Project description:Activating mutations in epidermal growth factor receptor (EGFR) are present in a subset of lung cancers, and predict sensitivity to EGFR tyrosine kinase inhibitors. Acquisition of EGFR T790M is the most common mechanism of resistance to EGFR tyrosine kinase inhibitors and rarely is seen before treatment. Germline EGFR T790M mutations have been reported, although the penetrance and clinical significance of this mutation is unknown. We describe the identification of a patient with an EGFR T790M germline mutation and subsequent germline testing in her unaffected family members. Genetic testing revealed two additional EGFR T790M germline carriers, one of which was subsequently diagnosed with metastatic lung adenocarcinoma.
Project description:IntroductionHereditary lung cancer syndromes are rare, and T790M germline mutations of the epidermal growth factor receptor (EGFR) gene predispose to the development of lung cancer. The goal of this study was to determine the clinical features and smoking status of lung cancer cases and unaffected family members with this germline mutation and to estimate its incidence and penetrance.MethodsWe studied a family with germline T790M mutations over five generations (14 individuals) and combined our observations with data obtained from a literature search (15 individuals).ResultsT790M germline mutations occurred in approximately 1% of non-small-cell lung cancer cases and in less than one in 7500 subjects without lung cancer. Both sporadic and germline T790M mutations were predominantly adenocarcinomas, favored female gender, and were occasionally multifocal. Of lung cancer tumors arising in T790M germline mutation carriers, 73% contained a second activating EGFR gene mutation. Inheritance was dominant. The odds ratio that T790M germline carriers who are smokers will develop lung cancer compared with never smoker carriers was 0.31 (p = 6.0E-05). There was an overrepresentation of never smokers with lung cancer with this mutation compared with the general lung cancer population (p = 7.4E-06).ConclusionGermline T790M mutations result in a unique hereditary lung cancer syndrome that targets never smokers, with a preliminary estimate of 31% risk for lung cancer in never smoker carriers, and this risk may be lower for heavy smokers. The resultant cancers share several features and differences with lung cancers containing sporadic EGFR mutations.
Project description:The role of even the strongest genetic risk factor for Alzheimer's disease (AD), the apolipoprotein E (APOE) ε4 allele, in its etiology remains poorly understood. We examined molecular signatures of AD defined as differences in linkage disequilibrium patterns between AD-affected and -unaffected whites (2673/16,246), Hispanics (392/867), and African Americans (285/1789), separately. We focused on 29 polymorphisms from 5 genes in the APOE region emphasizing beneficial and adverse effects of the APOE ε2- and ε4-coding single-nucleotide polymorphisms, respectively, and the differences in the linkage disequilibrium structures involving these alleles between AD-affected and -unaffected subjects. Susceptibility to AD is likely the result of complex interactions of the ε2 and ε4 alleles with other polymorphisms in the APOE region, and these interactions differ across races/ethnicities corroborating differences in the adverse and beneficial effects of the ε4 and ε2 alleles. Our findings support complex race/ethnicity-specific haplotypes promoting and protecting against AD in this region. They contribute to better understanding of polygenic and resilient mechanisms, which can explain why even homozygous ε4 carriers may not develop AD.
Project description:BackgroundSomatic mutations in the EGFR gene occur in about 50% of non-small cell lung cancers, with the T790M mutation significantly contributing to secondary resistance against EGFR-TKI drugs. However, EGFR T790M germline mutations rarely occur.Case presentationIn this study, we report a case of a lung adenocarcinoma family lineage linked to a germline EGFR T790M mutation. The main subject was diagnosed with stage IV lung adenocarcinoma and experienced a 19-month period without disease progression while treated with Osimertinib. We collected both clinicopathological and familial data from a patient with lung adenocarcinoma. Next-generation sequencing of 40 key genes was performed on the proband's tumor tissue. To detect EGFR germline mutations, Sanger sequencing was conducted on peripheral blood mononuclear cells from the proband and his two daughters. Mutations such as EGFR T790M, EGFR 19-Del, TP53, and PIK3CA were identified in the proband's lung cancer tissue. Additionally, germline EGFR T790M mutations were confirmed in the proband and his daughters through sequencing of their peripheral blood samples. CT scans revealed multiple pulmonary nodules in both daughters.ConclusionsThese observations suggest that germline mutations in EGFR T790M could be strongly linked to a familial predisposition to lung cancer.
Project description:IntroductionA subset of lung adenocarcinomas (ADs) has been found to have somatic activating mutations in the tyrosine kinase domain of the EGFR gene, associated with response to EGFR tyrosine kinase inhibitor therapy. Rare germline mutations within this domain, including EGFR T790M, have been associated with genetic susceptibility to lung ADs. Using high-throughput sequencing, we elucidate the genomic evolution in tissues from a patient with lung AD carrying a germline EGFR T790M mutation.MethodsWe performed microdissection, targeted panel, and whole-exome sequencing to molecularly characterize multiple foci of atypical adenomatous hyperplasia (AAH), in situ and invasive components of AD, normal lung tissue, and whole blood from the patient. Normal lung tissue was analyzed for potential acquired somatic genome alterations ("field effect").ResultsAll lesions harbored a secondary somatic EGFR mutation, either L858R or L861Q, in addition to the germline T790M mutation. Clear overlap was observed between the somatic profiles of in situ and invasive AD components, confirming clonal relatedness. AAH lesions shared few to no somatic alterations with the AD, suggesting clonal independence. No robust evidence of field effect was identified in the normal lung tissue.ConclusionsSomatic EGFR mutations are early events in the pathogenesis of lung ADs arising in the context of germline EGFR T790M. Synchronous AAH lesions seem to be independent. Stepwise genomic evolution is observed in association with invasiveness of the neoplastic cell population.
