Glioma remission promoted by combining vaccination and radiation.(Brief Article)

2002 AUG 21 - (NewsRx.com & NewsRx.net) -- by Maria G. Essig, MS, ELS, senior medical writer - Vaccination alone stimulated the growth of intracranial glioma tumors, but the addition of radiation therapy induced an immune response that destroyed tumor tissue in a rat model.

Martin R. Graf and his colleagues at Virginia Commonwealth University and Cedars-Sinai Medical Center (Los Angeles) investigated the effects of vaccination and vaccination plus radiation therapy on rats carrying 5-day-old identical intracranial glioma tumors.

The investigators treated the rats with subcutaneous inoculation of irradiated T9.F glioma cells (5x10[superscript]6) or inoculation combined with whole head irradiation (15 Gy).

Vaccination alone failed to damage the tumors, which lacked evidence of inflammation, edema, or hemorrhage; instead, tumor growth increased and rat survival time decreased compared with unvaccinated control rats. Examination revealed 10 times the lymphoid infiltrate (per mg tumor) in the gliomas from the vaccinated rats than in tumors from the control rats. Graf and his collaborators speculated that "the vaccination had induced immune cells to localize to the i.c. glioma."

Rats that received radiation treatment prior to vaccination experienced a significant increase in survival compared with the controls and a 45% complete remission rate. Tumor sites of the surviving rats contained mononuclear cells including hemosiderin-carrying macrophages, but no viable tumor cells (Irradiated tumor cell vaccine for treatment of an established glioma. I. Successful treatment with combined radiotherapy and cellular vaccination. Cancer Immunology, Immunotherapy, 2002;51(4):179-189).

Surviving rats challenged with subcutaneous delivery ...