Epidermal growth factor receptor gene copy number, K-ras mutation and pathological response to preoperative cetuximab, 5-FU and radiation therapy in locally advanced rectal cancer

Circulating Biomarkers in Predicting Pathological Response to Neoadjuvant Therapy for Colorectal Cancer

Circulating biomarkers show promise in the management of many cancers. They have become the novel non-invasive approach to complement the current strategies in colorectal cancer (CRC) management. Their ability in guiding diagnosis, evaluating response to treatment, screening and prognosis is phenomenal, especially when it comes to their minimally invasive nature. These “liquid biopsies,” which show potential for replacing invasive surgical biopsies, provide useful information on the primary and metastatic disease by providing an insight into cancer biology. Analysis of blood and body fluids for circulating tumour DNA (ctDNA), carcinoembryonic antigen (CEA), circulating tumour cells (CTC), or circulating micro RNA (miRNA) shows potential for improving CRC management. Recognizing a predictive model to assess response to neoadjuvant chemotherapy would help in better patient selection. This review was conducted with the aim of outlining the use of circulatory biomarkers in current practice and their effectiveness in the management of patients having CRC with a focus on response to neoadjuvant therapy.

The Addition of EGFR Inhibitors in Neoadjuvant Therapy for KRAS-Wild Type Locally Advanced Rectal Cancer Patients: A Systematic Review and Meta-Analysis

Background

Patients with locally advanced rectal cancer (LARC) are at higher risk of local and distant recurrence and are thus more vulnerable to metastatic diseases. Neoadjuvant chemoradiotherapy (nCRT) and subsequent curative resection with total mesorectal excision (TME) followed by adjuvant chemotherapy have been recommended by the National Comprehensive Cancer Network (NCCN) guidelines as standard of care for LARC patients. However, the efficacy of the addition of epidermal growth factor receptor (EGFR) inhibitors in kirsten rat sarcoma viral oncogene (KRAS)-wild type LARC patients remains uncertain.

Materials

PubMed, Embase, and Web of Science were searched to retrieve records on the application of EGFR inhibitors in a neoadjuvant setting for LARC patients. pCR was used as surrogate endpoint to perform data synthesis in a single-arm setting.

Results

Ten cohorts covering 540 subjects were eligible in this systematic review. The pooled pCR rate for EGFR inhibitors was 15% (95% confidence interval (95% CI), 11-20%; I² = 55.2%); the pooled estimates of Grade 3/4 diarrhea, Grade 3/4 hand-foot syndrome, Grade 3/4 acneiform rash were 17% (95% CI, 4-34%; I² = 93.3%), 2% (95% CI, 0-5%; I² = 13.7%), and 15% (95% CI, 9-22%; I² = 65.4%), respectively.

Conclusion

The addition of EGFR inhibitors in the nCRT for KRAS-wild type LARC patients provides comparable efficacy and acceptable safety. However, the results should be interpreted cautiously due to the small amount of relevant data and need further confirmation by more future studies.

Locally advanced rectal cancer: The past, present, and future

From a series of clinical trials in the last several decades, current treatment paradigms for locally advanced rectal cancer include: (1) preoperative long-course radiotherapy (RT) combined with radiosensitizing chemotherapy; (2) preoperative short-course RT alone followed by adjuvant postoperative chemotherapy; and (3) total neoadjuvant therapy with induction chemotherapy followed by chemoradiotherapy. Other strategies under active investigation in both institutional and cooperative trials include neoadjuvant chemotherapy alone without RT in select patients, total neoadjuvant therapy, watchful waiting after a clinical complete response as an alternative to surgical resection, and the use of different chemotherapeutic and targeted agents. The focus of this review is on established and novel therapeutic strategies for locally advanced rectal cancer.

Association of tumor differentiation and prognosis in patients with rectal cancer undergoing neoadjuvant chemoradiation therapy

Background and objective

Neoadjuvant chemoradiation therapy (NCRT) followed by radical resection has been a common practice for patients with locally advanced rectal cancer. This study aimed to analyse the association of tumor differentiation and prognosis in rectal-cancer patients undergoing NCRT.

Methods

Patients with locally advanced, non-mucinous rectal cancer who underwent NCRT followed by radical resection between 2007 and 2017 were identified from an electronic health record system at the Sixth Affiliated Hospital of Sun Yat-sen University (Guangzhou, China). Multivariable logistic regression and multivariate Cox regression were performed to analyse the association of response to NCRT and survival with clinicopathological characteristics of all these patients.

Results

We identified 325 patients (241 males and 84 females; mean age, 54.4 ± 11.2 years) who underwent NCRT followed by radical resection, including 26 (8.0%) with poorly-differentiated rectal cancer, 182 (56.0%) with moderately-differentiated cancer and 117 (36.0%) with well differentiated cancer. Propensity score matching analysis and multivariable logistic regression analysis results showed that tumor differentiation was significantly associated with response to NCRT. In the poor differentiation and non-poor differentiation groups, the 3-year overall survival (OS) rates were 74.6 and 93.5%, respectively, whereas the 3-year local recurrence rates were 18.6 and 3.7%, respectively. Multivariable Cox regression analyses revealed that poor differentiation was an independent risk factor for local recurrence and OS.

Conclusions

Among the patients with locally advanced, non-mucinous rectal cancer, the patients with poorly-differentiated cancer who underwent NCRT had a worse response to NCRT and poorer prognosis than those with moderately- and well-differentiated diseases.

Phase II Study of Preoperative Treatment with External Radiotherapy Plus Panitumumab in Low-Risk, Locally Advanced Rectal Cancer (RaP Study/STAR-03)

BACKGROUND

Treatment with fluoropyrimidines and concomitant long-course external radiotherapy (RTE) is the standard of care in locally advanced rectal cancer (LARC) preoperative chemoradiation. A randomized phase II study (RaP/STAR-03) was conducted that aimed to evaluate the activity and safety of the monoclonal antibody anti-epidermal growth factor receptor panitumumab as a single agent in combination with radiotherapy in low-risk LARC preoperative treatment.

MATERIALS AND METHODS

Patients had adenocarcinoma of the mid-low rectum, cT3N- or cT2-T3N+, KRAS wild-type status, and negative circumferential radial margin. Panitumumab was administered concomitant to RTE. Rectal surgery was performed 6-8 weeks after the end of preoperative treatment. The adjuvant chemotherapy regimen was FOLFOX. The primary endpoint was the pathologic complete response (pCR) rate. The sample size was calculated using Simon's two-stage design. A pCR of 16% was considered to qualify the experimental treatment for further testing.

RESULTS

Ninety-eight patients were enrolled in 13 Italian centers from October 2012 to October 2015. Three panitumumab infusions were administered in 92 (93.4%) patients. The RTE compliance was median dose 50.4 Gy; ≥28 fractions in 82 (83.7%) patients. Surgical treatment was performed in 92 (93.9%) patients, and no severe intraoperative complications were observed. A pCR was observed in 10 (10.9%) patients (95% confidence interval, 4.72%-17.07%). Pathological downstaging occurred in 45 (45.9%) patients. Grade 3 toxicities were observed in 22 (22.3%) patients, and the common adverse events were skin rash in 16 (16.3%) patients. No grade 4 toxicities were reported.

