Efficacy and safety of obinutuzumab in systemic lupus erythematosus patients with secondary non-response to rituximab.

OBJECTIVES: Secondary inefficacy with infusion reactions and anti-drug antibodies (secondary non-depletion nonresponse, 2NDNR) occurs in 14% of SLE patients receiving repeated rituximab courses. We evaluated baseline clinical characteristics, efficacy and safety of obinutuzumab, a next-generation humanized type-2 anti-CD20 antibody licensed for haematological malignancies in SLE patients with 2NDNR to rituximab. METHODS: We collated data from SLE patients receiving obinutuzumab for secondary non-response to rituximab in BILAG centres. Disease activity was assessed using BILAG-2004, SLEDAI-2K and serology before, and 6 months after, obinutuzumab 2× 1000 mg infusions alongside methylprednisolone 100 mg. RESULTS: All nine patients included in the study received obinutuzumab with concomitant oral immunosuppression. At 6 months post-obinutuzumab, there were significant reductions in median SLEDAI-2K from 12 to 6 (P = 0.014) and total BILAG-2004 score from 21 to 2 (P = 0.009). Complement C3 and dsDNA titres improved significantly (both P = 0.04). Numerical, but not statistically significant improvements were seen in C4 levels. Of 8/9 patients receiving concomitant oral prednisolone at baseline (all >10 mg/day), 5/8 had their dose reduced at 6 months. Four of nine patients were on 5 mg/day and were in Lupus Low Disease Activity State following obinutuzumab. After obinutuzumab, 6/9 patients with peripheral B cell data achieved complete depletion, including 4/4 assessed with highly sensitive assays. Of the nine patients, one obinutuzumab non-responder required CYC therapy. One unvaccinated patient died from COVID-19. CONCLUSIONS: Obinutuzumab appears to be effective and steroid-sparing in renal and non-renal SLE patients with secondary non-response to rituximab. These patients have severe disease with few treatment options but given responsiveness to B cell depletion, switching to humanized type-2 anti-CD20 therapy is a logical approach.

Real-world experience of effectiveness of non-medical switch from originator to biosimilar rituximab in rheumatoid arthritis.

OBJECTIVE: To evaluate the impact of non-medical switch from rituximab originator (RTX-O) to biosimilar (RTX-B) in patients with RA. METHODS: Between October 2017 and October 2019, all patients on RTX-O in our centre requiring re-treatment were switched to RTX-B unless declined by the patient or specified by the treating clinician. Switch strategy effectiveness was assessed retrospectively using DAS28-CRP(3) and RTX retention, with patients remaining on RTX-O as a comparator group. RESULTS: The number of patients switching to RTX-B was 255/337 (75.7%) while 82 (24.3%) remained on RTX-O. There was no difference in DAS28-CRP(3) 4 months post-RTX-B switch vs the same time point post-RTX-O previous cycle (paired data available in 60%). Eighteen-month retention estimates were 75.6% (95% CI: 69.4, 80.7%) for RTX-B group and 82.3% (95% CI: 70.4, 89.8%) for RTX-O [adjusted hazard ratio 1.52 (95% CI: 0.85, 2.73)]. The number of patients who discontinued RTX-B for loss of effectiveness (LOE) was 42/255 (16.5%), five (2.0%) for adverse effects (AEs). Risk of RTX-B discontinuation was associated with comorbidities and ≥2 previous biologic DMARDs. Risk of adverse outcome RTX cessation was associated with comorbidities, and reduced risk with number of previous RTX-O cycles and pre-switch cycle B cell depletion. The number of patients who switched back to RTX-O was 34/255 (13.3%) (LOE: 30, AEs: 4), while 13/255 (5.1%) started other biologic/targeted synthetic DMARDs. Of patients who switched back for LOE, 28/30 remained on RTX-O at a mean 7.7 months follow-up. CONCLUSION: Non-medical switch to RTX-B was largely effective. Factors associated with RTX-B discontinuation, including comorbidities, previous biologic DMARDs, and RTX-O treatment history, may inform switch decisions. Most patients who switched back to RTX-O for LOE remained on treatment at short-term follow-up.

