Two antiemetic regimens do not impair chemical xenogenization induced in vivo by 5-(3,3-dimethyl-1-triazeno)-imidazole-4-carboxamide.

The possible interference with 5-(3,3-dimethyl-1-triazeno)-imidazole-4-carboxamide (DTIC)-mediated chemical xenogenization (CX) by antiemetic drugs was studied. DTIC was given alone or in combination with either dexamethasone or metoclopramide plus orphenadrine hydrochloride plus diazepam to CD2F1 mice bearing the histocompatible L1210 leukemia. Tumor cells were collected from treated animals and inoculated into histocompatible untreated and drug-treated recipients, for eight transplant generations. More than 50% of intact hosts rejected tumor cells between the fourth and sixth transplant generation, independently of antiemetic treatments. Positive controls treated with DTIC plus quinacrine (QC) confirmed that this antimutagenic compound entirely abrogates CX. The present results point out that the antiemetic regimens investigated in this study do not prevent CX. Since DTIC treatment requires intensive antiemetic support in man, these data are of clinical relevance for CX-oriented immunochemotherapy protocols.