CONCLUSION

The pCR rate (our primary endpoint), at only 10.9%, did not reach the specified level considered suitable for further testing. However, the analysis showed a good toxicity profile and compliance to concomitant administration of panitumumab and RTE in preoperative treatment of LARC. The pCR evaluation in all wild-type RAS is ongoing.

IMPLICATIONS FOR PRACTICE

The aim of the RaP/STAR-03 study was to evaluate the activity and safety of monoclonal antibody anti-epidermal growth factor receptor (EGFR) panitumumab as a single agent without chemotherapy in low-risk, locally advanced rectal cancer (LARC) preoperative treatment. Nevertheless, the use of panitumumab in combination with radiotherapy in preoperative treatment in patients with KRAS wild type and low-risk LARC did not reach the pathologic complete response primary endpoint. This study showed a good toxicity profile and compliance to combination treatment. Further analysis of NRAS and BRAF on tissue and circulating levels of the EGFR ligands and vascular factors (soluble vascular endothelial growth factor, E-selectin) may provide insight on the potential molecular pathways involved in the anti-EGFR response.

The efficacy of adding targeted agents to neoadjuvant therapy for locally advanced rectal cancer patients: a meta-analysis

Patients with locally advanced rectal cancer (LARC) are at tremendous risk of metastatic diseases. To improve the prognoses of LARC patients, the efficacy of adding targeted agents to neoadjuvant therapy has been investigated by many researchers but remains controversial. A literature search of relevant databases was conducted through December 2016, 804 studies were identified and 32 investigations were ultimately included. A total of 1196 patients from 31 cohorts of 29 studies were eligible for quantitative synthesis in this single‐arm setting meta‐analysis. As pathologic complete response (pCR) shows promise as a prognosis indicator, we focused on pCR rates to evaluate whether adding targeted agents to neoadjuvant therapies improves the outcome of LARC patients. In our study, we revealed pooled estimates of pCR of 27% (95%CI, 21–34%) and 14% (95%CI, 9–21%) for bevacizumab‐relevant cohorts and cetuximab‐relevant cohorts, respectively. The safety of adding targeted agents to neoadjuvant therapy was also evaluated by pooling the data of Grade 3/4 toxicity. In conclusion, our study revealed that adding bevacizumab to the neoadjuvant therapy regimens provides appreciable pCR for LARC patients. Meanwhile, the efficacy of cetuximab remains inconclusive, RCTs with larger scale and better study design that stress more on mutational status are needed.

Drug Combinations in Preoperative Chemoradiation for Rectal Cancer

Preoperative radiotherapy has an accepted role in reducing the risk of local recurrence in locally advanced resectable rectal cancer, particularly when the circumferential resection margin is breached or threatened, according to magnetic resonance imaging. Fluoropyrimidine-based chemoradiation can obtain a significant down-sizing response and a curative resection can then be achieved. Approximately, 20% of the patients can also obtain a pathological complete response, which is associated with less local recurrences and increased survival. Patients who achieve a sustained complete clinical response may also avoid radical surgery. In unresectable or borderline resectable tumors, around 20% of the patients still fail to achieve a sufficient down-staging response with the current chemoradiation schedules. Hence, investigators have aspired to increase pathological complete response rates, aiming to improve curative resection rates, enhance survival, and potentially avoid mutilating surgery. However, adding additional cytotoxic or biological agents have not produced dramatic improvements in outcome and often led to excess surgical morbidity and higher levels of acute toxicity, which effects on compliance and in the global efficacy of chemoradiation.

Germline and somatic genetic predictors of pathological response in neoadjuvant settings of rectal and esophageal cancers: systematic review and meta-analysis

Oncologists have pointed out an urgent need for biomarkers that can be useful for clinical application to predict the susceptibility of patients to preoperative therapy. This review collects, evaluates and combines data on the influence of reported somatic and germline genetic variations on histological tumor regression in neoadjuvant settings of rectal and esophageal cancers. Five hundred and twenty-seven articles were identified, 204 retrieved and 61 studies included. Among 24 and 14 genetic markers reported for rectal and esophageal cancers, respectively, significant associations in meta-analyses were demonstrated for the following markers. In rectal cancer, major response was more frequent in carriers of the TYMS genotype 2 R/2 R-2 R/3 R (rs34743033), MTHFR genotype 677C/C (rs1801133), wild-type TP53 and KRAS genes. In esophageal cancer, successful therapy appeared to correlate with wild-type TP53. These results may be useful for future research directions to translate reported data into practical clinical use.

The multidisciplinary approach to the treatment of rectal cancer: 2015 update

The multidisciplinary approach to the management of rectal cancer continues to evolve with developments in surgery, radiation therapy as well as systemic chemotherapy. Refinement of surgical techniques to improve organ preservation, selective use of neoadjuvant (or adjuvant) therapies, improvements in staging modalities and emerging criteria for the selection of tailored therapies are some of the advancements made over the last three decades. In addition, neoadjuvant treatment alternatives, multimodality sequencing and adaptive therapies based on treatment response continue to be a subject of clinical investigation. The current article reviews the salient topics related to the multidisciplinary treatment of resectable rectal cancer.

Phase I/II study of neoadjuvant bevacizumab, erlotinib and 5-fluorouracil with concurrent external beam radiation therapy in locally advanced rectal cancer

BACKGROUND

To determine the maximal tolerated dose of erlotinib when added to 5-fluorouracil (5-FU) chemoradiation and bevacizumab and safety and efficacy of this combination in patients with locally advanced rectal cancer.

PATIENTS AND METHODS

Patients with Magnetic resonance imaging (MRI) or ultrasound defined T3 or T4 adenocarcinoma of the rectum and without evidence of metastatic disease were enrolled. Patients received infusional 5-FU 225 mg/M2/day continuously, along with bevacizumab 5 mg/kg days 14, 1, 15 and 29. Standard radiotherapy was administered to 50.4 Gy in 28 fractions. Erlotinib started at a dose of 50 mg orally daily and advanced by 50 mg increments in the subsequent cohort. Open total mesorectal excision was carried out 6-9 weeks following the completion of chemoradiation.

RESULTS

Thirty-two patients received one of three dose levels of erlotinib. Erlotinib dose level of 100 mg was determined to be the maximally tolerated dose. Thirty-one patients underwent resection of the primary tumor, one refused resection. Twenty-seven patients completed study therapy, all of whom underwent resection. At least one grade 3-4 toxicity occurred in 46.9% of patients. Grade 3-4 diarrhea occurred in 18.8%. The pathologic complete response (pCR) for all patients completing study therapy was 33%. With a median follow-up of 2.9 years, there are no documented local recurrences. Disease-free survival at 3 years is 75.5% (confidence interval: 55.1-87.6%).

CONCLUSIONS

Erlotinib added to infusional 5-FU, bevacizumab and radiation in patients with locally advanced rectal cancer is relatively well tolerated and associated with an encouraging pCR.

Chromosomal instability portends superior response of rectal adenocarcinoma to chemoradiation therapy

BACKGROUND

Persistent chromosome segregation errors represent a conspicuous feature of human neoplasms. It is widely accepted that this chromosomal instability is associated with poor prognosis; however, its effect on therapeutic response is a matter of conjecture.

