Epidermal Growth Factor Receptor Blockade Research Articles

AZD3759 enhances radiation effects in non-small-cell lung cancer by a synergistic blockade of epidermal growth factor receptor and Janus kinase-1

ABSTRACT AZD3759 is a novel epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) on the basis of gefitinib and has been proven to enter the central nervous system. Although the promising antitumor effects of AZD3759 on non-small cell lung cancer (NSCLC) have been demonstrated in clinical trials, the regulatory effects of this inhibitor on the antitumor efficacy of radiation (RA) are unclear. The present study aimed to compare the effects of AZD3759 and osimertinib on RA efficacy in NSCLC and explore the potential mechanism of action of AZD3759. We found that the survival in RA-treated NSCLC cells was significantly decreased by treatment with 500 nM AZD3759 and osimertinib at the RA dosage of 8 Gy. The apoptotic rate, cell cycle arrest, and DNA damage in RA-treated NSCLC cells and brain metastasis in RA-treated xenograft nude mice were significantly enhanced by the co-administration of AZD3759 and osimertinib, respectively. In addition, AZD3759 showed a significantly stronger efficacy than osimertinib did. Mechanistically, the receptor tyrosine kinase signaling antibody array revealed that Janus kinase-1 (JAK1) was specifically inhibited by AZD3759, but not by osimertinib. The effects of AZD3759 on RA efficacy in PC-9 cells and in a brain metastasis animal model were significantly abolished by the overexpression of JAK1. Collectively, our results suggested that AZD3759 promoted RA antitumor effects in NSCLC by synergistic blockade of EGFR and JAK1.

Randomized phase II trial of avelumab alone or in combination with cetuximab for patients with previously treated, locally advanced, or metastatic squamous cell anal carcinoma: the CARACAS study

BackgroundNo standard therapies beyond first line are established for advanced squamous cell anal carcinoma (aSCAC). Earlier preliminary data suggest activity of epidermal growth factor receptor (EGFR) inhibition and programmed cell...

EGFR signaling promotes resistance to CHK1 inhibitor prexasertib in triple negative breast cancer.

Aim: Innate resistance to the CHK1 inhibitor prexasertib has been described, but resistance mechanisms are not understood. We aimed to determine the role epidermal growth factor receptor (EGFR) plays in innate resistance to prexasertib in triple negative breast cancer (TNBC).Methods: Using a panel of pre-clinical TNBC cell lines, we measured the sensitivity to prexasertib. We examined the effect activation of EGFR had on prexasertib sensitivity. We measured the synergy of dual blockade of EGFR with erlotinib and CHK1 with prexasertib in TNBC cell lines and xenografts.Results: EGFR overexpression and activation increased resistance to CHK1 inhibition by prexasertib. EGFR promoted the phosphorylation of BCL2-associated agonist of cell death (BAD), inactivating its pro-apoptotic functions. Inhibition of EGFR reversed BAD phosphorylation, increasing sensitivity to prexasertib.Conclusion: The use of prexasertib as a monotherapy in TNBC has been limited due to modest clinical responses. We demonstrated that EGFR activation contributes to innate resistance to prexasertib in TNBC and potentially other cancers. EGFR expression status should be considered in clinical trials examining prexasertib’s use as a monotherapy or combination therapy.

Dual inhibition of EGFR and IL-6-STAT3 signalling by miR-146b: a potential targeted therapy for epithelial ovarian cancer

Epidermal growth factor receptor (EGFR) signalling and the interleukin-6 (IL-6)/signal transducer and activator of transcription 3 (STAT3) are aberrantly activated in ovarian cancer. However, inhibition of EGFR signalling in ovarian cancer patients resulted in a disappointing clinical benefit. In this study, we found that EGFR could activate IL-6-STAT3 pathway in ovarian cancer cells. However, we also demonstrated that EGFR knockdown could increase STAT3 phosphorylation in HO8910 and OVCAR-3 ovarian cancer cells. Interestingly, we further demonstrated that the non-coding RNA miR-146b could simultaneously block both the EGFR and IL-6-STAT3 pathways. Finally, our data demonstrated that miR-146b overexpression resulted in a greater suppression of cell migration than STAT3 pathway inhibition alone.These results suggest a complex and heterogeneous role of EGFR in ovarian cancer. Combined blockade of EGFR and IL-6-STAT3 pathways by miR-146b might be a strategy for improving the clinical benefit of targeting the EGFR pathway in ovarian cancer patients in the future.

