p53 and p27 as predictors of clinical outcome for rectal-cancer patients receiving neoadjuvant therapy

p21 as a Predictor and Prognostic Indicator of Clinical Outcome in Rectal Cancer Patients

The cell cycle plays a key and complex role in the development of human cancers. p21 is a potent cyclin-dependent kinase inhibitor (CDKI) involved in the promotion of cell cycle arrest and the regulation of cellular senescence. Altered p21 expression in rectal cancer cells may affect tumor cells' behavior and resistance to neoadjuvant and adjuvant therapy. Our study aimed to ascertain the relationship between the differential expression of p21 in rectal cancer and patient survival outcomes. Using tissue microarrays, 266 rectal cancer specimens were immunohistochemically stained for p21. The expression patterns were scored separately in cancer cells retrieved from the center and the periphery of the tumor; compared with clinicopathological data, tumor regression grade (TRG), disease-free, and overall survival. Negative p21 expression in tumor periphery cells was significantly associated with longer overall survival upon the univariate (p = 0.001) and multivariable analysis (p = 0.003, HR = 2.068). Negative p21 expression in tumor periphery cells was also associated with longer disease-free survival in the multivariable analysis (p = 0.040, HR = 1.769). Longer overall survival times also correlated with lower tumor grades (p= 0.011), the absence of vascular and perineural invasion (p = 0.001; p < 0.005), the absence of metastases (p < 0.005), and adjuvant treatment (p = 0.009). p21 expression is a potential predictive and prognostic biomarker for clinical outcomes in rectal cancer patients. Negative p21 expression in tumor periphery cells demonstrated significant association with longer overall survival and disease-free survival. Larger prospective studies are warranted to investigate the ability of p21 to identify rectal cancer patients who will benefit from neoadjuvant and adjuvant therapy.

Kif4A mediates resistance to neoadjuvant chemoradiotherapy in patients with advanced colorectal cancer via regulating DNA damage response

More and more patients with advanced colorectal cancer (CRC) have benefited from surgical resection or ablation following neoadjuvant chemoradiotherapy (nCRT), but nCRT may be ineffective and have potential risks to some patients. Therefore, it is necessary to discover effective biomarkers for predicting the nCRT efficacy in CRC patients. Chromokinesin Kif4A plays a critical role in mitosis, DNA damage repair and tumorigenesis, but its relationship with nCRT efficacy in advanced CRC remains unclear. Here, we find that Kif4A expression in pretreated tumor tissue is positively correlated with poorer tumor regression after receiving nCRT ( P=0.005). Knockdown of endogenous Kif4A causes an increased sensitivity of CRC cells to chemotherapeutic drugs 5-fluorouracil (5-FU) and Cisplatin (DDP), while overexpression of Kif4A enhances resistance of CRC cells to the chemotherapeutic drugs. Furthermore, depending on its motor domain and tail domain, Kif4A regulates DNA damage response (DDR) induced by 5-FU or DDP treatment in CRC cells. In conclusion, we demonstrate that Kif4A may be a potential independent biomarker for predicting the nCRT efficacy in advanced CRC patients, and Kif4A regulates chemosensitivity of CRC cells through controlling DDR.

Personalized Medicine-Current and Emerging Predictive and Prognostic Biomarkers in Colorectal Cancer

Colorectal cancer (CRC) is the third most common cancer diagnosed worldwide and is heterogeneous both morphologically and molecularly. In an era of personalized medicine, the greatest challenge is to predict individual response to therapy and distinguish patients likely to be cured with surgical resection of tumors and systemic therapy from those resistant or non-responsive to treatment. Patients would avoid futile treatments, including clinical trial regimes and ultimately this would prevent under- and over-treatment and reduce unnecessary adverse side effects. In this review, the potential of specific biomarkers will be explored to address two key questions—1) Can the prognosis of patients that will fare well or poorly be determined beyond currently recognized prognostic indicators? and 2) Can an individual patient’s response to therapy be predicted and those who will most likely benefit from treatment/s be identified? Identifying and validating key prognostic and predictive biomarkers and an understanding of the underlying mechanisms of drug resistance and toxicity in CRC are important steps in order to personalize treatment. This review addresses recent data on biological prognostic and predictive biomarkers in CRC. In addition, patient cohorts most likely to benefit from currently available systemic treatments and/or targeted therapies are discussed in this review.

Nomogram for prediction of pathologic complete remission using biomarker expression and endoscopic finding after preoperative chemoradiotherapy in rectal cancer

Objective

The aim of this study is to develop a nomogram for prediction of pathologic complete remission (pCR) after preoperative chemoradiotherapy (CRT) for rectal cancer.

Methods

mRNA expression levels of seven molecular markers [p53, p21, Ki-67, vascular endothelial growth factor (VEGF), CD133, CD24, CD44] were measured by reverse transcriptase polymerase chain reaction (RT-PCR) in 120 rectal cancers. Endoscopic findings of clinical complete remission (cCR) and biologic variables were used to construct nomogram in the training group (n=80), which was validated in the validation group (n=40).

Results

mRNA expression levels of four markers (p53, p21, Ki67, CD133) correlated with pCR (24/80, 30.0%) in the training group. Low expression of p53 and/or high expression of p21, Ki67 and CD133 showed greater pCR rate. pCR was shown in 18 (69.2%) of 26 cases showing endoscopic cCR in the training group. Higher pCR rate was demonstrated in lower tumor location than middle tumor (19/49, 38.8% vs. 5/31, 16.1%). A nomogram for prediction of pCR was developed from the multivariate prediction model using these six variables, which showed good discrimination ability in the training group [area under the curve (AUC)=0.945] and validation group (AUC=0.922). The calibration plot showed good agreement between actual and predicted pCR in both patient groups.

Conclusions

Nomogram for assessment of pCR can be useful for making treatment decisions after CRT according to predicted responses.

Are there predictors that can determine neoadjuvant treatment responses in rectal cancer?

