RELATIONSHIP OF [H-3] ARA-C INCORPORATION AND RESPONSE TO THERAPY WITH HIGH-DOSE ARA-C IN AML PATIENTS - A LEUKEMIA INTERGROUP STUDY

Pretherapy bone mar-row (BM) aspirates of 143 patients with acute myeloid leukemia (AML) were incubated simultaneously with bromodeoxyuridine (BrdU) and tritiated cytosine arabinoside ([H-3]Ara-C) to determine the labeling index (LI) and extent of [H-3]Ara-C incorporation. Of 143 AML patients, 121 received high-dose Ara-C (HDAra-C) as a single agent for induction therapy (55 newly diagnosed, 66 in first relapse), whereas 22 received HDAra-C plus mAMSA. The data demonstrate that a subset of patients who will fail HDAra-C remission induction therapy because of drug-resistant disease can be prospectively identified on the basis of the low amount of Ara-C incorporated by their leukemia cells.