Effect of rituximab or tumour necrosis factor inhibitors on lung infection and survival in rheumatoid arthritis-associated bronchiectasis.

OBJECTIVE: To evaluate rituximab (RTX) in patients with RA-associated bronchiectasis (RA-BR) and compare 5-year respiratory survival between those treated with RTX and TNF inhibitors (TNFi). METHODS: A retrospective observational cohort study of RA-BR in RTX or TNFi-treated RA patients from two UK centres over 10 years. BR was assessed using number of infective exacerbation/year. Respiratory survival was measured from therapy initiation to discontinuation either due to lung exacerbation or lung-related deaths. RESULTS: Of 800 RTX-treated RA patients, 68 had RA-BR (prevalence 8.5%). Post-RTX, new BR was diagnosed in 3/735 patients (incidence 0.4%). At 12 months post-Cycle 1 RTX, 21/68 (31%) patients had fewer exacerbations than the year pre-RTX, 36/68 (53%) remained stable and 11/68 (16%) had increased exacerbations. The rates of exacerbation improved after Cycle 2 and stabilized up to 5 cycles. Of patients who received ≥2 RTX cycles (n = 60), increased exacerbations occurred in 7/60 (12%) and were associated with low IgG, aspergillosis and concurrent alpha-1-antitrypsin deficiency. Overall, 8/68 (11.8%) patients discontinued RTX while 15/46 (32.6%) discontinued TNFi due to respiratory causes. The adjusted 5-year respiratory survival was better in RTX-treated compared with TNFi-treated RA-BR patients; HR 0.40 (95% CI 0.17, 0.96); P =0.041. CONCLUSION: The majority of RTX-treated RA-BR patients had stable/improved pulmonary symptoms in this long-term follow-up. In isolated cases, worsening of exacerbation had definable causes. Rates of discontinuation due to adverse lung outcomes were better for RTX than a matched TNFi cohort. RTX is an acceptable therapeutic choice for RA-BR if a biologic is needed.

Effect of rituximab on the progression of rheumatoid arthritis-related interstitial lung disease: 10 years' experience at a single centre.

Objective: To evaluate the effect of rituximab (RTX) in patients with RA-related interstitial lung disease (RA-ILD) and identify factors associated with outcome after treatment. Methods: An observational study of patients with RA-ILD was conducted from a cohort of RTX-treated RA patients in a single centre for >10 years. Progression was defined by any of the following: a decrease of pre-RTX forced vital capacity (FVC) >10% or diffusion capacity of carbon monoxide (DLCO) >15% predicted, worsening of the ILD score or death from progressive ILD. Results: Of 700 RA patients treated with RTX, 56 had RA-ILD (prevalence = 8%). After RTX, new ILD was diagnosed in 3/700 patients (incidence = 0.4%). Data for lung assessment were available for 44/56 patients. The median relative change pre- and post-RTX for FVC were -2.4% and +1.2% ( P = 0.025) and for DLCO were -4.4% and -1.3% ( P = 0.045). Post-RTX, 23/44 (52%) were stable and 7/44 (16%) had improved. Of the 14 (32%) with ILD that progressed, 9/56 (16%) were deaths due to progressive ILD. Factors associated with ILD progression were radiologic pattern of usual interstitial pneumonia, a previous history of lung progression and pre-RTX DLCO <46% predicted. Of those whose ILD progressed, 11/14 (79%) had severe ILD before RTX [median DLCO 42% predicted (interquartile range 41-49)]. Conclusion: In this cohort of patients where RTX was given for arthritis, most patients with ILD pre-RTX remained stable/improved after treatment over a prolonged follow-up period. Patients who deteriorated/died had the most severe ILD pre-RTX, suggesting the drug was not contributory. RTX appears to be an acceptable therapeutic choice for patients with RA-ILD and further studies are warranted.