METHODS

Here, the role of chromosome segregation errors in the response of patients with rectal adenocarcinoma to chemoradiation therapy (CRT) was examined. Pretreatment samples from 62 patients were surveyed for evidence of chromosome mis-segregation and mis-segregation frequency was correlated to the pathological response to CRT as determined by the tumor regression grade after surgical resection of irradiated tumors.

RESULTS

Surprisingly, it was found that errors in chromosome segregation predicted enhanced pathological response of rectal adenocarcinoma to CRT (odds ratio, 3.9; P = .02). Furthermore, tumor response inversely correlated with the frequency of cells that exhibited segregation errors during anaphase (correlation coefficient, 0.94; P < .05). Strikingly, elevated chromosome mis-segregation combined with decreased levels of the DNA damage repair protein Mre11 portended a markedly enhanced response (odds ratio, 54.0; P = .008).

CONCLUSIONS

The results of the current study demonstrate that chromosomal instability is a favorable predictor of response to CRT in patients with locally invasive rectal adenocarcinoma. Therefore, the authors propose that downstream structural damage to chromosomes resulting from segregation errors potentiates the effect of DNA-damaging therapies and synergizes with deficiencies in the DNA repair machinery. This work identifies a novel mechanistic marker that foretells treatment response to CRT and suggests that concomitant targeting of whole-chromosome segregation and DNA repair may constitute an effective therapeutic strategy.

Preoperative radiation therapy with concurrent capecitabine, bevacizumab, and erlotinib for rectal cancer: a phase 1 trial

PURPOSE

The goal of this phase 1 trial was to determine the maximum tolerated dose (MTD) of concurrent capecitabine, bevacizumab, and erlotinib with preoperative radiation therapy for rectal cancer.

METHODS AND MATERIALS

Patients with clinical stage II to III rectal adenocarcinoma, within 12 cm from the anal verge, were treated in 4 escalating dose levels, using the continual reassessment method. Patients received preoperative radiation therapy with concurrent bevacizumab (5 mg/kg intravenously every 2 weeks), erlotinib, and capecitabine. Capecitabine dose was increased from 650 mg/m(2) to 825 mg/m(2) orally twice daily on the days of radiation therapy; erlotinib dose was increased from 50 mg orally daily in weeks 1 to 3, to 50 mg daily in weeks 1 to 6, to 100 mg daily in weeks 1 to 6. Patients underwent surgery at least 9 weeks after the last dose of bevacizumab.

RESULTS

A total of 19 patients were enrolled, and 18 patients were considered evaluable. No patient had grade 4 acute toxicity, and 1 patient had grade 3 acute toxicity (hypertension). The MTD was not reached. All 18 evaluable patients underwent surgery, with low anterior resection in 7 (39%), proctectomy with coloanal anastomosis in 4 patients (22%), posterior pelvic exenteration in 1 (6%), and abdominoperineal resection in 6 (33%). Of the 18 patients, 8 (44%) had pathologic complete response, and 1 had complete response of the primary tumor with positive nodes. Three patients (17%) had grade 3 postoperative complications (ileus, small bowel obstruction, and infection). With a median follow-up of 34 months, 1 patient developed distant metastasis, and no patient had local recurrence or died. The 3-year disease-free survival was 94%.

CONCLUSIONS

The combination of preoperative radiation therapy with concurrent capecitabine, bevacizumab, and erlotinib was well tolerated. The pathologic complete response rate appears promising and may warrant further investigation.

The status of targeted agents in the setting of neoadjuvant radiation therapy in locally advanced rectal cancers

Radiotherapy has a longstanding and well-defined role in the treatment of resectable rectal cancer to reduce the historically high risk of local recurrence. In more advanced borderline or unresectable cases, where the circumferential resection margin (CRM) is breached or threatened according to magnetic resonance imaging (MRI), despite optimized local multimodality treatment and the gains achieved by modern high quality total mesorectal excision (TME), at least half the patients fail to achieve sufficient downstaging with current schedules. Many do not achieve an R0 resection. In less locally advanced cases, even if local control is achieved, this confers only a small impact on distant metastases and a significant proportion of patients (30-40%) still subsequently develop metastatic disease. In fact, distant metastases have now become the predominant cause of failure in rectal cancer. Therefore, increasing the intensity and efficacy of chemotherapy and chemoradiotherapy by integrating additional cytotoxics and biologically targetted agents seems an appealing strategy to explore-with the aim of enhancing curative resection rates and improving distant control and survival. However, to date, we lack validated biomarkers for these biological agents apart from wild-type KRAS. For cetuximab, the appearance of an acneiform rash is associated with response, but low levels of magnesium appear more controversial. There are no molecular biomarkers for bevacizumab. Although some less invasive clinical markers have been proposed for bevacizumab, such as circulating endothelial cells (CECS), circulating levels of VEGF and the development of overt hypertension, these biomarkers have not been validated and are observed to emerge only after a trial of the agent. We also lack a simple method of ongoing monitoring of 'on target' effects of these biological agents, which could determine and pre-empt the development of resistance, prior to radiological and clinical assessessments or even molecular imaging. These shortcomings probably explain our current relative lack of success in the arena of combining these agents with chemoradiation.

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.

Impact of KRAS, BRAF and PI3KCA mutations in rectal carcinomas treated with neoadjuvant radiochemotherapy and surgery

BACKGROUND

Conventional treatment for locally advanced rectal cancer usually combines neoadjuvant radiochemotherapy and surgery. Until recently, there have been limited predictive factors (clinical or biological) for rectal tumor response to conventional treatment. KRAS, BRAF and PIK3CA mutations are commonly found in colon cancers. In this study, we aimed to determine the mutation frequencies of KRAS, BRAF and PIK3CA and to establish whether such mutations may be used as prognostic and/or predictive factors in rectal cancer patients.

METHODS

We retrospectively reviewed the clinical and biological data of 98 consecutive operated patients between May 2006 and September 2009. We focused in patients who received surgery in our center after radiochemotherapy and in which tumor samples were available.

RESULTS

In the 98 patients with a rectal cancer, the median follow-up time was 28.3 months (4-74). Eight out of ninety-eight patients experienced a local recurrence (8%) and 17/98 developed distant metastasis (17%). KRAS, BRAF and PIK3CA were identified respectively in 23 (23.5%), 2 (2%) and 4 (4%) patients. As described in previous studies, mutations in KRAS and BRAF were mutually exclusive. No patient with local recurrence exhibited KRAS or PIK3CA mutation and one harbored BRAF mutation (12.5%). Of the seventeen patients with distant metastasis (17%), 5 were presenting KRAS mutation (29%), one BRAF (5%) and one PIK3CA mutation (5%). No relationship was seen between PIK3CA, KRAS or BRAF mutation and local or distant recurrences.

CONCLUSION

The frequencies of KRAS, BRAF and PIK3CA mutations in our study were lower than the average frequencies reported in colorectal cancers and no significant correlation was found between local/distant recurrences and KRAS, BRAF or PIK3CA mutations. Future studies with greater number of patients, longer follow-up time and greater power to predict associations are necessary to fully understand this relationship.

