Gene expression in tumor-adjacent normal tissue is associated with recurrence in patients with rectal cancer treated with adjuvant chemoradiation

Recurrence is a significant clinical problem for patients with rectal cancer treated with adjuvant chemoradiation. Previous studies have suggested that determining intratumoral gene expression of key genes may be helpful in predicting clinical outcome of patients with gastrointestinal malignancies undergoing chemotherapy. The role of molecular predictors for prediction of recurrence in the setting of adjuvant chemoradiotherapy is not well established. The present study was designed to identify a genetic profile that would be associated with recurrence in patients with rectal cancer treated with adjuvant chemoradiation therapy. A retrospective study with a longitudinal cohort and a cross-sectional cohort of 67 patients with locally advanced rectal cancer who underwent cancer resection, followed by 5-fluorouracil (5-FU) plus pelvic radiation was conducted. Total RNA was extracted from formalin-fixed, paraffin-embedded, laser-captured-microdissected tissue. We determined mRNA levels of genes involved in the 5-FU pathway (thymidylate synthase, dihydropyrimidine dehydrogenase), DNA-repair (excision-repair cross-complementing factor 1, Rad51), angiogenesis/radiation sensitivity [vascular endothelial growth factor (VEGF)] and radio-sensitivity [epidermal growth factor receptor (EGFR)] in tumor tissue and tumor-adjacent normal tissue by quantitative reverse transcriptase-polymerase chain reaction. In univariate analysis, only intratumoral gene expression level of VEGF (P = 0.055) was associated with recurrence, whereas elevated mRNA expression levels of thymidylate synthase (P = 0.008), VEGF (P = 0.023) and EGFR (P = 0.004) in tumor-adjacent normal tissue were significantly associated with recurrence. Multivariate analysis using recursive partitioning indicated that distinct groups of recurrence could be defined by elevated mRNA expression levels of VEGF, EGFR in tumor-adjacent normal tissue, and Rad51 in tumor tissue. These data suggest that the genetic profile of the tumor-adjacent normal tissue may be associated with treatment failure, indicating that tumor microenvironment may be more important in the development of recurrence of rectal tumors than formerly expected.

Tumor VEGFA gene expression is associated with serum lactate dehydrogenase (LDH) levels and intratumoral mRNA expression of genes involved in glycolysis in patients with metastatic colorectal cancer (mCRC)

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Background: It is well known that angiogenesis and glycolysis are regulated by hypoxic conditions. Recent clinical trials (CONFIRM1 and CONFIRM2) have shown that patients with mCRC with high serum LDH benefited from PTK787/ZK 222584, a VEGF receptor tyrosine kinase inhibitor. We tested the hypothesis that patients with high serum LDH have increased intratumoral expression of genes involved with hypoxia (hypoxia inducible factor (HIF1a and 2a) and lactate dehydrogenase A (LDHA) and glycolysis (glucose transporter 1 (Glut-1) and genes involved in angiogenesis such as vascular endothelial growth factor A (VEGFA) and neuropilin 1 (NRP1) in patients with mCRC. Methods: 78 formalin fixed paraffin embedded (FFPE) tumor samples from 36 patients (20 males, 16 females: Median age 59 years (range 29–84) with mCRC who underwent first line therapy (not from CONFIRM trials) were analyzed. In addition, tumor gene expression was correlated with serum LDH levels from the same group of patients. FFPE tissues were dissected using laser-captured microdissection and analyzed LDHA, VEGFA, HIF1a, HIF2a, Glut-1 and NRP1 mRNA expression using a quantitative real-time RT-PCR method. Gene expression values (relative mRNA levels) are expressed as ratios between the target gene and internal reference gene (beta-actin). Results: Spearman Rank Correlation Analysis of Associations Between serum LDH levels and Gene Expression values. Conclusions: Our results demonstrate that intratumoral gene expression of LDHA, HIF1a and HIF2a, Glut-1 and VEGFA are significantly correlated. Patients with high serum LDH have increased intratumoral gene expression of VEGFA. These results support the hypothesis that serum LDH levels may serve as a surrogate marker for activation of the HIF related genes in the tumor. These observations may explain the efficacy of PTK787 in metastatic colorectal cancer patients with high serum LDH levels.

