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  • 1
    Publication Date: 2010-11-26
    Description: Activating B-RAF(V600E) (also known as BRAF) kinase mutations occur in approximately 7% of human malignancies and approximately 60% of melanomas. Early clinical experience with a novel class I RAF-selective inhibitor, PLX4032, demonstrated an unprecedented 80% anti-tumour response rate among patients with B-RAF(V600E)-positive melanomas, but acquired drug resistance frequently develops after initial responses. Hypotheses for mechanisms of acquired resistance to B-RAF inhibition include secondary mutations in B-RAF(V600E), MAPK reactivation, and activation of alternative survival pathways. Here we show that acquired resistance to PLX4032 develops by mutually exclusive PDGFRbeta (also known as PDGFRB) upregulation or N-RAS (also known as NRAS) mutations but not through secondary mutations in B-RAF(V600E). We used PLX4032-resistant sub-lines artificially derived from B-RAF(V600E)-positive melanoma cell lines and validated key findings in PLX4032-resistant tumours and tumour-matched, short-term cultures from clinical trial patients. Induction of PDGFRbeta RNA, protein and tyrosine phosphorylation emerged as a dominant feature of acquired PLX4032 resistance in a subset of melanoma sub-lines, patient-derived biopsies and short-term cultures. PDGFRbeta-upregulated tumour cells have low activated RAS levels and, when treated with PLX4032, do not reactivate the MAPK pathway significantly. In another subset, high levels of activated N-RAS resulting from mutations lead to significant MAPK pathway reactivation upon PLX4032 treatment. Knockdown of PDGFRbeta or N-RAS reduced growth of the respective PLX4032-resistant subsets. Overexpression of PDGFRbeta or N-RAS(Q61K) conferred PLX4032 resistance to PLX4032-sensitive parental cell lines. Importantly, MAPK reactivation predicts MEK inhibitor sensitivity. Thus, melanomas escape B-RAF(V600E) targeting not through secondary B-RAF(V600E) mutations but via receptor tyrosine kinase (RTK)-mediated activation of alternative survival pathway(s) or activated RAS-mediated reactivation of the MAPK pathway, suggesting additional therapeutic strategies.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3143360/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3143360/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Nazarian, Ramin -- Shi, Hubing -- Wang, Qi -- Kong, Xiangju -- Koya, Richard C -- Lee, Hane -- Chen, Zugen -- Lee, Mi-Kyung -- Attar, Narsis -- Sazegar, Hooman -- Chodon, Thinle -- Nelson, Stanley F -- McArthur, Grant -- Sosman, Jeffrey A -- Ribas, Antoni -- Lo, Roger S -- K22 CA151638/CA/NCI NIH HHS/ -- K22 CA151638-01/CA/NCI NIH HHS/ -- K24 CA097588/CA/NCI NIH HHS/ -- England -- Nature. 2010 Dec 16;468(7326):973-7. doi: 10.1038/nature09626. Epub 2010 Nov 24.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Dermatology/Department of Medicine, UCLA's Jonsson Comprehensive Cancer Center, 52-121 CHS, Los Angeles, California 90095-1750, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21107323" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Cell Line, Tumor ; *Drug Resistance, Neoplasm/drug effects ; Enzyme Activation/drug effects ; *Gene Expression Regulation, Neoplastic/drug effects ; Genes, ras/*genetics ; Humans ; Indoles/pharmacology/therapeutic use ; MAP Kinase Signaling System/drug effects ; Melanoma/*drug therapy/*enzymology/genetics/pathology ; Mitogen-Activated Protein Kinase Kinases/antagonists & inhibitors ; Mutation/genetics ; Oligonucleotide Array Sequence Analysis ; Protein Kinase Inhibitors/pharmacology/therapeutic use ; Proto-Oncogene Proteins B-raf/*antagonists & ; inhibitors/chemistry/genetics/metabolism ; Receptor Protein-Tyrosine Kinases/*metabolism ; Receptor, Platelet-Derived Growth Factor beta/biosynthesis/genetics ; Sulfonamides/pharmacology/therapeutic use ; Up-Regulation/drug effects
