Neoadjuvant Treatment With Single-Agent Cetuximab Followed by 5-FU, Cetuximab, and Pelvic Radiotherapy: A Phase II Study in Locally Advanced Rectal Cancer

Radiotherapy in the preoperative neoadjuvant treatment of locally advanced rectal cancer

Radiotherapy and chemotherapy are effective treatments for patients with locally advanced rectal cancer (LARC) and can significantly improve the likelihood of R0 resection. Radiotherapy can be used as a local treatment to reduce the size of the tumor, improve the success rate of surgery and reduce the residual cancer cells after surgery. Early chemotherapy can also downgrade the tumor and eliminate micrometastases throughout the body, reducing the risk of recurrence and metastasis. The advent of neoadjuvant concurrent radiotherapy (nCRT) and total neoadjuvant treatment (TNT) has brought substantial clinical benefits to patients with LARC. Even so, given increasing demand for organ preservation and quality of life and the disease becoming increasingly younger in its incidence profile, there is a need to further explore new neoadjuvant treatment options to further improve tumor remission rates and provide other opportunities for patients to choose watch-and-wait (W&W) strategies that avoid surgery. Targeted drugs and immunologic agents (ICIs) have shown good efficacy in patients with advanced rectal cancer but have not been commonly used in neoadjuvant therapy for patients with LARC. In this paper, we review several aspects of neoadjuvant therapy, including radiation therapy and chemotherapy drugs, immune drugs and targeted drugs used in combination with neoadjuvant therapy, with the aim of providing direction and thoughtful perspectives for LARC clinical treatment and research trials.

Changing patterns of neoadjuvant therapy for locally advanced rectal cancer: A narrative review

Standard treatment for patients with locally advanced rectal cancer has been the multidisciplinary approach of neoadjuvant chemoradiotherapy, followed by total mesorectal excision (TME) and postoperative adjuvant chemotherapy. This reduces the local recurrence rate, but the challenge of distant metastasis still persists. The improvement in treatment approach has always been the focus of clinical research and studies have been conducted worldwide in recent years. On one hand, evidence suggests that increasing the intensity of treatment can result in better tumor regression, for example by adding a second drug to the neoadjuvant chemoradiotherapy, or extending the interval between neoadjuvant therapy and surgery, or incorporating chemotherapy and chemoradiotherapy in the neoadjuvant setting. On the other hand, neoadjuvant immunotherapy and selective omission of neoadjuvant radiotherapy may improve the quality of life of patients. In this article, we review the key clinical research progresses in neoadjuvant therapy for locally advanced rectal cancer, hoping to provide some valuable views on the individualized treatment for rectal cancer.

Biologics in rectal cancer

INTRODUCTION

Despite the use of multimodality therapy, locally advanced rectal cancer (LARC) still presents high rates of disease recurrence. Fluoropyrimidine-based chemotherapy concurrently with radiation therapy (RT) remains the cornerstone of neoadjuvant therapy of LARC, and novel therapies are urgently needed in order to improve the clinical outcomes.

AREAS COVERED

We aim to summarize data from completed and ongoing clinical trials addressing the role of biological therapies, including monoclonal antibodies, immune checkpoint inhibitors (ICIs), antibody-drug conjugates, bispecific antibodies, and gene therapies in the systemic therapy of rectal cancer.

EXPERT OPINION

Deeper understanding of the molecular biology of colorectal cancer (CRC) has allowed meaningful advances in the systemic therapy of metastatic disease in the past few years. The larger applicability of biological therapy in CRC, including genome-guided targeted therapy, antiangiogenics, and immunotherapy, gives us optimism for the personalized management of rectal cancer. Microsatellite instability (MSI) tumors have demonstrated high sensitivity to ICIs, and preliminary findings in the neoadjuvant setting of rectal cancer are promising. To date, antiangiogenic and anti-EGFR therapies in LARC have not demonstrated the same benefit seen in metastatic disease. The outstanding results accomplished by biomarker-guided therapy in metastatic CRC will guide future developments of biological therapy in LARC.

Recent advances in (chemo-)radiation therapy for rectal cancer: a comprehensive review

The role of radiation therapy in the treatment of (colo)-rectal cancer has changed dramatically over the past decades. Introduced with the aim of reducing the high rates of local recurrences after conventional surgery, major developments in imaging, surgical technique, systemic therapy and radiation delivery have now created a much more complex environment leading to a more personalized approach. Functional aspects including reduction of acute or late treatment-related side effects, sphincter or even organ-preservation and the unsolved problem of still high distant failure rates have become more important while local recurrence rates can be kept low in the vast majority of patients. This review summarizes the actual role of radiation therapy in different subgroups of patients with rectal cancer, including the current standard approach in different subgroups as well as recent developments focusing on neoadjuvant treatment intensification and/or non-operative treatment approaches aiming at organ-preservation.

Phase I Trial of Trametinib with Neoadjuvant Chemoradiation in Patients with Locally Advanced Rectal Cancer

PURPOSE

The RAS/RAF/MEK/ERK signaling pathway is critical to the development of colorectal cancers, and KRAS, NRAS, and BRAF mutations foster resistance to radiation. We performed a phase I trial to determine the safety of trametinib, a potent MEK1/2 inhibitor, with 5-fluorouracil (5-FU) chemoradiation therapy (CRT) in patients with locally advanced rectal cancer (LARC).