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Intratumoral mRNA levels predict clinical outcome in patients with metastatic colorectal cancer treated in a prospective clinical trial with 5-FU and oxaliplatin

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Background: 5-flurouracil (5-FU) and Oxaliplatin-based therapy is one of the most frequently used combinations in the treatment of advanced colorectal cancer (CRC). There are no validated and established predictive factors for clinical outcome following 5-FU/Oxaliplatin treatment. We had shown an association between intratumoral mRNA levels of TS and ERCC1 involved in 5-FU metabolism and DNA repair, respectively, and survival to 5-FU/Oxaliplatin chemotherapy in advanced CRC in a retrospective study. Now we investigated whether intratumoral mRNA levels of these two genes and others involved in 5-FU metabolism (DPD, TP, dUTPase), DNA repair (ERCC2, XRCC1), angiogenesis (COX-2, EGFR, IL-8, PLA2), and drug detoxification (GSTP-1) predict the clinical outcome of patients with CRC in a prospectively designed biomarker study. Methods: 85 patients with metastatic CRC treated with second-line 5-FU/Oxaliplatin from the prospective trial were included. mRNA levels of 12 genes were assessed from paraffin- embedded tissue samples using laser capture microdissection and quantitative Real-time PCR. Overall survival (OS) was the primary endpoint. Progression-free survival (PFS), response, and toxicity were the secondary endpoints. Results: There were 40 women and 45 men (median age 60 years; range 29–87), median survival of 9.7 ms, median PFS of 4.2 ms, CR in 1 (1%) patient, PR in 15 (18%), SD in 36 (43%) and PD in 32 (38%) patients. High intratumoral mRNA levels of PLA2, TP, GSPTP-1 and low mRNA levels of COX-2 were each significantly associated with shorter OS (P≤0.05, log-rank test). There was a trend in the association between high mRNA levels of PLA2 and shorter PFS (P=0.08). In addition, high mRNA levels of XRCC1 and IL-8 were each significantly associated with high risk of cumulative grade 3+ toxicity (P≤0.05). No significant association was found between mRNA levels and response to 5-FU/Oxaliplatin. Conclusions: This study suggests that mRNA levels of PLA2, TP, GSTP-1, COX-2, XRCC1, and IL-8 may be useful to predict the outcome of patients with metastatic CRC with second-line 5-FU/Oxaliplatin chemotherapy. These findings should be validated with future basic sciences studies and prospective clinical trials.

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Polymorphism in sodium-channel alpha 1-subunit (SCN1A) predicts response, TTP, survival, and toxicity in patients with metastatic colorectal cancer treated with 5-FU/oxaliplatin

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Background: Genetic polymorphisms in DNA repair and drug metabolism pathways have been shown to be associated with efficacy and toxicity in patients with metastatic colon cancer treated with 5-FU/oxaliplatin. Recent studies demonstrated in in vitro models that the neurotoxicity associated with oxaliplatin may be linked to an effect on neuronal voltage-gated sodium channels (VGSC). In vitro and in vivo models showed that increased VGSC alpha gene expression was associated with metastatic potential, proliferation and progression of breast and prostate cancer indicating a role in predicting toxicity and efficacy to chemotherapy. We tested the hypothesis whether VGSC gene polymorphisms may predict clinical outcome in a phase II study of combination oxaliplatin with 5-FU in patients with colorectal cancer refractory to 5-FU and/or irinotecan based chemotherapy. Methods: 173 patients were enrolled in this phase II study. 152 patients (male/female; 78/74, median age; 60), median follow up of 18.6 months, response rate of 19%, median time to tumor progression 4.2 months and median survival of 10.3 months. Grade 3/4 toxicity was seen in 60% with GI toxicity of 42% and Neurotoxicity of 11%. The dose of oxaliplatin was 130mg/m2 every 3 weeks and 5-FU was 200mg/m2/day CI for 10 weeks followed by 2 weeks rest. We tested the 12 VGSC genes polymorphisms (SCN1A, 1B, 1A1, 1A2, 1A3, 1A4, 1A5, 1A A3169G SNP, 1A C1702T Nonsense Mutation, 1A T1067A SNP, 1A C3637T SNP, SCN8A Ref SNP 303802). Genomic DNA was extracted from peripheral blood samples and polymorphisms were analyzed by PCR-based RFLP technique. Results: Patients with SCN1A T1067A SNP T/T genotype showed a significant better response rate (p=0.02, 21.9% [23/105] vs. 11.3% [5/44]), TTP (p=0.02, 4.6 months vs. 3.4 months), overall survival (p<.001, 12.3 months. vs. 8.0 months.), and frequency of grade 3/4 toxicity (p=.002) compare to patients with T/A genotype. No A/A genotype was observed. Conclusions: SCN1A gene polymorphism may be potential molecular marker for survival and toxicity in patients with colorectal cancer treated with 5-FU/oxaliplatin. In vitro studies are ongoing to identify the mechanism of resistance by SCN1A.

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