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KRAS and BRAF mutation status in circulating colorectal tumor cells and their correlation with primary and metastatic tumor tissue
Author(s) -
Mostert Bianca,
Jiang Yuqiu,
Sieuwerts Anieta M.,
Wang Haiying,
Boltde Vries Joan,
Biermann Katharina,
Kraan Jaco,
Lalmahomed Zarina,
Galen Anne,
Weerd Vanja,
Spoel Petra,
RamírezMoreno Raquel,
Verhoef Cornelis,
IJzermans Jan N.M.,
Wang Yixin,
Gratama JanWillem,
Foekens John A.,
Sleijfer Stefan,
Martens John W.M.
Publication year - 2013
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.27987
Subject(s) - kras , circulating tumor cell , colorectal cancer , primary tumor , cancer research , mutation , medicine , sanger sequencing , metastasis , liquid biopsy , cancer , oncology , biology , gene , biochemistry
Although anti‐EGFR therapy has established efficacy in metastatic colorectal cancer, only 10‐20% of unselected patients respond. This is partly due to KRAS and BRAF mutations, which are currently assessed in the primary tumor. To improve patient selection, assessing mutation status in circulating tumor cells (CTCs), which possibly better represent metastases than the primary tumor, could be advantageous. We investigated the feasibility of KRAS and BRAF mutation detection in colorectal CTCs by comparing three sensitive methods and compared mutation status in matching primary tumor, liver metastasis and CTCs. CTCs were isolated from blood drawn from 49 patients before liver resection using CellSearch™. DNA and RNA was isolated from primary tumors, metastases and CTCs. Mutations were assessed by co‐amplification at lower denaturation temperature‐PCR (Transgenomic™), real‐time PCR (EntroGen™) and nested Allele‐Specific Blocker (ASB‐)PCR and confirmed by Sanger sequencing. In 43 of the 49 patients, tissue RNA and DNA was of sufficient quantity and quality. In these 43 patients, discordance between primary and metastatic tumor was 23% for KRAS and 7% for BRAF mutations. RNA and DNA from CTCs was available from 42 of the 43 patients, in which ASB‐PCR was able to detect the most mutations. Inconclusive results in patients with low CTC counts limited the interpretation of discrepancies between tissue and CTCs. Determination of KRAS and BRAF mutations in CTCs is challenging but feasible. Of the tested methods, nested ASB‐PCR, enabling detection of KRAS and BRAF mutations in patients with as little as two CTCs, seems to be superior.