Tumor-targeting anti-EGFR x anti-PD1 bispecific antibody inhibits EGFR-overexpressing tumor growth by combining EGFR blockade and immune activation with direct tumor cell killing

We developed a strategy to combine conventional targeted therapy with immune checkpoint blockade using a tumor-targeting bispecific antibody (BsAb) to treat solid tumors. The BsAb was designed to simultaneously engage a tumor-associated antigen, epidermal growth factor receptor (EGFR), and programed cell death protein 1 (PD1). In addition to its direct anti-tumor activity via EGFR inhibition, the BsAb mediated efficient antibody-dependent cellular cytotoxicity (ADCC) and activated T cell antitumor im munity through blockade of PD1 from interacting with its counterpart, programed cell death ligand 1 (PDL1). Further, the BsAb exhibited a potent direct tumor cell killing activity in the presence of PBMC, most likely, via activating and, at the same time, physically engaging T cells with tumor cells. Taken together, we here illustrate a new strategy in the design and production of novel BsAbs with enhanced therapeutic efficacy through both direct tumor growth inhibition and T cell activation via tumor-targeted immune checkpoint blockade.

Cetuximab-Mediated Protection from Hypoxia- Induced Cell Death: Implications for Therapy Sequence in Colorectal Cancer.

Simple SummaryTherapeutic antibodies are an integral part of treatment regimens for metastasized colorectal cancer. In KRAS wildtype tumors both bevacizumab and cetuximab are active. While bevacizumab has previously been shown to induce tumor hypoxia, we here report that EGFR inhibition by cetuximab protects colon cancer cells from hypoxia-induced cell death. This effect appears to be responsible for the inferior efficacy of a treatment sequence of bevacizumab followed by cetuximab versus an inverse sequence that we observed in a colorectal cancer mouse model. It also offers a mechanistic explanation for effects observed in clinical trials such as underadditive or even detrimental effects when combining bevacizumab and cetuximab (CAIRO2 trial) and the superior efficacy of first line cetuximab (FIRE-3 trial) under chemotherapy backbones in colorectal cancer.Monoclonal antibodies like cetuximab, targeting the epidermal growth factor receptor (EGFR), and bevacizumab, targeting the vascular endothelial growth factor (VEGF), are an integral part of treatment regimens for metastasized colorectal cancer. However, inhibition of the EGFR has been shown to protect human glioma cells from cell death under hypoxic conditions. In colon carcinoma cells, the consequences of EGFR blockade in hypoxia (e.g., induced by bevacizumab) have not been evaluated yet. LIM1215 and SW948 colon carcinoma and LNT-229 glioblastoma cells were treated with cetuximab, PD153035, and erlotinib and analyzed for cell density and viability. The sequential administration of either cetuximab followed by bevacizumab (CET->BEV) or bevacizumab followed by cetuximab (BEV->CET) was investigated in a LIM1215 (KRAS wildtype) and SW948 (KRAS mutant) xenograft mouse model. In vitro, cetuximab protected from hypoxia. In the LIM1215 model, a survival benefit with cetuximab and bevacizumab monotherapy was observed, but only the sequence CET->BEV showed an additional benefit. This effect was confirmed in the SW948 model. Our observations support the hypothesis that bevacizumab modulates the tumor microenvironment (e.g., by inducing hypoxia) where cetuximab could trigger protective effects when administered later on. The sequence CET->BEV therefore seems to be superior as possible mutual adverse effects are bypassed.

