Radiation-induced proliferation of the human A431 squamous carcinoma cells is dependent on EGFR tyrosine phosphorylation

Nuclear epidermal growth factor receptor as a therapeutic target

Epidermal growth factor receptor (EGFR) is one of the most well-studied oncogenes with roles in proliferation, growth, metastasis, and therapeutic resistance. This intense study has led to the development of a range of targeted therapeutics including small-molecule tyrosine kinase inhibitors (TKIs), monoclonal antibodies, and nanobodies. These drugs are excellent at blocking the activation and kinase function of wild-type EGFR (wtEGFR) and several common EGFR mutants. These drugs have significantly improved outcomes for patients with cancers including head and neck, glioblastoma, colorectal, and non-small cell lung cancer (NSCLC). However, therapeutic resistance is often seen, resulting from acquired mutations or activation of compensatory signaling pathways. Additionally, these therapies are ineffective in tumors where EGFR is found predominantly in the nucleus, as can be found in triple negative breast cancer (TNBC). In TNBC, EGFR is subjected to alternative trafficking which drives the nuclear localization of the receptor. In the nucleus, EGFR interacts with several proteins to activate transcription, DNA repair, migration, and chemoresistance. Nuclear EGFR (nEGFR) correlates with metastatic disease and worse patient prognosis yet targeting its nuclear localization has proved difficult. This review provides an overview of current EGFR-targeted therapies and novel peptide-based therapies that block nEGFR, as well as their clinical applications and potential for use in oncology.

Management of Oncogene Driven Locally Advanced Unresectable Non-small Cell Lung Cancer

INTRODUCTION

The current standard of care of locally advanced non-small cell lung cancer (LA-NSCLC) is concurrent chemoradiation, followed by consolidation durvalumab. However, there is evidence that the efficacy of chemoradiation and also immunotherapy in many oncogene-positive LA-NSCLC are attenuated, and dependent on the subgroup.

AREAS COVERED

We will firstly review the outcomes of standard-of-care therapy in oncogene-driven LA-NSCLC. We looked at various oncogene driven subgroups and the tumor microenvironment that may explain differential response. Finally, we review the role of targeted therapy in the treatment of LA-NSCLC.

EXPERT OPINION

Each oncogene-positive subgroup should be treated as its own entity, and continued efforts should be undertaken to incorporate targeted therapy, which is likely to yield superior survival outcomes if trial design can be optimized and toxicities can be managed.

Acute radiotherapy-associated oral pain may promote tumor growth at distant sites

Introduction

Patients developing acute radiotherapy induced dermatitis or oral mucositis commonly experience pain. When severe, this radiotherapy-associated pain (RAP) can necessitate treatment breaks; unfortunately, in a variety of cancers, prolongation of the radiotherapy course has been associated with early cancer relapse and/or death. This is often attributed to accelerated repopulation, but it is unknown whether pain or pain signaling constituents might alter tumor behavior and hasten metastatic disease progression. We studied this by testing the hypothesis that severe acute RAP at one site can hasten tumor growth at a distant site.

Methods

Mice underwent single fraction tongue irradiation (27 Gy, or 0 Gy "sham" control) to induce severe glossitis. At the time of maximal oral RAP, one of three luciferase-transfected tumor cell lines were injected via tail vein (4T1, B16F10, MOC2; each paired to their syngeneic host: BALB/c or C57BL/6); tumor burden was assessed via in vivo transthoracic bioluminescence imaging and ex vivo pulmonary nodule quantification. Survival was compared using Kaplan-Meier statistics.

Results

Tongue irradiation and resultant RAP promoted lung tumor growth of 4T1-Luc2 cells in BALB/c mice. This effect was not a result of off-target radiation, nor an artefact of environmental stress caused by standard (subthermoneutral) housing temperatures. RAP did not affect the growth of B16F10-Luc2 cells, however, C57BL/6 mice undergoing tail vein injection of MOC2-Luc2 cells at the time of maximal RAP experienced early lung tumor-attributable death. Lung tumor growth was normalized when RAP was reduced by treatment with resiniferatoxin (300 µg/kg, subcutaneously, once).

Discussion

This research points towards radiation-induced activation of capsaicin-responsive (TRPV1) neurons as the cause for accelerated growth of tumors at distant (unirradiated) sites.

Clinical Radiobiology for Radiation Oncology

This chapter is focused on radiobiological aspects at the molecular, cellular, and tissue level which are relevant for the clinical use of ionizing radiation (IR) in cancer therapy. For radiation oncology, it is critical to find a balance, i.e., the therapeutic window, between the probability of tumor control and the probability of side effects caused by radiation injury to the healthy tissues and organs. An overview is given about modern precision radiotherapy (RT) techniques, which allow optimal sparing of healthy tissues. Biological factors determining the width of the therapeutic window are explained. The role of the six typical radiobiological phenomena determining the response of both malignant and normal tissues in the clinic, the 6R’s, which are Reoxygenation, Redistribution, Repopulation, Repair, Radiosensitivity, and Reactivation of the immune system, is discussed. Information is provided on tumor characteristics, for example, tumor type, growth kinetics, hypoxia, aberrant molecular signaling pathways, cancer stem cells and their impact on the response to RT. The role of the tumor microenvironment and microbiota is described and the effects of radiation on the immune system including the abscopal effect phenomenon are outlined. A summary is given on tumor diagnosis, response prediction via biomarkers, genetics, and radiomics, and ways to selectively enhance the RT response in tumors. Furthermore, we describe acute and late normal tissue reactions following exposure to radiation: cellular aspects, tissue kinetics, latency periods, permanent or transient injury, and histopathology. Details are also given on the differential effect on tumor and late responding healthy tissues following fractionated and low dose rate irradiation as well as the effect of whole-body exposure.

Targeting HER3-dependent activation of nuclear AKT improves radiotherapy of non-small cell lung cancer

BACKGROUND

AKT1 must be present and activated in the nucleus immediately after irradiation to stimulate AKT1-dependent double-strand breaks (DSB) repair through the fast non-homologous end-joining (NHEJ) repair process. We investigated the subcellular distribution of AKT1 and the role of HER family receptor members on the phosphorylation of nuclear AKT and radiation response.

MATERIALS AND METHODS

Using genetic approaches and pharmacological inhibitors, we investigated the subcellular distribution of AKT1 and the role of HER family receptor members on the activation of nuclear AKT in non-small cell lung cancer (NSCLC) cells in vitro. ɤH2AX foci assay was applied to investigate the role of AKT activating signaling pathway on DSB repair. A mouse tumor xenograft model was used to study the impact of discovered signaling pathway activating nuclear AKT on the radiation response of tumors in vivo.

RESULTS

Our data suggests that neither ionizing radiation (IR) nor stimulation with HER family receptor ligands induced rapid nuclear translocation of endogenous AKT1. GFP-tagged exogenous AKT1 translocated to the nucleus under un-irradiated conditions and IR did not stimulate this translocation. Nuclear translocation of GFP-AKT1 was impaired by the AKT inhibitor MK2206 as shown by its accumulation in the cytoplasmic fraction. IR-induced phosphorylation of nuclear AKT was primarily dependent on HER3 expression and tyrosine kinase activation of epidermal growth factor receptor. In line with the role of AKT1 in DSB repair, the HER3 neutralizing antibody patritumab as well as HER3-siRNA diminished DSB repair in vitro. Combination of patritumab with radiotherapy improved the effect of radiotherapy on tumor growth delay in a xenograft model.

CONCLUSION

IR-induced activation of nuclear AKT occurs inside the nucleus that is mainly dependent on HER3 expression in NSCLC. These findings suggest that targeting HER3 in combination with radiotherapy may provide a logical treatment option for investigation in selected NSCLC patients.

Ablative Radiotherapy as a Strategy to Overcome TKI Resistance in EGFR-Mutated NSCLC

Simple Summary

Most patients with EGFR-mutated NSCLC who receive treatment with targeted therapy will eventually develop resistance, meaning the therapy will lose its efficacy. Prior studies have shown a benefit to continuing to treat patients on TKI therapy despite limited progression of one or more sites of metastatic disease in EGFR-mutated NSCLC. Based on the data reviewed here, the use of radiation therapy to sites of disease progression is both efficacious and carries a low risk for side effects, with the added benefit of allowing patients to continue on TKI therapy.

