B cell activation biomarkers as predictive factors for the response to rituximab in rheumatoid arthritis: A six‐month,national, multicenter,open‐label study

Objective

To examine whether serum B cell markers can predict response to rituximab, a B cell–depleting monoclonal antibody, in patients with refractory rheumatoid arthritis (RA).

Methods

This rituximab re‐treatment dose study (SMART [eSsai MAbthera sur la dose de Re‐Traitement]) involved 208 patients with refractory RA. Serum markers of B cell activation (anti–cyclic citrullinated peptide [anti‐CCP] antibodies, rheumatoid factor [RF], serum IgG, IgA, and IgM levels, serum κ and λ free light chains, and serum BAFF) were assessed before the first rituximab cycle (1,000 mg on days 1 and 15). Univariate and multivariate analyses were performed to identify factors associated with a European League Against Rheumatism (EULAR) response at 24 weeks.

Results

There were 149 responders (72%). Two baseline factors were associated with a EULAR response at 24 weeks in multivariate analysis: the presence of anti‐CCP antibodies or RF (odds ratio 3.5 [95% confidence interval 1.6–7.6]) and a serum IgG concentration above normal (odds ratio 2.11 [95% confidence interval 1.02–4.33]), with synergy between them (odds ratio 6.0 [95% confidence interval 2.2–16.2]).

Conclusion

The presence of RF or anti‐CCP antibodies and elevated IgG are 2 simple biomarkers that can be used routinely before therapy to predict response to rituximab in patients with refractory RA.

     

Regeneration of B cell subsets after transient B cell depletion using anti‐CD20 antibodies in rheumatoid arthritis

Objective

Transient B cell depletion with the monoclonal anti‐CD20 antibody rituximab has resulted in favorable clinical responses in patients with rheumatoid arthritis (RA). However, little is known about the regeneration profile of different peripheral B cell subpopulations. The aim of this study was to delineate the regeneration profile of different B cell subsets in the peripheral blood after selective anti‐CD20–mediated B cell depletion.

Methods

Seventeen patients with RA refractory to standard therapy were treated with rituximab. Patients 1–6 received 4 weekly infusions of rituximab at a dose of 375 mg/m², and patients 7–17 received 2 infusions of rituximab (1,000 mg), 2 weeks apart. Four‐color staining was performed at several time points, using CD38, IgD, and CD27 in addition to other cell surface markers. In one patient, the mutational status of the immunoglobulin receptor was examined.

Results

The analysis revealed a distinct pattern of B cell regeneration. The first wave of repopulating B cells were immature B cells (CD38^high,IgD+,CD10+,CD24^high), the immunoglobulin receptors of which were not yet somatically mutated. In parallel, a recirculation of plasma cells was observed. Later, the number of naive B cells increased, and these cells predominated in the peripheral blood B cell pool. CD27+ memory B cells showed a slow and delayed repopulation, and the level of these cells stayed significantly reduced (<50%) compared with baseline values, for more than 2 years.

Conclusion

Our findings provide evidence for a characteristic regeneration pattern of B cell subpopulations, with long‐lasting modulation of B cell subset composition, after selective anti‐CD20–mediated B cell depletion.

     

B cell depletion with rituximab in patients with diffuse cutaneous systemic sclerosis

Objective

To determine the safety of rituximab, to provide preliminary data regarding the potential efficacy of rituximab, and to investigate the effects of rituximab on autoimmunity and fibrosis in patients with diffuse cutaneous systemic sclerosis (dcSSc).

Methods

Fifteen patients with dcSSc, all of whom experienced their first non–Raynaud's disease–associated disease manifestation within 18 months of trial entry, were recruited to receive 2 intravenous doses of rituximab (1,000 mg), administered 2 weeks apart. Safety, clinical, and exploratory outcomes were evaluated at baseline and at 6 months. The primary outcome was the change in the modified Rodnan skin thickness score (MRSS) at 6 months compared with baseline.

Results

Adverse events included frequent infusion reactions and rare infections (urinary tract infection and dental abscess occurred in 1 patient each). The mean change in the MRSS between baseline and 6 months was not significant. Results of pulmonary function tests and other measures of major organ involvement were stable. The modest B cell infiltrates that were present in most skin biopsy specimens at baseline were completely depleted at 6 months in most patients. Autoantibody titers showed only modest and variable changes after treatment.

Conclusion

In this pilot study, treatment with rituximab appeared to be safe and well tolerated among patients with dcSSc. Rituximab treatment resulted in both depletion of circulating B cells and depletion of dermal B cells but had little effect on the levels of SSc‐associated autoantibodies. Rituximab treatment did not appear to result in a significant beneficial effect on skin disease. The potential efficacy of rituximab in other organs such as the lung could not be clearly evaluated in this small open‐label trial.

