If a clinical response is seen among study participants following treatment, further analyses will be conducted to explore any differential effects of immunosuppression in participants with early-stage disease and later-stage disease. To ensure adequate numbers of participants for conditional analyses stratifying by symptom onset date, participants will be enrolled based on symptom onset within 24 months of the screening visit or more than 24 months before screening. All participants will have the same treatment and will be treated as a single group for the analyses of the main study outcomes.