RESUMEN
BACKGROUND: Bullying is common among young students, and cyberbullying has increased due to the use of technology. This study investigates the prevalence of bullying and cyberbullying among high school students and the emotional effects of bullying on students. METHODS: Students at East Chapel Hill High School, Chapel Hill, North Carolina completed the Gatehouse Bullying Scale and the Peer Relations Questionnaire. They answered questions regarding how often they had experienced certain types of bullying in school and the emotional effects the bullying had on them. RESULTS: The combined results from both surveys indicated that the prevalence of bullying was 55% with 18% of respondents reporting cyberbullying. Teasing and name-calling were the most common types of bullying, as 40% of students reported having been teased or called names. The most serious type of bullying, being threatened with harm, hit, or kicked, occurred in 20% of boys and 8% of girls, with 25% of respondents reported "quite upset" by the experience. The majority (79%) of students who had been bullied did not share with anyone about being bullied, and of those who did, only 50% were taken seriously. CONCLUSIONS: Bullying is still prevalent among high school students, and cyberbullying is becoming more widespread. Most victims do not share their bullying experience, and if they did, only half believe they are taken seriously. Both bullying among students in school and cyberbullying deserve attention due to their potentially devastating effects on victims.
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Conducta del Adolescente , Acoso Escolar , Internet , Adolescente , Agresión , Comunicación , Femenino , Humanos , Relaciones Interpersonales , Masculino , North Carolina/epidemiología , Prevalencia , Estudiantes/psicología , Estudiantes/estadística & datos numéricos , Violencia/psicología , Violencia/estadística & datos numéricosRESUMEN
Objective: To evaluate rates of and outcomes associated with antibiotic overuse at hospital discharge for patients with common infectious diseases states. Design: Single-center, respective cohort study. Setting: A large, academic medical center in the Midwest United States. Patients: Adult patients who received antibiotics for community-acquired pneumonia (CAP), uncomplicated cystitis, or mild, non-purulent cellulitis. Patients were excluded if they did not receive antibiotic(s) upon hospital discharge, were pregnant, severely immunocompromised, had concomitant infections, died during hospitalization, or were transferred to another hospital or to an intensive care unit. Methods: Data were abstracted from the electronic medical record of ambulatory antibiotic orders for included patients based on inpatient encounters from August 1, 2021 through July 31, 2022. Results: Of the 182 patients included in the study, antibiotic overuse was common for all three infectious disease states: CAP (n = 87/125, 69.6%), uncomplicated cystitis (n = 21/28, 75.0%), mild, non-purulent cellulitis (n = 28/29, 96.6%). The prevailing reason for overuse was excessive antibiotic duration (n = 127/182, 69.8%; mean antibiotic duration 5.39 vs. 8.32 days, p = 0.001). Antibiotic overuse was associated with approximately one additional day in the hospital (2.48 vs. 3.32 days, p = 0.001), and an increase in emergency department visits within 30 days after discharge (1 vs. 31, p = 0.001) compared to patients without antibiotic overuse at discharge. Conclusion: Antibiotic overuse was prevalent upon hospital discharge for these three common infectious disease states. Transitions of care should be prioritized as an area for antimicrobial stewardship intervention.
RESUMEN
Point mutations in the kinase domain of BCR-ABL are the most common mechanism of drug resistance in chronic myeloid leukemia (CML) patients treated with ABL kinase inhibitors, including imatinib. It has also been shown in vitro that mutations outside the kinase domain in the neighboring linker, SH2, SH3, and Cap domains can confer imatinib resistance. In the context of ABL, these domains have an autoinhibitory effect on kinase activity, and mutations in this region can activate the enzyme. To determine the frequency and relevance to resistance of regulatory domain mutations in CML patients on imatinib, we screened for such mutations in a cohort of consecutive CML patients with various levels of response. Regulatory domain mutations were detected in 7 of 98 patients, whereas kinase domain mutations were detected in 29. One mutation (T212R) conferred in vitro tyrosine kinase inhibitor resistance and was associated with relapse, whereas most other mutations did not affect drug sensitivity. Mechanistic studies showed that T212R increased the activity of ABL and BCR-ABL and that T212R-induced resistance may be partially the result of stabilization of an active kinase conformation. Regulatory domain mutations are uncommon but may explain resistance in some patients without mutations in the kinase domain.