BACKGROUND/AIMS

This study aimed to determine a predictive bioindicator that would detect the treatment response of patients diagnosed with rectal cancer and treated with neoadjuvant chemoradiotherapy (nCRT).

MATERIALS AND METHODS

The data collected from 37 patients receiving nCRT were retrospectively evaluated. The p53 score and gene instability in MLH1 and MSH2, which are among the DNA mismatch repair (MMR) genes, were evaluated using immunohistochemical methods. The neutrophils-leukocytes ratio (NLR), carcinoembryonic antigen (CEA), and carbohydrate antigen (CA) 19-9 values were obtained as hematological parameters from computer records. The pathologic analysis of the therapy response after nCRT was classified according to the modified grading system by Ryan et al. Results: The changes in the NLR, CEA, and CA19-9 values before and after treatment were statistically significant (p<0.001 and p=0.005). A near significant effect of the decrease of the CEA value in the 5th week after treatment was detected on the pathological response score (p=0.075). The p53 mutation score in those patients with any residue was higher than the total response. Overall, 89.2% of the patients exhibited MMR positivity (stability), and 10.8% of the cases with MRM negativity (instability) had a macroscopic residue. Cases with pathological total response were MRM positive.

CONCLUSION

Consequently, in most of the patients treated with nCRT, the treatment caused tumor and nodal remission. In the prediction of this therapy response, hematological and genetic parameters, such as NLR, P53, MLH1, and MSH2, play a predictive role.

Lysosomes contribute to radioresistance in cancer

Radiotherapy is one of the most widely used methods to treat human tumors. Efficacy is due mainly to the DNA damage it induces. However, tumor cells often develop responsive adaptiveness to radiation treatment to survive, which leads to radioresistance. Many cellular processes, such as DNA damage repair, cell cycle arrest and autophagy, are involved in the development of radioresistance. Few interventions to combat radioresistance exist to date. In recent years, the lysosome has been reported to contribute to chemo- and radioresistance. Although for many years, the lysosome was known as an organelle that degrades waste materials, we now know it is also involved in important signaling pathways regulating cellular homeostasis. Although an increasing number of preclinical studies show that lysosome-related factors promote radioresistance, the role of the lysosome in radioresistance has not been systematically demonstrated. Here, we combine an updated understanding of lysosomes with a review of current studies regarding the role of lysosomes in mediating radioresistance.

Nucleotide Excision Repair Factor XPC Ameliorates Prognosis by Increasing the Susceptibility of Human Colorectal Cancer to Chemotherapy and Ionizing Radiation

Nucleotide excision repair (NER) is a DNA damage repair mechanism in mammals, but the relationship between NER and human colorectal cancer (HRC) progression has not been clarified yet. In this study, the expression of the NER genes XPA, XPC, XPF, XPG, ERCC1, and XPD was measured in normal and cancerous human colorectal tissue. Among them, only the XPC gene expression was significantly increased in colorectal cancer tissue. To establish the role of XPC in colorectal cancer, small interference RNA (siRNA) targeting XPC was used to knockdown the expression of XPC in HRC cell lines. In addition, an expression vector plasmid containing the XPC cDNA was constructed and stably transfected into HRC cell lines to overexpress the XPC gene. Interestingly, MTT and apoptosis assay demonstrated that XPC gene overexpression significantly increased the susceptibility of HRC cell lines to cisplatin and X-ray radiation. In order to study the relationship between XPC expression and the progression of HRC, XPC expression was measured in 167 patients with colorectal cancer. The results showed that patients with high XPC expression had longer survival time. Cox regression analysis showed that high XPC expression might be a potential predictive factor for colorectal cancer. In conclusion, XPC plays a key role in the susceptibility of colorectal cancer to chemotherapy and ionizing radiation and is associated with a good patients' prognosis.

Molecular Biology: Are We Getting Any Closer to Providing Clinically Useful Information?

Advances in molecular biology and biomarker research have significantly impacted our understanding and treatment of multiple solid malignancies. In rectal cancer, where neoadjuvant chemoradiation is widely used for locally advanced disease, most efforts have focused on the identification of predictors of response in an attempt to appropriately select patients for multimodality therapy. A variety of biomarkers have been studied, including genetic mutations, chromosomal copy number alterations, and single as well as multigene expression patterns. Also, as transanal resection of rectal tumors requires accurate preoperative detection of lymph node metastasis, the identification of biomarkers of regional nodal involvement has been another important field of active research. While preliminary results have been promising, lack of external validation means has a limited translation to clinical use. This review summarizes recent developments in rectal cancer biomarker research, highlighting the challenges associated with their adoption, and evaluating their potential for clinical use.

Predictive clinical model of tumor response after chemoradiation in rectal cancer

Survival improvement in rectal cancer treated with neoadjuvant chemoradiotherapy (nCRT) is achieved only if pathological response occurs. Mandard tumor regression grade (TRG) proved to be a valid system to measure nCRT response. The ability to predict tumor response before treatment may significantly have impact the selection of patients for nCRT in rectal cancer. The aim is to identify potential predictive pretreatment factors for Mandard response and build a clinical predictive model design. 167 patients with locally advanced rectal cancer were treated with nCRT and curative surgery. Blood cell counts in peripheral blood were analyzed. Pretreatment biopsies expression of cyclin D1, epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF) and protein 21 were assessed. A total of 61 single nucleotide polymorphisms were characterized using the Sequenom platform through multiplex amplification followed by mass-spectometric product separation. Surgical specimens were classified according to Mandard TRG. The patients were divided as: "good responders" (Mandard TRG1-2) and "poor responders" (Mandard TGR3-5). We examined predictive factors for Mandard response and performed statistical analysis. In univariate analysis, distance from anal verge, neutrophil lymphocyte ratio (NLR), cyclin D1, VEGF, EGFR, protein 21 and rs1810871 interleukin 10 (IL10) gene polymorphism are the pretreatment variables with predictive value for Mandard response. In multivariable analysis, NLR, cyclin D1, protein 21 and rs1800871 in IL10 gene maintain predictive value, allowing a clinical model design.

