Penetration of Idarubicin into Malignant Brain Tumor Tissue

Anthracyclines are effective in breast cancer and have in vitro cytotoxicity in glioma. In patients with glioma anthracyclines are not effective possibly because the hydrophilic drugs do not reach cytotoxic levels in tumor tissue. Idarubicin is more lipophilic than the other anthracyclines and is more cytotoxic in glioma cell lines. The uptake of idarubicin and its major metabolite idarubicinol in brain tumor tissue were measured in a patient with a brain metastasis from breast cancer and in 4 patients with malignant glioma after an oral dose of idarubicin (45 mg/m² in 1 patient; 25 mg/m² in 4 patients), given 15–24 h before brain tumor resection. The concentrations of idarubicin and of idarubicinol in tumor tissue exceeded the concurrent plasma concentrations as well as the peak plasma concentrations in all cases. The median tumor: concurrent plasma ratio of idarubicinol was 5.7 (range 1.7–18). The concentration of idarubicinol in the marginal zone between brain and tumor tissue was lower than in central tumor tissue, but was still higher than the plasma concentration in 2 of the 3 examined cases. Bone marrow suppression (platelets CTC grade 2, granulocytes CTC grade 4) occurred after a single dose of 45 ml/m². No toxicity was seen at a dose of 25 mg/m². These results, the in vitro activity of idarubicin in glioma, the convenience of oral administration, and its toxicity profile make clinical studies with idarubicin in malignant glioma, and perhaps also in brain metastases from breast cancer worthwhile.