Inclusion Criteria

DISEASE CHARACTERISTICS: Histologically proven relapsed acute lymphocytic leukemia, acute
myeloid leukemia, or blastic phase chronic myelogenous leukemia Refractory to conventional
therapy and other therapies of higher priority May have concurrent extramedullary relapse
except for testicular relapse or other extramedullary sites that may require concurrent
radiotherapy

PATIENT CHARACTERISTICS: Age: 21 and under Performance status: ECOG 0-2 Life expectancy:
At least 2 months Hematopoietic: Not specified Hepatic: Bilirubin no greater than 2.0
times normal SGOT or SGPT less than 5 times normal Renal: Creatinine no greater than 1.5
times normal Other: Able to take oral liquid medication No GI neuropathy No other
condition that may affect absorption of drug No diabetes mellitus Not pregnant or nursing
Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY: Biologic therapy: Prior bone marrow transplantation (BMT) or
peripheral blood stem cell transplantation (PBSCT) allowed and recovered At least 2 weeks
since prior cytokine therapy and recovered No concurrent immune modulator therapy No
concurrent cytokines including interleukin-11, interleukin-2, and epoetin alfa
Chemotherapy: At least 2 weeks since prior chemotherapy (4 weeks for nitrosoureas) and
recovered No more than 3 prior chemotherapy regimens No other concurrent chemotherapy
Endocrine therapy: No concurrent steroids Radiotherapy: No prior craniospinal radiotherapy
Prior total body irradiation allowed as part of BMT or PBSCT and recovered Concurrent
radiotherapy for localized painful lesions allowed Surgery: Not specified Other: No
concurrent metoclopramide or cisapride to maintain motility or gastric emptying No
concurrent H2 antagonists No concurrent proton pump inhibitors No concurrent antacids for
gastritis, gastroesophageal reflux, or ulcers (gastric or duodenal) No antacid therapy for
6 hours before and for 90 minutes after topotecan administration