Radiotherapy response in microsatellite instability related rectal cancer

Preoperative radiotherapy may improve the resectability and subsequent local control of rectal cancers. However, the extent of radiation induced regression in these tumours varies widely between individuals. To date no reliable predictive marker of radiation sensitivity in rectal cancer has been identified. At the cellular level, radiation injury initiates a complex molecular network of DNA damage response (DDR) pathways that leads to cell cycle arrest, attempts at re-constituting the damaged DNA and should this fail, then apoptosis. This review presents the details which suggest the roles of DNA mismatch repair proteins, the lack of which define a distinct subset of colorectal cancers with microsatellite instability (MSI), in the DDR pathways. Hence routine assessment of the MSI status in rectal cancers may potentially serve as a predictor of radiotherapy response, thereby improving patient stratification in the administration of this otherwise toxic treatment.

On biomarkers and pathways in rectal cancer: What's the target?

In spite of tremendous progresses in surgical and chemo-radiotherapeutic regimens, rectal cancer still suffers from high relapse and mortality rates, and metastatic disease is incurable. Here we assess some of the most recent and validated biomarkers and potential targets studied in rectal cancer, and provide comments to a recent monographic topic covering several aspects of colorectal cancer, published in Current Cancer Drug Targets.

Neoadjuvant chemoradiotherapy with or without panitumumab in patients with wild-type KRAS, locally advanced rectal cancer (LARC): a randomized, multicenter, phase II trial SAKK 41/07

BACKGROUND

We conducted a randomized, phase II, multicenter study to evaluate the anti-epidermal growth factor receptor (EGFR) mAb panitumumab (P) in combination with chemoradiotherapy (CRT) with standard-dose capecitabine as neoadjuvant treatment for wild-type KRAS locally advanced rectal cancer (LARC).

PATIENTS AND METHODS

Patients with wild-type KRAS, T3-4 and/or N+ LARC were randomly assigned to receive CRT with or without P (6 mg/kg). The primary end-point was pathological near-complete or complete tumor response (pNC/CR), defined as grade 3 (pNCR) or 4 (pCR) histological regression by Dworak classification (DC).

RESULTS

Forty of 68 patients were randomly assigned to P + CRT and 28 to CRT. pNC/CR was achieved in 21 patients (53%) treated with P + CRT [95% confidence interval (CI) 36%-69%] versus 9 patients (32%) treated with CRT alone (95% CI: 16%-52%). pCR was achieved in 4 (10%) and 5 (18%) patients, and pNCR in 17 (43%) and 4 (14%) patients. In immunohistochemical analysis, most DC 3 cells were not apoptotic. The most common grade ≥3 toxic effects in the P + CRT/CRT arm were diarrhea (10%/6%) and anastomotic leakage (15%/4%).

CONCLUSIONS

The addition of panitumumab to neoadjuvant CRT in patients with KRAS wild-type LARC resulted in a high pNC/CR rate, mostly grade 3 DC. The results of both treatment arms exceeded prespecified thresholds. The addition of panitumumab increased toxicity.

The role of capecitabine in locally advanced rectal cancer treatment: an update

Preoperative infusional 5-fluorouracil (5-FU) and concurrent radiation therapy (RT) followed by total mesorectal surgery is the current standard of care for locally advanced rectal cancer (LAR). When compared with postoperative 5-FU-based chemoradiation, this strategy is associated with significantly lower rates of local relapse, lower toxicity and better compliance. Capecitabine is a rationally designed oral prodrug that is converted into 5-FU by intracellular thymidine phosphorylase. Substitution of infusional 5-FU with capecitabine is an attractive option that provides a more convenient administration schedule and, possibly, increased efficacy. Indeed, incorporation of capecitabine in combined modality neoadjuvant therapy for LAR has been under intense investigation during the last 10 years. Phase I and II clinical trials showed that a regimen consisting of capecitabine 825mg/m(2) twice daily for 7 days/week continuous oral administration in combination with RT is an active and well tolerated regimen, thereby being the preferred concurrent regimen. The definitive demonstration that efficacy of capecitabine/RT is similar to 5-FU/RT has been provided by the NSABP-R-04 and the German Margit trials. One approach to improve outcomes in rectal cancer is to deliver a second RT-sensitizing drug with effective systemic activity. Oxaliplatin and irinotecan are therefore good candidates. However, two phase III trials demonstrated that incorporation of oxaliplatin to capecitabine with RT did not improve early outcomes and, by contrast, increased toxicity. Capecitabine has also been combined with irinotecan. This regimen showed encouraging results in phase I and II clinical trials, which led to an ongoing phase III clinical trial. New strategies with induction chemotherapy with or without chemoradiation prior to surgery are currently under investigation. Whether or not capecitabine has a role in this setting is being investigated in ongoing trials. Incorporation of agents directed towards new targets, such as anti-epidermal growth factor receptor (EGFR) antibodies or antiangiogenic agents, in combination preoperative regimens, is being hampered by results of early trials in which efficacy outcomes with cetuximab were poor and an excessive rate of surgical complications with bevacizumab was observed. The lack of improvements in efficacy with the addition of cetuximab or bevacizumab in the adjuvant treatment of colon cancer led to concerns about further development of these agents in rectal cancer. The role of capecitabine in the postoperative adjuvant setting is the aim of the ongoing Dutch SCRIPT trial. The prediction of response associated with capecitabine has been based on expression of thymidylate synthase and dihydropyrimidine dehydrogenase, as well as on gene expression arrays. All these procedures require further validation and should be considered as investigational. In conclusion, capecitabine can safely and effectively replace intravenous continuous infusion of 5-FU in the preoperative chemoradiation setting for rectal cancer management. The addition of other new antineoplastic agents to a fluoropyrimidine-based regimen remains investigational.

Oncogenic KRAS impairs EGFR antibodies' efficiency by C/EBPβ-dependent suppression of EGFR expression

Oncogenic KRAS mutations in colorectal cancer (CRC) are associated with lack of benefit from epidermal growth factor receptor (EGFR)-directed antibody (Ab) therapy. However, the mechanisms by which constitutively activated KRAS (KRAS(G12V)) impairs effector mechanisms of EGFR-Abs are incompletely understood. Here, we established isogenic cell line models to systematically investigate the impact of KRAS(G12V) on tumor growth in mouse A431 xenograft models as well as on various modes of action triggered by EGFR-Abs in vitro. KRAS(G12V) impaired EGFR-Ab-mediated growth inhibition by stimulating receptor-independent downstream signaling. KRAS(G12V) also rendered tumor cells less responsive to Fc-mediated effector mechanisms of EGFR-Abs-such as complement-dependent cytotoxicity (CDC) and Ab-dependent cell-mediated cytotoxicity (ADCC). Impaired CDC and ADCC activities could be linked to reduced EGFR expression in KRAS-mutated versus wild-type (wt) cells, which was restored by small interfering RNA (siRNA)-mediated knockdown of KRAS4b. Immunohistochemistry experiments also revealed lower EGFR expression in KRAS-mutated versus KRAS-wt harboring CRC samples. Analyses of potential mechanisms by which KRAS(G12V) downregulated EGFR expression demonstrated significantly decreased activity of six distinct transcription factors. Additional experiments suggested the CCAAT/enhancer-binding protein (C/EBP) family to be implicated in the regulation of EGFR promoter activity in KRAS-mutated tumor cells by suppressing EGFR transcription through up-regulation of the inhibitory family member C/EBPβ-LIP. Thus, siRNA-mediated knockdown of C/EBPβ led to enhanced EGFR expression and Ab-mediated cytotoxicity against KRAS-mutated cells. Together, these results demonstrate that KRAS(G12V) signaling induced C/EBPβ-dependent suppression of EGFR expression, thereby impairing Fc-mediated effector mechanisms of EGFR-Abs and rendering KRAS-mutated tumor cells less sensitive to these therapeutic agents.

