 Phase 2 portion of the study. The safest, maximally tolerated dose established as established in Phase 1 for Phase 2 is as follows -- Carfilzomib will be provided at 2036 mgm2 with Irinotecan dosed at 125 mgm2. The purpose of the Phase 2 portion of the study is to assess 6 month survival of relapsed small cell lung cancer ins subjects treated with this combination therapy. 