Abstract 4260: Molecular imaging of glutamine (Gln) metabolism in RAS wildtype (WT) metastatic colorectal cancer (mCRC)

Abstract Background: Gln metabolism plays a critical role in cancer. In CRC, the epidermal growth factor receptor (EGFR) and Gln cooperate to provide signal transduction and fuel for mitogen activated protein kinase-dependent cell growth. Our preclinical data illustrate that Gln abrogates EGFR inhibition and blockade of Gln metabolism restores EGFR sensitivity, forming the basis of a phase I/II clinical trial exploring dual EGFR and Gln metabolism in mCRC (NCT03263429). As a biomarker correlate, we are performing dual tracer PET imaging of Gln flux (11C-Gln) and Gln to glutamate conversion (18F-FSPG). We hypothesize that tumors dependent on Gln will exhibit high 11C-Gln uptake at baseline, while inhibition of Gln metabolism will reduce 18F-FSPG uptake. Notably, this is the first-in-human study with 11C-Gln. Methods: Adult patients (pts) with previously treated anti-EGFR, RAS WT, mCRC are enrolling and receive panitumumab (6 mg/kg Day 1 and 15) and CB-839 (800 mg twice daily) in 28-day treatment cycles. 11C-Gln and 18F-FSPG scans are performed at baseline and Cycle 1 Day 28. Lesion to blood pool ratio (LBR) is calculated for each target lesion and compared with change in tumor size as measured by RECIST 1.1 after 2 cycles of therapy. Results: The study is ongoing. To date, we have collected pre- and post-therapy PET data on 4 pts; individual lesion data for 2 pts are presented in the table. A mixed response with 11C-Gln uptake was observed for Pt #1, which could reflect different underlying lesion pathology; varying degree of lesion size change was also observed in this patient. The greatest decrease in 18F-FSPG uptake corresponded to the lesion with the smallest growth. For Pt #2, 11C-Gln uptake at baseline was highest in the lesion with the largest decrease in tumor size at Day 56; 18F-FSPG uptake was greatly reduced in all lesions, which corresponded to decreases in tumor size. Best overall response was progressive disease and partial response for Pt #1 and #2, respectively. Gln PET as a function of lesion response11C-Gln18F-FSPG% Change in lesion size at Day 56Baseline LBRDay 28 LBR% ChangeBaseline LBRDay 28 LBR% ChangePatient#1L lung nodule+44%2.171.93-11.1%2.001.06-47.0%Posterior hepatic lobe+6%5.404.27-20.9%6.422.84-55.8%Segment IVA liver+107%5.114.88-4.5%5.583.90-30.1%Adrenal mass+152%3.504.4727.7%2.862.84-0.7%Patient#2R infrahilar pulmonary metastasis-15%2.471.74-29.6%3.131.72-45.0%L pulmonary metastasis-15%0.750.784.0%0.960.82-14.6%Hepatic Metastasis #1-100%8.976.81-24.1%7.003.50-50.0% Conclusions: Quantitative biomarkers that predict response early in the course of therapy are a means to achieve the promise of precision medicine. Our preliminary clinical imaging data suggest that the employed investigational PET molecular imaging tracers have potential for prioritizing patients for combined EGFR/Gln targeted therapy and to predict response early in the treatment course. Additional PET data for all pts and summary statistics will be presented. Citation Format: Jennifer Gray Whisenant, Gary Smith, Allison Cohen, Kristen K. Ciombor, Dana Cardin, Cathy Eng, Laura Goff, Satya Das, Tiffany Hickman, Anna Fisher, Adria Payne, Robert Coffey, G. Dan Ayers, Jordan D. Berlin, H. Charles Manning. Molecular imaging of glutamine (Gln) metabolism in RAS wildtype (WT) metastatic colorectal cancer (mCRC) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4260.

Combined blockade of EGFR and glutamine metabolism in preclinical models of colorectal cancer.

