Standard chemotherapy was used as a positive validation arm. Randomization was performed so that there could be no bias in the selection of participants for enrollment into the fixed-sequence arms. Once three chemotherapy-treated participants demonstrated decreases in FDG-PET SUV in the target lesion (i.e., >20% decrease in SUVmax in the defined target lesion) in the PET/computed tomography (CT) scan performed following Cycle 1 Period 1 treatment, it was concluded that this positive validation arm had accomplished its purpose, and all subsequent participants enrolled in the study were assigned treatment with robatumumab for Period 1. There was no intention to compare the data in either period across participants who received chemotherapy with those who received robatumumab.