Potential cardiotoxicity with mitoxantrone.

Mitoxantrone is a promising new agent developed in an attempt to find drugs with a broad spectrum of antitumor activity and devoid of cardiotoxicity. In a phase II clinical trial for refractory metastatic breast cancer, we observed congestive heart failure in four of 31 high-risk patients either during or after treatment with this drug. This report calls attention to that observation, and recommendation is made that further evaluation of this agent include careful cardiac monitoring.