A Study of LY3471851 in Adults With Systemic Lupus Erythematosus (SLE)

Percentage of Participants Who Achieved British Isles Lupus Assessment Group (BILAG) Based Composite Lupus Assessment (BICLA) Response at Week 24.

Percentage of Participants who Achieve BICLA Response at Week 24. The BILAG-based Composite Lupus Assessment (BICLA) is a composite index used to assess disease activity in SLE. A BICLA response is defined as: * Reduction of all baseline BILAG-2004 A to B or C or D; and baseline BILAG-2004 B to C or D; and no BILAG-2004 worsening in other organ systems, as defined by ≥1 new BILAG-2004 A or ≥2 new BILAG-2004 B. * No worsening from baseline in SLEDAI-2K, where worsening is defined as any increase from baseline in SLEDAI-2K. * No worsening from baseline in participants' lupus disease activity, where worsening is defined by an increase ≥0.30 points on a 3-point PGA visual analogue scale (VAS).

Time frame: Week 24

Percentage of Participants Who Achieved Systemic Lupus Erythematosus Responder Index 4 (SRI-4) Response at Week 24

Percentage of Participants who Achieved a SRI-4 Response at Week 24. A SRI-4 response is defined as a decrease in SLEDAI-2K \>= 4 from baseline. No new BILAG A and no more than 1 new BILAG B disease activity score / organ domain (both compared with baseline), and no worsening in PGA (defined as an increase of 0.3 points \[10 mm\] from baseline.

Time frame: Week 24

Percentage of Participants Who Achieved Lupus Low Disease Activity State (LLDAS) at Week 24

Percentage of Participants who Achieved LLDAS at Week 24. A LLDAS response is defined as a low level of disease activity attained without use of low-dose steroids and/or standard-of-care immunosuppressant medications.