PATIENTS AND METHODS

Patients with stage II/III rectal cancer were enrolled on a phase I study with 3+3 study design, with an expansion cohort of 9 patients at the MTD. Following a 5-day trametinib lead-in, with pre- and posttreatment tumor biopsies, patients received trametinib and CRT, surgery, and adjuvant chemotherapy. Trametinib was given orally daily at 3 dose levels: 0.5 mg, 1 mg, and 2 mg. CRT consisted of infusional 5-FU 225 mg/m2/day and radiation dose of 28 daily fractions of 1.8 Gy (total 50.4 Gy). The primary endpoint was to identify the MTD and recommended phase II dose. IHC staining for phosphorylated ERK (pERK) and genomic profiling was performed on the tumor samples.

RESULTS

Patients were enrolled to all dose levels, and 18 patients were evaluable for toxicities and responses. Treatment was well tolerated, and there was one dose-limiting toxicity of diarrhea, which was attributed to CRT rather than trametinib. At the 2 mg dose level, 25% had pathologic complete response. IHC staining confirmed dose-dependent decrease in pERK with increasing trametinib doses.

CONCLUSIONS

The combination of trametinib with 5-FU CRT is safe and well tolerated, and may warrant additional study in a phase II trial, perhaps in a RAS/RAF-mutant selected population.

Systematic review of treatment intensification using novel agents for chemoradiotherapy in rectal cancer

BACKGROUND

With the well established shift to neoadjuvant treatment for locally advanced rectal cancer, there is increasing focus on the use of radiosensitizers to improve the efficacy and tolerability of radiotherapy. There currently exist few randomized data exploring novel radiosensitizers to improve response and it is unclear what the clinical endpoints of such trials should be.

METHODS

A qualitative systematic review was performed according to the PRISMA guidelines using preset search criteria across the PubMed, Cochrane and Scopus databases from 1990 to 2017. Additional results were generated from the reference lists of included papers.

RESULTS

A total of 123 papers were identified, of which 37 were included; a further 60 articles were obtained from additional referencing to give a total of 97 articles. Neoadjuvant radiosensitization for locally advanced rectal cancer using fluoropyrimidine-based chemotherapy remains the standard of treatment. The oral derivative capecitabine has practical advantages over 5-fluorouracil, with equal efficacy, but the addition of a second chemotherapeutic agent has yet to show a consistent significant efficacy benefit in randomized clinical assessment. Preclinical and early-phase trials are progressing with promising novel agents, such as small molecular inhibitors and nanoparticles.

CONCLUSION

Despite extensive research and promising preclinical studies, a definite further agent in addition to fluoropyrimidines that consistently improves response rate has yet to be found.

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.

Combination Effect of Cetuximab with Radiation in Colorectal Cancer Cells

Aims and background

Colorectal cancer (CRC) is one of the commonest malignant disorders and frequently associated with high expression of epidermal growth factor receptor (EGFR), resulting in advanced disease and a poor prognosis. In this study, we investigated the radiosensitizing effects of the selective EGFR inhibitor cetuximab in human CRC cell lines.

Methods

Four human CRC cell lines, CaCo-2, HCT-8, LoVo, and WiDr, were treated with cetuximab and/or radiation. The effects on cell proliferation and viability were measured by MTT and annexin-V staining, and clonogenic survival assay. The in vivo effect on the growth of CRC xenografts was assessed in athymic nude mice.

Results

Cetuximab in combination with radiation significantly inhibited the in vitro proliferation of CRC cells, with a concomitant increase in cell death, except in WiDr cells. Clonogenic survival assay confirmed that cetuximab worked as a radiosensitizer in three cetuximab-sensitivie CRC cells. However, no correlations were found between the radiosensitivity and EGFR expression level or mutation status of EGFR signaling molecules. In nude mice bearing CRC cell xenografts, cetuximab plus radiation significantly inhibited the tumor growth over either agent alone. Interestingly, the WiDr xenograft was also sensitive to cetuximab and/or radiation in vivo, suggesting host-mediated effects of cetuximab.

Conclusions

Cetuximab enhanced the radiosensitivity of CRC cells in vitro and efficiently inhibited xenograft tumor growth. This study provided a rationale for the clinical application of the selective EGFR inhibitor cetuximab in combination with radiation in CRC. Free full text available at www.tumorionline.it

Prospective randomized trial of neoadjuvant chemotherapy during the 'wait period' following preoperative chemoradiotherapy for rectal cancer: results of the WAIT trial

AIM

The aim was to determine whether the addition of additional cycles of chemotherapy during the 'wait period' following neoadjuvant chemoradiotherapy for rectal cancer improves the pathological complete response (pCR) rate.

METHOD

Rectal cancer patients were randomly allocated either to a standard 10 week wait period before surgery (standard chemoradiotherapy, SCRT) or to receive three cycles of fluorouracil based chemotherapy following chemoradiotherapy during a similar 10 week wait (extended chemoradiotherapy, XCRT). The primary end-point was pCR as determined by blinded pathological assessment.