     

B cell depletion as a novel treatment for systemic lupus erythematosus: A phase I/II dose‐escalation trial of rituximab

Objective

Safer and more effective therapies are needed for the treatment of systemic lupus erythematosus (SLE). B lymphocytes have been shown to play fundamental pathogenic roles in SLE, and therefore, elimination of B cells with the use of rituximab may represent a new therapy for SLE.

Methods

A phase I/II dose‐escalation trial of rituximab added to ongoing therapy in SLE was conducted. Rituximab was administered as a single infusion of 100 mg/m² (low dose), a single infusion of 375 mg/m² (intermediate dose), or as 4 infusions (1 week apart) of 375 mg/m² (high dose). CD19+ lymphocytes were measured to determine the effectiveness of B cell depletion. The Systemic Lupus Activity Measure (SLAM) score was used as the primary outcome for clinical efficacy.

Results

Rituximab was well tolerated in this patient population, with most experiencing no significant adverse effects. Only 3 serious adverse events, which were thought to be unrelated to rituximab administration, were noted. A majority of patients (11 of 17) had profound B cell depletion (to <5 CD19+ B cells/μl). In these patients, the SLAM score was significantly improved at 2 and 3 months compared with baseline (P = 0.0016 and P = 0.0022, respectively, by paired t‐test). This improvement persisted for 12 months, despite the absence of a significant change in anti–double‐stranded DNA antibody and complement levels. Six patients developed human antichimeric antibodies (HACAs) at a level ≥100 ng/ml. These HACA titers were associated with African American ancestry, higher baseline SLAM scores, reduced B cell depletion, and lower levels of rituximab at 2 months after initial infusion.

Conclusion

Rituximab therapy appears to be safe for the treatment of SLE and holds significant therapeutic promise, at least for the majority of patients experiencing profound B cell depletion. Based on these results, controlled trials of rituximab appear to be warranted.

     

The relationship of FcγRIIIa genotype to degree of B cell depletion by rituximab in the treatment of systemic lupus erythematosus

Objective

Despite wide use of the anti‐CD20 monoclonal antibody rituximab in the treatment of B cell lymphomas, the mechanism by which it causes B cell depletion remains a subject of controversy. As part of an ongoing phase I/II trial of rituximab in the treatment of systemic lupus erythematosus (SLE), we sought to determine whether the effectiveness of B cell depletion was influenced by polymorphisms of Fc receptors (FcR) on effector cells.

Methods

During rituximab treatment of 12 SLE patients, B cell depletion was monitored as a function of the serum rituximab level and FcγRIIa and FcγRIIIa genotypes at baseline and at 1 month and 2 months after treatment. FcR genotypes were determined by polymerase chain reaction. Serum levels of rituximab were measured by enzyme‐linked immunosorbent assay (ELISA). B lymphocyte percentages were assessed by flow cytometry.

Results

B cell depletion was highly variable in this patient cohort, with B cell percentages at the 1–2‐month posttreatment nadir ranging from undetectable (<0.1 cell/μl) to 16% (∼30 cells/μl) of the total peripheral blood lymphocytes. At 2 months posttreatment, B cell percentages were highly correlated with both the serum rituximab level and the FcγRIIIa genotype (R² = 0.75, P = 0.002). The FcγRIIIa genotype was a significant independent predictor of the efficacy of B cell depletion (P = 0.019).

Conclusion

These results highlight the potential variability of B cell depletion by rituximab in the treatment of autoimmune disease and indicate that Fc receptors are an important determinant of that variability. The findings further suggest the importance of antibody‐dependent cell‐mediated cytotoxicity and/or apoptosis induction via FcγRIIIa‐expressing effector cells in the mechanism of B cell depletion by this widely used monoclonal antibody.

     

Efficacy and safety of rituximab in moderately‐to‐severely active systemic lupus erythematosus: The randomized,double‐blind,phase ii/iii systemic lupus erythematosus evaluation of rituximab trial

Objective

B cells are likely to contribute to the pathogenesis of systemic lupus erythematosus (SLE), and rituximab induces depletion of B cells. The Exploratory Phase II/III SLE Evaluation of Rituximab (EXPLORER) trial tested the efficacy and safety of rituximab versus placebo in patients with moderately‐to‐severely active extrarenal SLE.

Methods

Patients entered with ≥1 British Isles Lupus Assessment Group (BILAG) A score or ≥2 BILAG B scores despite background immunosuppressant therapy, which was continued during the trial. Prednisone was added and subsequently tapered. Patients were randomized at a ratio of 2:1 to receive rituximab (1,000 mg) or placebo on days 1, 15, 168, and 182.