Abstract

Tyrosine kinase inhibitor (TKI) therapy is the recommended first-line treatment for metastatic non-small-cell lung cancer (NSCLC) positive for epidermal growth factor receptor (EGFR) gene mutation. However, most individuals treated with TKI therapy for EGFR-mutant NSCLC will develop tumor resistance to TKI therapy. Therapeutic strategies to overcome TKI resistance are the topic of several ongoing clinical trials. One potential strategy, which has been explored in numerous trials, is the treatment of progressive sites of disease with stereotactic body radiation treatment (SBRT) or stereotactic radiosurgery (SRS). We sought to review the literature pertaining to the use of local ablative radiation therapy in the setting of acquired resistance to TKI therapy and to discuss stereotactic radiation therapy as a strategy to overcome TKI resistance.

Radiotherapy-induced metabolic hallmarks in the tumor microenvironment

Radiation is frequently administered for cancer treatment, but resistance or remission remains common. Cancer cells alter their metabolism after radiotherapy to reduce its cytotoxic effects. The influence of altered cancer metabolism extends to the tumor microenvironment (TME), where components of the TME exchange metabolites to support tumor growth. Combining radiotherapy with metabolic targets in the TME can improve therapy response. We review the metabolic rewiring of cancer cells following radiotherapy and put these observations in the context of the TME to describe the metabolic hallmarks of radiotherapy in the TME.

Extracellular acidosis stimulates breast cancer cell motility through aryl hydrocarbon receptor and c-Src kinase activation

A reduction in extracellular pH (pHe) is a characteristic of most malignant tumors. The aryl hydrocarbon receptor (AhR) is a transcription factor localized in a cytosolic complex with c-Src, which allows it to trigger non-genomic effects through c-Src. Considering that the slightly acidic tumor microenvironment promotes breast cancer progression in a similar way to the AhR/c-Src axis, our aim was to evaluate whether this pathway could be activated by low pHe. We examined the effect of pHe 6.5 on AhR/c-Src axis using two breast cancer cell lines (MDA-MB-231 and LM3) and mammary epithelial cells (NMuMG) and found that acidosis increased c-Src phosphorylation only in tumor cells. Moreover, the presence of AhR inhibitors prevented c-Src activation. Low pHe reduced intracellular pH (pHi), while amiloride treatment, which is known to reduce pHi, induced c-Src phosphorylation through AhR. Analyses were conducted on cell migration and metalloproteases (MMP)-2 and -9 activities, with results showing an acidosis-induced increase in MDA-MB-231 and LM3 cell migration and MMP-9 activity, but no changes in NMuMG cells. Moreover, all these effects were blocked by AhR and c-Src inhibitors. In conclusion, acidosis stimulates the AhR/c-Src axis only in breast cancer cells, increasing cell migration and MMP-9 activity. Although the AhR activation mechanism still remains elusive, a reduction in pHi may be thought to be involved. These findings suggest a critical role for the AhR/c-Src axis in breast tumor progression stimulated by an acidic microenvironment. This article is protected by copyright. All rights reserved.

In vitro Study of Radiosensitivity Effects of Galbanic Acid on Ovarian Tumor Cells (OVCAR-3 Cell Line)

Background and aims: Radiotherapy ranks among the most important procedures in ovarian cancer therapy. However, radioresistance is becoming more prevalent and is one of the main causes of poor clinical outcomes. To overcome this problem, radiosensitizers may be used. The present study aimed to evaluate the radiosensitizing properties of galbanic acid (GBA) on ovarian cancer cells in vitro. Materials and methods: OVCAR-3 cells, an ovarian cancer cell line, were treated with increasing concentrations of GBA (5, 10, 20, and 40 μg/mL) for 24, 48, and 72 h to determine its half-maximal inhibitory concentration (IC50). Cell viability was assessed by alamar Blue assay. The cells treated with 10 μg/mL GBA for 24 h were exposed to increasing doses of radiation (1, 2, and 4 Gy) and the survival fraction was investigated by clonogenic assay. Results: Assessment of cell viability indicated that GBA caused toxicity in a dose-dependent manner. Additionally, GBA pretreatment significantly improved the radiosensitivity of the cells, and survival fraction data indicated synergy between GBA and radiation. Conclusion: Taken together, the current findings highlight GBA as a potent radiosensitizing agent; however, further research is required to determine the molecular mechanisms of the observed effect both in vitro and in vivo. It is also suggested that the radiosensitization effect of GBA on other cell types should be studied in the future.

Targeted therapy moves to earlier stages of non-small-cell lung cancer: emerging evidence, controversies and future challenges

Lung cancer continues to be the leading cause of cancer mortality and a serious health problem despite the numerous advances made in the last decade and the rapid advance of research in this field. In recent years, there has been a decrease in mortality from lung cancer coinciding with the approval times of targeted therapy. To date, targeted therapy has been used in the context of advanced disease in clinical practice, with great benefits in survival and quality of life. The next step will be to incorporate targeted therapy into the treatment of earlier stages of non-small-cell lung cancer, and there is already a randomized trial showing a disease-free survival benefit. However, there are many questions that need to be resolved first. In the present review, the authors discuss the findings of published reports and ongoing clinical trials assessing the role of targeted therapies in nonmetastatic disease.

Combining radiotherapy with targeted therapies in non-small cell lung cancer: focus on anti-EGFR, anti-ALK and anti-angiogenic agents

The combination of radiotherapy (RT) with targeted agents in non-small cell lung cancer (NSCLC) has been expected to improve the therapeutic ratio and tumor control. The EGFR blockade enhances the antitumor effect of RT. The ALK inhibition elicits anti-proliferative, pro-apoptotic and antiangiogenic effects in ALK-positive NSCLC cell lines, enhanced by the exposure to RT. The antiangiogenic agents normalize pathological tumor vessels, thus decrease tumor cell hypoxia and improve radiosensitivity. To date, however, none of the targeted agents combined with RT has shown proven clinical benefit over standard chemoradiation (CRT) in locally advanced NSCLC. The risk of potential excessive toxicity related to the therapeutic combination of RT and targeted agents cannot be ignored. Well-designed clinical trials may allow development of more effective combination strategies. Another potential application of combined RT and targeted therapies in oncogene-driven NSCLC is metastatic oligoprogressive or oligopersistent disease. The use of RT in oligoprogressive oncogene-driven NSCLC, while continuing first line targeted therapy, can potentially eradicate resistant cell clones and provide survival benefit. Likewise, the consolidation of oligopersistent foci (molecularly resistant to first line targeted therapy) may potentially interfere with the natural course of the disease by avoiding or delaying progression. We discuss here the molecular and radiobiological mechanisms of combining RT and targeted agents, and summarize current clinical experience.

ceRNA Networks: The Backbone Role in Neoadjuvant Chemoradiotherapy Resistance/Sensitivity of Locally Advanced Rectal Cancer

Approximately 40% of rectal cancers during initial diagnosis are identified as locally advanced rectal cancers (LARCs), for which the standardized treatment scenario is total mesorectal excision following neoadjuvant chemoradiotherapy (nCRT). nCRT can lead to discernible reductions in local relapse rate and distant metastasis rate in LARC patients, in whom previously inoperable tumors may potentially be surgically removed. However, only 4% to 20% cases can attain pathological complete response, and the remaining patients who are unresponsive to nCRT have to suffer from the side effects plus toxicities and may encounter poor survival outcomes due to the late surgical intervention. As such, employing potential biomarkers to differentiate responders from nonresponders before nCRT implementation appears to be the overarching goal. Well-defined competing endogenous RNA (ceRNA) networks include long noncoding RNA (lncRNA)-microRNA (miRNA)-mRNA and circRNA-miRNA-mRNA networks. As ceRNAs, lncRNAs, and circRNAs sponge miRNAs to indirectly suppress miRNAs downstream of oncogenic mRNAs or tumor-suppressive mRNAs. The abnormal expression of mRNAs regulates the nCRT-induced DNA damage repair process through pluralistic carcinogenic signaling pathways, thereby bringing about alterations in the nCRT resistance/sensitivity of tumors. Moreover, many molecular mechanisms relevant to cell proliferation, metastasis, or apoptosis of cancers (eg, epithelial-mesenchymal transition and caspase-9-caspase-3 pathway) are influenced by ceRNA networks. Herein, we reviewed a large group of abnormally expressed mRNAs and noncoding RNAs that are associated with nCRT resistance/sensitivity in LARC patients and ultimately pinpointed the backbone role of ceRNA networks in the molecular mechanisms of nCRT resistance/sensitivity.

