Leukeran 
Active substance: Chlorambuzil
Manufacturer: GlaxoSmithKline
Extract from the prescribing information:
"Chlorambucil is a carcinogen in humans. Chlorambucil is probably mutagenic and teratogenic in humans."
"There are many reports of acute leukemia arising in patients with both malignant and non-malignant diseases following chlorambucil treatment."
The above has been extracted from the Leukeran prescribing information on the GlaxoSmithKline webpages.