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2010-09-09
    Description: B-RAF is the most frequently mutated protein kinase in human cancers. The finding that oncogenic mutations in BRAF are common in melanoma, followed by the demonstration that these tumours are dependent on the RAF/MEK/ERK pathway, offered hope that inhibition of B-RAF kinase activity could benefit melanoma patients. Herein, we describe the structure-guided discovery of PLX4032 (RG7204), a potent inhibitor of oncogenic B-RAF kinase activity. Preclinical experiments demonstrated that PLX4032 selectively blocked the RAF/MEK/ERK pathway in BRAF mutant cells and caused regression of BRAF mutant xenografts. Toxicology studies confirmed a wide safety margin consistent with the high degree of selectivity, enabling Phase 1 clinical trials using a crystalline formulation of PLX4032 (ref. 5). In a subset of melanoma patients, pathway inhibition was monitored in paired biopsy specimens collected before treatment initiation and following two weeks of treatment. This analysis revealed substantial inhibition of ERK phosphorylation, yet clinical evaluation did not show tumour regressions. At higher drug exposures afforded by a new amorphous drug formulation, greater than 80% inhibition of ERK phosphorylation in the tumours of patients correlated with clinical response. Indeed, the Phase 1 clinical data revealed a remarkably high 81% response rate in metastatic melanoma patients treated at an oral dose of 960 mg twice daily. These data demonstrate that BRAF-mutant melanomas are highly dependent on B-RAF kinase activity.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2948082/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2948082/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bollag, Gideon -- Hirth, Peter -- Tsai, James -- Zhang, Jiazhong -- Ibrahim, Prabha N -- Cho, Hanna -- Spevak, Wayne -- Zhang, Chao -- Zhang, Ying -- Habets, Gaston -- Burton, Elizabeth A -- Wong, Bernice -- Tsang, Garson -- West, Brian L -- Powell, Ben -- Shellooe, Rafe -- Marimuthu, Adhirai -- Nguyen, Hoa -- Zhang, Kam Y J -- Artis, Dean R -- Schlessinger, Joseph -- Su, Fei -- Higgins, Brian -- Iyer, Raman -- D'Andrea, Kurt -- Koehler, Astrid -- Stumm, Michael -- Lin, Paul S -- Lee, Richard J -- Grippo, Joseph -- Puzanov, Igor -- Kim, Kevin B -- Ribas, Antoni -- McArthur, Grant A -- Sosman, Jeffrey A -- Chapman, Paul B -- Flaherty, Keith T -- Xu, Xiaowei -- Nathanson, Katherine L -- Nolop, Keith -- K24 CA097588/CA/NCI NIH HHS/ -- P50 CA093372/CA/NCI NIH HHS/ -- P50 CA093372-01/CA/NCI NIH HHS/ -- R01 CA118871/CA/NCI NIH HHS/ -- R01 CA118871-01A1/CA/NCI NIH HHS/ -- England -- Nature. 2010 Sep 30;467(7315):596-9. doi: 10.1038/nature09454.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Plexxikon Inc., 91 Bolivar Drive, Berkeley, California 94710, USA. gbollag@plexxikon.com〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20823850" target="_blank"〉PubMed〈/a〉
    Keywords: Alleles ; Animals ; Dogs ; Extracellular Signal-Regulated MAP Kinases/antagonists & inhibitors/metabolism ; Humans ; Indoles/administration & dosage/adverse effects/chemistry/*therapeutic use ; MAP Kinase Signaling System/drug effects ; Macaca fascicularis ; Melanoma/*drug therapy/*enzymology/genetics/pathology ; Models, Molecular ; Mutant Proteins/antagonists & inhibitors/chemistry/genetics/metabolism ; Mutation/*genetics ; Neoplasm Metastasis ; Phosphorylation/drug effects ; Positron-Emission Tomography ; Proto-Oncogene Proteins B-raf/*antagonists & ; inhibitors/chemistry/genetics/metabolism ; Rats ; Substrate Specificity ; Sulfonamides/administration & dosage/adverse effects/chemistry/*therapeutic use ; Xenograft Model Antitumor Assays
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2011-11-25