An extra dose of rituximab improves clinical response in rheumatoid arthritis patients with initial incomplete B cell depletion: a randomised controlled trial.

OBJECTIVES: Since clinical non-response to 2×1000 mg rituximab has previously been found to be associated with incomplete B cell depletion, we determined, in a randomised controlled proof of concept study, whether patients with initial incomplete B cell depletion would benefit from an additional infusion of rituximab at week 4. METHODS: Patients with active rheumatoid arthritis despite methotrexate received a first infusion of rituximab 1000 mg and were tested for persistent B cells using highly sensitive flow cytometry on day 15. All received a second infusion of 1 g (according to license), but patients with persistent B cells were subsequently randomised double-blind to receive, 2 weeks later, either a third infusion of 1000 mg rituximab or placebo. Clinical response was determined by European League Against Rheumatism (EULAR) and American College of Rheumatology (ACR) criteria. RESULTS: Baseline characteristics were balanced between groups. Treatment with 3×1000 mg rituximab resulted in significantly greater depletion (lower B cell and plasmablast numbers between 8 and 28 weeks) paralleled by significantly better EULAR and ACR20 response rates at 40 weeks (p=0.035 and p=0.027, respectively) and 52 weeks (p=0.021 and p=0.043, respectively) compared with 2×1000 mg. Immunoglobulin titres remained stable in both arms, and adverse event rates were balanced. CONCLUSIONS: In rituximab-treated patients with incomplete B cell depletion (predictive of poor response), an extra 1000 mg infusion of rituximab at 4 weeks produced both better depletion and clinical responses than placebo with no worsening of safety. Degree of depletion is an important, but modifiable, determinant of response.

Repeat cycles of rituximab on clinical relapse in ANCA-associated vasculitis: identifying B cell biomarkers for relapse to guide retreatment decisions.

OBJECTIVE: To assess clinical and B cell biomarkers to predict relapse after rituximab in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) using retreatment on clinical relapse strategy. METHODS: 35 patients with AAV received treatment with 2×1000 mg rituximab, repeated on clinical relapse (up to 5 cycles). Disease activity was assessed by Birmingham Vasculitis Activity Score (BVAS) and peripheral B cell subsets using highly sensitive flow cytometry (HSFC) as previously described; both performed at baseline and every 3 months. RESULTS: Response rates were high: >83%, with median time-to-relapse of 82 weeks for cycle 1 (C1) and >54 weeks for all cycles. Prior to rituximab, AAV was characterised by naïve B-lymphopenia compared to healthy controls. This dysregulation was more marked in patients with raised C-reactive protein (CRP) (p<0.05). In C1, no clinical feature predicted relapse. However, repopulation of naïve B cell at 6 months was associated with a reduced risk of relapse (HR: 0.326, 95% 0.114 to 0.930, p=0.036). Relapse rates at 12 and 18 months were 0% and 14% with naïve repopulation at 6 months, and 31% and 54% without naïve repopulation. CONCLUSIONS: Responses to B cell depletion therapy are long-lasting and relapse post-treatment may be predicted by absence of naïve B cell repopulation at 6 months. Naïve B-lymphopenia may be a biomarker of disease activity in AAV.

Poly-Refractory Rheumatoid Arthritis: An Uncommon Subset of Difficult to Treat Disease With Distinct Inflammatory and Noninflammatory Phenotypes.