RESULTS

Forty-nine patients were randomized (SCRTn = 24, XCRTn = 25). pCR occurred in 10 patients overall but there was no significant difference in pCR between the groups (SCRTn = 6, XCRTn = 4, P = 0.49).

CONCLUSION

The addition of three cycles of 5-fluorouracil/leucovorin in a 10 week wait period after conventional chemoradiotherapy seems to result in similar pCR rates in patients with locally advanced rectal cancer based on this small randomized trial.

Phase 2 Neoadjuvant Treatment Intensification Trials in Rectal Cancer: A Systematic Review

PURPOSE

Multiple phase 2 trials of neoadjuvant treatment intensification in locally advanced rectal cancer have reported promising efficacy signals, but these have not translated into improved cancer outcomes in phase 3 trials. Improvements in phase 2 trial design are needed to reduce these false-positive signals. This systematic review evaluated the design of phase 2 trials of neoadjuvant long-course radiation or chemoradiation therapy treatment intensification in locally advanced rectal cancer.

METHODS AND MATERIALS

The PubMed, EMBASE, MEDLINE, and Cochrane Library databases were searched for published phase 2 trials of neoadjuvant treatment intensification from 2004 to 2016. Trial clinical design and outcomes were assessed, with statistical design and compliance rated using a previously published system. Multivariable meta-regression analysis of pathologic complete response (pCR) was conducted.

RESULTS

We identified 92 eligible trials. Patients with American Joint Committee on Cancer stage II and III equivalent disease were eligible in 87 trials (94.6%). In 43 trials (46.7%), local staging on magnetic resonance imaging was mandated. Only 12 trials (13.0%) were randomized, with 8 having a standard-treatment control arm. Just 51 trials (55.4%) described their statistical design, with 21 trials (22.8%) failing to report their sample size derivation. Most trials (n=84, 91.3%) defined a primary endpoint, but 15 different primary endpoints were used. All trials reported pCR rates. Only 38 trials (41.3%) adequately reported trial statistical design and compliance. Meta-analysis revealed a pooled pCR rate of 17.5% (95% confidence interval, 15.7%-19.4%) across treatment arms of neoadjuvant long-course radiation or chemoradiation therapy treatment intensification and substantial heterogeneity among the reported effect sizes (I² = 55.3%, P<.001). Multivariable meta-regression analysis suggested increased pCR rates with higher radiation therapy doses (adjusted P=.025).

CONCLUSIONS

Improvement in the design of future phase 2 rectal cancer trials is urgently required. A significant increase in randomized trials is essential to overcome selection bias and determine novel schedules suitable for phase 3 testing. This systematic review provides key recommendations to guide future treatment intensification trial design in rectal cancer.

The Addition of Target Therapy to Neoadjuvant Chemoradiotherapy in Locally Advanced Rectal Cancer: A Review

Currently, neoadjuvant fluoropyrimidine-based chemoradiotherapy (CRT) is standard practice in the management of locally advanced rectal cancer (LARC). In the last decade there has been a lively interest in the improvement of clinical outcomes by modifying this standard regimen by the addition of further agents. We review combinations of targeted therapies and conventional CRT currently under investigation in LARC patients.

A Dose-finding and Biomarker Evaluation Phase Ib Study of Everolimus in Association With 5-Fluorouracil and Pelvic Radiotherapy as Neoadjuvant Treatment of Locally Advanced Rectal Cancer (E-LARC Study)

BACKGROUND

During the past 20 years, considerable improvement has occurred in the treatment of patients with locally advanced rectal cancer (LARC). With the introduction of multimodal treatment, refinements in preclinical staging and improvements in surgical skills, local relapse is no longer the major problem for patients with LARC. However, many patients die of metastatic disease. The present phase Ib study aimed to establish the maximum tolerated dose of everolimus combined with 5-fluorouracil and radiotherapy in patients with LARC.

PATIENTS AND METHODS

Patients were sequentially assigned to 4 cohorts with an increasing dose of everolimus, starting from 14 days before 5-fluorouracil and radiotherapy and continuing throughout concomitant treatment. The secondary endpoints were the Dworak tumor regression grade, pathologic complete response rate, neoadjuvant rectal score, biomarker assessment (phosphorylated mTOR [mammalian target of rapamycin] protein and phosphorylated-p70S6K protein).

RESULTS

At the time of this report, 12 patients had been treated, and no dose-limiting toxicity was recorded. The most frequently reported acute toxicities were rectal tenesmus, skin rash, diarrhea, and dysuria. All 12 patients underwent curative R0 resection. Two patients had Dworak tumor regression grade 4 (pathologic complete response). No everolimus-related postoperative complications were observed. No relationship was found between biomarker expression and the clinicopathologic outcomes.

CONCLUSION

Although the addition of everolimus did not appear to worsen the toxicity of chemoradiation in patients with LARC, evaluation of its activity deserves further investigation in larger clinical trials.

Pre-operative chemoradiotherapy using capecitabine and cetuximab followed by definitive surgery in patients with operable rectal cancer

BACKGROUND

Achieving a high rate of complete pathological response with pre-operative chemoradiotherapy in rectal cancer is an unmet need. We evaluated the efficacy and toxicity of the combination of cetuximab, capecitabine and radiation therapy in the pre-operative setting of localized rectal cancer.

