About these slides SPEC – Short Presentation in Emerging Concepts Provided by the CAP as an aid to pathologists to facilitate discussion on the topic. Content has been reviewed by experts at the CAP, but does not necessarily reflect the official opinion of the College of American Pathologists. Non-CAP material with identified copyright source may only be copied or distributed under a license (permission) from the copyright holder, or under the doctrine of fair use. Version 1.2, rev. 7/15/2014

Emerging Concepts in Therapeutic Guidance for Metastatic Melanoma Short Presentations in Emerging Concepts (SPEC)

Melanoma Leading cause of death from skin disease Discovery of genes that play a key role in oncogenesis –e.g. BRAF, NRAS, MEK, c-KIT Emerging therapies focus on targeting the activated pathways in melanoma

Molecular Subtypes of Melanoma?

BRAF About 50% of nodular melanomas –Acquired mutation –RAS/RAF/MEK pathway is constitutively activated driving proliferation Most common mutation: V600E –Mutation in DNA causes change in protein amino acid sequence: Valine at amino acid 600 to GlutaminE Second common mutation: V600K –Same amino acid – Valine to Lysine

BRAF Inhibitors Vemurafenib (Aug 2011) Dabrafenib (May 2013) Oral inhibitors of BRAF tyrosine kinase Can have dramatic tumor regression –Subject of 3 part series in New York Times, Feb 2010

Phase 3 Trial Results Improved survival with vemurafenib in melanoma with BRAF V600E mutation RESULTS: At 6 months, overall survival was 84% (95% confidence interval [CI], 78 to 89) in the vemurafenib group and 64% (95% CI, 56 to 73) in the dacarbazine group. In the interim analysis for overall survival and final analysis for progression-free survival, vemurafenib was associated with a relative reduction of 63% in the risk of death and of 74% in the risk of either death or disease progression, as compared with dacarbazine (P<0.001 for both comparisons). After review of the interim analysis by an independent data and safety monitoring board, crossover from dacarbazine to vemurafenib was recommended. Response rates were 48% for vemurafenib and 5% for dacarbazine. Common adverse events associated with vemurafenib were arthralgia, rash, fatigue, alopecia, keratoacanthoma or squamous- cell carcinoma, photosensitivity, nausea, and diarrhea; 38% of patients required dose modification because of toxic effects.

J Clin Oncol Apr 1;29(10):

BRAF Mutation Analysis Either primary or metastatic tissue –Formalin-fixed paraffin-embedded (FFPE) Performed using PCR –Very good analytic sensitivity - about 1% –Detects the BRAF mutation with less than 5% tumor cells in the tissue. –More sensitive than sequencing Can be significant in samples with low amount of tumor

Resistance to BRAF Inhibitors Resistance develops through alternate pathway activation of NRAS/MEK Therapeutic option for MEK inhibition using trametinib –FDA approval for monotherapy in BRAF mutated tumors –Not approved as a combination treatment. Preliminary results from a clinical trial suggest that use in combination with dabrafenib significantly improved progression-free survival, although the incidence of pyrexia was increased

c-KIT and Melanoma Mucosal or acral melanomas with activating mutations or amplifications in c- KIT may be sensitive to a variety of c-KIT inhibitors Phase II and phase III trials are available for patients with unresectable stage III or stage IV melanoma harboring the c-KIT mutation

c-KIT testing Response to inhibitors is limited to mutations in certain exons –Amplification not associated with response Image from: Lyle M, Long GV. Diagnosis and Treatment of KIT-Mutant Metastatic Melanoma. J Clin Oncol Sep 10;31(26):

Selected Resources Improved survival with vemurafenib in melanoma with BRAF V600E mutation Chapman PB et al, Improved survival with vemurafenib in melanoma with BRAF V600E mutation. N Engl J Med. 2011; 364: June 30, Vemurafenib (Zelboraf ® ) package insert

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