EGFR-targeted Monoclonal Antibodies Research Articles

Molecular pathways and targeted therapies in head and neck cancers pathogenesis.

The substantial heterogeneity exhibited by head and neck cancer (HNC), encompassing diverse cellular origins, anatomical locations, and etiological contributors, combined with the prevalent late-stage diagnosis, poses significant challenges for clinical management. Genomic sequencing endeavors have revealed extensive alterations in key signaling pathways that regulate cellular proliferation and survival. Initiatives to engineer therapies targeting these dysregulated pathways are underway, with several candidate molecules progressing to clinical evaluation phases, including FDA approval for agents like the EGFR-targeting monoclonal antibody cetuximab for K-RAS wild-type, EGFR-mutant HNSCC treatment. Non-coding RNAs (ncRNAs), owing to their enhanced stability in biological fluids and their important roles in intracellular and intercellular signaling within HNC contexts, are now recognized as potent biomarkers for disease management, catalyzing further refined diagnostic and therapeutic strategies, edging closer to the personalized medicine desideratum. Enhanced comprehension of the genomic and immunological landscapes characteristic of HNC is anticipated to facilitate a more rigorous assessment of targeted therapies benefits and limitations, optimize their clinical deployment, and foster innovative advancements in treatment approaches. This review presents an update on the molecular mechanisms and mutational spectrum of HNC driving the oncogenesis of head and neck malignancies and explores their implications for advancing diagnostic methodologies and precision therapeutics.

Cetuximab inhibits colorectal cancer development through inactivating the Wnt/β-catenin pathway and modulating PLCB3 expression

Colorectal cancer (CRC) often necessitates cetuximab (an EGFR-targeting monoclonal antibody) for treatment. Despite its clinical utility, the specific operative mechanism of cetuximab remains elusive. This research investigated the influence of PLCB3, a potential CRC oncogene, on cetuximab treatment. We extracted differentially expressed genes from the GSE140973, the overlapping genes combined with 151 Wnt/β-Catenin signaling pathway-related genes were identified. Then, we conducted bioinformatics analysis to pinpoint the hub gene. Subsequently, we investigated the clinical expression characteristics of this hub gene, through cell experimental, scrutinized the impact of cetuximab and PLCB3 on CRC cellular progression. The study identified 26 overlapping genes. High expression of PLCB3, correlated with poorer prognosis. PLCB3 emerged as a significant oncogene associated with patient prognosis. In vitro tests revealed that cetuximab exerted a cytotoxic effect on CRC cells, with PLCB3 knockdown inhibiting CRC cell progression. Furthermore, cetuximab treatment led to a reduction in both β-catenin and PLCB3 expression, while simultaneously augmenting E-cadherin expression. These findings revealed PLCB3 promoted cetuximab inhibition on Wnt/β-catenin signaling. Finally, simultaneous application of cetuximab with a Wnt activator (IM12) and PLCB3 demonstrated inhibited CRC proliferation, migration, and invasion. The study emphasized the pivotal role of PLCB3 in CRC and its potential to enhance the efficacy of cetuximab treatment. Furthermore, cetuximab suppressed Wnt/β-catenin pathway to modulate PLCB3 expression, thus inhibiting colorectal cancer progression. This study offered fresh perspectives on cetuximab mechanism in CRC.

Abstract 4553: DXC004A, a novel EGFR antibody-tubulysin analog conjugate demonstrated potential to broaden therapeutic opportunities for non-small cell lung cancer

