Total circulating cell-free DNA as a prognostic biomarker in metastatic colorectal cancer before first-line oxaliplatin-based chemotherapy.

BACKGROUND: Metastatic colorectal cancer (mCRC) is a heterogeneous disease where prognosis is dependent both on tumor biology and host factors. Total circulating cell-free DNA (cfDNA) has shown to harbor prognostic information in mCRC, although less is known about the biological correlates of cfDNA levels in this patient group. The primary objective was to evaluate the prognostic value of pretreatment cfDNA in patients receiving the first-line oxaliplatin-based chemotherapy for mCRC, by using a predefined upper limit of normal (ULN) from a cohort of presumed healthy individuals. The secondary objective was to model cfDNA levels as a function of predefined tumor and host factors. PATIENTS AND METHODS: This was a retrospective post hoc study based on a prospective multicenter phase III trial, the NORDIC-VII study. DNA was purified from 547 plasma samples and cfDNA quantified by a droplet digital PCR assay (B2M, PPIA) with controls for lymphocyte contamination. Main clinical end point was overall survival (OS). RESULTS: cfDNA was quantified in 493 patients, 54 were excluded mainly due to lymphocyte contamination. Median cfDNA level was 7673 alleles/ml (1050-1 645 000) for B2M and 5959 alleles/ml (555-854 167) for PPIA. High cfDNA levels were associated with impaired outcome; median OS of 16.6 months for levels above ULN and 25.9 months for levels below ULN (hazard ratio = 1.83, 95% confidence interval 1.51-2.21, P < 0.001). The result was confirmed in multivariate OS analysis adjusting for established clinicopathological characteristics. A linear regression model predicted cfDNA levels from sum of longest tumor diameters by RECIST, the presence of liver metastases and systemic inflammatory response as measured by interleukin 6 (F(6, 357) = 62.7, P < 0.001). CONCLUSION: cfDNA holds promise as a minimally invasive and clinically relevant prognostic biomarker in mCRC before initiating first-line oxaliplatin-based chemotherapy and may be a complex entity associated with tumor burden, liver metastases and systemic inflammatory response. TRIAL REGISTRATION: ClinicalTrials.gov, NCT00145314.

The correlation between cell-free DNA and tumour burden was estimated by PET/CT in patients with advanced NSCLC.

BACKGROUND: Cell-free DNA (cfDNA) circulating in the blood holds a possible prognostic value in malignant diseases. Under malignant conditions, the level of cfDNA increases but the biological mechanism remains to be fully understood. We aimed to examine the correlation between cfDNA and total tumour burden defined by positron emission tomography (PET) parameters. METHODS: Patients with advanced non-small cell lung cancer (NSCLC) were enrolled into a prospective biomarker trial. Before treatment, plasma was extracted and the level of cfDNA was determined by qPCR. An (18)F-fluorodeoxyglucose ((18)F-FDG) PET/computed tomography (CT) scan was performed and evaluated in terms of metabolic tumour volume (MTV) and total lesion glycolysis (TLG). Tumour contours were delineated semi-automatically by a threshold standardised uptake value (SUV) of 2.5. The primary end point was correlation among cfDNA, MTV and TLG. The secondary end point was overall survival (OS) according to cfDNA, MTV and TLG. RESULTS: Fifty-three patients were included. There were no correlations between cfDNA and MTV (r=0.1) or TLG (r=0.1). cfDNA >75th percentile was correlated with shorter OS (P=0.02), confirmed in a multivariate analysis. MTV>the median was associated with a significantly shorter OS (P=0.02). There was no significant difference in OS according to TLG (P=0.08). CONCLUSION: Cell-free DNA may not be a simple measure of tumour burden, but seems to reflect more complex mechanisms of tumour biology, making it attractive as an independent prognostic marker.

The relationship between serum vascular endothelial growth factor A and microsatellite instability in colorectal cancer.