CONCLUSION

It seems possible to use pretreatment expression of blood and tissue biomarkers, and build a model of tumor response prediction to neoadjuvant chemoradiation in rectal cancer.

Identification of molecular characteristics induced by radiotherapy in rectal cancer based on microarray data

The present study aimed to reveal the molecular characteristics induced by radiotherapy in rectal cancer at the transcriptome level. Microarray data (ID, GSE26027) downloaded from the Gene Expression Omnibus database were re-analyzed to identify differentially expressed genes (DEGs) between rectal cancer tissues during and prior to radiotherapy. The DEGs were then inputted into the database for annotation, visualization and integrated discovery, an online tool to perform enrichment analyses, and into the search tool for the retrieval of interacting genes/proteins database to identify protein-protein interactions (PPIs). Subsequently, a PPI network was constructed, which was screened for densely connected modules. Furthermore, protein domain enrichment analysis was performed. In total, 690 DEGs, including 179 upregulated and 511 downregulated DEGs, were found in rectal cancer tissues during and prior to radiotherapy. The upregulated DEGs were significantly enriched in 'positive regulation of transport' and 'regulation of cardiac muscle contraction', while the downregulated DEGs were most markedly enriched in 'cell migration', 'cell-cell signaling', 'extracellular matrix organization' and 'blood vessel development', including prostaglandin-endoperoxide synthase 2, transforming growth factor β-induced, 68 kDa endothelin receptor type A, brain-derived neurotrophic factor, TIMP metallopeptidase inhibitor 1, and serpin family E member 1, which were the top 6 hub nodes in the PPI network. Furthermore, 2 protein domains were significantly enriched by PPI modules, including: The collagen triple helix repeat (CTHR) family members collagen type (COL) 5A2, COL9A3, COL6A3, COL21A1, COL5A3, COL11A1, COL7A1 and CTHR-containing-1; and the olfactory receptor family (OR) members OR7E24, OR7A17, OR6A2, OR1F1, OR10H3 and OR7A10. A total of 7 upregulated DEGs were characterized as tumor suppressor genes, and 8 downregulated DEGs were characterized as oncogenes. The biological processes or protein domains enriched by upregulated or downregulated DEGs may improve the understanding of molecular characteristics in response to radiotherapy.

Biomarker-Based Scoring System for Prediction of Tumor Response After Preoperative Chemoradiotherapy in Rectal Cancer by Reverse Transcriptase Polymerase Chain Reaction Analysis

BACKGROUND

Numerous molecular markers have been investigated to predict tumor response after preoperative chemoradiotherapy for rectal cancer.

OBJECTIVE

This study aimed to evaluate the predictive value of biomarkers for the prediction of tumor response after preoperative chemoradiotherapy.

DESIGN & SETTING

Tumor specimens have been collected prospectively from 80 patients with rectal cancer who underwent curative resection at 8 weeks after completing preoperative chemoradiotherapy.

MAIN OUTCOME MEASURES

With the use of reverse transcriptase polymerase chain reaction analysis, mRNA expression levels of 7 candidate biomarkers (p53, p21, Ki-67, VEGF, CD133, CD24, and CD44) were evaluated from fresh tumor samples collected before preoperative chemoradiotherapy. The correlation between biomarker expression levels and the pathologic response was assessed based on histopathological staging (pTNM) and tumor regression grade.

RESULTS

The mRNA expression levels of 4 biomarkers (p53, p21, Ki67, and CD133) significantly correlated with tumor regression grade response and pathologic complete response. Patients showing low expression of p53 and/or high expression of p21, Ki67, and CD133 exhibited a significantly greater tumor regression grade response and pathologic complete response rate. A scoring system devised so that 1 point was given for each biomarker whose expression level correlated with pathologic complete response (score range: 0-4) showed that 9 of 62 patients with scores of 0 to 2 achieved pathologic complete response, whereas 15 of 18 patients with scores of 3 to 4 achieved pathologic complete response (14.5% vs 83.3%, p < 0.001). For prediction of pathologic complete response, the scoring system showed 62.5% sensitivity, 94.6% specificity, an 83.3% positive predictive value, and an 85.5% negative predictive value.

LIMITATIONS

Small patient numbers have limitations related to the reproducibility and ability to provide quantitative information. In addition, this study lacks test and validation sets.

CONCLUSIONS

The pretreatment mRNA expression levels of 4 biomarkers correlated with pathologic tumor response after intraoperative chemoradiotherapy in rectal cancer. Furthermore, the scoring system combining values of biomarker expression might have predictive power with high positive and negative predictive values.

A prospective feasibility study to evaluate neoadjuvant-synchronous S-1 with radiotherapy for locally advanced rectal cancer: A multicentre phase II trial

Treatment results of locally advanced rectal cancer without preoperative chemoradiotherapy (CRT) in Japan do not differ from those of Western countries. Preoperative CRT with new anticancer agents may decrease local recurrence rate and prevent distant metastases, thus improving survival. We conducted a trial to evaluate feasibility of neoadjuvant CRT using S-1 in patients with locally advanced rectal cancer. A multi-institutional (17 specialized centres), interventional, phase II trial was conducted from April 2009 to August 2011. Patients fulfilling the following requirements before neoadjuvant CRT were included: histologically proven rectal carcinoma; tumour in the upper or lower rectum; cancer classified as T3-4 N0-3 M0. Neoadjuvant CRT with S-1 (80 mg/m²/day on days 1-5, 8-12, 22-26, and 29-33) and irradiation (total 45 Gy/25 fr, 1.8 Gy/day, on days 1-5, 8-12, 15-19, 22-26, and 29-33) was performed. Total mesorectal excision with D3 lymphadenectomy was performed during weeks 4 and 8 after completion of neoadjuvant CRT. The primary endpoint was completion rate of neoadjuvant CRT. Secondary endpoints were response rate to neoadjuvant CRT, short-term clinical outcomes, curative resection rate, and pathologic response (grade 2/3). Of the 37 patients included, 86.5% completed neoadjuvant CRT (95% CI, 75.5-97.5%), and 10.8% (4) experienced an adverse event (grade 3/4). Response rate (RECIST 1.0) was 56.8% (95% CI, 40.8-72.7%), and pathologic response rate was 48.6% (95% CI, 32.5-64.8%). This study demonstrated that neoadjuvant-synchronous S-1+radiotherapy for locally advanced rectal cancer was feasible in terms of pathologic response and adverse events. Registration number: UMIN-CTR, No. C003396.

