Improved tolerance of vincristine by glutamic acid. A preliminary report.

In a murine model system, glutamic acid has demonstrated host protective properties during administration of vincristine (VCR). Subsequently, glutamic acid has been evaluated in patients receiving VCR during adjuvant chemotherapy for stage II carcinoma of the breast. The cumulative VCR dosage and toxicities incurred in 16 patients receiving glutamic acid have been compared to those observed in 88 patients who previously received VCR without glutamic acid in the same chemotherapy program. All patients received VCR 1.0 mg/m2 weekly for 6 weeks with dose modification for neurotoxicity. Treatment patients received glutamic acid 1.5 grams p.o. daily in three divided doses during the induction course. Of the 16 treatment patients, 9 (56%) received 100% ideal dosage of VCR during induction therapy whereas only 24 of 88 (27%) comparison patients attained this dosage level (p less than .025). Gastrointestinal and hematologic toxicities were similar in both groups. These preliminary results suggest the need for an expanded trial of this agent during administration of VCR.