ICD-10 Specific code C92.1: Chronic myeloid leukaemia

Busulfan is a potent cytotoxic agent and a bifunctional alkylating agent. In aqueous media, release of the methanesulphonate groups produces carbonium ions which can alkylate DNA, thought to be an important biological mechanism for its cytotoxic effect.

Ifosfamide is an antineoplastic, a cytotoxic alkylating agent. It is a prodrug and shows no in vitro cytotoxic activity until activated by microsomal enzymes. The cytotoxic activity of ifosfamide (alkylation of the nucleophilic centres in the cells) is associated with the activated oxazaphosphorine ring hydroxylated at the C4 atom which interacts with DNA-DNA cross linking. This activity manifests itself by blocking the late S and early G2 phases of the cell cycle.

Recombinant interferon alfa-2b is a sterile, stable, formulation of highly purified interferon alfa-2b produced by recombinant DNA techniques. Interferons exert their cellular activities by binding to specific membrane receptors on the cell surface. Recombinant interferon alfa-2b has exhibited antiproliferative effects in studies employing both animal and human cell culture systems as well as human tumour xenografts in animals. It has demonstrated significant immunomodulatory activity in vitro.

Thiotepa is a polyfunctional cytotoxic agent related chemically and pharmacologically to the nitrogen mustard. The radiomimetic action of thiotepa is believed to occur through the release of ethylene imine radicals that, as in the case of irradiation therapy, disrupt the bonds of DNA, e.g. by alkylation of guanine at the N-7, breaking the linkage between the purine base and the sugar and liberating alkylated guanine.