Phase 2 Study of Nimotuzumab in Combination With Concurrent Chemoradiotherapy in Patients With Locally Advanced Non-Small-Cell Lung Cancer

BACKGROUND

We evaluated the tolerability and efficacy of nimotuzumab, a humanized IgG1 monoclonal anti-epidermal growth factor receptor antibody, with concurrent chemoradiotherapy in patients with unresectable locally advanced non-small-cell lung cancer.

PATIENTS AND METHODS

In this multicenter, single-arm, open-label, phase 2 trial conducted in Japan (JapicCTI-090825), patients received thoracic radiotherapy (60 Gy, 2 Gy per fraction, 6 weeks) and four 4-week cycles of chemotherapy (day 1, cisplatin 80 mg/m²; days 1 and 8, vinorelbine 20 mg/m²). Nimotuzumab 200 mg was administrated weekly for 16 weeks. The primary endpoint was treatment completion rate, defined as the percentage of patients completing 60 Gy of radiotherapy within 8 weeks, 2 cycles of chemotherapy, and at least 75% of the required nimotuzumab dose during the initial 2-cycle concurrent chemoradiotherapy period.

RESULTS

Of 40 patients enrolled, 39 received the study treatment, which was well tolerated, with a completion rate of 87.2%. Thirty-eight patients completed 60 Gy of radiotherapy within 8 weeks. Infusion reaction, grade 3 or higher rash, grade 3 or higher radiation pneumonitis, or grade 4 or higher nonhematologic toxicity were not observed. The objective response rate was 69.2%. The median progression-free survival (PFS) and 5-year PFS rate were 508 days and 29.0%, respectively. The 5-year PFS rate in patients with non-squamous cell carcinoma (n = 23) was 13.7% and in patients with squamous cell carcinoma (n = 16) was 50.0%. The 5-year overall survival rate was 58.4%.

CONCLUSION

Addition of nimotuzumab to the concurrent chemoradiotherapy regimen was well tolerated and showed potential for treating patients with locally advanced non-small-cell lung cancer, particularly squamous cell carcinoma.

Comparative Analysis of the Development of Acquired Radioresistance in Canine and Human Mammary Cancer Cell Lines

Research using in vitro canine mammary cancer cell lines and naturally-occurring canine mammary tumors are not only fundamental models used to advance the understanding of cancer in veterinary patients, but are also regarded as excellent translational models of human breast cancer. Human breast cancer is commonly treated with radiotherapy; however, tumor response depends on both innate radiosensitivity and on tumor repopulation by cells that develop radioresistance. Comparative canine and human studies investigating the mechanisms of radioresistance may lead to novel cancer treatments that benefit both species. In this study, we developed a canine mammary cancer (REM-134) radioresistant (RR) cell line and investigated the cellular mechanisms related to the development of acquired radioresistance. We performed a comparative analysis of this resistant model with our previously developed human breast cancer radioresistant cell lines (MCF-7 RR, ZR-751 RR, and MDA-MB-231 RR), characterizing inherent differences through genetic, molecular, and cell biology approaches. RR cells demonstrated enhanced invasion/migration capabilities, with phenotypic evidence suggestive of epithelial-to-mesenchymal transition. Similarities were identified between the REM-134 RR, MCF-7 RR, and ZR-751 RR cell lines in relation to the pattern of expression of both epithelial and mesenchymal genes, in addition to WNT, PI3K, and MAPK pathway activation. Following the development of radioresistance, transcriptomic data indicated that parental MCF-7 and ZR-751 cell lines changed from a luminal A classification to basal/HER2-overexpressing (MCF-7 RR) and normal-like/HER2-overexpressing (ZR-751 RR). These radioresistant subtypes were similar to the REM-134 and REM-134 RR cell lines, which were classified as HER2-overexpressing. To our knowledge, our study is the first to generate a canine mammary cancer RR cell line model and provide a comparative genetic and phenotypic analysis of the mechanisms of acquired radioresistance between canine and human cancer cell lines. We demonstrate that the cellular processes that occur with the development of acquired radioresistance are similar between the human and canine cell lines; our results therefore suggest that the canine model is appropriate to study both human and canine radioresistant mammary cancers, and that treatment strategies used in human medicine may also be applicable to veterinary patients.

Radiation resistance in head and neck squamous cell carcinoma: dire need for an appropriate sensitizer

Radiation is a significant treatment for patients with head and neck cancer. Despite advances to improve treatment, many tumors acquire radiation resistance resulting in poor survival. Radiation kills cancer cells by inducing DNA double-strand breaks. Therefore, radiation resistance is enhanced by efficient repair of damaged DNA. Head and neck cancers overexpress EGFR and have a high frequency of p53 mutations, both of which enhance DNA repair. This review discusses the clinical criteria for radiation resistance in patients with head and neck cancer and summarizes how cancer cells evade radiation-mediated apoptosis by p53- and epidermal growth factor receptor (EGFR)-mediated DNA repair. In addition, we explore the role of cancer stem cells in promoting radiation resistance, and how the abscopal effect provides rationale for combination strategies with immunotherapy.

Combination Therapy With Charged Particles and Molecular Targeting: A Promising Avenue to Overcome Radioresistance

Radiotherapy plays a central role in the treatment of cancer patients. Over the past decades, remarkable technological progress has been made in the field of conventional radiotherapy. In addition, the use of charged particles (e.g., protons and carbon ions) makes it possible to further improve dose deposition to the tumor, while sparing the surrounding healthy tissues. Despite these improvements, radioresistance and tumor recurrence are still observed. Although the mechanisms underlying resistance to conventional radiotherapy are well-studied, scientific evidence on the impact of charged particle therapy on cancer cell radioresistance is restricted. The purpose of this review is to discuss the potential role that charged particles could play to overcome radioresistance. This review will focus on hypoxia, cancer stem cells, and specific signaling pathways of EGFR, NFκB, and Hedgehog as well as DNA damage signaling involving PARP, as mechanisms of radioresistance for which pharmacological targets have been identified. Finally, new lines of future research will be proposed, with a focus on novel molecular inhibitors that could be used in combination with charged particle therapy as a novel treatment option for radioresistant tumors.

Inhibition of FGFR2-Signaling Attenuates a Homology-Mediated DNA Repair in GIST and Sensitizes Them to DNA-Topoisomerase II Inhibitors

Deregulation of receptor tyrosine kinase (RTK)-signaling is frequently observed in many human malignancies, making activated RTKs the promising therapeutic targets. In particular, activated RTK-signaling has a strong impact on tumor resistance to various DNA damaging agents, e.g., ionizing radiation and chemotherapeutic drugs. We showed recently that fibroblast growth factor receptor (FGFR)-signaling might be hyperactivated in imatinib (IM)-resistant gastrointestinal stromal tumors (GIST) and inhibition of this pathway sensitized tumor cells to the low doses of chemotherapeutic agents, such as topoisomerase II inhibitors. Here, we report that inhibition of FGFR-signaling in GISTs attenuates the repair of DNA double-strand breaks (DSBs), which was evidenced by the delay in γ-H2AX decline after doxorubicin (Dox)-induced DNA damage. A single-cell gel electrophoresis (Comet assay) data showed an increase of tail moment in Dox-treated GIST cells cultured in presence of BGJ398, a selective FGFR1-4 inhibitor, thereby revealing the attenuated DNA repair. By utilizing GFP-based reporter constructs to assess the efficiency of DSBs repair via homologous recombination (HR) and non-homologous end-joining (NHEJ), we found for the first time that FGFR inhibition in GISTs attenuated the homology-mediated DNA repair. Of note, FGFR inhibition/depletion did not reduce the number of BrdU and phospho-RPA foci in Dox-treated cells, suggesting that inhibition of FGFR-signaling has no impact on the processing of DSBs. In contrast, the number of Dox-induced Rad51 foci were decreased when FGFR2-mediated signaling was interrupted/inhibited by siRNA FGFR2 or BGJ398. Moreover, Rad51 and -H2AX foci were mislocalized in FGFR-inhibited GIST and the amount of Rad51 was substantially decreased in -H2AX-immunoprecipitated complexes, thereby illustrating the defect of Rad51 recombinase loading to the Dox-induced DSBs. Finally, as a result of the impaired homology-mediated DNA repair, the increased numbers of hypodiploid (i.e., apoptotic) cells were observed in FGFR2-inhibited GISTs after Dox treatment. Collectively, our data illustrates for the first time that inhibition of FGF-signaling in IM-resistant GIST interferes with the efficiency of DDR signaling and attenuates the homology-mediated DNA repair, thus providing the molecular mechanism of GIST’s sensitization to DNA damaging agents, e.g., DNA-topoisomerase II inhibitors.