Asunto(s)
Antineoplásicos/uso terapéutico , Resistencia a Antineoplásicos , Proteínas de Fusión bcr-abl/genética , Leucemia Mielógena Crónica BCR-ABL Positiva/tratamiento farmacológico , Mutación , Piperazinas/uso terapéutico , Inhibidores de Proteínas Quinasas/uso terapéutico , Pirimidinas/uso terapéutico , Dominios Homologos src , Adulto , Anciano , Anciano de 80 o más Años , Antineoplásicos/farmacología , Benzamidas , Línea Celular , Estudios de Cohortes , Femenino , Proteínas de Fusión bcr-abl/química , Humanos , Mesilato de Imatinib , Leucemia Mielógena Crónica BCR-ABL Positiva/genética , Masculino , Persona de Mediana Edad , Modelos Moleculares , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Quinasas/metabolismo , Adulto JovenRESUMEN
In chronic-phase chronic myeloid leukemia (CML) patients, the lack of a major cytogenetic response (< 36% Ph(+) metaphases) to imatinib within 12 months indicates failure and mandates a change of therapy. To identify biomarkers predictive of imatinib failure, we performed gene expression array profiling of CD34(+) cells from 2 independent cohorts of imatinib-naive chronic-phase CML patients. The learning set consisted of retrospectively selected patients with a complete cytogenetic response or more than 65% Ph(+) metaphases within 12 months of imatinib therapy. Based on analysis of variance P less than .1 and fold difference 1.5 or more, we identified 885 probe sets with differential expression between responders and nonresponders, from which we extracted a 75-probe set minimal signature (classifier) that separated the 2 groups. On application to a prospectively accrued validation set, the classifier correctly predicted 88% of responders and 83% of nonresponders. Bioinformatics analysis and comparison with published studies revealed overlap of classifier genes with CML progression signatures and implicated beta-catenin in their regulation, suggesting that chronic-phase CML patients destined to fail imatinib have more advanced disease than evident by morphologic criteria. Our classifier may allow directing more aggressive therapy upfront to the patients most likely to benefit while sparing good-risk patients from unnecessary toxicity.
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Antígenos CD34/metabolismo , Antineoplásicos/administración & dosificación , Regulación Leucémica de la Expresión Génica/efectos de los fármacos , Leucemia Mielógena Crónica BCR-ABL Positiva/tratamiento farmacológico , Leucemia Mielógena Crónica BCR-ABL Positiva/metabolismo , Proteínas de Neoplasias/biosíntesis , Piperazinas/administración & dosificación , Pirimidinas/administración & dosificación , Adulto , Anciano , Benzamidas , Humanos , Mesilato de Imatinib , Masculino , Persona de Mediana Edad , Cromosoma Filadelfia/efectos de los fármacosRESUMEN
Targeted therapy has vastly improved outcomes in certain types of cancer. Extension of this paradigm across a broad spectrum of malignancies will require an efficient method to determine the molecular vulnerabilities of cancerous cells. Improvements in sequencing technology will soon enable high-throughput sequencing of entire genomes of cancer patients; however, determining the relevance of identified sequence variants will require complementary functional analyses. Here, we report an RNAi-assisted protein target identification (RAPID) technology that individually assesses targeting of each member of the tyrosine kinase gene family. We demonstrate that RAPID screening of primary leukemia cells from 30 patients identifies targets that are critical to survival of the malignant cells from 10 of these individuals. We identify known, activating mutations in JAK2 and K-RAS, as well as patient-specific sensitivity to down-regulation of FLT1, CSF1R, PDGFR, ROR1, EPHA4/5, JAK1/3, LMTK3, LYN, FYN, PTK2B, and N-RAS. We also describe a previously undescribed, somatic, activating mutation in the thrombopoietin receptor that is sensitive to down-stream pharmacologic inhibition. Hence, the RAPID technique can quickly identify molecular vulnerabilities in malignant cells. Combination of this technique with whole-genome sequencing will represent an ideal tool for oncogenic target identification such that specific therapies can be matched with individual patients.
