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  • 1
    Publication Date: 2018-06-02
    Description: Purpose: Glioblastoma is the most aggressive primary brain tumor in adults with a median survival of 15–20 months. Numerous approaches and novel therapeutics for treating glioblastoma have been investigated in the setting of phase III clinical trials, including a recent analysis of the immune checkpoint inhibitor, nivolumab (anti-PD-1), which failed to improve recurrent glioblastoma patient survival. However, rather than abandoning immune checkpoint inhibitor treatment for glioblastoma, which has shown promise in other types of cancer, ongoing studies are currently evaluating this therapeutic class when combined with other agents. Experimental Design: Here, we investigated immunocompetent orthotopic mouse models of glioblastoma treated with the potent CNS-penetrating IDO1 enzyme inhibitor, BGB-5777, combined with anti-PD1 mAb, as well as radiotherapy, based on our recent observation that tumor-infiltrating T cells directly increase immunosuppressive IDO1 levels in human glioblastoma, the previously described reinvigoration of immune cell functions after PD-1 blockade, as well as the proinflammatory effects of radiation. Results: Our results demonstrate a durable survival benefit from this novel three-agent treatment, but not for any single- or dual-agent combination. Unexpectedly, treatment efficacy required IDO1 enzyme inhibition in non-glioblastoma cells, rather than tumor cells. Timing of effector T-cell infiltration, animal subject age, and usage of systemic chemotherapy, all directly impacted therapy-mediated survival benefit. Conclusions: These data highlight a novel and clinically relevant immunotherapeutic approach with associated mechanistic considerations that have formed the basis of a newly initiated phase I/II trial for glioblastoma patients. Clin Cancer Res; 24(11); 2559–73. ©2018 AACR .
    Print ISSN: 1078-0432
    Electronic ISSN: 1557-3265
    Topics: Medicine
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  • 2
    Publication Date: 2018-07-03
    Description: Purpose: The third-generation EGFR tyrosine kinase inhibitor osimertinib is approved to treat patients with EGFR T790M-positive non–small cell lung cancer (NSCLC) who have developed resistance to earlier-generation drugs. Acquired EGFR C797S mutation has been reported to mediate osimertinib resistance in some patients. However, the remaining resistance mechanisms are largely unknown. Experimental Design: We performed mutation profiling using targeted next-generation sequencing (NGS) for 416 cancer-relevant genes on 93 osimertinib-resistant lung cancer patients' samples, mainly cell-free DNAs (cfDNAs), and matched pretreatment samples of 12 patients. In vitro experiments were conducted to functionally study the secondary EGFR mutations identified. Results: EGFR G796/C797, L792, and L718/G719 mutations were identified in 24.7%, 10.8%, and 9.7% of the cases, respectively, with certain mutations coexisting in one patient with different prevalence. L792 and L718 mutants markedly increased the half inhibitory concentration (IC 50 ) of osimertinib in vitro , among which the L718Q mutation conferred the greatest resistance to osimertinib, as well as gefitinib resistance when not coexisting with T790M. Further analysis of the 12 matched pretreatment samples confirmed that these EGFR mutations were acquired during osimertinib treatment. Alterations in parallel or downstream oncogenes such as MET, KRAS , and PIK3CA were also discovered, potentially contributing to the osimertinib-resistance in patients without EGFR secondary mutations. Conclusions: We present comprehensive mutation profiles of a large cohort of osimertinib-resistance lung cancer patients using mainly cfDNA. Besides C797 mutations, novel secondary mutations of EGFR L718 and L792 residues confer osimertinib resistance, both in vitro and in vivo , and are of great clinical and pharmaceutical relevance. Clin Cancer Res; 24(13); 3097–107. ©2018 AACR .
    Print ISSN: 1078-0432
    Electronic ISSN: 1557-3265
    Topics: Medicine
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  • 3
    Publication Date: 2018-07-17
    Description: Purpose: Cluster I pheochromocytomas and paragangliomas (PCPGs) tend to develop malignant transformation, tumor recurrence, and multiplicity. Transcriptomic profiling suggests that cluster I PCPGs and other related tumors exhibit distinctive changes in the tricarboxylic acid (TCA) cycle, the hypoxia signaling pathway, mitochondrial electron transport chain, and methylation status, suggesting that therapeutic regimen might be optimized by targeting these signature molecular pathways. Experimental Design: In the present study, we investigated the molecular signatures in clinical specimens from cluster I PCPGs in comparison with cluster II PCPGs that are related to kinase signaling and often present as benign tumors. Results: We found that cluster I PCPGs develop a dependency to mitochondrial complex I, evidenced by the upregulation of complex I components and enhanced NADH dehydrogenation. Alteration in mitochondrial function resulted in strengthened NAD + metabolism, here considered as a key mechanism of chemoresistance, particularly, of succinate dehydrogenase subunit B ( SDHB )-mutated cluster I PCPGs via the PARP1/BER DNA repair pathway. Combining a PARP inhibitor with temozolomide, a conventional chemotherapeutic agent, not only improved cytotoxicity but also reduced metastatic lesions, with prolonged overall survival of mice with SDHB knockdown PCPG allograft. Conclusions: In summary, our findings provide novel insights into an effective strategy for targeting cluster I PCPGs, especially those with SDHB mutations. Clin Cancer Res; 24(14); 3423–32. ©2018 AACR .