PATIENTS AND METHODS

Patients with clinically staged T3, T4 or nodepositive rectal cancer were treated with concurrent capecitabine and radiotherapy with weekly cetuximab starting one week before the start of radiation. This was followed by total mesorectal excision within 6-8 weeks. All patients achieving R0 resection received adjuvant capecitabine for 6 cycles.

RESULTS

Fifteen patients were treated and all underwent surgery. Sphincter preservation was achieved in 11 patients (73.3%) and pathological complete response in two. With a median follow up of 48 months (range 8.4-57.5), 12 patients were relapse-free and 14 were alive with 4-year relapse free survival of 80%. Overall survival was 93%. Significant grade 3 and 4 toxicity was mainly cetuximab-induced skin reactions (33%), radiation-induced skin toxicity (13%) and diarrhea (20%).

CONCLUSIONS

Adding cetuximab to pre-operative concurrent capecitabine and radiotherapy provides modest efficacy with manageable toxicity.

Targeted agents in GI radiotherapy: Clinical efficacy and side effects

Approximately 50% of all patients with cancer receive radiotherapy (RT) at some point during their treatment. Despite the advent of modern imaging and advances in planning and delivering highly-conformal and precise RT, further dose escalation to improve clinical outcome is often limited by the potential side-effects to adjacent tissues. Addition of chemotherapy to radiotherapy (CRT) has led to significant clinical improvements in many gastrointestinal malignancies but at the expense of increased toxicity as most chemotherapy drugs lack specificity. Targeted agents modulate specific biological pathways and can potentially enhance RT efficacy. However, so far, the majority of clinical studies incorporating targeted agents into RT and CRT have produced disappointing results in gastrointestinal malignancies. Also, we lack validated biomarkers and methods for monitoring and predicting the efficacy of these agents when combined with RT/CRT. In the present article, we will review the most important targeted therapies, and examine the efficacy and toxicity of these agents when combined with RT/CRT in gastrointestinal malignancies. The shortcomings as well as future challenges and perspectives for the successful use of these compounds with RT/CRT in future trials will also be outlined.

Association of thymidylate synthase polymorphisms with the tumor response to preoperative chemoradiotherapy in rectal cancer: a systematic review and meta-analysis

Preoperative chemoradiotherapy (pCRT) followed by surgery is currently the standard therapy for patients with locally advanced rectal cancer. It is very important to develop biomarkers to prior identify the patients who have a higher likelihood of responding to pCRT. Recently, a series of studies have been conducted to investigate the association of thymidylate synthase (TYMS) polymorphisms with the tumor response to pCRT in rectal cancer, but the results were not consistent and conclusive. In the present study, we performed a systematic literature search for relevant studies up to 30 March 2015 and conducted a meta-analysis to summarize and clarify the association between the TYMS polymorphisms and the tumor response to pCRT in rectal cancer. Finally, 7 studies containing 892 cases for TYMS 2R/3R polymorphism, 7 studies involving 715 cases for TYMS 1494del6 polymorphism and 6 studies containing 616 cases for TYMS 5' untranslated region (UTR) expression allele polymorphism were analyzed in the meta-analysis. The results suggested that TYMS 2R/3R was associated with the response and the patients with 2R/2R or 2R/3R genotype with rectal cancer might benefit more from pCRT than others. On the contrary, neither 1494del6 nor 5'UTR expression allele polymorphisms was associated with the response to pCRT.

The prognostic significance of tumor epidermal growth factor receptor (EGFR) expression change after neoadjuvant chemoradiation in patients with rectal adenocarcinoma

Aim of the study

The aim of this retrospective study was to determine the prognostic impact of epidermal growth factor receptor (EGFR) expression changes during neoadjuvant chemoradiotherapy in patients with locally advanced rectal cancer.

Material and methods

Fifty patients with locally advanced rectal cancer were evaluated. All the patients were administered the total dose of 44 Gy. Capecitabine has been concomitantly administered in the dose 825 mg/m² in two daily oral administrations. Surgery was indicated 4–8 weeks from the chemoradiotherapy completion. Epidermal growth factor receptor expression in the pretreatment biopsies and in the resected specimens was assessed with immunohistochemistry.

Results

All of 50 patients received radiotherapy without interruption up to the total planned dose. In 30 patients sphincter-saving surgery was performed, 20 patients underwent amputation of the rectum. Downstaging was described in 30 patients. Four patients have had complete pathologic remission. Twenty-six patients have had partial remission, the disease was stable in 15 patients. Progression was reported in 5 patients. The median disease-free survival was 64.9 months, median overall survival was 76.4 months. Increased EGFR expression was found in 12 patients (26.1%). A statistically significantly shorter overall survival (p < 0.0001) and disease-free survival (p < 0.0001) was found in patients with increased expression of EGFR compared with patients where no increase in the expression of EGFR during neoadjuvant chemoradiotherapy was observed.

Conclusions

The overexpression of EGFR during neoadjuvant chemoradiotherapy for locally advanced rectal adenokarcinoma associated with significant shorter overall survival and disease free survival.

