Cetuximab may inhibit tumor growth and angiogenesis induced by ionizing radiation: a preclinical rationale for maintenance treatment after radiotherapy

Dual effects of radiotherapy on tumor microenvironment and its contribution towards the development of resistance to immunotherapy in gastrointestinal and thoracic cancers

Successful clinical methods for tumor elimination include a combination of surgical resection, radiotherapy, and chemotherapy. Radiotherapy is one of the crucial components of the cancer treatment regimens which allow to extend patient life expectancy. Current cutting-edge radiotherapy research is focused on the identification of methods that should increase cancer cell sensitivity to radiation and activate anti-cancer immunity mechanisms. Radiation treatment activates various cells of the tumor microenvironment (TME) and impacts tumor growth, angiogenesis, and anti-cancer immunity. Radiotherapy was shown to regulate signaling and anti-cancer functions of various TME immune and vasculature cell components, including tumor-associated macrophages, dendritic cells, endothelial cells, cancer-associated fibroblasts (CAFs), natural killers, and other T cell subsets. Dual effects of radiation, including metastasis-promoting effects and activation of oxidative stress, have been detected, suggesting that radiotherapy triggers heterogeneous targets. In this review, we critically discuss the activation of TME and angiogenesis during radiotherapy which is used to strengthen the effects of novel immunotherapy. Intracellular, genetic, and epigenetic mechanisms of signaling and clinical manipulations of immune responses and oxidative stress by radiotherapy are accented. Current findings indicate that radiotherapy should be considered as a supporting instrument for immunotherapy to limit the cancer-promoting effects of TME. To increase cancer-free survival rates, it is recommended to combine personalized radiation therapy methods with TME-targeting drugs, including immune checkpoint inhibitors.

Immunotherapeutics in lung cancers: from mechanistic insight to clinical implications and synergistic perspectives

BACKGROUND

Lung cancer is one of the highly lethal forms of cancer whose incidence has worldwide rapidly increased over the past few decades. About 80-85% of all lung cancer cases constitute non-small cell lung cancer (NSCLC), with adenocarcinoma, squamous cell carcinoma and large cell carcinoma as the main subtypes. Immune checkpoint inhibitors have led to significant advances in the treatment of a variety of solid tumors, significantly improving cancer patient survival rates.

METHODS AND RESULTS

The cytotoxic drugs in combination with anti-PD-(L)1 antibodies is a new method that aims to reduce the activation of immunosuppressive and cancer cell prosurvival responses while also improving direct cancer cell death. The most commonly utilized immune checkpoint inhibitors for patients with non-small cell lung cancer are monoclonal antibodies (Atezolizumab, Cemiplimab, Ipilimumab, Pembrolizumab etc.) against PD-1, PD-L1, and CTLA-4. Among them, Atezolizumab (TECENTRIQ) and Cemiplimab (Libtayo) are engineered monoclonal anti programmed death ligand 1 (PD-L1) antibodies that inhibit binding of PD-L1 to PD-1 and B7.1. As a result, T-cell proliferation and cytokine synthesis are inhibited leading to restoring the immune homeostasis to fight cancer cells.

CONCLUSIONS

In this review article, the path leading to the introduction of immunotherapeutic options in lung cancer treatment is described, with analyzing the benefits and shortages of the current immunotherapeutic drugs. In addition, possibilities to co-administer immunotherapeutic agents with standard cancer treatment modalities are also considered.

Radiation-induced oral mucositis presenting as atypical vascular proliferation: a case report

Radiation-induced oral mucositis is an oral mucosal injury caused by radiation ionizing radiation, which often manifests as oral mucosal congestion, erosion, and ulcers. Radiation-induced oral mucositis manifesting as vascular proliferative changes in the oral mucosa has not been reported. We report a case of oral mucosal atypical vascular proliferation after radiotherapy for a malignant maxillofacial tumor. We discussed the mechanism and treatment of aty-pical vascular proliferation in the oral mucosa secondary to radiotherapy, including diagnosis, treatment, and previous literature.

A systematic review and network meta-analysis of phase III randomised controlled trials for adjuvant therapy following resection of pancreatic ductal adenocarcinoma (PDAC)

BACKGROUND

Several randomised controlled trials (RCTs) have reported various systemic adjuvant therapy regimens following resection of pancreatic ductal adenocarcinoma (PDAC). The most commonly applied include modified FOLFRINOX (mFFX), Gemcitabine/Capecitabine (GemCap) and S1, usually compared to gemcitabine (Gem) alone. However, many of these regimens have not been directly compared in RCTs. This network meta-analysis aims to characterise the impact of adjuvant therapies on overall and disease-free survival in patients having resection of PDAC.