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Leucemia/genética , Leucemia/terapia , Interferencia de ARN , Alelos , Línea Celular Tumoral , Perfilación de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Humanos , Janus Quinasa 2/genética , Janus Quinasa 2/metabolismo , Leucemia/metabolismo , Mutación/genética , Receptores de Trombopoyetina/genética , Factores de Tiempo , Resultado del TratamientoRESUMEN
Chronic early school absence (preschool through third grade) is associated with school failure. The presence of school nurses may lead to fewer absences, and nurse practitioners in school-based health centers (SBHCs) can facilitate a healthier population resulting in improved attendance. Efforts to get students back to school are unexplored in nursing literature. This article describes a nursing intervention to decrease early school absence in two elementary schools K-3 (N = 449) and a Head Start program (N = 130). The Head Start Family Nurse Practitioner (FNP) contacted families of chronically and excessively absent students by telephone, clinic visit at school, or home visit. The aggregate percentage attendance was evaluated by grades (preschool to third grade), schools (Head Start, Elementary Schools 1 and 2), and grades and schools and compared with publicly available school district aggregate data. There were statistically significant increases in attendance from Year 1 to Year 2 at p < .05 at the elementary level but not at the Head Start level. Student demographics, types of contacts, absence reasons (including sick child), and medical diagnoses are described.
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Absentismo , Enfermería de la Familia/métodos , Enfermeras Practicantes , Servicios de Enfermería Escolar/métodos , Instituciones Académicas/estadística & datos numéricos , Estudiantes/psicología , Niño , Enfermedad Crónica , Intervención Educativa Precoz , Femenino , Humanos , Conducta de Enfermedad , Masculino , North Carolina , Derivación y Consulta , Riesgo , Factores de TiempoRESUMEN
In imatinib-treated chronic myeloid leukemia (CML), secondary drug resistance is often caused by mutations in the BCR-ABL kinase domain (KD). As alternative therapies are available for imatinib resistance, early identification of mutations may prevent disease progression. Because most patients are routinely monitored by BCR-ABL quantitative polymerase chain reaction (PCR), it is important to define the optimal increase in BCR-ABL that should trigger mutation testing. Expert panels have provisionally recommended a 10-fold BCR-ABL increase as the trigger for mutation screening, acknowledging the lack of consensus. To address this question, we monitored 150 CML patients by quantitative PCR and DNA sequencing. Thirty-five different mutations were identified in 53 patients, and, during 22.5 months (median) of follow-up after sequencing, mutations were significantly predictive of shorter progression-free survival. An unbiased receiver operating characteristic analysis identified a 2.6-fold increase in BCR-ABL RNA as the optimal cutoff for predicting a concomitant KD mutation, with a sensitivity of 77% (94% if including subsequent samples). The 2.6-fold threshold approximated the analytic precision limit of our PCR assay. In contrast, transcript rise cutoffs of 5-fold or greater had poor diagnostic sensitivity and no significant association with mutations. We conclude that the currently recommended 10-fold threshold to trigger mutation screening is insensitive and not universally applicable.
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Proteínas de Fusión bcr-abl/genética , Leucemia Mielógena Crónica BCR-ABL Positiva/diagnóstico , Leucemia Mielógena Crónica BCR-ABL Positiva/tratamiento farmacológico , Leucemia Mielógena Crónica BCR-ABL Positiva/genética , Mutación , Piperazinas/uso terapéutico , Pirimidinas/uso terapéutico , Adolescente , Adulto , Anciano , Antineoplásicos/uso terapéutico , Benzamidas , Femenino , Proteínas de Fusión bcr-abl/análisis , Proteínas de Fusión bcr-abl/química , Proteínas de Fusión bcr-abl/metabolismo , Regulación Leucémica de la Expresión Génica , Humanos , Mesilato de Imatinib , Masculino , Persona de Mediana Edad , Mutación/fisiología , Fosfotransferasas/química , Fosfotransferasas/genética , Pronóstico , Estructura Terciaria de Proteína/genética , ARN Mensajero/análisis , Estudios Retrospectivos , Regulación hacia Arriba/genética , Adulto JovenRESUMEN
Transforming mutations in NRAS and KRAS are thought to play a causative role in the development of numerous cancers, including myeloid malignancies. Although mutations at amino acids 12, 13, or 61 account for the majority of oncogenic Ras variants, we hypothesized that less frequent mutations at alternate residues may account for disease in some patients with cancer of unexplained genetic etiology. To search for additional, novel RAS mutations, we sequenced all coding exons in NRAS, KRAS, and HRAS in 329 acute myeloid leukemia (AML) patients, 32 chronic myelomonocytic leukemia (CMML) patients, and 96 healthy individuals. We detected 4 "noncanonical" point mutations in 7 patients: N-Ras(G60E), K-Ras(V14I), K-Ras(T74P), and K-Ras(A146T). All 4 Ras mutants exhibited oncogenic properties in comparison with wild-type Ras in biochemical and functional assays. The presence of transforming RAS mutations outside of positions 12, 13, and 61 reveals that alternate mechanisms of transformation by RAS may be overlooked in screens designed to detect only the most common RAS mutations. Our results suggest that RAS mutations may play a greater role in leukemogenesis than currently believed and indicate that high-throughput screening for mutant RAS alleles in cancer should include analysis of the entire RAS coding region.
