Synthesis of a 11C-Isotopologue of the B-Raf-Selective Inhibitor Encorafenib Using In-Loop [11C]CO2 Fixation.

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Abstract

The serine/threonine kinase B-Raf is an essential regulator of cellular growth, differentiation, and survival. B-Raf protein expression is elevated throughout melanoma progression, making it an attractive target for noninvasive imaging using positron-emission tomography. Encorafenib is a potent and highly selective inhibitor of B-Raf used in the clinical management of melanoma. In this study, the radiosynthesis of a 11C-isotopologue of encorafenib was developed using an in-loop [11C]CO2 fixation reaction. Optimization of reaction conditions reduced the formation of a radiolabeled side product and improved the isolated yields of [11C]encorafenib (14.5 ± 2.4% radiochemical yield). The process was fully automated using a commercial radiosynthesizer for the production of 6845 ± 888 MBq of [11C]encorafenib in high molar activity (177 ± 5 GBq μmol-1), in high radiochemical purity (99%), and in a formulation suitable for animal injection. An in vitro cellular binding experiment demonstrated saturable binding of the radiotracer to A375 melanoma cells.

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The global burden of melanoma: results from the Global Burden of Disease Study 2015

C Karimkhani, A.C. Green, T. Nijsten … (2017)

Summary Background Despite recent improvements in prevention, diagnosis and treatment, vast differences in melanoma burden still exist between populations. Comparative data can highlight these differences and lead to focused efforts to reduce the burden of melanoma. Objectives To assess global, regional and national melanoma incidence, mortality and disability‐adjusted life year (DALY) estimates from the Global Burden of Disease Study 2015. Methods Vital registration system and cancer registry data were used for melanoma mortality modelling. Incidence and prevalence were estimated using separately modelled mortality‐to‐incidence ratios. Total prevalence was divided into four disease phases and multiplied by disability weights to generate years lived with disability (YLDs). Deaths in each age group were multiplied by the reference life expectancy to generate years of life lost (YLLs). YLDs and YLLs were added to estimate DALYs. Results The five world regions with the greatest melanoma incidence, DALY and mortality rates were Australasia, North America, Eastern Europe, Western Europe and Central Europe. With the exception of regions in sub‐Saharan Africa, DALY and mortality rates were greater in men than in women. DALY rate by age was highest in those aged 75–79 years, 70–74 years and ≥ 80 years. Conclusions The greatest burden from melanoma falls on Australasian, North American, European, elderly and male populations, which is consistent with previous investigations. These substantial disparities in melanoma burden worldwide highlight the need for aggressive prevention efforts. The Global Burden of Disease Study results can help shape melanoma research and public policy.

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Assessment of BRAF V600E mutation status by immunohistochemistry with a mutation-specific monoclonal antibody.

David Capper, Matthias Preusser, Antje Habel … (2011)

Activating mutations of the serine threonine kinase v-RAF murine sarcoma viral oncogene homolog B1 (BRAF) are frequent in benign and malignant human tumors and are emerging as an important biomarker. Over 95% of BRAF mutations are of the V600E type and specific small molecular inhibitors are currently under pre-clinical or clinical investigation. BRAF mutation status is determined by DNA-based methods, most commonly by sequencing. Here we describe the development of a monoclonal BRAF V600E mutation-specific antibody that can differentiate BRAF V600E and wild type protein in routinely processed formalin-fixed and paraffin-embedded tissue. A total of 47 intracerebral melanoma metastases and 21 primary papillary thyroid carcinomas were evaluated by direct sequencing of BRAF and by immunohistochemistry using the BRAF V600E mutation-specific antibody clone VE1. Correlation of VE1 immunohistochemistry and BRAF sequencing revealed a perfect match for both papillary thyroid carcinomas and melanoma metastases. The staining intensity in BRAF V600E mutated tumor samples ranged from weak to strong. The generally homogenous VE1 staining patterns argue against a clonal heterogeneity of the tumors investigated. Caution is essential when only poorly preserved tissue is available for VE1 immunohistochemical analysis or when tissues with only little total BRAF protein are analyzed. Immunohistochemistry using antibody VE1 may substantially facilitate molecular analysis of BRAF V600E status for diagnostic, prognostic, and predictive purposes.

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Frequency and spectrum of BRAF mutations in a retrospective, single-institution study of 1112 cases of melanoma.

Wesley O Greaves, Shalini Verma, Keyur Patel … (2013)

The US Food and Drug Administration (FDA) approved vemurafenib to treat patients with metastatic melanoma harboring the BRAF c.1799T>A (p.V600E) mutation. However, a subset of melanomas harbor non-p.V600E BRAF mutations, and these data are of potential importance regarding the efficacy of current targeted therapies. To better understand the BRAF mutation profile in melanomas, we retrospectively analyzed data from 1112 primary and metastatic melanomas at our institution. The cohort included nonacral cutaneous (n = 774), acral (n = 111), mucosal (n = 26), uveal (n = 23), leptomeningeal (n = 1), and metastatic melanomas of unknown primary site (n = 177). BRAF mutation hotspot regions in exons 11 and 15 were analyzed by pyrosequencing or with the primer extension MassARRAY system. A total of 499 (44.9%) specimens exhibited BRAF mutations, involving exon 15 [497 (99.6%)] or exon 11 [2 (0.4%)]. p.V600E was detected in 376 (75.4%) cases; the remaining 123 (24.6%) cases exhibited non-p.V600E mutations, of which p.V600K was most frequent [86 (17.2%)]. BRAF mutations were more frequent in nonacral cutaneous (51.4%) than acral melanomas [18 (16.2%)] (P < 0.001); however, there was no significant difference among cutaneous histological subtypes. All mucosal, uveal, and leptomeningeal melanomas were BRAF wild type (WT). The high frequency of non-p.V600E BRAF mutations in melanoma has important implications because the FDA-approved companion diagnostic test for p.V600E detects some but not all non-p.V600E mutations. However, the therapeutic efficacy of vemurafenib is not well established in these lesions. Copyright © 2013 American Society for Investigative Pathology and the Association for Molecular Pathology. Published by Elsevier Inc. All rights reserved.