Daunorubicin
Daunorubicin works to prevent cell growth by preventing DNA replication. It is an anthracycline. It's known for nasty side effects, most notably cardiac damage. It has a cumulative effect, so there is a lifetime maximum dosage.
More information can be found here:
http://www.pfeist.net/ALL/anth.html
Late Effects: Heart [From Pediatric Oncology Resource Center]