MetMAb, the one-armed 5D5 anti-c-Met antibody, inhibits orthotopic pancreatic tumor growth and improves survival

c-MET and the immunological landscape of cancer: novel therapeutic strategies for enhanced anti-tumor immunity

Cellular mesenchymal-epithelial transition factor (c-MET), also known as hepatocyte growth factor receptor (HGFR), is a crucial receptor tyrosine kinase implicated in various solid tumors, including lung, breast, and liver cancers. The concomitant expression of c-MET and PD-L1 in tumors, such as hepatocellular carcinoma, highlights their prognostic significance and connection to therapeutic resistance. Cancer-associated fibroblasts and mesenchymal stromal cells produce hepatocyte growth factor (HGF), activating c-MET signaling in tumor cells and myeloid-derived suppressor cells (MDSC). This activation leads to metabolic reprogramming and increased activity of enzymes like glutaminase (GLS), indoleamine 2,3-dioxygenase (IDO), and arginase 1 (ARG1), depleting essential amino acids in the tumor microenvironment that are vital for effector immune cell function. This review highlights the interplay between tumor cells and myeloid-derived suppressor cells (MDSCs) that create an immunosuppressive environment while providing targets for c-MET-focused immunotherapy. It emphasizes the clinical implications of c-MET inhibition on the behavior of immune cells such as neutrophils, macrophages, T cells, and NK cells. It explores the potential of c-MET antagonism combined with immunotherapeutic strategies to enhance cancer treatment paradigms. This review also discusses the innovative cancer immunotherapies targeting c-MET, including chimeric antigen receptor (CAR) therapies, monoclonal antibodies, and antibody-drug conjugates, while encouraging the development of a comprehensive strategy that simultaneously tackles immune evasion and enhances anti-tumor efficacy further to improve the clinical prognoses for patients with c-MET-positive malignancies. Despite the challenges and variability in efficacy across different cancer subtypes, continued research into the molecular mechanisms and the development of innovative therapeutic strategies will be crucial.

Progress of antibody-drug conjugates (ADCs) targeting c-Met in cancer therapy; insights from clinical and preclinical studies

The cell-surface receptor tyrosine kinase c-mesenchymal-epithelial transition factor (c-Met) is overexpressed in a wide range of solid tumors, making it an appropriate target antigen for the development of anticancer therapeutics. Various antitumor c-Met-targeting therapies (including monoclonal antibodies [mAbs] and tyrosine kinases) have been developed for the treatment of c-Met-overexpressing tumors, most of which have so far failed to enter the clinic because of their efficacy and complications. Antibody-drug conjugates (ADCs), a new emerging class of cancer therapeutic agents that harness the target specificity of mAbs to deliver highly potent small molecules to the tumor with the minimal damage to normal cells, could be an attractive therapeutic approach to circumvent these limitations in patients with c-Met-overexpressing tumors. Of great note, there are currently nine c-Met-targeting ADCs being examined in different phases of clinical studies as well as eight preclinical studies for treating various solid tumors. The purpose of this study is to present a broad overview of clinical- and preclinical-stage c-Met-targeting ADCs.

AHNAK2 Promotes the Progression of Pancreatic Ductal Adenocarcinoma by Maintaining the Stability of c-MET

Purpose

Pancreatic ductal adenocarcinoma (PDAC) is extremely malignant and rapidly progresses. The overall response rate of PDAC to current treatment methods is still unsatisfactory. Thus, identifying novel targets and clarifying the underlying mechanisms associated with PDAC progression may potentially offer additional treatment strategies. AHNAK2 is aberrantly expressed in a variety of tumors and exerts pro-tumorigenic effects. However, the biological role of AHNAK2 in PDAC remains poorly understood.

Methods

The expression of AHNAK2 in PDAC and paired non-tumor tissues was detected by immunohistochemistry (IHC) and quantitative real-time polymerase chain reaction (qRT-PCR). Lentivirus knockdown was performed to investigate the impact of AHNAK2 on the biological function of pancreatic cancer cells. The subcutaneous cell-derived xenograft (CDX) model and the KPC spontaneous mouse model with AHNAK2 silencing were used to observe the effects of AHNAK2 on tumor growth and prognosis. The expression of c-MET at protein level in response to HGF treatment was assessed using western blot.

