Treatment of EGFR-mutant lung cancer with erlotinib results in dramatic tumor regression but it is invariably followed by drug resistance. In characterizing early transcriptional changes following drug treatment of mutant EGFR-addicted cells, we identified the stem cell transcriptional regulator SOX2 as being rapidly and specifically induced, both in vitro and in vivo. Suppression of SOX2 sensitizes cells to erlotinib-mediated apoptosis, ultimately decreasing the emergence of acquired resistance, whereas its ectopic expression reduces drug-induced cell death. We show that erlotinib relieves EGFR-dependent suppression of FOXO6, leading to its induction of SOX2, which in turn represses the pro-apoptotic BH3-only genes BIM and BMF. Together, these observations point to a physiological feedback mechanism that attenuates oncogene addiction-mediated cell death associated with the withdrawal of growth factor signaling and may therefore contribute to the development of resistance.
Electronic, personalized clinical decision support tools to optimize glycated hemoglobin (HbA1c) screening are lacking. Current screening guidelines are based on simple, categorical rules developed for populations of patients. Although personalized diabetes risk calculators have been created, none are designed to predict current glycemic status using structured data commonly available in electronic health records (EHRs).The goal of this project was to create a mathematical equation for predicting the probability of current elevations in HbA1c (≥5.7%) among patients with no history of hyperglycemia using readily available variables that will allow integration with EHR systems.The reduced model was compared head-to-head with calculators created by Baan and Griffin. Ten-fold cross-validation was used to calculate the bias-adjusted prediction accuracy of the new model. Statistical analyses were performed in R version 3.2.5 (The R Foundation for Statistical Computing) using the rms (Regression Modeling Strategies) package.The final model to predict an elevated HbA1c based on 22,635 patient records contained the following variables in order from most to least importance according to their impact on the discriminating accuracy of the model: age, body mass index, random glucose, race, serum non-high-density lipoprotein, serum total cholesterol, estimated glomerular filtration rate, and smoking status. The new model achieved a concordance statistic of 0.77 which was statistically significantly better than prior models. The model appeared to be well calibrated according to a plot of the predicted probabilities versus the prevalence of the outcome at different probabilities.The calculator created for predicting the probability of having an elevated HbA1c significantly outperformed the existing calculators. The personalized prediction model presented in this paper could improve the efficiency of HbA1c screening initiatives.
Abstract Von-Hippel Lindau (VHL) disease is a familial genetic syndrome characterized by a germline mutation in the VHL gene. VHL patients develop different tumors, including renal cell carcinomas, pheochromocytomas and hemangioblastomas (HB). HBs are complex tumors located in the central nervous system and are currently the main cause of morbidity and mortality among VHL patients. 60-80% percent of VHL patients will develop multiple, synchronous or metachronous HBs in the Central Nervous System. These tumors can also occur sporadically. HBs are refractory to radiation or current targeted therapies. Surgery is the only treatment modality, but due to their location (brain, cerebellum, spine and retina) surgery may be debilitated or not even feasible at all. Both alleles of the VHL gene were reported as inactivated (mutations and LOH studies) in both VHL-related and sporadic HB, but the cellular component(s) harboring this bi-allelic inactivation are unknown. HBs have a complex histology and unclear cell lineage. They are known to consist of a network of stromal cells, endothelial cells and pericytes. Hematopoetic cells may also be present in some HB tumors. In addition to this cellular complexity, the origin of the tumor cell -“stromal cell” - remains unknown. To gain insight into the biology and therapeutic targets of HB, we established an in vitro model of the disease. Using modifications of a previously described technique (Am J Pathol. 2012;180(2):599-607) we generated cell lines from hemangioblastomas of VHL patients. This approach allows the propagation of diverse cell clones, reflecting the complexity of the tumor microenvironment. The different clones and polyclonal populations were characterized using qRTPCR and immunofluorescence. The molecular and phenotypic analysis of the cell lines will be presented. This resource is fundamental for the study of HB biology and it will allow us to dissect the cellular origin of these tumors. In addition, it may facilitate the development of HB xenografts. Citation Format: Ana Martins Metelo, Elizabeth Lockerman, Fred Barker, Jeffrey Engelman, Othon Iliopoulos. Establishment and analysis of an in vitro model for hemangioblastomas of the central nervous system. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2038. doi:10.1158/1538-7445.AM2014-2038
Crizotinib, an inhibitor of anaplastic lymphoma kinase (ALK), has also recently shown efficacy in the treatment of lung cancers with ROS1 translocations. Resistance to crizotinib developed in a patient with metastatic lung adenocarcinoma harboring a CD74-ROS1 rearrangement who had initially shown a dramatic response to treatment. We performed a biopsy of a resistant tumor and identified an acquired mutation leading to a glycine-to-arginine substitution at codon 2032 in the ROS1 kinase domain. Although this mutation does not lie at the gatekeeper residue, it confers resistance to ROS1 kinase inhibition through steric interference with drug binding. The same resistance mutation was observed at all the metastatic sites that were examined at autopsy, suggesting that this mutation was an early event in the clonal evolution of resistance. (Funded by Pfizer and others; ClinicalTrials.gov number, NCT00585195.).