New Perspectives on Predictive Biomarkers of Tumor Response and Their Clinical Application in Preoperative Chemoradiation Therapy for Rectal Cancer

Preoperative chemoradiation therapy (CRT) is the standard treatment for patients with locally advanced rectal cancer (LARC) and can improve local control and survival outcomes. However, the responses of individual tumors to CRT are not uniform and vary widely, from complete response to disease progression. Patients with resistant tumors can be exposed to irradiation and chemotherapy that are both expensive and at times toxic without benefit. In contrast, about 60% of tumors show tumor regression and T and N down-staging. Furthermore, a pathologic complete response (pCR), which is characterized by sterilization of all tumor cells, leads to an excellent prognosis and is observed in approximately 10-30% of cases. This variety in tumor response has lead to an increased need to develop a model predictive of responses to CRT in order to identify patients who will benefit from this multimodal treatment. Endoscopy, magnetic resonance imaging, positron emission tomography, serum carcinoembryonic antigen, and molecular biomarkers analyzed using immunohistochemistry and gene expression profiling are the most commonly used predictive models in preoperative CRT. Such modalities guide clinicians in choosing the best possible treatment options and the extent of surgery for each individual patient. However, there are still controversies regarding study outcomes, and a nomogram of combined models of future trends is needed to better predict patient response. The aim of this article was to review currently available tools for predicting tumor response after preoperative CRT in rectal cancer and to explore their applicability in clinical practice for tailored treatment.

The impact of pathologic nodal status on survival following neoadjuvant chemoradiation for locally advanced rectal cancer

PURPOSE

For patients with locally advanced rectal cancer, the accuracy rates of preneoadjuvant therapy nodal staging and potential nodal downstaging make the prognostic significance of nodal status unclear. We therefore sought to review our experience in order to better understand the impact of clinical and pathologic nodal status upon patient outcomes.

METHODS

174 patients were identified as having undergone neoadjuvant chemoradiation and resection for rectal cancer. For analytic purposes, patients were grouped into four nodal categories (uN( 0)· pN( 0), uN( 0)· pN( +), uN (+) · pN( 0), and uN (+) · pN( +)). Univariate and multivariate analyses were performed.

RESULTS

104 men and 70 women of median age 60 years (29-85 years) were followed for a median of 31 months (1-121 months). Nodal staging was available for 129 patients, with a median of 8 lymph nodes (range 0-39) evaluated. Disease recurred in 3 of 41 (7%) uN   (0) ·pN (  0), 10 of 52 (20%) uN (   +)·pN (  0), 7 of 18 (41%) uN (  0)·pN (   +), and 6 of 17 (35%) uN (  +)·pN (  +) patients. Those patients having nodal downstaging (uN (  +)·pN (  0)) experienced superior overall survival (p = 0.03). Only pathologic nodal status was a significant predictor of both disease-free and overall survival in multivariate modeling. Adjuvant chemotherapy did not impact disease-free or overall survival for patients with pN0.

CONCLUSIONS

Pathologic nodal status may represent a superior predictor of survival for patients with local advanced rectal cancers. Our findings may have potential implications for the application of adjuvant therapy.

Genotypic characteristics of resistant tumors to pre-operative ionizing radiation in rectal cancer

Due to a wide range of clinical response in patients undergoing neo-adjuvant chemoradiation for rectal cancer it is essential to understand molecular factors that lead to the broad response observed in patients receiving the same form of treatment. Despite extensive research in this field, the exact mechanisms still remain elusive. Data raging from DNA-repair to specific molecules leading to cell survival as well as resistance to apoptosis have been investigated. Individually, or in combination, there is no single pathway that has become clinically applicable to date. In the following review, we describe the current status of various pathways that might lead to resistance to the therapeutic applications of ionizing radiation in rectal cancer.

p27 expression in post-treatment rectal cancer: a potential novel approach for predicting residual nodal disease

BACKGROUND

Expression profiles of p21, p27, p53, Ki-67, and thymidylate synthase may be associated with response to neoadjuvant chemoradiation. The relationship between post-treatment protein expression and regional lymph node involvement has not been fully explored.

METHODS

Tumor cores from 126 rectal cancer patients underwent immunohistochemical analysis for the aforementioned proteins. Staining indices (SIs) using percentage of stained cells and staining intensity were calculated for 10 tumor cores per patient. SI for each marker was compared between node negative and node positive patients.

RESULTS

Twenty-six (20.6%) cancer patients had a pathologic complete response and 37 had inadequate tissue or cancer cells, leaving 63 for analysis. Thirty-seven (58.7%) cancer patients were node negative and 26 (41.3%) were node positive. There was an association between increased p27 SI and nodal positivity (P = .04).

CONCLUSION

Increased p27 expression in post-treatment rectal cancer is associated with nodal positivity and may determine which patients are suitable for local excision.

Molecular markers for targeted neoadjuvant rectal cancer therapy

SUMMARY Neoadjuvant chemoradiotherapy is the standard of care for locally advanced rectal cancer. While neoadjuvant chemoradiation has been demonstrated to improve oncological outcomes, there is a wide spectrum of responses to therapy. The ability to predict who will respond favorably or unfavorably to neoadjuvant therapy could prevent unnecessary morbidity and potentially lead to novel therapeutic targets. A number of individual biomarkers and multigene signatures have been investigated as potential means of predicting response to neoadjuvant chemoradiation. While promising, none of these predictive biomarkers have yet been introduced clinically. This review summarizes both individual and multigene biomarkers for rectal cancer response to neoadjuvant chemoradiation.

