title: Detection of induced tumour-resistance to cyclophosphamide by the in vitro short term test.
abstract: Treatment of the solid Walker carcinosarcoma of the rat for a period of one year with cyclophosphamide (40 mg/kg at each passage; tumours were transplanted weekly) resulted in the formation of a cyclophosphamide-resistant tumour cell line. Without further treatment, animals injected with non-treated or cyclophosphamide pre-treated cells survived for 10 days on an average. After therapy with cyclophosphamide (2 x 38 mg/kg), rats with non-treated tumour cells survived 22 days whereas those with pre-treated tumours survived only for 17 days. Tumour cells which were shown to be sensitive in vivo also exhibited a larger reduction in 3H-thymidine and 3H-uridine incorporation in the in vitro short term test after incubation with urine from cyclophosphamide-treated rats or with 4-hydroperoxy-cyclophosphamide. The resistance to cyclophosphamide which was detected in animal experiments with Walker carcinosarcoma can therefore also be observed using the in vitro short term test.
mesh_terms: D000818:Animals; D001711:Biotransformation; D002279:Carcinoma 256, Walker / Q000188:drug therapy* / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D003520:Cyclophosphamide / Q000009:adverse effects* / Q000378:metabolism / Q000627:therapeutic use; D004351:Drug Resistance; D066298:In Vitro Techniques; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism; D051381:Rats; D013997:Time Factors
chemical_list: D003520:Cyclophosphamide