METHODS

A systematic review was conducted using MEDLINE, EMBASE, Cochrane Central and American Society of Clinical Oncology (ASCO) abstracts to identify published phase III RCTs articles up to 9th May 2019 that examined adjuvant systemic therapy in resected pancreatic cancer. Data including study characteristics and outcomes including overall survival (OS) and disease-free survival (DFS) were extracted. Indirect comparisons of all regimens were simultaneously compared using random-effects network meta-analyses (NMA) which maintains randomisation within trials.

RESULTS

Twelve phase III RCTs involving 4947 patients and nine different regimens (5-Flourouracil/Folinic acid (5-FU/FA), Gemcitabine, Gemcitabine/Erlotinib (GemErl), GemCap), mFFX, S1, chemoradiotherapy (CRT), CRT with either 5-FU or Gemcitabine) were identified. S1 was ranked best for overall and disease-free survival followed by mFFX. Whilst there were no significant difference between S1 and mFFX for overall survival (mean difference: 1.6 months, p = 0.8), S1 had significantly longer disease-free survival than mFFX (mean difference: 2.8 months, p < 0.001). Furthermore, S1 was ranked best for lowest overall and haematological grade 3/4 toxicities.

CONCLUSION

This network meta-analysis demonstrates that chemotherapy with S1 or mFFX is superior to GemCap for adjuvant treatment for PDAC, improves survival after surgical resection and should be considered as reasonable standard treatment options in the adjuvant setting and as control arm for future adjuvant clinical trials.

The pro-tumorigenic host response to cancer therapies

Resistance to cancer therapy remains a major challenge in clinical oncology. Although the initial treatment phase is often successful, eventual resistance, characterized by tumour relapse or spread, is discouraging. The majority of studies devoted to investigating the basis of resistance have focused on tumour-related changes that contribute to therapy resistance and tumour aggressiveness. However, over the last decade, the diverse roles of various host cells in promoting therapy resistance have become more appreciated. A growing body of evidence demonstrates that cancer therapy can induce host-mediated local and systemic responses, many of which shift the delicate balance within the tumour microenvironment, ultimately facilitating or supporting tumour progression. In this Review, recent advances in understanding how the host response to different cancer therapies may promote therapy resistance are discussed, with a focus on therapy-induced immunological, angiogenic and metastatic effects. Also summarized is the potential of evaluating the host response to cancer therapy in an era of precision medicine in oncology.

Interdisciplinary multimodality management of stage III nonsmall cell lung cancer

Stage III nonsmall cell lung cancer (NSCLC) comprises about one-third of NSCLC patients and is very heterogeneous with varying and mostly poor prognosis. It is also called "locoregionally or locally advanced disease". Due to its heterogeneity a general schematic management approach is not appropriate. Usually a combination of local therapy (surgery or radiotherapy, depending on functional, technical and oncological operability) with systemic platinum-based doublet chemotherapy and, recently, followed by immune therapy is used. A more aggressive approach of triple agent chemotherapy or two local therapies (surgery and radiotherapy, except for specific indications) has no benefit for overall survival. Until now tumour stage and the general condition of the patient are the most relevant prognostic factors. Characterising the tumour molecularly and immunologically may lead to a more personalised and effective approach. At the moment, after an exact staging and functional evaluation, an interdisciplinary discussion amongst the tumour board is warranted and offers the best management strategy.

Retrospective study comparing anti-EGFR monoclonal antibody plus cisplatin-based chemoradiotherapy versus chemoradiotherapy alone for stage II-IVb nasopharyngeal carcinoma and prognostic value of EGFR and VEGF expression

OBJECTIVES

The benefits of adding anti-EGFR therapy to conventional chemoradiotherapy (CRT) for nasopharyngeal carcinoma (NPC) remain uncertain, possibly because only a subgroup of patients show better outcome. To address this issue, we compared the efficacy of CRT plus cetuximab (CTX) or nimotuzumab (NTZ) to CRT alone for stage II-IVb NPC and examined possible prognostic indicators, including tumour EGFR and VEGR expression levels.

DESIGN, SETTING AND PARTICIPANTS

This retrospective study enrolled 1812 patients at initial NPC diagnosis at Nanfang Hospital Affiliated to Southern Medical University between January 2005 and December 2015. The cetuximab or nimotuzumab plus CRT group (CRT+NTZ/CTX) and the conventional chemoradiotherapy group (CRT) were matched by propensity scoring at 1:5, yielding 282 patients at clinical stage II-IVb with 47 in the CRT+NTZ/CTX group and 235 in the CRT group.

