Successful autologous stem cell collection in patients with chronic myeloid leukemia in complete cytogenetic response, with quantitative measurement of BCR-ABL expression in blood, marrow, and apheresis products

Chronic myelogenous leukemia: role of stem cell transplant in the imatinib era

In the pre-tyrosine kinase (TKI) era, allogeneic stem cell transplant (allo-SCT) was the front-line treatment of choice for young patients with chronic myelogenous leukemia (CML). Today, imatinib is well established as front-line therapy for CML, with excellent long-term outcomes. This has changed the role of allo-SCT and the number of patients undergoing allo-SCT has declined dramatically. Allo-SCT is currently recommended for patients in accelerated/blast phase disease, those who have failed a second-generation TKI and those with TKI-resistant mutations such as T315I. The role of allo-SCT in the management of CML will require continual reappraisal as medical therapies continue to evolve.

Current status of stem cell mobilization

New advances in effective mobilization of peripheral blood stem cells have permitted a greater proportion of patients to benefit from autologous stem cell transplantation. In this review, the relative merits of peripheral blood and mobilized bone marrow are discussed. All available agents are reviewed. A critical assessment of the appropriate dosing and frequency of available growth factors is undertaken, and the most commonly used chemotherapy plus growth factor combinations are covered. Specific recommendations for patients who are poor mobilizers are dealt with including the role of plerixafor.

Hematopoietic progenitor cell collection in patients with chronic myelogenous leukemia in complete cytogenetic remission after imatinib mesylate therapy

The introduction of BCR-ABL tyrosine kinase inhibitors such as imatinib has changed the treatment of chronic myelogenous leukemia (CML). More than 75% of patients achieve complete cytogenetic remission (CCR) after treatment with imatinib, which provides an opportunity to collect minimally involved hematopoietic progenitor stem cell (HPC) products. In order to assess the feasibility of HPC collection in patients with CML, we prospectively enrolled 24 patients who achieved CCR on therapy with imatinib. Two patients could not undergo HPC collection because of coagulopathy. A CD34+ cell yield of > or =2.0 x 10(6)/kg body weight was obtained in 16/22 (73%) patients. Patients who stopped imatinib for at least 3 weeks prior to HPC collection had significantly higher CD34+ cell yields (median: 6.52 x 10(6)/kg body weight) when compared with patients who continued imatinib through the collection (median: 3.74 x 10(6)/kg body weight). Mobilization with granulocyte colony-stimulating factor (G-CSF) did not increase the levels of BCR-ABL transcript. With a mean follow-up of 46 months, all patients but one were in CCR. In conclusion, a significant number of CD34+ cells can be safely collected in patients with CML who are on imatinib therapy, but CD34+ cell yields improve when imatinib is temporarily withheld.