Retracted Article: Down-regulation of the radiation-induced pEGFRThr654 mediated activation of DNA-PK by Cetuximab in cervical cancer cells

The phosphorylation of EGFR^Thr654 is required for nuclear EGFR importing, and our previous study has shown that pEGFR^Thr654 is an independent prognostic factor for the low survival rate of patients with cervical squamous carcinoma. Now, we aim to examine the role of pEGFR^Thr654 in the activation of DNA-PK and radio resistance. Either CaSki or HeLa cells were exposed to a dose of 4 Gy with a 6 MV X-ray in the presence or absence of Cetuximab or Gefitinib, then EGFR, pEGFR^Thr654, DNA-PKcs and pDNA-PK^Thr2609 levels were determined using a western blot. DNA damage was quantified with γH2AX foci analysis and the response of CaSki and HeLa cells to irradiation was determined using a colony formation assay. In CaSki and HeLa cells, irradiation induced nuclear EGFR accumulation, and pEGFR^Thr654 and pDNA-PK^Thr2609 levels were both significantly increased. Cetuximab pre-treatment significantly reduced the expression of pEGFR^Thr654 and pDNA-PK^Thr2609 and enhanced the γH2AX foci per cell and sensitivity enhancement ratio in CaSki cells. Gefitinib pre-treatment had a similar but weaker effect. In HeLa cells, similar effects of Cetuximab and Gefitinib on pEGFR^Thr654 and pDNA-PK^Thr2609 were observed, and no significant difference was found. We found that Cetuximab had a better effect than Gefitinib on attenuating the radio resistance in cervical squamous carcinoma cells via inhibiting pEGFR^Thr654-mediated nuclear EGFR transport and related DNA-PK^T2609-mediated DNA repair. However, in adenocarcinoma cells, both EGFR-targeted drugs had no remarkable effects on the radio sensitivity. Taken together, radiotherapy combined with Cetuximab may be a promising strategy to improve the therapeutic gain for cervical squamous carcinoma patients.

The phosphorylation of EGFR^Thr654 is required for nuclear EGFR importing, and our previous study has shown that pEGFR^Thr654 is an independent prognostic factor for the low survival rate of patients with cervical squamous carcinoma.

Aptamers as Reversible Sorting Ligands for Preparation of Cells in Their Native State

Although antibodies are routinely used to label and isolate a desired cell type from a more complex mixture of cells, via either fluorescence-activated cell sorting (FACS) or magnetic-activated cell sorting (MACS), such antibody labeling is not easily reversible. We describe an FACS and MACS compatible method to reversibly label and purify cells using aptamers. Magnetic beads loaded with the epidermal growth factor receptor (EGFR)-binding antagonistic aptamer E07 specifically isolated EGFR-expressing cells, and pure, label-free cells were recovered via treatment with an "antidote" oligonucleotide complementary to the aptamer. Additionally, while FACS sorting cells with E07 or EGFR antibody yielded EGFR(+) cells with impeded EGFR signaling, stripping off the aptamer via antidote treatment restored receptor function, returning cells to their native state, which was not possible with the antibody. The ability to reversibly label or isolate cells without compromising their function is a valuable, versatile tool with important implications for both the laboratory and clinic.

Sensitizing endometrial cancer to ionizing radiation by multi-tyrosine kinase inhibition

Objective

Endometrial carcinoma is the most frequent gynecological cancer. About 15% of these cancers are of high risk and radiotherapy still remains the most suitable treatment. In this context, agents able to promote radiosensitization are of great interest. Here, we describe for the first time the radiosensitization ability of sunitinib in endometrial carcinoma.

Methods

Four endometrial carcinoma cell lines were used for the study. The activation of apoptosis signalling pathways and tyrosine kinase receptors were analysed by Western blot, luciferase assays and Immunoprecipitation. Radiosensitization effects were assessed using clonogenic assays. p65 and phosphatase and tensin homolog (PTEN) were upregulated by lentiviral transduction.

Results

We discovered that ionizing radiation activates the pro-oncogenic proteins and signalling pathways KIT, protein kinase B (AKT), and nuclear factor kappa B (NF-κB) and these activations were abrogated by sunitinib, resulting in a radiosensitization effect. We found out that AKT pathway is greatly involved in this process as PTEN restoration in the PTEN-deficient cell line RL95-2 is sufficient to inhibit AKT, rendering these cells more susceptible to ionizing radiation and sunitinib-induced radiosensitization. In Ishikawa 3-H-12 cells, radiosensitization effects and inhibition of AKT were achieved by PTEN restoration plus treatment with the phosphoinositide-3-kinase inhibitor LY294002. This suggests that endometrial tumors could have different sensitivity degree to radiotherapy and susceptibility to sunitinib-induced radiosensitization depending on their AKT activation levels.

Conclusions

Our results provide the rationale of using sunitinib as neoadjuvant treatment prior radiotherapy which could be a starting point for the implementation of sunitinib and radiotherapy in the clinic for the treatment of recalcitrant endometrial cancers.

Radiation Modifiers

Radiation therapy is one of the most commonly used treatments for cancer. Radiation modifiers are agents that alter tumor or normal tissue response to radiation, such as radiation sensitizers and radiation protectors. Radiation sensitizers target aspects of tumor molecular biology or physiology to enhance tumor cell killing after irradiation. Radioprotectors prevent damage of normal tissues selectively. Radiation modifiers remain largely investigational at present, with the promise that molecular characterization of tumors may enhance the capacity for successful clinical development moving forward. A variety of radiation modifiers are described.

Single-cell RNA-seq of esophageal squamous cell carcinoma cell line with fractionated irradiation reveals radioresistant gene expression patterns

Background

Esophageal squamous cell carcinoma (ESCC) cells are heterogeneous, easily develop radioresistance, and recur. Single-cell RNA-seq (scRNA-seq) is a next-generation sequencing method that can delineate diverse gene expression profiles of individual cells and mining their heterogeneous behaviors in response to irradiation. Our aim was using scRNA-seq to describe the difference between parental cells and cells that acquired radioresistance, and to investigate the dynamic changes of the transcriptome of cells in response to FIR.

Results

We sequenced ESCC cell lines KYSE180 with and without fractionated irradiation (FIR). A total of 218 scRNA-seq libraries were obtained from 88 cells exposed to 12 Gy (KYSE-180-12 Gy), 89 exposed to 30 Gy (KYSE-180-30 Gy), and 41 parental KYSE-180 cells not exposed to FIR. Dynamic gene expression patterns were determined by comprehensive consideration of genes and pathways. Biological experiments showed that KYSE-180 cells became radioresistant after FIR. PCA analysis of scRNA-seq data showed KYSE-180, KYSE-180-12 Gy and KYSE-180-30 Gy cells were discrete away from each other. Two sub-populations found in KYSE-180-12 Gy and only one remained in KYSE-180-30 Gy. This sub-population genes exposure to FIR through 12 Gy to 30 Gy were relevant to the PI3K-AKT pathway, pathways evading apoptosis, tumor cell migration, metastasis, or invasion pathways, and cell differentiation and proliferation pathways. We validated DEGs, such as CFLAR, LAMA5, ITGA6, ITGB4, and SDC4 genes, in these five pathways as radioresistant genes in bulk cell RNA-seq data from ESCC tissue of a ESCC patient treated with radiotherapy and from KYSE-150 cell lines.