OBJECTIVE: To investigate the prevalence of poly-refractory rheumatoid arthritis (RA) defined as failure of all biological (b)/targeted synthetic (ts)-disease-modifying drugs (DMARDs). To further investigate whether patients with persistent inflammatory refractory RA (PIRRA) and noninflammatory refractory RA (NIRRA), determined by objective ultrasound (US) synovitis, have distinct clinical phenotypes in both EULAR difficult-to-treat RA (D2T-RA) and poly-refractory RA groups. METHODS: A cross-sectional study of 1,591 patients with RA on b/tsDMARDs that evaluated D2T-RA criteria and subclassified as poly-refractory if inefficacy/toxicity to at least one drug of all classes. PIRRA was defined if US synovitis in one or more swollen joint and NIRRA if absent. Univariate tests and multivariate logistic regression were conducted to investigate factors associated with poly-refractory, PIRRA, and NIRRA phenotypes. RESULTS: 122 of 1,591 were excluded due to missing data. 247 of 1,469 (16.8%) had D2T-RA and only 40 of 1,469 (2.7%) poly-refractory RA. This latter group had higher disease activity score 28 C-reactive protein (CRP) (median 5.4 vs 5.02, P < 0.05), CRP levels (median 13 vs 5 mg/l, P < 0.01), and smoking (ever) rates (20% vs 4%, P < 0.01) compared with other D2T patients. Smoking was associated with poly-refractory RA (odds ratio 5.067, 95% CI 1.774-14.472, P = 0.002). Of 107 patients with D2T-RA with recent US, 61 (57%) were PIRRA and 46 (43%), NIRRA. Patients with NIRRA had elevated body mass index (median 30 vs 26, P < 0.001) and higher fibromyalgia prevalence (15% vs 3%, P < 0.05), lower swollen joint count (median: 2 vs 5, P < 0.001), and lower CRP levels (5 vs 10, P < 0.01). CONCLUSION: Only 2.7% of D2T-RA failed all classes of b/tsDMARDs. Among D2T-RA, less than 60% had objective signs of inflammation, representing a target for innovative strategies.

The time of equipoise on the use of biological DMARDs in for inflammatory arthritis during pregnancy is finally over: a reappraisal of evidence to optimise pregnancy management.

Active inflammatory arthritis in pregnancy is associated with an increased risk of adverse pregnancy outcomes. Treatment of active inflammation and maintenance of low disease activity with medication reduces these risks. Therapeutic decisions on disease-modifying antirheumatic drugs (DMARDs) in pregnancy are complicated by safety concerns, which have led to inappropriate withdrawal of treatment and consequential harm to mother and fetus. Studies of inflammatory arthritis in pregnancy have consistently shown minimal safety concerns with the use of biological DMARDs and an increased risk of disease flare with discontinuation of biological DMARDs. It is our opinion that during pregnancy, the benefits of disease control with biological DMARDs, when required in addition to conventional synthetic DMARDs, outweigh the risks. In this Series paper, we review the reasons for reconsideration of equipoise and propose an agenda for future research to optimise the use of biological DMARDs in inflammatory arthritis during pregnancy.

Breakthrough SARS-CoV-2 infections and prediction of moderate-to-severe outcomes during rituximab therapy in patients with rheumatic and musculoskeletal diseases in the UK: a single-centre cohort study.