The prognostic value of the apoptosis pathway in colorectal cancer: a review of the literature on biomarkers identified by immunohistochemistry

Research towards biomarkers that predict patient outcome in colorectal cancer (CRC) is rapidly expanding. However, none of these biomarkers have been recommended by the American Association of Clinical Oncology or the European Group on Tumor Markers. Current staging criteria result in substantial under-and over-treatment of CRC patients. Evasion of apoptosis, a characteristic feature of tumorigenesis, is known to correlate with patient outcome. We reviewed the literature on immunohistochemistry-based studies between 1998 and 2011 describing biomarkers in this pathway in CRC and identified 26 markers. Most frequently described were p53, Bcl-2, survivin, and the Fas and TRAILR1 receptors and their ligands. None of the studies reviewed provided sufficient support for implementing a single marker into current clinical practice. This is likely due to the complex biology of this pathway. We suggest focusing on the combination of key markers within the apoptosis pathway that together represent an ‘apoptotic tumor profile’, which better reflects the status of this pathway in a tumor.

hPEBP4 as a predictive marker for the pathological response of rectal cancer to preoperative radiotherapy

PURPOSE

The ability to predict tumor sensitivity toward radiotherapy is important in the personalized application of preoperative radiotherapy for patients with rectal cancer. The aim of the present study was to test the human phosphatidylethanolamine-binding protein 4 (hPEBP4) as a predictive marker of tumor response to preoperative radiotherapy in patients with rectal cancer.

METHOD

A retrospective analysis was conducted, consisting of 86 patients with locally advanced rectal cancer who underwent short-course preoperative radiotherapy (20 Gy in five fractions for 1 week) followed by a radical resection. Both pretreatment biopsy specimens and resected primary tumor tissue were collected. Immunohistochemistry and tumor regression grading system were used to evaluate the expression of hPEBP4 in the pretreatment biopsy specimens and the response of rectal cancer to radiotherapy, respectively. Expression of hPEBP4 was correlated with tumor regression in the resected specimen and the clinical outcome of the patients as well.

RESULTS

We found that high expression of hPEBP4 was associated with radioresistance in both univariate and multivariate analyses, and patients with a high hPEBP4 expression had a poorer progression-free survival than those with low hPEBP4 expression.

CONCLUSION

Our study revealed the independent predictive values of hPEBP4 in response of rectal cancer to preoperative radiotherapy, which suggests that upregulating hPEBP4 might be a potential mechanism by which rectal cancer cells avoid the destructive effects of radiotherapy.

Immunohistological expression of HIF-1α, GLUT-1, Bcl-2 and Ki-67 in consecutive biopsies during chemoradiotherapy in patients with rectal cancer

The aim of this study was to describe the dynamics of HIF-1α, GLUT-1, Bcl-2 and Ki-67 during chemoradiotherapy (CRT) of rectal cancer, and to investigate the fluctuation of these biomarkers in relation to pathological response to CRT. The study included 86 patients with rectal adenocarcinoma receiving preoperative CRT (>50.4 Gy and Uracil/Tegafur). Immunohistological expressions of HIF-1α, GLUT-1, Bcl-2 and Ki-67 were investigated in biopsies taken before treatment, after 2, 4 and 6 weeks of CRT and in specimens from the operation. Decreasing expressions of HIF-1α, Bcl-2 and Ki-67 were observed during CRT, whereas GLUT-1 overall was unchanged. No significant changes of the markers were observed in the interval between CRT and surgery. A significant association was observed between the presence of residual carcinoma after 6 weeks of treatment and pathological response to CRT, but no association was seen between the fluctuations of any of the markers and response to CRT. This unique material containing specimens before, after and during CRT for rectal cancer demonstrated biological dynamics in HIF-1α, Bcl-2 and Ki-67, but not GLUT-1, expression during CRT, and a significant association was seen between the presence of residual carcinoma after 6 weeks of treatment and pathological response to CRT.

Predicting the response to preoperative radiation or chemoradiation by a microarray analysis of the gene expression profiles in rectal cancer

Preoperative radiotherapy or chemoradiotherapy (CRT) has become a standard treatment for patients with locally advanced rectal cancer. However, there is a wide spectrum of responses to preoperative CRT, ranging from none to complete. There has been intense interest in the identification of molecular biomarkers to predict the response to preoperative CRT, in order to spare potentially non-responsive patients from unnecessary treatment. However, no specific molecular biomarkers have yet been definitively proven to be predictive of the response to CRT. Instead of focusing on specific factors, microarray-based gene expression profiling technology enables the simultaneous analysis of large numbers of genes, and might therefore have immense potential for predicting the response to preoperative CRT. We herein review published studies using a microarray-based analysis to identify gene expression profiles associated with the response of rectal cancer to radiation or CRT. Although some studies have reported gene expression signatures capable of high predictive accuracy, the compositions of these signatures have differed considerably, with little gene overlap. However, considering the promising data regarding gene profiling in breast cancer, the microarray analysis could still have potential to improve the management of locally advanced rectal cancer. Increasing the number of patients analyzed for more accurate prediction and the extensive validation of predictive classifiers in prospective clinical trials are necessary before such profiling can be incorporated into future clinical practice.

Response prediction in the multimodality therapy of locally advanced rectal cancer

SUMMARY Neoadjuvant therapies have been established in the multimodality treatment of locally advanced rectal cancer. Radiation with concurrent 5-fluorouracil-based chemotherapy followed by surgical resection is considered to be the standard of care in advanced rectal cancer. However, recent studies revealed that patients with complete histopathologic response seem to benefit most from neoadjuvant therapies. Consequently, predictive markers to allow individualization of multimodality therapy in locally advanced rectal cancer are mostly required to identify those who will benefit the most. Unfortunately, there is still an immense lack of factors for response assessment in patients with rectal cancer undergoing multimodality treatment. While conventional diagnostic tools lack sufficient accuracy to provide information for response assessment, newer techniques such as [18F]-fluorodeoxyglucose-PET and diffusion-weighted MRI show promising results. In addition, studies on molecular factors for response assessment in rectal cancer are encouraging but still do not provide a reliable instrument for utilization in clinical practice.

