METHODS: In this phase Ib, randomized, double-blind, placebo-controlled study, patients received AMG 557 210 mg (n = 10) or placebo (n = 10) weekly for 3 weeks, then every other week for 10 additional doses. The corticosteroid dosage was tapered to ≤7.5 mg/day by day 85, and immunosuppressants were discontinued by day 29. Primary end points on day 169 were safety, immunogenicity, the Lupus Arthritis Response Index (LARI; defined by a reduction in the tender and swollen joint counts), ≥1-letter improvement in the musculoskeletal domain of the British Isles Lupus Assessment Group (BILAG) index, and medication discontinuation. The secondary/exploratory end points were changes in the tender and swollen joint counts, BILAG index scores (musculoskeletal, global), and the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI).

RESULTS: The incidence of adverse events, most of which were mild, was similar between groups. LARI responses occurred in 3 of 10 patients receiving AMG 557 and 1 of 10 patients receiving placebo (P = 0.58). More patients in the AMG 557 group achieved a ≥4-point improvement in the SLEDAI score on day 169 (7 of 10 patients) compared with the placebo group (2 of 10 patients) (P = 0.07). Patients treated with AMG 557 (versus placebo) had greater improvements from baseline in the global BILAG index scores (-36.3% versus -24.7%) and the SLEDAI score (-47.8% versus -10.7%) and in tender (-22.8% versus -13.5%) and swollen (-62.1% versus -7.8%) joint counts on day 169.

METHODS: In this phase Ib, randomised, multiple-dose escalation study (NCT00818948), subjects without LN were randomised to subcutaneous AMG 811 (6, 20 or 60 mg) or placebo and subjects with LN were randomised to subcutaneous AMG 811 (20, 60 or 120 mg) or placebo every four weeks for three total doses. Outcomes included incidence of adverse events (AEs); pharmacokinetics; levels of serum proteins (CXCL-10, interleukin 18, monocyte chemotactic protein-1); changes in gene transcript profiles and clinical parameters (Safety of Estrogen in Lupus Erythematosus National Assessment-Systemic Lupus Erythematosus Disease Activity Index (SELENA-SLEDAI) scores, proteinuria, anti-double-stranded DNA (anti-dsDNA) antibodies, C3 complement, C4 complement).

RESULTS: Fifty-six subjects enrolled (28 SLE without LN; 28 with LN). Baseline mean SELENA-SLEDAI scores were 2.2 and 12.0 for SLE subjects without and with LN, respectively. Most subjects reported an AE; no meaningful imbalances were observed between AMG 811 and placebo. Pharmacokinetic profiles were similar and mostly dose-proportional in subjects without or with LN. AMG 811 treatment reduced CXCL-10 protein levels and blood-based RNA IFN-γ Blockade Signature compared with placebo. Reductions were less pronounced and not sustained in subjects with LN, even at the highest dose tested, compared with subjects without LN. No effect on SELENA-SLEDAI scores, proteinuria, C3 or C4 complement levels, or anti-dsDNA antibodies was observed.

CONCLUSION: AMG 811 demonstrated favourable pharmacokinetics and acceptable safety profile but no evidence of clinical impact. IFN-γ-associated biomarkers decreased with AMG 811; effects were less pronounced and not sustained in LN subjects.