Dataset Information

BRAF(V600E) Kinase Domain Duplication Identified in Therapy-Refractory Melanoma Patient-Derived Xenografts.

ABSTRACT: The therapeutic landscape of melanoma is improving rapidly. Targeted inhibitors show promising results, but drug resistance often limits durable clinical responses. There is a need for in vivo systems that allow for mechanistic drug resistance studies and (combinatorial) treatment optimization. Therefore, we established a large collection of patient-derived xenografts (PDXs), derived from BRAF(V600E), NRAS(Q61), or BRAF(WT)/NRAS(WT) melanoma metastases prior to treatment with BRAF inhibitor and after resistance had occurred. Taking advantage of PDXs as a limitless source, we screened tumor lysates for resistance mechanisms. We identified a BRAF(V600E) protein harboring a kinase domain duplication (BRAF(V600E/DK)) in ?10% of the cases, both in PDXs and in an independent patient cohort. While BRAF(V600E/DK) depletion restored sensitivity to BRAF inhibition, a pan-RAF dimerization inhibitor effectively eliminated BRAF(V600E/DK)-expressing cells. These results illustrate the utility of this PDX platform and warrant clinical validation of BRAF dimerization inhibitors for this group of melanoma patients.

SUBMITTER: Kemper K

PROVIDER: S-EPMC4929150 | biostudies-literature | 2016 Jun

REPOSITORIES: biostudies-literature

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BRAF(V600E) Kinase Domain Duplication Identified in Therapy-Refractory Melanoma Patient-Derived Xenografts.

Kemper Kristel K Krijgsman Oscar O Kong Xiangjun X Cornelissen-Steijger Paulien P Shahrabi Aida A Weeber Fleur F van der Velden Daphne L DL Bleijerveld Onno B OB Kuilman Thomas T Kluin Roel J C RJC Sun Chong C Voest Emile E EE Ju Young Seok YS Schumacher Ton N M TNM Altelaar A F Maarten AFM McDermott Ultan U Adams David J DJ Blank Christian U CU Haanen John B JB Peeper Daniel S DS

Cell reports 20160616 1

The therapeutic landscape of melanoma is improving rapidly. Targeted inhibitors show promising results, but drug resistance often limits durable clinical responses. There is a need for in vivo systems that allow for mechanistic drug resistance studies and (combinatorial) treatment optimization. Therefore, we established a large collection of patient-derived xenografts (PDXs), derived from BRAF(V600E), NRAS(Q61), or BRAF(WT)/NRAS(WT) melanoma metastases prior to treatment with BRAF inhibitor and ...[more]

PMID: 27320919

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Project description:BackgroundMost mutations in melanoma affect one critical amino acid on BRAF gene, resulting in the V600E substitution. Patient management is often based on the use of specific inhibitors targeting this mutation.MethodsDNA and RNA mutation status was assessed in 15 melanoma cell lines by Sanger sequencing and RNA-seq. We tested the cell lines responsiveness to BRAF inhibitors (vemurafenib and PLX4720, BRAF-specific and sorafenib, BRAF non-specific). Cell proliferation was assessed by MTT colorimetric assay. BRAF V600E RNA expression was assessed by qPCR. Expression level of phosphorylated-ERK protein was assessed by Western Blotting as marker of BRAF activation.ResultsThree cell lines were discordant in the mutation detection (BRAF V600E at DNA level/Sanger sequencing and BRAF WT on RNA-seq). We initially postulated that those cell lines may express only the WT allele at the RNA level although mutated at the DNA level. A more careful analysis showed that they express low level of BRAF RNA and the expression may be in favor of the WT allele. We tested whether the discordant cell lines responded differently to BRAF-specific inhibitors. Their proliferation rate decreased after treatment with vemurafenib and PLX4720 but was not affected by sorafenib, suggesting a BRAF V600E biological behavior. Yet, responsiveness to the BRAF specific inhibitors was lower as compared to the control. Western Blot analysis revealed a decreased expression of p-ERK protein in the BRAF V600E control cell line and in the discordant cell lines upon treatment with BRAF-specific inhibitors. The discordant cell lines showed a lower responsiveness to BRAF inhibitors when compared to the BRAF V600E control cell line. The results obtained from the inhibition experiment and molecular analyses were also confirmed in three additional cell lines.ConclusionCell lines carrying V600E mutation at the DNA level may respond differently to BRAF targeted treatment potentially due to a lower V600E RNA expression.

Project description:BACKGROUND:Approximately one third of women who develop melanoma at childbearing age are diagnosed during gestation or the postpartum period, facing pregnancy-associated melanoma (PAM). However, only some retrospective studies with heterogeneous data have analyzed the impact of pregnancy on melanoma development, and no evidence exists about the behavior and the management of BRAF-mutated disease. SUBJECTS, MATERIALS, AND METHODS:In order to better describe the evolution of BRAF V600E-mutated PAM, we present here all consecutive cases diagnosed in our site during the last 7?years, recording oncological, obstetrical, and perinatal parameters, as well as the therapeutic decisions for both melanoma and gestation. Based on our institutional experience, we weigh the current published evidence and discuss upcoming clinical considerations about the prognosis of PAM, the role of BRAF status, and the possible treatment options during pregnancy in localized or advanced/metastatic disease. Five women were diagnosed with newly metastatic or relapsed BRAF V600E-mutated PAM (four during gestation and one in the 1st year postpartum) between 2012 and 2019. All of them developed extensive metastatic disease with multiple organ involvement, and four developed brain metastases. All cases experienced melanoma progression in less than 6 months under targeted therapy and died soon independently of the followed sequence of treatments. All the neonates were delivered alive and healthy, but one developed melanoma earlier than the second year of life. RESULTS:Reviewing the literature to confirm our unfavorable outcomes, no specific data on BRAF-mutated PAM were retrieved and current evidence still supports that the prognosis of PAM should be guided by the established risk factors, whereas the management of advanced/metastatic PAM should be evaluated on a case-by-case basis. CONCLUSION:More data are required to ascertain whether BRAF-mutated profile adversely affects PAM outcome, although the clinicians should be aware to detect any potential melanoma lesion during pregnancy as soon as possible, treating it locally, regardless of its BRAF status. IMPLICATIONS FOR PRACTICE:The prognosis and management of pregnancy-associated melanoma whether BRAF-mutated or wild type, is currently guided by the same parameters as in the nonpregnant condition. In this special nontrial subpopulation, BRAF-mutated status seems to have a detrimental effect on disease outcome, independently of the following treatments. In early stage melanoma, wide local excision with or without sentinel lymph node dissection may be curative at any trimester of gestation, while in advanced/metastatic setting, therapeutic strategy including immune-checkpoint or BRAF/MEK inhibitors, is more challenging, regardless of BRAF status, and should be based on an individualized decision in each case at a multidisciplinary level.

Dataset Information

BRAF(V600E) Kinase Domain Duplication Identified in Therapy-Refractory Melanoma Patient-Derived Xenografts.

Publications

BRAF(V600E) Kinase Domain Duplication Identified in Therapy-Refractory Melanoma Patient-Derived Xenografts.

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