Continuous intratumoral infusion of methotrexate for recurrent glioblastoma: a pilot study

Five patients with documented recurrences of glioblastoma multiforme were given continuous infusions of methotrexate delivered intratumorally using implantable catheters and subcutaneous refillable pumps. A continuous infusion of methotrexate (1 mg/d) was begun with concomitant oral administration of folinic acid. The methotrexate dose was increased every 2 weeks to 3, 10, 30, and, ultimately, 75 mg/d in two patients. Samples of serum and ventricular cerebrospinal fluid (CSF) were obtained to determine the levels of methotrexate and total bioactive folates, and brain tissue was obtained from two patients for determination of methotrexate concentration. The patients survived from 7 to 49 weeks after the implantation of the infusion device. Neither the clinical examination nor sequential radiological studies gave clear evidence of reduction in tumor size. Pneumonia developed in one patient, and mild hepatitis and increased seizure frequency in another. Methotrexate was stable in the delivery system over 12 days, and ventricular CSF reached steady-state levels by 5 days. Steady-state ventricular CSF levels of methotrexate were higher than serum levels in some patients, while the reverse was true in others. Levels of total bioactive folates in the CSF did not increase above the normal range. Methotrexate concentrations were highest at the center of the tumor, but measurable amounts of methotrexate were detectable in all areas of the brain. At autopsy in four patients, variable liquefactive necrosis of the brain tumors was seen, and viable tumor was found at the periphery of the tumor bed. These preliminary results suggest that it is technically feasible to infuse methotrexate into brain tumor cavities, and show that little central nervous system or systemic toxicity was encountered in five patients. Better delineation of the safety and efficacy of this therapeutic approach will require further clinical trials.