Conclusions

Our results delineated the divergent gene expression patterns of individual ESCC cells exposure to FIR, and displayed genes and pathways related to development of radioresistance.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5970-0) contains supplementary material, which is available to authorized users.

Development and characterisation of acquired radioresistant breast cancer cell lines

BACKGROUND

Radiotherapy plays an important role in the multimodal treatment of breast cancer. The response of a breast tumour to radiation depends not only on its innate radiosensitivity but also on tumour repopulation by cells that have developed radioresistance. Development of effective cancer treatments will require further molecular dissection of the processes that contribute to resistance.

METHODS

Radioresistant cell lines were established by exposing MDA-MB-231, MCF-7 and ZR-751 parental cells to increasing weekly doses of radiation. The development of radioresistance was evaluated through proliferation and colony formation assays. Phenotypic characterisation included migration and invasion assays and immunohistochemistry. Transcriptomic data were also generated for preliminary hypothesis generation involving pathway-focused analyses.

RESULTS

Proliferation and colony formation assays confirmed radioresistance. Radioresistant cells exhibited enhanced migration and invasion, with evidence of epithelial-to-mesenchymal-transition. Significantly, acquisition of radioresistance in MCF-7 and ZR-751 cell lines resulted in a loss of expression of both ERα and PgR and an increase in EGFR expression; based on transcriptomic data they changed subtype classification from their parental luminal A to HER2-overexpressing (MCF-7 RR) and normal-like (ZR-751 RR) subtypes, indicating the extent of phenotypic changes and cellular plasticity involved in this process. Radioresistant cell lines derived from ER+ cells also showed a shift from ER to EGFR signalling pathways with increased MAPK and PI3K activity.

CONCLUSIONS

This is the first study to date that extensively describes the development and characterisation of three novel radioresistant breast cancer cell lines through both genetic and phenotypic analysis. More changes were identified between parental cells and their radioresistant derivatives in the ER+ (MCF-7 and ZR-751) compared with the ER- cell line (MDA-MB-231) model; however, multiple and likely interrelated mechanisms were identified that may contribute to the development of acquired resistance to radiotherapy.

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.

Modulators of Redox Metabolism in Head and Neck Cancer

SIGNIFICANCE

Head and neck squamous cell cancer (HNSCC) is a complex disease characterized by high genetic and metabolic heterogeneity. Radiation therapy (RT) alone or combined with systemic chemotherapy is widely used for treatment of HNSCC as definitive treatment or as adjuvant treatment after surgery. Antibodies against epidermal growth factor receptor are used in definitive or palliative treatment. Recent Advances: Emerging targeted therapies against other proteins of interest as well as programmed cell death protein 1 and programmed death-ligand 1 immunotherapies are being explored in clinical trials.

CRITICAL ISSUES

The disease heterogeneity, invasiveness, and resistance to standard of care RT or chemoradiation therapy continue to constitute significant roadblocks for treatment and patients' quality of life (QOL) despite improvements in treatment modality and the emergence of new therapies over the past two decades.

FUTURE DIRECTIONS

As reviewed here, alterations in redox metabolism occur at all stages of HNSCC management, providing opportunities for improved prevention, early detection, response to therapies, and QOL. Bioinformatics and computational systems biology approaches are key to integrate redox effects with multiomics data from cells and clinical specimens and to identify redox modifiers or modifiable target proteins to achieve improved clinical outcomes. Antioxid. Redox Signal.

Synergistic Effects of Weightlessness, Isoproterenol, and Radiation on DNA Damage Response and Cytokine Production in Immune Cells

The implementation of rotating-wall vessels (RWVs) for studying the effect of lack of gravity has attracted attention, especially in the fields of stem cells, tissue regeneration, and cancer research. Immune cells incubated in RWVs exhibit several features of immunosuppression including impaired leukocyte proliferation, cytokine responses, and antibody production. Interestingly, stress hormones influence cellular immune pathways affected by microgravity, such as cell proliferation, apoptosis, DNA repair, and T cell activation. These pathways are crucial defense mechanisms that protect the cell from toxins, pathogens, and radiation. Despite the importance of the adrenergic receptor in regulating the immune system, the effect of microgravity on the adrenergic system has been poorly studied. Thus, we elected to investigate the synergistic effects of isoproterenol (a sympathomimetic drug), radiation, and microgravity in nonstimulated immune cells. Peripheral blood mononuclear cells were treated with the sympathomimetic drug isoproterenol, exposed to 0.8 or 2 Gy γ-radiation, and incubated in RWVs. Mixed model regression analyses showed significant synergistic effects on the expression of the β2-adrenergic receptor gene (ADRB2). Radiation alone increased ADRB2 expression, and cells incubated in microgravity had more DNA strand breaks than cells incubated in normal gravity. We observed radiation-induced cytokine production only in microgravity. Prior treatment with isoproterenol clearly prevents most of the microgravity-mediated effects. RWVs may be a useful tool to provide insight into novel regulatory pathways, providing benefit not only to astronauts but also to patients suffering from immune disorders or undergoing radiotherapy.

Targeted and Off-Target (Bystander and Abscopal) Effects of Radiation Therapy: Redox Mechanisms and Risk/Benefit Analysis

SIGNIFICANCE

Radiation therapy (from external beams to unsealed and sealed radionuclide sources) takes advantage of the detrimental effects of the clustered production of radicals and reactive oxygen species (ROS). Research has mainly focused on the interaction of radiation with water, which is the major constituent of living beings, and with nuclear DNA, which contains the genetic information. This led to the so-called target theory according to which cells have to be hit by ionizing particles to elicit an important biological response, including cell death. In cancer therapy, the Poisson law and linear quadratic mathematical models have been used to describe the probability of hits per cell as a function of the radiation dose. Recent Advances: However, in the last 20 years, many studies have shown that radiation generates "danger" signals that propagate from irradiated to nonirradiated cells, leading to bystander and other off-target effects.

CRITICAL ISSUES

Like for targeted effects, redox mechanisms play a key role also in off-target effects through transmission of ROS and reactive nitrogen species (RNS), and also of cytokines, ATP, and extracellular DNA. Particularly, nuclear factor kappa B is essential for triggering self-sustained production of ROS and RNS, thus making the bystander response similar to inflammation. In some therapeutic cases, this phenomenon is associated with recruitment of immune cells that are involved in distant irradiation effects (called "away-from-target" i.e., abscopal effects).

FUTURE DIRECTIONS

Determining the contribution of targeted and off-target effects in the clinic is still challenging. This has important consequences not only in radiotherapy but also possibly in diagnostic procedures and in radiation protection.

Molecular analysis of the dual targeting of the epidermal growth factor receptor and the O6-methylguanine-DNA methyltransferase with a double arm hybrid molecule

Disordered expression of the epidermal growth factor receptor (EGFR) has been associated with induction of DNA repair genes (e.g. XRCC1, ERCC1) and resistance to radiation and genotoxic drugs. However, our previous work showed that EGFR inhibition did not affect O⁶-methylguanine-DNA methyltransferase (MGMT)-mediated resistance. In order to block uncoupled events associated with EGFR and MGMT, we designed MR30, a single molecule termed “combi-molecule” that contains a quinazoline arm targeted to EGFR and an O⁶-benzylguanine (O⁶-BG) moiety to block MGMT. Molecular analysis of the mechanism of action of its two arms showed that: (a) it could block EGFR phosphorylation, (b) down-regulate the RAF-MAPK and the PI3K-AKT pathways, and (c) covalently modify MGMT through S-benzylation, as confirmed by MALDI analysis of a direct binding assay with isolated MGMT, (d) it induced a dose-dependent down-regulation of MGMT in lung and melanoma cells. The pleiotropic mechanism of action of MR30 culminated into strong growth inhibition (IC₅₀: 0.018-6.02 μM), with superior activity when compared with an equimolar combination of gefitinib (a clinical EGFR inhibitor) and O⁶-BG (a known MGMT inhibitor). Pulse exposure experiments were required to attenuate the contribution of EGFR inhibition to the strong potency of MR30, thereby allowing to achieve the dose level required to sensitize cells to temozolomide (TMZ). Indeed, MR30 significantly sensitized EGFR-MGMT co-expressing cells to TMZ (p<0.05-0.0001). The results in toto suggest that MR30 is the first prototype of agents that may be used against tumours addicted to EGFR and to sensitize resistant tumours co-expressing EGFR and MGMT to TMZ.

