Molecular markers predictive of response to chemotherapy in gastrointestinal tumors

Development of novel diagnostic and prognostic molecular markers for sporadic colon cancer

Gene expression studies are informative about changes in colon cancer, increase understanding of the biology of tumorigenesis and aid in developing diagnostic and prognostic markers. In this review, expression techniques used to examine the multistage process of colon cancer are discussed. Many genes have been found to differ in expression between normal and tumorigenic states, as early as the seemingly normal colonic crypts. The clinical usefulness of markers varies with stage, ethnicity and anatomic location of colon cancer. Thus, combinations of markers can be used to develop an approach to molecularly screen and follow the progression of this prevalent cancer.

Lack of association between expression of MRP2 and early relapse of colorectal cancer in patients receiving FOLFOX-4 chemotherapy

Recurrence following failure of chemotherapy limits the application of high doses of anticancer drugs currently used for eliminating cancerous cells. It has been identified that ATP-binding cassette (ABC) multidrug transporters are associated with chemoresistance, which is a major obstacle in cancer therapy. The present study aimed to investigate the association of pretherapeutic multidrug resistance-associated protein 2 (MRP2) expression with response to chemotherapy in stage II/III colorectal cancer (CRC). Protein expression was determined by immunohistochemical analysis of 50 archival samples from patients who had not received preoperative chemotherapy and radiotherapy. All patients were treated with 5-fluorouracil/leucovorin (FL) plus oxaliplatin (FOLFOX-4) regimen for 6 months following curative resection. During the 12 months of follow-up, local and distant recurrences were observed in 15 (30%) cases, of which 5 occurred at the time of chemotherapy. MRP2 expression was observed in 24 (48%) and 7 (14%) cases in the tumor tissues and matched normal tissues, respectively. A significant difference was observed between the positive expression frequency in the tumor tissues compared to the surrounding normal mucosa (P=0.003). The incidence of recurrence and metastasis for patients in the MRP2-positive group was lower than that in the MRP2-negative group (P>0.05); however, all 5 cases who demonstrated recurrence during their treatment were MRP2-positive (P=0.022). MRP2 expression was not correlated with the clinicopathological markers in this group of patients. Kaplan-Meier analysis revealed that MRP2 expression was not associated with a shorter disease-free survival or overall survival of patients (P>0.05). The results of this study indicated that MRP2 is overexpressed in the course of CRC development and progression. However, expression of MRP2 was not associated with recurrence of patients treated with FL and oxaliplatin in the population studied.

The potential for serum p53 to predict the response to chemotherapy of patients with gastric cancer

This study was designed to investigate the relationship between serum p53, tissue p53 and tissue permeability glycoprotein (P-gp) levels in gastric cancer. Serum levels of p53 were detected by enzyme-linked immunosorbent assay, and tissue p53 and P-gp levels were analysed by immunohistochemistry. In total, 63.0% of gastric cancer tissue samples tested positive for P-gp and 58.7% of samples tested positive for p53. Tissue P-gp immunoreactivity was significantly correlated with tissue p53 immunoreactivity, and both tissue p53 and P-gp immunoreactivity were significantly correlated to the degree of cancer cell differentiation. The percentage of gastric cancer patients with serum positive for p53 was 36.2%, which was significantly higher than the rate in non-cancerous gastric disease patients. Serum p53 was significantly correlated to tissue p53 and tissue P-gp, inferring that the presence of p53 in the serum could indicate the status of tissue p53 and P-gp. This could, therefore, be useful for screening for the most appropriate (lowest toxicity and highest effectiveness) drugs to use ahead of (neo)-adjuvant chemotherapy.

