% are common.

RESULTS

Of the 57 eligible studies, 14 (bio)markers were studied in more than one cohort and an overview of the added predictive value of each marker is presented. Of the replicated predictors, none consistently showed an increase/decrease in probability of response ⩾15%. However, positivity of RF and ACPA in case of rituximab and the presence of the TNF-α promoter 308 GG genotype for TNF inhibitor therapy were consistently predictive, yet low in added predictive value. Besides these, 65 (bio)markers studied once showed remarkably high (but not validated) predictive values.

CONCLUSION

We were unable to address clinically useful baseline (bio)markers for use in individually tailored treatment. Some predictors are consistently predictive, yet low in added predictive value, while several others are promising but await replication. The challenge now is to design studies to validate all explored and promising findings individually and in combination to make these (bio)markers relevant to clinical practice.

The effect of gene polymorphisms on patient responses to rheumatoid arthritis therapy

INTRODUCTION

Rheumatoid arthritis (RA) is a systemic disease leading to joint destruction. The therapy of RA is mainly based on disease-modifying anti-rheumatic drugs (DMARDs) and biological drugs. The response to treatment is different among patients. Therefore, we have searched for factors that may predict the efficacy and toxicity during therapy in individual patients.

AREAS COVERED

This review presents the role of genetic polymorphisms as predictors of the efficacy and toxicity during the therapy of RA patients with DMARDs (methotrexate, leflunomide, sulfasalazine) and biological drugs (anti-TNF-alpha antagonists, Tocilizumab, Rituximab).

EXPERT OPINION

Despite studies having shown an association between genetic polymorphisms and response to therapy in RA patients, the majority of these findings are still inconclusive and inconsistent. We are still far from applying pharmacogenetic tests in routine clinical practice that can predict the outcome of treatment. Several factors, such as small sample size with low statistical power, variability in the outcome definitions and the heterogeneity of the cohorts, limited number of tested single nucleotide polymorphisms (SNPs), small effect for the selected variant, and a lack of consideration of epigenetic factors, may contribute to the inconsistency observed and may lead to limited success in personalizing therapy.

Spanish Rheumatology Society and Hospital Pharmacy Society Consensus on recommendations for biologics optimization in patients with rheumatoid arthritis, ankylosing spondylitis and psoriatic arthritis

OBJECTIVE

The aim of this study was to establish guidelines for the optimization of biologic therapies for health professionals involved in the management of patients with RA, AS and PsA.

METHODS

Recommendations were established via consensus by a panel of experts in rheumatology and hospital pharmacy, based on analysis of available scientific evidence obtained from four systematic reviews and on the clinical experience of panellists. The Delphi method was used to evaluate these recommendations, both between panellists and among a wider group of rheumatologists.

RESULTS

Previous concepts concerning better management of RA, AS and PsA were reviewed and, more specifically, guidelines for the optimization of biologic therapies used to treat these diseases were formulated. Recommendations were made with the aim of establishing a plan for when and how to taper biologic treatment in patients with these diseases.

CONCLUSION

The recommendations established herein aim not only to provide advice on how to improve the risk:benefit ratio and efficiency of such treatments, but also to reduce variability in daily clinical practice in the use of biologic therapies for rheumatic diseases.

Population Pharmacokinetics of Obinutuzumab (GA101) in Chronic Lymphocytic Leukemia (CLL) and Non-Hodgkin's Lymphoma and Exposure-Response in CLL

Treatment regimens involving obinutuzumab (GA101) demonstrated increased efficacy to rituximab in clinical trials for non-Hodgkin's lymphoma (NHL) and chronic lymphocytic leukemia (CLL). However, the pharmacokinetic (PK) properties and the exposure–response relationships of obinutuzumab still need to be fully described. Data from four clinical trials of obinutuzumab were analyzed to describe the PK properties in patients with NHL or CLL and the pharmacodynamic (PD) properties in patients with CLL. A population PK model with linear time-dependent clearance described the obinutuzumab concentration–time course. Diagnosis, baseline tumor size (BSIZ), body weight, and gender were the main covariates affecting obinutuzumab exposure. In patients with CLL, exposure was not associated with safety but showed positive trends of correlation with efficacy. Although efficacy correlated positively with exposure, since both efficacy and exposure correlated negatively with BSIZ, it was not possible to determine with certainty whether it would be beneficial to adjust the dose according to BSIZ.

