Low BRAF and NRAS expression levels are associated with clinical benefit from DTIC therapy and prognosis in metastatic melanoma

Clin Exp Metastasis. 2013 Oct;30(7):867-76. doi: 10.1007/s10585-013-9587-4. Epub 2013 May 15.

Abstract

Metastatic melanoma is characterized by a poor response to chemotherapy. Furthermore, there is a lack of established predictive and prognostic markers. In this single institution study, we correlated mutation status and expression levels of BRAF and NRAS to dacarbazine (DTIC) treatment response as well as progression-free and overall survival in a cohort of 85 patients diagnosed with advanced melanoma. Neither BRAF nor NRAS mutation status correlated to treatment response. However, patients with tumors harboring NRAS mutations had a shorter overall survival (p < 0.001) compared to patients with tumors wild-type for NRAS. Patients having a clinical benefit (objective response or stable disease at 3 months) on DTIC therapy had lower BRAF and NRAS expression levels compared to patients progressing on therapy (p = 0.037 and 0.003, respectively). For BRAF expression, this association was stronger among patients with tumors wild-type for BRAF (p = 0.005). Further, low BRAF as well as NRAS expression levels were associated with a longer progression-free survival in the total population (p = 0.004 and <0.001, respectively). Contrasting low NRAS expression levels, which were associated with improved overall survival in the total population (p = 0.01), low BRAF levels were associated with improved overall survival only among patients with tumors wild-type for BRAF (p = 0.013). These findings indicate that BRAF and NRAS expression levels may influence responses to DTIC as well as prognosis in patients with advanced melanoma.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Antineoplastic Agents, Alkylating / therapeutic use*
  • Dacarbazine / therapeutic use*
  • Disease-Free Survival
  • Female
  • GTP Phosphohydrolases / genetics*
  • Humans
  • Male
  • Melanoma / drug therapy*
  • Melanoma / genetics
  • Melanoma / pathology
  • Membrane Proteins / genetics*
  • Middle Aged
  • Neoplasm Metastasis*
  • Prognosis
  • Proto-Oncogene Proteins B-raf / genetics*
  • RNA, Messenger / genetics

Substances

  • Antineoplastic Agents, Alkylating
  • Membrane Proteins
  • RNA, Messenger
  • Dacarbazine
  • BRAF protein, human
  • Proto-Oncogene Proteins B-raf
  • GTP Phosphohydrolases
  • NRAS protein, human