Results

Our results demonstrated that AHNAK2 was highly expressed in PDAC clinical samples and associated with poor prognosis. Knockdown of AHNAK2 significantly inhibited the proliferation, migration, and invasion of pancreatic cancer cells. AHNAK2 knockdown or knockout resulted in tumor growth suppression and prolonged survival in mice with PDAC. In addition, AHNAK2 and c-MET expression levels showed a significant positive correlation at the post-transcriptional level. Mechanistically, AHNAK2 promoted tumor progression by preventing c-MET degradation and persistently activating the HGF/c-MET signaling pathway.

Conclusion

Overall, our study revealed that AHNAK2 plays an important role in PDAC progression by modulating the c-MET signaling pathway, and targeting AHNAK2 may be an effective therapeutic strategy for PDAC.

PP2A complex disruptor SET prompts widespread hypertranscription of growth-essential genes in the pancreatic cancer cells

Hyperactivation of the oncogenic transcription reflects the epigenetic plasticity of the cancer cells. Su(var)3-9, enhancer of zeste, Trithorax (SET) was described as a nuclear factor that stimulated transcription from the chromatin template. However, the mechanisms of SET-dependent transcription are unknown. Here, we found that overexpression of SET and CDK9 induced very similar transcriptome signatures in multiple cancer cell lines. SET localized in the transcription start site (TSS)-proximal regions and supported the RNA transcription. SET specifically bound the PP2A-C subunit and induced PP2A-A subunit repulsion from the C subunit, which indicated the role of SET as a PP2A-A/C complex disruptor in the TSS-proximal regions. Through blocking PP2A activity, SET assisted CDK9 to maintain Pol II CTD phosphorylation and activated mRNA transcription. Our findings position SET as a key factor that modulates chromatin PP2A activity, promoting the oncogenic transcription in the pancreatic cancer.

Phase I Trial of Autologous RNA-electroporated cMET-directed CAR T Cells Administered Intravenously in Patients with Melanoma and Breast Carcinoma

Purpose

Treatments are limited for metastatic melanoma and metastatic triple-negative breast cancer (mTNBC). This pilot phase I trial (NCT03060356) examined the safety and feasibility of intravenous RNA-electroporated chimeric antigen receptor (CAR) T cells targeting the cell-surface antigen cMET.

Experimental Design

Metastatic melanoma or mTNBC subjects had at least 30% tumor expression of cMET, measurable disease and progression on prior therapy. Patients received up to six infusions (1 × 10e8 T cells/dose) of CAR T cells without lymphodepleting chemotherapy. Forty-eight percent of prescreened subjects met the cMET expression threshold. Seven (3 metastatic melanoma, 4 mTNBC) were treated.

Results

Mean age was 50 years (35-64); median Eastern Cooperative Oncology Group 0 (0-1); median prior lines of chemotherapy/immunotherapy were 4/0 for TNBC and 1/3 for melanoma subjects. Six patients experienced grade 1 or 2 toxicity. Toxicities in at least 1 patient included anemia, fatigue, and malaise. One subject had grade 1 cytokine release syndrome. No grade 3 or higher toxicity, neurotoxicity, or treatment discontinuation occurred. Best response was stable disease in 4 and disease progression in 3 subjects. mRNA signals corresponding to CAR T cells were detected by RT-PCR in all patients' blood including in 3 subjects on day +1 (no infusion administered on this day). Five subjects underwent postinfusion biopsy with no CAR T-cell signals seen in tumor. Three subjects had paired tumor tissue; IHC showed increases in CD8 and CD3 and decreases in pS6 and Ki67.

Conclusions

Intravenous administration of RNA-electroporated cMET-directed CAR T cells is safe and feasible.

Significance

Data evaluating CAR T therapy in patients with solid tumors are limited. This pilot clinical trial demonstrates that intravenous cMET-directed CAR T-cell therapy is safe and feasible in patients with metastatic melanoma and metastatic breast cancer, supporting the continued evaluation of cellular therapy for patients with these malignancies.

