Assay of anti-cancer drugs in tissue culture: Relationship of relapse free interval (RFI) and in vitro chemosensitivity in patients with malignant cerebral glioma

One hundred and seventeen patients with cerebral glioma (Kernohan grades III and IV) were treated with adjuvant chemotherapy using procarbazine (PCB), CCNU and vincristine (VCR) following whole head irradiation. Cell cultures were prepared from 40 patients in this series and their sensitivity to each cytotoxic drug was assessed in a mictotitration assay with 35 S-methionine incorporation as the end point. Twenty-two of forty (55%) patients responded to PCB and/or CCNU in vitro, and sensitivity to these drugs was linked with increased RFI, whilst sensitivity to VCR was not. The RFI of patients who had responded to PCB or CCNU in vitro was significantly longer than the RFI of patients whose tumours failed to respond in vitro or patients who had not been tested. There was no difference in sex ratio, extent of operation, radiation dose and degree of steroid cover between responders, non-responders and untested groups. Grade III tumours tended to be more sensitive in vitro than grade IV tumours. The age of patients also influenced in vitro chemosensitivity. Patients with chemosensitive tumours in vitro tended to be younger than patients with insensitive tumours in vitro. Further statistical analysis, taking into account these prognostic factors, indicated an association between chemosensitivity in vitro and RFI.