Results

In the intent‐to‐treat analysis of 257 patients, background treatment was evenly distributed among azathioprine, mycophenolate mofetil, and methotrexate. Fifty‐three percent of the patients had ≥1 BILAG A score at entry, and 57% of the patients were categorized as being steroid dependent. No differences were observed between placebo and rituximab in the primary and secondary efficacy end points, including the BILAG‐defined response, in terms of both area under the curve and landmark analyses. A beneficial effect of rituximab on the primary end point was observed in the African American and Hispanic subgroups. Safety and tolerability were similar in patients receiving placebo and those receiving rituximab.

Conclusion

The EXPLORER trial enrolled patients with moderately‐to‐severely active SLE and used aggressive background treatment and sensitive cutoffs for nonresponse. No differences were noted between placebo and rituximab in the primary and secondary end points. Further evaluation of patient subsets, biomarkers, and exploratory outcome models may improve the design of future SLE clinical trials.

     

A multicenter survey of rituximab therapy for refractory antineutrophil cytoplasmic antibody–associated vasculitis

Objective

B cell depletion with rituximab has allowed remissions in relapsing or refractory antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis in small studies. The aim of this study was to determine the efficacy and safety of rituximab for ANCA‐associated vasculitis in a larger multicenter cohort. This permitted comparison of rituximab dosing regimens, the value of continuing immunosuppression, and investigation of ANCA and B cell levels as re‐treatment biomarkers.

Methods

Retrospective, standardized data collection from 65 sequential patients receiving rituximab for refractory ANCA‐associated vasculitis at 4 centers in the UK was used.

Results

All patients achieved B cell depletion. Complete remission occurred in 49 of the 65 patients (75%), partial remission in 15 (23%), and no response in 1 (2%). The prednisolone dosage was reduced from 12.5 mg/day (median) to 9.0 mg/day at 6 months (P = 0.0006). Immunosuppressive therapy was withdrawn in 37 of 60 patients (62%). Twenty‐eight of 49 patients who achieved full remission (57%) experienced relapse (median 11.5 months). B cell return preceded relapse in 14 of 27 patients (52%). Although ANCA levels fell after rituximab therapy, relapse was not associated with ANCA positivity or a rise in ANCA levels. Neither the initial rituximab regimen (4 infusions of 375 mg/m² each given 1 week apart or 2 infusions of 1 gm each given 2 weeks apart) nor withdrawal of immunosuppressive therapy (37 of 60 patients [62%]) influenced the timing of relapse. Thirty‐eight patients received ≥2 courses of rituximab, and complete remission was induced or maintained in 32 of them (84%). IgM levels fell, although IgG levels remained stable. Forty‐six serious adverse events occurred, including 2 episodes of late‐onset neutropenia, which were attributed to rituximab.

Conclusion

Rituximab was effective remission induction therapy for refractory ANCA‐associated vasculitis in this study. There was no difference in efficacy between the 2 main treatment regimens. Continuing immunosuppression did not reduce relapses. Relapses occurred, but re‐treatment was effective and safe. There was no clear influence of rituximab on the frequency of serious adverse events. ANCA and B cell levels lacked sufficient sensitivity to guide the timing of re‐treatment.

     

Long‐term comparison of rituximab treatment for refractory systemic lupus erythematosus and vasculitis: Remission,relapse, and re‐treatment

Objective

Current treatments for systemic lupus erythematosus (SLE) and vasculitis contribute to mortality and incapacity and are only partially effective; thus, newer therapies are clearly needed. Depletion of B cells has led to disease control in patients with autoimmune disorders. We sought to assess the long‐term efficacy and safety of a B cell–depleting therapy in patients with SLE and patients with vasculitis.

Methods

In a prospective study with a median followup of 24 months, 11 patients with active or refractory SLE and 11 patients with active or refractory antineutrophil cytoplasmic antibody–associated vasculitis (AAV) received a course of therapy with rituximab (an anti‐CD20 monoclonal antibody) along with a single dose of intravenous cyclophosphamide.

Results

Remission followed rapid B cell depletion, with response rates of 100% among the 11 patients with SLE (6 patients had a complete response, and 5 patients had a partial response) and 91% among the 11 patients with AAV (9 patients had a complete response, and 1 patient had partial remission). A renal response occurred in all 6 patients with lupus nephritis. Clinical improvement was accompanied by significant reductions in the daily dose of prednisolone. Relapse occurred in 64% of the patients with SLE and in 60% of those with AAV. B cell return preceded relapse in the majority of patients, and further treatment with rituximab proved effective. IgG and IgM levels were maintained in the normal range. The incidence of infective complications was low; however, infusion reactions were common, and human antichimeric antibodies developed in 5 of 14 patients.

