A Pooled Analysis of the HGS1006-C1056 (BLISS-52) and HGS1006-C1057 (BLISS-76) Studies

Efficacy and Safety of Belimumab in a Subgroup of Systemic Lupus Erythematosus (SLE) Patients With Higher Disease Activity (Anti-dsDNA Positive and Low Complement): A Pooled Analysis of the HGS1006-C1056 (BLISS-52) and HGS1006-C1057 (BLISS-76) Studies

Efficacy and Safety of Belimumab in a Subgroup of Systemic Lupus Erythematosus (SLE) Patients with Higher Disease Activity (anti-dsDNA positive and low complement): A Pooled Analysis of the HGS1006-C1056 (BLISS-52) and HGS1006-C1057 (BLISS-76) Studies

Studies C1056 and C1057 followed very similar protocols, were of nearly identical design, had common inclusion and exclusion criteria, and were conducted over the same time period. Nevertheless, given the heterogeneous presentation of SLE disease and the fact that the Phase III program was run globally, variation in the patient population, both within the studies (e.g., between different centres) and between the studies (analogous to differences between centres within the same study) should be expected. Since it has been established that the conduct of the studies was effectively the same, it then must be determined whether the relative treatment effect is different in one study compared with the other study when evaluating whether two studies are similar enough to pool. Each of these Phase III studies achieved statistical significance for belimumab 10 mg/kg on the pre-specified primary endpoint of SRI response at Week 52; therefore, these nearly identical studies provide independent replication of results. While pooling is not necessary to establish the effectiveness of belimumab, it was considered appropriate in order to evaluate treatment effects in the high disease activity subgroup of interest, given that the individual studies were not designed to provide sufficient power to demonstrate effectiveness within subgroups. Thus, statistical evaluation pooling the studies and testing for a treatment-by-study interaction was undertaken. A significant treatment-by-study interaction would indicate that the relative treatment differences were statistically different in the two studies and pooling would not be justified. Conversely, the lack of a treatment-by-study interaction would indicate the studies resulted in a similar treatment response and pooling would be justified. When the two Phase III studies were pooled for the SRI analysis, the treatment-by-study interaction was >0.5. Likewise, for the target population of high disease activity, the treatment-by-study interaction was >0.7 suggesting that the high disease activity subgroup may be more homogenous and therefore have a more similar treatment effect between the studies than the population as a whole. Given these considerations, it is reasonable and valid to pool the two studies and allows better precision for evaluation of subgroups.

Quality of life assessment tools were similar across the treatment groups and indicated that there was impairment in quality of life of subjects in the Low C+anti-dsDNA Population

Belimumab 1 mg/kg IV plus standard therapy; belimumab 1 mg/kg administered on Days 0, 14, 28, and every 28 days thereafter through 72 weeks.

Belimumab 10 mg/kg IV plus standard therapy; belimumab 10 mg/kg administered on Days 0, 14, 28, and every 28 days thereafter through 72 weeks.

Placebo IV plus standard therapy; placebo administered on Days 0, 14, 28, and every 28 days thereafter through 72 weeks.

Composite endpoint resulting from the combination of three well-established tools for evaluating SLE disease activity which include an objective measure of the reduction in global disease activity for efficacy and two measures to ensure that the improvement in disease activity (score) is not offset by worsening of the subject's condition overall.

The response rate by visit modified to exclude anti-dsDNA and complement items in the determination of a 4-point reduction in SELENA SLEDAI (Safety of Oestrogen in Lupus National Assessment Systemic Lupus Erythematosus Disease Activity Index).

The percent of subjects with no new BILAG A (British Isles Lupus Assessment Group) organ domain score or 2 new BILAG B organ domain scores

Percent of subjects with greater than 4 point reduction from baseline in SELENA SLEDAI (Safety of Oestrogen in Lupus National Assessment Systemic Lupus Erythematosus Disease Activity Index)

Number of subjects experiencing a flare/severe flare (Weeks 0-52 and Weeks 24-52). Time to 1st flare/severe flare (Weeks 0-52 and Weeks 24-52.) Flares/Severe flares per subject year (Weeks 0-52).

Number of subjects experiencing a BILAG A flare (Weeks 0-52 and Weeks 24-52). Time to 1st BILAG A flare (Weeks 0-52 and Weeks 24-52). BILAG A flares per subject year (Weeks 0-52).

Percent of Subjects with Daily Prednisone Dose Reduced to ≤ 7.5 mg/day from > 7.5 mg/day at Baseline by Visit

Mean change in SF-36 (Short Form 36 Health Survey questionnaire) domains (population a only), Physical Component Summary (PCS) and Mental Component Summary MCS (population a only)

EQ-5D (EuroQol five dimension self-reported health state questionnaire) individual item score (mobility, self-care, usual activities, pain/discomfort, anxiety/depression)

Improvement in each SELENA SLEDAI (Safety of Oestrogen in Lupus National Assessment Systemic Lupus Erythematosus Disease Activity Index) organ domain

Percent of Subjects with Daily Prednisone Dose Increased to > 7.5 mg/day from ≤7.5 mg/day at Baseline by Visit

Percent of Subjects with Daily Prednisone Dose Reduced by ≥25% and to ≤ 7.5 mg/day from > 7.5 mg/day at Baseline by Visit

Time to first SELENA SLEDAI (Safety of Oestrogen in Lupus National Assessment Systemic Lupus Erythematosus Disease Activity Index) organ improvement by organ domain, among subjects with involvement at baseline

EQ-5D (EuroQol five dimension self-reported health state questionnaire) index score using value set for the UK

EQ-5D (EuroQol five dimension self-reported health state questionnaire) visual analogue scale (VAS) score using value set for the UK

The response rate calculated without allowable and prohibited medication rules applied (population a only).

Inclusion Criteria: Clinical diagnosis of SLE by ACR criteria. Active SLE disease. Autoantibody-positive. On stable SLE treatment regimen. Exclusion Criteria: Pregnant or nursing Have received treatment with any B cell targeted therapy. Have received treatment with a biological investigational agent in the past year. Have received IV cyclophosphamide within 180 days of Day 0. Have severe lupus kidney disease. Have active central nervous system (CNS) lupus. Have required management of acute or chronic infections within the past 60 days. Have current drug or alcohol abuse or dependence. Have a historically positive test or test positive at screening for HIV, hepatitis B, or hepatitis C.

Subjects who were anti-dsDNA positive and had low C3 and/or C4 at baseline (Low C+anti-dsDNA Population) Subjects with baseline SELENA SLEDAI score >= 10 (SS >=10 Population)

van Vollenhoven RF, Petri MA, Cervera R, Roth DA, Ji BN, Kleoudis CS, Zhong ZJ, Freimuth W. Belimumab in the treatment of systemic lupus erythematosus: high disease activity predictors of response. Ann Rheum Dis. 2012 Aug;71(8):1343-9. doi: 10.1136/annrheumdis-2011-200937. Epub 2012 Feb 15.