Phase III, Randomized, Multicenter Study to Assess the Efficacy and Safety of HuM195 (Recombinant Humanized Anti-CD33 Monoclonal Antibody) in Combination With Standardized Chemotherapy Compared to Standardized Chemotherapy Alone in the Treatment of Patients With Refractory or First-Relapsed Acute Myelogenous Leukemia (AML)

Inclusion Criteria

DISEASE CHARACTERISTICS: Histologically proven acute myelogenous leukemia (AML) that may
have been primary AML, secondary AML, or preceded by hematologic disorder All FAB subtypes
except M3 Must meet one of the following three criteria: First relapse within 1 year after
documentation of a previous complete remission (CR) achieved by chemotherapy Refractory to
prior chemotherapy comprised of a minimum of 1 induction course, including cytarabine at a
minimum of 500 mg/m2 (e.g., 100 mg/m2/day for 5 days) plus an anthracycline No high dose
cytarabine (no cumulative dose greater than 3 g/m2) First relapse from a previous CR with
subsequent autologous bone marrow transplantation (BMT), only if all of the following
criteria are met: First BMT At least 100 days but less than 1 year posttransplantation At
least 25% cellularity of the bone marrow Previous BMT included full hematopoietic
recovery, defined by all of the following: Hemoglobin at least 10 g/dL (without
transfusion) Platelet count at least 100,000/mm3 (without transfusion) Absolute neutrophil
count at least 1,500/mm3 No transplantation candidates Bone marrow blasts (leukemic cells)
greater than 10% No chronic myelogenous leukemia in blast crisis No active CNS leukemia

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Karnofsky 50-100% Life
expectancy: Not specified Hematopoietic: See Disease Characteristics Hepatic: Bilirubin
less than 2.0 mg/dL (unless related to Gilbert's disease or due to leukemic infiltration)
SGOT or SGPT no greater than 4 times upper limit of normal (unless related to AML) Renal:
Creatinine less than 2.0 mg/dL (unless related to AML) Cardiovascular: Left ventricular
function normal No unstable cardiac arrhythmias, unstable angina pectoris, or myocardial
infarction within the past 6 months No New York Heart Association class III or IV heart
disease No electrocardiogram evidence of active ischemia Other: Not pregnant or nursing
Negative pregnancy test Fertile patients must use effective contraception during and for 1
month after study HIV negative No other active malignancy requiring therapy No active
serious infection that is uncontrolled by antimicrobial therapy Medically stable No
significant organ dysfunction

PRIOR CONCURRENT THERAPY: Biologic therapy: See Disease Characteristics At least 30 days
since prior experimental biologic therapy (e.g., interleukin-2) No concurrent biologic
therapy, including bone marrow transplantation Chemotherapy: See Disease Characteristics
For first relapse AML with recent or prior chemotherapy: Prior hydroxyurea given as a
short course (up to 48 hours) allowed, if needed, to reduce the peripheral leukocyte count
Hydroxyurea must be discontinued prior to study For refractory AML with recent or prior
chemotherapy: Greater than 2 weeks since prior chemotherapy except hydroxyurea given as
above No other concurrent chemotherapy Endocrine therapy: Not specified Radiotherapy: No
concurrent radiotherapy Surgery: Not specified Other: No other concurrent experimental
therapy Concurrent therapy for other preexisting diseases allowed