Prognostic Markers of Local Relapse in Rectal Cancer: Are We Any Further Forward?

Synchronized release of Doxil and Nutlin-3 by remote degradation of polysaccharide matrices and its possible use in the local treatment of colorectal cancer

A novel approach to the prevention of colorectal cancer (CRC) recurrence by the local, luminal application of the combined therapies: Nutlin-3 (NUT) and the liposomal preparation of doxorubicin, Doxil(*) (Doxil) is presented here. The two drug entities were loaded into calcium alginate beads, engineered to erode upon exposure to a de-crosslinking agent, to allow for the controlled, concomitant release of the two. The synchronized release-driven improved cytotoxicity of NUT and Doxil was tested in vitro in RKO (wild-type p53) and HT-29 (mutant p53) CRC cells, by measuring intracellular expression of p53, p21 and Mdm2, as well as monitoring cell proliferation and viable cell numbers. NUT treatment alone was identified to be cytotoxic exclusively towards RKO cells. However, coadministration of NUT enhanced Doxil's anti-proliferative effects and cell death induction in a synergistic manner in both cell types. It was also identified that combinatorial treatment in a wt p53 context affected the p53 pathway by elevating the expression of p53 and its target p21. The capability of the formulation to erode in the presence of a de-crosslinking agent was demonstrated in vivo in the cecum of the anesthetized rat using indomethacin as a poorly water-soluble PK probe.

Unique considerations in the patient with rectal cancer

In the past two decades, substantial progress has been made in the adjuvant management of colorectal cancer. Chemotherapy has improved overall survival in patients with node-positive (N+) disease. In contrast with colon cancer, which has a low incidence of local recurrence, patients with rectal cancer have a higher incidence requiring the addition of pelvic radiation therapy (chemoradiation). Patients with rectal cancer have a number of unique management considerations: for example, the role of short-course radiation, whether postoperative adjuvant chemotherapy is necessary for all patients, and if the type of surgery following chemoradiation should be based on the response rate. More accurate imaging techniques and/or molecular markers may help identify patients with positive pelvic nodes to reduce the chance of overtreatment with preoperative therapy. Will more effective systemic agents both improve the results of radiation as well as modify the need for pelvic radiation? This review will address these and other controversies specific to patients with rectal cancer.

A combined strategy of SAGE and quantitative PCR Provides a 13-gene signature that predicts preoperative chemoradiotherapy response and outcome in rectal cancer

PURPOSE

Preoperative chemoradiotherapy (CRT) is the treatment of choice for rectal cancer (RC), but half of the patients do not respond, suffer unnecessary toxicities, and surgery delays. We aimed to develop a model that could predict a clinically meaningful response to CRT by using formalin-fixed paraffin-embedded (FFPE) biopsies.

EXPERIMENTAL DESIGN

We first carried out an exploratory screening of candidate genes by using SAGE technology to evaluate dynamic changes in the RC transcriptome in selected refractory patients before and after CRT. Next, 53 genes (24 from SAGE and 29 from the literature) were analyzed by qPCR arrays in FFPE initial biopsies from 94 stage II/III RC patients who were preoperatively treated with CRT. Tumor response was defined by using Dworak's tumor regression grade (2-3-4 vs. 0-1). Multivariate Cox methods and stepwise algorithms were applied to generate an optimized predictor of response and outcome.

RESULTS

In the training cohort (57 patients), a 13-gene signature predicted tumor response with 86% accuracy, 87% sensitivity, and 82% specificity. In a testing cohort (37 patients), the model correctly classified 6 of 7 nonresponders, with an overall accuracy of 76%. A signature-based score identified patients with a higher risk of relapse in univariate (3-year disease-free survival 64% vs. 90%, P = 0.001) and multivariate analysis (HR = 4.35 95% CI: 1.2-15.75, P = 0.02), in which it remained the only statistically significant prognostic factor.

CONCLUSIONS

A basal 13-gene signature efficiently predicted CRT response and outcome. Multicentric validation by the GEMCAD collaborative group is currently ongoing. If confirmed, the predictor could be used to improve patient selection in RC studies.

Chemoradiation for rectal cancer: rationale, approaches, and controversies

The standard adjuvant treatment of cT3 and/or N+ rectal cancer is preoperative chemoradiation. However, there are many controversies regarding this approach. These controversies include the role of short course radiation, whether postoperative adjuvant chemotherapy is necessary for all patients, and if the type of surgery following chemoradiation should be based on the response rate. More accurate imaging techniques and/or molecular markers may help identify patients with positive pelvic nodes to reduce the chance of overtreatment with preoperative therapy. Will more effective systemic agents both improve the results of radiation, as well as modify the need for pelvic radiation? These questions and others remain active areas of clinical investigation.