Postoperative Bio-Chemoradiotherapy Using Cetuximab and Docetaxel in Patients With Cis-Platinum-Intolerant Core High-Risk Head and Neck Cancer: Protocol of a Phase 2 Nonrandomized Clinical Trial

Background

We confirmed the safety of postoperative bio-chemoradiotherapy using cetuximab and docetaxel in a small number of patients with cis-platinum–intolerant core high-risk head and neck cancer.

Objective

To assess treatment efficacy, we planned a phase 2 study of postoperative bio-chemoradiotherapy for patients with cis-platinum–intolerant core high-risk head and neck cancer and will compare the results to those of previously collected radiotherapy data.

Methods

Patients who underwent definitive surgery for oral cavity, laryngeal, oropharyngeal, or hypopharyngeal advanced cancer, whose postoperative pathological results indicated core high risk for recurrence (eg, positive margin in the primary site or extranodal extension) and who were cis-platinum–intolerant, will undergo postoperative bio-chemoradiotherapy. The primary end point is 2-year disease-free survival.

Results

The expected 2-year disease-free survival is set at 55%, and the calculated sample size is 35 patients, according to a statistical analysis based on previous reports.

Conclusions

This treatment method is expected to improve the survival rate of patients with severe head and neck cancer.

Trial Registration

UMIN Clinical Trials Registry UMIN000031835; https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ ctr_view.cgi?recptno=R000036355 (Archived by WebCite at http://www.webcitation.org/71fejVjMr)

EGFR-directed monoclonal antibodies in combination with chemotherapy for treatment of non-small-cell lung cancer: an updated review of clinical trials and new perspectives in biomarkers analysis

Lung cancer still represents one of the most common and fatal neoplasm, accounting for nearly 30% of all cancer-related deaths. Targeted therapies based on molecular tumor features and programmed death-1 (PD-1)/programmed death ligand-1 (PDL-1) blockade immunotherapy have offered new therapeutic options for patients with advanced non-small-cell lung cancer (NSCLC). Activation of the epidermal growth factor receptor (EGFR)-pathway promotes tumor growth and progression, including angiogenesis, invasion, metastasis and inhibition of apoptosis, providing a strong rationale for targeting this pathway. EGFR expression is detected in up to 85% of NSCLC and has been demonstrated to be associated with poor prognosis. Two approaches for blocking EGFR signaling are available: prevention of ligand binding to the extracellular domain with monoclonal antibodies (mAbs) and inhibition of the intracellular tyrosine kinase activity with small molecules. There is a strong rationale to consider the tumor's level of EGFR expression as one of the most significant predictive biomarkers in this setting. In this paper we provide an update focusing on the current status of EGFR-directed mAbs use for the treatment of patients with advanced NSCLC, through a review of all clinical trials involving anti-EGFR mAbs in combination with chemotherapy (CT) for advanced disease and with chemo-radiotherapy for stage III disease. Here we also discuss the current status of predictive biomarkers for anti-EGFR mAbs when added to first-line CT in patients with advanced NSCLC. Finally, we focused on the relevance of EGFR fluorescence in situ hybridization (FISH)+ and immunohistochemistry (IHC)-Score ≥ 200 as predictive biomarkers for the selection of patients who would be most likely to derive a clinical benefit from treatment with CT in combination with anti-EGFR mAbs, with particular reference also to histology.

Recovery From Rheumatoid Arthritis Following 15 Months of Therapy With Low Doses of Ionizing Radiation: A Case Report

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease that occurs commonly in old people. Hot spring radon therapy is widely practiced in Central Europe and Japan for relief from the painful symptoms. The usual duration of a spa treatment is a week or two, and the relief is temporary. This article reports on the near-complete recovery of a patient who had been suffering from RA for 10 years. The patient received 15 months of low-dose radon and γ-radiation therapy in a room that reproduced the conditions of a radon spa. The daily 40-minute exposure in the therapy room was supplemented by ten 6-minute radio-nebulizer treatments. The inflammation markers C-reactive protein and matrix metalloproteinase 3 declined strongly to the normal level of 0.07 mg/dL and the near-normal level of 48.9 ng/mL, respectively. After the patient's return to good health, the frequency of the visits was reduced to twice each month. The patient's protection systems appear to have adapted to stimulated conditions, sufficiently to sustain the recovery from RA. Such a long-term course of treatments and follow-up maintenance could be carried out in any hospital that has these low-dose radiation therapy rooms. The therapy could be scheduled to suit patient availability.

Combined irradiation and targeted therapy or immune checkpoint blockade in brain metastases: toxicities and efficacy

Background

Targeted therapies (TT) and immune checkpoint inhibitors (ICI) are currently modifying the landscape of metastatic cancer management and are increasingly used over the course of many cancers treatment. They allow long-term survival with controlled extra-cerebral disease, contributing to the increasing incidence of brain metastases (BMs). Radiation therapy remains the cornerstone of BMs treatment (either whole brain irradiation or stereotactic radiosurgery), and investigating the safety profile of radiation therapy combined with TT or ICI is of high interest. Discontinuing an efficient systemic therapy, when BMs irradiation is considered, might allow systemic disease progression and, on the other hand, the mechanisms of action of these two therapeutic modalities might lead to unexpected toxicities and/or greater efficacy, when combined.

Patients and methods

We carried out a systematic literature review focusing on the safety profile and the efficacy of BMs radiation therapy combined with targeted agents or ICI, emphasizing on the role (if any) of the sequence of combination scheme (drug given before, during, and/or after radiation therapy).

Results

Whereas no relevant toxicity has been noticed with most of these drugs, the concomitant use of some other drugs with brain irradiation requires caution.

Conclusion

Most of available studies appear to advocate for TT or ICI combination with radiation therapy, without altering the clinical safety profiles, allowing the maintenance of systemic treatments when stereotactic radiation therapy is considered. Cognitive functions, health-related quality of life and radiation necrosis risk remain to be assessed. The results of prospective studies are awaited in order to complete and validate the above discussed retrospective data.

Dual blockade of PI3K and MEK in combination with radiation in head and neck cancer

Background and purpose

In this study we have combined fractionated radiation treatment (RT) with two molecular targeted agents active against key deregulated signaling pathways in head and neck cancer.

Materials and methods

We used two molecularly characterized, low passage HNSCC cell lines of differing biological characteristics to study the effects of binimetinib and buparlisib in combination with radiation in vitro and in vivo.

Results

Buparlisib was active against both cell lines in vitro whereas binimetinib was more toxic to UT-SCC-14. Neither agent modified radiation sensitivity in vitro. Buparlisib significantly inhibited growth of UT-SSC-15 alone or in combination with RT but was ineffective in UT-SCC-14. Binimetinib did cause a significant delay with RT in UT-SCC-14 and it significantly reduced growth of the UT-SCC-15 tumors both alone and with RT. The tri-modality treatment was not as effective as RT with a single effective agent.

Conclusions

No significant benefit was gained by the combined use of the two agents with RT even though each was efficacious when used alone.

EGFRvIII expression triggers a metabolic dependency and therapeutic vulnerability sensitive to autophagy inhibition

Expression of EGFRvIII is frequently observed in glioblastoma and is associated with increased cellular proliferation, enhanced tolerance to metabolic stresses, accelerated tumor growth, therapy resistance and poor prognosis. We observed that expression of EGFRvIII elevates the activation of macroautophagy/autophagy during starvation and hypoxia and explored the underlying mechanism and consequence. Autophagy was inhibited (genetically or pharmacologically) and its consequence for tolerance to metabolic stress and its therapeutic potential in (EGFRvIII+) glioblastoma was assessed in cellular systems, (patient derived) tumor xenopgrafts and glioblastoma patients. Autophagy inhibition abrogated the enhanced proliferation and survival advantage of EGFRvIII+ cells during stress conditions, decreased tumor hypoxia and delayed tumor growth in EGFRvIII+ tumors. These effects can be attributed to the supporting role of autophagy in meeting the high metabolic demand of EGFRvIII+ cells. As hypoxic tumor cells greatly contribute to therapy resistance, autophagy inhibition revokes the radioresistant phenotype of EGFRvIII+ tumors in (patient derived) xenograft tumors. In line with these findings, retrospective analysis of glioblastoma patients indicated that chloroquine treatment improves survival of all glioblastoma patients, but patients with EGFRvIII+ glioblastoma benefited most. Our findings disclose the unique autophagy dependency of EGFRvIII+ glioblastoma as a therapeutic opportunity. Chloroquine treatment may therefore be considered as an additional treatment strategy for glioblastoma patients and can reverse the worse prognosis of patients with EGFRvIII+ glioblastoma.