Abstract EGFR is a member of the epidermal growth factor receptor (HER) family, and the over-expression of EGFR plays an important role in the growth and progression of various tumors, including non-small cell lung cancer. Monoclonal EGFR antibodies, such as cetuximab and panitumumab, have proven efficacy in various types of cancer. However, treatment with the anti-EGFR agents can be associated with toxicities of the skin, nails, hair, and eyes. Nimotuzumab (Nimo) is the first humanized monoclonal antibody targeting EGFR and has been granted approval for use in squamous cell carcinoma of head and neck (SCCHN), glioma and nasopharyngeal cancer in different countries. In contrast to cetuximab, Nimotuzumab is distinguished by achieving higher or similar complete remission rate (CRR) or overall remission rate (ORR) of the primary tumor in clinical applications but much less toxicity, resulting in a better safety profile, which has been attributed to its about 10-fold lower affinity. Paclitaxel combined with cisplatin is the first-line chemotherapy regimen for non-small cell lung cancer. A phase 2 clinical trial has confirmed that Nimotuzumab combined with concurrent chemoradiation therapy (radiation concurrent with docetaxel and cisplatin, CCRT) was well tolerated for locally advanced squamous cell lung cancer. However, the combination strategy of Nimo-CCRT has only demonstrated similar OS and PFS to those in the CCRT group. DXC004A is an ADC drug targeting EGFR, in which a Nimotuzumab derivative and a Tubulysin B analog is conjugated by a functional linker. DXC004A is in phase I clinical trial and has demonstrated clinical activity in advanced non-small cell lung cancers and good tolerability. In vitro and in vivo results had confirmed that DXC004A monotherapy had better anti-tumor activity than the combination of Nimotuzumab and Tubulysin analog in HCC827 cell lines with high EGFR expression. Meanwhile, a single injection of low-dose DXC004 (2.5 mg/kg) in HCC827 xenograft model showed very good durable anti-tumor effect. Moreover, the combination of DXC004A with Cisplatin exhibited significantly better activities than that of Nimo-CCRT combination, DXC004A or cisplatin alone, in vitro and in vivo, which might solve the predicament of poor efficacy of Nimo-CCRT combination therapy. This synergy results suggested that DXC004A plus cisplatin would possibly be a new adjuvant therapy for non-small cell lung cancer in further clinical studies. Citation Format: Xiaobo Cai, Min Cao, Huihui Guo, Qingliang Yang, Yongxiang Chen, Xiangfei Kong, Yong Du, Zhicang Ye, Zhixiang Guo, Lingli Zhang, Lu Bai, Junxiang Jia, Yunxia Zheng, Wei Zheng, Jun Zheng, Wenjun Li, Yuanyuan Huang, Zhongliang Fan, Binbin Chen, Meng Dai, Robert Y. Zhao. DXC004A, a novel EGFR antibody-tubulysin analog conjugate demonstrated potential to broaden therapeutic opportunities for non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4553.

Biomarkers for monoclonal antibody targeting EGFR in NSCLC: Challenges, current status, and future perspectives

Targeting EGFR has a long history in the treatment of non-small cell lung cancer (NSCLC). It was around the 2000s that it was reported that EGFR protein expression increased with bronchial dysplasia in high-risk smokers and patients with lung cancer. However, EGFR inhibitors were not effective in unselected patients with advanced NSCLC. After the identification of sensitizing EGFR mutations, tyrosine kinase inhibitors became the cornerstone of treatment for patients with EGFR-mutated NSCLC. However, other drugs were developed to target EGFR in the EGFR-wild type population, such as monoclonal antibodies. Cetuximab is an anti-EGFR monoclonal antibody, and has been a focus over the past two decades. Though not approved in NSCLC due to marginal and inconsistent effects in phase 3 trials, research aimed to discover biomarkers to identify a subgroup of the population that might benefit. This includes a composite score that evaluates histology, immunohistochemistry, and gene copy amplification. This article reviews the history of the development and discontinuation of monoclonal antibodies in NSCLC and discusses the role of biomarkers in the treatment of advanced EGFR-wild type NSCLC.

EMab-300 Detects Mouse Epidermal Growth Factor Receptor-Expressing Cancer Cell Lines in Flow Cytometry.

Epidermal Growth Factor Receptor (EGFR) overexpression or its mutation mediates the sustaining proliferative signaling, which is an important hallmark of cancer. Human EGFR-targeting monoclonal antibody (mAb) therapy such as cetuximab has been approved for clinical use in patients with colorectal cancers and head and neck squamous cell carcinomas. A reliable preclinical mouse model is essential to further develop the mAb therapy against EGFR. Therefore, sensitive mAbs against mouse EGFR (mEGFR) should be established. In this study, we developed a specific and sensitive mAb for mEGFR using the Cell-Based Immunization and Screening (CBIS) method. The established anti-mEGFR mAb, EMab-300 (rat IgG1, kappa), reacted with mEGFR-overexpressed Chinese hamster ovary-K1 (CHO/mEGFR) and endogenously mEGFR-expressed cell lines, including NMuMG (a mouse mammary gland epithelial cell) and Lewis lung carcinoma cells, using flow cytometry. The kinetic analysis using flow cytometry indicated that the KD of EMab-300 for CHO/mEGFR and NMuMG was 4.3 × 10-8 M and 1.9 × 10-8 M, respectively. These results indicated that EMab-300 applies to the detection of mEGFR using flow cytometry and may be useful to obtain the proof of concept in preclinical studies.