Multicenter phase II clinical trial of preoperative capecitabine with concurrent radiotherapy in patients with locally advanced rectal cancer

INTRODUCTION

To assess pathologic complete response, sphincter preservation rates and toxicity profile of preoperative chemoradiation with capecitabine in resectable locally advanced rectal cancer.

MATERIALS AND METHODS

Fifty-eight patients from six Spanish centers were included (March 2004 to June 2005) with histological/cytological diagnosis of locally advanced rectal cancer, age between 18 and 80 years, ECOG 0-2, adequate bone marrow, renal and hepatic functions. Prior chemotherapy/radiotherapy was not allowed. Preoperative treatment was capecitabine 825 mg/m(2) bid concomitant to radiotherapy (45 + 5.4 Gy boost over 5.5 weeks). Surgery was performed 4-8 weeks after completion of chemoradiotherapy.

RESULTS

Fifty-eight patients were enrolled in this study: 60.3 % males, median age of 64.5 (30.9-78.7) years, 28.6 % with ECOG 0 and 71.4 % with ECOG 1. Median distance of tumor from the anal verge was 7 (1-12) cm. Fifty-two (89.6. %) patients completed preoperative chemoradiotherapy. Primary tumor and node downstaging occurred in 61.1 and 69.6 % of patients, respectively. Surgery was performed in 55 patients (94.8 %): 80 % had negative lymph nodes and 72.7 % underwent sphincter-preserving procedures. A pathologic complete response was observed in 10.5 % (95 % CI 2.5-18.5) of the patients. Main grade I-II toxicities were leucopenia (43.1 %), neutropenia (24.1 %), anemia (36.2 %), diarrhea (32.8 %) and skin disorders (5.1 %), from which diarrhea (6.9 %), leucopenia (1.7 %) and skin disorders (1.7 %) reached grade III. There were no grade IV toxicities.

CONCLUSIONS

Preoperative capecitabine-based chemoradiation is a well-tolerated and effective neoadjuvant treatment for locally advanced rectal cancer that achieves encouraging rates of tumor downstaging.

Multicenter phase II clinical trial of preoperative capecitabine with concurrent radiotherapy in patients with locally advanced rectal cancer

INTRODUCTION

To assess pathologic complete response, sphincter preservation rates and toxicity profile of preoperative chemoradiation with capecitabine in resectable locally advanced rectal cancer.

MATERIALS AND METHODS

Fifty-eight patients from six Spanish centers were included (March 2004 to June 2005) with histological/cytological diagnosis of locally advanced rectal cancer, age between 18 and 80 years, ECOG 0-2, adequate bone marrow, renal and hepatic functions. Prior chemotherapy/radiotherapy was not allowed. Preoperative treatment was capecitabine 825 mg/m(2) bid concomitant to radiotherapy (45 + 5.4 Gy boost over 5.5 weeks). Surgery was performed 4-8 weeks after completion of chemoradiotherapy.

RESULTS

Fifty-eight patients were enrolled in this study: 60.3 % males, median age of 64.5 (30.9-78.7) years, 28.6 % with ECOG 0 and 71.4 % with ECOG 1. Median distance of tumor from the anal verge was 7 (1-12) cm. Fifty-two (89.6. %) patients completed preoperative chemoradiotherapy. Primary tumor and node downstaging occurred in 61.1 and 69.6 % of patients, respectively. Surgery was performed in 55 patients (94.8 %): 80 % had negative lymph nodes and 72.7 % underwent sphincter-preserving procedures. A pathologic complete response was observed in 10.5 % (95 % CI 2.5-18.5) of the patients. Main grade I-II toxicities were leucopenia (43.1 %), neutropenia (24.1 %), anemia (36.2 %), diarrhea (32.8 %) and skin disorders (5.1 %), from which diarrhea (6.9 %), leucopenia (1.7 %) and skin disorders (1.7 %) reached grade III. There were no grade IV toxicities.

CONCLUSIONS

Preoperative capecitabine-based chemoradiation is a well-tolerated and effective neoadjuvant treatment for locally advanced rectal cancer that achieves encouraging rates of tumor downstaging.

Prediction in rectal cancer

The treatment of rectal cancer largely depends on disease stage at diagnosis, based on which patients can be classified as low, intermediate, or high risk. Prognostic and predictive markers, specific to each risk category, can be applied for optimal risk classification and subsequent treatment allocation. These markers are either histopathological, determined with imaging, or have a biomolecular background. This review provides an overview of the current status of treatment options and the use of prognostic and predictive markers in each risk category. An effort was made to identify those markers that are currently lacking in, but have the potential to improve, the clinical decision process by discussing the data from recent studies aimed at the development of new prognostic and predictive markers. At this moment, none of the markers studied has been proven to be of significant, independent value, justifying implementation in daily clinical practice. However, recent developments in imaging techniques and biomolecular research do show great potential.

KRAS mutation status and clinical outcome of preoperative chemoradiation with cetuximab in locally advanced rectal cancer: a pooled analysis of 2 phase II trials

PURPOSE

Cetuximab-containing chemotherapy is known to be effective for KRAS wild-type metastatic colorectal cancer; however, it is not clear whether cetuximab-based preoperative chemoradiation confers an additional benefit compared with chemoradiation without cetuximab in patients with locally advanced rectal cancer.

METHODS AND MATERIALS

We analyzed EGFR, KRAS, BRAF, and PIK3CA mutation status with direct sequencing and epidermal growth factor receptor (EGFR) and Phosphatase and tensin homolog (PTEN) expression status with immunohistochemistry in tumor samples of 82 patients with locally advanced rectal cancer who were enrolled in the IRIX trial (preoperative chemoradiation with irinotecan and capecitabine; n=44) or the ERBIRIX trial (preoperative chemoradiation with irinotecan and capecitabine plus cetuximab; n=38). Both trials were similarly designed except for the administration of cetuximab; radiation therapy was administered at a dose of 50.4 Gy/28 fractions and irinotecan and capecitabine were given at doses of 40 mg/m2 weekly and 1650 mg/m2/day, respectively, for 5 days per week. In the ERBIRIX trial, cetuximab was additionally given with a loading dose of 400 mg/m2 on 1 week before radiation, and 250 mg/m2 weekly thereafter.

RESULTS

Baseline characteristics before chemoradiation were similar between the 2 trial cohorts. A KRAS mutation in codon 12, 13, and 61 was noted in 15 (34%) patients in the IRIX cohort and 5 (13%) in the ERBIRIX cohort (P=.028). Among 62 KRAS wild-type cancer patients, major pathologic response rate, disease-free survival and pathologic stage did not differ significantly between the 2 cohorts. No mutations were detected in BRAF exon 11 and 15, PIK3CA exon 9 and 20, or EGFR exon 18-24 in any of the 82 patients, and PTEN and EGFR expression were not predictive of clinical outcome.

