In a randomised open-label phase I/II trial (CheckMate 032), evaluating nivolumab with or without ipilimumab in pretreated SCLC patients with progressive disease and sensitive or refractory to platinum based chemotherapy, based on an interim analysis a response rate of 33% and disease stabilisation in 22% was observed for the combination of nivolumab and ipilimumab compared to 18% response rate and 20% stable disease with nivolumab mono-therapy.