Feasibility of [18F]FSPG PET for Early Response Assessment to Combined Blockade of EGFR and Glutamine Metabolism in Wild-Type KRAS Colorectal Cancer.

Early response assessment is critical for personalizing cancer therapy. Emerging therapeutic regimens with encouraging results in the wild-type (WT) KRAS colorectal cancer (CRC) setting include inhibitors of epidermal growth factor receptor (EGFR) and glutaminolysis. Towards predicting clinical outcome, this preclinical study evaluated non-invasive positron emission tomography (PET) with (4S)-4-(3-[18F]fluoropropyl)-L-glutamic acid ([18F]FSPG) in treatment-sensitive and treatment-resistant WT KRAS CRC patient-derived xenografts (PDXs). Tumor-bearing mice were imaged with [18F]FSPG PET before and one week following the initiation of treatment with either EGFR-targeted monoclonal antibody (mAb) therapy, glutaminase inhibitor therapy, or the combination. Imaging was correlated with tumor volume and histology. In PDX that responded to therapy, [18F]FSPG PET was significantly decreased from baseline at 1-week post-therapy, prior to changes in tumor volume. In contrast, [18F]FSPG PET was not decreased in non-responding PDX. These data suggest that [18F]FSPG PET may serve as an early metric of response to EGFR and glutaminase inhibition in the WT KRAS CRC setting.

Expression of EGFR and conformational forms of EGFR in malignant pleural mesothelioma and its impact on survival

AimConformational forms of the epidermal growth factor receptor (EGFR) are pro‐tumorigenic. The prevalence and impact of conformational forms of EGFR in malignant mesothelioma (MM) is unknown. We investigated expression of EGFR and conformational forms of EGFR by immunohistochemistry using EGFR-targeting monoclonal antibodies (mAb). In addition, EGFR gene amplification was investigated by fluorescent in-situ hybridization (FISH). Findings were correlated with survival. MethodsPatients treated between 1988 and 2014 were identified from the thoracic surgery database of the Austin Hospital, Melbourne, Australia. Tissue microarrays (TMAs) were constructed, subjected to wild type (wt) EGFR IHC staining and FISH analysis. Conformational and mutation forms of EGFR were detected by IHC using mAb806, and LMH-151 which detects EGFRVIII. `H-scores` were derived and EGFR expression correlated with survival by Kaplan-Meier and log rank analysis. ResultsWtEGFR expression was seen in 93 % (299/321) of cases with overexpression (defined as an H-score ≥200) seen in more than half of cases (64 %). EGFR overexpression in MM was seen more commonly in the epithelioid subtype. EGFR overexpression was not associated with true EGFR amplification, although multiple copies were appreciated in samples with polysomy. EGFR expression did not correlate with survival. A conformational form of EGFR associated with EGFR dysregulation was found in 8.2 % of cases, and patients with these tumors had a trend towards a poorer outcome. No cases of the EGFRVIII mutation were identified. ConclusionMM consistently demonstrated high expression of EGFR, with a subset of tumors showing conformational EGFR forms consistent with EGFR dysregulation, but withoutEGFR amplification or EGFR VIII mutation. wtEGFR expression did not influence survival. The impact of EGFR conformation on survival warrants further investigation.

Understanding the Monoclonal Antibody Involvement in Targeting the Activation of Tumor Suppressor Genes.

Monoclonal antibodies (mAbs) have always provided outstanding therapeutic arsenal in the treatment of cancer, be it hematological malignancies or solid tumors. Monoclonal antibodies mediated targeting of cancer genes in general and tumor-suppressor genes, in particular, have appreciably allowed the possibilities of trafficking these antibodies to specific tumor mechanisms and aim for the pin-point maneuvered tumor treatment strategies. The conventional cancer treatment options are associated with enormous limitations like drug resistance, acute and pan-toxic side effects and collateral damage to other unrelated cells and organs. Therefore, monoclonal antibody-mediated treatments have some special advantages of specific targeting of cancer-related genes and minimizing the off-target side effects. A large number of monoclonal antibody-mediated treatment regimen viz. use of immunoconjugates, clinically targeting TGFβ with pan-TGFβ monoclonal antibodies, p53 by its monoclonal antibodies and EGFRtargeted monoclonal antibodies, etc. have been observed in the recent past. In this review, the authors have discussed some of the significant advances in the context of targeting tumor suppressor genes with monoclonal antibodies. Approximately 250 articles were scanned from research databases like PubMed central, Europe PubMed Central and google scholar up to the date of inception, and relevant reports on monoclonal antibody-mediated targeting of cancer genes were selected. mAb mediated targeting of tumor suppressor genes is a recent grey paradigm, which has not been explored up to its maximum potential. Therefore, this review will be of appreciable significance that it will boost further in-depth understanding of various aspects of mAb arbitrated cancer targeting and will warrant and promote further rigorous research initiatives in this regard. The authors expect that this review will acquaint the readers with the current status regarding the recent progress in the domain of mAbs and their employability and targetability towards tumor suppressor genes in anti-cancer therapeutics.

