Therapy of an experimental glioma with systemic or intraneoplastic methotrexate or radiation

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Abstract
An intracranial mouse glioma model was used to study the effectiveness of chemotherapy with methotrexate (MTX) or radiotherapy. Maximum tolerable doses of MTX were established by toxicity studies in nontumor-bearing mice for the i.p. and intracerebral routes of drug administration with and without leucovorin as an antidote. These maximum tolerable doses were given by the i.p. route or directly into the tumor to mice bearing intracerebral tumors. The glioma model was extremely useful for assessing the modalities studied, including repeated intraneoplastic injection of MTX. Dosage schedules were successfully developed for administering large amounts of MTX and for preventing systemic toxicity by the administration of the antidote. Radiotherapy in single doses of 800 rads delayed the median day of death and produced several long-term survivors. Higher doses were toxic. I.p. or intraneoplastic MTX was completely ineffective as a chemotherapeutic agent for this tumor, even though very large amounts could be delivered due to the protection from systemic toxicity afforded by leucovorin. MTX is a poor chemotherapeutic agent for this experimental brain tumor, but the technique of intraneoplastic administration of chemotherapeutic agents is feasible with this model system and should be studied further.