OBJECTIVE: This post hoc analysis compared anifrolumab 300 mg every 4 weeks with 
placebo on rash and arthritis measures with different stringency in patients 
with moderate to severe SLE (phase IIb; MUSE; NCT01438489). Subgroups were 
analysed by type I interferon gene signature (IFNGS test-high or test-low).
METHODS: Rash was measured with the SLE Disease Activity Index 2000 (SLEDAI-2K), 
British Isles Lupus Assessment Group (BILAG) Index and modified Cutaneous Lupus 
Erythematosus Disease Area and Severity Index (mCLASI). Arthritis was evaluated 
using SLEDAI-2K, BILAG and swollen and tender joint counts. Outcomes were 
measured at week 52.
RESULTS: More anifrolumab-treated patients demonstrated resolution of rash by 
SLEDAI-2K versus placebo: 39/88 (44.3%) versus 13/88 (14.8%), OR (90% CI) 4.56 
(2.48 to 8.39), p<0.001; improvement of BILAG: 48/82 (58.5%) versus 24/85 
(28.2%), OR (90% CI) 3.59 (2.08 to 6.19), p<0.001; and ≥50% improvement by 
mCLASI: 57/92 (62.0%) versus 30/89 (33.7%), OR (90% CI) 3.31 (1.97 to 5.55), 
p<0.001. More anifrolumab-treated patients had improved arthritis by SLEDAI-2K 
versus placebo: 55/97 (56.7%) versus 42/99 (42.4%), OR (90%  CI) 1.88 (1.16 to 
3.04), p=0.032;  and BILAG: 65/94 (69.1%) versus 47/95 (49.5%), OR (90% CI) 2.47 
(1.48 to 4.12), p=0.003; and mean (SD) swollen and tender joint reductions: -5.5 
(6.3) versus -3.4 (5.9), p=0.004. Comparable results were demonstrated in IFNGS 
test-high patients (n=151). In IFNGS test-low patients (n=50), substantial 
numerical differences in partial rash and arthritis responses were observed in 
anifrolumab-treated patients versus placebo, with statistical significance only 
for rash by BILAG in this small population.
CONCLUSIONS: Anifrolumab treatment was associated with improvements versus 
placebo in specific SLE features of arthritis and rash using measures of 
different stringency. Although driven by robust data in the prevalent IFNGS 
test-high population, further evaluation in IFNGS test-low patients is 
warranted.