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.

DRES-12. QUANTIFYING INDIVIDUALIZED ABT-414 SENSITIVITY AND BLOOD-BRAIN BARRIER PENETRANCE FROM SERIAL IMAGING OF PATIENT-DERIVED XENOGRAFTS MODELS OF GLIOBLASTOMA

Abstract INTRODUCTION Glioblastoma (GBM) is an aggressive primary brain tumor, known for its poor prognosis. Due to its diffuse invasiveness into normal-appearing brain, localized treatments such as surgical resection and radiotherapy are typically supplemented with chemotherapy. However, to reach invading tumor cells, such antineoplastic drugs must cross the blood-brain barrier (BBB). That is, while angiogenesis induces BBB breakdown in dense tumor regions, the BBB remains rather intact for invading GBM cells. As a result, it is unclear whether BBB-impermeable drugs are delivered at a sufficient level to be effective. METHODS In order to study heterogeneity in BBB breakdown, experiments were conducted using both flank and intracranial patient-derived xenografts (PDXs) treated with the EGFR-targeted monoclonal antibody drug conjugate, depatuxizumab mafodotin (ABT-414). Time-series bioluminescence imaging (BLI) data was used to develop a differential equation model of tumor growth for three PDX cell lines. Data from untreated PDXs, both in flank and intracranially, were used to parameterize tumor proliferation rates. Flank PDX data were used to parameterize individual sensitivity to ABT-414, whereas intracranial PDX data were used to determine the proportion of drug exposed to the tumor. RESULTS Each PDX line differed in response to the study drug ABT-414. As expected, such heterogeneous responses can primarily be attributed to differences in both drug sensitivity and the proportion of drug that reached the tumor. Notably, the estimated proportion of drug that reached the tumor was highest in the PDX line with the longest survival times, despite also having higher estimates of resistance. This suggests that PDXs with greater overall BBB breakdown may respond better to this agent. CONCLUSIONS Although more cell lines are needed to validate our approach, parameterizing this model for PDXs gives valuable insight into the extent of BBB breakdown in patient GBMs and may aid in determining optimal therapies for individual patients.

Targeting EGFR pathway in metastatic colorectal cancer- tumour heterogeniety and convergent evolution.

Despite significant progress in management of metastatic colorectal cancer (mCRC) pertaining to better screening procedures and amelioration of the therapeutic armamentarium with targeted therapies, prognosis remains poor. Targeting epidermal growth factor receptor (EGFR) has been of particular interest owing to favourable efficacy benefits demonstrated by monoclonal antibodies (cetuximab and panitumumab) in various clinical settings and development of predictive biomarkers informing treatment decisions respectively. In spite of optimal patient selection based on RAS mutation status, primary and secondary resistance to monoclonal antibodies is higher than desired. Further research into predictive biomarkers is therefore essential, but has, to date, been conducted with considerable limitations. Whilst molecular heterogeneity has been demonstrated by several studies in mCRC, for incomprehensible reasons, multiple resistant genetic alterations that emerge under the selective pressure of EGFR-targeted therapies are somehow able to influence the biological and clinical behaviour of cancer cells, despite being detectable at extremely low frequencies. Intriguingly, these subclonal events largely seem to converge on RAS/RAF/MAPK pathway in patients treated with EGFR-targeted monoclonal antibodies. This review describes the clinical and biological evolution and development of EGFR targeted therapies in mCRC, the challenges in the presence of molecular complexities, the role of cell free (cf)-DNA and future strategies that could lead to further optimal discovery of clinically meaningful biomarkers and application of precision medicine.

