Treatment of adult patients with relapsed or refractory acute lymphoblastic leukemia (ALL)

Relapsed acute lymphoblastic leukemia (ALL) in an adult is rarely cured. The majority of adult patients with relapsed ALL who are subsequently cured of their disease are given chemotherapy to achieve a second complete remission (CR) followed by a successful allogeneic bone marrow transplant. Overall, only a minority (typically 10% to 20%) of these relapsed patients in second CR are cured of their disease by an HLA-identical sibling allogeneic transplant. Many chemotherapy reinduction protocols have been tested in the setting of relapsed ALL. High-dose regimens appear to result in a greater incidence of second CRs compared with reinduction with standard vincristine, prednisone, anthracycline-based regimens. A combination of high-dose Ara-C (HDAC) and an anthracycline has the greatest likelihood of achieving a first CR in ALL patients with refractory disease or a second CR in relapsed patients. We have recently explored the activity of HDAC combined with a single a high dose of an anthracycline (idarubicin) or an anthracenedione (mitoxantrone) in adult patients with ALL. Our results indicate that these regimens are extremely active in the relapsed/refractory setting as well as in previously untreated adults. In order to compare this approach with standard therapy for ALL, we have started to accrue patients to a phase III trial, which will prospectively randomize patients to induction with Ara-C and high-dose mitoxantrone versus a standard vincristine, prednisone, anthracycline-based regimen.