Phase I trial of verubulin (MPC-6827) plus carboplatin in patients with relapsed glioblastoma multiforme

Verubulin (MPC-6827) is a microtubule-destabilizing agent that achieves high concentrations in the brain. Verubulin disrupts newly formed blood vessels in xenografts. We determined the safety and tolerability of verubulin administered in combination with carboplatin in patients with relapsed glioblastoma multiforme (GBM). Three pre-selected doses of verubulin were tested: 2.1, 2.7, and 3.3 mg/m² in a standard “3+3” design. Verubulin was given every second week of a 6-week cycle in the 2.1 mg/m² cohort or weekly for 3 weeks of a 4-week cycle in subsequent cohorts. Carboplatin was administered intravenously at an area under the curve (AUC) dosage 4 every 2 weeks for the 2.1 mg/m² cohort or on day 1 of each 4-week cycle in subsequent cohorts. Nineteen patients with GBM in first or second relapse were enrolled. Four patients (21 %) experienced a grade 3 or greater verubulin- or carboplatin-related adverse event, including hypesthesia, cerebral ischemia, anemia, and thrombocytopenia. The mean plasma half life of verubulin was 3.2 h (SD = 0.82). Two patients achieved at least a partial response by Macdonald criteria. One of these patients remains progression free and off treatment more than 24 months beyond his initiation of verubulin. Five patients had stable disease. Median progression-free survival (PFS) across all patients was 8 weeks, and the 6-month PFS rate was 21 %. The combination of verubulin at the previously determined single-agent maximum tolerated dose of 3.3 mg/m² with carboplatin in patients with recurrent/refractory GBM is safe and well tolerated. In this patient population with a highly vascularized tumor, no cerebral hemorrhage was observed.