Background: Concerns have been raised regarding the reduced immunogenicity of vaccines against COVID-19 in patients with autoimmune diseases treated with rituximab. However, the incidence and severity of breakthrough infections in unbiased samples of patients with specific rheumatic and musculoskeletal diseases are largely unknown. We aimed to assess the incidence of breakthrough SARS-CoV-2 infection, compare rates of moderate-to-severe COVID-19 with any severe infection event, and evaluate predictors of moderate-to-severe COVID-19 outcomes in patients treated with rituximab. Methods: We did a retrospective cohort study in all rituximab-treated patients with rheumatic and musculoskeletal diseases in a single centre in Leeds, UK between March 1, 2020 (the index date), and April 1, 2022. Adults aged 18 years and older, who fulfilled classification criteria for established rheumatic and musculoskeletal diseases, and received therapy with at least one rituximab infusion between Sept 1, 2019 (6 months before the pandemic in the UK), and April 1, 2022, were eligible for inclusion in the study. SARS-CoV-2 infection was defined by antigen test or PCR. COVID-19 outcomes were categorised as mild (from ambulatory to hospitalised but not requiring oxygen support) or moderate-to-severe (hospitalised and requiring oxygen support or death). The primary outcome was breakthrough COVID-19 infection, which was defined as an infection occurring 14 days or more after the second vaccine dose. Predictors of moderate-to-severe COVID-19 outcomes were analysed using Cox regression proportional hazards. Findings: Of the 1280 patients who were treated with at least one cycle of rituximab since Jan 1, 2002, 485 (38%) remained on rituximab therapy on April 1, 2022. Of these patients, 400 fulfilled all inclusion criteria and were included in our final analysis. The mean age at the index date was 58·9 years (SD 14·6), 288 (72%) of 400 patients were female and 112 (28%) were male, 333 (83%) were White, and 110 (28%) had two or more comorbidities. 272 (68%) of 400 patients had rheumatoid arthritis, 48 (12%) had systemic lupus erythematosus, 48 (12%) had anti-neutrophil cytoplasmic antibody-associated vasculitis, and 46 (12%) had other rheumatic and musculoskeletal diseases. During the study, 798 rituximab cycles were administered. Of the 398 (>99%) of 400 patients with vaccine data, 372 (93%) were fully vaccinated. Over the 774·6 patient-years of follow-up, there was an incremental increase in all SARS-CoV-2 severity types over the three pandemic phases (wild-type or alpha, delta, and omicron), but most infections were mild. The rates of moderate-to-severe COVID-19 were broadly similar across these three variant phases. Of 370 patients who were fully vaccinated and with complete data, 110 (30%) had all severity type breakthrough COVID-19, 16 (4%) had moderate-to-severe breakthrough COVID-19, and one (<1%) died. In the post-vaccination phase (after Dec 18, 2020), the incidence rates of all severity type and moderate-to-severe COVID-19 were substantially lower in those who were fully vaccinated compared with unvaccinated or partially vaccinated individuals (22·83 per 100 person-years [95% CI 18·94-27·52] in those who were fully vaccinated vs 89·46 per 100 person-years [52·98-151·05] in those who were partially vaccinated or unvaccinated for infections of all severities, and 3·32 per 100 person-years [2·03-5·42] in those who were fully vaccinated vs 25·56 per 100 person-years [9·59-68·10] in those who were partially vaccinated or unvaccinated for moderate-to-severe infections). The rate of moderate-to-severe COVID-19 was broadly similar to other severe infection events in this cohort (5·68 per 100 person-years [95% CI 4·22-7·63]). In multivariable Cox regression analysis, factors associated with an increased risk of moderate-to-severe COVID-19 were the number of comorbidities (hazard ratio 1·46 [95% CI 1·13-1·89]; p=0·0037) and hypogammaglobulinaemia (defined by a pre-rituximab IgG concentration of <6 g/L; 3·22 [1·27-8·19]; p=0·014). This risk was reduced with each vaccine dose received (0·49 [0·37-0·65]; p<0·0001). Other factors, including concomitant prednisolone use, rituximab-associated factors (eg, rituximab dose and time to vaccination since last rituximab dose), and vaccine-associated factors (eg, vaccine type and peripheral B-cell depletion) were not predictive of moderate-to-severe COVID-19 outcomes. Interpretation: This study presented detailed analyses of rituximab-treated patients during various phases of the COVID-19 pandemic. In later stages of the pandemic, the SARS-CoV-2 breakthrough infection rate was high but severe COVID-19 rates were similar to any severe infection event rate in patients who were vaccinated. The risk-benefit ratio might still favour rituximab in vaccinated patients with severe rheumatic and musculoskeletal diseases who have few other treatment options. Increased vigilance is needed in the presence of comorbidities and hypogammaglobulinaemia for all infection types. Funding: Wellcome Trust and Eli Lilly.

