Phase I trial of imatinib mesylate, hydroxyurea and vatalanib for patients with recurrent glioblastoma multiforme (GBM)

Abstract

2027 Background: Recent studies have demonstrated promising anti-glioma activity of imatinib mesylate (IM) and hydroxyurea (H). Angiogenesis is one of the hallmarks of GBM with VEGF as a key regulator. This study attempts to extend the efficacy of IM and H by adding a VEGF receptor inhibitor, vatalanib (V; PTK787/ZK22584). Methods: We employ a ‘3+3‘ dose escalation design to determine the maximum tolerated dose (MTD) and dose-limiting toxicity (DLT) of IM and V when administered with fixed dose of H in adult recurrent GBM patients with < 3 prior recurrences, KPS = 70% and adequate organ function. Patients are stratified based on concurrent enzyme-inducing anticonvulsant (EIAC) administration, and both strata (A- not on EIAC and B- on EIAC) are independently dose-escalated. Initial dose levels for stratum A: IM - 400 mg/day; H - 500 mg bid; V- 250 mg bid and for stratum B: IM- 500 bid; H-500 mg bid; V- 500 mg bid. Patients are given only V on day 1–7 of cycle 1 and then IM+H+V daily thereafter. Only cycle 1 is 35 days with subsequent cycles of 28 days. Response is evaluated every other cycle. Pharmacokinetic (PK) studies are performed on days 7 and 35 of cycle 1. Results: Thirty-five recurrent GBM patients have enrolled. The median age is 51.5 (range 31 to 75), 66% are male, and 51% are on EIAC. One DLT (grade 3 thrombocytopenia) occurred in a stratum A patient on dose level three . For stratum B, two DLTs (grade 3 hypertension and ALT elevation) occurred in a patient on dose level two and one DLT (grade 3 fatigue) occurred in a patient on dose level three. MTDs for each stratum have not been reached and accrual is ongoing. PK results are pending. Ten partial responses (29%) have been observed and nine patients remain on study including three who have received more than 6 cycles of therapy. Conclusions: Combination of imatinib, hydroxyurea and vatalanib is safe and well-tolerated with an encouraging rate of radiographic response. Further accrual is in progress to define the MTD. No significant financial relationships to disclose.