Busulfan

Overview
Busulfan is a chemotherapy drug that is a cell cycle non-specific alkylating agent (slows the growth of cancer cells). More specifically it belongs to a subclass of alkylating agents known as alkyl sulfonates. It is marketed in the U.S. by GlaxoSmithKline under the brand name Myleran, and has been in clinical use since 1959. Busulfan is also available in an IV formulation marketed as Busulfex by PDL BioPharma, Inc. Its chemical designation is 1,4-Butanediol dimethanesulfonate.

Uses
Currently, its main uses are in bone marrow transplantation, especially in chronic myelogenous leukemia (CML), where it is used as a conditioning drug. Busulfan can control tumor burden but cannot prevent transformation or correct cytogenic abnormalities. Though not as common, it may also be used for Chronic Lymphocytic Leukemia (CLL).

Its mechanism of action through alkylation produces DNA-DNA and DNA-protein cross linking. The resulting covalent bonds inhibit DNA, RNA, and protein synthesis. The inhibition of DNA synthesis subsequently produces a cytotoxic effect.

The drug was recently used in a study to examine the role of platelet-transported serotonin in liver regeneration.

Toxicity and side effects
Toxicity may include interstitial pulmonary fibrosis, hyperpigmentation, seizures, hepatic (veno-occlusive disease) and wasting syndrome. Phenytoin may be used concurrently to prevent the seizures.

1,4-Butanediol dimethanesulfonate is listed by the IARC as a Group 1 carcinogen.

Busulfan also induces thrombocytopenia, a condition of lowered blood platelet count and activity.

Historical
Busulfan use to be the standard of treatment for Chronic Myeloid Leukemia (CML) until it was replaced with the new gold standard, Imatinib.