303 research outputs found
Implications of BCR-ABL1 kinase domain-mediated resistance in chronic myeloid leukemia
No full textPatients with chronic myeloid leukemia develop resistance to both first-generation and second-generation tyrosine kinase inhibitors (TKIs) as a result of mutations in the kinase domain (KD) of BCR-ABL1. A wide range of BCR-ABL1 KD mutations that confer resistance to TKIs have been identified, and the T315I mutant has proven particularly difficult to target. This review summarizes the prevalence, impact, and prognostic implications of BCR-ABL1 KD mutations in patients with chronic myeloid leukemia who are treated with current TKIs and provides an overview of recent treatment guidelines and future trends for the detection of mutations.Simona Soverini, Susan Branford, Franck E. Nicolini, Moshe Talpaz, Michael W.N. Deininger, Giovanni Martinelli, Martin C. Müller, Jerald P. Radich, Neil P. Sha
Receptors for hematopoietic regulatory cytokines: Overview of structure and function
No full textThe production of blood cells is regulated by the action of external factors, cytokines, that can be released by many cell types. In the first place, a population of multipotent stem cells, mostly in the resting Go phase of the cell cycle, but with self-renewal capacity, gives rise to progenitor cells that are predetermined for differentiation into all kinds of blood cells. Expression of genes for cytokine receptors leads to external regulation of hematopoiesis by cytokines which bind to the receptors, resulting in modifications of proliferation and differentiation, as cytokines are not only growth factors, but are also maturation factors capable of directing hematopoiesis towards functionally competent cells. What is more, they are survival factors capable of suppressing programmed cell death (apoptosis). This is of particular importance for the viability of stem cells which must be preserved. Thus cytokines can act at all positions of the hematopoietic family tree, and the response can differ from proliferation and differentiation of progenitor cells to functional activation of mature cells. Under physiological conditions, during constitutive hematopoiesis, the regulatory cytokines are produced locally, for instance by stromal ceils of the microenvironment, and act locally in a paracrine manner [2]
Compound mutations in BCR-ABL1 are not major drivers of primary or secondary resistance to ponatinib in CP-CML patients
No full textBCR-ABL1 kinase domain mutations can confer resistance to first- and second-generation tyrosine kinase inhibitors (TKIs) in chronic myeloid leukemia (CML). In preclinical studies, clinically achievable concentrations of the third-generation BCR-ABL1 TKI ponatinib inhibit T315I and all other single BCR-ABL1 mutants except T315M, which generates a single amino acid exchange, but requires 2 sequential nucleotide exchanges. In addition, certain compound mutants (containing ≥2 mutations in cis) confer resistance. Initial analyses based largely on conventional Sanger sequencing (SS) have suggested that the preclinical relationship between BCR-ABL1 mutation status and ponatinib efficacy is generally recapitulated in patients receiving therapy. Thus far, however, such analyses have been limited by the inability of SS to definitively identify compound mutations or mutations representing less than ~20% of total alleles (referred to as "low-level mutations"), as well as limited patient follow-up. Here we used next-generation sequencing (NGS) to define the baseline BCR-ABL1 mutation status of 267 heavily pretreated chronic phase (CP)-CML patients from the PACE trial, and used SS to identify clonally dominant mutants that may have developed on ponatinib therapy (30.1 months median follow-up). Durable cytogenetic and molecular responses were observed irrespective of baseline mutation status and included patients with compound mutations. No single or compound mutation was identified that consistently conferred primary and/or secondary resistance to ponatinib in CP-CML patients. Ponatinib is effective in CP-CML irrespective of baseline mutation status.Michael W. Deininger, J. Graeme Hodgson, Neil P. Shah, Jorge E. Cortes, Dong-Wook Kim, Franck E. Nicolini, Moshe Talpaz, Michele Baccarani, Martin C. Müller, Jin Li, Wendy T. Parker, Stephanie Lustgarten, Tim Clackson, Frank G. Haluska, Francois Guilhot, Hagop M. Kantarjian, Simona Soverini, Andreas Hochhaus, Timothy P. Hughes, Victor M. Rivera and Susan Branfor
Mechanisms of resistance to tyrosine kinase inhibitors in chronic myeloid leukemia and recent therapeutic strategies to overcome resistance
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