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Pruebas Genéticas/métodos , Leucemia Mieloide Aguda/genética , Leucemia Mielomonocítica Crónica/genética , Mutación Puntual , Proteínas Proto-Oncogénicas p21(ras)/genética , Animales , Células de la Médula Ósea/citología , Línea Celular , Transformación Celular Neoplásica/genética , Fibroblastos/citología , Humanos , Leucemia Mieloide Aguda/patología , Leucemia Mielomonocítica Crónica/patología , Ratones , Ratones Endogámicos BALB C , Proteínas Proto-Oncogénicas p21(ras)/metabolismo , Transducción de Señal/fisiologíaRESUMEN
BCR-ABL is proposed to impair cell-cycle control by disabling p27, a tumor suppressor that inhibits cyclin-dependent kinases. We show that in cell lines p27 expression is inversely correlated with expression of SKP2, the F-box protein of SCF(SKP2) (SKP1/Cul1/F-box), the E3 ubiquitin ligase that promotes proteasomal degradation of p27. Inhibition of BCR-ABL kinase causes G(1) arrest, down-regulation of SKP2, and accumulation of p27. Ectopic expression of wild-type SKP2, but not a mutant unable to recognize p27, partially rescues cell-cycle progression. A similar regulation pattern is seen in cell lines transformed by FLT3-ITD, JAK2(V617F), and TEL-PDGFRbeta, suggesting that the SKP2/p27 conduit may be a universal target for leukemogenic tyrosine kinases. Mice that received transplants of BCR-ABL-infected SKP2(-/-) marrow developed a myeloproliferative syndrome but survival was significantly prolonged compared with recipients of BCR-ABL-expressing SKP2(+/+) marrow. SKP2(-/-) leukemic cells demonstrated higher levels of nuclear p27 than SKP2(+/+) counterparts, suggesting that the attenuation of leukemogenesis depends on increased p27 expression. Our data identify SKP2 as a crucial mediator of BCR-ABL-induced leukemogenesis and provide the first in vivo evidence that SKP2 promotes oncogenesis. Hence, stabilization of p27 by inhibiting its recognition by SCF(SKP2) may be therapeutically useful.