Abstract 559: Preclinical characterization of the bispecific EGFR/CD16A innate immune cell engager AFM24 for the treatment of EGFR-expressing solid tumors

Abstract Affimed has engineered AFM24 based on its Redirected Optimized Cell Killing (ROCK®) platform to redirect innate immune cells to EGFR-positive tumor cells with the potential for activation of a broad anti-tumor immune response. This fully human tetravalent bispecific EGFR and CD16A binding antibody was designed for the treatment of EGFR-expressing malignancies with the potential to overcome the resistance to other EGFR-targeting agents and offering a better safety profile. The efficacy of current standard of care (SOC), including EGFR-targeting monoclonal antibodies (mAbs) and tyrosine kinase inhibitors (TKIs), depends on intrinsic or acquired mutations that impact EGFR signal transduction. AFM24 exerts a mutation-independent mechanism of action (MOA), redirecting innate immunity via NK cells or macrophages to EGFR-positive tumor cells. PK analyses of AFM24 revealed a half-life of ~14 days in mice and ~5 days in cynomolgus monkeys. Using radioactively labeled AFM24 in mice, tumor-specific accumulation in subcutaneous human tumors was observed. While binding to CD16A by classical mAbs has low affinity and is further impaired by competition with serum IgG, no substantial changes in the very high binding affinity of AFM24 to NK cells were observed in the presence of IgG. Anti-tumor efficacy has been shown in in vitro cytotoxicity assays and in in vivo tumor models. Due to its MOA, AFM24 was also active against tumor cell lines expressing mutated Ras in in vitro assays. Antibody-dependent cellular phagocytosis (ADCP) of tumor cell lines expressing high levels of EGFR was comparable between AFM24 and classical or Fc-enhanced mAbs, but ADCP of tumor cells with lower EGFR expression mediated by AFM24 was more pronounced. Owing to their MOA of blocking EGFR-induced signaling, the therapeutic use of current SOC is associated with severe side effects such as skin toxicity, potentially limiting its use due to dosing interruptions and/or treatment termination. AFM24 is designed to exhibit a reduced potential to inhibit EGFR signaling, aiming for an improved safety profile. In a 4-week toxicology study in cynomolgus monkeys, no skin or organ toxicity was observed at AFM24 doses between 24 and 75 mg/kg i.v. once weekly. In toxicology studies investigating EGFR-targeting mAbs, e.g. cetuximab, with a similar experimental design, severe toxicities have been observed at those dosages. In summary, AFM24 is a novel, differentiated bispecific innate immune cell engager binding to EGFR and CD16A, thereby redirecting tumor cell killing by NK cells and macrophages to EGFR-expressing tumors. Its preclinical characterization described here, encourages AFM24’s development for the treatment of EGFR-expressing tumors with the potential to overcome resistance to current SOC while conferring a favorable safety profile. IND-enabling preclinical development is ongoing. Citation Format: Michael Kluge, Uwe Reusch, Stefan Knackmuss, Torsten Haneke, Susanne Wingert, Michael Damrat, Michael Tesar, Martin Treder. Preclinical characterization of the bispecific EGFR/CD16A innate immune cell engager AFM24 for the treatment of EGFR-expressing solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 559.

Beyond EGFR Targeting in SCCHN: Angiogenesis, PI3K, and Other Molecular Targets.

Although the molecular landscape of squamous cell carcinoma of the head and neck (SCCHN) has been largely deciphered, only one targeted therapy has been approved to date without any molecular selection, namely cetuximab. Cetuximab is a monoclonal antibody targeting EGFR. It has been shown to improve overall survival in the locally advanced setting in combination with radiotherapy and the recurrent and/or metastatic setting in combination with a platinum compound and 5FU. Beside EGFR targeting agents, antiangiogenic agents have been shown to produce antitumor activity but were associated with substantial toxicity. Buparlisib that targets PI3K was also shown to improve survival in combination with paclitaxel in an unselected patient population. Several other targeted therapies have been developed in SCCHN, most of time in all comers, potentially explaining the limited efficacy reported with them. The recent emergence of clinical trials of targeted therapies in enriched patient populations and precision medicine trials such as umbrella trials might boost the clinical development of targeted therapy in SCCHN.

Synthesis and preclinical investigation of 99mTc-p-SCN-Bzl-DTPA-cetuximab for targeting EGFR using head and neck squamous cell carcinoma (HNSCC) xenografts.

