Which of the following chemotherapeutic drugs has selective action on hypoxic tumor cells -

Ans. is 'a' i.e., Mitomycin Mitomycin belongs to the antibiotic anticancer group.These anticancer drugs are obtained from microorganisms and have prominent antitumour action.Mechanism of action of mitomycinIntracellularly it is converted to a metabolite, which acts as an alkylating agent that kills cells at G1-M phase.It inhibits DNA synthesis and cross links DNA at the N6 position of adenine and at the O6 and N7 position of guanine.In addition single stranded breakage of DNA and chromosomal breaks are caused by mitomycin.Some important points about mitomycin.Mitomycin acts preferentially on hypoxic cellsIt is a potent radiosensitizerIt is absorbed consistently from G.L tract so it administered by intravenous infusionUses of mitomycinUsed as a combination therapy for the t/t of carcinoma of the colon or stomach.It is also used by direct instillation into the bladder to treat superficial carcinomas of bladder.Adverse effectMajor toxic effect is myelosuppression (Pancytopenia)Hemolytic uremic syndrome, it is caused due to drug induced endothelial damage.