KRAS and BRAF mutations in anal carcinoma

The EGF receptor (EGFR) is expressed in most cases of anal carcinomas. Anecdotal benefit from EGFR‐targeted therapy has been reported in anal cancer and a negative correlation with Kirsten Ras (KRAS) mutation status has been proposed. The purpose of this retrospective study was to investigate the frequency and the prognostic value of KRAS and BRAF mutations in a large cohort of patients with anal cancer. One hundred and ninety‐three patients with T1‐4N0‐3M0‐1 anal carcinoma were included in the study . Patients were treated with curative (92%) or palliative intent (8%) between January 2000 and January 2010. KRAS mutations were detected using Therascreen^®KRAS real‐time PCR assay (Qiagen) and V600E or V600D/K BRAF mutations were uncovered using Pyrosequencing. The frequency of KRAS and BRAF mutations was low; KRAS mutations were detected in 1.6% and BRAF mutations in 4.7% of the biopsies. No impact of KRAS or BRAF status on survival was found. In conclusion, both KRAS and BRAF mutations are rare in anal cancer. The low frequency of KRAS mutations support protocols exploring EGFR‐targeted therapy in patients with metastatic anal cancer, while treatment with BRAF inhibitors might be relevant for only a very few patients.     

rpoB gene mutations among Mycobacterium tuberculosis isolates from extrapulmonary sites

The aim of this study was to analyze mutations occurring in the rpoB gene of Mycobacterium tuberculosis (MTB) isolates from clinical samples of extrapulmonary tuberculosis (EPTB). Seventy formalin‐fixed, paraffin‐embedded samples and fresh tissue samples from confirmed EPTB cases were analyzed. Nested PCR based on the rpoB gene was performed on the extracted DNAs, combined with cloning and subsequent sequencing. Sixty‐seven (95.7%) samples were positive for nester PCR. Sequence analysis of the 81 bp region of the rpoB gene demonstrated mutations in 41 (61.2%) of 67 sequenced samples. Several point mutations including deletion mutations at codons 510, 512, 513 and 515, with 45% and 51% of the mutations in codons 512 and 513 respectively were seen, along with 26% replacement mutations at codons 509, 513, 514, 518, 520, 524 and 531. The most common alteration was Gln → His, at codon 513, presented in 30 (75.6%) isolates. This study demonstrated sequence alterations in codon 513 of the 81 bp region of the rpoB gene as the most common mutation occurred in 75.6% of molecularly confirmed rifampin‐resistant strains. In addition, simultaneous mutation at codons 512 and 513 was demonstrated in 34.3% of the isolates.     

The prevalence of EGFR mutations in non‐small cell lung cancer in an unselected Caucasian population

EGFR mutation frequencies in unselected Caucasian populations are unknown. This study assesses the prevalence of EGFR mutations in an unselected population‐based cohort, and the correlation between mutation and gender, age, ethnicity, smoking habits, and pathological data. NSCLC patients diagnosed in a well‐defined Danish population were included. The type of the diagnostic material, and data on smoking were registered. The mutation analyses were investigated by Therascreen EGFR RGQ‐PCR Kit or Sanger sequencing. A total of 658 men and 598 women were included. 6.2% were never smokers, 38.9% were ex‐smokers, and 54.9% were current smokers. One thousand one hundred and sixty‐one (92.4%) patients had sufficient material for mutation analysis. Cytological material was used for 38% of the mutation analyses. 5.4% had mutation in the EGFR gene (4.3% men/6.7% women). 87% were activating mutations. 8.0% of adenocarcinomas, and 1.9% of squamous cell carcinomas were mutated. 29.4%, 4.4% and 2.9% of never, ex‐ and current smokers were mutated (p < 0.001). No difference in mutation rate was observed between patients with cytology only, histology only or both cytology and histology available. 5.4% of the patients had EGFR mutation. Adenocarcinomas were mutated more often (8.0%) than squamous cell carcinomas (1.9%). Mutations were found in never smokers as well as in former and current smokers. No difference in gender and age regarding mutation status was observed. EGFR mutations analysis was possible in almost all patients with no difference between cytology and histology specimens.     

Molecular alterations of Ras‐Raf‐mitogen‐activated protein kinase and phosphatidylinositol 3‐kinase‐Akt signaling pathways in colorectal cancers from a tertiary hospital at Kuala Lumpur,Malaysia

Molecular alterations in KRAS, BRAF, PIK3CA, and PTEN have been implicated in designing targeted therapy for colorectal cancer (CRC). The present study aimed to determine the status of these molecular alterations in Malaysian CRCs as such data are not available in the literature. We investigated the mutations of KRAS, BRAF, and PTEN, the gene amplification of PIK3CA, and the protein expression of PTEN and phosphatidylinositol 3‐kinase (PI3K) catalytic subunit (p110α) by direct DNA sequencing, quantitative real‐time PCR, and immunohistochemistry, respectively, in 49 CRC samples. The frequency of KRAS (codons 12, 13, and 61), BRAF (V600E), and PTEN mutations, and PIK3CA amplification was 25.0% (11/44), 2.3% (1/43), 0.0% (0/43), and 76.7% (33/43), respectively. Immunohistochemical staining demonstrated loss of PTEN protein in 54.5% (24/44) of CRCs and no significant difference in PI3K p110α expression between CRCs and the adjacent normal colonic mucosa (p = 0.380). PIK3CA amplification was not associated with PI3K p110α expression level, but associated with male cases (100% of male cases vs 56% of female cases harbored amplified PIK3CA, p = 0.002). PI3K p110α expression was significantly higher (p = 0.041) in poorly/moderately differentiated carcinoma compared with well‐differentiated carcinoma. KRAS mutation, PIK3CA amplification, PTEN loss, and PI3K p110α expression did not correlate with Akt phosphorylation or Ki‐67 expression. KRAS mutation, PIK3CA amplification, and PTEN loss were not mutually exclusive. This is the first report on CRC in Malaysia showing comparable frequency of KRAS mutation and PTEN loss, lower BRAF mutation rate, higher PIK3CA amplification frequency, and rare PTEN mutation, as compared with published reports.     

Multiple and bilateral kidney tumors with clear cells of three different histotypes: A case report with clinicopathologic and molecular study

We describe a rare multicentric neoplastic disease arising bilteraly in the kidney. The patient was a 70‐year‐old man, who, during a period of 3 years, was treated for five independent tumors of three histotypes (three multilocular cystic clear cell renal cell neoplasms of low malignant potential, one clear cell renal cell carcinoma, and one clear cell papillary renal cell carcinoma, respectively). Pathologic diagnosis of the reported tumors was confirmed by immunohistochemical analyses, including CD10, CA IX, CK7, AMACR/RACEMASE, and 34 beta E12. Molecular detection of KRAS, BRAF, NRAS, PIK3CA, ALK, ERBB2, DDR2, MAP2K1, RET, and EGFR gene mutational analysis was also performed in all tumors.