Combined modality therapy for rectal cancer

The standard adjuvant treatment for cT3 and/or N+ rectal cancer is preoperative chemoradiation. However, there are many controversies regarding this approach. These include the role of short course radiation, whether postoperative adjuvant chemotherapy necessary for all patients and whether the type of surgery after chemoradiation should be based on the response rate. More accurate imaging techniques and/or molecular markers may help identify patients with positive pelvic nodes to reduce the chance of overtreatment with preoperative therapy. Will more effective systemic agents both improve the results of radiation as well as modify the need for pelvic radiation? These questions and others remain active areas of clinical investigation.

miR-192/miR-215 influence 5-fluorouracil resistance through cell cycle-mediated mechanisms complementary to its post-transcriptional thymidilate synthase regulation

Thymidylate synthase (TYMS) is a target of the most widely used chemotherapeutic agents against gastrointestinal malignancies, the fluoropyrimidine-based therapy. TYMS expression levels have been identified as predictive biomarkers for 5-fluoruracil (FU) response in colorectal cancer, but their clinical utility remains controversial. The complexity of fluoropyrimidine response must require more mechanisms that currently have not been completely elucidated. In this context, microRNAs (miRNA) may play a role in modulating chemosensitivity. By carrying out an in silico analysis coupled to experimental validation, we detected that miR-192 and miR-215 target TYMS expression in colorectal cancer cell lines. However, downregulation of TYMS by these miRNAs does not sensitize colorectal cancer cell lines to FU treatment. The overexpression of miR-192/215 significantly reduces cell proliferation by targeting cell cycle progression. This effect was partially associated with p53 status, because reduction of cell proliferation and cell cycle arrest was associated with p21 and p27 induction. The decrease of S-phase cells by these miRNAs mitigates the effects of S phase-specific drugs and suggests that other mechanisms different from TYMS overexpression are essential to direct FU resistance. Finally, ectopic expression of miR-192/215 might have stronger impact to predict FU response than TYMS inhibition. Prospective studies to elucidate the role of these miRNAs as predictive biomarkers to FU are necessary.

Colorectal cancer

Substantial progress has been made in colorectal cancer in the past decade. Screening, used to identify individuals at an early stage, has improved outcome. There is greater understanding of the genetic basis of inherited colorectal cancer and identification of patients at risk. Optimisation of surgery for patients with localised disease has had a major effect on survival at 5 years and 10 years. For rectal cancer, identification of patients at greatest risk of local failure is important in the selection of patients for preoperative chemoradiation, a strategy proven to improve outcomes in these patients. Stringent postoperative follow-up helps the early identification of potentially radically treatable oligometastatic disease and improves long-term survival. Treatment with adjuvant fluoropyrimidine for colon and rectal cancers further improves survival, more so in stage III than in stage II disease, and oxaliplatin-based combination chemotherapy is now routinely used for stage III disease, although efficacy must be carefully balanced against toxicity. In stage II disease, molecular markers such as microsatellite instability might help select patients for treatment. The integration of targeted treatments with conventional cytotoxic drugs has expanded the treatment of metastatic disease resulting in incremental survival gains. However, biomarker development is essential to aid selection of patients likely to respond to therapy, thereby rationalising treatments and improving outcomes.

Lymphatic vessel density as predictive marker for the local recurrence of rectal cancer

PURPOSE

This study identified possible factors affecting the frequency of local recurrence of rectal cancer, focusing on lymphangiogenesis as a predictor.

METHODS

We examined 352 primary rectal cancer cases and 34 local recurrent specimens by lymphatic hyaluronan receptor. The lymphangiogenesis of all specimens was evaluated by measuring by lymphatic vessel density and other clinicopathologic factors.

RESULTS

A multivariate analysis using the Cox proportional hazard model showed that lymphatic vessel density, lymph node metastasis, depth of invasion, and lymphatic invasion were significant independent predictive factors of local recurrence; lymphatic vessel density was the strongest predictor. In addition, a significant correlation was found between the lymphatic vessel density of the primary rectal cancer and the corresponding local recurrent cases.

CONCLUSIONS

We suggest that rectal cancers, which have active lymphangiogenesis, also demonstrate a greater potential for local recurrence, and the lymphatic vessel density of surgical specimens is an independent risk factor and a valuable predictive factor for the local recurrence of rectal cancer.

Prediction of treatment outcome by CD44v6 after total mesorectal excision in locally advanced rectal cancer

BACKGROUND

The purpose of this study was to investigate the significance of CD44 variant 6 (CD44v6) in predicting the treatment outcome of locally advanced adenocarcinoma of the rectum after total mesorectal excision (TME).

METHODS

Expression of CD44v6 protein was detected using immunohistochemistry in 179 patients with pathologically confirmed stage II or III rectal adenocarcinoma. All patients were treated with TME, and neither neoadjuvant nor adjuvant radiotherapy were used. The correlation between the expression of CD44v6 and other disease-related characteristics with treatment outcome was investigated.

