Attempted Prevention of Blast Crisis in Chronic Myeloid Leukemia by the use of Pulsed Doses of Cytarabine and Lomustine A Cancer and Leukemia Group B Study

Abstract

An attempt to prevent the blast crisis in chronic myeloid leukemia by the use of pulsed doses of (cytarabine cytosine arabinoside) and lomustine was attempted as a cooperative group study by Cancer and Leukemia Group B. The basis for this study was to delay the development of blast crisis by pulsing dose of drugs known to be effective against emerging “blast” cells. The experimental arm which consisted of cytarabine and lomustine did not produce overall results superior to conventional treatment with busulfan. This was related to the non-hematologic effects of the combination which produced significant gastrointestinal toxicity leading to relatively early discontinuation of the combination. Nevertheless, the trial design allowed relatively prompt discontinuation of experimental arm and cross-over to conventional treatment with either hydrea or busulfan. No evidence existed that the use of new drug combinations in CML prejudiced the patient's chance to response to conventional chemotherapy. Thus, a role model for future trials in this disease was developed. With the development of the interferons and other experimental forms of therapy this conceptual development may be of significance.

Key Words:

• Chronic myeloid
• leukemia
• CML
• blast
• crisis Ara-C
• cytarabine
• cytosine arabinoside lomustine