All-trans retinoic acid and low-dose cytosine arabinoside for the treatment of 'poor prognosis' acute myeloid leukemia

Thirty-three patients with 'poor prognosis' acute myeloid leukemia, no longer suitable for aggressive chemotherapy, were treated with daily oral all-trans retinoic acid (45 mg/m²) daily and subcutaneous cytosine arabinoside (20 mg standard dose twice a day, day 1 to 10, every 4 weeks). Seventeen patients were males and 16 females, the median age was 67 (range 39-82 years). Eleven patients were at onset of disease, 15 were refractory to previous conventional therapies, three were in first relapse and three in second relapse and one patient had a secondary AML. Seventeen patients had a bone marrow blast infiltration <50% and 16 ≥ 50%. A total of 16 (48%) patients entered complete remission; the rate of complete remission increased to 88% in those patients (n = 17) with <50% blast infiltration at the time of entering the study. Seventeen patients (52%) were resistant. The difference in response to therapy, according to bone marrow blast percentage (<or ≥ 50%), was statistically significant (P <0.001). Median duration of complete remission was 34.4 weeks (range 6.4-62.8). Mild to moderate hematologic toxicity was the most common side-effect. In conclusion all-trans retinoic acid and low-dose cytosine arabinoside appears to be an effective regimen for inducing complete remission in 'poor prognosis' acute myeloid leukemia and patients with <50% bone marrow infiltration are likely to represent the ideal target to receive this combination therapy.