Does the Addition of Cetuximab to Radiochemotherapy Improve Outcome of Patients with Locally Advanced Rectal Cancer? Long-Term Results from Phase II Trials

Purpose. The addition of cetuximab to radiochemotherapy (RCT) failed to improve complete response rates in locally advanced rectal cancer (LARC). We report the long-term results in patients treated within two sequential clinical trials. Methods. Patients receiving neoadjuvant RCT using capecitabine and irinotecan (CapIri) within a phase I/II trial or CapIri + cetuximab within a phase II trial were evaluated for analysis of disease-free survival (DFS) and overall survival (OS). KRAS exon 2 mutational status had been analyzed in patients receiving cetuximab. Results. 37 patients from the CapIri trial and 49 patients from the CapIri-cetuximab treatment group were evaluable. Median follow-up time was 75.2 months. The 5-year DFS rate was 82% (CapIri) and 79% (CapIri-cetuximab) (P = 0.62). The median OS was 127.4 months. 5-year OS was 73% for both groups (CapIri and CapIri-cetuximab) (P = 0.61). No significant difference in DFS (P = 0.86) or OS (P = 0.39) was noticed between patients receiving CapIri and those receiving CapIri-cetuximab with KRAS wild-type tumors. Conclusions. As the addition of cetuximab did not improve neither DFS nor OS it should not play a role in the perioperative treatment of patients with LARC, not even of patients with (K)RAS WT tumors.

Prospective phase II trial of nimotuzumab in combination with radiotherapy and concurrent capecitabine in locally advanced rectal cancer

PURPOSE

The aim of the study was to evaluate the safety and efficacy of adding concurrent nimotuzumab to preoperative radiotherapy with concurrent capecitabine in locally advanced rectal cancer.

METHODS AND MATERIALS

Patients with rectal cancer (clinical stage T3/4 or N+) were scheduled to receive weekly nimotuzumab (400 mg; days -6, 1, 8, 15, 22, and 29). Capecitabine (825 mg/m(2)) was delivered orally twice daily for the duration of radiotherapy. Radiotherapy was administered at 50.4 Gy (45 + 5.4 Gy). The main endpoint was the pathologic complete response (pCR) rate.

RESULTS

Twenty-one patients with T3 or T4 disease were enrolled; 66.7 % were nodal-positive; the median distance from the anal verge was 5.5 cm. A pCR was achieved in four patients (19.0 %); 71.4 % patients obtained moderate or good tumor regression (Grade 2 and 3). Downstaging occurred in 15/21 (71.4 %) patients by T stage and 11/14 (78.6 %) by N stage. The actual dose intensities (median/mean, %) were nimotuzumab (100, 100) and capecitabine (100, 99.5). The most frequent Grade 1/2 toxicities were radiation dermatitis (57.1 %), nausea/vomiting (52.4 %), leukocytopenia (47.6 %), diarrhea (47.6 %), and proctitis (38.1 %). Grade 3 diarrhea was observed in 9.5 % of patients and Grade 3 leukocytopenia in 4.8 %.

CONCLUSION

These preliminary results indicate that nimotuzumab can be safely combined with radiotherapy plus concurrent capecitabine. The efficacy of this regimen (pCR = 19.0 %) was significantly higher than that observed in previous phase II trials of preoperative radiotherapy with concurrent capecitabine and cetuximab in rectal cancer. Further investigation of concurrent nimotuzumab with radiotherapy plus capecitabine is warranted.

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.

Design and conduct of early-phase radiotherapy trials with targeted therapeutics: lessons from the PRAVO experience

New strategies to facilitate the improvement of physical and integrated biological optimization of high-precision treatment protocols are an important priority for modern radiation oncology. From a clinical perspective, as knowledge accumulates from molecular radiobiology, there is a complex and exciting opportunity to investigate novel approaches to rational patient treatment stratification based on actionable tumor targets, together with the appropriate design of next-generation early-phase radiotherapy trials utilizing targeted therapeutics, to formally evaluate relevant clinical and biomarker endpoints. A unique aspect in the development pathway of systemic agents with presumed radiosensitizing activity will also be the need for special attention on patient eligibility and the rigorous definition of radiation dose-volume relationships and potential dose-limiting toxicities. Based on recent experience from systematically investigating histone deacetylase inhibitors as radiosensitizing agents, from initial studies in preclinical tumor models through the conduct of a phase I clinical study to evaluate tumor activity of the targeted agent as well as patient safety and tumor response to the combined treatment modality, this communication will summarize principles relating to early clinical evaluation of combining radiotherapy and targeted therapeutics.

Epidermal growth factor receptor expression as prognostic marker in patients with anal carcinoma treated with concurrent chemoradiation therapy

PURPOSE

To investigate the prognostic value of epidermal growth factor receptor (EGFR) expression in pretreatment tumor biopsy specimens of patients with anal cancer treated with concurrent 5-fluorouracil and mitomycin C-based chemoradiation therapy (CRT).

METHODS AND MATERIALS

Immunohistochemical staining for EGFR was performed in pretreatment biopsy specimens of 103 patients with anal carcinoma. EGFR expression was correlated with clinical and histopathologic characteristics and with clinical endpoints, including local failure-free survival (LFFS), colostomy-free survival (CFS), distant metastases-free survival (DMFS), cancer-specific survival (CSS), and overall survival (OS).

