Abstract
Keywords
Introduction
Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a rare autoimmune disease that predominantly affects small vessels, leading to endothelial injury and tissue damage. 1 The three primary clinicopathological types of AAV—granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic GPA (EGPA)—share several clinical traits, pathophysiological origins, and treatment approaches. 2 AAV affects an average of 0.4–24 individuals per million annually. 3 GPA’s incidence and prevalence rates are 9.7 and 62.9 per million individuals in the United Kingdom, respectively, compared to 13 and 218 per million individuals in the United States of America.4,5 It has been estimated that there are 9–94 MPA cases per million individuals worldwide. MPA is more common in Southern Europe and Asia, while GPA is more common in Northern Europe. Their incidence increases with age, reaching a high level in the 60–70-year-old age group.6,7
Immunosuppressive drugs are used to induce remission and for long-term maintenance therapy. Cyclophosphamide or rituximab with glucocorticoids is recommended as induction therapy for severe life-threatening AAV. Plasmapheresis may be added for severe diffuse pulmonary hemorrhage or rapidly progressing renal failure. 5 Recommendations for maintenance therapy include tapering glucocorticoids, rituximab, azathioprine, or methotrexate. 8 Rituximab is a chimeric monoclonal anti-membrane spanning 4-domains A1 (MS4A1/CD20) immunoglobulin G subclass 1 (IgG1) antibody that binds to the transmembrane protein CD20 with high specificity. 9 Most patients involved in landmark randomized clinical trials that assessed rituximab as a remission induction and maintenance medication were Caucasian; only small percentages of the included patients were of Hispanic or African ancestry. 1 In addition, several non-randomized observational studies have provided further details regarding the effectiveness and safety of rituximab. 10 The use of rituximab depends on its availability and cost. 11 In this study, we evaluated the results of patients with AAV treated with rituximab at a single tertiary center.
Materials and methods
Clinical and laboratory data were retrospectively collected from patients with AAV who visited the Louise Coote Lupus unit. We describe the clinical features and laboratory results of patients with AAV following rituximab treatment, including their ability to reduce corticosteroid dosage to <7.5 mg daily, B cell depletion, and outcomes. The inclusion criteria were adult patients with AAV who were treated with rituximab and received either 1 g every 6 months for the following 2 years or at least two standard doses, one standard course with a total of three doses, or one standard course of three doses with another dose repeated in 6 months. The exclusion criteria were patients with AAV who did not receive rituximab. This study adhered to the Declaration of Helsinki and was approved by the Research and Development Office of Guy and St. Thomas’ Hospital (approval number: No-13492). Written consent was not required since this was a retrospective study using anonymized data.
Statistical analysis
The statistical analysis was performed using the IBM SPSS software (version 25.0). Numeric response variables were collected and described as median and range, including disease duration, age, follow-up duration, and Birmingham Vasculitis Activity Score BVAS version 3. 12 Categorical variables are presented as frequencies and percentages, including sex, ethnicity, clinical manifestation, type of ANCA autoantibodies, laboratory features, B cell depletion, ability to reduce corticosteroid dosage, immunosuppression therapy used, and patient outcomes (remission vs active disease) following rituximab use. The chi-square test was used to compare categorical variables between patient outcomes. The level of statistical significance was defined as a p < .05.
Results
Patients’ characteristics and AAV outcome.
AAV: antineutrophil cytoplasmic antibody-associated vasculitis; GPA: granulomatosis with polyangiitis; EGPA: eosinophilic granulomatosis with polyangiitis; MPA: microscopic polyangiitis; PR3: anti-proteinase-3; MPO: (please define this); UPCR: urine protein-creatinine ratio; ESR: erythrocyte sedimentation rate; CRP: C Reactive protein; BVAS: Birmingham Vasculitis Activity Score.
Association between study variables and disease outcome.
**p<.01, *p<.05. ANCA: antineutrophil cytoplasmic antibody; AAV: antineutrophil cytoplasmic antibody-associated vasculitis; GPA: granulomatosis with polyangiitis; EGPA: eosinophilic granulomatosis with polyangiitis; MPA: microscopic polyangiitis; ENT: ear, nose, and throat.
Type of immunosuppression in induction and maintenance.
MMF: mycophenolatemofetil; AZA: azathioprine; MTX: methotrexate; HCQ: hydroxychloroquine.