Improving response to epidermal growth factor receptor (EGFR)-targeted therapies in patients with advanced wild-type (WT) RAS colorectal cancer (CRC) remains an unmet need. In this preclinical work, we evaluated a new therapeutic combination aimed at enhancing efficacy by targeting cancer cell metabolism in concert with EGFR. We hypothesized that combined blockade of glutamine metabolism and EGFR represents a promising treatment approach by targeting both the “fuel” and “signaling” components that these tumors need to survive. To explore this hypothesis, we combined CB-839, an inhibitor of glutaminase 1 (GLS1), the mitochondrial enzyme responsible for catalyzing conversion of glutamine to glutamate, with cetuximab, an EGFR-targeted monoclonal antibody in preclinical models of CRC. 2D and 3D in vitro assays were executed following treatment with either single agent or combination therapy. The combination of cetuximab with CB-839 resulted in reduced cell viability and demonstrated synergism in several cell lines. In vivo efficacy experiments were performed in cell-line xenograft models propagated in athymic nude mice. Tumor volumes were measured followed by immunohistochemical (IHC) analysis of proliferation (Ki67), mechanistic target of rapamycin (mTOR) signaling (pS6), and multiple mechanisms of cell death to annotate molecular determinants of response. In vivo, a significant reduction in tumor growth and reduced Ki67 and pS6 IHC staining were observed with combination therapy, which was accompanied by increased apoptosis and/or necrosis. The combination showed efficacy in cetuximab-sensitive as well as resistant models. In conclusion, this therapeutic combination represents a promising new precision medicine approach for patients with refractory metastatic WT RAS CRC.

The investigation of the amounts and expressions of epidermal growth factor, epidermal growth factor receptor, and epidermal growth factor receptor gene polymorphisms in acne vulgaris.

Epidermal growth factor receptor inhibitors (EGFRI) used in cancer chemotherapy cause acneiform folliculitis in 70%-100% of patients in a dose-dependent manner. Acneiform folliculitis is considered to be caused by an inflammatory process due to follicular hyperkeratosis and subsequently a set of changes both in epidermis and hair follicles as a result of epidermal growth factor receptor (EGFR) blockade. Both acne vulgaris and acneiform folliculitis due to EGFRIs show similar changes in the pilosebaceous unit. Furthermore, in both groups of patients, topical application of recombinant human epidermal growth factor (EGF) has been reported to improve the disease. In this study, it was aimed to investigate the role of EGF and EGFR amount, expression, and EGFR gene polymorphisms in the etiopathogenesis of acne vulgaris. 156 acne vulgaris patients, within 18-25years of age, who had 15 or more inflammatory acne lesions on dermatologic evaluation were included in this study. The absence of any known systemic or genetic disease or cancer and any systemic or topical treatment for the last 1month were prerequisites. In the control group, 154 volunteers in the same age range who were examined at the outpatient clinic with diagnoses of melanocytic nevus, ephelid, cherry angioma, and callus and who had no more than 3 inflammatory acne lesions were recruited. The amounts of EGF and EGFR were determined by sandwich ELISA, expressions of EGF and EGFR by reverse transcriptase polymerase chain reaction; EGFR polymorphisms were examined by restriction enzyme digestion, Sanger, and high-resolution melting methods. The patient and control groups were compared in terms of EGFR gene polymorphisms in addition to the amount and expressions of EGF and EGFR. The amount of EGF in the serum was found to be significantly higher in the acne group. (P=.0012). There was no significant difference in other parameters studied. The results of our study showed a significant increase in the amount of EGF in the acne group. Though EGF may be incriminated in the etiopathogenesis of AV, the most likely explanation about its role may be controlling inflammation from the very first stage.

MiR-615 Regulates NSC Differentiation In Vitro and Contributes to Spinal Cord Injury Repair by Targeting LINGO-1.

LINGO-1(LRR and Ig domain-containing NOGO receptor interacting protein 1) is a viable target for spinal cord injury (SCI) repair due to its potent negative regulation in neuron survival and axonal regeneration. Although promising, the intracellular mechanism underlying LINGO-1 regulation is unclear. Here, we identified miR-615 as a potential microRNA (miRNA) that directly targets LINGO-1 by binding its 3'-untranslated region (3'-UTR) and caused the translation inhibition of LINGO-1. MiR-615 negatively regulated LINGO-1 during neural stem cell (NSC) differentiation and facilitated its neuronal differentiation in vitro. Interestingly, compared to the control, neurons differentiated from miR-615-treated NSCs were immature with short processes. Further results showed LINGO-1/epidermal growth factor receptor (EGFR) signaling may be involved in this process, as blockade of EGFR using specific antagonist resulted in mature neurons with long processes. Furthermore, intrathecal administration of miR-615 agomir in SCI rats effectively knocked down LINGO-1, increased neuronal survival, enhanced axonal extension and myelination, and improved recovery of hindlimbs motor functions. This work thus uncovers miR-615 as an effective miRNA that regulates LINGO-1 in NSC and SCI animals, and suggests miR-615 as a potential therapeutic target for traumatic central nervous system (CNS) injury.

