NGS-Based BRCA1, BRCA2, and PALB2 Mutation Testing in Iranian Population With Breast Cancer

Background: Identification of individuals who have a pathogenic mutation in breast cancer susceptibility genes is an important step to take advantage of genetic counseling, screening, and potentially life-saving prevention strategies. Based on the National Comprehensive Cancer Network (NCCN) guideline, genetic testing is deemed suitable for breast cancer patients with young age at onset, positive family history of cancers, male breast cancer, or diagnosis with a multifocal or triple negative breast cancer. Aim: Since, it is not known what proportion of breast cancers in Iran is hereditary and related to mutations in BRCA1/2 and PALB2 genes, therefore, we screened these 3 genes in multiethnic Iranian population to determine the spectrum of the breast cancer susceptibility gene mutations and to further assess the predictive value of the hereditary breast cancer risk criteria for genetic testing. Methods: Next generation sequencing (NGS) was conducted on a population consisted of 299 and 125 breast cancer patients, with and without hereditary cancer risk criteria for genetic testing, respectively. Results: Pathogenic mutation rate was 10.36% in patients with hereditary criteria for breast cancer vs 1.6% in no criteria group ( P = 0.002). All the patients who only met the young age at onset (<40) criterion tested negative for a gene mutation. This is while patients who had only 1 hereditary criterion (OR: 5.48, 95% CI: 1.09, 52.90, P = 0.017) and patients with multiple hereditary criteria (OR: 22.5, 95% CI: 5.19, 201.31, P < 0.0001) had a significantly higher probability of finding a mutation compared with no risk-criteria group. Conclusion: The first application of NGS on Iranian breast cancer population added to the cumulative evidence that BRCA1/2 mutations are seen commonly among Iranian breast cancer patients especially those with hereditary breast cancer criteria and indicated that PALB2 should be concerned in hereditary breast cancer screening alongside BRCA1/2. Investigating the predictive potential of hereditary breast cancer risk criteria our results suggest that offering genetic testing to women with early age at onset of <40 with no other hereditary criteria, may not be cost effective and should be considered for optimization of genetic counseling and genetic testing of the Iranian population.

Prediction of Response to Irinotecan and Drug Toxicity Based on Pharmacogenomics Test: A Prospective Case Study in Advanced Colorectal Cancer

Background:

FOLFIRI regimen, which is composed of 5-FU, Leucovorin, and Irinotecan, is used in the first-line chemotherapy of metastatic colorectal cancer. Irinotecan life threatening toxicity is partly related to cytotoxic drug metabolite which is primarily inactivated by the UGT1A1 enzyme. The primary aim of the present research was to find the correlation between UGT1A1-genotype and clinical toxicity of irinotecan.

Methods:

In a prospective study from March 2011 to December 2013, all patients with metastatic colorectal cancer who had been referred to Medical Oncology Department of Iran Cancer Institute were genotyped for UGT1A1*28 before the first cycle of chemotherapy. All of the patients signed informed consent and trial approved by Ethics Committee of the Tehran University of Medical Sciences. Reduction of the standard dose of Irinotecan (180 mg/m2 body surface area) was measured based on NCI toxicity criteria after the first cycle of chemotherapy. Patients with previous treatment with Oxaliplatin and fluorouracil (5-FU) in the adjuvant setting and adequate liver, kidney, and heart function were included in the trial. Both synchronous and metachronous metastatic disease were noticeable.

Results:

A total of 50 patients with median age of 52 years were included. Most (70%) of the patients had more than one site of metastases in peritoneum, liver, and/or lung. Thirty-one patients had UGT1A1*1 normal genotype, 13 were in heterozygote and 6 were in homozygote state ofUGT1A1*28/*28. A clinically relevant increase in early toxicity was found in patients carrying the UGT1A1*28/*28 genotype with odds Ratio (OR) of 2.6 (95%CI 2.5-27.28). Similarly, there was a trend of lower overall survival in homozygote group with an HR (Hazardous Ratio) of 2.76 (95%CI .88-.61). No statistically significant relationship was found between UGT1A1genotypes and response to therapy.

Conclusions:

UGT1A1 28*/28* is strongly associated with drug’s life-threatening toxicity even in a moderate dose of Irinotecan. On the other hand, UGT1A1 genotype data was not helpful to differentiate response to treatment.

Expression analysis of microRNA-125 in patients with polycythemia vera and essential thrombocythemia and correlation with JAK2 allele burden and laboratory findings

INTRODUCTION

The JAK2V617F mutation has emerged in recent years as a diagnostic as well as a treatment target in patients with polycythemia vera (PV) and essential thrombocythemia (ET). The disease phenotype is also influenced by other factors such as microRNA (miRNA) deregulation. The aim of this study was to investigate miR-125 expression level in these patients with those obtained from healthy control subjects and its correlation with JAK2 allele burden and laboratory findings.

METHODS

In total, forty patients with a clinical diagnosis of PV and ET were examined at the time of diagnosis. Ten healthy subjects were checked as controls. We performed JAK2 V617F allele burdens measurement and expression analysis of miR-125b-5p, miR-125b-3p, miR-125a-5p, and miR-125a-3p in leukocytes isolated from peripheral blood by quantitative real-time polymerase chain reaction.

RESULTS

MiR-125b-5p and miR-125a-5p were upregulated in both patients with PV (P = 0.00 and P = 0.003, respectively) and ET (P = 0.02 and P = 0.002, respectively). In PV group, a significant correlation was observed between miR-125a-5p and platelet counts (P = 0.01, r = 0.531). The correlation between miRNA and JAk2 allele burden was not significant.

CONCLUSION

In conclusion, our data indicate that other factors such as aberrant miR-125 expression may influence on the disease phenotype in patients with PV and ET.