Pretreatment CD133 and cyclooxygenase-2 expression as the predictive markers of the pathological effect of chemoradiotherapy in rectal cancer patients

BACKGROUND

CD133 confers chemoradioresistance properties to cells and has recently been used to identify cancer-initiating cells.

OBJECTIVE

We investigated whether the overexpression of CD133 and cyclooxygenase-2 can be used as predictive markers of tumor response to preoperative chemoradiotherapy in patients with rectal cancer.

SETTING

The study was conducted at the National Defense Medical College Hospital in Japan.

PATIENTS

We recruited 96 patients who underwent a single regimen of preoperative short-term chemoradiotherapy (20 Gy in 5 fractions with 400 mg/day Tegafur/Uracil for 1 week) and radical resection.

DESIGN

This was a retrospective study. We obtained pretreatment biopsy specimens of these patients and immunostained these specimens with antibodies for CD133, cyclooxygenase-2, p53, p27, p21, and epidermal growth factor receptor. The resected primary tumor was evaluated according to 2 different tumor regression grading systems that were based on the degrees of fibrosis and cytological alterations.

RESULTS

Positivity for CD133 or cyclooxygenase-2 expression was associated with chemoradioresistance, which was determined by the degree of fibrosis, in both univariate (P = .02 and P = .0003) and multivariate (P = .03 and P = .001) analyses. Univariate and multivariate analyses of the degree of cytological alterations also revealed a significant association between chemoradioresistance and the expression of CD133 (P = .005 and P = .003) and cyclooxygenase-2 (P = .005 and P = .03), whereas other markers failed to associate.

LIMITATIONS

The information on patients' outcome was not available.

CONCLUSIONS

Our study revealed the independent predictive values of CD133 and cyclooxygenase-2 expressions in histological tumor regression after preoperative chemoradiotherapy.

Immunohistochemical analysis of tumour regression grade for rectal cancer after neoadjuvant chemoradiotherapy

AIM

Tumour regression grade (TRG) as defined by Rödel et al. has been used as an independent prognostic factor for rectal carcinoma after preoperative treatment by chemoradiotherapy (CRT). Determination of TRG 2 and 3, semiquantitatively defined as more or less than 50% tumour regression, respectively, does not appear to correlate with prognosis. The purpose of this study was to find an immunohistochemical pattern to permit improved stratification of intermediate responders defined by disease free (DFS) and overall survival (OS).

METHOD

Immunohistochemistry of EGFR (epidermal growth factor receptor), VEGF (vascular endothelial growth factor), CD133 antibody, p53 antibody and Ki67 antibody was evaluated using tissue microarrays (TMA) on post-treatment surgical specimens from 88 patients. CD133 expression was confirmed in the whole section when available.

RESULTS

At a median follow-up of 40 months, TRG was found to be an independent predictor of DFS (P = 0.05) and OS (P = 0.001) but no differences were found between TRG 2 and 3 in terms of DFS (P = 0.74) or OS (P = 0.41). The results of TMA showed an immunohistochemically poor prognostic profile for intermediate responders configured by negativity of CD133 expression. However, when examining CD133 expression in the whole section, there was an intermediate correlation with TMA and the prognostic significance was lost.

CONCLUSION

The results did not confirm the value of immunohistochemistry in predicting the prognosis of patients with rectal cancer following neoadjuvant chemoradiotherapy. This questions the accuracy of TMA in detecting CD133 expression in this setting.

Predictive factors of the response of rectal cancer to neoadjuvant radiochemotherapy

Locally advanced rectal cancer is currently treated with pre-operative radiochemotherapy (pRCT), but the response is not uniform. Identification of patients with higher likelihood of responding to pRCT is clinically relevant, as patients with resistant tumors could be spared exposure to radiation or DNA-damaging drugs that are associated with adverse side effects. To highlight predictive biomarkers of response to pRCT, a systematic search of PubMed was conducted with a combination of the following terms: "rectal", "predictive", "radiochemotherapy", "neoadjuvant", "response" and "biomarkers". Genetic polymorphisms in epithelial growth factor receptor (EGFR) and thymidylate synthase (TS) genes, the expression of several markers, such as EGFR, bcl-2/bax and cyclooxygenase (COX)-2, and circulating biomarkers, such as serum carcinoembryonic antigen (CEA) level, are promising as predictor markers, but need to be further evaluated. The majority of the studies did not support the predictive value of p53, while the values of Ki-67, TS and p21 is still controversial. Gene expression profiles of thousands of genes using microarrays, microRNA studies and the search for new circulating molecules, such as human telomerase reverse transcriptase mRNA and cell-free DNA, are providing interesting results that might lead to the identification of new useful biomarkers. Evaluation of biomarkers in larger, prospective trials are required to guide therapeutic strategies.

Molecular biology: the key to personalised treatment in radiation oncology?

We know considerably more about what makes cells and tissues resistant or sensitive to radiation than we did 20 years ago. Novel techniques in molecular biology have made a major contribution to our understanding at the level of signalling pathways. Before the "New Biology" era, radioresponsiveness was defined in terms of physiological parameters designated as the five Rs. These are: repair, repopulation, reassortment, reoxygenation and radiosensitivity. Of these, only the role of hypoxia proved to be a robust predictive and prognostic marker, but radiotherapy regimens were nonetheless modified in terms of dose per fraction, fraction size and overall time, in ways that persist in clinical practice today. The first molecular techniques were applied to radiobiology about two decades ago and soon revealed the existence of genes/proteins that respond to and influence the cellular outcome of irradiation. The subsequent development of screening techniques using microarray technology has since revealed that a very large number of genes fall into this category. We can now obtain an adequately robust molecular signature, predicting for a radioresponsive phenotype using gene expression and proteomic approaches. In parallel with these developments, functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) can now detect specific biological molecules such as haemoglobin and glucose, so revealing a 3D map of tumour blood flow and metabolism. The key to personalised radiotherapy will be to extend this capability to the proteins of the molecular signature that determine radiosensitivity.