    Description: Activated RAS promotes dimerization of members of the RAF kinase family. ATP-competitive RAF inhibitors activate ERK signalling by transactivating RAF dimers. In melanomas with mutant BRAF(V600E), levels of RAS activation are low and these drugs bind to BRAF(V600E) monomers and inhibit their activity. This tumour-specific inhibition of ERK signalling results in a broad therapeutic index and RAF inhibitors have remarkable clinical activity in patients with melanomas that harbour mutant BRAF(V600E). However, resistance invariably develops. Here, we identify a new resistance mechanism. We find that a subset of cells resistant to vemurafenib (PLX4032, RG7204) express a 61-kDa variant form of BRAF(V600E), p61BRAF(V600E), which lacks exons 4-8, a region that encompasses the RAS-binding domain. p61BRAF(V600E) shows enhanced dimerization in cells with low levels of RAS activation, as compared to full-length BRAF(V600E). In cells in which p61BRAF(V600E) is expressed endogenously or ectopically, ERK signalling is resistant to the RAF inhibitor. Moreover, a mutation that abolishes the dimerization of p61BRAF(V600E) restores its sensitivity to vemurafenib. Finally, we identified BRAF(V600E) splicing variants lacking the RAS-binding domain in the tumours of six of nineteen patients with acquired resistance to vemurafenib. These data support the model that inhibition of ERK signalling by RAF inhibitors is dependent on levels of RAS-GTP too low to support RAF dimerization and identify a novel mechanism of acquired resistance in patients: expression of splicing isoforms of BRAF(V600E) that dimerize in a RAS-independent manner.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3266695/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3266695/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Poulikakos, Poulikos I -- Persaud, Yogindra -- Janakiraman, Manickam -- Kong, Xiangju -- Ng, Charles -- Moriceau, Gatien -- Shi, Hubing -- Atefi, Mohammad -- Titz, Bjoern -- Gabay, May Tal -- Salton, Maayan -- Dahlman, Kimberly B -- Tadi, Madhavi -- Wargo, Jennifer A -- Flaherty, Keith T -- Kelley, Mark C -- Misteli, Tom -- Chapman, Paul B -- Sosman, Jeffrey A -- Graeber, Thomas G -- Ribas, Antoni -- Lo, Roger S -- Rosen, Neal -- Solit, David B -- K22 CA151638/CA/NCI NIH HHS/ -- P30 CA008748/CA/NCI NIH HHS/ -- R01 CA127240/CA/NCI NIH HHS/ -- R01 CA127240-01A1/CA/NCI NIH HHS/ -- T32 CACA062948-15/PHS HHS/ -- Intramural NIH HHS/ -- England -- Nature. 2011 Nov 23;480(7377):387-90. doi: 10.1038/nature10662.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Pharmacology and Chemistry, Memorial Sloan-Kettering Cancer Center, New York, New York 10065, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22113612" target="_blank"〉PubMed〈/a〉
    Keywords: Alternative Splicing/*genetics ; Animals ; Cell Line, Tumor ; Drug Resistance, Neoplasm/drug effects/*genetics ; Exons/genetics ; Extracellular Signal-Regulated MAP Kinases/metabolism ; Humans ; Indoles/pharmacology ; MAP Kinase Signaling System/drug effects ; Melanoma/enzymology/metabolism/pathology ; Mice ; Mutant Proteins/chemistry/genetics/metabolism ; Protein Isoforms/chemistry/genetics/metabolism ; Protein Kinase Inhibitors/pharmacology ; Protein Multimerization/drug effects/*genetics ; Proto-Oncogene Proteins B-raf/antagonists & ; inhibitors/chemistry/*genetics/*metabolism ; Sulfonamides/pharmacology
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2014-11-28
    Description: The development of human cancer is a multistep process characterized by the accumulation of genetic and epigenetic alterations that drive or reflect tumour progression. These changes distinguish cancer cells from their normal counterparts, allowing tumours to be recognized as foreign by the immune system. However, tumours are rarely rejected spontaneously, reflecting their ability to maintain an immunosuppressive microenvironment. Programmed death-ligand 1 (PD-L1; also called B7-H1 or CD274), which is expressed on many cancer and immune cells, plays an important part in blocking the 'cancer immunity cycle' by binding programmed death-1 (PD-1) and