KRAS and BRAF mutations in Serbian patients with colorectal cancer.

PURPOSE: Mutations of KRAS and BRAF genes represent molecular biomarkers of response to targeted therapy in patients with metastatic colorectal cancer (mCRC). Since these mutations have been shown to exert different biological effects and impacts on patients' outcome, there is a need to determine reliably the frequency and types of KRAS mutations for diagnostic and individual therapeutic purposes. Despite having a wild type (wt) KRAS, some patients fail to respond to treatment. BRAF V600E mutation is an additional molecular determinant of response to the same therapy. In this study we described the KRAS and the BRAF V600E mutation spectra and frequencies in a group of Serbian mCRC specimens. METHODS: KRAS mutations were determined with DxS TheraScreen® K-RAS Mutation Kit and KRAS StripAssay(™), and for the BRAF V600E mutation we applied High Resolution Melting (HRM) analysis. RESULTS: KRAS mutations were present in 34.7% of 190 analyzed samples. The 7 most frequent mutation types observed were: G12D 43.9%, G12V 21.2%, G12A 10.6%, G12C 7.6%, G12S 4.5%, G12R 1.5%, G13D 10.6%. Among the wt KRAS patients, 17.8% carried the BRAF V600E mutation. CONCLUSIONS: We have shown that the spectrum and frequency distribution of the identified KRAS and BRAF mutations in Serbian study population are in good accordance with literature data. We believe that our results are significant concerning aspects related to tumor molecular biology as well as to patient selection in the diagnostic settings.

TP53 gene status and human papilloma virus infection in response to platinum plus taxane-based chemotherapy of epithelial ovarian carcinomas.

PURPOSE: Lack of symptoms in early stages of disease and resistance to chemotherapy make epithelial ovarian carcinomas one of the most lethal neoplasms among gynaecological malignancies. The aim of this study was to analyse the impact of TP53 mutations, codon 72 polymorphism and human papillomavirus (HPV) infection on the response to platinum-taxane combination chemotherapy in patients with epithelial ovarian carcinomas. METHODS: The study was conducted on 26 ovarian carcinoma patients who received carboplatin plus paclitaxel combination chemotherapy. DNA was isolated by salting-out procedure. Mutations in exons 4-8 of TP53 gene were detected by PCR-SSCP and confirmed by automatic DNA sequencing. Codon 72 polymorphism was assessed by the RFLP method. HPV infection was detected through amplification of one part of L1 viral gene. Genotyping was performed by DNA sequencing. Fisher's exact and log-rank tests were used for statistical analysis. RESULTS: TP53 mutations were present in 5/26 (19.2%) ovarian carcinomas. The distribution of codon 72 TP53 genotypes was: Arg/Arg 38.5%, Arg/Pro 50.0%, Pro/Pro 11.5%. HPV was present in 4/26 (15.4%) ovarian carcinomas. All HPV-positive tumors were HPV16 type. Patients with mutations in TP53 gene, Arg/Arg genotype of codon 72 and absence of HPV infection experienced the highest tumor response rate to platinum-taxane chemotherapy. However, no significant correlation between progression free interval (PFI) and the examined biomarkers was observed. CONCLUSION: Our results indicate that, based on the TP53 gene status and the presence/absence of HPV infection, the subgroups of patients having better initial response to platinum-taxane therapy could be distinguished. This might contribute to more adequate treatment and individual therapeutic approach.

p53 gene mutations and codon 72 polymorphism in ovarian carcinoma patients from Serbia.