Conclusion

B cell depletion offers the prospect of sustained disease remission and improved disease control combined with low toxicity in patients with active or refractory SLE or AAV. Relapse following treatment is common, but re‐treatment is rapidly effective.

     

Effect of rituximab on physical function and quality of life in patients with rheumatoid arthritis previously untreated with methotrexate

Objective

To assess the effect of rituximab plus methotrexate (MTX) compared with MTX alone on patient‐reported outcomes (PROs) and health‐related quality of life (HRQOL) in patients with active early rheumatoid arthritis (RA) previously untreated with MTX.

Methods

Patients with active early RA were randomized to groups receiving placebo, rituximab 500 mg, or rituximab 1,000 mg. Rituximab was given by intravenous infusion on days 1 and 15. From week 24, patients with a Disease Activity Score in 28 joints–erythrocyte sedimentation rate of ≥2.6 were eligible for retreatment. Physical function was assessed by Health Assessment Questionnaire (HAQ) disability index (DI) and Short Form 36 (SF‐36) scores. Patients achieving a minimal clinically important difference (MCID) for PROs were determined. Additional PROs, including fatigue and pain, were assessed.

Results

A total of 748 patients were randomized and received the study drug. Patient characteristics were well balanced. At week 52, treatment with rituximab in both dose groups showed significant improvements in the HAQ DI compared to the MTX alone group (?0.905 and ?0.916 in the rituximab 500 mg plus MTX and 1,000 mg plus MTX groups, respectively, versus ?0.628 in the MTX alone group; P < 0.0001). Higher proportions of patients achieved MCID in the HAQ DI in the rituximab plus MTX groups compared to MTX alone. Treatment with rituximab plus MTX led to a significant reduction in the SF‐36 physical component summary for both rituximab dose groups, but did not show statistically significant differences in the SF‐36 mental component summary. Compared to the MTX alone group, both doses of rituximab plus MTX were associated with significant reductions in the patient global assessment of disease activity and pain, and a significantly higher improvement in Functional Assessment of Chronic Illness Therapy–Fatigue scores from baseline to 52 weeks.

Conclusions

Rituximab plus MTX was associated with significant improvement in physical function and HRQOL outcomes compared with MTX alone in patients previously untreated with MTX.

     

B cell reconstitution and T helper cell balance after rituximab treatment of active primary Sjögren's syndrome: A double‐blind,placebo‐controlled study

Objective

To assess the phenotype of reconstituting B cells after B cell depletion, and to assess the effect of reconstitution on the balance of Treg cells and effector T cells in patients with active primary Sjögren's syndrome (SS).

Methods

Twenty‐eight patients with primary SS were treated on days 1 and 15 with either rituximab (n = 19) or placebo (n = 9). The frequencies and absolute numbers of circulating B cell subsets, Treg cells, and effector T cells were examined in fresh blood samples by 4‐color flow cytometry at baseline and 5, 12, 24, 36, and 48 weeks after the first infusion. The results in rituximab‐treated patients were compared with those in patients receiving placebo and with those in age‐ and sex‐matched healthy controls (n = 10).

Results

At baseline, patients with primary SS displayed several abnormalities in B cell homeostasis, including a significant reduction of CD27+ B cells and expansion of CD27– B cells, compared with healthy controls. At week 48 after rituximab treatment, the majority of emerging B cells exhibited a phenotype of transitional B cells. Although recovery of CD27+ memory B cells was delayed after rituximab treatment, a significant increase in Ig class–switched memory B cells within the memory pool was observed. In addition, percentages and absolute numbers of Treg cells and effector T cells, as well as ratios of effector T cells to Treg cells, did not change significantly after rituximab treatment.

Conclusion

The characteristics of reconstituted B cells in patients with primary SS following depletion by rituximab treatment showed dominance of transitional B cells during the early recovery phase, which corresponds to bone marrow–derived repopulation. The depletion of B cells did not influence the balance of peripheral Treg cells and effector T cells.

     

Ofatumumab,a human anti‐CD20 monoclonal antibody,for treatment of rheumatoid arthritis with an inadequate response to one or more disease‐modifying antirheumatic drugs: Results of a randomized,double‐blind,placebo‐controlled,phase I/II study

Objective

To investigate the safety and efficacy of ofatumumab, a novel human anti‐CD20 monoclonal antibody (mAb), in patients with active rheumatoid arthritis (RA) whose disease did not respond to ≥1 disease‐modifying antirheumatic drug.

