Phase II preradiation R115777 (tipifarnib) in newly diagnosed GBM with residual enhancing disease.

Glioblastoma multiforme (GBM) is a lethal primary malignant brain tumor in adults. R115777 (tipifarnib) is an oral agent with antiproliferative effects, being a potent and selective inhibitor of farnesyltransferase. This multicenter, open-label phase II study was designed to evaluate the efficacy and safety of R115777 given after surgery and prior to radiation in patients with newly diagnosed and residual enhancing GBM. Following surgery, an MRI confirmed the presence of residual enhancing tumor. Patients on enzyme-inducing antiseizure drugs (EIASDs) received 600 mg twice per day, and those not on EIASDs received 300 mg twice per day. One to three monthly cycles of R115777 were administered, and radiation was initiated with progression or after three cycles. A cycle consisted of 3 weeks of continuous R115777 followed by a 1-week rest. MRI was done monthly. The primary end point was overall survival; secondary end points were tumor response rate and toxicity. A total of 28 confirmed GBM patients entered the study; 15 patients (54%) were on EIASDs. The overall median time of survival was 7.7 months. There were no tumor responses. Eight patients (29%) had stable disease as the best response. The study was stopped early due to progression of the disease in 12 patients (48%). A total of 24 patients (85%) were off study before the planned treatment schedule for radiation therapy. R115777 administered prior to radiation therapy in patients with newly diagnosed GBM and residual enhancing disease did not result in any measurable responses or improvement in survival. R115777 administered prior to radiation therapy is not recommended for patients with newly diagnosed GBM.