To assess the preclinical potential of technetium-99m labelled conjugated para-isothiocyanato-benzyl diethylene triamine penta-acetic acid cetuximab (99mTc-p-SCN-Bzl-DTPA cetuximab) for imaging EGFR in HNSCC mice and rabbits xenografts. Cetuximab, a chimeric monoclonal antibody targeting EGFR, was conjugated with p-SCN-Bzl-DTPA followed by labelling with 99mTc. The labelled conjugate was evaluated for in vitro stability in L-cysteine at 37°C. The 99mTc-p-SCN-Bzl-DTPA cetuximab was also investigated for immunoreactivity, internationalization kinetics, dose escalation (up to 300µg) and biodistribution in HNSCC mice xenograft. The suitability of labelled moiety as a specific EGFR radio-tracer was assessed in HNSCC rabbit xenograft. 99mTc-p-SCN-Bzl-DTPA cetuximab exhibited more than 98% radiochemical purity at room temperature. In excess L-cysteine, it showed a stable behaviour at 37°C up to 4h p.l. The labelled conjugate was internalized in vitro in FaDu tumor cells up to 19.55%. Significantly higher uptake in tumor (at 10µg; 34.75 ± 0.38% ID/g: pi) was seen in HNSCC mice xenograft with dose escalation assay from 1 to 300µg/mouse. Blocking of EGFR with excess cetuximab consequently decreased the uptake of tumor up to 6.80 ± 1.25%. SPECT images of rabbit xenograft confirmed increase in tumor to background ratio after 4h pi and validated its potential in preclinical trial as a specific FaDu tumor tracer. Our in vitro and in vivo preclinical findings indicate that the 99mTc-p-SCN-Bzl-DTPA cetuximab prepared at optimal dose of cetuximab could become a useful tool for EGFR imaging in HNSCC using SPECT.

Low intensity focused ultrasound (LIFU) triggered drug release from cetuximab-conjugated phase-changeable nanoparticles for precision theranostics against anaplastic thyroid carcinoma.

Currently, multifunctional nanotechnology is strongly expected to improve the prospect of treatment and diagnosis. In this study, we synthesized epidermal growth factor (EGFR)-targeted phase-changeable polymer nanoparticles (C-HPNs) loaded with two drugs (C225 and 10-HCPT) for specific tumor targeting, synergistic chemotherapy, and ultrasound imaging under low-intensity focused ultrasound (LIFU). Cetuximab (C225), an EGFR-targeted monoclonal antibody, was conjugated on the surface of the nanoparticles, leading to a significantly high binding affinity to EGFR-overexpressing anaplastic thyroid C643 cells both in vitro and in vivo. As expected, an increase of more than 3- to 4-fold in the release rates of 10-HCPT was observed after LIFU irradiation in vitro, demonstrating that LIFU could enhance the release of drugs from the nanoparticles. Combined treatment with C-HPNs and LIFU showed excellent inhibition of cell proliferation in vitro, as well as a remarkable therapeutic effect in vivo. Moreover, the combined treatment simultaneously enhanced ultrasound imaging by LIFU-induced acoustic droplet vaporization (ADV). In conclusion, C225-modified and phase-changeable nanoparticles combined with LIFU exhibited great promise for concurrent targeted ultrasound molecular imaging and effective synergistic antitumor therapy.

Abstract 2600: Resistance biomarkers in patients with head and neck squamous cell carcinoma treated with cetuximab

Abstract BACKGROUND: Cetuximab, a monoclonal antibody targeting EGFR, improves overall survival in the locally advanced setting in combination with radiotherapy and in first-line recurrent setting in combination with chemotherapy in HNSCC patients. No predictive biomarker of efficacy of cetuximab in these settings. We aimed at identifying biomarkers of sensitivity/resistance to cetuximab. PATIENTS AND METHODS: HNSCC patients treated with cetuximab at Institut Curie, for which complete clinicopathological data and formalin-fixed, paraffin-embedded (FFPE) tumor tissue were available and collected before cetuximab treatment, were included in this retrospective study. Immunohistochemistry analyses of PTEN and EGFR were performed to assess expression levels. PIK3CA and KRAS mutations were analyzed using high resolution melting (HRM) and Sanger sequencing. The predictive value of these alterations on progression-free survival (PFS) was evaluated. RESULTS: PIK3CA and KRAS/HRAS mutations were associated with poor PFS in HNSCC patients treated with cetuximab in first-line recurrence setting but not in patients treated with cetuximab in combination with radiotherapy. PTEN loss of expression had a negative prognostic impact in HNSCC patients treated with cetuximab and radiotherapy, while EGFR high expression was not found to be a sensitivity biomarker for cetuximab in our patient population. CONCLUSIONS: PIK3CA and RAS mutations were resistance biomarkers of cetuximab in first-line recurrent setting, whereas PTEN loss was a resistance biomarker of cetuximab when given in combination with radiotherapy. Citation Format: Maud Kamal, Olivia Leblanc, Sophie Vacher, Charlotte Lecerf, Emmanuelle Jeannot, Jerzy Klijanienko, Frederique Berger, Caroline Hoffmann, Valentin Calugaru, Nathalie Badois, Anne Chilles, Maria Lesnik, Samar Krhili, Thomas Jouffroy, Ivan Bieche, Christophe Le Tourneau. Resistance biomarkers in patients with head and neck squamous cell carcinoma treated with cetuximab [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2600.

