Genetic mutations in HER2-positive breast cancer: possible association with response to trastuzumab therapy.

BACKGROUND: HER2-positive breast cancer occurs in 15-20% of breast cancer patients and is characterized by poor prognosis. Trastuzumab is considered the key drug for treatment of HER2-positive breast cancer patients. It improves patient survival; however, resistance to trastuzumab remains a challenge in HER2-positive breast cancer patients. Therefore, the prediction of response to trastuzumab is crucial to choose optimal treatment regimens. The aim of the study was to identify genetic variants that could predict response to anti-HER2-targeted therapy (trastuzumab) using next-generation sequencing. METHOD: Genetic variants in the hotspot regions of 17 genes were studied in 24 Formalin-Fixed Paraffin-Embedded (FFPE) samples using Ion S5 next-generation sequencing system. FFPE samples were collected from HER2­positive breast cancer patients previously treated with anti­HER2­targeted treatment (Trastuzumab). Patients were divided into two groups; trastuzumab-sensitive group and trastuzumab-resistant group based on their response to targeted therapy. RESULTS: We identified 29 genetic variants in nine genes that only occurred in trastuzumab-resistant patients and could be associated with resistance to targeted therapy including TP53, ATM, RB1, MLH1, SMARCB1, SMO, GNAS, CDH1, and VHL. Four variants out of these 29 variants were repeated in more than one patient; two variants in TP53, one variant in ATM gene, and the last variant in RB1 gene. In addition, three genes were found to be mutated only in resistant patients; MLH1, SMARCB1 and SMO genes. Moreover, one novel allele (c.407A > G, p. Gln136Arg) was detected within exon 4 of TP53 gene in one resistant patient. CONCLUSION: NGS sequencing is a useful tool to detect genetic variants that could predict response to trastuzumab therapy.

Investigation of a Possible Association Between Refractory Iron Deficiency Anaemia to an Underlying Remote Helicobacter pylori Infection.

UNLABELLED: Helicobacter pylori is a bacterial infection accounts as the prevalent gastric pathogen. Helicobacter has been associated with many extradigestive disorders, as refractory iron deficiency anaemia (Sideropenic). The aim of this case control study was to investigate the role of remote Helicobacter pylori infection in refractory iron deficiency anaemia (RIDA); together with comparing two different methods for diagnosis of Helicobacter pylori infection. The study was conducted on thirty patients proved refractory IDA by therapeutic trial. Thirty normal non anaemic subjects were included as controls. Helicobacter pylori testing included stool antigen and Helicobacter pylori PCR. The Helicobacter pylori stool antigen test revealed 12 positive cases out of 30 IDA cases. Five of them were stool PCR cagA positive and four were stool PCR ureC positive. There was 100% agreement between PCR cagA and the stool antigen test in the detection of Helicobacter pylori infection (p= 0.003). Stool PCR cagA had a diagnostic accuracy of 76.67 and likelihood ratio of 3.57. There was 100% agreement between PCR ureC and the stool antigen test in the detection of Helicobacter pylori infection (p= 0.009). Stool PCR ureC had a diagnostic accuracy of 73.33 and likelihood ratio of 3.25. There was a very highly significant difference between the means of serum ferritin, serum iron, TIBC and transferrin saturation of Helicobacter pylori stool antigen positive and negative subjects (p<0.001). CONCLUSION: There was a very highly significant association between Helicobacter pylori infection and refractory iron deficiency anaemia. Serum ferritin levels were significantly lower in Helicobacter pylori stool antigen positive cases than in negative cases (p< 0.001). Helicobacter pylori positive cases were 2.7 times more likely to develop anaemia than negative cases. The Helicobacter pylori stool antigen testing by ELISA proved to be more reliable compared to the stool PCR which is tedious and time consuming.