MAIN OUTCOME MEASURES

The endpoints of the present study were locoregional relapse-free survival (LRFS), distant metastasis-free survival (DMFS), overall survival (OS). Immunohistochemistry (IHC) was used to investigate EGFR and VEGF expression levels in 31 patients of the CRT+NTZ/CTX group.

RESULTS

There were no significant differences in LRFS, DMFS and OS, haematologic toxicity reactions, and gastrointestinal reactions between CRT+NTZ/CTX and CRT groups. There was a positive correlation between EGFR and VEGF expression levels. Among CRT+NTZ/CTX patients, those with high EGFR and VEGF expression levels exhibited better DMFS.

CONCLUSIONS

Addition of anti-EGFR to cisplatin-based CRT appears to benefit only a subset of stage II-IVb NPC patients, those with elevated EGFR and VEGF expression levels.

Targeting DNA Double-Strand Break Repair Pathways to Improve Radiotherapy Response

More than half of cancer patients receive radiotherapy as a part of their cancer treatment. DNA double-strand breaks (DSBs) are considered as the most lethal form of DNA damage and a primary cause of cell death and are induced by ionizing radiation (IR) during radiotherapy. Many malignant cells carry multiple genetic and epigenetic aberrations that may interfere with essential DSB repair pathways. Additionally, exposure to IR induces the activation of a multicomponent signal transduction network known as DNA damage response (DDR). DDR initiates cell cycle checkpoints and induces DSB repair in the nucleus by non-homologous end joining (NHEJ) or homologous recombination (HR). The canonical DSB repair pathways function in both normal and tumor cells. Thus, normal-tissue toxicity may limit the targeting of the components of these two pathways as a therapeutic approach in combination with radiotherapy. The DSB repair pathways are also stimulated through cytoplasmic signaling pathways. These signaling cascades are often upregulated in tumor cells harboring mutations or the overexpression of certain cellular oncogenes, e.g., receptor tyrosine kinases, PIK3CA and RAS. Targeting such cytoplasmic signaling pathways seems to be a more specific approach to blocking DSB repair in tumor cells. In this review, a brief overview of cytoplasmic signaling pathways that have been reported to stimulate DSB repair is provided. The state of the art of targeting these pathways will be discussed. A greater understanding of the underlying signaling pathways involved in DSB repair may provide valuable insights that will help to design new strategies to improve treatment outcomes in combination with radiotherapy.

Immunotherapy for the treatment of colorectal tumors: focus on approved and in-clinical-trial monoclonal antibodies

Colorectal cancer is considered a disease of the elderly population. Since the number of geriatric patients continues to rise, monoclonal antibody therapy is the most promising therapy in the recent research. Presently, the monoclonal antibodies most frequently used in the treatment of colorectal tumors are bevacizumab, cetuximab, panitumumab, and ramucirumab. Bevacizumab is a monoclonal antibody that acts on VEGF. Cetuximab and panitumumab act on EGFR. Ramucirumab binds directly to the ligand-binding pocket of VEGFR-2 to block the binding of VEGF-A, VEGF-C, and VEGF-D. These monoclonal antibodies, alone or in association with radiotherapy or chemotherapy, are presenting good results and are increasing patient survival, despite the side effects. Due to the limited number of molecules available, several studies are trying to develop new monoclonal antibodies for the treatment of colorectal tumors. Among those being studied, some recent molecules are in phase I and/or II trials and are yielding advantageous results, such as anti-DR5, anti-Fn14, anti-IGF-1R, anti-EGFR, anti-NRP1, and anti-A33 antibodies. This has been successful in reducing side effects and in treating nonresponsive patients.

Targeted therapies for the treatment of non-small-cell lung cancer: Monoclonal antibodies and biological inhibitors

