Lay Summary: There is now evidence that GLeevec is very effective in Philadelphia chromosome positive ALL.
Philadelphia-positive ALL is a very difficult disease to treat successfully. In the recent past, the standard approach was to use daunorubicin/vincristine/prednisone-based induction therapy to achieve remission and then, if the patient was a reasonable candidate and a donor could be found, to perform an allogeneic transplant. Now, the use of tyrosine kinase inhibitor therapy may be altering this strategy. Single-agent treatment with imatinib and probably with dasatinib is fairly likely to achieve hematologic responses, but the likelihood of cytogenetic response is lower.
A study reported by Dr. Kirk Schultz on behalf of the Children’s Oncology Group (COG) showed that imatinib mesylate could be given safely in combination with chemotherapy in children with Philadelphia-positive ALL. Patients aged 1-21 with Philadelphia-positive ALL who achieved remission with standard COG induction therapy received an intensive multidrug combination chemotherapy regimen, with introduction of imatinib at 340 mg/m2 for 21 days into an increasing number of treatment blocks in successive cohorts of patients. Patients receiving imatinib had a higher incidence of transaminase elevation in first consolidation and maintenance. However, there were few significant additional increased toxicities compared with historical and contemporaneous controls not receiving imatinib. This appeared to be a feasible combination of a targeted therapy with chemotherapy and will be explored further in subsequent trials.
Dr. Deborah Thomas, a pioneer in the use of imatinib mesylate and chemotherapy in adults with Philadelphia-positive ALL, presented her most recent data at ASH 2007. This is the Phase II Pilot Study of Intensified Chemotherapy With or Without Allogeneic Hematopoietic Stem Cell Transplantation in Children With Very High-Risk Acute Lymphoblastic Leukemia. The chemotherapy backbone was the MD Anderson standard of hyper-CVAD, which is fractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone alternating with high-dose methotrexate and high-dose ara-C. Although a high rate of remission was achieved historically with the use of this regimen in patients with Philadelphia-positive ALL, disease-free survival was brief. Dr. Thomas and colleagues added imatinib at 400 mg per day on days 1 through 14 to each of 8 courses followed by 12 months of imatinib. In later iterations of her work, imatinib was increased to 600 mg per day on days 1 through 14 for courses 1 through 8, with imatinib being given indefinitely after maintenance was completed. Overall, 52 patients with imatinib-naive or minimally treated Philadelphia-positive ALL received therapy from April 2001 to July 2006. With a 3-year treatment follow-up, there were only 7 relapses (14%); however, 12 patients died. The 3-year remission and disease-free survival rates for the combination compared favorably with hyper-CVAD alone (83% vs 24%, and 55% vs 14%, respectively).
- Schultz KR, Aledo A, Bowman WP, et al. Minimal toxicity of imatinib mesylate in combination with intensive chemotherapy for Philadelphia chromosome positive (Ph+) acute lymphoblastic leukemia (ALL) in children: a report of the Children’s Oncology Group (COG) AALL0031 protocol for very high risk ALL. Blood. 2006;108:87a. Abstract 283.
- Thomas DA, Faderl S, Cortes J, et al. Treatment of Philadelphia chromosome-positive acute lymphocytic leukemia with hyper-CVAD and imatinib mesylate. Blood. 2004;103:4396-4407
- Oliver G. Ottmann andBarbara WassmannTreatment of Philadelphia Chromosome–Positive Acute Lymphoblastic Leukemia ASH Hematology 2005© 2005 The American Society of Hematology