RESULTS

The 5-year overall survival and disease-free survival rates were 66.75% and 65.77%, respectively, and the overall locoregional recurrence rate was 8.13% for the entire group of patients. CD44v6 was present in 41.9% of all patients. Multivariate analysis revealed that CD44v6 status and pelvic nodal metastasis were independent risk factors for the rate of distant metastases (P = 0.036 and 0.035, respectively), disease-free survival (P = 0.009 and 0.016, respectively), and overall survival (P = 0.048 and 0.034, respectively). Lymph node metastasis was the only independent risk factor for locoregional recurrence (P = 0.048), and a trend was found for CD44v6 on predicting the locoregional recurrence (P = 0.06) with both stage II and III diseases. CD44v6 is significantly associated with locoregional recurrence in stage III rectal cancer (hazard ratio 6.02, 95% confidence interval 1.25-29.0; P = 0.018), and the overall locoregional recurrence was significantly higher for patients with positive expression of CD44v6 than for those with negative expression (17.63% vs 6.62%; P = 0.026).

CONCLUSION

CD44v6 expression in cancer cells is a sensitive marker for predicting the treatment outcome in patients with stage II and III adenocarcinoma of the rectum after TME and may be used to determine the necessity of adjuvant treatment. However, further investigations are needed to determine the clinical application of CD44v6 and its reliability.

Patients with curative resection of cT3-4 rectal cancer after preoperative radiotherapy or radiochemotherapy: does anybody benefit from adjuvant fluorouracil-based chemotherapy? A trial of the European Organisation for Research and Treatment of Cancer Radiation Oncology Group

PURPOSE

European Organisation for Research and Treatment of Cancer (EORTC) trial 22921 compared adjuvant fluorouracil-based chemotherapy (CT) to no adjuvant treatment in a 2 x 2 factorial trial with randomization for preoperative (chemo)radiotherapy in patients with resectable T3-4 rectal cancer. The results showed no significant impact of adjuvant CT on progression-free or overall survival, although a difference seemed to emerge at approximately, respectively, 2 and 5 years after the start of preoperative treatment. We further explored the data with the aim of refining our understanding of the long-term results.

PATIENTS AND METHODS

Data of 785 of the 1,011 randomly assigned patients who whose disease was M0 at curative surgery were used. Using meta-analytic methods, we investigated the homogeneity of the effect of adjuvant CT on the time to relapse or death after surgery (disease-free survival [DFS]) and survival in patient subgroups.

RESULTS

Although there was no statistically significant impact of adjuvant CT on DFS for the whole group (P > .5), the treatment effect differed significantly between the ypT0-2 and the ypT3-4 patients (heterogeneity P = .009): only the ypT0-2 patients seemed to benefit from adjuvant CT (P = .011). The same pattern was observed for overall survival.

CONCLUSION

Exploratory analyses suggest that only good-prognosis patients (ypT0-2) benefit from adjuvant CT. This could explain why, in the whole group, the progression-free and overall survival diverged only after the poor-prognosis patients (ypT3-4) had experienced treatment failure. Patients in whom no downstaging was achieved did not benefit. This also suggests that the same prognostic factors may drive both tumor sensitivity for the primary treatment and long-term clinical benefit from further adjuvant CT.

Study on the relationship between lymphatic vessel density and distal intramural spread of rectal cancer

BACKGROUND

The smallest safe margin of distal clearance for lower rectal cancer is very important for the operation. In a previous study, a few factors were found to play a role in distal intramural spread (DIS), but there are few data regarding the influence of lymphangiogenesis. We studied the relationship between lymphatic vessel density (LVD) and DIS of rectal cancer, analyzing the probable value of LVD in determining the length of distal resection of lower rectal cancer.

METHODS

Nine-two patients who had undergone curative resection of lower rectal cancer were included. The length of DIS, LVD and other clinicopathological factors were evaluated. Immunohistochemical lymphatic vessel staining with LYVE-1 (lymphatic vessel endothelial hyaluronan receptor) were performed to detect the LVD.

RESULTS

44 cases had DIS (range 0.1-2.44, mean 0.31 cm), and cancer emboli were the most common modalities of DIS. The LVD of a peritumoral lesion was significantly higher than that of an intratumoral lesion; the LVD of the DIS subgroup was significantly higher than that of the no DIS subgroup, and the LVD of the 2 subgroups was significantly higher than that of normal rectal tissue. A significant correlation was shown by a rank correlation test between the length of DIS and the LVD at the periphery of the rectal cancer (n = 44, r = 0.755, p < 0.01). The LVD was also related to the extent of infiltration, lymphatic invasion and lymph node metastases.

CONCLUSIONS

Lymphangiogenesis plays an important role in rectal cancer cell metastasis and patients with a higher LVD have a better prognosis. The LVD is closely correlated with DIS. These findings may be helpful in determining the distal clearance length of rectal cancer.