The usual treatments for patients with non-small-cell lung cancer (NSCLC), such as advanced lung adenocarcinoma, are unspecific and aggressive, and include lung resection, radiotherapy and chemotherapy. Recently, treatment with monoclonal antibodies and biological inhibitors has emerged as an effective alternative, generating effective results with few side effects. In recent years, several clinical trials using monoclonal antibodies presented potential benefits to NSCLC, and 4 of them are already approved for the treatment of NSCLC, such as cetuximab, bevacizumab, nivolumab and pembrolizumab. Also, biological inhibitors are attractive tolls for biological applications. Among the approved inhibitors are crizotinib, erlotinib, afatinib and gefitinib, and side effects are usually mild to intense. Nevertheless, biological molecule treatments are under development, and several new monoclonal antibodies and biological inhibitors are in trial to treat NSCLC. Also under trial study are as follows: anti-epidermal growth factor receptor (EGFR) antibodies (nimotuzumab and ficlatuzumab), anti-IGF 1 receptor (IGF-1R) monoclonal antibody (figitumumab), anti-NR-LU-10 monoclonal antibody (nofetumomab) as well as antibodies directly affecting the cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) molecule (ipilimumab and tremelimumab), to receptor activator of nuclear factor-kappa B ligand (RANKL) (denosumab) or to polymerase enzyme (veliparib and olaparib). Among new inhibitors under investigation are poly-ADP ribose polymerase (PARP) inhibitors (veliparib and olaparib) and phosphatidylinositol 3-kinase (PI3K) inhibitor (buparlisib). However, the success of immunotherapies still requires extensive research and additional controlled trials to evaluate the long-term benefits and side effects.

Dasatinib worsens the effect of cetuximab in combination with fractionated radiotherapy in FaDu- and A431-derived xenografted tumours

Background:

Cetuximab is often combined with radiotherapy in advanced SCCHN. Alternative routes bypassing inhibition of EGFR with cetuximab may overshadow the efficacy of this combination. We undertook this study to investigate a possible role of dasatinib in this scenario.

Methods:

The SCC5, SCC25, SCC29, FaDu and A431 cell lines were assessed in vitro for cell proliferation under cetuximab and dasatinib treatments. In FaDu and A431 cells, dasatinib plus cetuximab resulted in higher proliferation than cetuximab alone. Then, FaDu and A431 cells were implanted into subcutaneous tissue of athymic mice that were irradiated with 30 Gy in 10 fractions over 2 weeks, and treated with cetuximab and dasatinib. Tumour growth, DNA synthesis and angiogenesis were determined. The EGFR, RAS-GTP activity, phosphorylated AKT, ERK1/2, SRC protein levels and VEGF secretion were determined in vitro.

Results:

The addition of dasatinib to cetuximab and radiotherapy increased tumour growth, DNA synthesis and angiogenesis that were associated with RAS, AKT and ERK1/2 activation, and SRC inhibition in FaDu and A431 cells.

Conclusions:

In xenografts derived from these two cell lines, dasatinib did not improve the efficacy of cetuximab combined with radiotherapy. On the contrary, it worsened tumour control achieved by the combination of these two treatments.

Targeted drugs in combination with radiotherapy for the treatment of solid tumors: current state and future developments

The continuously rising use of novel drugs, especially of molecules belonging to the group of targeted drugs is now shaping the therapeutic landscape. However, treatment combinations of targeted drugs with radiotherapy are still rare. Only the monoclonal antibody cetuximab (Erbitux®) has been approved for the treatment of locally advanced squamous cell cancer of the head and neck in combination with radiotherapy. Several targeted compounds are in advanced stages of clinical development for combination treatments with radiotherapy, of which substances with either anti-EGFR or anti-angiogenic mechanisms, such as trastuzumab, panitumumab, erlotinib, cilengitide and bevacizumab are the most promising. Aim of this article is to provide, mainly from a radio-oncological point of view, an overview about the current state as well as to give an outlook on the near future of the most advanced targeted combined treatment concepts for solid tumors.

A phase II study with cetuximab and radiation therapy for patients with surgically resectable esophageal and GE junction carcinomas: Hoosier Oncology Group G05-92

INTRODUCTION

On the basis of the promising activity of cetuximab and radiation therapy for head and neck cancers, we evaluated the efficacy of this regimen followed by surgery in patients with resectable esophageal cancer. This was a phase II, open-label, single-arm, multicenter study of patients with potentially resectable esophageal cancer.

METHODS

Patients received two weekly doses of cetuximab followed by weekly cetuximab combined with radiation therapy for 6 weeks. After a 6- to 8-week rest, patients' primary tumor was resected. The main objective was to evaluate pathologic complete response (pCR) rate in the primary tumor after cetuximab and radiation therapy.