Early response evaluation and prediction in neoadjuvant-treated patients with esophageal cancer

Since the introduction of multimodal therapy regimens, the prognosis of esophageal cancer has improved. There is undoubtedly true for patients with surgically resected tumors in the case of a response to neoadjuvant chemotherapy or chemoradiation. Important conclusions can be drawn from this regarding the indication for perioperative therapies, the radicality of surgery, or the surgical indications. Thus, most of the current research in this field is aimed at the early identification of this subset of patients, at the beginning of, or even before, neoadjuvant treatment. Conventional staging tools have failed to predict responses to neoadjuvant therapy. However, molecular imaging methods, e.g. positron emission tomography (PET)-scans, have shown promising results in the early selection of responders and non-responders during the course of neoadjuvant therapy, allowing physicians to alter the treatment plan accordingly. Even more desirable is the identification of potential responders before the start of neoadjuvant therapy. Preliminary molecular data on biopsy specimens demonstrate the possibility of early response prediction in these patients. We present the current knowledge on response evaluation and prediction in esophageal cancer and draw conclusions for future clinical practice and studies in this review.

Association between p53 expression and Bcl-2, P-glycoprotein, topoisomerase II alpha, thymidylate synthase and thymidine phosphorylase as potential therapeutic targets in colorectal cancer patients

We evaluated the expression of molecular markers in colorectal adenocarcinoma in relation to p53 protein expression. Tissue samples of 54 patients with colorectal adenocarcinoma were obtained at surgery at university hospitals in the years 2000-2003. These were analyzed by immunohistochemical techniques using primary antibodies for p53, Bcl-2, P-gp, topoisomerase II alpha and Thymidylate Synthase (TS), thymidine phosphorylase/PD- ECGF (TP) and LSAB detection kit. The highest prevalence of expression among six analyzed markers were P-gp and p53 with 77% expression and the lowest one was Topo II with 35% expression. No clinicopathological significance was recorded in colorectal cancer patients. Several immunophenotypes were observed between p53 and other molecular markers. Additionally the prevalence of lack of expression of Bcl-2, Topo II and TS was higher in p53+ tumors than in p53-tumors. A significant association (p = 0.021) existed between p53/Bcl-2 coexpression and mean age of patients (63.5 [10.1]y vs. 52.3 [15.2] y) and between p53/TP coexpression and sex (66.7% male; (p = 0.022). Overexpression of mutated p53 seen in tumor samples may alter the expression pattern of other molecular markers that are predictors of tumor response to chemotherapy regimens. Age and sex of patients could also affect the p53 related proteins such as Bcl-2 and TP, which can affect therapeutic outcome and disease prognosis. These findings emphasize the importance of tumor immunophenotypes as valuable prognostic or predictive markers in clinical settings.

Predicting the response of localised oesophageal cancer to neo-adjuvant chemoradiation

BACKGROUND

A complete pathological response to neo-adjuvant chemo-radiation for oesophageal cancer is associated with favourable survival. However, such a benefit is seen in the minority. If one could identify, at diagnosis, those patients who were unlikely to respond unnecessary toxicity could be avoided and alternative treatment can be considered. The aim of this review was to highlight predictive markers currently assessed and evaluate their clinical utility.

METHODS

A systematic search of Pubmed and Google Scholar was performed using the following keywords; "neo-adjuvant", "oesophageal", "trimodality", "chemotherapy", "radiotherapy", "chemoradiation" and "predict". The original manuscripts were sourced for further articles of relevance.

RESULTS

Conventional indices including tumour stage and grade seem unable to predict histological response. Immuno-histochemical markers have been extensively studied, but none has made its way into routine clinical practice. Global gene expression from fresh pre-treatment tissue using cDNA microarray has only recently been assessed, but shows considerable promise. Molecular imaging using FDG-PET seems to be able to predict response after neo-adjuvant chemoradiation has finished, but there is a paucity of data when such imaging is performed earlier.

CONCLUSION

Currently there are no clinically useful predictors of response based on standard pathological assessment and immunohistochemistry. Genomics, proteomics and molecular imaging may hold promise.

