Cytarabinebased Combination Regimens

The largest series incorporating AML-type chemotherapy in patients with myeloid blast phase (blast count > 30%) involved 162 patients treated at MD Anderson Cancer Center over an 11-year period from 1986 to 1997.23 Ninety patients received intensive combination chemotherapy, largely high-dose cytarabine-based. Overall, 28% of the patients responded to treatment, with CHR in 8% of the patients, and an additional 7% achieving all criteria for CHR, but with incomplete platelet count recovery. In addition, 11% of the patients achieved a return to chronic phase, and 2% of the patients were termed a partial response. The duration of response was approximately 4 months, which corresponded with survival as well. In a series of patients treated at the Karolinska Hospital in Sweden,24 47% of 83 patients with accelerated or myeloid blast-phase disease, treated with an anthracycline/cytarabine-based regimen, achieved a return to chronic phase, the definition of which was less stringent than the MD Anderson data. Overall survival was similar, however, in the 4-6 month range. In this series, patients with accelerated-phase disease had similar responses to those of blast-phase, although they demonstrated a slight, but statistically insignificant, improvement in survival. These studies, as well as numerous other smaller experiences,25-29 have demonstrated that standard AML-type regimens have limited efficacy in advanced-phase patients and, despite widespread application, it is not clear that higher-doses of ara-C are better than standard doses in this setting.

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