In:
Journal of Clinical Oncology, American Society of Clinical Oncology (ASCO), Vol. 31, No. 15_suppl ( 2013-05-20), p. 9092-9092
Abstract:
9092 Background: To select melanoma patients for treatment with BRAF inhibitors, the BRAF mutational status is determined in the most recent tumor biopsy. However, tumor specimens are not always available for the analysis, and relying on a single biopsy specimen can potentially exclude from treatment patients with heterogeneity among metastatic tumors due to polyclonality of BRAF mutation, which appears as a rather common condition. As an alternative approach we explored a blood-based mutation detection assay. Methods: We developed a method including enrichment for the BRAV600E variant by selective elimination of the wild type allele by TspRI digestion and BRAFV600E detection by TaqMan Mutation Detection Assay (BRAF_476_mu, Life Technologies). Sensitivity testing showed that BRAFV600E variant was detected starting from 6.25X10 -5 ng of DNA, and specificity testing showed that the variant can be detected when diluted in 8X10 5 copies of wild-type alleles. Results: Mutational analysis performed by Sanger sequencing of exon15 in 114 melanoma biopsies showed that 4 (3%) harbored the c.1798_1799GT 〉 AA (V600K) mutation, 1 (1%) the c.1799_1800TG 〉 AA mutation (V600E), and 56 (49%) the most common c.1799T 〉 A mutation (V600E), while by the novel method the latter mutation was detected in 9 additional specimens (8% increment) and confirmed by sequencing the PCR product after TspRI digestion. Pre-surgery plasma was available for 50/114 patients at advanced stages, 26/50 (52%) showing a mutated specimen, including 4 with a double nucleotide substitution (V600K and V600E). The matched plasma samples resulted mutated in 25/26 cases with mutated biopsy and in further 14/25 samples with biopsy resulting wild type; in contrast, plasma of 50 healthy controls tested negative. Taken together, these results indicate that V600E circulating variant was detectable in 39/50 (78%) plasma samples and in 22/50 (44%) tumor specimens. Conclusions: Detection of BRAF V600E variant in circulating free DNA may represent a more sensitive approach for patient selection and decision making process during the treatment with BRAF inhibitors.
Type of Medium:
Online Resource
ISSN:
0732-183X
,
1527-7755
DOI:
10.1200/jco.2013.31.15_suppl.9092
Language:
English
Publisher:
American Society of Clinical Oncology (ASCO)
Publication Date:
2013
detail.hit.zdb_id:
2005181-5