Pretreatment transcriptional profiling for predicting response to neoadjuvant chemoradiotherapy in rectal adenocarcinoma

PURPOSE

Patients presenting with locally advanced rectal cancer currently receive preoperative radiotherapy with or without chemotherapy. Although pathologic complete response is achieved for approximately 10% to 30% of patients, a proportion of patients derive no benefit from this therapy while being exposed to toxic side effects of treatment. Therefore, there is a strong need to identify patients who are unlikely to benefit from neoadjuvant therapy to help direct them toward alternate and ultimately more successful treatment options.

EXPERIMENTAL DESIGN

In this study, we obtained expression profiles from pretreatment biopsies for 51 rectal cancer patients. All patients underwent preoperative chemoradiotherapy, followed by resection of the tumor 6 to 8 weeks posttreatment. Gene expression and response to treatment were correlated, and a supervised learning algorithm was used to generate an original predictive classifier and validate previously published classifiers.

RESULTS

Novel predictive classifiers based on Mandard's tumor regression grade, metabolic response, TNM (tumor node metastasis) downstaging, and normal tissue expression profiles were generated. Because there were only 7 patients who had minimal treatment response (>80% residual tumor), expression profiles were used to predict good tumor response and outcome. These classifiers peaked at 82% sensitivity and 89% specificity; however, classifiers with the highest sensitivity had poor specificity, and vice versa. Validation of predictive classifiers from previously published reports was attempted using this cohort; however, sensitivity and specificity ranged from 21% to 70%.

CONCLUSIONS

These results show that the clinical utility of microarrays in predictive medicine is not yet within reach for rectal cancer and alternatives to microarrays should be considered for predictive studies in rectal adenocarcinoma.

Predictive factors of tumor response after neoadjuvant chemoradiation for locally advanced rectal cancer

PURPOSE

Neoadjuvant chemoradiation followed by surgery is the standard of care for locally advanced rectal cancer. The aim of this study was to correlate tumor response to survival and to identify predictive factors for tumor response after chemoradiation.

METHODS AND MATERIALS

From 1998 to 2008, 168 patients with histologically proven locally advanced adenocarcinoma treated by preoperative chemoradiation before total mesorectal excision were retrospectively studied. They received a radiation dose of 45 Gy with a concomitant 5-fluorouracil (5-FU)-based chemotherapy. Analysis of tumor response was based on lowering of the T stage between pretreatment endorectal ultrasound and pathologic specimens. Overall and progression-free survival rates were correlated with tumor response. Tumor response was analyzed with predictive factors.

RESULTS

The median follow-up was 34 months. Five-year disease-free survival and overall survival rates were, of 44.4% and 74.5% in the whole population, 83.4% and 83.4%, respectively, in patients with pathological complete response, 38.6% and 71.9%, respectively, in patients with tumor downstaging, and 29.1 and 58.9% respectively, in patients with absence of response. A pretreatment carcinoembryonic antigen (CEA) level of <5 ng/ml was significantly independently associated with pathologic complete tumor response (p = 0.019). Pretreatment small tumor size (p = 0.04), pretreatment CEA level of <5 ng/ml (p = 0.008), and chemotherapy with capecitabine (vs. 5-FU) (p = 0.04) were significantly associated with tumor downstaging.

CONCLUSIONS

Downstaging and complete response after CRT improved progression-free survival and overall survival of locally advanced rectal adenocarcinoma. In multivariate analysis, a pretreatment CEA level of <5 ng/ml was associated with complete tumor response. Thus, small tumor size, a pretreatment CEA level of < 5 ng/ml, and use of capecitabine were associated with tumor downstaging.

Molecular prognostic factors in rectal cancer treated by preoperative chemoradiotherapy

The present study evaluated the expression of p53, pRb, hMLH1 and MDM2 prior to preoperative chemoradiotherapy (CRT) in patients with rectal cancer, and attempted to determine any correlation with treatment outcome. Forty-five patients with available pretreatment biopsy tissues and who received preoperative CRT were enrolled in this study. Preoperative CRT consisted of a median 50.4 Gy and 2 cycles of concurrent administration of 5-fluorouracil + leucovorin. Surgery was performed approximately seven weeks after CRT. Protein expression in formalin-fixed paraffin-embedded biopsy specimens was assessed by immunohistochemistry. A positive expression of p53, pRb, hMLH1 and MDM2 was found in 40, 46.7, 40 and 66.7% of the tissue specimens, respectively. The 5-year overall (OS), disease-free (DFS) and locoregional recurrence-free survival (LRFS) rates for patients included in the study were 71.3, 66.1 and 60.9%, respectively. p53 expression presented a significantly different OS (positive vs. negative, 45.8 vs. 86.2%; p=0.02). However, the expression of pRb, hMLH1 and MDM2 was not significant for OS. The expression of p53 was a borderline significant prognostic factor for DFS and for LRFS. Age, p53 and MDM2 expression were significant factors in the multivariate analysis performed for OS with 12 covariates, including 8 clinicopathological parameters and 4 proteins. No significant factor affected DFS or LRFS in the multivariate analysis. We suggest that the expression of p53 is a potential marker of survival. Determinations of this protein expression may be useful for selecting candidates from rectal cancer patients for more tailored treatment.

