Molecular testing in malignant melanoma

Abstract

Molecular testing of cancers to determine therapeutic eligibility is now standard of care and has changed the practice of pathology. Recent advances in the treatment of metastatic melanoma with BRAF and KIT inhibitors have increased the demand for molecular testing in melanoma. Furthermore, rapid progress is being made in determining potential new targets, mechanisms of resistance, and developing additional rationally designed therapies. The likely consequence will be a significant expansion of molecular testing for melanoma to include an array of multiple signaling intermediates. Currently, routine testing is mostly limited to BRAF and KIT. Mutations in these genes generally occur in a distinct group of melanoma subsets though, and with the numerous techniques available for mutation analysis, decisions about testing can be complex. The purpose of this review is to provide an overview of clinically relevant mutations which currently guide systemic therapy in Stage IV melanoma, how these molecular events vary with melanoma subtype and primary site of origin, and practical recommendations for testing.

Euphorbia fischeriana Steud inhibits malignant melanoma via modulation of the phosphoinositide-3-kinase/Akt signaling pathway

“…The majority (~90%) of patients with early detected melanoma are curable; however, the efficiency of clinical drugs in the treatment of patients with advanced metastatic melanoma is <20% (2), and the 5-year survival rate is <5%, with a median survival time of only 2-8 months (3,4). Numerous studies have confirmed that the poor prognosis of malignant melanoma is primarily attributable to the high incidence of distant metastasis and a strong capacity for invasion (5)(6)(7). Therefore, the development of more effective therapies for the inhibition of metastasis presents a challenge for the treatment of malignant melanoma.…”

Mitogen-Activated Protein Kinase Signaling Pathway in Cutaneous Melanoma: An Updated Review

“…17 The histologic subtype that more often shows BRAF mutations is superficial spreading melanoma; the acral, mucosal, uveal, and lentigo maligna variants usually have a wild-type BRAF. 17 Of the 3 RAF genes that participate in the ERK1/2 signal transduction cascade (ie, ARAF, BRAF, and CRAF), BRAF is the one that is most frequently affected in cutaneous melanoma. This is probably because, unlike ARAF and CRAF, BRAF requires the phosphorylation of only a single amino acid within the activation loop to become active.…”

“…17 Also, Sanger sequencing still seems to have some advantages over mutation-specific assays. Although the sensitivity of the cobas 4800 test for the detection of the BRAF V600E has been shown to be comparable with, or even better than, that of Sanger sequencing, the latter also allows for the detection of BRAF mutations other than V600E.…”

“…17 A practically useful approach is to perform an initial screening for BRAF or c-KIT mutations with high-resolution melting-curve analysis, followed by sequencing confirmation, usually with pyrosequencing. 17,27 Other, less frequently used techniques for detecting BRAF and c-KIT mutations are single-nucleotide primer extension, mutation-specific polymerase chain reaction (amplification refractory mutation system), and deep sequencing. 17 Because targeted therapeutic agents are not used in lowstage localized disease, often the only specimen available for testing is a cytologic sample obtained by fine-needle aspiration.…”

“…17,27 Other, less frequently used techniques for detecting BRAF and c-KIT mutations are single-nucleotide primer extension, mutation-specific polymerase chain reaction (amplification refractory mutation system), and deep sequencing. 17 Because targeted therapeutic agents are not used in lowstage localized disease, often the only specimen available for testing is a cytologic sample obtained by fine-needle aspiration. Molecular analysis can be performed on either a smear or a cell block, ideally with tumor cell enrichment by microdissection.…”