RESULTS

EGFR staining intensity was absent in 3%, weak in 23%, intermediate in 36% and intense in 38% of the patients. In univariate analysis, the level of EGFR staining was significantly correlated with CSS (absent/weak vs intermediate/intense expression: 5-year CSS, 70% vs 86%, P=.03). As a trend, this was also observed for DMFS (70% vs 86%, P=.06) and LFFS (70% vs 87%, P=.16). In multivariate analysis, N stage, tumor differentiation, and patients' sex were independent prognostic factors for CSS, whereas EGFR expression only reached borderline significance (hazard ratio 2.75; P=.08).

CONCLUSION

Our results suggest that elevated levels of pretreatment EGFR expression could be correlated with favorable clinical outcome in anal cancer patients treated with CRT. Further studies are warranted to elucidate how EGFR is involved in the response to CRT.

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.

Role of radiotherapy for resectable rectal cancer

SUMMARY The role of radiation therapy in the treatment of resectable rectal cancer is better defined than at any point in history; however, as technology improves, increasing treatment options can lead to better patient care when used appropriately with adequate training. Understanding the risk factors for local recurrence can assist in delivering individualized treatment options. Technological improvements such as intensity-modulated radiation therapy have the potential to decrease toxicity, but without adequate training, highly conformal treatment can result in undertreating or missing critical areas. This review will provide an overview of treatment and standard treatment options for resectable rectal cancer, as well as an update on the state of radiation therapy as it relates to rectal cancer and the use of intensity-modulated radiation therapy.

Effect of neoadjuvant cetuximab, capecitabine, and radiotherapy for locally advanced rectal cancer: results of a phase II study

PURPOSE

The aim of this study was to investigate the efficacy and safety of neoadjuvant cetuximab, capecitabine, and radiotherapy for patients with locally advanced rectal cancer.

METHODS

Sixty-three eligible patients were selectively enrolled in this study. Neoadjuvant treatment consisted of cetuximab and capecitabine for 6 weeks and radiotherapy for 5 weeks. Surgical resection was performed 6-8 weeks after the completion of neoadjuvant treatment. KRAS mutation statuses were analyzed retrospectively after the cetuximab treatment. All the patients underwent a standardized postoperative follow-up for at least 3 years.

RESULTS

A pathological complete response (pCR) was achieved in eight patients (12.7 %). Overall down-staging was found in 49 patients (77.8 %). The 3-year disease-free survival (DFS) rate and overall survival (OS) rate was 76.2 % and 81.0 %, respectively. The most common adverse events during neoadjuvant treatment were acneiform skin rash (82.5 %), radiodermatitis (46.0 %), and diarrhea (36.5 %). KRAS mutations were detected in 19 of 63 (31.2 %) tumors. The down-staging rate in patients with KRAS wild-type (WT) was significantly higher than patients with KRAS mutation (P = 0.020). There was no significant difference in the pCR rate, 3-year DFS rate or 3-year OS rate between KRAS WT patients and KRAS-mutated patients.

CONCLUSION

Neoadjuvant treatment with cetuximab and capecitabine-based chemoradiotherapy is safe and well tolerated. The pCR rate, 3-year DFS rate and OS rate are not superior to the rate of neoadjuvant chemoradiotherapy using two or more cytotoxic agents. The KRAS WT is highly associated with tumor down-staging to cetuximab plus capecitabine-based CRT in patients with LARC.

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.

Rectal cancer: state of the art in 2012

PURPOSE OF REVIEW

To discuss the recent developments of multimodal treatment for patients with local advanced rectal cancer, including incorporation of new chemotherapeutic and targeted agents, and the optimal sequence and timing of treatment components.

RECENT FINDINGS

Five randomized trials have been completed to determine whether the addition of oxaliplatin to preoperative, fluorouracil-based chemoradiotherapy (CRT) offers an advantage compared to single-agent fluorouracil CRT. Early results from the ACCORD 12, STAR-01, and NSAPB R-04 trials did not confirm a significant improvement of early efficacy endpoints with the addition of oxaliplatin, whereas the German CAO/ARO/AIO-04 did. Most of the phase II trials incorporating cetuximab into CRT reported disappointingly low rates of pathologic complete response (pCR); the combination of CRT with VEGF inhibition showed encouraging pCR rates; however, it was associated with increased surgical complications. Novel clinical trials address the role of induction chemotherapy, of delayed, minimal or omitted surgery following CRT, or the omission of radiotherapy for selected patients.

SUMMARY

At this time, the use of oxaliplatin or targeted agents as component of multimodality treatment for rectal cancer outside of a clinical trial is not recommended. The inclusion of different treatment options, according to tumor stage, location, imaging features, and response, will render the multimodal treatment approach of rectal cancer more risk-adapted.

[Prognostic significance of changes of tumor epidermal growth factor receptor expression after neoadjuvant chemoradiation in patients with rectal adenocarcinoma]

PURPOSE

The aim of the present study was to examine the effect of neoadjuvant chemoradiation on tumor epidermal growth factor receptor (EGFR) expression in patients with locally advanced rectal adenocarcinoma.