Reduced-dose rituximab in rheumatoid arthritis: efficacy depends on degree of B cell depletion.

OBJECTIVE: Studies comparing 500 mg rituximab and 1,000 mg rituximab doses in rheumatoid arthritis have yielded conflicting data on clinical outcomes, but in all of these studies a subgroup of patients has had excellent responses at the lower dose. Historically, it was considered that rituximab uniformly depleted B cells at both doses. Using highly sensitive assays, we have shown that B cell depletion is variable and predictive of clinical response. Using the same techniques, we undertook the present study to test the hypothesis that the level of B cell depletion, rather than the rituximab dose, determines clinical response. METHODS: Nineteen patients were treated with two 500-mg infusions of rituximab, and 61 patients were treated with two 1,000-mg infusions of rituximab. Highly sensitive flow cytometry was performed at 0, 2, 6, 14, and 26 weeks. European League Against Rheumatism (EULAR) response rates at 6 months were compared between patients with and those without complete depletion at each dose. RESULTS: The median B cell count was numerically higher at all time points following therapy in the 500 mg rituximab group. Twenty-five percent of patients in the 500 mg rituximab group had complete depletion at 2 weeks, compared with 49% of those in the 1,000 mg rituximab group. Complete depletion at 2 weeks after treatment with 500 mg rituximab was associated with lower baseline preplasma cell counts (P = 0.047). Most patients responded after either dose, but response was related to B cell depletion. Notably, in the 500 mg rituximab group all patients with complete depletion had a EULAR good response (P = 0.011). CONCLUSION: This pilot study suggests that the degree of B cell depletion, rather than the dose of rituximab, determines clinical response. It may be possible to predict which patients will respond to lower-dose rituximab, and this may allow more cost-effective treatment.

B cell biomarkers of rituximab responses in systemic lupus erythematosus.

OBJECTIVE: Rituximab appears to be effective in many studies of systemic lupus erythematosus (SLE), with variable initial clinical response and time to relapse. However, results of a randomized controlled trial of rituximab were negative. This study was undertaken to evaluate the effectiveness of rituximab in SLE, using highly sensitive flow cytometry (HSFC), which can define B cell numbers 50-100 times lower than conventional techniques and predicts responses in rheumatoid arthritis. METHODS: Thirty-nine patients with active SLE were started on a standard regimen of rituximab with intravenous and oral steroids. Clinical response and relapse were defined using the British Isles Lupus Assessment Group (BILAG) index with criteria for major clinical response, partial clinical response, and nonresponse. HSFC, including analysis of B cell subsets, was performed. RESULTS: There was a significant reduction from baseline in global BILAG score at all time points analyzed (P<0.0001), and major clinical response and partial clinical response rates were 51% and 31%, respectively. Time to relapse was highly variable. Fifty percent of the patients relapsed after 6-18 months (earlier relapse); the remainder relapsed at a slower rate (later relapse). B cell depletion and repopulation were variable and were predictive of these clinical outcomes. There was a persistent B cell presence in 21 patients after 2 infusions of rituximab, which included all 7 patients with no response (P=0.012 versus patients with complete depletion of B cells). Memory B cell (P=0.02) and plasmablast (P<0.001) repopulation after 26 weeks was markedly faster in patients with earlier relapse versus patients with later relapse. CONCLUSION: Our findings indicate that rituximab is effective in SLE, and clinical responses are supported by close correlation with B cell numbers. HSFC is a valuable tool in the assessment and prediction of response in SLE.

Single-centre experience of refractory rheumatoid arthritis.