Immunotherapy in head and neck squamous cell carcinoma : Abscopal effects in combination with radiotherapy, extraordinary responses in combination with chemotherapy, and pseudoprogression

The clinical implementation of immunotherapy has broadened the therapeutic options for recurrent and/or metastatic head and neck squamous cell carcinoma (HNSCC). Until 2016, the only molecularly targeted therapy was epidermal growth factor receptor (EGFR) blockade. However, immune checkpoint inhibition has recently become part of first-line treatment in recurrent and/or metastatic HNSCC. The occurrence of abscopal effects of radiotherapy and synergisms between immunotherapy and chemotherapy as well as the phenomenon of pseudoprogression in HNSCC were investigated. Key publications of recent clinical trials and preclinical studies on the underlying biological mechanisms were analyzed. As already observed in other tumor entities, synergistic effects upon combination of immunotherapy with radio- and/or chemotherapy are observed in the clinical management of recurrent and/or metastatic HNSCC, and this is mediated by (re)activation of host antitumor immune mechanisms. In selected patients, this may be radiologically detected as pseudoprogression. Reliable biomarkers for these phenomena have not yet been clinically established. For recurrent and/or metastatic HNSCC, the occurrence of systemic effects upon radiochemoimmunotherapy in the clinic is on the rise. Hence, the identification of biomarkers for abscopal effects of radiotherapy and unexpected synergisms between chemotherapy and immunotherapy as well as for pseudoprogression is gaining in importance.

Emerging RAS, BRAF, and EGFR mutations in cell-free DNA of metastatic colorectal patients are associated with both primary and secondary resistance to first-line anti-EGFR therapy.

Oncogenic RAS mutations are negative biomarkers of response to epidermal growth factor receptor (EGFR) blockade. RAS mutations are usually detected in biopsies of primary colorectal tumors. However, the genomic profiles of primary tumors and metastases are not always concordant, and chemotherapeutic agents can alter the tumor molecular landscape. Cell-free DNA (cfDNA) is a novel tool to detect molecular heterogeneity. This study evaluated the clinical utility of cfDNA to predict primary or secondary resistance to EGFR blockade in patients with metastatic colorectal cancer. Thirty metastatic colorectal cancer patients without RAS and BRAF mutations were prospectively enrolled and treated with cytotoxic agents and EGFR blockade as first-line therapy. cfDNA was analyzed for the presence of RAS, BRAF, and EGFR (S492R) point mutations before initiating chemotherapy and every 2months during chemotherapy. The analysis was performed in 223 plasma samples from all 30 patients. Of the 30 patients, five had RAS mutations in their cfDNA before starting chemotherapy and did not respond. Twenty-four of the remaining 25 patients without cfDNA RAS mutations had a response. Twenty of the 24 responders developed secondary resistance and cfDNA RAS mutations were found in 17 of the 20. cfDNA BRAF mutations were found in seven, and EGFR mutations were found in eight of the 20 patients. Emerging RAS, BRAF, and EGFR mutations occurred in patients with primary and secondary resistance to EGFR blockade. The detection of these mutations in cfDNA is a promising approach to predict treatment response and secondary resistance.

Vitamin C Restricts the Emergence of Acquired Resistance to EGFR-Targeted Therapies in Colorectal Cancer.

The long-term efficacy of the Epidermal Growth Factor Receptor (EGFR)-targeted antibody cetuximab in advanced colorectal cancer (CRC) patients is limited by the emergence of drug-resistant (persister) cells. Recent studies in other cancer types have shown that cells surviving initial treatment with targeted agents are often vulnerable to alterations in cell metabolism including oxidative stress. Vitamin C (VitC) is an antioxidant agent which can paradoxically trigger oxidative stress at pharmacological dose. Here we tested the hypothesis that VitC in combination with cetuximab could restrain the emergence of secondary resistance to EGFR blockade in CRC RAS/BRAF wild-type models. We found that addition of VitC to cetuximab impairs the emergence of drug persisters, limits the growth of CRC organoids, and significantly delays acquired resistance in CRC patient-derived xenografts. Mechanistically, proteomic and metabolic flux analysis shows that cetuximab blunts carbohydrate metabolism by blocking glucose uptake and glycolysis, beyond promoting slow but progressive ROS production. In parallel, VitC disrupts iron homeostasis and further increases ROS levels ultimately leading to ferroptosis. Combination of VitC and cetuximab orchestrates a synthetic lethal metabolic cell death program triggered by ATP depletion and oxidative stress, which effectively limits the emergence of acquired resistance to anti-EGFR antibodies. Considering that high-dose VitC is known to be safe in cancer patients, our findings might have clinical impact on CRC patients treated with anti-EGFR therapies.

