This study investigated the effect of antioxidant vitamins on toxicity from radio-immunotherapy (RAIT) and thereby allow higher escalation of RAIT doses.

Lipophilic vitamins A and E were administered i.p. and hydrophilic vitamin C was administered i.m. for 14 days (3 days pre-RAIT through 11 days post-RAIT) alone or with bone marrow transplantation (BMT) to either BALB/c mice for toxicity studies or to nude mice bearing s.c. GW-39 human colonic cancer xenografts for therapy studies.

Administration of vitamins (equivalent of 3.5 IU/day vitamin A, 0.107 IU/day vitamin E and 4.0 mg/day ascorbic acid) to mice along with BMT increased the MTD by 42% and reduced body weight loss associated with RAIT.

Vitamins also reduced the magnitude of RAIT-induced myelosuppression.

As early as day 7 after RAIT, vitamins increased WBC counts following both a 400 microCi and a 500 microCi dose. On day 14 after the 400 microCi dose of RAIT (day 7 post-BMT), the additive effect of BMT and vitamin could be detected.

Tumor growth was not adversely affected by vitamin administration.

Blumenthal, R.D. et al. Int J Cancer 2000 Apr 15;86(2):276-80.