Rectal cancer and importance of chemoradiation in the treatment

Neoadjuvant chemoradiation is used as a preoperative standard treatment for the majority of patients with Stage II/III rectal cancers and, in attempt to facilitate surgical intervention, reduce the rate of local recurrence and improve overall outcomes in patients suffering from this malignancy. However, this modality results in a wide range of clinical responses. In many cases, a pathological complete response is achieved, while in others, receiving the same form of treatment, the tumor continues to grow. The specific phenotype of the tumor plays a major role in rendering tumor cells a survival advantage to the cytotoxic effects of chemoradiation. Several factors participating in proliferation, cell cycle, apoptosis and hypoxiahave been investigated under a variety of conditions in pre-irradiated tissues and post-irradiated tumors. Mutations in the genes of these pathways have shown to lead to resistance to chemoradiation. This chapter describes colon cancer with emphasis on the molecular mechanisms that may lead to chemoradio-resistance of cells with cytotoxically induced DNA injury in rectal cancer.

Mechanisms of resistance to ionizing radiation in rectal cancer

While patients with breast cancers are not subjected to the adverse side effects of tamoxifen or trastuzumab if their tumors are negative for estrogen, progesterone or Her-2/Neu, neoadjuvant ionizing radiation with concurrent chemotherapeutic agents is administered almost universally to patients with stage II/III rectal cancers. There is, however, a tremendously wide range of response to this preoperative modality from complete pathological response to continuous tumor growth in patients receiving the same form of treatment. The specific phenotype of the tumor plays a major role in rendering tumor cells survival advantage to the cytotoxic effects of chemoradiation. Pathways such as proliferation, cell cycle, apoptosis and hypoxia have been investigated under a variety of conditions in preirradiated tissues and postirradiated tumors. This article reviews the current evidence available to identify a molecular profile predictive of the best response to ionizing radiation.

Biomarkers for response to neoadjuvant chemoradiation for rectal cancer

Locally advanced rectal cancer (LARC) is currently treated with neoadjuvant chemoradiation. Although approximately 45% of patients respond to neoadjuvant therapy with T-level downstaging, there is no effective method of predicting which patients will respond. Molecular biomarkers have been investigated for their ability to predict outcome in LARC treated with neoadjuvant chemotherapy and radiation. A literature search using PubMed resulted in the initial assessment of 1,204 articles. Articles addressing the ability of a biomarker to predict outcome for LARC treated with neoadjuvant chemotherapy and radiation were included. Six biomarkers met the criteria for review: p53, epidermal growth factor receptor (EGFR), thymidylate synthase, Ki-67, p21, and bcl-2/bax. On the basis of composite data, p53 is unlikely to have utility as a predictor of response. Epidermal growth factor receptor has shown promise as a predictor when quantitatively evaluated in pretreatment biopsies or when EGFR polymorphisms are evaluated in germline DNA. Thymidylate synthase, when evaluated for polymorphisms in germline DNA, is promising as a predictive biomarker. Ki-67 and bcl-2 are not useful in predicting outcome. p21 needs to be further evaluated to determine its usefulness in predicting outcome. Bax requires more investigation to determine its usefulness. Epidermal growth factor receptor, thymidylate synthase, and p21 should be evaluated in larger prospective clinical trials for their ability to guide preoperative therapy choices in LARC.

Antitumor bioactivity of adenovirus-mediated p27mt in colorectal cancer cell line SW480

AIM: To explore the antitumor bioactivity of adenovirus-mediated mutant type p27^kip1 gene in a colorectal cancer cell line SW480.

METHODS: We constructed recombinant adenovirus vector expressing a mutant type p27^kip1 gene (ad-p27mt), with mutation of Thr-187/Pro-188 (ACGCCC) to Met-187/Ile-188 (ATGATC), and transduced into SW480 cells. Then we detected expression of p27, Bcl-2 and Bax protein in the transductants by Western blotting, cell cycle of transductants by a digital flow cytometric system, migrating potential with Boyden Chamber and SW480 tumor cell growth inhibition in vitro and in vivo.

RESULTS: We found that a recombinant adenovirus vector of expressing ad-p27mt, with mutation of Thr-187/Pro-188 (ACGCCC) to Met-187/Ile-188 (ATGATC) has potent inhibition of SW480 tumor cell growth in vitro and in vivo. Furthermore, ad-p27mt induced cell apoptosis via regulating bax and bcl-2 expressions, and G₁/S arrest in SW480 cells and inhibited cell migration.

CONCLUSION: ad-p27mt has a strong anti-tumor bioactivity and has the potential to develop into new therapeutic agents for colorectal cancer.

Combined analysis of VEGF and EGFR predicts complete tumour response in rectal cancer treated with preoperative radiotherapy

The ability to predict complete pathologic response or sensitivity to radiation before treatment would have a significant impact on the selection of patients for preoperative radiotherapy or chemo-radiation therapy schedules. The aim of this study was to determine the value of epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), p53, Bcl-2 and apoptosis protease-activating factor-1 (APAF-1) as predictors of complete pathologic tumour regression in patients undergoing preoperative radiotherapy for advanced rectal cancer. Pretreatment tumour biopsies from predominantly cT3 patients undergoing a preoperative high-dose-rate brachytherapy protocol were immunostained for EGFR, VEGF, p53, Bcl-2 and APAF-1. Immunoreactivity was evaluated by three pathologists. Cut-off scores for tumour marker positivity were obtained by receiver-operating characteristic (ROC) curve analysis. The association of marker expression with complete pathologic response was analysed in univariate and multivariable analysis. Multi-marker phenotypes of the independent protein markers were evaluated. In multivariable analysis, loss of VEGF (P-value=0.009; odds ratio (OR) (95% CI)=0.24 (0.08–0.69)) and positive EGFR (P-value=0.01; OR (95% CI)=3.82 (1.37–10.6)) both demonstrated independent predictive value for complete pathologic response. The odds of complete response were 12.8 for the multi-marker combination of VEGF-negative and EGFR-positive tumours. Of the 34 EGFR-negative- and VEGF-positive cases, 32 (94.1%) had no complete pathologic response. The combined analysis of VEGF and EGFR is predictive of complete pathologic response in patients undergoing preoperative radiotherapy. In addition, the findings of this study have identified a subgroup of simultaneous EGFR-negative and VEGF-positive patients who are highly resistant to radiotherapy and should perhaps be considered candidates for innovative neoadjuvant combined modalities.