High resolution melting analysis of KRAS, BRAF and PIK3CA in KRASexon 2 wild-type metastatic colorectal cancer

7075 Background: Recent studies have shown that EGFR mutations, mainly deletions in exon 19 (DEL) and L858R, are associated with gefitinib sensitivity in patients (pts) with NSCLC. We established a new easy method, using high-resolution melting analysis (HRMA), for detecting DEL and L858R mutations even from small biopsy or cytology samples, and evaluated the significance of EGFR mutations in NSCLC on a larger scale. Methods: Among 364 advanced or recurrent NSCLC pts treated with gefitinib between Jul 2002 and Dec 2004, HRMA was performed in 207 pts from whom specimens were available. DNA extracted from the archival tissue or cytology samples not subjected to microdissection was analyzed to detect DEL and L858R using HR-1 (Idaho Technology), an HRMA device. To validate this method, the results were compared with direct sequencing data obtained from microdissected tumor cells from surgical specimens in 66 pts. Results: Tissue/cytology/both samples were analyzed in 91/77/39 pts. EGFR mutations were detected in 85 (41%; DEL/L858R: 49/36) of the 207 pts. In the comparison with direct sequencing, consistent results were obtained from all of the 66 tissue samples, while false negative results were obtained in 2 of the 28 cytology samples. EGFR mutations were seen more frequently in women (54% vs. 31%; P = .001), never-smokers (53% vs. 32%; P = .002), and pts with adenocarcinoma (44% vs. 11%; P = .007). CR/PR/SD/PD was observed in 2/64/11/8 pts with EGFR mutations and in 0/10/23/89 pts with wild-type EGFR. The response rate (78% vs. 8%), time to progression (median, 9.1 vs. 1.6 months) and overall survival (median, 19.9 vs. 9.1 months) were all significantly superior in pts with EGFR mutations (P < .0001). Minor response and/or long SD (>6 months) was observed more frequently in SD pts with EGFR mutations than in those with wild-type EGFR (91% vs. 26%; P < .001). Among the pts with EGFR mutations, the response rate was significantly higher in the pts with DEL than in those with L858R (86% vs. 67%; P = .037). Conclusions: HRMA is a practical and precise method to detect DEL and L858R mutations. EGFR mutations strongly predict a better response and longer survival in NSCLC pts treated with gefitinib. No significant financial relationships to disclose.

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SLCO1B3 screening in colorectal cancer patients using High-Resolution Melting Analysis method and immunohistochemistry

Tumor Biology ◽

10.1177/1010428317691176 ◽

2017 ◽

Vol 39 (3) ◽

pp. 101042831769117 ◽

Cited By ~ 2

Author(s):

Lampri Evangeli ◽

Sainis Ioannis ◽

Kounnis Valentinos ◽

Mitselou Antigony ◽

Ioachim Elli ◽

...

Keyword(s):

Colorectal Cancer ◽

High Resolution ◽

Cancer Patients ◽

High Resolution Melting ◽

Organic Anion ◽

High Resolution Melting Analysis ◽

Organic Anion Transporting Polypeptide ◽

Melting Analysis ◽

Colorectal Cancer Patients ◽

Gene Alterations

Personalized medicine has made some major advances in colorectal cancer, but new biomarkers still remain a hot issue as an emerging tool with potential prognostic and therapeutic potential. We investigated for SLCO1B3 gene alterations and protein expression in colorectal cancer, using the novel high-resolution melting analysis technique and immunohistochemistry. Formalin-fixed paraffin-embedded tumor samples from 30 colorectal cancer patients were used. The screening for gene alterations was done by high-resolution melting analysis for all exons of SLCO1B3 gene. Organic anion-transporting polypeptide 1B3 protein expression was assessed by immunohistochemistry using the monoclonal mouse MDQ antibody. High level of polymorphism was observed in the SLCO1B3 gene. We identified three previously reported polymorphisms in exons 7, 12, and 14, 699G>A, 1557A>G, and 1833G>A, respectively. In the exon 5, one variant seems to correspond to an as yet unknown SLCO family member. The immunohistochemical study revealed that organic anion-transporting polypeptide 1B3 was expressed in 27/30 samples. Of great interest, the three samples, which were immunohistochemically negative, all appeared to accommodate mutations which lead to either early stop codons or other conformations of the tertiary protein structures affecting the antibody-epitope binding. The results of this study are of much interest as high-resolution melting analysis proved to be a reliable and rapid genotyping/scanning method for mutation detection of SLCO1B3 gene.

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