Functional FCGR3A 158 V/F and IL-6 -174 C/G polymorphisms predict response to biologic therapy in patients with rheumatoid arthritis: a meta-analysis

The aim of this study was to investigate whether the Fc gamma receptor 3A (FCGR3A) 158 V/F and interleukin-6 (IL-6) promoter -174 G/C polymorphisms can predict the response to biologic-based therapy in patients with rheumatoid arthritis (RA). We conducted a meta-analysis of studies on the association between the FCGR3A V/F polymorphism or the IL-6 -174 C/G polymorphism and non-responsiveness to biologic therapy in RA patients. A total of 10 studies involving 1,427 patients were considered. These studies consisted of seven studies on the FCGR3A polymorphism and three studies on the IL-6 polymorphism. Meta-analysis showed no association between the FCGR3A VV+VF genotype and non-responders to biologic therapy [odds ratio (OR) 0.881, 95 % confidence interval (CI) 0.505-1.537, p = 0.655]. However, stratification by biologic type indicated an association between the FCGR3A VV+VF genotype and non-responders to rituximab (OR 0.566, 95 % CI 0.373-0.857, p = 0.007), but no association was found in non-responders to tumor necrosis factor (TNF)-blockers (OR 1.337, 95 % CI 0.869-2.056, p = 0.186). Meta-analysis revealed no association between the IL-6 CC+CG genotype and non-responders to the biologics (OR 3.233, 95 % CI 0.766-13.64, p = 0.110). However, an association was found between the IL-6 CC+CG genotype and non-responders to anti-TNF therapy (OR 8.030, 95 % CI 1.807-33.68, p = 0.006). This meta-analysis demonstrates that FCGR3A V allele carriers show a better response to rituximab, and individuals carrying the IL-6 -174 C allele show a poorer response to anti-TNF therapy for RA. Genotyping for these polymorphisms may be a useful tool for predicting the response to biologics with respect to personalized medicine.

Pharmacogenetics in rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic inflammatory arthritis leading to severe joint damage and associated with high morbidity and mortality. Disease-modifying antirheumatic drugs (DMARDs) are the mainstay of treatment in RA. DMARDs not only relieve the clinical signs and symptoms of RA but also inhibit the radiographic progression of disease. In the last decade, a new class of disease-modifying medications, the biologic agents, has been added to the existing spectrum of DMARDs in RA. However, patients' response to these agents is not uniform with considerable variability in both efficacy and toxicity. There are no reliable means of predicting an individual patient's response to a given DMARD prior to initiation of therapy. In this chapter, the current published literature on the pharmacogenetics of traditional DMARDS and the newer biologic DMARDs in RA is highlighted. Pharmacogenetics may help individualize drug therapy in patients with RA in the near future.

Detection of the FCGR3a polymorphism using a real-time polymerase chain reaction assay

The fragment crystallizable (Fc) region of the immunoglobulin G, low affinity III A receptor (FCGR3a, also known as CD16) belongs to the Fc gamma receptor family (FCGR), which plays an important role in immunoinflammatory processes. It is a low affinity, transmembrane receptor that is mainly expressed in monocytes, natural killer cells, and macrophages. It has been implicated in various inflammatory conditions, and recently a polymorphism (rs396991) in this gene has been shown to influence response to rituximab (anti-CD20) therapy in various disorders. We evaluated two molecular methods to genotype this polymorphism. Archived, formalin-fixed, paraffin-embedded samples from 26 biopsies of diffuse large B-cell lymphoma were retrieved and DNA was extracted. The samples were tested for the FCGR3a polymorphism using real-time polymerase chain reaction (PCR) followed by melt curve analysis or by a standard TaqMan allelic discrimination assay using the ABI 7500 FAST real-time PCR instrument. With the TaqMan allelic discrimination assay, we found that 16 cases were the wild type genotype, homozygous phenylalanine (F/F), for the FCGR3a receptor, whereas two cases had the homozygous valine (V/V) polymorphism and eight cases were heterozygous with a V/F genotype. Results with the real-time PCR followed by melt curve analysis were similar for 25 cases; however, four samples did not have sufficient DNA for the melt curve analysis method, and the result from one sample was discordant. The new TaqMan assay offers several advantages over previously published assays, such as faster turnaround time and ease of interpretation. These performance characteristics make it highly suitable for use in a clinical laboratory.

Pharmacogenetics of disease-modifying antirheumatic drugs in rheumatoid arthritis: towards personalized medicine

Rheumatoid arthritis is a disease showing considerable heterogeneity in all its aspects, including response to therapy. The efficacy of disease-modifying antirheumatic drugs (DMARDs), with or without biological activity, has been unambiguously established. DMARDs improve the symptoms associated with the disease, and, even more importantly, are capable of stagnating the joint damage associated with the disease. Nonetheless, a considerable proportion of patients fail to achieve an adequate response and/or experience toxicity. This variability in treatment response between individuals has given rise to an extensive search for prognostic markers in order to personalize and optimize therapy in rheumatoid arthritis patients. Pharmacogenetics, the study of genetic variation underlying differential responses to drugs, is a rapidly progressing field in rheumatology that might enable personalized therapy in rheumatic diseases. This review will summarize the pharmacogenetics of commonly used synthetic and biological DMARDs.