PURPOSE: Ovarian cancer is the leading cause of death from gynecological malignancies. The early stages of this disease are asymptomatic and more than 75% of the cases are diagnosed with regional or distant metastases. p53 gene is frequently mutated in some histological subtypes of ovarian carcinomas. The role of p53 mutations and polymorphic variant of codon 72 in the prognosis of disease is still unclear. The aim of this study was to determine the frequency of p53 mutations and polymorphic variants of codon 72 among ovarian carcinoma patients and to correlate them with clinicopathological characteristics of disease. METHODS: 54 ovarian carcinoma patients were included in the study. DNA was isolated from tumor tissue by the salting- out method. p53 mutations in exons 4-8 were detected by PCR-SSCP (polymerase chain reaction - single-stranded conformational polymorphism) electrophoresis. Codon 72 polymorphism was assessed by RFLP (restriction fragment-length polymorphism) method. RESULTS: p53 mutations were present in 11 out of 54 patients (20.4%). Twenty-four patients (44.4%) exhibited Arg/ Arg, 24 patients (44.4%) Arg/Pro and 6 patients (11.2%) Pro/ Pro genotype of 72 codon polymorphism. Correlations between p53 mutations and various clinicopathological characteristics were not found. However, we observed that the frequency of Pro/Pro genotype was increasing with higher histological grade as well as in advanced compared to localized disease, but without statistical significance. Distribution of p53 gene mutations between Pro/Pro genotype and Arg/Pro plus Arg/Arg genotypes was not statistically significant. CONCLUSION: Our study suggests that Pro/Pro genotype of 72 codon polymorphism could be an independent prognostic marker in ovarian carcinomas.

Therapeutic cancer vaccines in cervical cancer: phase I study of Lovaxin-C.

Producing effective therapeutic vaccines has proved much more difficult and challenging than developing cancer preventive vaccines. Despite huge research in the area of cancer immunology, FDA/EMEA have not approved any type of cancer treatment vaccine so far. More than 99% of cervical cancers have detectable amounts of human papillomavirus (HPV) DNA. Integration of high-risk HPV into the host cell genome is followed by continual expression of HPV E6 and E7 oncoproteins, making them excellent targets for developing vaccines which could be used in high grade precancerous (CIN) lesions or invasive cancer or in the prevention of cancer recurrence. Therapeutic cervical cancer vaccines have been extensively studied. Strategies used were vaccination with HPV peptides or proteins, alone or in pulsed dendritic cells, DNA vaccines, virus-like particles or viral and bacterial vectors. Lovaxin-C is a recombinant live-attenuated Listeria monocytogenes (Lm) that secretes the antigen HPV-16 E7 fused to a non-hemolytic listeriolysin O protein. In a phase I study Lovaxin-C was administered to advanced cervical cancer patients refractory to existing therapies. The dose-limiting toxicity was hypotension and flue-like syndrome. There were no serious adverse events. Specific T-cell response was detected as well as clinical response to Lovaxin-C. Several other therapeutic HPV vaccines are in clinical development and in most of the studies specific immunological and clinical responses were seen. Efficacious therapeutic vaccine for the treatment of cervical cancer should be expected in the near future.

p53 gene alterations and human papillomavirus type 16 infection in early stages of cervical carcinoma in Serbia.

PURPOSE: The incidence rate (age-standardized) of cervical carcinoma in Serbia is the highest in Europe. p53 is mainly inactivated at protein level in carcinomas associated with human papillomavirus (HPV) infection, such as cervical carcinomas. These tumors show low rate of p53 mutations. It is not clear if p53 mutations confer additional impact on disease prognosis. The role of polymorphic variant at codon 72 of p53 gene on patient's prognosis is controversial. The aim of this study was to determine the frequency of p53 mutations and to assess polymorphic variants of codon 72 among cervical carcinoma patients. PATIENTS AND METHODS: 53 patients, mainly FIGO stage I (n=50), with squamous cell carcinoma (n=49) were included. 30/32 (94%) patients who received adjuvant radiotherapy were followed-up (median 15 months, range 4-39). DNA was isolated by the salting out method from tumor tissue (n=53) and blood (42/53). p53 mutations were detected by PCR-SSCP (polymerase chain reaction - single-stranded conformational polymorphism) electrophoresis. Codon 72 polymorphism was assessed by the restriction fragment-length polymorphism method. RESULTS: Six p53 mutations were detected in 5/53 (9%) patients with FIGO stage I squamous cell carcinoma (one patient had double mutations). 25/42 (60%) patients exhibited Arg/Arg genotype. HPV16 type was detected in 29/51 (57%) cervical carcinoma samples. Relapse of disease occurred in only 2 patients- both with Arg/Arg genotype and HPV16 positive. One of them exhibited p53 mutation. CONCLUSION: Our results showed low incidence of p53 mutations and prevalence of Arg/Arg genotype polymorphic variant of codon 72 of p53 gene in early stages of cervical carcinoma.