Article

Targeting BRAF in Advanced Melanoma: A First Step toward Manageable Disease

Program of Molecular and Cellular Oncogenesis, The Wistar Institute, Philadelphia, Pennsylvania 19104, USA.
Clinical Cancer Research (Impact Factor: 8.19). 03/2011; 17(7):1658-63. DOI: 10.1158/1078-0432.CCR-10-0174
Source: PubMed

ABSTRACT Melanoma is the deadliest form of skin cancer and its incidence has been increasing worldwide. The disease manifests itself as clinically and genetically distinct subgroups, indicating the need for patient-specific diagnostic and treatment tools. The discovery of activating mutations (V600E) in the BRAF kinase in approximately 50% of patients spurred the development of compounds to inhibit aberrant BRAF activity, and the first drug candidate to show promising clinical activity is PLX4032 (also known as RG7204). Most recent clinical data from a phase II trial indicate that PLX4032 causes tumor regression and stabilized disease in >50% of advanced melanoma patients harboring BRAF V600E tumors. These data validate the effectiveness of oncogene-targeted therapy against advanced melanoma and offer hope that the disease can be overcome. However, as melanoma is dynamic and heterogeneous, careful treatment strategies and combination therapies are warranted to obtain long-term clinical effects.

Full-text

Available from: Adina Vultur, Jun 08, 2015
0 Followers
 · 
125 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Vertical growth phase (VGP) melanoma is frequently metastatic, a process mediated by changes in gene expression, which are directed by signal transduction pathways in the tumor cells. A prominent signaling pathway is the Ras-Raf-Mek-Erk MAPK pathway, which increases expression of genes that promote melanoma progression. Many melanomas harbor a mutation in this pathway, BRAF(V600E), which constitutively activates MAPK signaling and expression of downstream target genes that facilitate tumor progression. In BRAF(V600E) melanoma, the small molecule inhibitor, vemurafenib (PLX4032), has revolutionized therapy for melanoma by inducing rapid tumor regression. This compound down-regulates the expression of many genes. However, in this study, we document that blocking the Ras-Raf-Mek-Erk MAPK pathway, either with an ERK (PLX4032) or a MEK (U1026) signaling inhibitor, in BRAF(V600E) human and murine melanoma cell lines increases collagen synthesis in vitro and collagen deposition in vivo. Since TGFß signaling is a major mediator of collagen synthesis, we examined whether blocking TGFß signaling with a small molecule inhibitor would block this increase in collagen. However, there was minimal reduction in collagen synthesis in response to blocking TGFß signaling, suggesting additional mechanism(s), which may include activation of the p38 MAPK pathway. Presently, it is unclear whether this increased collagen synthesis and deposition in melanomas represents a therapeutic benefit or an unwanted "off target" effect of inhibiting the Ras-Raf-Erk-Mek pathway. Copyright © 2015. Published by Elsevier B.V.
    Matrix biology: journal of the International Society for Matrix Biology 05/2015; 5. DOI:10.1016/j.matbio.2015.05.007 · 3.65 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: As the increased knowledge of tumour heterogeneity and genetic alterations progresses, it exemplifies the need for further personalized medicine in modern cancer management. Here, the similarities but also the differential effects of RAS and BRAF oncogenic signalling are examined and further implications in personalized cancer diagnosis and therapy are discussed. Redundant mechanisms mediated by the two oncogenes as well as differential regulation of signalling pathways and gene expression by RAS as compared to BRAF are addressed. The implications of RAS vs BRAF differential functions, in relevant tumour types including colorectal cancer, melanoma, lung cancer are discussed. Current therapeutic findings and future viewpoints concerning the exploitation of RAS-BRAF-pathway alterations for the development of novel therapeutics and efficient rational combinations, as well as companion tests for relevant markers of response will be evaluated. The concept that drug-resistant cells may also display drug dependency, such that altered dosing may prevent the emergence of lethal drug resistance posed a major therapy hindrance.
    Oncotarget 10/2014; · 6.63 Impact Factor
  • Source