PATIENTS AND METHODS

A total of 53 patients with rectal adenocarcinoma (clinical stages II and III) were studied. Neoadjuvant treatment consisted of 50.4 Gy/28 fractions external radiation with concomitant continuous 5-fluorouracil. Surgical resection was performed 4-6 weeks after the chemoradiation. EGFR expression in the pretreatment biopsies and in the resected specimens was assessed with immunohistochemistry.

RESULTS

Patients with an increase of EGFR expression during chemoradiation had significantly shorter disease-free survival (DFS; p = 0.003) and overall survival (OS; p = 0.005) compared to patients with either no change or decrease in EGFR expression. The 5-year DFS in patients with increased EGFR expression was only 29% compared to 61% in patients without an increase of EGFR expression. Similarly, the 5-year OS of the patients with increased EGFR expression was 29% compared to 66% in patients without an increase of EGFR expression. All recurrences in patients who had an increase of EGFR expression occurred within the first 2 years after the treatment. The increase in EGFR expression was the only significant predictor of DFS (p = 0.007) and OS (p = 0.04) using multivariate Cox regression analysis.

CONCLUSION

An increase of EGFR expression during chemoradiation may be associated with significantly shorter DFS and OS. The increase of EGFR could identify a population of patients in whom the effect of the treatment with anti-EGFR therapy should be studied.

Toward the non-surgical management of locally advanced rectal cancer

Neoadjuvant short-course radiotherapy and long-course chemoradiation (CRT) reduce local recurrence rates when compared to surgery alone and remain widely accepted as standard of care for patients with locally advanced rectal cancer. However, surgery is not without complications and a non-surgical approach in carefully selected patients warrants evaluation. A pathological complete response to CRT is associated with a significant improvement in survival and it has been suggested that a longer time interval between the completion of CRT and surgery increases tumor downstaging. Intensification of neoadjuvant treatment regimens to increase tumor downstaging has been evaluated in a number of clinical trials and more recently the introduction of neoadjuvant chemotherapy prior to CRT has demonstrated high rates of radiological tumor regression. Careful selection of patients using high-resolution MRI may allow a non-surgical approach in a subgroup of patients achieving a complete response to neoadjuvant therapies after an adequate time period. Clearly this needs prospective evaluation within a clinical trial setting, incorporating modern imaging techniques, and tissue biomarkers to allow accurate prediction and assessment of response.

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.

Multicenter randomized phase II clinical trial comparing neoadjuvant oxaliplatin, capecitabine, and preoperative radiotherapy with or without cetuximab followed by total mesorectal excision in patients with high-risk rectal cancer (EXPERT-C)

PURPOSE

To evaluate the addition of cetuximab to neoadjuvant chemotherapy before chemoradiotherapy in high-risk rectal cancer.

PATIENTS AND METHODS

Patients with operable magnetic resonance imaging-defined high-risk rectal cancer received four cycles of capecitabine/oxaliplatin (CAPOX) followed by capecitabine chemoradiotherapy, surgery, and adjuvant CAPOX (four cycles) or the same regimen plus weekly cetuximab (CAPOX+C). The primary end point was complete response (CR; pathologic CR or, in patients not undergoing surgery, radiologic CR) in patients with KRAS/BRAF wild-type tumors. Secondary end points were radiologic response (RR), progression-free survival (PFS), overall survival (OS), and safety in the wild-type and overall populations and a molecular biomarker analysis.

RESULTS

One hundred sixty-five eligible patients were randomly assigned. Ninety (60%) of 149 assessable tumors were KRAS or BRAF wild type (CAPOX, n = 44; CAPOX+C, n = 46), and in these patients, the addition of cetuximab did not improve the primary end point of CR (9% v 11%, respectively; P = 1.0; odds ratio, 1.22) or PFS (hazard ratio [HR], 0.65; P = .363). Cetuximab significantly improved RR (CAPOX v CAPOX+C: after chemotherapy, 51% v 71%, respectively; P = .038; after chemoradiation, 75% v 93%, respectively; P = .028) and OS (HR, 0.27; P = .034). Skin toxicity and diarrhea were more frequent in the CAPOX+C arm.

CONCLUSION

Cetuximab led to a significant increase in RR and OS in patients with KRAS/BRAF wild-type rectal cancer, but the primary end point of improved CR was not met.

Radiotherapy and "new" drugs-new side effects?

BACKGROUND AND PURPOSE

Targeted drugs have augmented the cancer treatment armamentarium. Based on the molecular specificity, it was initially believed that these drugs had significantly less side effects. However, currently it is accepted that all of these agents have their specific side effects. Based on the given multimodal approach, special emphasis has to be placed on putative interactions of conventional cytostatic drugs, targeted agents and other modalities. The interaction of targeted drugs with radiation harbours special risks, since the awareness for interactions and even synergistic toxicities is lacking. At present, only limited is data available regarding combinations of targeted drugs and radiotherapy. This review gives an overview on the current knowledge on such combined treatments.

MATERIALS AND METHODS

Using the following MESH headings and combinations of these terms pubmed database was searched: Radiotherapy AND cetuximab/trastuzumab/panitumumab/nimotuzumab, bevacizumab, sunitinib/sorafenib/lapatinib/gefitinib/erlotinib/sirolimus, thalidomide/lenalidomide as well as erythropoietin. For citation crosscheck the ISI web of science database was used employing the same search terms.