AIM: It has been suggested that colorectal neoplasms with or without microsatellite instability (MSI) can stimulate angiogenesis in different ways. The vascular endothelial growth factor (VEGF) system is essential for the angiogenetic process and the growth of malignant tumours. The aim of this study was to analyse the relationship between serum VEGF-A and the MSI status of patients with colorectal cancer (CRC). METHOD: In the study, 249 patients with CRC were divided into a test cohort of 83 patients and a validation cohort of 166. MSI was determined using immunohistochemistry. Tumours lacking protein expression of any of the four mismatch repair genes (MLH1, PMS2, MSH2 or MSH6) were labelled as high MSI. The rest were considered to be microsatellite stable (MSS). The serum VEGF-A analyses were performed by ELISA. RESULTS: The tumours of 15 patients in the test cohort and 27 in the validation cohort were classified as MSI. In the test cohort, patients with an MSI tumour had a significantly higher median serum VEGF-A concentration [617 pg/ml (95% CI 445-863)], compared with patients with an MSS tumour, [317 pg/ml (95% CI 224-386)], P = 0.01. A similar relationship was confirmed in the validation cohort, P = 0.04. CONCLUSION: This study provides some evidence to suggest that patients with an MSI tumour have higher serum VEGF-A levels than patients with an MSS tumour. If further validated, these findings could be of importance when considering the effects of anti-VEGF-A treatment.

EGF61A>G polymorphism as predictive marker of clinical outcome to first-line capecitabine and oxaliplatin in metastatic colorectal cancer.

BACKGROUND: The purpose of the present study was to investigate polymorphisms related to the metabolism of fluoropyrimidine and oxaliplatin, thymidylate synthase (TS) and excision repair cross-complementing gene 1 (ERCC1) 118, in metastatic colorectal cancer patients treated with capecitabine and oxaliplatin (XELOX). We also investigated the importance of the EGF61A>G polymorphism, which holds a functional influence on the tyrosine kinase receptor regulation. MATERIALS AND METHODS: We included 68 patients treated with first-line XELOX. Polymorphism analyses were carried out on pretreatment blood samples. Response was evaluated according to the RECIST. Survival analysis was described by the Kaplan-Meier method and log-rank testing. RESULTS: The overall response rate was 38% and the median overall survival 19.4 months. A favorable outcome was seen in patients with the EGF61A/G genotype compared with the combined group of A/A and G/G, with response rates of 57% and 18%, respectively (P = 0.001). There was a significantly different progression-free survival (P = 0.018) in favor of the A/G group. The TS and ERCC1 genotypes failed to provide any significant impact on the outcome. CONCLUSION: Polymorphism analysis of a simple blood sample is a feasible approach to biomarker analysis and the EGF61A>G polymorphism may influence the effect of first-line XELOX. Consequently, this marker deserves further investigation.

The prognostic value of lymph node metastases and tumour regression grade in rectal cancer patients treated with long-course preoperative chemoradiotherapy.

OBJECTIVE: The purpose of the present study was to investigate the impact of tumour regression and the post-treatment lymph node status on the prognosis of rectal cancer treated by preoperative neoadjuvant chemoradiotherapy. METHOD: One hundred and thirty-five patients with locally advanced T3 and T4 rectal tumours received preoperative long-course chemoradiation, to a dose of 60 Gy external radiation and oral 5-fluorouracil 300 mg/m(2) daily and Leukovorin 22.5 mg/day 5 days a week. Surgery was performed 8 weeks after the end of treatment. The tumour response was evaluated according to the tumour regression grade system and lymph node status in the surgical specimen was assessed. The prognostic value of clinico-pathological parameters was analysed using univariate analysis and Kaplan-Meier methods for comparison of groups. RESULTS: All patients responded to treatment and 47% had a major response, including 25 (19%) complete responders. The median follow-up was 26 months (range 12-94 months). The cancer specific survival was 82% and there was a significant lower survival rate in the group of patients with post-treatment lymph node metastases compared to lymph-node negative patients [63% and 87% respectively (P = 0.007)]. Furthermore patients with a major tumour response and no lymph node metastases in the surgical specimen after treatment had a survival rate of 100% compared with 60% in the group of patients with major response but lymph node metastases after surgery (P < 0.01). CONCLUSION: The combined assessment of lymph-node status and tumour response has strong prognostic value in locally advanced rectal cancer patient treated with preoperative long-course chemoradiation.