Salvage chemotherapy with CPT-11 for recurrent glioblastoma multiforme

A prospective Phase II study of CPT-11 in adult patients with recurrent supratentorial glioblastoma multiforme (GBM).

Forty patients (25 men, 15 women) ages 32-71 years (median 59), with recurrent GBM were treated. All patients had previously been treated with surgery and involved field radiotherapy (median dose 60 Gy; range 59-60). Additionally, all patients were treated with adjuvant chemotherapy (BCNU in 20, PCV in 18, Procarbazine in 2). Twenty-five patients (62%) were on anticonvulsants (phenytoin in 15, carbamazepine in 10) and 26 patients (65%) were on dexamethasone. Recurrent disease was defined by neuroradiographic disease progression (>25% increase in tumor dimensions) using gadolinium-enhanced MR imaging. The starting dose of CPT-11 was 400 mg/m2 followed in three weeks by 500 mg/m2, operationally defined as one cycle. At week 6, all patients were evaluated with MRI and neurological examination.

All patients were evaluable. Two doses (one cycle) of CPT-11 were administered to all patients. CPT-11-related toxicity included: diarrhea (16 patients, 40%); thrombocytopenia (9 patients, 23%); and neutropenia (6 patients, 15%). No patient required transfusion nor was treatment for neutropenic fever required. No treatment-related deaths were observed. All patients demonstrated progressive disease following one cycle of CPT-11.

The lack of response to CPT-11 in this patient group with recurrent GBM suggests either CPT-11 has minimal activity or CPT-11 doses/schedule utilized in this study were sub-optimal. The latter is supported by the modest toxicity seen in this study and the previously documented enhanced clearance of CPT-11 in patients on anticonvulsants and dexamethasone.