Methods

This combined phase I/II study investigated the safety and efficacy of 3 doses of ofatumumab. In part A (phase I), 39 patients received 2 intravenous (IV) infusions of ofatumumab (300 mg, 700 mg, or 1,000 mg) or placebo in a 4:1 ratio 2 weeks apart, using a specified premedication and infusion regimen. In part B (phase II), 225 patients received study treatment as per phase I in a 1:1:1:1 ratio. Safety was assessed by adverse events (AEs) and laboratory parameters. Efficacy was assessed by the American College of Rheumatology 20% criteria for improvement (ACR20), the Disease Activity Score in 28 joints, and the European League Against Rheumatism (EULAR) response criteria. B cell pharmacodynamics were also investigated.

Results

AEs were predominantly reported at the first infusion and were mostly mild to moderate in intensity. Rapid and sustained peripheral B cell depletion was observed in all dose groups. In phase II, patients in all ofatumumab dose groups had significantly higher ACR20 response rates (40%, 49%, and 44% for the 300 mg, 700 mg, and 1,000 mg doses, respectively) than did patients receiving placebo (11%) at week 24 (P < 0.001). Overall, 70% of patients receiving ofatumumab had a moderate or good response according to the EULAR criteria at week 24.

Conclusion

Our findings indicate that ofatumumab, administered as 2 IV infusions of doses up to 1,000 mg, is clinically effective in patients with active RA.

     

Management of nonresponse to rituximab in rheumatoid arthritis: Predictors and outcome of re‐treatment

Objective

A proportion of patients with rheumatoid arthritis (RA) have disease that fails to respond to an initial cycle of rituximab. Using highly sensitive flow cytometry (HSFC), it has been shown that most patients who do not exhibit a response, as measured using the European League Against Rheumatism (EULAR) criteria, have persistent circulating B cell levels at week 2 after initial treatment with rituximab. This study was undertaken to examine whether an additional cycle of rituximab would improve B cell depletion and clinical response in patients whose disease did not respond to the initial cycle.

Methods

Patients with RA (n = 158) were treated with a first cycle of rituximab (2 infusions of 1 gm each). Clinical responses were assessed using EULAR criteria, and patients were categorized as either first‐cycle responders or first‐cycle nonresponders. Baseline characteristics of first‐cycle nonresponders (n = 38) and first‐cycle responders (n = 65) with complete data were compared. First‐cycle nonresponders (n = 25) were treated with a second cycle of rituximab at least 6 months after the first cycle. HSFC was performed at baseline, immediately prior to the second infusion (week 2), 1 month after the second infusion (week 6), and then every 3 months for each cycle of rituximab. Complete B cell depletion was defined as being <0.0001 × 10⁹ cells/liter.

Results

At baseline, the number of preplasma cells was significantly higher in first‐cycle nonresponders than in first‐cycle responders (P = 0.003). Following the first infusion of the first cycle of rituximab, only 9% of first‐cycle nonresponders (3 of 34) exhibited complete depletion of B‐lineage cells, compared with 37% of first‐cycle responders (22 of 59) (P = 0.007). Following the first infusion of the second cycle of rituximab, 38% of first‐cycle nonresponders exhibited complete depletion. Twenty‐six weeks after the second cycle, there was a significant improvement in the Disease Activity Score in 28 joints, with 72% of patients exhibiting a EULAR response.

Conclusion

RA patients whose disease did not respond to an initial cycle of rituximab have higher circulating preplasma cell numbers at baseline and incomplete depletion. Our findings indicate that an additional cycle of rituximab administered prior to total B cell repopulation enhances B cell depletion and clinical responses.

     

The anti‐CD20 antibody rituximab reduces the Th17 cell response

Objective

Rituximab has been shown to be successful in the treatment of rheumatoid arthritis (RA), and this unexpected finding indicates that B cells have an important role in this disease. The present study was undertaken to investigate the mechanism of action of rituximab in RA.

Methods

Twelve patients with active RA were treated with rituximab. Disease activity was evaluated using the 28‐joint Disease Activity Score. Synovial biopsy samples obtained at baseline and 12 weeks after treatment initiation were analyzed by microarray, quantitative polymerase chain reaction, and immunohistochemistry. Peripheral blood mononuclear cells (PBMCs) from healthy volunteers and from 4 patients with X‐linked agammaglobulinemia were stimulated with the Th17‐inducing stimulus Candida albicans, and the response in the presence and absence of rituximab was examined.

Results

In RA patients, rituximab reduced expression of retinoic acid–related orphan receptor γt and interleukin‐22 (IL‐22) and numbers of Th17‐positive cells in synovial tissue, and this correlated with better clinical outcome. Rituximab did not affect tumor necrosis factor α (TNFα), Th1 cell, or Treg cell responses. Rituximab strongly reduced in vitro IL‐17 and IL‐22 production induced by C albicans. This effect was not observed in PBMCs from patients with X‐linked agammaglobulinemia.