Objectives: The aim was to evaluate the proportion of RA patients who are refractory to multiple targeted therapies (TTs) in a real-world cohort of patients in a tertiary rheumatology referral centre, to describe patterns of drug sequencing associated with the development of refractory RA (RefRA) and to identify whether there is a subgroup of RefRA patients in whom successive drugs have shown primary lack of efficacy. Methods: Patients at a single centre were defined as refractory if they had failed two or more classes of TT and were identified from a dedicated TT clinic database. Reasons for drug failure were recorded, and patients were categorized pragmatically as having mild [failure of two biologic DMARD (bDMARD) classes], moderate [failure of at least three bDMARD classes] or severe [failure of at least two bDMARD classes and JAK inhibitor] refractory disease. Results: One hundred and seventy-two patients were identified as RefRA (>10% of our TT-exposed cohort); median [interquartile range (IQR)] TT exposures of four (two), 81.5% female, 82% seropositive, mean (s.d.) age of 63 (12.3) years. Detailed analysis of 60 patients showed a median (IQR) disease duration of 22 (10.75) years, median (IQR) time from diagnosis to initiation of first TT of 5 (10) years, and mean (s.d.) baseline DAS28CRP before starting first-line TT of 5.91 (0.84). Among RefRA patients, 15% were severely refractory, and 6% had demonstrated no clinical response to any TT. Conclusion: A small proportion of patients have true RefRA. Most patients fail multiple therapies owing to a combination of inefficacy and adverse events.

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.

A Personalized Rituximab Retreatment Approach Based on Clinical and B-Cell Biomarkers in ANCA-Associated Vasculitis.

Background: Time to relapse after rituximab for the treatment of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is variable, and optimal retreatment strategy has remained unclear. In AAV following rituximab induction, the study objective was to evaluate clinical and B-cell predictors of relapse in order to develop a retreatment algorithm. Methods: A retrospective observational study was conducted in 70 rituximab-treated ANCA-associated vasculitis patients followed up for over 10 years. Complete response (CR) was defined as Birmingham Vasculitis Activity Score v3.0 = 0. Retreatment was given on clinical relapse, defined as new features or worsening of persistent disease (not by biomarker status). Peripheral B-cell subsets were measured using highly sensitive flow cytometry. Predictors were tested using multivariable Cox regression. Results: Median time to retreatment for cycles 1-5 were 84, 73, 67, 60, and 73 weeks. Over 467 patient-years follow-up, 158 relapses occurred in 60 patients; 16 (in 15 patients) were major (renal = 7, neurological = 4, ENT = 3, and respiratory = 2). The major-relapse rate was 3.4/100 patient-years. In multivariable analysis, concomitant immunosuppressant [HR, 0.48 (95% CI, 0.24-0.94)], achieving CR [0.24 (0.12-0.50)], and naïve B-cell repopulation at 6 months [0.43 (0.22-0.84)] were associated with longer time to relapse. Personalized retreatment using these three predictors in this cohort would have avoided an unnecessary fixed retreatment in 24% of patients. Area under the receiver operating characteristic for prediction of time to relapse was greater if guided by naïve B-cell repopulation than if previously evaluated ANCA and/or CD19+ cells return at 6 months had been used, 0.82 and 0.53, respectively. Conclusion: Our findings suggest that all patients should be coprescribed oral immunosuppressant. Those with incomplete response or with absent naïve B cells should be retreated at 6 months. Patients with complete response and naïve repopulation should not receive fixed retreatment. This algorithm could reduce unnecessary retreatment and warrant investigation in clinical trials.

Biologic Sequencing in Systemic Lupus Erythematosus: After Secondary Non-response to Rituximab, Switching to Humanised Anti-CD20 Agent Is More Effective Than Belimumab.