Project description:The clinical efficacy of epidermal growth factor receptor (EGFR) kinase inhibitors in EGFR-mutant non-small-cell lung cancer (NSCLC) is limited by the development of drug-resistance mutations, including the gatekeeper T790M mutation. Strategies targeting EGFR T790M with irreversible inhibitors have had limited success and are associated with toxicity due to concurrent inhibition of wild-type EGFR. All current EGFR inhibitors possess a structurally related quinazoline-based core scaffold and were identified as ATP-competitive inhibitors of wild-type EGFR. Here we identify a covalent pyrimidine EGFR inhibitor by screening an irreversible kinase inhibitor library specifically against EGFR T790M. These agents are 30- to 100-fold more potent against EGFR T790M, and up to 100-fold less potent against wild-type EGFR, than quinazoline-based EGFR inhibitors in vitro. They are also effective in murine models of lung cancer driven by EGFR T790M. Co-crystallization studies reveal a structural basis for the increased potency and mutant selectivity of these agents. These mutant-selective irreversible EGFR kinase inhibitors may be clinically more effective and better tolerated than quinazoline-based inhibitors. Our findings demonstrate that functional pharmacological screens against clinically important mutant kinases represent a powerful strategy to identify new classes of mutant-selective kinase inhibitors.
Project description:An acquired mutation (T790M) in the epidermal growth factor receptor (EGFR) accounts for half of all relapses in non-small cell lung cancer (NSCLC) patients who initially respond to EGFR kinase inhibitors. In this study, we demonstrated for the first time that EGFR-T790M interacts with the cytoskeletal components, myosin heavy chain 9 (MYH9) and β-actin, in the nucleus of H1975 cells carrying the T790M-mutant EGFR. The interactions of EGFR with MYH9 and β-actin were reduced in the presence of blebbistatin, a specific inhibitor for the MYH9-β-actin interaction, suggesting that the EGFR interaction with MYH9 and β-actin is affected by the integrity of the cytoskeleton. These physical interactions among MYH9, β-actin, and EGFR were also impaired by CL-387,785, a kinase inhibitor for EGFR-T790M. Furthermore, CL-387,785 and blebbistatin interacted in a synergistic fashion to suppress cell proliferation and induce apoptosis in H1975 cells. The combination of CL-387,785 and blebbistatin enhanced the down-regulation of cyclooxygenase-2 (COX-2), a transcriptional target of nuclear EGFR. Overall, our findings demonstrate that disrupting EGFR interactions with the cytoskeletal components enhanced the anti-cancer effects of CL-387,785 against H1975 cells, suggesting a novel therapeutic approach for NSCLC cells that express the drug-resistant EGFR-T790M.
Project description:Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors, gefitinib and erlotinib are effective therapies against mutant non-small cell lung cancers (NSCLCs). Treatment is limited by the development of resistance in part explained by the gain of a secondary EGFR mutation, T790M, at the gatekeeper residue. Irreversible EGFR inhibitors, including PF00299804, are effective in vitro and in vivo against EGFR mutant tumors that contain EGFR T790M and are currently under clinical development. In this study, we generate models of resistance to PF00299804, using cell lines with EGFR T790M and show that the PF00299804-resistant models develop focal amplification of EGFR that preferentially involves the T790M-containing allele. These PF00299804-resistant cell lines remain dependent on EGFR for growth as downregulation of EGFR by shRNA compromises their viability. We show that resistance to PF00299804 arises, at least in part, through selection of a pre-existing EGFR T790M-amplified clone both in vitro and using a xenograft model in vivo. Our findings show that EGFR T790M is a common resistance mechanism to both reversible, and when amplified, the irreversible EGFR kinase inhibitors further emphasizing the need to develop more potent therapies against EGFR T790M. These findings can be used to guide studies of patient tumor specimens from ongoing clinical trials of irreversible EGFR kinase inhibitors.
Project description:ObjectiveThe objective of this study is to examine racial/ethnic differences in prevalence of chronic conditions and multimorbidities in the geriatric population of a state with diverse races/ethnicities.MethodFifteen chronic conditions and their dyads and triads were investigated using Hawaii Medicare 2012 data. For each condition, a multivariable logistic regression model was used to investigate differences in race/ethnicity, adjusting for subject characteristics.ResultsOf the 84,212 beneficiaries, 27.8% were Whites, 54.6% Asians, and 5.2% Hispanics. Racial/ethnic disparities were prevalent for most conditions. Compared with Whites, Asians, Hispanics, and Others showed significantly higher prevalence rates in hypertension, hyperlipidemia, diabetes, and most dyads or triads of the chronic conditions. However, Whites had higher prevalence rates in arthritis and dementia.DiscussionRace/ethnicity may need to be considered when making clinical decisions and developing health care programs to reduce health disparities and improve quality of life for older individuals with chronic conditions.