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Background. Sequential B cell targeted immunotherapy with BAFF antagonism (belimumab) and B cell depletion (rituximab) and may enhance B cell targeting in ANCA-associated vasculitis (AAV) through several mechanisms. Study Design. COMBIVAS is a randomised, double blind, placebo-controlled trial designed to assess the mechanistic effects of sequential therapy of belimumab and rituximab in patients with active PR3-AAV. The recruitment target is 30 patients who meet the criteria for inclusion in the per protocol analysis. Thirty-six participants have been randomised to one of two treatment groups in a 1:1 ratio; either rituximab plus belimumab or rituximab plus placebo (both groups with the same tapering corticosteroid regimen) and recruitment is now closed (final patient enrolled March 2021). For each patient, the trial will last for two years comprising a 12-month treatment period followed by a 12-month follow-up period. Participants. Participants have been recruited from five of seven UK trial sites. Eligibility criteria were age ³18 years, a diagnosis of AAV with active disease (newly diagnosed or relapsing disease), along with a concurrent positive test for PR3-ANCA by ELISA. Interventions. Rituximab 1000mg was administered by intravenous infusions on Day 8 and Day 22. Weekly subcutaneous injections of 200mg belimumab or placebo were initiated a week before rituximab on Day 1 and then weekly through to Week 51. All participants received a relatively low prednisolone (20 mg/day) starting dose from Day 1 followed by a protocol-specified corticosteroid taper aiming for complete cessation by 3 months. Outcomes. The primary endpoint of this study is time to PR3 ANCA negativity. Key secondary outcomes include change from baseline in naïve, transitional, memory, plasmablast B cell subsets (by flow cytometry) in blood at Months 3, 12, 18 and 24, time to clinical remission, time to relapse, and incidence of serious adverse events. Exploratory biomarker assessments include assessment of B cell receptor clonality, B cell and T cell functional assays, whole blood transcriptomic analysis and urinary lymphocyte and proteomic analysis. Inguinal lymph node and nasal mucosal biopsies have been performed on a subgroup of patients at baseline and Month 3. Discussion. This experimental medicine study provides a unique opportunity to gain detailed insights into the immunological mechanisms of belimumab-rituximab sequential therapy across multiple body compartments in the setting of AAV. Trial status. The final patient was recruited in March 2021. Last subject last visit will be March 2023. ClinicalTrials.gov Identifier: NCT03967925, May 30, 2019.

ObjectiveFollowing induction of remission with rituximab in anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) relapse rates are high, especially in patients with history of relapse. Relapses are associated with increased exposure to immunosuppressive medications, the accrual of damage and increased morbidity and mortality. The RITAZAREM trial compared the efficacy of repeat-dose rituximab to daily oral azathioprine for prevention of relapse in patients with relapsing AAV in whom remission was reinduced with rituximab.MethodsRITAZAREM was an international randomised controlled, open-label, superiority trial that recruited 188 patients at the time of an AAV relapse from 29 centres in seven countries between April 2013 and November 2016. All patients received rituximab and glucocorticoids to reinduce remission. Patients achieving remission by 4 months were randomised to receive rituximab intravenously (1000 mg every 4 months, through month 20) (85 patients) or azathioprine (2 mg/kg/day, tapered after month 24) (85 patients) and followed for a minimum of 36 months. The primary outcome was time to disease relapse (either major or minor relapse).ResultsRituximab was superior to azathioprine in preventing relapse: HR 0.41; 95% CI 0.27 to 0.61, pConclusionsFollowing induction of remission with rituximab, fixed-interval, repeat-dose rituximab was superior to azathioprine for preventing disease relapse in patients with AAV with a prior history of relapse.Trial registration numberNCT01697267; ClinicalTrials.gov identifier