Chemoresistance in pancreatic ductal adenocarcinoma: Overcoming resistance to therapy

Pancreatic ductal adenocarcinoma (PDAC), a prominent cause of cancer deaths worldwide, is a highly aggressive cancer most frequently detected at an advanced stage that limits treatment options to systemic chemotherapy, which has provided only marginal positive clinical outcomes. More than 90% of patients with PDAC die within a year of being diagnosed. PDAC is increasing at a rate of 0.5-1.0% per year, and it is expected to be the second leading cause of cancer-related mortality by 2030. The resistance of tumor cells to chemotherapeutic drugs, which can be innate or acquired, is the primary factor contributing to the ineffectiveness of cancer treatments. Although many PDAC patients initially responds to standard of care (SOC) drugs they soon develop resistance caused partly by the substantial cellular heterogeneity seen in PDAC tissue and the tumor microenvironment (TME), which are considered key factors contributing to resistance to therapy. A deeper understanding of molecular mechanisms involved in PDAC progression and metastasis development, and the interplay of the TME in all these processes is essential to better comprehend the etiology and pathobiology of chemoresistance observed in PDAC. Recent research has recognized new therapeutic targets ushering in the development of innovative combinatorial therapies as well as enhancing our comprehension of several different cell death pathways. These approaches facilitate the lowering of the therapeutic threshold; however, the possibility of subsequent resistance development still remains a key issue and concern. Discoveries, that can target PDAC resistance, either alone or in combination, have the potential to serve as the foundation for future treatments that are effective without posing undue health risks. In this chapter, we discuss potential causes of PDAC chemoresistance and approaches for combating chemoresistance by targeting different pathways and different cellular functions associated with and mediating resistance.

Recent advances in targeted therapy for pancreatic adenocarcinoma

Pancreatic adenocarcinoma (PDAC) is a fatal disease with a 5-year survival rate of 8% and a median survival of 6 mo. In PDAC, several mutations in the genes are involved, with Kirsten rat sarcoma oncogene (90%), cyclin-dependent kinase inhibitor 2A (90%), and tumor suppressor 53 (75%–90%) being the most common. Mothers against decapentaplegic homolog 4 represents 50%. In addition, the self-preserving cancer stem cells, dense tumor microenvironment (fibrous accounting for 90% of the tumor volume), and suppressive and relatively depleted immune niche of PDAC are also constitutive and relevant elements of PDAC. Molecular targeted therapy is widely utilized and effective in several solid tumors. In PDAC, targeted therapy has been extensively evaluated; however, survival improvement of this aggressive disease using a targeted strategy has been minimal. There is currently only one United States Food and Drug Administration-approved targeted therapy for PDAC – erlotinib, but the absolute benefit of erlotinib in combination with gemcitabine is also minimal (2 wk). In this review, we summarize current targeted therapies and clinical trials targeting dysregulated signaling pathways and components of the PDAC oncogenic process, analyze possible reasons for the lack of positive results in clinical trials, and suggest ways to improve them. We also discuss emerging trends in targeted therapies for PDAC: combining targeted inhibitors of multiple pathways. The PubMed database and National Center for Biotechnology Information clinical trial website (www.clinicaltrials.gov) were queried to identify completed and published (PubMed) and ongoing (clinicaltrials.gov) clinical trials (from 2003-2022) using the keywords pancreatic cancer and targeted therapy. The PubMed database was also queried to search for information about the pathogenesis and molecular pathways of pancreatic cancer using the keywords pancreatic cancer and molecular pathways.

Development of a MET-targeted single-chain antibody fragment as an anti-oncogene targeted therapy for breast cancer

The usage of monoclonal antibodies (mAbs) and antibody fragments, as a matter associated with the biopharmaceutical industry, is increasingly growing. Harmonious with this concept, we designed an exclusive modeled single-chain variable fragment (scFv) against mesenchymal-epithelial transition (MET) oncoprotein. This scFv was newly developed from Onartuzumab sequence by gene cloning, and expression using bacterial host. Herein, we examined its preclinical efficacy for the reduction of tumor growth, invasiveness and angiogenesis in vitro and in vivo. Expressed anti-MET scFv demonstrated high binding capacity (48.8%) toward MET-overexpressing cancer cells. The IC₅₀ value of anti-MET scFv against MET-positive human breast cancer cell line (MDA-MB-435) was 8.4 µg/ml whereas this value was measured as 47.8 µg/ml in MET-negative cell line BT-483. Similar concentrations could also effectively induce apoptosis in MDA-MB-435 cancer cells. Moreover, this antibody fragment could reduce migration and invasion in MDA-MB-435 cells. Grafted breast tumors in Balb/c mice showed significant tumor growth suppression as well as reduction of blood-supply in response to recombinant anti-MET treatment. Histopathology and immunohistochemical assessments revealed higher rate of response to therapy. In our study, we designed and synthetized a novel anti-MET scFv which could effectively suppress MET-overexpressing breast cancer tumors.

