Imatinib is highly effective in newly diagnosed, but not in relapsed, Philadelphia chromosome positive acute lymphoblastic leukemia (Ph þ ALL). BCR-ABL tyrosine kinase domain (TKD) mutations are associated with acquired imatinib resistance, but their role in primary resistance is uncertain. Using highly sensitive ligation-PCR and denaturing high-performance liquid chromatography (DHPLC), we identified baseline TKD mutations in 21% and 42% of imatinib-naïve patients with newly diagnosed (n ¼ 26) or recurrent (n ¼ 65) Ph þ ALL, respectively (P ¼ ns). Within 4 weeks of starting the imatinib treatment, absolute levels of mutant bcr-abl transcripts increased significantly in patients with advanced, but not with de novo, Ph þ ALL. The net expansion of pre-existing mutant clones during imatinib treatment resulted in the rapid appearance of initially undetectable TKD mutations, which after 4 weeks were detectable in 70% of patients with advanced disease. There was a high degree of concordance between the type of mutations detected at relapse and during initial imatinib treatment. The profoundly different outgrowth dynamics of leukemic clones with bcr-abl mutations in imatinib-treated patients who differ in their disease history, provides clinical --translational evidence for a contributory role of non-mutational resistance mechanisms, possibly induced by prior chemotherapy. Moreover, the prevalence of pre-existing, clinically relevant TKD may have been underestimated in tyrosine kinase inhibitor-naïve patients with Ph þ ALL.

These data suggest that although pretreatment with IM is not an independent negative prognostic factor, it cannot improve the dismal prognosis of CML patients at high risk for transplant-related mortality.

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The diagnosis of leptomeningeal dissemination of chronic lymphatic leukemia (CLL) by conventional cytology is unreliable because cytomorphologic criteria of malignancy are often lacking. Immunophenotyping of leukocyte differentiation antigens may also be of limited diagnostic value due to the small number of cells in cerebrospinal fluid (CSF) samples. Molecular methods may support the specific diagnosis of leptomeningeal infiltration of CLL. We present an 54 old patient who was diagnosed with CLL five years ago. Despite clinical signs of leptomeningeal involvement neither magnetic resonance imaging (MRI) nor conventional CSF analysis were suggestive of lymphomatous meningitis. Using PCR we selectively amplified the highly variable and clone-specific CDR3 region of the locus encoding the immunoglobulin heavy chain (IgH) in DNA obtained from both CSF and peripheral blood cells. Analysis of PCR products by high resolution gel electrophoresis revealed a single DNA fragment respectively indicating the presence of a monoclonal cell population in both compartments. DNA sequence analysis of the amplified CDR3 segments confirmed the clonal identity of cells and the leptomeningeal dissemination of CLL.

Autologous hematopoietic stem cells (HSCs) harvested as back-up prior to allogeneic hematopoietic SCT (HSCT) may potentially be useful in the treatment of graft failure or in cases with severe GVHD. Here, we studied the general policies and indications for autologous back-up harvest among the European Group for Blood and Marrow Transplantation centers in the year 2003. The outcome of patients receiving autologous back-up transfusion between 1998 and 2002 was evaluated retrospectively. The responses from 94 centers showed that 48 centers had a general policy with variable indications for autologous back-up harvest. Thirty-five patients with graft failure (25), GVHD (8) or relapse (2) retransplanted with autologous back-ups were reported. Autologous back-up transfusion was performed at a median of 35 days (patients with graft failure) or 90 days (patients with GVHD) after allogeneic HSCT. Within 100 days after autologous HSCT, 21 patients died from treatmentrelated complications (19) or relapse (2). Estimated overall survival at 1 year was 16% (95% CI 0-32%) for patients treated for graft failure and 13% (95% CI 0-37%) for GVHD patients. In conclusion, our data demonstrate that the indication for autologous back-up harvests is limited and that general storage and use cannot be recommended unless in selected prospective studies.