<p>Supplementary Table S1. Patient characteristics and MAPK pathway reactivating resistance mechanisms of BRAF-mutant CRC patients with clinical acquired resistance to RAF/EGFR or RAF/MEK inhibitor combinations.</p>
<p>Supplementary Figures S1-S7, Table S1. Figure S1 contains the cell survival data and immunoblot data of BaF3-CD74-ROS1 (WT) clones treated with multiple ALK-TKIs. Figure S2 contains the identified ROS1 mutations by ENU mutagenesis. Figure S3 contains the cell survival data and immunoblot data of the recovered Ba/F3-CD74-ROS1 mutant cells treated with crizotinib or ceritinib. Figure S4 contains the IC50 data and immunoblot data of the transformed BaF3 cells with CD74-ROS1 mutantstreated with crizotinib, ceritinib or AP26113. Figure S5 contains the structure of ROS1 kinase domain mapped resistant mutations corresponding to Figure 3D. Figure S6 contains the cell survival data and immunoblot data of the recovered Ba/F3-CD74-ROS1 mutant cells treated with cabozantinib (XL184). Figure S7 contains the IC50 data and immunoblot data of the transformed BaF3 cells with CD74-ROS1 mutants treated with cabozantinib (XL184). Table S1 contains the cell survival data of high throughput inhibitor screening corresponding to Table1.</p>
8053 Background: AR typically develops after 9-12 mos of EGFR TKI therapy among EGFR-mutant patients (pts). Here we report a unique series of 42 EGFR mutants who had >1 post-resistant biopsy (bx) that illustrates the heterogeneity of AR within individual pts. Methods: We analyzed prospective data from 126 EGFR mutants with advanced NSCLC who had ≥1 bx after AR developed on EGFR TKI therapy. All biopsies underwent multiplexed CLIA-certified SNaPshot genotyping. Some pts consented to provide tissue for patient-derived cell-line (PDCL) establishment. 42 pts had >1 post-AR bx. We collected data on EGFR TKI therapy, mechanisms of AR observed over multiple biopsies, bx safety and correlations between clinical and PDCL data. Results: Among 42 pts with multiple post-AR biopsies, median age= 57 (range 39-88), 73% were female, 62% had EGFR exon 19 deletion and 31% had L858R. The median number of post-AR biopsies was 2 (range 2-5). While the original EGFR mutation was uniformly maintained, we observed variation in AR mechanisms among 20/42 pts, with changes in T790M status over time in 10 pts. Notably, both gain and loss of T790M were observed on serial biopsies, without a clear correlation to the timing of EGFR TKI therapy or bx site. Changes in histology (8), development of EMT (1) and EGFR amp (1) were also seen. 22/42 pts had no variations in detected mechanisms of AR on serial biopsies, including T790M (n=11), MET amp (2), EGFR amp (1), both MET and EGFR amp (1), SCLC transformation (1), BRAF mutation (1), and no AR mechanism identified (5). Repeat biopsies were safe, with 2.4% bx-related complications and no serious complications. Conclusions: We observed frequent and unexpected changes in the mechanism of AR, particularly T790M status, in pts undergoing serial biopsies, suggesting heterogeneity of resistant clones in these pts. Among pts with T790M, 48% gained or lost the mutation over time. Relationship of AR mechanisms to therapy at the time of bx, bx location and correlations with PDCL data to understand their biologic implications will be presented. Our data suggest serial biopsies in EGFR pts are informative and safe, and may become increasingly important as T790M-specific TKIs become available.
