Trial Outcomes & Findings for Pediatric Lupus Trial of Belimumab Plus Background Standard Therapy (NCT NCT01649765)

The study consisted of three parts (Parts A, B, and C). Part A was a parallel-group study where participants could receive either belimumab or placebo. Participants who completed 48 weeks of treatment and Week 52 assessments in Part A could continue to the open label extension phase (Part B) to receive belimumab. Participants who discontinued study intervention in Part A or Part B could enter the long-term safety follow-up phase (Part C).

A total of 93 participants were enrolled in the study. Data for Part A of the study was disclosed in 2018. This submission includes adverse event data for Parts B and C. Per protocol, long-term follow-up in Parts B and C could conclude earlier than planned once pre-defined criteria were met. 9 participants from Part B were in the study when these criteria were met.

Pediatric Lupus Trial of Belimumab Plus Background Standard Therapy

SRI response is defined as \>=4 point reduction, from Baseline in safety of estrogen in lupus national assessment (SELENA) systemic lupus erythematosus disease activity index (SLEDAI) score, no worsening (increase of \<0.30 points from Baseline) in physician's global assessment (PGA) and no new British Isles Lupus Assessment Group of SLE clinics (BILAG) A organ domain score or 2 new BILAG B organ domain scores compared with Baseline. Analysis was performed using a logistic regression model for the comparison between belimumab and placebo with covariates treatment group, Baseline SELENA SLEDAI score (\<=12 vs. \>=13). Percentage of participants with SRI response at Week 52 of Part A were reported. Intent-to-Treat Population comprised of all participants who were randomized and treated with at least one dose of study agent in Part A. One participant had missing data at Baseline and therefore, could not be included in the analysis.

Percentage of participants meeting PRINTO/ACR Juvenile SLE Response Evaluation criteria for improvement in juvenile SLE using two different PRINTO/ACR Juvenile SLE Response Evaluation definitions of improvement that is Definition 1: At least 50% improvement in any 2 of 5 endpoints below and no more than 1 of the remaining worsening by more than 30% and Definition 2: At least 30% improvement in 3 of 5 endpoints below and no more than 1 of the remaining worsening more than 30%. Endpoints were: 1. Percent change in Parent's Global Assessment (ParentGA) at Week 52, 2. Percent change in PGA at Week 52, 3. Percent change in SELENA SLEDAI score at Week 52, 4. Percent change in Pediatric Quality of Life Inventory (PedsQL) physical functioning domain at Week 52, 5. Percent change in 24 hour proteinuria at Week 52 (gram/24hour equivalent by spot urine protein to creatinine ratio).

ParentGA assesses the participant's overall well-being at the moment rated on a 21-numbered circle visual analog scale (VAS; 0 - very well, 10 - very poorly). Baseline was defined as measurements at Day 0. Percent change from Baseline was calculated by subtracting the Baseline value from value at Week 52 divided by the Baseline value X 100. Last Observation Carried Forward (LOCF) was used. Eight participants had a score of zero at Baseline and therefore, could not be included in the analysis.

The PGA is a 10 centimeter (cm) visual analogue scale (VAS), anchored at 0 (none) and 3 (severe), designed for the physician to indicate the participant's overall disease activity at a particular visit as part of the validated SELENA SLEDAI index. Primary investigator or a subinvestigator scored the PGA for the participant, and same person evaluated the participant each time. Baseline was defined as measurements at Day 0. Percent change from Baseline was calculated by subtracting the Baseline value from value at Week 52 divided by the Baseline value X 100. LOCF was used.

The SELENA SLEDAI score is a weighted index for assessing SLE disease activity in which signs and symptoms, laboratory tests and physician's assessment for each of 9 organ system were given a weighted score and summed if present at the time of the visit or in the preceding 10 days. A SELENA SLEDAI score of 0 would suggest no lupus activity; while a score of 105 is the maximum calculable if all items were scored as being present from active lupus. A decrease of 4 points or more equates to a clinically meaningful improvement. Baseline was defined as measurements at Day 0. Percent change from Baseline was calculated by subtracting the Baseline value from value at Week 52 divided by the Baseline value X 100. One participant had missing data at Baseline and therefore, could not be included in the analysis.

The PedsQL is a generic quality of life scale validated for the pediatric population which consists of 23 items, encompassing 4 health domains: Physical Functioning (8 items), Emotional Functioning (5 items), Social Functioning (5 items), and School Functioning (5 items). From the raw scores of the 23 items, a total summary score and individual domain scores can be calculated. The total and domain scores are each transformed on a 0 to 100 score with higher scores indicating higher quality of life. For Physical Functioning Domain scale, score was from 0 to 100 where, 0 indicates lower quality of life and 100 indicates greater quality of life. Baseline was defined as measurements at Day 0. Percent change from Baseline was calculated by subtracting the Baseline value from value at Week 52 divided by the Baseline Value X 100. LOCF was used.

Percent change from Baseline in proteinuria was calculated. The percent change from baseline to Week 52 in 24 hour proteinuria was analyzed using summary statistics and 95% confidence intervals, without any adjustment for covariates. Baseline was defined as measurements at Day 0. Percent change from Baseline was calculated by subtracting the Baseline value from value at Week 52 divided by the Baseline Value X 100. LOCF was used.

Sustained SRI response was defined as having a response on the primary efficacy endpoint at Weeks 44, 48, and 52. Data for percentage of participants with a sustained SRI response was presented. Drop Outs and Treatment Failures were considered Non-Responders. Only those participants with data available at specific time point were analyzed.

Sustained ParentGA response was defined as having \>0.7 improvement at Weeks 44, 48, and 52 compared at Baseline. Data for percentage of participants with a sustained ParentGA response was presented. Thirteen participants had a score of \<=0.7 at Baseline and therefore, could not be included in the analysis.

An AE is any untoward medical occurrence in a clinical investigation participant, temporarily associated with the use of a medicinal product, whether or not considered related to the medicinal product. Any untoward event resulting in death, life threatening, requires hospitalization or prolongation of existing hospitalization, results in disability/incapacity, congenital anomaly/birth defect, any other situation according to medical or scientific judgment or all events of possible drug-induced liver injury with hyperbilirubinemia were categorized as SAE. Number of participants with AEs and SAEs have been reported.

The pharmacokinetic (PK) population comprised all participants included in the As- Treated population for whom at least one post belimumab treatment PK sample was obtained and analyzed. The PK model was fitted to the observed serum concentration-time data. The maximum (Cmax) and minimum (Cmin) concentrations reported in this table are model derived values at ss, assuming a 10 mg/kg dose administered once every 28 days.

The PK model was fitted to the observed serum concentration-time data. The AUC values reported in this table are model derived values at ss, assuming a 10 mg/kg dose administered once every 28 days.