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Genes abl , Trastornos Mieloproliferativos/genética , Trastornos Mieloproliferativos/metabolismo , Proteínas Quinasas Asociadas a Fase-S/genética , Animales , Secuencia de Bases , Trasplante de Médula Ósea , Ciclo Celular , Línea Celular Tumoral , Inhibidor p27 de las Quinasas Dependientes de la Ciclina/metabolismo , Cartilla de ADN/genética , Proteínas de Fusión bcr-abl , Expresión Génica , Leucemia Mielógena Crónica BCR-ABL Positiva/etiología , Leucemia Mielógena Crónica BCR-ABL Positiva/genética , Leucemia Mielógena Crónica BCR-ABL Positiva/metabolismo , Leucemia Mielógena Crónica BCR-ABL Positiva/patología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Trastornos Mieloproliferativos/etiología , Trastornos Mieloproliferativos/patología , Proteínas Tirosina Quinasas/antagonistas & inhibidores , Proteínas Tirosina Quinasas/metabolismo , Proteínas Quinasas Asociadas a Fase-S/metabolismoRESUMEN
PURPOSE: Imatinib induces a complete cytogenetic response (CCR) in most chronic myeloid leukemia patients in chronic phase. Although CCR is usually durable, a minority of patients relapse. Biomarkers capable of predicting those CCR patients with a higher risk of relapse would improve therapeutic management. EXPERIMENTAL DESIGN: To assess whether changes in BCR-ABL RNA levels are a prognostic biomarker predictive of relapse, we regularly monitored transcript levels [every 3 months (median)] in 90 patients with CCR during 49 months (median) of imatinib therapy. RESULTS: Throughout follow-up, the 20 patients with eventual relapse had higher transcript levels than the durable responders. Major molecular response (MMR; >3-log reduction of BCR-ABL RNA) was attained by 76 patients (12 with subsequent relapse) and was a significant predictor of prolonged relapse-free survival (P = 0.0008). A minimal 0.5-log increase in transcripts (before relapse; experienced by 42 patients, 16 with subsequent relapse) conveyed a significantly shorter relapse-free survival (P = 0.0017). Loss of MMR (transcript increase to <2.5-log reduction, before relapse; experienced by 33 patients, 11 with subsequent relapse) was also predictive of shortened relapse-free survival (P = 0.0003). A complete molecular response (undetectable transcripts by nested PCR) was attained by 28 MMR patients (one with subsequent relapse) and conveyed a significantly prolonged relapse-free survival (P = 0.0052). CONCLUSIONS: In chronic myeloid leukemia patients with an imatinib-induced CCR, a minimal half-log increase in BCR-ABL RNA (including loss of MMR) is a significant risk factor for future relapse. The achievement of a complete molecular response imparts longer progression-free survival than the achievement of an MMR.
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Antineoplásicos/uso terapéutico , Proteínas de Fusión bcr-abl/genética , Leucemia Mielógena Crónica BCR-ABL Positiva/tratamiento farmacológico , Leucemia Mielógena Crónica BCR-ABL Positiva/genética , Leucemia Mielógena Crónica BCR-ABL Positiva/metabolismo , Piperazinas/uso terapéutico , Pirimidinas/uso terapéutico , Adulto , Anciano , Benzamidas , Biomarcadores de Tumor , Citogenética , Análisis Mutacional de ADN , Femenino , Proteínas de Fusión bcr-abl/biosíntesis , Humanos , Mesilato de Imatinib , Cinética , Leucemia Mielógena Crónica BCR-ABL Positiva/mortalidad , Masculino , Persona de Mediana Edad , ARN Neoplásico/metabolismo , Reproducibilidad de los Resultados , Factores de Tiempo , Resultado del TratamientoAsunto(s)
Antineoplásicos/uso terapéutico , Proteínas de Fusión bcr-abl/genética , Mutación , Piperazinas/uso terapéutico , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamiento farmacológico , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Pirimidinas/uso terapéutico , Adolescente , Adulto , Secuencia de Bases , Benzamidas , Niño , Preescolar , Resistencia a Antineoplásicos/genética , Humanos , Mesilato de Imatinib , Lactante , Masculino , Cromosoma Filadelfia , Recurrencia , Adulto JovenRESUMEN
Preadolescence involves cognitive, social, and physiological changes along with changes in the child's environment. During this developmental stage, young adolescents are transitioning into middle school, forming a larger social network, and managing parental expectations for assuming more responsibility for self-care. The impact of these developmental changes on asthma management is not well understood. The purpose of this study was to better understand asthma and asthma management from the perspective of middle school students. A partnership was formed between the university researcher, several school nurses, and a representative of the health department, through the Orange County Asthma Coalition. Funds were secured from the American Lung Association. School nurses helped to identify and recruit 50 middle school students with asthma to participate in focus groups. The focus-group discussions centered on asthma management with implications for intervention development. Analyses sought to identify developmental issues that affect management. Results indicated that the transition to middle school represents a challenge to managing asthma. As compared with the elementary school environment, support structures are broader and more diffuse, physical education is more demanding, and peer pressure is greater. Nevertheless, the desire for greater autonomy and independence in self-care was strong, particularly among eighth graders. Most interventions are designed for either children or adults, without recognizing the important developmental changes that are occurring in preadolescents with implications for asthma management. A school-based intervention in middle school may help students with asthma transition to greater autonomy of care, while easing transition in other domains of life.
