ERCC1 as a Predictive Marker for FOLFOX Chemotherapy in an Adjuvant Setting

ERCC1 and MGMT Methylation as a Predictive Marker of Relapse and FOLFOX Response in Colorectal Cancer Patients from South Tunisia

Genetic and epigenetic modifications present a major cause of relapse and treatment failure in colorectal cancer. This study aims to appreciate the prognostic and predictive value of ERRC1 and MGMT methylation. We also studied the prognostic impact of the ERCC1 rs11615 polymorphism as well as its expression. Methylation profiles of ERCC1 and MGMT were tested by methylation-specific PCR. A polymorphism of ERCC1 was studied using PCR-RFLP and its expression was examined by immunohistochemistry. ERCC1 was methylated in 44.6% of colorectal adenocarcinoma while MGMT was methylated in 69% of cases. MGMT methylation was strongly associated with lymph node metastasis, lymph invasion, venous invasion, perineural invasion, distant metastasis and relapse. Patients with methylation of both genes were more likely to have a poor prognosis and display chemoresistance. IHC analysis revealed that ERCC1 staining was noted in 52.8% of colorectal adenocarcinoma and inversely related to distant metastasis and cancer recurrence. Kaplan Meier analysis revealed that the worst overall survival was significantly associated with ERCC1 and MGMT methylation while decreased ERCC1 expression and T/T genotype exhibited the best overall survival. The methylation of MGMT, alone or combined with ERCC1, is predictive for poor prognosis, short overall survival and chemotherapy response in colorectal cancer.

ERCC1, PARP-1, and AQP1 as predictive biomarkers in colon cancer patients receiving adjuvant chemotherapy

BACKGROUND

The recognition of high-risk colon cancer patients prone to chemoresistant and recurrent disease is a challenge.

OBJECTIVES

We aimed to assess the immunohistochemical expression of ERCC1, PARP-1, and AQP1 in 60 cases of stage II and III colon cancer who underwent curative resection and adjuvant chemotherapy. Their predictive role of tumor progression and disease-free survival (DFS) was analyzed.

METHODS

The immunohistochemical expression of ERCC1, PARP-1, and AQP1 in 60 cases of stage II and III colon cancer who underwent curative resection and adjuvant chemotherapy was studied. The collected data on the overall survival (OS), disease-free survival (DFS), and the response to the chemotherapy were analyzed.

RESULTS

Positive nuclear ERCC1 expression was identified in 58.3% of the patients, ERCC1 expression was significantly associated with left-sided tumors (P< 0.01). Moreover, its expression was significantly associated with the aggressive tumor characteristics including high grade, lymph node metastasis and advanced tumor stage (P< 0.001 for each). High nuclear PARP-1 expression was observed in 63.3% of the cases, and its expression was significantly associated with tumor grade and lymph node metastasis (P= 0.003 for each). Positive membranous AQP1 expression was identified in 41.7% of patients, and it was associated with high grade, lymph node metastasis and advanced tumor stage (P< 0.001 for each). During the follow-up period, 23 patients (38.3%) exhibited a tumor progression; this was significantly associated with positive ERCC1, high PARP-1, and negative AQP1 expression. Statistics of the survival data revealed that shorter DFS was significantly associated with positive ERCC1, high PARP-1, and positive AQP1 expression (P= 0.005, 0.016, 0.002, respectively).

CONCLUSIONS

ERCC1, PARP1, and AQP1 are adverse prognostic biomarkers in stage II-III colon cancer. Moreover, adjuvant chemotherapy may not be beneficial for patients with positive ERCC1, high PARP1, and AQP1-negative tumors. Therefore, we recommend that ERCC1, PARP-1, and AQP1 should be assessed during the selection of the treatment strategy for stage II-III colon cancer patients.

Using patient-derived xenograft models of colorectal liver metastases to predict chemosensitivity

BACKGROUND

Few in vivo models for colorectal cancer have been demonstrated to show external validity by accurately predicting clinical patient outcomes. Patient-derived xenograft (PDX) models of cancer have characteristics that might provide a form of translational research leading to personalized cancer care. The aim of this pilot study was to assess the feasibility of using PDXs as a platform for predicting patient colorectal liver metastases responses, in this case by correlating PDX and patient tumor responses to either folinic acid, fluorouracil plus oxaliplatin or folinic acid, fluorouracil plus irinotecan-based regimens.

METHODS

Sixteen patients underwent potentially curative resection of colorectal liver metastases, and tumors were grafted into NOD.CB17-Prkdc^scid/Arc mice. Mice were divided into groups to determine relative tumor growth in response to treatment. Tumors were analyzed by immunohistochemistry for Ki67 and Excision repair cross-complementation group 1.

RESULTS

An engraftment rate of 81% was achieved. Overall, there was a 67% positive match rate between eligible patient and PDX chemosensitivity profiles. There was a significant difference in relative decrease in Ki67 expression between sensitive/stable versus resistant PDXs for both treatment regimens. There was no statistically significant correlation between baseline ERCC1 expression and response to Oxaliplatin + 5-Fluorouracil in the PDXs.

CONCLUSIONS

This pilot study supports the feasibility of using PDX models of advanced colorectal cancer in larger studies to potentially predict patient chemosensitivity profiles.

Predictive Biomarkers in Colorectal Cancer: From the Single Therapeutic Target to a Plethora of Options

Colorectal cancer (CRC) is one of the most frequent cancers and is a leading cause of cancer death worldwide. Treatments used for CRC may include some combination of surgery, radiation therapy, chemotherapy, and targeted therapy. The current standard drugs used in chemotherapy are 5-fluorouracil and leucovorin in combination with irinotecan and/or oxaliplatin. Most recently, biologic agents have been proven to have therapeutic benefits in metastatic CRC alone or in association with standard chemotherapy. However, patients present different treatment responses, in terms of efficacy and toxicity; therefore, it is important to identify biological markers that can predict the response to therapy and help select patients that would benefit from specific regimens. In this paper, authors review CRC genetic markers that could be useful in predicting the sensitivity/resistance to chemotherapy.