A phase II Study Evaluating Combined Neoadjuvant Cetuximab and Chemotherapy Followed by Chemoradiotherapy and Concomitant Cetuximab in Locoregional Oesophageal Cancer Patients

BACKGROUND

Pre-operative chemoradiotherapy using a 5-fluorouracil (5-FU)/cisplatin backbone is widely used to improve surgical outcomes in locoregional oesophageal cancer patients, despite a non-negligible failure rate.

OBJECTIVE

We evaluated intensification of this approach to improve patient outcomes by adding cetuximab to induction 5-FU/cisplatin/docetaxel (TPF) and to chemoradiotherapy in a phase II study.

PATIENTS AND METHODS

Between November 2006 and April 2009, 50 patients with stage II-IVa squamous cell carcinoma (SCC) or adenocarcinoma of the oesophagus or gastro-oesophageal junction initiated three TPF/cetuximab cycles. Six weeks later, patients with response or stabilisation initiated 6 weeks of cisplatin/cetuximab/radiotherapy, followed by surgery. The primary objective was the clinical complete response (cCR) rate after induction therapy plus chemoradiotherapy in intent-to-treat patients.

RESULTS

Thirty-eight patients were evaluable after chemoradiotherapy, 84% of whom showed disease control. Six patients (12%) achieved a cCR, with a 54% overall response rate. Twenty-seven patients underwent surgery, 11 of whom (22%; nine SCC, two adenocarcinoma) had a pathological CR (41%). Fifteen patients were alive after a median follow-up of 23.2 months. Median progression-free survival was 12.2 months (95% confidence interval [CI] 1.7-22.8). Median overall survival was 23.4 months (95% CI 12.2-36.6) and was significantly longer among the 22 patients with complete resection than in the five patients without (42.1 vs. 24.9 months; p = 0.02, hazard ratio: 3.6, 95% CI 1.1-11.6). The toxicity profile was acceptable.

CONCLUSIONS

Neoadjuvant cetuximab/TPF followed by chemoradiotherapy in locoregional oesophageal carcinoma patients is feasible and offers a modest response rate in this trial. The results of combining trimodality neoadjuvant treatment with cetuximab are consistent with the literature. Registration: The study is registered at ClinicalTrials.gov (NCT00733889).

Biological determinants of radioresistance and their remediation in pancreatic cancer

Despite recent advances in radiotherapy, a majority of patients diagnosed with pancreatic cancer (PC) do not achieve objective responses due to the existence of intrinsic and acquired radioresistance. Identification of molecular mechanisms that compromise the efficacy of radiation therapy and targeting these pathways is paramount for improving radiation response in PC patients. In this review, we have summarized molecular mechanisms associated with the radio-resistant phenotype of PC. Briefly, we discuss the reversible and irreversible biological consequences of radiotherapy, such as DNA damage and DNA repair, mechanisms of cancer cell survival and radiation-induced apoptosis following radiotherapy. We further describe various small molecule inhibitors and molecular targeting agents currently being tested in preclinical and clinical studies as potential radiosensitizers for PC. Notably, we draw attention towards the confounding effects of cancer stem cells, immune system, and the tumor microenvironment in the context of PC radioresistance and radiosensitization. Finally, we discuss the need for examining selective radioprotectors in light of the emerging evidence on radiation toxicity to non-target tissue associated with PC radiotherapy.

Efficacy and safety results of ABT-414 in combination with radiation and temozolomide in newly diagnosed glioblastoma

BACKGROUND

The purpose of this study was to determine the maximum tolerated dose (MTD), recommended phase II dose (RPTD), safety, and pharmacokinetics of ABT-414 plus radiation and temozolomide in newly diagnosed glioblastoma. ABT-414 is a first-in-class, tumor-specific antibody-drug conjugate that preferentially targets tumors expressing overactive epidermal growth factor receptor (EGFR).

METHODS

In this multicenter phase I study, patients received 0.5-3.2 mg/kg ABT-414 every 2 weeks by intravenous infusion. EGFR alterations, O6-methylguanine-DNA methyltransferase (MGMT) promoter hypermethylation, and isocitrate dehydrogenase (IDH1) gene mutations were assessed in patient tumors. Distinct prognostic classes were assigned to patients based on a Molecular Classification Predictor model.

RESULTS

As of January 7, 2016, forty-five patients were enrolled to receive ABT-414 plus radiation and temozolomide. The most common treatment emergent adverse events were ocular: blurred vision, dry eye, keratitis, photophobia, and eye pain. Ocular toxicity at any grade occurred in 40 patients and at grades 3/4 in 12 patients. RPTD and MTD were set at 2 mg/kg and 2.4 mg/kg, respectively. Among 38 patients with pretreatment tumor tested centrally, 39% harbored EGFR amplification, of which 73% had EGFRvIII mutation. Among patients with available tumor tissue (n = 30), 30% showed MGMT promoter methylation and none had IDH1 mutations. ABT-414 demonstrated an approximately dose proportional pharmacokinetic profile. The median duration of progression-free survival was 6.1 months; median overall survival has not been reached.

CONCLUSION

ABT-414 plus chemoradiation demonstrated an acceptable safety and pharmacokinetic profile in newly diagnosed glioblastoma. Randomized studies are ongoing to determine efficacy in newly diagnosed (NCT02573324) and recurrent glioblastoma (NCT02343406).

Targeted Therapy in Head and Neck Cancer: An Update on Current Clinical Developments in Epidermal Growth Factor Receptor-Targeted Therapy and Immunotherapies

Most patients diagnosed with head and neck squamous cell carcinoma (HNSCC) will present with locally advanced disease, requiring multimodality therapy. Despite this curative approach, a significant subset of these patients will develop locoregional failure and/or distant metastases. Despite significant progress in the treatment and subsequent prognosis of locally advanced HNSCC, the prognosis of those patients with recurrent and/or metastatic (R/M) HNSCC is poor, with short-lived responses to palliative chemotherapy and few therapeutic agents available. The discovery of the integral role of epidermal growth factor receptor overexpression in the pathogenesis of HNSCC, coupled with emerging data on the role of tumor evasion of the immune system, has opened new pathways in the development of novel therapeutic agents for the treatment of R/M HNSCC. As a result, cetuximab, a monoclonal antibody targeting epidermal growth factor receptor, as well as pembrolizumab and nivolumab, monoclonal antibodies targeting programmed cell death 1 (PD-1), are now US Food and Drug Administration approved for the treatment of R/M HNSCC. This review will detail the data supporting the use of these agents, as well as clinical trials evaluating the efficacy of other novel and promising drugs.

Targeting the AKT pathway: Repositioning HIV protease inhibitors as radiosensitizers

Cellular resistance in tumour cells to different therapeutic approaches has been a limiting factor in the curative treatment of cancer. Resistance to therapeutic radiation is a common phenomenon which significantly reduces treatment options and impacts survival. One of the mechanisms of acquiring resistance to ionizing radiation is the overexpression or activation of various oncogenes like the EGFR (epidermal growth factor receptor), RAS (rat sarcoma) oncogene or loss of PTEN (phosphatase and tensin homologue) which in turn activates the phosphatidyl inositol 3-kinase/protein kinase B (PI3-K)/AKT pathway responsible for radiation resistance in various tumours. Blocking the pathway enhances the radiation response both in vitro and in vivo. Due to the differential activation of this pathway (constitutively activated in tumour cells and not in the normal host cells), it is an excellent candidate target for molecular targeted therapy to enhance radiation sensitivity. In this regard, HIV protease inhibitors (HPIs) known to interfere with PI3-K/AKT signaling in tumour cells, have been shown to sensitize various tumour cells to radiation both in vitro and in vivo. As a result, HPIs are now being investigated as possible radiosensitizers along with various chemotherapeutic drugs. This review describes the mechanisms by which PI3-K/AKT pathway causes radioresistance and the role of HIV protease inhibitors especially nelfinavir as a potential candidate drug to target the AKT pathway for overcoming radioresistance and its use in various clinical trials for different malignancies.