CONCLUSIONS

In patients with KRAS wild-type locally advanced rectal cancer, the addition of cetuximab to the chemoradiation with irinotecan plus capecitabine regimen was not associated with improved clinical outcome compared with chemoradiation without cetuximab.

The current state of targeted agents in rectal cancer

Targeted biologic agents have an established role in treating metastatic colorectal cancer (CRC), and the integration of targeted therapies into the treatment of CRC has resulted in significant improvements in outcomes. Rapidly growing insight into the molecular biology of CRC, as well as recent developments in gene sequencing and molecular diagnostics, has led to high expectations for the identification of molecular markers to be used in personalized treatment regimens. The mechanisms of action and toxicities of targeted therapies differ from those of traditional cytotoxic chemotherapy. Targeted therapy has raised new insight about the possibility of tailoring treatment to an individual's disease, the assessment of drug effectiveness and toxicity, and the economics of cancer care. This paper covers the last decade of clinical trials that have explored the toxicity and efficacy of targeted agents in locally advanced and metastatic CRC and how their role may benefit patients with rectal cancer. Future efforts should include prospective studies of these agents in biomarker-defined subpopulations, as well as studies of novel agents that target angiogenesis, tumor-stromal interaction, and the cell signaling pathways implicated in rectal cancer.

EGFR/HER-targeted therapeutics in ovarian cancer

Despite decades of research and evolving treatment modalities, survival among patients with epithelial ovarian cancer has improved only incrementally. During this same period, the development of biologically targeted therapeutics has improved survival for patients with diverse malignancies. Many of these new drugs target the human epidermal growth factor receptor (EGFR/HER/ErbB) family of tyrosine kinases, which play a major role in the etiology and progression of many carcinomas, including epithelial ovarian cancer. While several HER-targeted therapeutics are US FDA approved for the treatment of various malignancies, none have gained approval for the treatment of ovarian cancer. Here, we review the published literature on HER-targeted therapeutics for the treatment of ovarian cancer, including novel HER-targeted therapeutics in various stages of clinical development, as well as the challenges that have limited the use of these inhibitors in clinical settings.

Apoptotic proteins as prognostic markers and indicators of radiochemosensitivity in stage II/III rectal cancers

AIM

The expression of pro-apoptotic (Bax) and anti-apoptotic (mutated p53, Bcl-2, Bclxl) proteins was determined retrospectively using immunohistochemistry in pre-treatment biopsy samples from patients with rectal cancer treated with or without preoperative chemoradiation to investigate their role as prognostic markers and indicators of radiochemosensitivity.

METHOD

Biopsy samples from 67 patients operated for stage II/III rectal cancer and enrolled in an active follow-up programme were examined 8-10 years after surgery. Thirty-three had been treated with immediate surgery followed, in selected cases, by adjuvant postoperative chemoradiation. Thirty-four had preoperative chemoradiation. Immunohistochemical staining was carried out using an automated immunostainer on sections of paraffin-embedded tissue.

RESULTS

Independent prognostic factors for rectal cancer death were pN status (hazard ratio 3.82; 95% CI 1.67-8.73) and a high level of Bclxl positivity (hazard ratio 4.75; 95% CI 2.10-10.72) according to multivariate regression analysis by stepwise selection. Bax expression was associated with downstaging and higher survival in irradiated patients (P = 0.0004).

CONCLUSION

Pretreatment evaluation of apoptotic Bax and anti-apoptotic Bclxl factors in biopsy samples of stage II/III rectal cancers may be helpful in selecting tumours that will respond to chemoradiation or in identifying patients who will have limited benefit from chemoradiation and should therefore be selected for a more aggressive systemic regimen.

Locally advanced rectal cancer: a comparison of management strategies

Traditionally, there has been a high local recurrence rate in rectal cancer and 10-40% of patients require a permanent stoma. Both short-course preoperative radiotherapy (SCPRT) and long-course preoperative chemoradiation (CRT) are used to reduce the risk of local recurrence and enable a curative resection. Total mesorectal excision has reduced the rate of local recurrence (even without radiotherapy) to below 10%, but has highlighted a high risk of metastatic disease in 30-40% of patients. Current trials suggest that in resectable cancers, where the preoperative magnetic resonance imaging (MRI) suggests the circumferential resection margin (CRM) is not potentially involved, then SCPRT and CRT are equivalent in terms of outcomes such as local recurrence, disease-free survival (DFS) and overall survival (OS). For patients with more advanced disease, where the CRM is breached or threatened according to the MRI, the integration of more active chemotherapy and biological agents into chemoradiation is an attractive strategy because of the high risk of metastases. However, in none of the trials published in the last decade has chemoradiation impacted on DFS or OS. We examine the strategies of neoadjuvant, concurrent, consolidation (after chemoradiation and before surgery) and postoperative adjuvant chemotherapy with cytotoxic agents, and the integration of biological agents for future potential strategies of treatment. We also compare the trials and compare the different strategies of long-course preoperative radiotherapy and SCPRT; the intensification of preoperative radiation and chemoradiation with dose escalation of external beam radiotherapy, using brachytherapy, intra-operative radiotherapy, hyperfractionation, and various available techniques such as intensity-modulated radiotherapy. We recommend examining dose escalation of radiotherapy to the primary tumour where MRI predicts a threatened CRM. Of the potential treatment strategies involving cytotoxic agents, such as neoadjuvant, concurrent, consolidation and postoperative adjuvant chemotherapy, the most promising would appear to be consolidation chemotherapy following chemoradiation in locally advanced disease, and neoadjuvant chemotherapy in MRI-selected patients who do not require radiation. Improvement in the quality of surgery is also an important future goal.

Neoadjuvant treatment in rectal cancer: actual status

Neoadjuvant (preoperative) concomitant chemoradiotherapy (CRT) has become a standard treatment of locally advanced rectal adenocarcinomas. The clinical stages II (cT3-4, N0, M0) and III (cT1-4, N+, M0) according to International Union Against Cancer (IUCC) are concerned. It can reduce tumor volume and subsequently lead to an increase in complete resections (R0 resections), shows less toxicity, and improves local control rate. The aim of this review is to summarize actual approaches, main problems, and discrepancies in the treatment of locally advanced rectal adenocarcinomas.

Phospho-ERK and AKT status, but not KRAS mutation status, are associated with outcomes in rectal cancer treated with chemoradiotherapy

BACKGROUND

KRAS mutations may predict poor response to radiotherapy. Downstream events from KRAS, such as activation of BRAF, AKT and ERK, may also confer prognostic information but have not been tested in rectal cancer (RC). Our objective was to explore the relationships of KRAS and BRAF mutation status with p-AKT and p-ERK and outcomes in RC.

METHODS

Pre-radiotherapy RC tumor biopsies were evaluated. KRAS and BRAF mutations were assessed by pyrosequencing; p-AKT and p-ERK expression by immunohistochemistry.

