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Objectives: Mycophenolic acid (MPA) is the active form of mycophenolate mofetil (MMF), which is currently used off-label as immunosuppressive therapy in childhood-onset SLE (cSLE). The objectives of this study were to (1) characterize the pharmacokinetics (MPA-PK) and pharmacodynamics (MPA-PD) of MPA and (2) explore the relationship between MPA-PK and cSLE disease activity., Methods: MPA-PK [area under the curve from 0-12 hours (AUC(0-12))] and MPA-PD [inosine-monophosphate dehydrogenase (IMPDH) activity] were evaluated in cSLE patients on stable MMF dosing. Change in SLE disease activity while on MMF therapy was measured using the British Isles Lupus Assessment Group (BILAG) index., Results: A total of 19 AUC(0-12) and 10 IMPDH activity profiles were included in the analysis. Large interpatient variability in MPA exposure (AUC(0-12)) was observed (mean ± SE: 32 ± 4.2 mg h/L; coefficient of variation: 57%). Maximum MPA serum concentrations coincided with maximum IMPDH inhibition. AUC(0-12) and weight-adjusted MMF dosing were only moderately correlated (r = 0.56, P = 0.01). An AUC(0-12) of ≥30 mg h/L was associated with decreased BILAG scores while on MMF therapy (P = 0.002)., Conclusion: Weight-adjusted MMF dosing alone does not reliably allow for the prediction of exposure to biologically active MPA in cSLE. Individualized dosing considering MPA-PK appears warranted as this allows for better estimation of immunologic suppression (IMPDH activity). Additional controlled studies are necessary to confirm that an MPA AUC(0-12) of at least 30 mg h/L is required for cSLE improvement., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Objective: To prospectively validate the provisional criteria for the evaluation of response to therapy in children with systemic lupus erythematosus (SLE)., Methods: In this multicenter study, childhood-onset SLE patients (n = 98; 81 girls, 17 boys, 50% white, 88% non-Hispanic) were followed every 3 months for up to 7 visits (total number of visits 623). The 5 childhood-onset SLE core response variables were obtained at the time of each visit: 1) physician assessment of overall disease activity, 2) parent assessment of patient well-being, 3) Child Health Questionnaire, 4) proteinuria, and 5) global disease activity measure score, as measured by the European Consensus Lupus Activity Measure (ECLAM), the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), or the Systemic Lupus Activity Measure (SLAM). Physician-rated relevant changes in the disease course (clinically relevant improvement, no change in disease, or worsening) between visits served as the criterion standard. Mixed models were used to assess the diagnostic accuracy of the 4 highest-ranked provisional definitions of response to therapy., Results: There were 89 episodes of clinically relevant improvement between 2 consecutive visits, and 448 episodes without improvement. Irrespective of the choice of the global disease activity measure (ECLAM, SLAM, SLEDAI), sensitivities of all 4 highest-ranked definitions were low (all < or =31%), whereas their specificities were excellent (all >88%). Using logistic models, alternative definitions can be developed with both 80% sensitivity and specificity., Conclusion: The provisional criteria of response to therapy in childhood-onset SLE may have considerably lower sensitivity than previously reported. Additional validation in clinical trials is necessary to further evaluate the measurement properties of the provisional Paediatric Rheumatology International Trials Organisation/American College of Rheumatology criteria for response to therapy in children with SLE.

Objective: To (1) estimate the health-related quality of life (HRQOL) of children with childhood-onset systemic lupus erythematosus (cSLE) and compare it to that of normative cohorts; (2) assess the relationship of HRQOL with cSLE disease activity and damage; and (3) determine the effects of changes of disease activity on HRQOL., Methods: Patients with cSLE (n = 98) followed every 3 months completed HRQOL measures, the Pediatric Quality of Life Inventory Generic Core scale (PedsQL-GC), the Rheumatology Module (PedsQL-RM), and the Child Health Questionnaire (CHQ). The British Isles Lupus Activity Group Index (BILAG) was used to measure organ-system-specific disease activity. Physicians rated the course of cSLE between visits., Results: At baseline, mean (standard deviation, SD) score [parent report] of the PedsQL-GC and the PedsQL-RM was 75 (17) and 79 (14), respectively; the mean (SD) of the CHQ physical summary score (CHQ-PHS) was 49 (7) and that of the CHQ psychological summary score was 42 (12). Higher BILAG scores, especially in the general, musculoskeletal, neurological, and vascular, but not the mucocutaneous, renal, cardiovascular, or hematological BILAG domains, were associated with a significantly lower HRQOL. Patients with damage had lower HRQOL than those without damage. All HRQOL measures included were at most modestly responsive to clinically important changes with cSLE., Conclusion: HRQOL with cSLE is significantly lower than that reported in healthy populations. Organ-specific involvement with cSLE has a differential effect on HRQOL. Higher disease activity and damage are associated with significantly lower HRQOL as measured by the PedsQL-RM and the CHQ-PHS, and worsening of cSLE leads to a further decline.

Lupus nephritis (LN) is among the main determinants of poor prognosis in systemic lupus erythematosus (SLE). The objective of this study was to 1) isolate and identify proteins contained in the LN urinary protein signature (PS) of children with SLE; 2) assess the usefulness of the PS proteins for detecting activity of LN over time. Using surface-enhanced or matrix-assisted laser desorption/ionization time of flight mass spectrometry, the proteins contained in the LN urinary PS were identified. They were transferrin (Tf), ceruloplasmin (Cp), alpha1-acid-glycoprotein (AGP), lipocalin-type prostaglandin-D synthetase (L-PGDS), albumin, and albumin-related fragments. Serial plasma and urine samples were analyzed using immunonephelometry or ELISA in 98 children with SLE (78% African American) and 30 controls with juvenile idiopathic arthritis. All urinary PS proteins were significantly higher with active vs. inactive LN or in patients without LN (all p < 0.005), and their combined area under the receiver operating characteristic curve was 0.85. As early as 3 mo before a clinical diagnosis of worsening LN, significant increases of urinary Tf, AGP (both p < 0.0001), and L-PGDS (p < 0.01) occurred, indicating that these PS proteins are biomarkers of LN activity and may help anticipate the future course of LN.