Blockade of EGFR improves responsiveness to PD-1 blockade in EGFR-mutated non-small cell lung cancer.

The clinical efficacy of anti-PD-1 (programmed cell death-1) monoclonal antibody (mAb) against cancers with oncogenic driver gene mutations, which often harbor a low tumor mutation burden, is variable, suggesting different contributions of each driver mutation to immune responses. Here, we investigated the immunological phenotypes in the tumor microenvironment (TME) of epidermal growth factor receptor (EGFR)-mutated lung adenocarcinomas, for which anti-PD-1 mAb is largely ineffective. Whereas EGFR-mutated lung adenocarcinomas had a noninflamed TME, CD4+ effector regulatory T cells, which are generally present in the inflamed TME, showed high infiltration. The EGFR signal activated cJun/cJun N-terminal kinase and reduced interferon regulatory factor-1; the former increased CCL22, which recruits CD4+ regulatory T cells, and the latter decreased CXCL10 and CCL5, which induce CD8+ T cell infiltration. The EGFR inhibitor erlotinib decreased CD4+ effector regulatory T cells infiltration in the TME and in combination with anti-PD-1 mAb showed better antitumor effects than either treatment alone. Our results suggest that EGFR inhibitors when used in conjunction with anti-PD-1 mAb could increase the efficacy of immunotherapy in lung adenocarcinomas.

Abstract PR12: The glycan CA19-9 promotes pancreatitis and pancreatic cancer in mice

Abstract Glycosylation alterations are indicative of tissue inflammation and neoplasia, but whether these alterations contribute to disease pathogenesis is largely unknown. To study the role of glycan changes in pancreatic disease, we inducibly expressed human fucosyltransferase 3 and b1,3-galactosyltransferase 5 in mice, reconstituting the glycan sialyl-Lewis a, also known as carbohydrate antigen 19-9 (CA19-9). Notably, CA19-9 expression in mice resulted in rapid and severe pancreatitis with hyperactivation of epidermal growth factor receptor (EGFR) signaling. Mechanistically, CA19-9 modification of the matricellular protein fibulin-3 increased its interaction with EGFR, and blockade of fibulin-3, EGFR, or CA19-9 prevented EGFR hyperactivation in organoids. CA19-9–mediated pancreatitis was reversible and could be suppressed with CA19-9 antibodies. CA19-9 also cooperated with the KrasG12D oncogene to produce aggressive pancreatic cancer. These findings implicate CA19-9 in the etiology of pancreatitis and pancreatic cancer and nominate CA19-9 as a therapeutic target. This abstract is also being presented as Poster C16. Citation Format: Dannielle Engle, Herve Tiriac, Keith Rivera, Arnaud Pommier, Sean Whalen, Tobiloba Oni, Brinda Alagesan, Eun Lee, Melissa Yao, Matthew Lucito, Benjamin Spielman, Kenneth Yu, Robert Grutzmann, Daniela Aust, Phyllis Gimotty, Katherine Pollard, Ralph Hruban, Michael Goggins, Christian Pilarsky, Young Park, Darryl Pappin, Michael A. Hollingsworth, David Tuveson. The glycan CA19-9 promotes pancreatitis and pancreatic cancer in mice [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr PR12.

