Analysis of the Immunogenicity from Abatacept-Treated Pediatric Patients With Polyarticular-Course Juvenile Idiopathic Arthritis: Findings From Two Phase III Clinical Trials.

OBJECTIVE: The goal of this article is to present the analysis of anti-abatacept antibody data from children with polyarticular-course juvenile idiopathic arthritis (pJIA), treated with abatacept. The data are from 395 participants with pJIA from two abatacept registrational trials. METHODS: We analyzed immunogenicity data according to age groups, administration route (intravenous [IV] or subcutaneous [SC]), drug treatment interruption, and co-medications (with or without methotrexate [MTX]) to assess impact on the incidence of anti-abatacept antibodies. RESULTS: The overall immunogenicity incidences observed in both JIA trials ranged between 4.7% and 23.3%. There was a slightly higher immunogenicity incidence in the 2-5-year-old participants (15.2%) compared with 6-17-year-old participants (4.7%). In the study with SC dosing, the overall incidence on treatment was 2.3% (3% if co-dosed with MTX), similar to the incidence for Period A of the IV study (similar duration of treatment as the SC study), which was 2.1% (1.4% if co-dosed with MTX). In the IV study, the period following a 6-month interruption in treatment had comparable immunogenicity incidences (22.9% with interruption vs. 18.2% without interruption, both co-dosed with MTX and 0% for both not co-dosed with MTX). In most cases, participants co-dosed with MTX had higher immunogenicity incidences than those on abatacept alone. CONCLUSION: Although some trends were noted in terms of incidence according to age and MTX co-dosing, none where conclusive owing to differences in population size. Drug holiday had no impact on immunogenicity incidence once treatment was resumed, and incidences across SC and IV dosing were comparable. There was no impact of immunogenicity on pharmacokinetics, safety, and efficacy.

Validation and life-cycle management of a quantitative ligand-binding assay for the measurement of Nulojix(®), a CTLA-4-Fc fusion protein, in renal and liver transplant patients.

BACKGROUND: Nulojix(®) is a fusion protein composed of the Fc portion of a human IgG1 linked to the extracellular modified domain of CTLA-4. Nulojix differs from another Bristol Myers Squibb product, Orencia(®) by two amino acids and was approved by the FDA on 15 June 2011 for the prophylaxis of organ rejection in adult patients receiving kidney transplant. RESULTS: A sandwich ELISA utilizing two monoclonal antibodies against CTLA-4 was employed for Nulojix quantification and pharmacokinetic analysis. At least 17 analysts have qualified on the assay and contributed to reportable results over the last 7 years. In-study accuracy and precision demonstrate suitable performance: %bias within -4 to 4%, %CV ≤13% and total error within 6-15%. Incurred sample reanalysis was completed in applicable disease-state populations. The assay was automated and validated in additional clinical matrices (ascites and urine) and Nulojix quantification was validated in the presence of clinically relevant co-administered compounds. In 2011, the biotinylation procedure was modified meriting a regression change (quadratic to 4-parameter logistic) and associated partial validation. CONCLUSION: This long-term pharmacokinetic program provides a good example of the dynamic clinical environment and adaptation requirements of ligand-binding assays.