Unexpected in vitro chemosensitivity of malignant gliomas to 4-hydroxyperoxycyclophosphamide (4-HC)

To individually tailor chemotherapy for patients with malignant gliomas according to tumor chemosensitivity, a rapid assay system which can be performed with a high success rate is needed. The fluorescent cytoprint assay (FCA) can assess multiple chemotherapeutic agents using small (approximately 500 cells) tumor aggregates very quickly (approximately 1 wk). Tissue samples from 51 patients with malignant gliomas obtained either at time of initial diagnosis (n = 34) or at recurrence were assayed using this method. The assay success rate approached 90% in those culture samples which were histologically verified as tumor. A meaningful number of agents could be tested both on samples obtained by stereotactic biopsy (median, 5) and on specimens from more extensive resections (median, 6). One hundred ninety-three FCAs were performed on a samples obtained from 36 patients. In only twenty six assays (14%) was an agent deemed sensitive (> 90% cell kill) to a chemotherapeutic agent. Sixty-two percent of sensitive FCAs were observed in tumors tested against the activated analog of cyclophosphamide, 4-hydroxyperoxycyclophosphamide (4-HC), where a sensitivity rate (# samples sensitive/total tested against agent) of 64% (95 % CI, 36.6-77.9%) was noted. This rate was significantly higher than with any other agent tested (p = 0.012, two sided McNemar's test) and was not affected by age, histology or disease status. We conclude that: (1) the FCA represents a feasible method for quickly assaying tumors for sensitivity to multiple chemotherapeutic agents; and (ii) malignant gliomas may be particularly sensitive to 4-HC.