TYMS/KRAS/BRAF molecular profiling predicts survival following adjuvant chemotherapy in colorectal cancer

BACKGROUND Patients with stage II-III colorectal cancer (CRC) treated with adjuvant chemotherapy, gain a 25% survival benefit. In the context of personalized medicine, there is a need to identify patients with CRC who may benefit from adjuvant chemotherapy. Molecular profiling could guide treatment decisions in these patients. Thymidylate synthase (TYMS) gene polymorphisms, KRAS and BRAF could be included in the molecular profile under consideration. AIM To investigate the association of TYMS gene polymorphisms, KRAS and BRAF mutations with survival of CRC patients treated with chemotherapy.METHODS A retrospective study studied formalin-fixed paraffin-embedded tissues (FFPEs) of consecutive patients treated with adjuvant chemotherapy during January/2005-January/2007. FFPEs were analysed with PCR for the detection of TYMS polymorphisms, mutated KRAS (mKRAS) and BRAF (mBRAF). Patients were classified into three groups (high, medium and low risk) according to 5’UTR TYMS polymorphisms Similarly, based on 3’UTR polymorphism ins/loss of heterozygosity (LOH) patients were allocated into two groups (high and low risk of relapse, respectively). Cox regression models examined the associated 5- year survival outcomes. RESULTS One hundred and thirty patients with early stage CRC (stage I-II: 55 patients;stage III 75 patients;colon: 70 patients;rectal: 60 patients) were treated with surgery and chemotherapy. The 5-year disease free survival and overall survival rate was 61.6% and 73.9% respectively. 5’UTR polymorphisms of intermediate TYMS polymorphisms (2RG/3RG, 2RG/LOH, 3RC/LOH) were associated with lower risk for relapse [hazard ratio (HR) 0.320, P = 0.02 and HR 0.343, P = 0.013 respectively] and death (HR 0.368, P = 0.031 and HR 0.394, P = 0.029 respectively). The 3’UTR polymorphism ins/LOH was independently associated with increased risk for disease recurrence (P = 0.001) and death (P = 0.005). mBRAF (3.8% of patients) was associated with increased risk of death (HR 4.500, P = 0.022) whereas mKRAS (39% of patients) not. CONCLUSION Prospective validating studies are required to confirm whether 2RG/3RG, 2RG/LOH, 3RC/LOH, absence of ins/LOH and wild type BRAF may indicate patients at lower risk of relapse following adjuvant chemotherapy.

Integrating TYMS, KRAS and BRAF testing in patients with metastatic colorectal cancer

AIM To investigate the impact of thymidylate synthase(TYMS), KRAS and BRAF in the survival of metastatic colorectal cancer(m CRC) patients treated with chemotherapy. METHODS Clinical data were collected retrospectively from records of consecutive patients with m CRC treated with fluoropyrimidine-based chemotherapy from 1/2005 to 1/2007. Formalin-fixed paraffin-embedded tissues were retrieved for analysis. TYMS genotypes were identified with restriction fragment analysis PCR, while KRAS and BRAF mutation status was evaluated using real-time PCR assays. TYMS gene polymorphisms of each of the 3' untranslated region(UTR) and 5'UTR were classified into three groups according to the probability they have for high, medium and low TYMS expression(and similar levels of risk) based on evidence from previous studies. Univariate and multivariate survival analyses were performed.RESULTS The analysis recovered 89 patients with m CRC(46.1% de novo metastatic disease and 53.9% relapsed). Of these, 46 patients(51.7%) had colon cancer and 43(48.3%) rectal cancer as primary. All patients were treated with fluoropyrimidine-based chemotherapy(5FU or capecitabine) as single-agent or in combination with irinotecan or/and oxaliplatin or/and bevacizumab. With a median follow-up time of 14.8 mo(range 0-119.8), 85 patients(95.5%) experienced disease progression, and 63 deaths(70.8%) were recorded. The 3-year and 5-year OS rate was 25.4% and 7.7% while the 3-year progression-free survival rate was 7.1%. Multivariate analysis of TYMS polymorphisms, KRAS and BRAF with clinicopathological parameters indicated that TYMS 3'UTR polymorphisms are associated with risk for disease progression and death(P < 0.05 and P < 0.03 respectively). When compared to tumors without any del allele(genotypes ins/ins and ins/loss of heterozygosity(LOH) linked with high TYMS expression) tumors with del/del genotype(low expression group) and tumors with ins/del or del/LOH(intermediate expression group) have lower risk for disease progression(HR = 0.432, 95%CI: 0.198-0.946, P < 0.04 and HR = 0.513, 95%CI: 0.287-0.919, P < 0.03 respectively) and death(HR = 0.366, 95%CI: 0.162-0.827, P < 0.02 and HR = 0.559, 95%CI: 0.309-1.113, P < 0.06 respectively). Additionally,KRAS mutation was associated independently with the risk of disease progression(HR = 1.600, 95%CI: 1.011-2.531, P < 0.05). The addition of irinotecan in 1st line chemotherapy was associated independently with lower risk for disease progression and death(HR = 0.600, 95%CI: 0.372-0.969, P < 0.04 and HR = 0.352, 95%CI: 0.164-0.757, P < 0.01 respectively).CONCLUSION The TYMS genotypes ins/ins and ins/LOH associate with worst prognosis in m CRC patients under fluoropyrimidine-based chemotherapy. Large prospective studies are needed for validation of our findings.

Interrogating the interplay of angiogenesis and immunity in metastatic colorectal cancer

Colon cancer is the third most common malignancy and the fifth most frequent cause of death from neoplastic disease worldwide.At the time of diagnosis,more than 20%of patients already have metastatic disease.In the last 20 years,the natural course of the disease has changed due to major changes in the management of metastatic disease such as the advent of novel surgical and local therapy approaches as well as the introduction of novel chemotherapy drugs and targeted agents such as anti-epidermal growth factor receptor,anti-BRAF and antiangiogenics.Angiogenesis is a complex biological process of new vessel formation from existing ones and is an integral component of tumor progression supporting cancer cells to grow,proliferate and metastasize.Many molecules are involved in this proangiogenic process,such as vascular endothelial growth factor and its receptors on endothelial cells.A well-standardized methodology that is applied to assess angiogenesis in the tumor microenvironment is microvascular density by using immunohistochemistry with antibodies against endothelial CD31,CD34 and CD105 antigens.Even smaller molecules,such as the micro-RNAs,which are small non-coding RNAs,are being studied for their usefulness as surrogate biomarkers of angiogenesis and prognosis.In this review,we will discuss recent advances regarding the investigation of angiogenesis,the crosstalk between elements of the immune microenvironment and angiogenesis and how a disorganized tumor vessel network affects the trafficking of CD8+T cells in the tumor bed.Furthermore,we will present recent data from clinical trials that combine antiangiogenic therapies with immune checkpoint inhibitors in colorectal cancer.