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    Electronic ISSN: 1557-3265
    Topics: Medicine
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  • 4
    Publication Date: 2018-07-17
    Description: Purpose: Ovarian carcinoma no longer responsive to surgery and chemotherapy remains an incurable disease. Alternative therapeutic options remain desperately needed. Patients and Methods: We describe a heavily pretreated patient with ovarian cancer with recurrent disease experiencing a remarkable clinical response to treatment with the anti-PD1 immune checkpoint inhibitor pembrolizumab. The clinical, pathological, and genomic characteristics of this exceptional ovarian cancer responder were carefully investigated using immunohistochemistry (IHC), quantitative multiplex fluorescence methods (i.e., automated quantitative analysis, AQUA) and whole-exome sequencing (WES) techniques. Results: The patient harbored a recurrent/metastatic radiation and chemotherapy-resistant high-grade ovarian carcinoma with clear cell features. While progressing on any standard treatment modality, she demonstrated a remarkable complete response to the anti-PD1 immune checkpoint inhibitor pembrolizumab. WES results were notable for the presence a relative low number of mutations (tumor mutation load/Mb = 4.31, total mutations = 164) and a peculiar structural variant disrupting the 3' region of the PD-L1 gene causing aberrant PD-L1 surface expression as confirmed by IHC and AQUA technology. Heavy infiltration of the PD-L1–mutated and PD-L1–overexpressing tumor with T-cell lymphocytes (i.e., CD4 + /CD8 + TIL), CD68 + macrophages, and CD20 + B cells was detected in the surgical specimen strongly suggesting immune evasion as a key mechanism of tumor growth and survival. Patient's complete clinical responses remain unchanged at the time of the writing of this report with no significant side effects reported to date. Conclusions: Anti-PD1 inhibitors may represent a novel treatment option for recurrent/metastatic human tumors refractory to salvage treatment harboring PD-L1 gene structural variations causing aberrant PD-L1 expression. Clin Cancer Res; 24(14); 3282–91. ©2018 AACR . See related commentary by Lheureux, p. 3233
    Print ISSN: 1078-0432
    Electronic ISSN: 1557-3265
    Topics: Medicine
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  • 5
    Publication Date: 2018-10-02
    Description: TRC105 is an anti-endoglin antibody currently being tested in combination with VEGF inhibitors. In the phase Ib trial, 38 patients were treated with both TRC105 and bevacizumab (BEV), and improved clinical outcomes were observed, despite the fact that 30 patients (79%) were refractory to prior anti-VEGF therapy. Plasma samples were tested for angiogenic and inflammatory biomarkers at baseline and on-treatment. To provide broader context of this combination biomarker study, direct cross-study comparisons were made to biomarker studies previously conducted in patients treated with either BEV or TRC105 monotherapy. Upon treatment with BEV and TRC105, pharmacodynamic changes in response to both BEV (PlGF increase) and TRC105 (soluble endoglin increase) were noted. In addition, distinct patterns of change were identified (similar, opposing, neutralizing). Similar patterns were observed when the combination elicited similar effects to those observed with monotherapy treatment (i.e., decreases of Ang-2, increases of IL6 and VCAM-1). Opposing patterns were observed when the combination led to opposing effects compared with monotherapy treatment (i.e., TGFβ1, PDGF-AA and PDGF-BB, PAI-1). Lastly, neutralizing patterns were observed when one drug led to increase, whereas the other drug led to decrease, and the combination elicited no overall effect on the marker (i.e., VEGF-A, VEGF-D, and IGFBP-3). Patients achieving partial responses or stable disease from the combination exhibited significantly lower expression of E-Cadherin, HGF, ICAM-1, and TSP-2 at baseline. Taken together, the novel biomarker modulations identified may deepen our understanding of the underlying biology in patients treated with BEV and TRC105 compared with either drug alone. Mol Cancer Ther; 17(10); 2248–56. ©2018 AACR .
