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

Cell Rep. 2016 Jun 28;16(1):263-277. doi: 10.1016/j.celrep.2016.05.064. Epub 2016 Jun 16.


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.

MeSH terms

  • Animals
  • Biomarkers, Tumor / metabolism
  • Cell Line, Tumor
  • Chromosome Aberrations
  • Drug Resistance, Neoplasm / drug effects
  • Gene Duplication*
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Indoles / pharmacology
  • Indoles / therapeutic use
  • MAP Kinase Signaling System / drug effects
  • Melanoma / drug therapy*
  • Melanoma / genetics*
  • Melanoma / pathology
  • Mice
  • Mutation / genetics
  • Neoplasm Metastasis
  • Protein Domains
  • Protein Multimerization
  • Proto-Oncogene Proteins B-raf / chemistry*
  • Proto-Oncogene Proteins B-raf / genetics*
  • Reproducibility of Results
  • Sulfonamides / pharmacology
  • Sulfonamides / therapeutic use
  • Vemurafenib
  • Xenograft Model Antitumor Assays*


  • Biomarkers, Tumor
  • Indoles
  • Sulfonamides
  • Vemurafenib
  • Proto-Oncogene Proteins B-raf