Molecular markers that predict response to colon cancer therapy

Progress in the treatment of colon cancer depends on the development of target-based molecules built on an improved understanding of the molecular biology of the disease. Defining end points for chemotherapy resistance is needed as drug resistance develops quickly and patients demonstrate variation in response to chemotherapy. Many techniques that measure a marker's preponderance have been developed including biochemical, immunohistochemical, genomics, proteomics or a combination thereof. However, standardization of these techniques that measure either genes or their protein products is urgently needed. This article reviews several markers (TS,TP, DPD, FT, EGFR, VEGF, CD44v6, TRAIL, microsatellite instability, allelic deletions, oncogenes and suppressor genes [c-myc, Ki-Ras, p53, p21, Topo I, Topo IIalpha, Fos, hMLH1, Bcl-2/Bax and MDR1], MDR-related proteins [Pgp, MRP and LRP], genomic polymorphisms [XPD, ERCC1, GSTP1 and TS 3 -UTR] and COX-;2) that influence DNA metabolism, DNA damage, programmed cell death, the immune or vascular system, or lead to mutations. When combined together and tested by newly developed genomic and proteomic approaches, many of these markers provide a more sensitive indicative predictor of response than when evaluated separately or by older biochemical, immunohistologic or morphologic methods. A global approach involving the simultaneous testing of several predictive multimarkers will provide critical information for improving chemotherapy to alleviate suffering from this disease.

Serine protease HtrA1 modulates chemotherapy-induced cytotoxicity

Resistance to chemotherapy presents a serious challenge in the successful treatment of various cancers and is mainly responsible for mortality associated with disseminated cancers. Here we show that expression of HtrA1, which is frequently downregulated in ovarian cancer, influences tumor response to chemotherapy by modulating chemotherapy-induced cytotoxicity. Downregulation of HtrA1 attenuated cisplatin- and paclitaxel-induced cytotoxicity, while forced expression of HtrA1 enhanced cisplatin- and paclitaxel-induced cytotoxicity. HtrA1 expression was upregulated by both cisplatin and paclitaxel treatment. This upregulation resulted in limited autoproteolysis and activation of HtrA1. Active HtrA1 induces cell death in a serine protease-dependent manner. The potential role of HtrA1 as a predictive factor of clinical response to chemotherapy was assessed in both ovarian and gastric cancer patients receiving cisplatin-based regimens. Patients with ovarian or gastric tumors expressing higher levels of HtrA1 showed a higher response rate compared with those with lower levels of HtrA1 expression. These findings uncover what we believe to be a novel pathway by which serine protease HtrA1 mediates paclitaxel- and cisplatin-induced cytotoxicity and suggest that loss of HtrA1 in ovarian and gastric cancers may contribute to in vivo chemoresistance.

Treatment for multiple bilobar liver metastases of colorectal cancer

BACKGROUND

Recent advances have extended indications for hepatectomy to include multiple bilobar colorectal liver metastases (CLM). Staging systems based on the biological malignancy of primary and metastatic tumors provide appropriate indications for hepatectomy in CLM. However, suitability for resection in patients with complex and extensive hepatic metastases is controversial.

METHODS

A medline search was performed to identify papers reporting the resection for CLM. Techniques, indication, and results were reviewed.

RESULTS

If the anticipated remnant liver volume is small (25-40% of total), suggesting a high risk of postoperative liver failure, portal vein embolization (PVE) is recommended prior to hepatectomy. However, curative resections are not always possible. Specifically in synchronous multiple bilobar CLM, two-stage hepatectomy, comprising bilateral hepatectomy and primary resection with or without PVE, can prevent growth of ipsilateral metastatic nodules in the remnant liver and reduce surgical risk. Several local ablation techniques can complement surgery if hepatic resection alone increases the risk of postoperative liver failure or is not curative. Chemotherapy combined with targeted treatment can suppress recurrence and extend indications for hepatectomy by reducing the size and number of primary irresectable tumors.

