CASE LEARNING OBJECTIVES
Recognize the major prognostic factors in childhood pre–B-cell acute lymphocytic leukemia
Identify the treatment-related complications associated with the therapy for acute lymphocytic leukemia
Identify the role of thiopurine methyltransferase metabolism with respect to 6-mercaptopurine toxicity
Develop a plan to evaluate the patient's current problems and determine if they are related to his ability to metabolize 6-mercaptopurine and select an appropriate new dose for this patient
Describe the late effects of chemotherapy related to the treatment of acute lymphocytic leukemia
Chief Complaint (Mother's)
"My son keeps having repeated episodes of infection and low blood counts. He needs to be transfused more often than the other patients I know who are on the same protocol."
History of Present Illness
MC is a 12-year-old Hispanic male who was diagnosed with pre–B-cell acute lymphoblastic leukemia (ALL) at age 11. His presenting WBC count was 7.5 × 103/mm3 (7.5 × 109/L) with 80% leukemic cells. He had no testicular disease and his cerebrospinal fluid showed no leukemic cells. Cytogenetic evaluation of his leukemic cells showed random chromosomal loss and gain. Tumor-cell ploidy showed a DNA content of 1.15. He had a prompt response to induction therapy with a morphologic remission at day 8. His end-of-induction minimal residual disease (MRD) was low. He recently completed his final "delayed intensification" treatment module and began "maintenance" treatment 5 months ago. Since the start of maintenance, he has had two admissions for fever of 101.3°F (38.5°C) and ANC of 250–300/mm3 (0.25–0.30 × 109/L), each lasting 7 days. Both episodes were associated with negative blood cultures. On each occasion, his maintenance chemotherapy [daily oral 6-mercaptopurine (6MP) and weekly oral methotrexate] was stopped until his ANC was above 500/mm3 (0.50 × 109/L), and he was afebrile for 48 hours.
Full-term infant, uncomplicated birth, and neonatal history
ALL s/p chemotherapy; history of 1 previous admission for fever and neutropenia during the delayed intensification phase of treatment. He has received 2 prior platelet transfusions, one each during induction and delayed intensification phases of treatment. He has received 3 prior RBC transfusions, the last of which was greater than 3 months ago
Completely up-to-date on childhood immunizations for his age up to the time of his diagnosis for ALL
The patient is currently in seventh grade at an elementary school in a disadvantaged neighborhood where the first language of many residents is Spanish. He is a good student, and his parents were involved in his school and community in a positive way. There are two additional siblings in the home: a 6-year-old sister in kindergarten and a ...