RESULTS

Thirty-nine patients completed the study. Most patients were men (93%), median age was 64 years, performance status was 0 to 1 (95%), patients had a histology of adenocarcinoma (78%), and tumors were located in the esophagus (63%). Grade 3 toxicities in more than 5% of patients included dysphagia (17%), anorexia and dehydration (7%), and dyspnea, fatigue, hypernatremia (5%). Grade 5 aspiration occurred in 2% (1 patient). Four patients died, two from disease progression, one from aspiration pneumonia postsurgery, and one from septic shock. Thirty-one patients (76%) underwent esophagectomy. The pCR rate was 36.6% by intention-to-treat and 48% for patients who underwent esophagectomy. The pCR by histology was 6 of 9 (67%) for squamous cell carcinomas and 9 of 32 (28%) for adenocarcinoma. Earlier-stage disease was associated with increased pCR (IIA 70%, IIB 29%, III 28%).

CONCLUSIONS

Cetuximab and radiation therapy results in a pCR rate that seems at least comparable with that of chemotherapy and radiation therapy. This regimen may be better tolerated than preoperative chemotherapy and radiation therapy in patients with resectable esophageal cancers.

Simvastatin Enhances the Effects of Radiotherapy and Cetuximab on a Cell Line (FaDu) Derived from a Squamous Cell Carcinoma of Head and Neck

Radiotherapy (XRT) delivered with the antibody cetuximab is a standard treatment option for squamous cell carcinomas of head and neck (SCCNH). Cetuximab acts by blocking epidermal growth factor receptor (EGFR) signaling to inhibit cancer progression. However, a significant percentage of patients will not respond to XRT and cetuximab. Statins reduce the synthesis of cholesterol and isoprenoid derivates that may be required for efficient EGFR signaling. We assessed whether the statin simvastatin could improve this combined therapy. In vitro, simvastatin enhanced the effects of XRT alone and in combination with cetuximab in wound healing, cell proliferation, and clonogenic assays in FaDu cells. These results were reflected in xenoimplanted tumors growing into subcutaneous tissue of athymic mice where concomitant treatment with simvastatin decreased tumor growth. Consistently, lower levels of phosphorylated extracellular signal–regulated kinases 1 and 2, phosphatidylinositol 3-kinase/AKT–protein kinase B, and signal transducer and activator of transcription 3 oncoproteins and higher levels of caspase-3 and apoptosis in cell cultures and xenografts were observed. The EGFR-overexpressing A431 cell line was used to reproduce these antitumor effects of simvastatin. Our findings suggest that simvastatin may improve the efficiency of concomitant XRT and cetuximab. Further investigation in the treatment of SCCNH is warranted.

Optimal duration and timing of adjuvant chemotherapy after definitive surgery for ductal adenocarcinoma of the pancreas: ongoing lessons from the ESPAC-3 study

PURPOSE

Adjuvant chemotherapy improves patient survival rates after resection for pancreatic adenocarcinoma, but the optimal duration and time to initiate chemotherapy is unknown.

PATIENTS AND METHODS

Patients with pancreatic ductal adenocarcinoma treated within the international, phase III, European Study Group for Pancreatic Cancer-3 (version 2) study were included if they had been randomly assigned to chemotherapy. Overall survival analysis was performed on an intention-to-treat basis, retaining patients in their randomized groups, and adjusting the overall treatment effect by known prognostic variables as well as the start time of chemotherapy.

RESULTS

There were 985 patients, of whom 486 (49%) received gemcitabine and 499 (51%) received fluorouracil; 675 patients (68%) completed all six cycles of chemotherapy (full course) and 293 patients (30%) completed one to five cycles. Lymph node involvement, resection margins status, tumor differentiation, and completion of therapy were all shown by multivariable Cox regression to be independent survival factors. Overall survival favored patients who completed the full six courses of treatment versus those who did not (hazard ratio [HR], 0.516; 95% CI, 0.443 to 0.601; P < .001). Time to starting chemotherapy did not influence overall survival rates for the full study population (HR, 0.985; 95% CI, 0.956 to 1.015). Chemotherapy start time was an important survival factor only for the subgroup of patients who did not complete therapy, in favor of later treatment (P < .001).

CONCLUSION

Completion of all six cycles of planned adjuvant chemotherapy rather than early initiation was an independent prognostic factor after resection for pancreatic adenocarcinoma. There seems to be no difference in outcome if chemotherapy is delayed up to 12 weeks, thus allowing adequate time for postoperative recovery.

Radiation responses and resistance

The cytotoxic effect of ionizing radiation makes it a popular therapeutic tool against cancer. It is, however, a double-edged sword. Radiation exposure unleashes a plethora of protective and survival mechanisms that include increased proliferation, remodeling of the vasculature and altered cell motility. These mechanisms can play a pro-survival role in remaining cells, contributing to repopulation of tumors after radiation treatment. Understanding these mechanisms and finding ways to minimize their impact would improve the outcome of radiotherapy.