Customisation of therapeutic strategy in metastatic colorectal cancer by use of liquid biopsies: Updated results of an observational study

Abstract Background Metastatic colorectal cancer (mCRC) affects 20% of patients diagnosed with colorectal malignancy and is a major cause of cancer-related death worldwide. Epidermal growth factor receptor (EGFR) blockade with monoclonal antibodies, in combination with chemotherapy, has been shown to benefit patients with RAS wild type tumours. Our project explores real-time assessment of mCRC mutational profile, by use of two methods of circulating tumour DNA (ctDNA) analysis, and its potential to better guide therapeutic decisions. Methods Baseline plasma samples were prospectively collected from 64 patients at diagnosis of mCRC and at disease progression. Analysis of KRAS and NRAS exons 2, 3 and 4 was performed with the highly sensitive BEAMing digital polymerase chain reaction (PCR) and next-generation sequencing (NGS). In a subgroup of patients, with baseline RAS mutations, mid-treatment liquid biopsies were performed, to assess the change in ctDNA RAS mutational load as response biomarker. Mutational status of matched tumour tissue, generated with a conventional PCR-based method or NGS, was prospectively recorded for all patients. Results Preliminary results of our study, presented at the EACR-ESMO Joint Conference on Liquid Biopsies, have shown detection of RAS mutations in the ctDNA from over 50% of patients, with a satisfactory plasma-tissue concordance. An update on these data, as well as on the predictive value of ctDNA RAS mutational load dynamics, will be presented. Disease progression data, in light of baseline RAS status, will also be revisited, as almost 20% of patients have progressed on first-line treatment. In addition, the concordance of BEAMing and NGS as liquid biopsy methods is to be studied in a subgroup of patients with available plasma samples. Conclusions The larger sample size and the maturity of this updated analysis further add on the value of our work, the results of which remain in line with the literature. Our study serves as a real-life example of the potential of liquid biopsies to detect RAS mutation status changes, allowing for precision-oncology therapeutic approaches in the continuum of care of metastatic colorectal cancer patients. Legal entity responsible for the study Department of Medical Oncology, University General Hospital of Ioannina. Funding Amgen, Hellenic Society of Medical Oncology (HeSMO) and Society for Study of Clonal Heterogeneity of Neoplasia (EMEKEN). Disclosure G. Pentheroudakis: Research grant / Funding (institution): Amgen. All other authors have declared no conflicts of interest.

Functional RNAi Screens Define Distinct Protein Kinase Vulnerabilities in EGFR-Dependent HNSCC Cell Lines.

The inhibitory epidermal growth factor receptor (EGFR) antibody, cetuximab, is an approved therapy for head and neck squamous cell carcinoma (HNSCC). Despite tumor response observed in some HNSCC patients, cetuximab alone or combined with radio- or chemotherapy fails to yield long-term control or cures. We hypothesize that a flexible receptor tyrosine kinase coactivation signaling network supports HNSCC survival in the setting of EGFR blockade, and that drugs disrupting this network will provide superior tumor control when combined with EGFR inhibitors. In this work, we submitted EGFR-dependent HNSCC cell lines to RNA interference-based functional genomics screens to identify, in an unbiased fashion, essential protein kinases for growth and survival as well as synthetic lethal targets for combined inhibition with EGFR antagonists. Mechanistic target of rapamycin kinase (MTOR) and erythroblastosis oncogene B (ERBB)3 were identified as high-ranking essential kinase hits in the HNSCC cell lines. MTOR dependency was confirmed by distinct short hairpin RNAs (shRNAs) and high sensitivity of the cell lines to AZD8055, whereas ERBB3 dependency was validated by shRNA-mediated silencing. Furthermore, a synthetic lethal kinome shRNA screen with a pan-ERBB inhibitor, AZD8931, identified multiple components of the extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase pathway, consistent with ERK reactivation and/or incomplete ERK pathway inhibition in response to EGFR inhibitor monotherapy. As validation, distinct mitogen-activated protein kinase kinase (MEK) inhibitors yielded synergistic growth inhibition when combined with the EGFR inhibitors, gefitinib and AZD8931. The findings identify ERBB3 and MTOR as important pharmacological vulnerabilities in HNSCC and support combining MEK and EGFR inhibitors to enhance clinical efficacy in HNSCC. SIGNIFICANCE STATEMENT: Many cancers are driven by nonmutated receptor tyrosine kinase coactivation networks that defy full inhibition with single targeted drugs. This study identifies erythroblastosis oncogene B (ERBB)3 as an essential protein kinase in epidermal growth factor receptor-dependent head and neck squamous cell cancer (HNSCC) cell lines and a synthetic lethal interaction with the extracellular signal-regulated kinase mitogen-activated protein kinase pathway that provides a rationale for combining pan-ERBB and mitogen-activated protein kinase inhibitors as a therapeutic approach in subsets of HNSCC.