    Print ISSN: 1535-7163
    Electronic ISSN: 1538-8514
    Topics: Medicine
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  • 6
    Publication Date: 2018-10-02
    Description: Purpose: Despite the challenge to directly target mutant KRAS due to its high GTP affinity, some agents are under development against downstream signaling pathways, such as MEK inhibitors. However, it remains controversial whether MEK inhibitors can boost current chemotherapy in KRAS -mutant lung tumors in clinic. Considering the genomic heterogeneity among patients with lung cancer, it is valuable to test potential therapeutics in KRAS mutation–driven mouse models. Experimental Design: We first compared the pERK1/2 level in lung cancer samples with different KRAS substitutions and generated a new genetically engineered mouse model whose tumor was driven by KRAS G12C , the most common KRAS mutation in lung cancer. Next, we evaluated the efficacy of selumetinib or its combination with chemotherapy, in KRAS G12C tumors compared with KRAS G12D tumors. Moreover, we generated KRAS G12C /p53 R270H model to explore the role of a dominant negative p53 mutation detected in patients in responsiveness to MEK inhibition. Results: We determined higher pERK1/2 in KRAS G12C lung tumors compared with KRAS G12D . Using mouse models, we further identified that KRAS G12C tumors are significantly more sensitive to selumetinib compared with Kras G12D tumors. MEK inhibition significantly increased chemotherapeutic efficacy and progression-free survival of KRAS G12C mice. Interestingly, p53 co-mutation rendered KRAS G12C lung tumors less sensitive to combination treatment with selumetinib and chemotherapy. Conclusions: Our data demonstrate that unique KRAS mutations and concurrent mutations in tumor-suppressor genes are important factors for lung tumor responses to MEK inhibitor. Our preclinical study supports further clinical evaluation of combined MEK inhibition and chemotherapy for lung cancer patients harboring KRAS G12C and wild-type p53 status. Clin Cancer Res; 24(19); 4854–64. ©2018 AACR .
    Print ISSN: 1078-0432
    Electronic ISSN: 1557-3265
    Topics: Medicine
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  • 7
    Publication Date: 2018-10-03
    Description: The development of small-molecule tyrosine kinase inhibitors (TKI) specific for epidermal growth factor receptors (EGFR) with activating mutations has led to a new paradigm in the treatment of non–small cell lung cancer (NSCLC) patients. However, most patients eventually develop resistance. Hypoxia is a key microenvironmental stress in solid tumors that is associated with poor prognosis due, in part, to acquired resistance to conventional therapy. This study documents that long-term, moderate hypoxia promotes resistance to the EGFR TKI, gefitinib, in the NSCLC cell line HCC827, which harbors an activating EGFR mutation. Following hypoxic growth conditions, HCC827 cells treated with gefitinib upregulated N-cadherin, fibronectin, and vimentin expression and downregulated E-cadherin, characteristic of an epithelial-mesenchymal transition (EMT), which prior studies have linked to EGFR TKI resistance. Mechanistically, knockdown of the histone demethylases, LSD1 and PLU-1, prevented and reversed hypoxia-induced gefitinib resistance, with inhibition of the associated EMT, suggesting that LSD1 and PLU-1 play key roles in hypoxia-induced gefitinib resistance and EMT. Moreover, hypoxia-treated HCC827 cells demonstrated more aggressive tumor growth in vivo compared with cells grown in normoxia, but inhibition of LSD1 function by shRNA-mediated knockdown or by the small-molecular inhibitor SP2509 suppressed tumor growth and enhanced gefitinib response in vivo . These results suggest that hypoxia is a driving force for acquired resistance to EGFR TKIs through epigenetic change and coordination of EMT in NSCLC. This study suggests that combination of therapy with EGFR TKIs and LSD1 inhibitors may offer an attractive therapeutic strategy for NSCLCs. Mol Cancer Res; 16(10); 1458–69. ©2018 AACR .