RESULTS

Of 70 patients, mean age was 58; 36% stage II, 56% stage III, and 9% stage IV. Responses to neoadjuvant chemoradiotherapy: 64% limited, 19% major, and 17% pathologic complete response. 64% were KRAS WT, 95% were BRAF WT. High p-ERK levels were associated with improved OS but not for p-AKT. High levels of p-AKT and p-ERK expression were associated with better responses. KRAS WT correlated with lower p-AKT expression but not p-ERK expression. No differences in OS, residual disease, or tumor downstaging were detected by KRAS status.

CONCLUSIONS

KRAS mutation was not associated with lesser response to chemoradiotherapy or worse OS. High p-ERK expression was associated with better OS and response. Higher p-AKT expression was correlated with better response but not OS.

Identification of a biomarker profile associated with resistance to neoadjuvant chemoradiation therapy in rectal cancer

OBJECTIVE

To identify a biomarker profile associated with tumor response to chemoradiation (CRT) in locally advanced rectal cancer.

BACKGROUND

Rectal cancer response to neoadjuvant CRT is variable. Whereas some patients have a minimal response, others achieve a pathologic complete response (pCR) and have no viable cancer cells in their surgical specimens. Identifying biomarkers of response will help select patients more likely to benefit from CRT.

METHODS

This study includes 132 patients with locally advanced rectal cancer treated with neoadjuvant CRT followed by surgery. Tumor DNA from pretreatment tumor biopsies and control DNA from paired normal surgical specimens was screened for mutations and polymorphisms in 23 genes. Genetic biomarkers were correlated with tumor response to CRT (pCR vs non-pCR), and the association of single or combined biomarkers with tumor response was determined.

RESULTS

Thirty-three of 132 (25%) patients achieved a pCR and 99 (75%) patients had non-pCR. Three individual markers were associated with non-pCR; v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog mutation (P = 0.0145), cyclin D1 G870A (AA) polymorphism (P = 0.0138), and methylenetetrahydrofolate reductase (NAD(P)H) C677T (TT) polymorphism (P = 0.0120). Analysis of biomarker combinations revealed that none of the 27 patients with both tumor protein p53 (p53) and v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog mutations had a pCR. Further, in patients with both p53 and v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog mutations or the cyclin D1 G870A (AA) polymorphism or the methylenetetrahydrofolate reductase (NAD(P)H) C677T (TT) polymorphism (n = 52) the association with non-pCR was further strengthened; 51 of 52 (98%) of patients were non-pCR. These biomarker combinations had a validity of more than 70% and a positive predictive value of 97% to 100%, predicting that patients harboring these mutation/polymorphism profiles will not achieve a pCR.

CONCLUSIONS

A specific biomarker profile is strongly associated with non-pCR to CRT and could be used to select optimal oncologic therapy in rectal cancer patients. ClinicalTrials.org Identifier: NCT00335816.

Regulation of homeostasis and oncogenesis in the intestinal epithelium by Ras

Much of our current state of knowledge pertaining to the mechanisms controlling intestinal epithelial homeostasis derives from epidemiological, molecular genetic, cell biological, and biochemical studies of signaling pathways that are dysregulated during the process of colorectal tumorigenesis. Activating mutations in members of the RAS oncoprotein family play an important role in the progression of colorectal cancer (CRC) and, by extension, intestinal epithelial homeostasis. Mutations in K-RAS account for 90% of the RAS mutations found in CRC. As such, the study of RAS protein function in the intestinal epithelium is largely encompassed by the study of K-RAS function in CRC. In this review, we summarize the data available from genetically defined in vitro and in vivo models of CRC that aim to characterize the oncogenic properties of mutationally activated K-RAS. These studies paint a complex picture of a multi-functional oncoprotein that engages an array of downstream signaling pathways to influence cellular behaviors that are both pro- and anti-tumorigenic. While the complexity of K-RAS biology has thus far prevented a comprehensive understanding of its oncogenic properties, the work to date lays a foundation for the development of new therapeutic strategies to treat K-RAS mutant CRC.

EGF61 polymorphism predicts complete pathologic response to cetuximab-based chemoradiation independent of KRAS status in locally advanced rectal cancer patients

BACKGROUND

Cetuximab has shown significant clinical activity in metastatic colon cancer. However, cetuximab-containing neoadjuvant chemoradiation has not been shown to improve tumor response in locally advanced rectal cancer patients in recent phase I/II trials. We evaluated functional germline polymorphisms of genes involved in epidermal growth factor receptor pathway, angiogenesis, antibody-dependent cell-mediated cytotoxicity, DNA repair, and drug metabolism, for their potential role as molecular predictors for clinical outcome in locally advanced rectal cancer patients treated with preoperative cetuximab-based chemoradiation.

METHODS

130 patients (74 men and 56 women) with locally advanced rectal cancer (4 with stage II, 109 with stage III, and 15 with stage IV, 2 unknown) who were enrolled in phase I/II clinical trials treated with cetuximab-based chemoradiation in European cancer centers were included. Genomic DNA was extracted from formalin-fixed paraffin-embedded tumor samples and genotyping was done by using PCR-RFLP assays. Fisher's exact test was used to examine associations between polymorphisms and complete pathologic response (pCR) that was determined by a modified Dworak classification system (grade III vs. grade IV: complete response).

RESULTS

Patients with the epidermal growth factor (EGF) 61 G/G genotype had pCR of 45% (5/11), compared with 21% (11/53) in patients heterozygous, and 2% (1/54) in patients homozygous for the A/A allele (P < 0.001). In addition, this association between EGF 61 G allele and pCR remained significant (P = 0.019) in the 59 patients with wild-type KRAS.

CONCLUSION

This study suggested EGF A+61G polymorphism to be a predictive marker for pCR, independent of KRAS mutation status, to cetuximab-based neoadjuvant chemoradiation of patients with locally advanced rectal cancer.

Biomarkers for cetuximab-based neoadjuvant radiochemotherapy in locally advanced rectal cancer

PURPOSE

Phase II trials in locally advanced rectal cancer have shown that cetuximab-based neoadjuvant radiochemotherapy is feasible but without an improvement in complete pathologic response rates. Our goal was to identify patients who would benefit from cetuximab-based neoadjuvant chemoradiation measuring gene expression levels of proteins involved in tumor growth [endothelial growth factor receptor (EGFR)], angiogenesis [VEGF, VEGF receptors 1 and 2 (VEGFR1, VEGFR2)], DNA repair [excision repair cross-complementing 1 (ERCC1)], and drug metabolism [thymidylate synthetase (TS)]. We also determined mutation status of KRAS and BRAF.

EXPERIMENTAL DESIGN

This study was carried out on 130 patients with locally advanced rectal cancer who were enrolled in 4 different phase II clinical trials, using cetuximab-based chemoradiation. Tumor tissues were obtained before neoadjuvant and at surgical therapy. After microdissection, intratumoral gene expression levels and KRAS/BRAF mutation status were analyzed.

RESULTS

A significant decrease of TS, VEGFR1, and VEGFR2 gene expression was seen following neoadjuvant therapy (P < 0.03). High pretreatment VEGF gene expression levels were associated with nonresponse (P = 0.070). KRAS mutations were found in 42% and mutant KRAS (KRAS mt) was significantly associated with pathologic nonresponse (P = 0.037). In patients with wild-type KRAS (KRAS wt), low EGFR was significantly associated with higher nonresponse and VEGF mRNA expressions were associated with complete pathologic response (P = 0.012; P = 0.06). KRAS transversion (KRAS tv) was associated with tumor regression: nonresponse was more common in patients with KRAS tv than with KRAS wt (P = 0.007). BRAF V600E mutations were not detected in any of the patients.