Adjuvant treatments for resected pancreatic adenocarcinoma: a systematic review and network meta-analysis

BACKGROUND

Major adjuvant treatments for pancreatic adenocarcinoma include fluorouracil, gemcitabine, chemoradiation, and chemoradiation plus fluorouracil or gemcitabine. Since the optimum regimen remains inconclusive, we aimed to compare these treatments in terms of overall survival after tumour resection and in terms of grade 3-4 toxic effects with a systematic review and random-effects Bayesian network meta-analysis.

METHODS

We searched PubMed, trial registries, and related reviews and abstracts for randomised controlled trials comparing the above five treatments with each other or observation alone before April 30, 2013. We estimated relative hazard ratios (HRs) for death and relative odds ratios (ORs) for toxic effects among different therapies by combining HRs for death and survival durations and ORs for toxic effects of included trials. We assessed the effects of prognostic factors on survival benefits of adjuvant therapies with meta-regression.

FINDINGS

Ten eligible articles reporting nine trials were included. Compared with observation, the HRs for death were 0·62 (95% credible interval 0·42-0·88) for fluorouracil, 0·68 (0·44-1·07) for gemcitabine, 0·91 (0·55-1·46) for chemoradiation, 0·54 (0·15-1·80) for chemoradiation plus fluorouracil, and 0·44 (0·10-1·81) for chemoradiation plus gemcitabine. The proportion of patients with positive lymph nodes was inversely associated with the survival benefit of adjuvant treatments. After adjustment for this factor, fluorouracil (HR 0·65, 0·49-0·84) and gemcitabine (0·59, 0·41-0·83) improved survival compared with observation, whereas chemoradiation resulted in worse survival than fluorouracil (1·69, 1·12-2·54) or gemcitabine (1·86, 1·04-3·23). Chemoradiation plus gemcitabine was ranked the most toxic, with significantly higher haematological toxic effects than second-ranked chemoradiation plus fluorouracil (OR 13·33, 1·01-169·36).

INTERPRETATION

Chemotherapy with fluorouracil or gemcitabine is the optimum adjuvant treatment for pancreatic adenocarcinoma and reduces mortality after surgery by about a third. Chemoradiation plus chemotherapy is less effective in prolonging survival and is more toxic than chemotherapy.

FUNDING

None.

Adjuvant therapy with cetuximab for locally advanced squamous cell carcinoma of the oropharynx: results from a randomized, phase II prospective trial

BACKGROUND

Cetuximab combined with radiotherapy (RT) is a treatment option for head and neck cancer. The objectives of this randomized, phase II trial were to evaluate the efficacy and safety of cetuximab maintenance therapy following definitive RT with concomitant cetuximab in patients with oropharyngeal cancer.

PATIENTS AND METHODS

Ninety-one patients with stage III-IV M0 oropharyngeal tumors were randomly assigned to the treatment with accelerated concomitant boost RT (69.9 Gy) + cetuximab or the same treatment with the addition of 12 consecutive weeks of cetuximab maintenance therapy. The primary end point was locoregional control (LRC) at 1 year.

RESULTS

LRC at 1 year was superior among patients in the experimental arm, treated with cetuximab maintenance (59% versus 47%). However, LRC was similar between both arms after 2 years of follow-up, as a result of increased locoregional recurrences after the first year in the maintenance group. Patients treated with adjuvant cetuximab do recover very soon from toxic effect after combined treatment.

CONCLUSIONS

Twelve weeks of cetuximab maintenance therapy after concomitant cetuximab + RT in locally advanced oropharyngeal carcinoma is feasible and improves clinical outcomes measured at 1 year. This improvement is not maintained after the second year suggesting that epidermal growth factor receptor blockade is not sufficient to completely eliminate the minimal residual disease.

Development and characterization of an isogenic cell line with a radioresistant phenotype

INTRODUCTION

Radiation resistance is a major cause of death in cancer patients. Cancer cells react during radiotherapy by re-programming specific cell functions that may confer resistance to radiation. The understanding of this complex process is hindered due to the lack of appropriate study models. We describe an experimental development of a radioresistant isogenic cancer cell line, and its molecular characterization.

MATERIALS AND METHODS

A431-cultured cells were irradiated for 7 month until 85 Gy. Then, a selected single cell was left to grow as stable A431-R cell line. Clonogenic assay was used to determine cell survival, the α and β parameters of the LQ model, and the mean inactivation dose. The DNA repair ability of cells was evaluated by pulsed-field electrophoresis method. Differential effect of fractionated radiation was ultimately tested in xenografts. Furthermore, we used a wound healing assay, Western blot for EGFR, AKT and ERK1/2 and ELISA test for vascular endothelial growth factor (VEGF) secretion. Finally we explored CD44 marker and cell cycle distribution.