The New Frontier of Immunotherapy: Chimeric Antigen Receptor T (CAR-T) Cell and Macrophage (CAR-M) Therapy against Breast Cancer

Breast cancer represents one of the most common tumor histologies. To date, based on the specific histotype, different therapeutic strategies, including immunotherapies, capable of prolonging survival are used. More recently, the astonishing results that were obtained from CAR-T cell therapy in haematological neoplasms led to the application of this new therapeutic strategy in solid tumors as well. Our article will deal with chimeric antigen receptor-based immunotherapy (CAR-T cell and CAR-M therapy) in breast cancer.

Correlation between hypoxia and HGF/c-MET expression in the management of pancreatic cancer

Pancreatic cancer (PC) is very deadly and difficult to treat. The presence of hypoxia has been shown to increase the probability of cancer developing and spreading. Pancreatic ductal adenocarcinoma (PDAC/PC) has traditionally viewed a highly lethal form of cancer due to its high occurrence of early metastases. Desmoplasia/stroma is often thick and collagenous, with pancreatic stellate cells as the primary source (PSCs). Cancer cells and other stromal cells interact with PSCs, promoting disease development. The hepatocyte growth factor (HGF)/c-MET pathway have been proposed as a growth factor mechanism mediating this interaction. Human growth factor (HGF) is secreted by pancreatic stellate cells (PSCs), and its receptor, c-MET, is generated by pancreatic cancer cells and endothelial cells. Hypoxia is frequent in malignant tumors, particularly pancreatic (PC). Hypoxia results from limitless tumor development and promotes survival, progression, and invasion. Hypoxic is becoming a critical driver and therapeutic target of pancreatic cancer as its hypoxia microenvironment is defined. Recent breakthroughs in cancer biology show that hypoxia promotes tumor proliferation, aggressiveness, and therapeutic resistance. Hypoxia-inducible factors (HIFs) stabilize hypoxia signaling. Hypoxia cMet is a key component of pancreatic tumor microenvironments, which also have a fibrotic response, that hypoxia, promotes and modulates. c-Met is a tyrosine-protein kinase. As describe it simply, the MET gene in humans' codes for a protein called hepatocyte growth factor receptor (HGFR). Most cancerous tumors and pancreatic cancer in particular, suffer from a lack of oxygen (PC). Due to unrestrained tumor development, hypoxia develops, actively contributing to tumor survival, progression, and invasion. As the processes by which hypoxia signaling promotes invasion and metastasis become clear, c-MET has emerged as an important determinant of pancreatic cancer malignancy and a potential pharmacological target. This manuscript provides the most current findings on the role of hypoxia and HGF/c-MET expression in the treatment of pancreatic cancer.

Anti-cancer drug molecules targeting cancer cell cycle and proliferation

Cancer, a vicious clinical burden that potentiates maximum fatality for humankind, arises due to unregulated excessive cell division and proliferation through an eccentric expression of cell cycle regulator proteins. A set of evolutionarily conserved machinery controls the cell cycle in an extremely precise manner so that a cell that went through the cycle can produce a genetically identical copy. To achieve perfection, several checkpoints were placed in the cycle for surveillance; so, errors during the division were rectified by the repair strategies. However, irreparable damage leads to exit from the cell cycle and induces programmed cell death. In comparison to a normal cell, cancer cells facilitate the constitutive activation of many dormant proteins and impede negative regulators of the checkpoint. Extensive studies in the last few decades on cell division and proliferation of cancer cells elucidate the molecular mechanism of the cell-cycle regulators that are often targeted for the development of anti-cancer therapy. Each phase of the cell cycle has been regulated by a unique set of proteins including master regulators Cyclins, and CDKs, along with the accessory proteins such as CKI, Cdc25, error-responsive proteins, and various kinase proteins mainly WEE1 kinases, Polo-like kinases, and Aurora kinases that control cell division. Here in this chapter, we have analytically discussed the role of cell cycle regulators and proliferation factors in cancer progression and the rationale of using various cell cycle-targeting drug molecules as anti-cancer therapy.