Abstract 2786: Pharmacokinetics and in vitro/in vivo characterization of high-affinity bispecific EGFR/CD16A NK cell engagers for the treatment of EGFR-expressing tumors

Abstract The epidermal growth factor receptor (EGFR) is a validated target for the treatment of several solid tumor types. Current EGFR-targeting monoclonal antibodies (mAbs) and tyrosine kinase inhibitors function mainly through blocking of signal-transduction. Moreover, treatment with these agents is dependent on the receptor's mutational status which may cause treatment resistance in a large number of patients. In addition, EGFR-targeting therapies have been associated with side effects considered to impact prescription rates, in particular in the U.S. A natural killer (NK) cell-based EGFR-targeting approach has the potential to widen the therapeutic window and overcome intrinsic and acquired resistance. Therefore, it offers a promising and well differentiated therapeutic option. We describe the engineering of different bispecific NK cell engagers designed to redirect NK cell-mediated killing to EGFR-positive tumors. Different bispecific EGFR/CD16A antibody constructs targeting human and cynomolgus EGFR and CD16A were designed using novel human Fv antibody binding domains from a toolbox of formats. The Fv domains were evaluated in terms of their pharmacokinetic (PK) properties. Furthermore, the antibody constructs were characterized in antigen and cell binding assays, as well as in in vitro cytotoxicity assays against tumor cell lines expressing Raswt or mutated Ras. PK parameters were determined in CD1 mice and in vivo efficacy of selected antibodies was investigated in an A-431 tumor model in humanized mice. We generated antibody constructs with varying half-lives, including antibodies with a PK profile which allows for dosing comparable to IgG-based antibodies, while aiming at an improved safety profile compared to other EGFR-targeting therapies. Different high affinity tetravalent, bispecific antibodies binding to CD16A and the extracellular domain of EGFR were characterized. While binding to CD16A of classical mAbs is impaired by serum IgG, no substantial changes in binding affinity of our constructs to NK cells were observed. The antibodies showed superior potency and efficacy compared to mAbs or Fc-enhanced antibodies when tested in cytotoxicity assays. In vivo efficacy of selected antibodies was demonstrated in an A-431 tumor model in humanized mice. We have successfully designed and characterized several novel, highly potent and differentiated tetravalent bispecific antibody constructs to redirect NK cell-mediated cell killing to EGFR-positive tumor cells. These drug candidates are suitable for the treatment of EGFR-expressing malignancies with the potential to overcome resistance to other EGFR-targeting agents and offering a potentially improved safety profile. These candidates are currently in development as monotherapy and are also explored in combination with immune activating agents. Citation Format: Michael Kluge, Michael Tesar, Uwe Reusch, Stefan Knackmuss, Torsten Haneke, Kristina Ellwanger, Ivica Fucek, Thomas Mueller, Ute Schniegler-Mattox, Martin Treder. Pharmacokinetics and in vitro/in vivo characterization of high-affinity bispecific EGFR/CD16A NK cell engagers for the treatment of EGFR-expressing tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2786.

Combinations of Bevacizumab and Erlotinib Show Activity in Colorectal Cancer Independent of RAS Status.

Purpose: There is extensive cross-talk between VEGF- and EGFR-pathway signaling in colorectal cancer. However, combinations of VEGF- and EGFR-targeted monoclonal antibodies (mAb) show disappointing activity, in particular for patients with mutant RAS Previous results show that tyrosine kinase inhibitors (TKI) can be active in colorectal cancer models resistant to mAbs. This prompted us to examine whether the activity of bevacizumab can be increased by combination with erlotinib.Experimental Design: The antitumor activity of bevacizumab, erlotinib, and their combination was determined in colorectal cancer models with different RAS status and bevacizumab sensitivity. EGFR/VEGF pathway activation was characterized by immunohistochemistry, Western blot, and ELISA assays. The influence of cetuximab and erlotinib on EGF-mediated migration and the EGFR-EGF ligand feedback loop was established in colorectal cancer cell lines with different RAS status.Results: The addition of erlotinib increased bevacizumab activity in all models independent of RAS status. Bevacizumab exposure was accompanied by marked EGFR activation in tumor cells as well as in tumor-associated endothelial cells (TECs) and resulted in strong accumulation of intracellular EGFR, which could be attenuated by erlotinib. In cellular models, erlotinib was able to attenuate EGF-mediated functions in all cell lines independent of RAS status while cetuximab only showed activity in RAS wild-type cells.Conclusions: These results should provide a molecular framework to better understand the increased activity of the bevacizumab-erlotinib combination, compared with bevacizumab alone, in the GERCOR DREAM phase III clinical trial. Differential activity of mAbs and TKIs targeting the same signaling pathway is likely applicable for other tumor types. Clin Cancer Res; 24(11); 2548-58. ©2018 AACR.