RESULTS

The established A431-R cell line showed radiation resistance in clonogenic assays, repair of radiation-induced DNA fragmentation and xenografted tumours. The radiation resistance was associated with in vitro higher cell growth and migration, increased levels of former oncoproteins, and secretion of VEGF.

CONCLUSIONS

In this model, the emergence of radiation resistance was associated with the acquisition of biological traits that support more aggressive behaviour of cancer cells. We have generated a model that will be useful for mechanistic studies and development of rational treatments against radiation resistance in cancer.

The impact of cell-cell contact, E-cadherin and EGF receptor on the cellular radiosensitivity of A431 cancer cells

Cell-cell contact is thought to be critically involved in mechanisms leading to radioresistance. Here, we assessed the influence of confluent compared to subconfluent cell culture conditions and the radiosensitizing ability of E-cadherin inhibition alone or in combination with C225-mediated EGFR inhibition in human squamous cell carcinoma cells. Our results show higher radioresistance under subconfluent growth conditions than under confluency. Delayed plating only resulted in higher radiation survival in confluently growing cells. While E-cadherin depletion significantly reduced basal clonogenic survival, increased the rate of apoptosis, and diminished cell adhesion, the cellular radiosensitivity remained unchanged under both subconfluent and confluent conditions. C225 decreased basal cell survival but failed to modify radiation survival. Additional treatment of E-cadherin knockdown cell cultures with C225 did not further reduce basal cell survival or lead to radiosensitization. Interestingly, E-cadherin silencing in 3D cell cultures did not alter radiosensitivity. Our data indicate that cell-cell contact and E-cadherin are not prominently involved in the regulation of radioresistance of human squamous cell carcinoma cells. In addition, no regulatory interaction between E-cadherin and EGFR in the radiation response was observed.

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.

Inhibition of Cathepsin S by Fsn0503 enhances the efficacy of chemotherapy in colorectal carcinomas

Cathepsin S is a lysosomal cysteine protease implicated in tumourigenesis with key roles in invasion and angiogenesis. We have previously shown that the specific inhibition of Cathepsin S using a monoclonal antibody (Fsn0503) blocks colorectal carcinoma tumour growth and angiogenesis in vivo. We investigated whether Cathepsin S expression levels were affected by chemotherapy in human cancer cell lines by RT-PCR. Using colorectal xenograft models, we examined the therapeutic benefit of Cathepsin S inhibition using Fsn0503 in combination with a metronomic dosing regimen of CPT-11. We analysed the effects of the combination therapy on tumour progression and on tumour vascularisation by immunohistochemical staining of tumours. Cathepsin S expression levels are upregulated in HCT116, LoVo, Colo205 cell lines and HUVECs after exposure to CPT-11 in vitro. The administration of Fsn0503 in combination with CPT-11 significantly attenuated tumour growth in comparison to CPT-11 alone in colorectal HCT116 xenograft models. Furthermore, analysis of tumour vascularisation revealed that this was also significantly disrupted by the combination treatment. These results show that the combination of Cathepsin S inhibition with CPT-11 enhances the therapeutic effect of the chemotherapy. This rationale may have clinical application in the treatment of colorectal cancer upon further evaluation.

Combination of pigment epithelium-derived factor with radiotherapy enhances the antitumor effects on nasopharyngeal carcinoma by downregulating vascular endothelial growth factor expression and angiogenesis

Nasopharyngeal carcinoma (NPC), which has the highest incidence in South China, is mainly treated by radiotherapy. However, the survival rate remains low. Angiogenesis is closely correlated with progress of NPC. Thus, the combination of anti-angiogenesis with radiation is an attractive strategy for NPC treatment. A heterogenic xenografted human NPC nude mice model was established to investigate the effect of pigment epithelium-derived factor (PEDF), a potent anti-angiogenic factor, and the combined effect of PEDF and radiotherapy on nasopharyngeal carcinoma. Pigment epithelium- derived factor remarkably suppressed the growth of NPC by 43.52% and decreased the tumor microvessel density (MVD). Pigment epithelium-derived factor had no effects on the proliferation and apoptosis of NPC cell lines by MTT and flow cytometry assay. However, PEDF decreased vascular endothelial growth factor (VEGF) in NPC cell lines by downregulation of hypoxia-inducible factor 1a, a crucial transcriptional factor for VEGF expression, as demonstrated by western blotting and immunofluorescent staining assay. Interestingly, irradiation alone could also effectively downregulate VEGF and MVD of xenografted tumor, which indicates that irradiation suppresses NPC not only by killing tumor cells but also through anti-angiogenesis. Furthermore, combined treatment of PEDF with irradiation enhanced the antitumor efficacy. The MVD and VEGF in the combined therapy were much less than in the treatment with PEDF or radiotherapy alone. Our observation demonstrated that the combination of PEDF with radiotherapy enhances the efficacy of the antitumor effect on NPC by the coordinated inhibition on angiogenesis, which implies the potential role of PEDF as an adjuvant agent for NPC treatment.