From chemotherapy to target therapies associated with radiation in the treatment of NSCLC: a durable marriage?

INTRODUCTION

The integration between radiotherapy and drugs, from chemotherapy to recently available target therapies, continues to have a relevant role in the treatment of locally advanced and metastatic Non-small cell lung cancer (NSCLC). Aim of the present review is to evaluate the promising and emerging application of the best interaction between new drugs and new modalities of radiotherapy. Areas covered: We searched Medline, Google Scholar, PubMed, ProQuest Dissertation, and Theses databases for reports published in English. A study was included when it reported on cancer-related radiotherapy and included patients with NSCLC treated with chemo and/or target therapies. Review articles were excluded from the analysis. Expert commentary: Chemo-radiotherapy still represents the standard of choice in locally advanced NSCLC, while to date the addition of target therapies to chemo-radiotherapy did not demonstrate any robust advantage in this stage of disease. Considering the absence of randomized controlled trials, the role of target therapies in early stage adjuvant NSCLC is not yet recommended in clinical practice. On the contrary, in the setting of oligometastatic and oligoprogressive disease, new molecules demonstrated to be safe and effective, opening to a promising and emerging application of the best interaction between new drugs and new modalities of radiotherapy.

Brain Metastases from NSCLC: Radiation Therapy in the Era of Targeted Therapies

Brain metastases (BMs) will develop in a large proportion of patients with NSCLC throughout the course of their disease. Among patients with NSCLC with oncogenic drivers, mainly EGFR activating mutations and anaplastic lymphoma receptor tyrosine kinase gene (ALK) rearrangements, the presence of BM is a common secondary localization of disease both at the time of diagnosis and at relapse. Because of the limited penetration of a wide range of drugs across the blood-brain barrier, radiotherapy is considered the cornerstone of treatment of BMs. However, evidence of dramatic intracranial response rates has been reported in recent years with targeted therapies such as tyrosine kinase inhibitors and has been supported by new insights into pharmacokinetics to increase rates of tyrosine kinase inhibitors' penetration of the cerebrospinal fluid (CSF). In this context, the combination of brain radiotherapy and targeted therapies seems relevant, and there is a strong radiobiological rationale to harness the radiosentizing effect of the drugs. Nevertheless, to date, there is a paucity of high-level clinical evidence supporting the combination of brain radiotherapy and targeted therapies in patients with NSCLC and BMs, and there are often methodological biases in reported studies, such as the lack of stratification by mutation status. Moreover, among asymptomatic patients not suitable for ablative treatment, this strategy is challenged by the promising results associated with the administration of targeted therapies alone. Herein, we review the biological rationale to combine targeted therapies and brain radiotherapy for patients with NSCLC and BMs, report the clinical data available to date, and discuss future directions to improve outcome in this group of patients.

[Radiotherapy and targeted therapy/immunotherapy]

Thanks to recent advances achieved in oncologic systemic and local ablative treatment, the treatments become more and more efficient in term of local control and overall survival. Thus, the targeted therapies, immunotherapy or stereotactic radiotherapy have modified the management of patients, especially in case of oligometastatic disease. Many questions are raised by these innovations, particularly the diagnosis and management of new side effects or that of the combination of these different treatments, depending on the type of primary tumor. Fundamental data are available, while clinical data are still limited. Ongoing trials should help to clarify the clinical management protocols. This manuscript is a review of the combination of radiotherapy and targeted therapy/immunotherapy.

Effects of epidermal growth factor receptor kinase inhibition on radiation response in canine osteosarcoma cells

BACKGROUND

Radiation therapy is a palliative treatment modality for canine osteosarcoma, with transient improvement in analgesia observed in many cases. However there is room for improvement in outcome for these patients. It is possible that the addition of sensitizing agents may increase tumor response to radiation therapy and prolong quality of life. Epidermal growth factor receptor (EGFR) expression has been documented in canine osteosarcoma and higher EGFR levels have been correlated to a worse prognosis. However, effects of EGFR inhibition on radiation responsiveness in canine osteosarcoma have not been previously characterized. This study examined the effects of the small molecule EGFR inhibitor erlotinib on canine osteosarcoma radiation responses, target and downstream protein expression in vitro. Additionally, to assess the potential impact of treatment on tumor angiogenesis, vascular endothelial growth factor (VEGF) levels in conditioned media were measured.

RESULTS

Erlotinib as a single agent reduced clonogenic survival in two canine osteosarcoma cell lines and enhanced the impact of radiation in one out of three cell lines investigated. In cell viability assays, erlotinib enhanced radiation effects and demonstrated single agent effects. Erlotinib did not alter total levels of EGFR, nor inhibit downstream protein kinase B (PKB/Akt) activation. On the contrary, erlotinib treatment increased phosphorylated Akt in these osteosarcoma cell lines. VEGF levels in conditioned media increased after erlotinib treatment as a single agent and in combination with radiation in two out of three cell lines investigated. However, VEGF levels decreased with erlotinib treatment in the third cell line.

CONCLUSIONS

Erlotinib treatment promoted modest enhancement of radiation effects in canine osteosarcoma cells, and possessed activity as a single agent in some cell lines, indicating a potential role for EGFR inhibition in the treatment of a subset of osteosarcoma patients. The relative radioresistance of osteosarcoma cells does not appear to be related to EGFR signalling exclusively. Angiogenic responses to radiation and kinase inhibitors are similarly likely to be multifactorial and require further investigation.

Mechanisms of skin aging induced by EGFR inhibitors

BACKGROUND

The mechanisms of skin aging have not been completely elucidated. Anecdotal data suggests that EGFR inhibition accelerates aging-like skin changes.

OBJECTIVE

The objective of the study was to evaluate the clinical characteristics and investigate the cellular and molecular mechanisms underlying skin changes associated with the use of EFGRIs.

PATIENTS AND METHODS

Patients during prolonged treatment with EGFRIs (>3 months) were analyzed for aging-like skin changes. Baseline EGFR expression was compared in young (<25 years old) vs. old (> 65 years old) skin. In addition, the regulation of extracellular matrix, senescence-associated genes, and cell cycle status was measured in primary human keratinocytes treated with erlotinib in vitro.

RESULTS

There were progressive signs of skin aging, including xerosis cutis, atrophy, rhytide formation, and/or actinic purpura in 12 patients. Keratinocytes treated with erlotinib in vitro showed a significant down-modulation of hyaluronan synthases (HAS2 and HAS3), whereas senescence-associated genes (p21, p53, IL-6, maspin) were upregulated, along with a G1 cell cycle arrest and stronger SA β-Gal activity. There was significantly decreased baseline expression in EGFR density in aged skin, when compared to young controls.

CONCLUSIONS

EGFR inhibition results in molecular alterations in keratinocytes that may contribute to the observed skin aging of patients treated with respective targeted agents.

Targeted therapy combined with radiotherapy in non-small-cell lung cancer: a review of the Oncologic Group for the Study of Lung Cancer (Spanish Radiation Oncology Society)

In recent years, major advances in our understanding of the molecular biology of lung cancer, together with significant improvements in radiotherapy technologies, have revolutionized the treatment of non-small cell lung cancer (NSCLC). This has led to the development of new therapies that target molecular mutations specific to each tumor type, acting on the cell surface antigens or intracellular signaling pathways, or directly affecting cell survival. At the same time, ablative dose radiotherapy can be delivered safely in the context of metastatic disease. In this article, the GOECP/SEOR (Oncological Group for Study of Lung Cancer/Spanish Society of Radiation Oncology) reviews the role of new targeted therapies used in combination with radiotherapy in patients with locally advanced (stage III) NSCLC and in patients with advanced, metastatic (stage IV) NSCLC.