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Desarrollo del Adolescente , Asma/terapia , Cooperación del Paciente/psicología , Autocuidado/métodos , Adolescente , Asma/psicología , Niño , Femenino , Grupos Focales , Humanos , Masculino , Autonomía Personal , Calidad de Vida , Instituciones Académicas , EstudiantesRESUMEN
BACKGROUND: A theater-based human immunodeficiency virus (HIV) prevention intervention developed in urban California was piloted with a new partnership in North Carolina. OBJECTIVES: This work describes the experience of translating a complex program with an enhanced partnership approach, barriers and facilitators of implementation in the new setting, and the challenges and benefits of interdisciplinary, collaborative interventions. METHODS: We gathered perspectives of local stakeholders involved in program implementation through process evaluation interviews and focus groups with undergraduates, a college instructor, school district administrators, and high school teachers. RESULTS: Implementing the intervention in a new setting proved feasible and successful; however, misunderstandings arose among stakeholder groups regarding teaching priorities, philosophies, and values, and were a limiting factor in partnership functioning. CONCLUSIONS: Implementing a cross-disciplinary intervention in a new setting is best achieved through a local community-engaged process, with active involvement of relevant stakeholders. We suggest strategies to strengthen community partnerships cooperating in implementation of complex, context-tailored interventions.
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Relaciones Comunidad-Institución , Drama , Infecciones por VIH/prevención & control , Adolescente , California , Empatía , Femenino , Grupos Focales , Humanos , Masculino , North Carolina , Desarrollo de Programa , Evaluación de Programas y Proyectos de Salud , Confianza , Adulto JovenRESUMEN
Despite vast improvements in our understanding of cancer genetics, a large percentage of cancer cases present without knowledge of the causative genetic events. Tyrosine kinases are frequently implicated in the pathogenesis of numerous types of cancer, but identification and validation of tyrosine kinase targets in cancer can be a time-consuming process. We report the establishment of an efficient, functional screening assay using RNAi technology to directly assess and compare the effect of individually targeting each member of the tyrosine kinase family. We demonstrate that siRNA screening can identify tyrosine kinase targets containing activating mutations in Janus kinase (JAK) 3 (A572V) in CMK cells and c-KIT (V560G) in HMC1.1 cells. In addition, this assay identifies targets that do not contain mutations, such as JAK1 and the focal adhesion kinases (FAK), that are crucial to the survival of the cancer cells. This technique, with additional development, might eventually offer the potential to match specific therapies with individual patients based on a functional assay.
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Leucemia Mieloide Aguda/tratamiento farmacológico , Proteínas Tirosina Quinasas/genética , Interferencia de ARN/fisiología , ARN Interferente Pequeño/genética , Anticuerpos Monoclonales/uso terapéutico , Antineoplásicos/uso terapéutico , Línea Celular Tumoral , Biblioteca de Genes , Humanos , Janus Quinasa 1/genética , Janus Quinasa 3/genética , Células K562 , Leucemia Mieloide Aguda/enzimología , Leucemia Mieloide Aguda/genéticaRESUMEN
BMS-354825 (dasatinib) and AMN107 (nilotinib) are potent alternate Abl inhibitors with activity against many imatinib mesylate-resistant BCR-ABL kinase domain (KD) mutants, except T315I. We used N-ethyl-N-nitrosourea (ENU)-exposed Ba/F3-p210(BCR-ABL) cells to compare incidence and types of KD mutants emerging in the presence of imatinib mesylate, dasatinib, and nilotinib, alone and in dual combinations. Although ENU is expected to induce mutations in multiple proteins, resistant clones were almost exclusively BCR-ABL KD mutant at relevant concentrations of nilotinib and dasatinib, consistent with a central role of KD mutations for resistance to these drugs. Twenty different mutations were identified with imatinib mesylate, 10 with nilotinib (including only 1 novel mutation, E292V) and 9 with dasatinib. At intermediate drug levels the spectrum narrowed to F317V and T315I for dasatinib and Y253H, E255V, and T315I for nilotinib. Thus, cross-resistance is limited to T315I, which is also the only mutant isolated at drug concentrations equivalent to maximal achievable plasma trough levels. With drug combinations maximal suppression of resistant clone outgrowth was achieved at lower concentrations compared with single agents, suggesting that such combinations may be equipotent to higher-dose single agents. However, sequencing uniformly revealed T315I, consistent with the need for a T315I inhibitor, to completely block resistance.
Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Etilnitrosourea , Mutágenos , Piperazinas/administración & dosificación , Pirimidinas/administración & dosificación , Tiazoles/administración & dosificación , Benzamidas , Dasatinib , Ensayos de Selección de Medicamentos Antitumorales , Proteínas de Fusión bcr-abl/metabolismo , Humanos , Mesilato de Imatinib , Concentración 50 Inhibidora , Mutación Puntual , Estructura Terciaria de ProteínaRESUMEN
Patients with chronic myeloid leukemia (CML) treated with imatinib in early chronic phase tend to have durable remissions, but there is a high rate of relapse in patients with advanced disease. Mutations in the kinase domain of BCR-ABL that impair drug binding have been identified as the major mechanism of resistance. It is not known when exactly these mutations arise, but in some patients retrospective analysis of pretherapeutic samples demonstrated identical mutations, suggesting selection in the presence of drug. In the present study we have used a highly sensitive PCR assay to screen for kinase domain mutations in pretherapeutic samples from CML patients, irrespective of their subsequent response to imatinib. We find that kinase domain mutations are demonstrable in approximately 1/3 of patients with accelerated phase or blast crisis and that the presence of two copies of the Philadelphia chromosome is strongly correlated with mutation detection. Unexpectedly, kinase domain mutant clones were not invariably selected in the presence of drug, suggesting that additional mechanisms must contribute to a fully drug resistant leukemia.
Asunto(s)
Resistencia a Antineoplásicos/genética , Proteínas de Fusión bcr-abl/genética , Leucemia Mielógena Crónica BCR-ABL Positiva/tratamiento farmacológico , Leucemia Mielógena Crónica BCR-ABL Positiva/genética , Mutación/genética , Fosfotransferasas/genética , Piperazinas/farmacología , Pirimidinas/farmacología , Adulto , Anciano , Anciano de 80 o más Años , Alelos , Benzamidas , Femenino , Proteínas de Fusión bcr-abl/química , Humanos , Mesilato de Imatinib , Masculino , Persona de Mediana Edad , Fenotipo , Piperazinas/uso terapéutico , Reacción en Cadena de la Polimerasa , Estructura Terciaria de Proteína , Pirimidinas/uso terapéutico , ARN Mensajero/genética , ARN Mensajero/metabolismo , Estudios Retrospectivos , Sensibilidad y EspecificidadRESUMEN
Mutations in the kinase domain (KD) of BCR-ABL are the leading cause of acquired imatinib resistance. In some cases, identical mutations were detected at relapse and in pretherapeutic specimens, consistent with selection of resistant clones in the presence of drug. However, the incidence of KD mutations in imatinibnaive patients, irrespective of response to therapy, is unknown. We studied mutation frequency in 66 patients with chronic myelogenous leukemia (CML), using cDNA sequencing and allele-specific oligonucleotide-polymerase chain reaction (ASO-PCR) assays for 8 common mutations. Thirteen patients were positive by ASO-PCR only, 1 by ASO-PCR and sequencing, and 1 by sequencing only (overall frequency, 22.7%). T315I was most frequent (12% of patients). Eleven of the 14 patients with positive ASO-PCR had follow-up samples available for sequencing. Wild-type sequence was detected in 6 of 11, 2 different mutations in 1 of 11, and identical mutations in 4 of 11 patients, 2 of whom had achieved major cytogenetic response. In multivariate analysis mutation detection was associated with clonal cytogenetic evolution, exposure to 6-Thioguanine, and a low platelet count, but not with response to imatinib, event-free survival, and overall survival. KD mutants present at low levels do not invariably lead to relapse, and additional factors are required to induce a fully drug-resistant phenotype.