B7.1 (CD80), both of which are negative regulators of T-lymphocyte activation. Binding of PD-L1 to its receptors suppresses T-cell migration, proliferation and secretion of cytotoxic mediators, and restricts tumour cell killing. The PD-L1-PD-1 axis protects the host from overactive T-effector cells not only in cancer but also during microbial infections. Blocking PD-L1 should therefore enhance anticancer immunity, but little is known about predictive factors of efficacy. This study was designed to evaluate the safety, activity and biomarkers of PD-L1 inhibition using the engineered humanized antibody MPDL3280A. Here we show that across multiple cancer types, responses (as evaluated by Response Evaluation Criteria in Solid Tumours, version 1.1) were observed in patients with tumours expressing high levels of PD-L1, especially when PD-L1 was expressed by tumour-infiltrating immune cells. Furthermore, responses were associated with T-helper type 1 (TH1) gene expression, CTLA4 expression and the absence of fractalkine (CX3CL1) in baseline tumour specimens. Together, these data suggest that MPDL3280A is most effective in patients in which pre-existing immunity is suppressed by PD-L1, and is re-invigorated on antibody treatment.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Herbst, Roy S -- Soria, Jean-Charles -- Kowanetz, Marcin -- Fine, Gregg D -- Hamid, Omid -- Gordon, Michael S -- Sosman, Jeffery A -- McDermott, David F -- Powderly, John D -- Gettinger, Scott N -- Kohrt, Holbrook E K -- Horn, Leora -- Lawrence, Donald P -- Rost, Sandra -- Leabman, Maya -- Xiao, Yuanyuan -- Mokatrin, Ahmad -- Koeppen, Hartmut -- Hegde, Priti S -- Mellman, Ira -- Chen, Daniel S -- Hodi, F Stephen -- 1R01CA155196/CA/NCI NIH HHS/ -- P30 CA 016359/CA/NCI NIH HHS/ -- P30 CA016359/CA/NCI NIH HHS/ -- R01 CA155196/CA/NCI NIH HHS/ -- England -- Nature. 2014 Nov 27;515(7528):563-7. doi: 10.1038/nature14011.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Yale Comprehensive Cancer Center, Yale School of Medicine, 333 Cedar Street, WWW221, New Haven, Connecticut 06520, USA. ; Gustave Roussy South-Paris University, 114 Rue Edouard Vaillant, 94805 Villefuij, Cedex, France. ; Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, USA. ; The Angeles Clinic and Research Institute, 11818 Wilshire Blvd, Los Angeles, California 90025, USA. ; Pinnacle Oncology Hematology, 9055 E Del Camino Dr 100, Scottsdale, Arizona 85258, USA. ; Vanderbilt-Ingram Cancer Center, 2220 Pierce Avenue, Nashville, Tennessee 37212, USA. ; Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Shapiro 9, Boston, Massachusetts 02215, USA. ; Carolina BioOncology Institute, 9801 W. Kincey Ave, Suite 145, Huntersville, North Carolina 28078, USA. ; Stanford University, CCSR Bldg Room 1110, Stanford, California 94305, USA. ; Vanderbilt-Ingram Cancer Center, 1301 Medical Center Dr, Suite 1710, Nashville, Tennessee 37212, USA. ; Massachusetts General Hospital, 55 Fruit Street, YAW 9E, Boston, Massachusetts 02114, USA. ; Dana-Farber/Brigham and Women's Cancer Center, 450 Brookline Avenue, Boston, Massachusetts 02215, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25428504" target="_blank"〉PubMed〈/a〉
    Keywords: Adult ; Aged ; Aged, 80 and over ; Antibodies, Monoclonal/adverse effects/*therapeutic use ; Antigens, CD274/*antagonists & inhibitors/metabolism ; Biomarkers/blood ; CTLA-4 Antigen/metabolism ; Chemokine CX3CL1/metabolism ; Clinical Protocols ; Disease-Free Survival ; Female ; *Gene Expression Regulation, Neoplastic ; Humans ; *Immunotherapy/adverse effects ; Lymphocytes, Tumor-Infiltrating/immunology ; Male ; Middle Aged ; Neoplasms/diagnosis/*therapy ; Treatment Outcome ; Young Adult
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 1995-03-01
    Print ISSN: 0167-6997
    Electronic ISSN: 1573-0646
    Topics: Chemistry and Pharmacology , Medicine
    Published by Springer
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