c-Met-targeted chimeric antigen receptor T cells inhibit hepatocellular carcinoma cells in vitro and in vivo

c-Met is a hepatocyte growth factor receptor overexpressed in many tumors such as hepatocellular carcinoma (HCC). Therefore, c-Met may serve as a promising target for HCC immunotherapy. Modifying T cells to express c-Met-specific chimeric antigen receptor (CAR) is an attractive strategy in treating c-Met-positive HCC. This study aimed to systematically evaluate the inhibitory effects of 2^nd- and 3^rd-generation c-Met CAR-T cells on hepatocellular carcinoma (HCC) cells. Here, 2^nd- and 3^rd-generation c-Met CARs containing an anti-c-Met single-chain variable fragment (scFv) as well as the CD28 signaling domain and CD3ζ (c-Met-28-3ζ), the CD137 signaling domain and CD3ζ (c-Met-137-3ζ), or the CD28 and CD137 signaling domains and CD3ζ (c-Met-28-137-3ζ) were constructed, and their abilities to target c-Met-positive HCC cells were evaluated in vitro and in vivo. All c-Met CARs were stably expressed on T cell membrane, and c-Met CAR-T cells aggregated around c-Met-positive HCC cells and specifically killed them in vitro. c-Met-28-137-3ζ CAR-T cells secreted more interferon-gamma (IFN-γ) and interleukin 2 (IL-2) than c-Met-28-3ζ CAR-T cells and c-Met-137-3ζ CAR-T cells. Compared with c-Met low-expressed cells, c-Met CAR-T cells secreted more cytokines when co-cultured with c-Met high-expressed cells. Moreover, c-Met-28-137-3ζ CAR-T cells eradicated HCC more effectively in xenograft tumor models compared with the control groups. This study suggests that 3^rd-generation c-Met CAR-T cells are more effective in inhibiting c-Met-positive HCC cells than 2^nd-generation c-Met CAR-T cells, thereby providing a promising therapeutic intervention for c-Met-positive HCC.

The Role of HGF/MET Signaling in Metastatic Uveal Melanoma

Simple Summary

Hepatocyte growth factor (HGF)/mesenchymal-epithelial transition factor (MET) signaling plays an important role in the metastatic formation and therapeutic resistance to uveal melanoma. Here, we review the various functions of MET signaling contributing to metastatic formation, as well as review resistance to treatments in metastatic uveal melanoma.

Abstract

Hepatocyte growth factor (HGF)/mesenchymal-epithelial transition factor (MET) signaling promotes tumorigenesis and tumor progression in various types of cancer, including uveal melanoma (UM). The roles of HGF/MET signaling have been studied in cell survival, proliferation, cell motility, and migration. Furthermore, HGF/MET signaling has emerged as a critical player not only in the tumor itself but also in the tumor microenvironment. Expression of MET is frequently observed in metastatic uveal melanoma and is associated with poor prognosis. It has been reported that HGF/MET signaling pathway activation is the major mechanism of treatment resistance in metastatic UM (MUM). To achieve maximal therapeutic benefit in MUM patients, it is important to understand how MET signaling drives cellular functions in uveal melanoma cells. Here, we review the HGF/MET signaling biology and the role of HGF/MET blockades in uveal melanoma.

Targeting Growth Factor Signaling Pathways in Pancreatic Cancer: Towards Inhibiting Chemoresistance

Pancreatic cancer is one of the most deadly cancers, ranking amongst the top leading cause of cancer related deaths in developed countries. Features such as dense stroma microenvironment, abnormal signaling pathways, and genetic heterogeneity of the tumors contribute to its chemoresistant characteristics. Amongst these features, growth factors have been observed to play crucial roles in cancer cell survival, progression, and chemoresistance. Here we review the role of the individual growth factors in pancreatic cancer chemoresistance. Importantly, the interplay between the tumor microenvironment and chemoresistance is explored in the context of pivotal role played by growth factors. We further describe current and future potential therapeutic targeting of these factors.

