 Double-blind Treatment Phase: Maintenance One MPR treatment arm MPRR will continue taking lenalidomide 10 mg in Maintenance. The other MPR treatment arm MPRp will take placebo in Maintenance. The MP p treatment arm will take placebo in Maintenance MPpp. If disease progression, subjects have the option to enter the Open-Label Extension Phase to obtain treatment with lenalidomide, or to enter into the Follow-up Phase. 