RESULTS

Several classes of targeted substances may be distinguished: Small molecules including kinase inhibitors and specific inhibitors, antibodies, and anti-angiogenic agents. Combination of these agents with radiotherapy may lead to specific toxicities or negatively influence the efficacy of RT. Though there is only little information on the interaction of molecular targeted radiation and radiotherapy in clinical settings, several critical incidents are reported.

CONCLUSIONS

The addition of molecular targeted drugs to conventional radiotherapy outside of approved regimens or clinical trials warrants a careful consideration especially when used in conjunction in hypo-fractionated regimens. Clinical trials are urgently needed in order to address the open question in regard to efficacy, early and late toxicity.

Combination of differentiation and T stage can predict unresponsiveness to neoadjuvant therapy for rectal cancer

AIM

The study aimed to identify the factors predictive for extreme unresponsiveness to neoadjuvant therapy for rectal cancer.

METHOD

Ninety-six patients with rectal cancer received neoadjuvant therapy (41 were treated with radiotherapy and 55 with chemoradiotherapy) before surgery. Tumour response, downstaging, pathological complete response (pCR) and disease-free survival were evaluated.

RESULTS

Tumour response, downstaging and pCR occurred in 70 (72.9%), 47 (49.0%) and 14 (14.6%) patients, respectively. Univariate analyses showed that a large tumour size, T4 stage, elevated serum tumour markers, poor differentiation, radiotherapy alone and mucinous tumour were indicators of poor tumour response and/or downstaging. On multivariate analysis, chemoradiotherapy was found to be predictive for tumour response and downstaging, whereas mucinous type and T4 stage negatively affected tumour response. No variable was found to be associated with pCR, but poor differentiation and T4 stage together predicted extreme unresponsiveness with a high specificity and a high positive predictive value. Very poor disease-free survival was also observed in patients simultaneously carrying these phenotypes.

CONCLUSION

Neoadjuvant chemoradiotherapy is superior to radiotherapy alone in producing a response of rectal cancer. Unresponsiveness was most likely to occur in patients with poor differentiation and T4 disease.

Methylenetetrahydrofolate reductase genetic polymorphisms and toxicity to 5-FU-based chemoradiation in rectal cancer

BACKGROUND

There is a large degree of variation in tumour response and host toxicities associated with neoadjuvant chemoradiation for rectal cancer patients. We performed a complimentary pharmacogenetic study to investigate germline polymorphisms of genes involved in 5-fluorouracil (5-FU) and irinotecan pathways and their potential association with clinical outcomes and toxicities from neoadjuvant chemoradiation in patients with rectal cancer treated in a prospective genotype-directed study.

METHODS

The germline DNA of 131 patients was genotyped for 10 variants in TYMS, MTHFR, DPYD, UGT1A1, ABCC1 and SLCO1B1 genes. Ninety-six patients were treated with 5-FU/radiotherapy (RT) and 35 received 5-FU/RT/irinotecan. Relationships between genetic variants and adverse events, tumour response, overall and disease-free survivals were assessed.

RESULTS

MTHFR 1298A>C and MTHFR diplotypes (for 677C>T and 1298A>C) were associated with chemoradiation-related toxicity when 5-FU was used alone. MTHFR haplotypes (677C-1298C) and diplotypes (CA-TA and TA-TA) showed, respectively, a protective and a negative effect on the incidence of severe diarrhoea or mucositis. No association was observed between genetic markers and drug response.

CONCLUSION

MTHFR polymorphisms can potentially predict toxicity in patients treated with 5-FU as a single chemotherapeutic drug.

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.

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.

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.

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.

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.

Rectal cancer radiotherapy: towards European consensus

BACKGROUND AND PURPOSE

During the first decade of the 21st century several important European randomized studies in rectal cancer have been published. In order to help shape clinical practice based on best scientific evidence, the International Conference on 'Multidisciplinary Rectal Cancer Treatment: Looking for an European Consensus' (EURECA-CC2) was organized. This article summarizes the consensus about imaging and radiotherapy of rectal cancer and gives an update until May 2010.

METHODS

Consensus was achieved using the Delphi method. Eight chapters were identified: epidemiology, diagnostics, pathology, surgery, radiotherapy and chemotherapy, treatment toxicity and quality of life, follow-up, and research questions. Each chapter was subdivided by topic, and a series of statements were developed. Each committee member commented and voted, sentence by sentence three times. Sentences which did not reach agreement after voting round # 2 were openly debated during the Conference in Perugia (Italy) December 2008. The Executive Committee scored percentage consensus based on three categories: "large consensus", "moderate consensus", "minimum consensus".

RESULTS

The total number of the voted sentences was 207. Of the 207, 86% achieved large consensus, 13% achieved moderate consensus, and only three (1%) resulted in minimum consensus. No statement was disagreed by more than 50% of members. All chapters were voted on by at least 75% of the members, and the majority was voted on by >85%. Considerable progress has been made in staging and treatment, including radiation treatment of rectal cancer.

CONCLUSIONS

This Consensus Conference represents an expertise opinion process that may help shape future programs, investigational protocols, and guidelines for staging and treatment of rectal cancer throughout Europe. In spite of substantial progress, many research challenges remain.