Discussion
This study evaluated the outcomes of 50 patients with AAV treated with rituximab as a remission induction or maintenance therapy based on real-world experience. Our findings showed that most patients experienced clinical remission after rituximab maintenance treatment. Despite being of various ethnicities, most of our patients were Caucasian (78.8%). Only one patient was of African ancestry, limiting the generalizability of these data.
The disease duration in our study group ranged from one to 10 years, and there were equal numbers of male and female patients. 13 Unlike the male predominance in Western cohorts, our data are consistent with other studies.14,15 Clinical signs and symptoms of AAV typically impact several body areas. 16 Depending on their disease severity and prognostic factors, patients with AAV frequently have poor prognoses. 17 This prognosis is attributable to the high rate of the disease’s relapse and its associated complications, either due to the disease or its complications or the adverse side effects of treatment. The long-term exposure to glucocorticoids caused by AAV’s relapsing/remitting nature is frequently associated with serious adverse effects and considerable morbidity. 18 Similar to other autoimmune disorders, attempts are being made to create alternative therapies that require lower levels of glucocorticoid use. 19 Most previous clinical trials and retrospective studies have examined the relationship between high dosages of glucocorticoids and rituximab as remission induction therapy for AAV.20–23 In our study, we used two standard rituximab doses of 1 g, followed by multiple doses (median = 2 [1–9]), along with different combinations of immunosuppressants, achieving remission in 39 patients. Low-dose rituximab has shown similar results as conventional doses in other autoimmune diseases. 24 Takakuwa et al. 25 reported similar cumulative complete remission in patients treated with low-dose and high-dose rituximab.26–28
The most diagnosed type of AAV was GPA, with 30 patients (75%) in remission and 10 (25%) with active disease. In our study, GPA was relatively more common than EGPA or MPA (Table 1). The most frequently reported involvement in this study was pulmonary, particularly lower respiratory involvement. Other studies have reported similar results.29,30
Pulmonary manifestations were common in our cohort of patients with GPA and MPA, similar to previous studies.29,30 Due to the high percentage of patients with lower lung involvement (77.8%), various complications were identified, with infection (10%) being the most common. While pulmonary manifestations were slightly more common in our patients with GPA, more serious respiratory conditions were present in our patients with MPA. A recent review of patients with AAV living in Chicago also concluded that Hispanic patients with AAV present more severe disease activity. However, GPA is the predominant subtype of this disease. 31
Unlike in Holle et al., 23 the presence of granulomatous lesions was not associated with poor response to rituximab treatment in our study. This finding can likely be attributed to the high frequency of pulmonary masses in our patients since such patients generally respond better to treatment than those with other granulomatous manifestations. 23 However, low response rates have been associated with subglottic stenosis.23,32,33 In our cohort, the median BVAS was 9 (4–26) at baseline and 0 (0–15) at the latest follow-up. Relapse rates were higher in patients whose pre-to post-rituximab BVAS scores decreased from 9 to 0, consistent with Yoo et al., 31 who reported that patients with high and low BVAS ratings experienced higher relapse rates. Nevertheless, the limitations of this study included its retrospective design and small sample size due to the disease’s rarity, which impacted the statistical significance of some correlations. In addition, several data were missing or incomplete in the patient records due to its retrospective collection.
Conclusions
Our data show that most patients experienced clinical remission following rituximab maintenance treatment. Half the patients were in remission, with normal creatinine levels and inflammatory markers. In addition, our patients were able to reduce steroid use. This single-center real-world data corroborates the extensive clinical trial data regarding AAV outcomes after rituximab therapy.
Study limitations
This retrospective study had a limited sample size due to the rarity of the disease and the possibility of missing or incomplete patient records.
Footnotes
Author contributions
Conceptualization: FA, SS, and DDC; data curation: FA, SS, and DDC; formal analysis and methodology: FA; supervision: SS and DDC; writing—original draft: FA; writing—review and editing: SS and DDC. All authors have read and approved the published version of the manuscript.
Declaration of conflicting interests
The authors declare no conflicts of interest regarding the research authorship and/or publication of this article.
Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The authors extend their appreciation to to the Deputyship for Research & Innovation, Ministry of Education in Saudi Arabia, for funding this research (project number: RI-44-0018).