CONCLUSION

This study suggests that pretreatment intratumoral EGFR and VEGF mRNA expression levels as well as KRAS mutation status are predictive markers of pathologic response to neoadjuvant cetuximab-based chemoradiation in locally advanced rectal cancer.

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.

Mutations in K-ras and Epidermal Growth Factor Receptor Expression in Korean Patients With Stages III and IV Colorectal Cancer

K-Ras somatic mutations in advanced colorectal cancer (CRC) can predict resistance to mAbs that target the epidermal growth factor receptor (EGFR). The relationships between K-ras mutations and the EGFR status have not yet been examined, especially in Korean patients. A total of 82 colorectal tumors (stage III-IV) were analyzed. K-Ras mutations at codons 12 and 13 were detected by polymerase chain reaction—single strand conformational polymorphism. The EGFR expressions were examined by immunohistochemistry, and these were graded according to a modified EGFR expression scoring system. The relationships between the patients’ characteristics and the survival time and the gene mutation status were analyzed. The EGFR expression was positive in 69 patients (84.1%) and negative in 13 patients (15.9%). The K-ras mutation rate was 35.4%. In all, 20 (68.9%) cases were mutated at codon 12 and 9 (31.1%) cases were mutated at codon 13. No relationship was observed between the EGFR status and K-ras mutation. The median overall survival (OS) was 68.1 months. There was no difference between the K-ras mutant group and the wild type group for overall survival (30.3% vs 21.0%, respectively, at 36 months, P = .777). K-ras mutation and the EGFR status were not independent prognostic factors for OS ( P = .105 and P = .499, respectively). For the Korean patients with CRC, the rate of an EGFR protein expression was greater than that for the patients in Western countries, and the rate of K-ras mutations was lower than that for patients in Western countries. This study found no correlation between the EGFR status and K-ras mutations in colorectal tumors.

Impact of KRAS Mutations on Management of Colorectal Carcinoma

The epidermal growth factor receptor (EGFR) pathway is a therapeutic target in the management of colorectal cancer (CRC). EGFR antagonists are active in this disease; however, only a subset of patients respond to such therapy. A Kirsten ras sarcoma viral oncogene (KRAS) wild-type (WT) status of the tumor is necessary, but possibly not sufficient, for a response to anti-EGFR monoclonal antibody therapy. Mechanisms of primary resistance to such therapy in patients harboring KRAS WT tumors are discussed. Strategies to overcome resistance to anti-EGFR monoclonal antibody therapy, including novel agents and combinations of novel therapies, are explored. Also, the use of anti-EGFR monoclonal antibodies in the adjuvant and neoadjuvant setting is reviewed.

Adjuvant radiotherapy for rectal cancer: recent results, new questions

Many randomised studies have now well established the role of radiotherapy (RT) in rectal cancer: it decreases the rate of local relapse and improves survival for stage II and III. The benefit of RT remains even in case of total mesorectum excision. Preoperative strategy has a better tolerance and is more efficient than post-operative RT. Two schedules have been widely used: an hypofractionated (5 × 5 Gy) and a normofractionated (45-50 Gy by fractions of 1.8-2 Gy) schedule. Both have advantages and drawbacks. Patients with locally advanced tumours or low-lying cancer must benefit from a protracted schedule, which increases down staging and the number of sphincter-preserving surgery. Combined chemoradiotherapy with 5FU or capecitabine enhances local control without a clear benefit in overall survival or disease-free survival. Adjunction of oxaliplatin does not improve the pathological response rate significantly. Results with cetuximab are still disappointing. Bevacizumab seems to increase widely the radiation response, but more data are needed to confirm these preliminary results. With this modern approach, the rate of local relapse is lower than 10%; the main issue is now the occurrence of distant relapses in 25-30% of the patients. Neo-adjuvant chemotherapy (CT) seems the better way to address this issue, because post-operative CT could be done properly in only 50% of the patients. Large prospective trials using neo-adjuvant CT with or without targeted therapies must be designed taking distant relapses and overall survival as main end-points.

Incorporating fertility preservation into the care of young oncology patients

As the number of cancer survivors continues to increase, oncologists are faced with the challenge of providing cancer therapy to patients who may 1 day want to have children. Yet, gonadotoxic cancer treatments can compromise future fertility, either temporarily or permanently. There are established means of preserving fertility before cancer treatment; specifically, sperm cryopreservation for men and in vitro fertilization and embryo cryopreservation for women. Several innovative techniques are being actively investigated, including oocyte and ovarian follicle cryopreservation, ovarian tissue transplantation, and in vitro follicle maturation, which may expand the number of fertility preservation choices for young cancer patients. Fertility preservation may also require some modification of cancer therapy; thus, patients' wishes regarding future fertility and available fertility preservation alternatives should be discussed before initiation of therapy. This commentary provides an overview of the range of fertility preservation options currently available and under development, using case-based discussions to illustrate ways in which fertility preservation can be incorporated into oncology care. Cases involving breast cancer, testicular cancer, and rectal cancer are described to illustrate fertility issues experienced by male and female patients, as well as to provide examples of strategies for modifying surgical, medical, and radiation therapy to spare fertility. Current guidelines in oncology and reproductive medicine are also reviewed to underscore the importance of communicating fertility preservation options to young patients with cancer.

KRAS and BRAF mutations and PTEN expression do not predict efficacy of cetuximab-based chemoradiotherapy in locally advanced rectal cancer

PURPOSE

Mutations in KRAS and BRAF genes as well as the loss of expression of phosphatase and tensin homolog (PTEN) (deleted on chromosome 10) are associated with impaired activity of antibodies directed against epidermal growth factor receptor in patients with metastatic colorectal cancer. The predictive and prognostic value of the KRAS and BRAF point mutations as well as PTEN expression in patients with locally advanced rectal cancer (LARC) treated with cetuximab-based neoadjuvant chemoradiotherapy is unknown.

METHODS AND MATERIALS

We have conducted phase I and II trials of the combination of weekly administration of cetuximab and irinotecan and daily doses of capecitabine in conjunction with radiotherapy (45 Gy plus 5.4 Gy) in patients with LARC (stage uT3/4 or uN+). The status of KRAS and BRAF mutations was determined with direct sequencing, and PTEN expression status was determined with immunohistochemistry testing of diagnostic tumor biopsies. Tumor regression was evaluated by using standardized regression grading, and disease-free survival (DFS) was calculated according to the Kaplan-Meier method.

RESULTS

A total of 57 patients were available for analyses. A total of 31.6% of patients carried mutations in the KRAS genes. No BRAF mutations were found, while the loss of PTEN expression was observed in 9.6% of patients. Six patients achieved complete remission, and the 3-year DFS rate was 73%. No correlation was seen between tumor regression or DFS rate and a single marker or a combination of all markers.

CONCLUSIONS

In the present series, no BRAF mutation was detected. The presence of KRAS mutations and loss of PTEN expression were not associated with impaired response to cetuximab-based chemoradiotherapy and 3-year DFS.