Conclusion

Rituximab reduced the local Th17 response in RA patients, whereas it did not influence Th1 cell, Treg cell, or TNFα responses. The decreased Th17 response was associated with reduced inflammation and better clinical outcome. Moreover, inhibition of the Th17 response by rituximab was lost in the absence of B cells, providing evidence that the effects of rituximab are due to B cell depletion. These data demonstrate an unexpected role of B cells in the development of Th17 responses, which could possibly lead to B cell–based strategies for the treatment of Th17‐related autoimmune diseases.

     

Rituximab in the treatment of dermatomyositis: An open‐label pilot study

Objective

To test the hypothesis that B cells play a role in the pathophysiology of dermatomyositis (DM) by examining the effect of B cell depletion in patients with symptomatic DM. Patients were treated with rituximab, a CD20+ B cell–depleting monoclonal antibody.

Methods

This was an open‐label uncontrolled pilot trial in 7 adult patients with DM, 6 of whom had longstanding illness that was responding inadequately to a number of currently available immunosuppressive agents. All patients received 4 intravenous infusions of rituximab given at weekly intervals. Patients were followed up for up to 1 year without further treatment with rituximab. One patient was lost to followup. The principal efficacy outcome was muscle strength, measured by quantitative dynomometry.

Results

All 6 evaluable patients exhibited major clinical improvement, with muscle strength increasing over baseline by 36–113%. Maximal improvements in muscle strength occurred as early as 12 weeks after the initial infusion of rituximab. CD20+ B cells were effectively depleted in all patients by 12 weeks. Four patients experienced a return of symptoms that coincided with the return of B cells before the 52‐week end point. Two patients maintained their increased muscle strength at 52 weeks, and 1 of these patients maintained this strength even after the return of B cells. Other symptoms of DM, including rash, alopecia, and reduced forced vital capacity, improved markedly in patients with these symptoms. Rituximab was well tolerated, with no treatment‐related severe or serious adverse events during the observation period of this study.

Conclusion

This small open‐label study of DM patients treated with rituximab provided sufficiently encouraging results to justify a more formal evaluation of the value of B cell depletion therapy in the treatment of DM.

     

Remission of proliferative lupus nephritis following B cell depletion therapy is preceded by down‐regulation of the T cell costimulatory molecule CD40 ligand: An open‐label trial

Objective

Autoreactive B cells play a key role in tissue injury in systemic autoimmune disease, and therefore a treatment resulting in B cell depletion could have benefit. This open‐label study was undertaken to evaluate the efficacy of the anti‐CD20 monoclonal antibody rituximab in the treatment of lupus nephritis.

Methods

Lupus patients with active proliferative nephritis (4 with focal disease and 6 with diffuse disease) received rituximab (4 weekly infusions of 375 mg/m²) combined with oral prednisolone. Clinical, laboratory, and immunologic responses, including peripheral lymphocyte subsets measured by flow cytometry, were prospectively assessed at monthly intervals for 12 months. Complete remission of nephritis was defined as normal serum creatinine and albumin levels, inactive urine sediment, and 24‐hour urinary protein <500 mg. Partial remission was defined as >50% improvement in all renal parameters that were abnormal at baseline.

Results

B cell depletion lasted from 1 month to 7 months and was well tolerated. Partial remission was achieved in 8 of 10 patients within a median of 2 months (range 1–4 months); in 5 of them, complete remission was subsequently established (at a median of 3 months from baseline), and it was sustained at 12 months in 4. As early as 1 month from baseline, the expression of the costimulatory molecule CD40 ligand on CD4+ T cells was decreased by 4‐fold, and it was almost blocked when partial remission was clinically evident. The expression of T cell activation markers CD69 and HLA–DR was significantly decreased at time points when partial remission was observed, and was further decreased during complete remission. In contrast, in patients who did not exhibit a response or when relapse was detected in patients in whom an initial remission had been achieved, such decreases were not prominent. Serum concentrations of double‐stranded DNA autoantibodies were decreased in all patients, regardless of clinical outcome.

Conclusion

Following B cell depletion, clinical remission of lupus nephritis is associated with a decrease in T helper cell activation, suggesting an additional role for B cells, independent of autoantibody production, in promoting disease. A controlled trial to confirm these promising clinical results is warranted.

     

The efficacy and safety of rituximab in patients with active rheumatoid arthritis despite methotrexate treatment: Results of a phase IIB randomized,double‐blind,placebo‐controlled,dose‐ranging trial

Objective

To examine the efficacy and safety of different rituximab doses plus methotrexate (MTX), with or without glucocorticoids, in patients with active rheumatoid arthritis (RA) resistant to disease‐modifying antirheumatic drugs (DMARDs), including biologic agents.

