This is an open-label, multicenter, randomized, parallel, 2-arm, efficacy and safety study. Patients with GBM after failure of standard first line therapy will be randomized in a 2:1 ratio to receive berubicin or lomustine for the evaluation of OS. Additional endpoints will include response and progression outcomes evaluated by a blinded central reviewer for each patient according to RANO criteria. A pre-planned, non-binding futility analysis will be performed after approximately 30 to 50% of all planned patients have completed the primary endpoint at 6 months. This review will include additional evaluation of safety as well as secondary efficacy endpoints. Enrollment will not be paused during this interim analysis.