EGFR Gene Copy Number by FISH May Predict Outcome of Necitumumab in Squamous Lung Carcinomas: Analysis from the SQUIRE Study.

Necitumumab is a monoclonal antibody targeting EGFR. In the SQUIRE trial, the addition of necitumumab to chemotherapy for squamous cell lung cancer significantly improved overall survival (OS) (hazard ratio [HR]= 0.84); in a post hoc analysis, EGFR copy number gain determined by fluorescence in situ hybridization (FISH) showed a trend toward improved OS (HR= 0.70) and progression-free survival (PFS) (HR= 0.71) with the addition of necitumumab. We present the analysis of granular EGFR FISH data from SQUIRE to examine the potential predictive role of high polysomy and gene amplification, as both were included in the FISH-positive category. Available specimens from SQUIRE underwent FISH analysis in a central laboratory, and each sample was evaluated by using the Colorado EGFR scoring criteria. Thecorrelation of granular FISH parameters with clinical outcomes was assessed. Samples were available for 557 of 1093 patients; 208 patients (37.3%) were FISH-positive, including 167 (30.0%) with high polysomy and 41 (7.4%) with gene amplification. In patients with high polysomy, the addition of necitumumab resulted in a statistically significant increase in PFS (6.08 versus 5.13 months [p= 0.044]) and nonstatistically significant increase in OS (12.6 versus 9.5 months [p= 0.133]); among patients with gene amplification, the addition of necitumumab did not significantly improve PFS (7.4 versus 5.6 months; [p= 0.334]) but did improve OS (14.8 versus 7.6 months; [p = 0.033]). EGFR copy number gain by FISH might have arole as a predictive biomarker for necitumumab in squamous cell lung cancer. In our opinion, these data encourage further studies to prospectively evaluate this potential biomarker.

Comparison of Ras/Raf/MAPK signaling pathway in primary tumour and lymph node metastases – A report on an experimental study of two colorectal cancer cell lines (SW480 and SW620) and tissue samples

Aim: To compare the presence of mutations in essential genes of CRC pathogenesis pathway between tissues derived from the primary tumour site and lymph node metastases. Introduction: Colorectal cancer (CRC) remains the third most commonly diagnosed malignancy worldwide and a leading cause of cancer - related death. One of the pivotal pathways leading to CRC development is Ras/Raf/MAPK which is regulated by the receptor for the EGF. Mutations in these genes predict lack of response to EGFR-targeting monoclonal antibodies. However it is a common practice to assess only the primary tumour site, while mutations in metastasis may also affect the response to treatment. Methods: The study was conducted on 10 patient-derived tissue samples and two ATCC human CRC cell lines obtained from the same individual: SW480 (primary tumour) and SW620 (lymph node metastasis). Cell lines were cultured according to the protocol. Genomic DNA and RNA were isolated, and PCR and RT-PCR were conducted. Primers for PCR included the following fragments: KRAS (exons 2,3,4), NRAS (exons 2,3,4), BRAF (exon 15); and for RT-PCR: KRAS, NRAS, BRAF and EGFR. Restriction enzymes were used. Proteins were extracted, purified and Western-Blot (RAS, RAF, MAPK) was performed. Results: For SW480 we detected a mutation in exon 3 of NRAS gene, whereas SW620 presented a wild type. The level of Ras protein remained the same. Raf protein expression was abundant in the primary tumour site as compared to the lymph node metastasis, whereas MAPK protein presented the opposite level of expression. Conclusion: The analysis of Ras-Raf-MAPK pathway may suggest that along with the tumour progression, the dominating signal is located at deeper levels of signaling pathway. Due to existing differences in key molecular points between the primary tumour and its metastases, in the era of targeted therapy, pre-treatment assessment of both sites has a potential to become a standard of care.1,2