Methods

A total of 465 patients were randomized into 9 treatment groups: 3 rituximab groups (placebo [n = 149], 500 mg [n = 124], or 1,000 mg [n = 192] on days 1 and 15) each also taking either placebo glucocorticoids, intravenous methylprednisolone premedication, or intravenous methylprednisolone premedication plus oral prednisone for 2 weeks. All patients received MTX (10–25 mg/week); no other DMARDs were permitted.

Results

Significantly more patients who received 2 500‐mg or 2 1,000‐mg infusions of rituximab met the American College of Rheumatology 20% improvement criteria (achieved an ACR20 response) at week 24 (55% and 54%, respectively) compared with placebo (28%; P < 0.0001). ACR50 responses were achieved by 33%, 34%, and 13% of patients, respectively (P < 0.001), and ACR70 responses were achieved by 13%, 20%, and 5% of patients (P < 0.05). Changes in the Disease Activity Score in 28 joints (−1.79, −2.05, −0.67; P < 0.0001) and moderate to good responses on the European League Against Rheumatism criteria (P < 0.0001) reflected the ACR criteria responses. Glucocorticoids did not contribute significantly to the primary efficacy end point, ACR20 response at 24 weeks. Intravenous glucocorticoid premedication reduced the frequency and intensity of first infusion–associated events; oral glucocorticoids conferred no additional safety benefit. Rituximab was well tolerated; the type and severity of infections was similar to those for placebo.

Conclusion

Both rituximab doses were effective and well tolerated when added to MTX therapy in patients with active RA. The primary end point (ACR20 response) was independent of glucocorticoids, although intravenous glucocorticoid premedication improved tolerability during the first rituximab infusion.

     

Delayed acquisition of somatic hypermutations in repopulated IGD+CD27+ memory B cell receptors after rituximab treatment

Objective

Transient B cell depletion by rituximab has been used with clinical efficacy in the treatment of patients with rheumatoid arthritis (RA). Previous studies of B cell repopulation have shown long‐term numerical reduction in memory B cells. Non–class‐switched IgD+CD27+ memory B cells, in particular, repopulate slowly. This study was undertaken to determine whether mutational acquisition in individual B cell receptors in repopulating class‐switched and non–class‐switched memory B cells is affected by rituximab.

Methods

Cells obtained from 16 RA patients, 4 healthy donors, and 3 patients who underwent allogeneic stem cell transplantation (ASCT) were analyzed using single B cell sorting followed by nested polymerase chain reaction and Ig V_H3 sequencing.

Results

There was a delayed acquisition of mutations in Ig receptors of IgD+ memory B cells over a period of 6 years after a single course of rituximab. One year after rituximab treatment, 84% of single repopulating IgD+CD27+ B cells were unmutated, and no highly mutated Ig receptors were found (compared with 52% before therapy). Over time, increasing numbers of mutations were detected. Even 6 years after rituximab treatment, however, mutations in IgD+ memory B cells were still significantly reduced. In contrast, class‐switched memory B cells repopulated with quantitatively normal mutations. In comparison, in patients undergoing ASCT, IgD+ memory cells repopulated earlier with higher mutations in Ig receptors.

Conclusion

Our data suggest that IgD+ memory B cells are particularly susceptible to the effects of rituximab, with delayed acquisition of mutations in their Ig receptors still evident 6 years after a single course of rituximab. Our findings indicate that these cells have different requirements for mutational acquisition compared with class‐switched memory B cells.

     

Immunization responses in rheumatoid arthritis patients treated with rituximab: Results from a controlled clinical trial

Objective

To examine immunization responses in patients with rheumatoid arthritis (RA) treated with rituximab and to investigate the effects of rituximab‐induced CD20+ B cell depletion on immune responses to tetanus toxoid (T cell–dependent antigen), pneumococcal polysaccharide (T cell–independent antigen), and keyhole limpet hemocyanin (KLH) (neoantigen) and on delayed‐type hypersensitivity (DTH).

Methods

In a controlled trial, we enrolled 103 patients with active RA receiving a stable dose of methotrexate (MTX). Tetanus toxoid, pneumococcal polysaccharide, and KLH vaccines as well as a Candida albicans skin test were administered to 1 group of patients receiving rituximab plus MTX (called rituximab‐treated patients) for 36 weeks and to 1 group of patients receiving MTX alone for 12 weeks. The primary end point was the proportion of patients with a ≥4‐fold rise in antitetanus IgG levels. Antitetanus, antipneumococcal, and anti‐KLH serum IgG levels were measured prior to and 4 weeks following vaccine administration. The DTH response to C albicans was measured 2–3 days following placement.

