LONG-TERM OUTCOMES OF PATIENTS WITH PEDIATRIC SYSTEMIC LUPUS ERYTHEMATOSUS (PSLE) TREATED WITH COMBINATION RITUXIMAB AND CYCLOPHOSPHAMIDE: A SINGLE-CENTER COHORT AND REVIEW OF LITERATURE

PV157 / #280 Poster Topic: AS18 - Pediatric SLE Background/Purpose Patients with pSLE with life/organ-threatening manifestations are treated with a protocol of rituximab and cyclophosphamide at our institution as previously described.[1] However, the few published reports of the systematic administration of rituximab and cyclophosphamide in pSLE lacked representation of Black patients and/or evaluation of long-term damage indices beyond 1-2 years. We aimed to evaluate long-term Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) scores, exposure to steroids, and Systemic Lupus International Collaborating Clinics/American College of Rheumatology (SLICC/ACR) Damage Indices of patients with pSLE treated with a systematic administration of rituximab and cyclophosphamide. Methods Retrospective review of medical records between 2013-2023 of patients diagnosed with severe SLE at ≤ 18 years old and treated with rituximab and cyclophosphamide for life/organ-threatening manifestations with at least 1 year of follow-up were found (Table 1). Case records were analyzed for clinical symptoms, physical exam findings, and laboratory and imaging results associated with SLE. Descriptive statistics were calculated with continuous variables as means and categorical variables as percentages. A PubMed search for articles published after 2000 was performed using search terms “cyclophosphamide and rituximab” AND “systemic lupus erythematosus” AND “pediatric patients OR children OR adolescents” to compare prior studies with our cohort. Table 1. Results Eleven patients met eligibility criteria. Nine of the 11 patients completed 60 months of follow-up. The most common symptoms and clinical manifestations of disease included anemia in 8 patients (73% of cohort), mucocutaneous findings of malar or discoid rash as seen in 7 patients (64% of cohort), and proteinuria and renal disease ultimately diagnosed as Class III-V lupus nephritis in 8 patients (73% of cohort) prior to initiation of the Rituximab and Cyclophosphamide protocol. The most severe manifestations included altered mental status due to lupus cerebritis, wet gangrene of the lower extremity requiring trans-metatarsal amputation, and lupus pneumonitis leading to ARDS and multisystem organ failure requiring ECMO. Mean prednisone dose and mean SLEDAI scores decreased significantly over follow-up periods, and we achieved low disease activity in all our patients as defined by SLEDAI score < 4 and prednisone dose < 7.5 mg/day in all our patients (Figure 1). There was no statistically significant difference between SLICC/ACR damage indices over time. No difference in outcomes between races was seen. Our literature review resulted in 7 studies, which varied from case reports (n = 1) to small cohorts (n = 17). We compared our results to those seen in the studies whose population included more than 10 patients (Table 1). Our cohort had a more diverse population, including multiple Black patients, compared to previous studies[1] and included longer-term mean outcomes than earlier studies (51 months vs 10 months, respectively).[2] Despite some variability in dosing, all studies reported improvement of disease activity and relatively low incidence of infections. Conclusions Our racially diverse cohort shows the efficacy of systematic administration of rituximab and cyclophosphamide in decreasing disease activity scores and decreasing overall exposure to steroids in pSLE. Long-term organ damage was not seen 5 years after treatment in our cohort, further emphasizing disease control with early aggressive therapy. This protocol was well tolerated. Larger, prospective randomized clinical trials are needed for further validation. References: [1.] Lehman TJ. Pediatr Rheumatol Online J 2014;12:3. [2.] Ale’ed A. Rheumatol Int 2014; 34:529-33.

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