Asunto(s)
Resistencia a Antineoplásicos/genética , Proteínas de Fusión bcr-abl/genética , Leucemia Mielógena Crónica BCR-ABL Positiva/genética , Mutación , Piperazinas , Pirimidinas , Adulto , Anciano , Anciano de 80 o más Años , Benzamidas , Células Clonales , Análisis Mutacional de ADN , Femenino , Frecuencia de los Genes , Humanos , Mesilato de Imatinib , Cariotipificación , Leucemia Mielógena Crónica BCR-ABL Positiva/tratamiento farmacológico , Leucemia Mielógena Crónica BCR-ABL Positiva/mortalidad , Masculino , Persona de Mediana Edad , Análisis Multivariante , Proteínas Tirosina Quinasas/genética , Factores de Riesgo , Sensibilidad y Especificidad , Resultado del TratamientoRESUMEN
Activating mutations in tyrosine kinases have been identified in hematopoietic and nonhematopoietic malignancies. Recently, we and others identified a single recurrent somatic activating mutation (JAK2V617F) in the Janus kinase 2 (JAK2) tyrosine kinase in the myeloproliferative disorders (MPDs) polycythemia vera, essential thrombocythemia, and myeloid metaplasia with myelofibrosis. We used direct sequence analysis to determine if the JAK2V617F mutation was present in acute myeloid leukemia (AML), chronic myelomonocytic leukemia (CMML)/atypical chronic myelogenous leukemia (aCML), myelodysplastic syndrome (MDS), B-lineage acute lymphoblastic leukemia (ALL), T-cell ALL, and chronic lymphocytic leukemia (CLL). Analysis of 222 patients with AML identified JAK2V617F mutations in 4 patients with AML, 3 of whom had a preceding MPD. JAK2V617F mutations were identified in 9 (7.8%) of 116 CMML/a CML samples, and in 2 (4.2%) of 48 MDS samples. We did not identify the JAK2V617F disease allele in B-lineage ALL (n = 83), T-cell ALL (n = 93), or CLL (n = 45). These data indicate that the JAK2V617F allele is present in acute and chronic myeloid malignancies but not in lymphoid malignancies.
Asunto(s)
Alelos , Leucemia Linfoide/genética , Leucemia Mieloide/genética , Mutación Puntual , Proteínas Tirosina Quinasas/metabolismo , Proteínas Proto-Oncogénicas/metabolismo , Anciano , Sustitución de Aminoácidos , Estudios de Casos y Controles , Activación Enzimática/genética , Femenino , Humanos , Janus Quinasa 2 , Leucemia Linfocítica Crónica de Células B/enzimología , Leucemia Linfocítica Crónica de Células B/genética , Leucemia Linfoide/enzimología , Leucemia Mieloide/enzimología , Leucemia Mielomonocítica Crónica/enzimología , Leucemia Mielomonocítica Crónica/genética , Masculino , Persona de Mediana Edad , Proteínas Tirosina Quinasas/genética , Proteínas Proto-Oncogénicas/genéticaRESUMEN
Imatinib mesylate (Gleevec, formerly STI571) is an effective therapy for all stages of chronic myelogenous leukemia (CML). While responses in chronic-phase CML are generally durable, resistance develops in many patients with advanced disease. We evaluated novel antileukemic agents for their potential to overcome resistance in various imatinib-resistant cell lines. Using cell proliferation assays, we investigated whether different mechanisms of resistance to imatinib would alter the efficacy of arsenic trioxide (As2O3) or 5-aza-2-deoxycytidine (decitabine) alone and in combination with imatinib. Our results indicate that resistance to imatinib induced by Bcr-Abl overexpression or by engineered expression of clinically relevant Bcr-Abl mutants does not induce cross-resistance to As2O3 or decitabine. Combined treatment with these agents and imatinib is beneficial in cell lines that have residual sensitivity to imatinib monotherapy, with synergistic growth inhibition achieved only at doses of imatinib that overcome resistance. In some imatinib-resistant cell lines, combination treatments that use low doses of imatinib lead to antagonism. Apoptosis studies suggest that this can be explained in part by the reduced proapoptotic activity of imatinib in resistant cell lines. These data underline the importance of resistance testing and provide a rational approach for dose-adjusted administration of imatinib when combined with other agents.