Background: Rituximab is commonly used for systemic lupus erythematosus (SLE) but secondary non-depletion and non-response (2NDNR) associated with anti-drug antibodies is a notable problem with repeat rituximab cycles. Other B cell-targeted therapies include other anti-CD20 monoclonal antibodies or belimumab. Objective: To compare efficacy of switching to alternative anti-CD20 agents vs. belimumab in SLE patients with 2NDNR to rituximab. Methods: One hundred and twenty five patients received rituximab and had evaluable data. 77/125 received repeat rituximab cycles. Of these, 14/77 (18%) had 2NDNR. 8/14 patients were switched to belimumab (CD20-to-belimumab group) and 6/14 patients were switched to an alternative humanised anti-CD20 agent (CD20-to-CD20 group, ocrelizumab n = 3, ofatumumab n = 2, obinutuzumab n = 1). Efficacy was assessed using the BILAG-2004, SLEDAI-2K, SRI-4, and daily prednisolone requirement at baseline and 6 months. Results: In the CD20-to-belimumab group, only one patient achieved an SRI-4 and 2/8 patients had new/worsening BILAG-2004 grade A for lupus nephritis. There was no improvement in SLEDAI-2K; median (IQR) was 11.0 (9.5-14.8) at baseline and 10 (9.5-15.5) at 6 months. Median (IQR) prednisolone dose increased from 7.5 mg (4.4-12.5) to 10 mg (6.3-10). In the CD20-to-CD20 group, all 6 patients achieved an SRI-4. Median (IQR) SLEDAI-2K improved from 16.0 (10.3-24.0) at baseline to 5.0 (2.5-6.0) at 6 months. Median (IQR) prednisolone dose decreased from 15 mg (15-15) to 10.5 mg (5.3-15.0). Conclusion: This is the first assessment of belimumab's efficacy in a post-rituximab population. Our data suggests that patients with 2NDNR to rituximab, which constituted 11% of all patients initiated on this drug, should be switched within the same biologic class to another anti-CD20 agent.

Predicting Severe Infection and Effects of Hypogammaglobulinemia During Therapy With Rituximab in Rheumatic and Musculoskeletal Diseases.

OBJECTIVE: To evaluate predictors of serious infection events (SIEs) during rituximab (RTX) therapy and effects of hypogammaglobulinemia on SIE rates, and humoral response and its persistence after discontinuation of RTX in the treatment of rheumatic and musculoskeletal diseases (RMDs). METHODS: A retrospective longitudinal study of 700 RMD patients treated with RTX in a single center was conducted. Immunoglobulin levels were measured at baseline and at 4-6 months after each treatment cycle. Baseline predictors of SIEs were assessed using multivariable logistic regression; for RTX cycles 2-4, a mixed-effects logistic regression model was used. RESULTS: A total of 507 patients (72%) had rheumatoid arthritis, 94 (13%) had systemic lupus erythematosus, 49 (7%) had antineutrophil cytoplasmic antibody-associated vasculitis, and 50 (7%) had other RMDs. The number of SIEs recorded was 281 in 176 patients (9.8 per 100 person-years). Predictors of SIEs included non-RTX-specific comorbidities (previous history of SIE, cancer, chronic lung disease, diabetes mellitus, and heart failure), higher corticosteroid dose, and RTX-specific factors, including low IgG (<6 gm/liter) both at baseline and during treatment, RTX-associated neutropenia, higher IgM, and longer time to RTX re-treatment, but not B cell count or depletion status. Of 110 patients with low IgG, SIE rates were higher in those with low IgG at baseline (16.4 per 100 person-years) and in those who acquired low IgG during or after RTX treatment (21.3 per 100 person-years) versus those with normal IgG (9.7 per 100 person-years). Five of 8 patients (63%) had impaired humoral response to pneumococcus and hemophilus following vaccination challenge, and only 4 of 11 patients (36%) had IgG normalized after switching biologic disease-modifying antirheumatic drugs. CONCLUSION: Immunoglobulin levels should be monitored at baseline and before each RTX cycle to identify patients at risk of SIEs. Individualized risk-benefit assessment should be undertaken in those with lower IgG as this is a consistent SIE predictor and may increase infection profiles when RTX is switched to different therapies.