This is a Phase III, multicenter, multinational, operationally seamless 2-stage study. The study will be conducted in 2 stages: Stage 1 and Stage 2. Participants will take part in either Stage 1 or Stage 2.Each stage has a randomized, 24-week double-blind, placebo controlled study period (Week 0 to Week 23), to evaluate the efficacy and safety of a SC treatment regimen of anifrolumab (120 mg, once weekly dosing) in adult participants with chronic and/or subacute CLE. The primary endpoint will be assessed at Week 24. The doubleblind, placebo-controlled study period of 24 weeks will be followed by an open-label, uncontrolled treatment period in which all participants will receive SC treatment with anifrolumab (120 mg, once weekly) from Week 24 to Week 51. After the open label treatment period, participants will enter a 12-week Safety Follow-up Period. The study will be performed in approximately 460 adult participants aged 18 to 70 years (inclusive). Stage 1 of the study is planned to be performed in approximately 100 participants (n ~ 50 per treatment arm). Stage 2 of the study is planned to be performed in approximately 360 participants (n ~ 180 per treatment arm).