The expression of epidermal growth factor receptor and Ki67 in primary and relapse nasopharyngeal cancer: a micro-evidence for anti-EGFR targeted maintenance therapy

Epidermal growth factor receptor (EGFR) was expressed widely in NPC. The aim of this study was to investigate the difference of expression of EGFR and Ki67 in primary and recurrence of NPC to supply a micro-evidence of anti-EGFR targeted maintenance therapy for NPC. A retrospective review of 40 patients with clinical stages I-IV b was performed. Chemoradiation was included chemotherapy with fluorouracil plus cisplatin and irradiation for primary and lymph draining regions. All patients were verified tumor locoregional relapse with/or without distant metastasis by CT or MRI after combined CRT by primary and recurrence biopsies. The correlation between EGFR and Ki67 expression inspected by immunohistochemistry was analyzed. The difference of time to recurrence grouped by different expressions of EGFR and Ki67 was compared by log-rank test. The median follow-up time was 20.0 months ± 2.70 (range 23-71). EGFR and Ki67 expression in primary was not significantly different with recurrent focus. A strong significant correlation between EGFR and Ki67 molecules expression was obtained in primary (r = 0.573; P = 0.001) and in recurrent focus (r = 0.698; P = 0.000). A significantly shorter time to locoregional relapse in patients with positive expression of EGFR than patients with negative EGFR expression in primary (P = 0.010) and in relapse (P = 0.022). There was no significant difference of EGFR and Ki67 expression in primary and recurrence tumor expression. The time to relapse was significantly shorter in high expression of EGFR, which might supply micro-evidence to anti-EGFR targeted maintenance therapy for those patients with EGFR overexpression in primary tumor.

Stem cell property epithelial-to-mesenchymal transition is a core transcriptional network for predicting cetuximab (Erbitux™) efficacy in KRAS wild-type tumor cells

Beyond a well-recognized effect of KRAS mutations in determining de novo inefficacy of cetuximab (CTX) in metastatic colorectal cancer, we urgently need a biomarker signature for predicting CTX efficacy in KRAS wild-type (WT) tumors. CTX-adapted EGFR gene-amplified KRAS WT tumor cell populations were induced by stepwise-chronic exposure of A431 epidermoid cancer cells to CTX. Genome-wide analyses of 44K Agilent's whole human arrays were bioinformatically evaluated by Gene Set Enrichment Analysis (GSEA)-based screening of the KEGG pathway database. Molecular functioning of CTX was found to depend on: (i) The occurrence of a positive feedback loop on Epidermal Growth Factor Receptor (EGFR) activation driven by genes coding for EGFR ligands (e.g., amphiregulin); (ii) the lack of a negative feedback on mitogen-activated protein kinase (MAPK) activation regulated by dual-specificity phosphatases (e.g., DUSP6) and; (iii) the transcriptional status of gene pathways controlling the epithelial-to-mesenchymal transition (EMT) and its reversal (MET) program (actin cytoskeleton and cell-cell communication-e.g., keratins-focal adhesion signaling-e.g., integrins-and EMT-inducing cytokines - e.g., transforming growth factor-β). Quantitative real-time PCR, high-content immunostaining, and flow-cytometry analyses confirmed that CTX efficacy depends on its ability to promote: (i) Stronger cell-cell contacts by up-regulating the expression of the epithelial markers E-cadherin and occludin; (ii) down-regulation of the epithelial transcriptional repressors Zeb, Snail, and Slug accompanied by restoration of cortical F-actin; and (iii) complete prevention of the CD44(pos)/CD24(neg/low) mesenchymal immunophenotype. The impact of EGFR ligands/MAPK phosphatases gene transcripts in predicting CTX efficacy in KRAS WT tumors may be tightly linked with the ability of CTX to concurrently reverse the EMT status, a pivotal property of migrating cancer stem cells.