    Print ISSN: 1541-7786
    Electronic ISSN: 1557-3125
    Topics: Medicine
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  • 8
    Publication Date: 2018-11-02
    Description: Tumor metastatic relapse is the primary cause for cancer-associated mortality. Metastatic relapse is believed to arise from quantities of tumor cells that are below detectable thresholds, which are able to resist radio/chemotherapy by obtaining a dormant state and hiding in certain organs, i.e., tumor reservoirs. The thymus, a central T-cell immune organ, has been suggested to be a premetastatic tumor reservoir for B-lymphoma cells. However, it remains unknown whether the thymus is able to harbor nonlymphoid solid tumor cells, and whether chemotherapy can thoroughly eliminate cancer cells in the thymus. If chemotherapy is not able to eliminate these cells in the thymus, then what processes allow for this? Melanoma cell–inoculated and genotoxic doxorubicin-treated mouse model systems were used to determine that the thymus, particularly the atrophied thymus, was able to harbor blood stream–circulating melanoma cells. In addition, a chemotherapy-induced DNA-damage response triggered p53 activation in nonmalignant thymic cells, which in turn resulted in thymocyte death and thymic epithelial cell senescence to develop an inflammatory thymic microenvironment. This inflammatory condition induced thymic-harbored minimal tumor cells to acquire a chemoresistant state. Implications: Here, the thymus serves as a premetastatic reservoir for nonlymphoid solid tumor cells during chemotherapy, which could be a novel target of minimal residual disease in antitumor therapy, thus preventing tumor metastatic relapse. Mol Cancer Res; 16(11); 1652–64. ©2018 AACR .
    Print ISSN: 1541-7786
    Electronic ISSN: 1557-3125
    Topics: Medicine
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  • 9
    Publication Date: 2018-12-11
    Description: Women are increasingly using botanical dietary supplements (BDS) to reduce menopausal hot flashes. Although licorice ( Glycyrrhiza sp.) is one of the frequently used ingredients in BDS, the exact plant species is often not identified. We previously showed that in breast epithelial cells (MCF-10A), Glycyrrhiza glabra (GG) and G. inflata (GI), and their compounds differentially modulated P450 1A1 and P450 1B1 gene expression, which are responsible for estrogen detoxification and genotoxicity, respectively. GG and isoliquiritigenin (LigC) increased CYP1A1 , whereas GI and its marker compound, licochalcone A (LicA), decreased CYP1A1 and CYP1B1 . The objective of this study was to determine the distribution of the bioactive licorice compounds, the metabolism of LicA, and whether GG, GI, and/or pure LicA modulate NAD(P)H quinone oxidoreductase (NQO1) in an ACI rat model. In addition, the effect of licorice extracts and compounds on biomarkers of estrogen chemoprevention ( CYP1A1 ) as well as carcinogenesis ( CYP1B1 ) was studied. LicA was extensively glucuronidated and formed GSH adducts; however, free LicA as well as LigC were bioavailable in target tissues after oral intake of licorice extracts. GG, GI, and LicA caused induction of NQO1 activity in the liver. In mammary tissue, GI increased CYP1A1 and decreased CYP1B1 , whereas GG only increased CYP1A1 . LigC may have contributed to the upregulation of CYP1A1 after GG and GI administration. In contrast, LicA was responsible for GI-mediated downregulation of CYP1B1 . These studies highlight the polypharmacologic nature of botanicals and the importance of standardization of licorice BDS to specific Glycyrrhiza species and to multiple constituents.
    Print ISSN: 1940-6207
    Electronic ISSN: 1940-6215
    Topics: Medicine
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  • 10
    Publication Date: 2018-12-11
    Description: Risk prediction models that estimate an individual's risk of developing colon cancer could be used for a variety of clinical and public health interventions, including offering high-risk individuals enhanced screening or lifestyle interventions. However, if risk prediction models are to be translated into actual clinical and public health practice, they must not only be valid and reliable, but also be easy to use. One way of accomplishing this might be to simplify the information that users of risk prediction tools have to enter, but it is critical to ensure no resulting detrimental effects on model performance. We compared the performance of a simplified, largely categorized exposure-based colon cancer risk model against a more complex, largely continuous exposure-based risk model using two prospective cohorts. Using data from the Nurses’ Health Study and the Health Professionals Follow-up Study we included 816 incident colon cancer cases in women and 412 in men. The discrimination of models was not significantly different comparing a categorized risk prediction model with a continuous prediction model in women (c-statistic 0.600 vs. 0.609, P diff = 0.07) and men (c-statistic 0.622 vs. 0.618, P diff = 0.60). Both models had good calibration in men [observed case count/expected case count (O/E) = 1.05, P 〉 0.05] but not in women (O/E = 1.19, P 〈 0.01). Risk reclassification was slightly improved using categorized predictors in men [net reclassification index (NRI) = 0.041] and slightly worsened in women (NRI = –0.065). Categorical assessment of predictor variables may facilitate use of risk assessment tools in the general population without significant loss of performance.
    Print ISSN: 1940-6207
    Electronic ISSN: 1940-6215
    Topics: Medicine
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