Response dynamics in chronic-phase chronic myeloid leukemia.

Cytogenetic response (CyR), especially complete CyR (CCyR), has historically and is currently associated with a significant survival advantage in patients with chronic-phase chronic myeloid leukemia (CP-CML). CCyR represents a critical level of disease reduction irrespective of treatment type, and timely achievement demonstrates treatment-sensitive disease. Guidelines from European LeukemiaNet and the National Comprehensive Cancer Network therefore state that alternative therapies should be considered for patients not achieving CCyR by 6 or 12 months.

KIT gene mutations and copy number in melanoma subtypes.

Purpose: We recently identified a KIT exon 11 mutation in an anorectal melanoma of a patient who had an excellent response to treatment with imatinib. To determine the frequency of KIT mutations across melanoma subtypes, we surveyed a large series of tumors.

Experimental Design: One hundred eighty-nine melanomas were screened for mutations in KIT exons 11, 13, and 17.

Transvection mediated by the translocated cyclin D1 locus in mantle cell lymphoma.

In mantle cell lymphoma (MCL) and some cases of multiple myeloma (MM), cyclin D1 expression is deregulated by chromosome translocations involving the immunoglobulin heavy chain (IgH) locus. To evaluate the mechanisms responsible, gene targeting was used to study long-distance gene regulation. Remarkably, these targeted cell lines lost the translocated chromosome (t(11;14)).

Defining and managing imatinib resistance.

While imatinib is highly effective therapy, with improving prospects over time for sustained remission and potential to severely limit or eliminate disease progression and transformation, a minority of patients either fail or respond suboptimally to imatinib; as well, disease eradication may not be possible with imatinib. Distinct patterns of resistance have evolved with the use of imatinib, and Abl kinase mutations, which alter imatinib binding or favor kinase conformations inaccessible to imatinib, are a common finding associated with clinical resistance. Dasatinib and nilotinib, alternate Abl kinase inhibitors, restore hematologic and cytogenetic remission in the majority of patients with primary failure or acquired resistance in chronic phase disease; in advanced disease and Philadelphia chromosome (Ph)(+) ALL, responses are more limited and relapse is common.

Bone marrow-derived cells fuse with normal and transformed intestinal stem cells.

Transplanted adult bone marrow-derived cells (BMDCs) have been shown to adopt the phenotype and function of several nonhematopoietic cell lineages and promote tumorigenesis. Beyond its cancer enhancing potential, cell fusion has recently emerged as an explanation of how BMDCs regenerate diseased heptocytes, contribute to Purkinje neurons and skeletal and cardiac muscle cells, and participate in skin and heart regeneration. Although bone marrow-derived epithelial cells also have been observed in the intestine, fusion as a mechanism has not been investigated.

Stem cell transplantation in patients with chronic myelogenous leukemia: when should it be used?

Hematopoietic stem cell transplantation has been a cornerstone of therapy for chronic myelogenous leukemia (CML) for more than 15 years and is still a standard treatment option for patients with CML. The advent of imatinib mesylate, an inhibitor of the molecular defect driving CML, the BCR-ABL tyrosine kinase, has rewritten treatment algorithms for this disease and has shifted focus away from allografting. Despite advances in stem cell transplantation, such as broader availability with the use of modified conditioning regimens, use of allografting has diminished.

Resistance of prostate cancer cell lines to COX-2 inhibitor treatment.

Targeting of cyclooxygenase-2 (COX-2) for cancer chemoprevention is well supported for several tumor types, most notably colon cancer. In contrast, the data for its role in prostate cancer carcinogenesis are correlative only. Thus, we compared the COX-2 expression, activity, and effects of inhibition in prostate cancer cells on COX-2-dependent colon cancer cells.

Targeted deletion of the chicken beta-globin regulatory elements reveals a cooperative gene silencing activity.

The chicken beta-globin locus represents a well characterized system to study the role of both proximal and distal regulatory elements in a eukaryotic multigene domain. The function of the chicken beta(A)/epsilon-intergenic enhancer and upstream regulatory elements 5'-HS1 and 5'-HS2 were studied using a gene targeting approach in chicken DT40 cells followed by microcell-mediated chromosome transfer into human erythroleukemia cells (K562). These regulatory elements all repressed expression of the rho- and beta(H)-chicken globin genes in the chromosome transfer assay.

Cyclin D1 activation in B-cell malignancy: association with changes in histone acetylation, DNA methylation, and RNA polymerase II binding to both promoter and distal sequences.

Cyclin D1 expression is deregulated by chromosome translocation in mantle cell lymphoma and a subset of multiple myeloma. The molecular mechanisms involved in long-distance gene deregulation remain obscure, although changes in acetylated histones and methylated CpG dinucleotides may be important. The patterns of DNA methylation and histone acetylation were determined at the cyclin D1 locus on chromosome 11q13 in B-cell malignancies.

Divergent clinical outcome in two CML patients who discontinued imatinib therapy after achieving a molecular remission.

Imatinib mesylate therapy leads to major or complete cytogenetic response in the majority of patients with CML in the chronic phase. A subset of these patients also achieves remission at a molecular level. It is not known if such patients will require continuous therapy, or whether imatinib could be safely discontinued.

Transplantation for chronic myelogenous leukemia: yes, no, maybe so. . . An Oregon perspective.

Chronic myelogenous leukemia (CML) is a hematopoietic stem cell disorder in which allogeneic stem cell transplantation remains the only curative option, but its use is limited by donor availability and treatment-related morbidity and mortality. Imatinib mesylate is a targeted agent for CML with efficacy to date, which is superior to all other nontransplant therapy and has limited toxicity. The curative potential of imatinib remains to be proven and may be limited to a small number of patients.

Recent advancements in the treatment of chronic myelogenous leukemia.

Chronic myelogenous leukemia (CML) is a clonal hematopoetic stem cell disorder characterized by the Philadelphia chromosome and resultant production of the constitutively activated Bcr-Abl tyrosine kinase. Characterized clinically by marked myeloid proliferation, it invariably terminates in an acute leukemia. Conventional therapeutic options include interferon-based regimens and stem cell transplantation, with stem cell transplantation being the only curative therapy.