OUTLINE: This is a randomized, double blind, placebo controlled, multicenter study. Patients receive the matrix metalloprotease inhibitor AG3340 (at one of two dosages) or placebo, orally twice a day, beginning on day 1. Patients receive mitoxantrone by intravenous infusion on day 1 and prednisone orally twice daily beginning on day 1. Treatment course is repeated every 3 weeks in the absence of unacceptable toxicity. Mitoxantrone and/or prednisone may be discontinued or switched at the investigator's discretion.