Epidermal Growth Factor Receptor Blockade in Head and Neck Cancer: What Remains?

Epidermal Growth Factor Receptor Blockade in Head and Neck Cancer: What Remains?

A randomized, controlled phase II trial of neoadjuvant ado-trastuzumab emtansine, lapatinib, and nab-paclitaxel versus trastuzumab, pertuzumab, and paclitaxel in HER2-positive breast cancer (TEAL study)

BackgroundNeoadjuvant dual human epidermal growth factor receptor (HER2) blockade with trastuzumab and pertuzumab plus paclitaxel leads to an overall pathologic complete response (pCR) rate of 46%. Dual HER2 blockade with ado-trastuzumab emtansine (T-DM1) and lapatinib plus nab-paclitaxel has shown efficacy in patients with metastatic HER2-positive breast cancer. To test neoadjuvant effectiveness of this regimen, an open-label, multicenter, randomized, phase II trial was conducted comparing T-DM1, lapatinib, and nab-paclitaxel with trastuzumab, pertuzumab, and paclitaxel in patients with early-stage HER2-positive breast cancer.MethodsStratification by estrogen receptor (ER) status occurred prior to randomization. Patients in the experimental arm received 6 weeks of targeted therapies (T-DM1 and lapatinib) followed by T-DM1 every 3 weeks, lapatinib daily, and nab-paclitaxel weekly for 12 weeks. In the standard arm, patients received 6 weeks of trastuzumab and pertuzumab followed by trastuzumab weekly, pertuzumab every 3 weeks, and paclitaxel weekly for 12 weeks. The primary objective was to evaluate the proportion of patients with residual cancer burden (RCB) 0 or I. Key secondary objectives included pCR rate, safety, and change in tumor size at 6 weeks. Hypothesis-generating correlative assessments were also performed.ResultsThe 30 evaluable patients were well-balanced in patient and tumor characteristics. The proportion of patients with RCB 0 or I was higher in the experimental arm (100% vs. 62.5% in the standard arm, p = 0.0035). In the ER-positive subset, all patients in the experimental arm achieved RCB 0-I versus 25% in the standard arm (p = 0.0035). Adverse events were similar between the two arms.ConclusionIn early-stage HER2-positive breast cancer, the neoadjuvant treatment with T-DM1, lapatinib, and nab-paclitaxel was more effective than the standard treatment, particularly in the ER-positive cohort.Trial registrationClinicaltrials.gov NCT02073487, February 27, 2014.

Inhibition of EGFR-STAT3 attenuates cardiomyopathy in streptozotocin-induced type 1 diabetes.

Emerging evidence implicates elevated activity of STAT3 transcription factor in driving the development and progression of diabetic cardiomyopathy (DCM). We hypothesized that the fibrosis-promoting and hypertrophic actions of STAT3 are linked to the activation by epidermal growth factor receptor (EGFR). We tested this hypothesis by challenging cultured cardiomyocytes to high-concentration glucose and heart tissues of streptozotocin (STZ)-induced type 1 diabetic mice. Our results indicated that, in diabetic mice, the blockade of STAT3 or EGFR using selective inhibitors S3I-201 and erlotinib, respectively, abrogated the increased activating STAT3 phosphorylation and the induction of genes regulating fibrosis and hypertrophy in myocardial tissue. S3I-201 and erlotinib significantly reduced myocardial structural and functional deficits in diabetic mice. In cultured cardiomyocytes, high-concentration glucose induced EGFR-mediated STAT3 phosphorylation. We further showed that blockade of STAT3 or EGFR using selective inhibitors and siRNAs significantly reduced the increased expression of genes known to promote fibrosis and hypertrophy in cardiomyocytes. These results provide novel evidence that the EGFR-STAT3 signaling axis likely plays a crucial role in the development and progression of DCM.