Therapy of solid Walker carcinosarcoma 256 with bleomycin after synchronization with hydroxyurea.

Rats with the solid Walker carcinosarcoma 256 were synchronized with hydroxyurea (6 x 50 mg/kg or 1 x 300 mg/kg body weight) and treated with bleomycin (32 mg/kg body weight) at different time points thereafter. Bleomycin clearly affects Walker carcinosarcoma cells at the G1/S boundary or in S-phase. The improvement in the results of bleomycin therapy after pretreatment with hydroxyurea can mainly be accounted for by the synchronization of the tumour cells.