CONCLUSION

PVE or staged procedure combining with local ablation or neoadjuvant, downstaging or adjuvant therapies extends indications for hepatectomy to include multiple bilobar CLM. The 5-year survival rate for multiple bilobar CLM treated with alternating hepatectomy and chemotherapy is comparable to the values reported for single and hemilateral CLM.

Gastric cancer

Gastric cancer is one of the most common cancers and one of the most frequent causes of cancer-related deaths. The incidence, diagnostic studies, and therapeutic options have undergone important changes in the last decades, but the prognosis for gastric cancer patients remains poor, especially in more advanced stages. Surgery is the mainstay of treatment of this disease, even if it is associated with a high rate of locoregional and distant recurrence. There is ongoing debate regarding the role of adjuvant treatment In advanced disease, palliation of symptoms, rather than cure, is the primary goal of patient management. Several combination therapies have been developed and have been examined in phase III trials; however, in most cases, they have failed to demonstrate a survival advantage over the reference arm. This review summarizes the most important recommendations for the management of patients with gastric cancer.

Deleted in Colon Cancer Protein Expression in Colorectal Cancer Metastases: A Major Predictor of Survival in Patients With Unresectable Metastatic Disease Receiving Palliative Fluorouracil-Based Chemotherapy

Purpose

To determine whether deleted in colon cancer (DCC) protein expression in colorectal cancer (CRC) metastases could predict outcome to palliative fluorouracil (FU)-based chemotherapy and to assess whether it is similar to that observed in the corresponding primary tumors.

Patients and Methods

DCC protein expression was assessed immunohistochemically on archival specimens of CRC metastases from 42 patients homogeneously treated by methotrexate-modulated bolus FU alternated to 6-S-leucovorin–modulated infused FU and was retrospectively correlated with patient characteristics and clinical outcome. In a subset analysis, DCC immunoreactivity was compared between metastatic CRC and the corresponding primary tumors and regional lymph node metastases.

Results

Positive immunoreactivity for DCC was found in 45% of patients. Eighteen (78%) of 23 patients for whom multiple samples were available displayed a similar pattern of expression in distant metastases and primary tumors. The median survival time was 14.3 months in patients without DCC expression and 21.4 months in patients with DCC-positive tumors (log-rank test, P = .04); the 2-year survival rates were 8.5% and 42.5%, respectively. Response rates to chemotherapy were not significantly different between the two groups. By multivariate analysis, DCC protein expression maintained its prognostic value and showed to be the single best predictor of survival, with a relative risk of 2.16.

Conclusion

Our results indicate that expression of the DCC protein in CRC metastases is similar to that observed in the corresponding primary tumors and represents a dominant predictor of survival in patients with unresectable, advanced CRC who are undergoing palliative FU-based chemotherapy.

Clinical utility of biochemical markers in colorectal cancer: European Group on Tumour Markers (EGTM) guidelines

In recent years, numerous serum and cell/tissue-based markers have been described for colorectal cancer (CRC). The aim of this article was to provide guidelines for the routine clinical use of some of these markers. Lack of sensitivity and specificity preclude the use of any available serum markers such as carcinoembryonic antigen (CEA), CA 19-9, CA 242, CA 72-4, tissue polypeptide antigen (TPA) or tissue polypeptide-specific antigen (TPS) for the early detection of CRC. However, preoperative measurement of CEA is desirable as this may give independent prognostic information, help with surgical management and provide a baseline level for subsequent determinations. For patients with stage 2 (Dukes' B) and 3 (Dukes' C) disease who may be candidates for liver resection, CEA levels should be measured every 2-3 months for at least 3 years after diagnosis. For monitoring treatment of advanced disease, CEA should also be tested every 2-3 months. Insufficient evidence is presently available to recommend the routine use of other serum markers for monitoring purposes. Similarly, the new cell and tissue-based markers (e.g, ras, P53) cannot yet be recommended for routine clinical use.