Results

Responses to tetanus toxoid vaccine (≥4‐fold rise) were similar in both groups (39.1% of rituximab‐treated patients and 42.3% of patients treated with MTX alone). The ability to maintain a positive DTH response to the C albicans skin test was comparable in both groups (77.4% of rituximab‐treated patients and 70% of patients treated with MTX alone), showing no effect of rituximab treatment. Rituximab‐treated patients had decreased responses to pneumococcal polysaccharide vaccine (57% of patients had a 2‐fold rise in titer in response to ≥1 serotype, compared with 82% of patients treated with MTX alone) and to KLH vaccine (47% of patients had detectable anti‐KLH IgG, compared with 93% of patients treated with MTX alone).

Conclusion

Recall responses to the T cell–dependent protein antigen tetanus toxoid as well as DTH responses were preserved in rituximab‐treated RA patients 24 weeks after treatment. Responses to neoantigen (KLH) and T cell–independent responses to pneumococcal vaccine were decreased, but many patients were able to mount responses. These data suggest that polysaccharide and primary immunizations should be administered prior to rituximab infusions to maximize responses.

     

Rituximab therapy leads to rapid decline of serum IgG4 levels and prompt clinical improvement in IgG4‐related systemic disease

Objective

Patients with IgG4‐related systemic disease (IgG4‐RSD) frequently show an incomplete response to treatment with glucocorticoids and traditional disease‐modifying antirheumatic drugs (DMARDs). B lymphocyte depletion is a therapeutic strategy known to be effective for pemphigus vulgaris, an autoimmune condition mediated by IgG4 autoantibodies. This study was performed to assess the clinical and serologic responses to B lymphocyte depletion therapy with rituximab in patients with IgG4‐RSD.

Methods

Four patients with IgG4‐RSD were treated with 2 intravenous doses (1 gram each) of rituximab. Clinical improvement was assessed by monitoring the tapering/discontinuation of prednisone and DMARDs, and by measuring the serum concentrations of B lymphocytes, immunoglobulins, and IgG subclasses before and after therapy.

Results

Clinical features of IgG4‐RSD in these 4 patients included autoimmune pancreatitis, sclerosing cholangitis, lymphoplasmacytic aortitis, salivary gland involvement, orbital pseudotumor, and lacrimal gland enlargement. The 3 patients with elevated serum IgG and IgG4 levels at baseline had a mean IgG concentration of 2,003 mg/dl (normal range 600–1,500 mg/dl) and a mean IgG4 concentration of 2,160 mg/dl (normal range 8–140 mg/dl). Among these patients, the serum IgG4 concentrations declined by a mean of 65% within 2 months of rituximab administration. All 4 patients demonstrated striking clinical improvement within 1 month of the initiation of rituximab therapy, and tapering or discontinuation of their treatment with prednisone and DMARDs was achieved in all 4 patients. A decrease in IgG concentration was observed for the IgG4 subclass only.

Conclusion

Treatment with rituximab led to prompt clinical and serologic improvement in these patients with refractory IgG4‐RSD, and is a viable treatment option for this condition. The decline in serum IgG4 concentrations was substantially steeper than that of the autoantibody concentrations in immune‐mediated conditions in which rituximab is effective, such as in rheumatoid arthritis. In addition, the reduction in IgG‐subclass levels appeared to be specific for IgG4. The swift improvement of IgG4‐RSD suggests that rituximab achieves its effects in IgG4‐RSD by depleting the pool of B lymphocytes that replenish short‐lived IgG4‐secreting plasma cells.

     

Induction of remission by B lymphocyte depletion in eleven patients with refractory antineutrophil cytoplasmic antibody–associated vasculitis

Objective

To assess the clinical effects of rituximab therapy in patients with antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis (AAV).

Methods

The study group comprised 11 patients who had active AAV despite receiving maximally tolerated doses of cyclophosphamide or had contraindications for cyclophosphamide use. All patients had ANCA reactive against proteinase 3. The patients received rituximab infusions and glucocorticoids to induce remission. Three patients also received plasma exchange. No other immunosuppressive agents were used. Glucocorticoids were tapered as soon as control of disease activity was achieved. Disease activity was monitored using the Birmingham Vasculitis Activity Score, modified for Wegener's granulomatosis.

Results

Rituximab therapy was well tolerated by all patients, and adverse events were rare. Following the rituximab infusions, circulating B lymphocytes became undetectable, and ANCA titers decreased significantly. Remission was achieved in all patients and was maintained while B lymphocytes were absent.

Conclusion

The ability to achieve stable remissions with rituximab in patients with AAV refractory to conventional therapy suggests that B lymphocyte depletion may be a safe, effective, mechanism‐based treatment modality for treatment of patients with these conditions.