ObjectivesEvaluation of rituximab and glucocorticoids as therapy to induce remission after relapse in ANCA-associated vasculitis (AAV) in a prospective observational cohort of patients enrolled into the induction phase of the RITAZAREM trial.MethodsPatients relapsing with granulomatosis with polyangiitis or microscopic polyangiitis were prospectively enrolled and received remission-induction therapy with rituximab (4×375 mg/m2) and a higher or lower dose glucocorticoid regimen, depending on physician choice: reducing from either 1 mg/kg/day or 0.5 mg/kg/day to 10 mg/day by 4 months. Patients in this cohort achieving remission were subsequently randomised to receive one of two regimens to prevent relapse.Results188 patients were studied: 95/188 (51%) men, median age 59 years (range 19–89), prior disease duration 5.0 years (range 0.4–34.5). 149/188 (79%) had previously received cyclophosphamide and 67/188 (36%) rituximab. 119/188 (63%) of relapses had at least one major disease activity item, and 54/188 (29%) received the higher dose glucocorticoid regimen. 171/188 (90%) patients achieved remission by 4 months. Only six patients (3.2% of the study population) did not achieve disease control at month 4. Four patients died in the induction phase due to pneumonia (2), cerebrovascular accident (1), and active vasculitis (1). 41 severe adverse events occurred in 27 patients, including 13 severe infections.ConclusionsThis large prospective cohort of patients with relapsing AAV treated with rituximab in conjunction with glucocorticoids demonstrated a high level of efficacy for the reinduction of remission in patients with AAV who have relapsed, with a similar safety profile to previous studies.

It has been generally believed that human CD8+ memory cells are principally found within the CD45ROhigh population. There are high frequencies of CD8+ memory CTL specific for the human CMV tegument phosphoprotein pp65 in PBMC of long-term virus carriers; the large population of memory CTL specific for a given pp65 peptide contains individual CTL clones that have greatly expanded. In this study, we found high frequencies of pp65 peptide-specific memory CTL precursors in the CD45ROhighCD45RA− population, but also appreciable frequencies in the CD45RAhigh subpopulation. Because the majority of CD8+ T cells in PBMC are CD45RAhigh, more of the total pp65-specific memory CTL pool is within the CD45RAhigh than in the CD45ROhigh compartment. Using clonotypic oligonucleotide probes to quantify the size of individual pp65-specific CTL clones in vivo, we found the CD45RAhigh population contributed 6- to 10-fold more than the CD45ROhigh population to the total virus-specific clone size in CD8+ cells. During primary CMV infection, an individual virus-specific CTL clone was initially CD45ROhigh, but after resolution of infection this clone was detected in both the CD45ROhigh and the CD45RAhigh populations. We conclude that CD45RA+ human CD8+ T cells do not solely comprise naive cells, but contain a very significant proportion of memory cells, which can revert from the CD45ROhigh to CD45RAhigh phenotype in vivo.

At birth, almost all human peripheral blood CD8+ T cells express the costimulatory molecule CD28. With increasing age, the proportion of CD8+ T cells that lack CD28 increases. Because the Ag specificity of CD28−CD8+ T cells has not previously been defined, we studied the contribution of CD28−CD8+ T cells to the memory CD8+ CTL response against two human persistent viruses, human CMV (HCMV) and HIV. From PBMC of healthy virus carriers we generated multiple independent CTL clones specific for defined viral peptides and sequenced their TCR β-chains. We designed clonotypic oligonucleotides complementary to each β-chain hypervariable sequence and quantified the size of individual immunodominant CTL clones in PBMC. Some individual CTL clones were very large, comprising up to 3.1% of all CD8+ T cells in PBMC, and were generally maintained at a stable level for months. Individual virus-specific CTL clones were consistently more abundant in purified CD28− cells than in the CD8+ population as a whole. Because CD28−CD8+ cells as a population have been reported to proliferate poorly in response to mitogen, we studied the function of these virus-specific CD28− CTL clones by quantifying the frequency of peptide-specific CTL precursors using limiting dilution analysis. CD28−CD8+ T cells contained high frequencies of functional memory CTL precursors specific for peptides of HCMV or HIV, generally higher than in the CD8+ T cell population as a whole. We conclude that in asymptomatic HCMV and HIV infection, human CD28−CD8+ T cells contain high frequencies of functional virus-specific memory CTL clones.