Targeting HGF/c-MET Axis in Pancreatic Cancer

Pancreatic cancer (pancreatic ductal adenocarcinoma (PDAC/PC)) has been an aggressive disease that is associated with early metastases. It is characterized by dense and collagenous desmoplasia/stroma, predominantly produced by pancreatic stellate cells (PSCs). PSCs interact with cancer cells as well as other stromal cells, facilitating disease progression. A candidate growth factor pathway that may mediate this interaction is the hepatocyte growth factor (HGF)/c-MET pathway. HGF is produced by PSCs and its receptor c-MET is expressed on pancreatic cancer cells and endothelial cells. The current review discusses the role of the MET/HGF axis in tumour progression and dissemination of pancreatic cancer. Therapeutic approaches that were developed targeting either the ligand (HGF) or the receptor (c-MET) have not been shown to translate well into clinical settings. We discuss a two-pronged approach of targeting both the components of this pathway to interrupt the stromal-tumour interactions, which may represent a potential therapeutic strategy to improve outcomes in PC.

cIRCR201-dPBD, a Novel Pyrrolobenzodiazepine Dimer-Containing Site-Specific Antibody-Drug Conjugate Targeting c-Met Overexpression Tumors

c-Met, as a receptor expressed on the cell membrane, contributes to the growth and metastasis of tumors, as well as angiogenesis, mainly through the hepatocyte growth factor (HGF)/c-Met axis during tumor progression. Although several c-Met inhibitors, including small molecules and monoclonal antibody inhibitors, are currently being investigated, their clinical outcomes have not been promising. Development of an antibody-drug conjugate (ADC) against c-Met could be an attractive therapeutic strategy that would provide superior antitumor efficacy with broad-spectrum c-Met expression levels. In the present study, site-specific drug-conjugate technology was applied to develop an ADC using the human-mouse cross-reactive c-Met antibody and a prodrug pyrrolobenzodiazepine (PBD). The toxin payload was uniformly conjugated to the light-chain C-terminus of the native cIRCR201 antibody (drug-to-antibody ratio = 2), as confirmed using LC-MS. Using a high-throughput screening system, we found that cIRCR201-dPBD exhibited varying sensitivities depending on the expression levels of c-Met, and it induced receptor-mediated endocytosis and toxin-mediated apoptosis in 47 different cancer cell lines. cIRCR201-dPBD also showed significant antitumor activity on the MET-amplified cancer cells using in vivo xenograft models. Therefore, cIRCR201-dPBD could be a promising therapeutic strategy for tumors with c-Met expression.

Format chain exchange (FORCE) for high-throughput generation of bispecific antibodies in combinatorial binder-format matrices

Generation of bispecific antibodies (bsAbs) requires a combination of compatible binders in formats that support desired functionalities. Here, we report that bsAb-matrices can be generated by Format Chain Exchange (FORCE), enabling screening of combinatorial binder/format spaces. Input molecules for generation of bi/multi-valent bsAbs are monospecific entities similar to knob-into-hole half-antibodies, yet with complementary CH3-interface-modulated and affinity-tagged dummy-chains. These contain mutations that lead to limited interface repulsions without compromising expression or biophysical properties of educts. Mild reduction of combinations of educts triggers spontaneous chain-exchange reactions driven by partially flawed CH3-educt interfaces resolving to perfect complementarity. This generates large bsAb matrices harboring different binders in multiple formats. Benign biophysical properties and good expression yields of educts, combined with simplicity of purification enables process automation. Examples that demonstrate the relevance of screening binder/format combinations are provided as a matrix of bsAbs that simultaneously bind Her1/Her2 and DR5 without encountering binder or format-inflicted interferences.

Bispecific antibodies have been generated in many different formats and it is becoming clear that rational design alone cannot create optimal functionalities. Here the authors introduce the high throughput methodology, Format Chain Exchange (FORCE), to enable combinatorial generation of bispecific antibodies.

The Novel Anti-cMet Antibody seeMet 12 Potentiates Sorafenib Therapy and Radiotherapy in a Colorectal Cancer Model

Rational

cMet is abnormally regulated in gastrointestinal cancer, and is associated with increased invasiveness of the disease and poor overall survival. There are indications that targeted therapy against cMet, alone or in combination with additional cancer therapies, can help improve treatment outcome. Thus, in the present study we investigated the therapeutic efficacy of a novel cMet-targeting antibody therapy in gastrointestinal cancer models, and assessed potential augmenting effects in combination with tyrosine kinase inhibitor (TKI) targeted therapy or radiotherapy.

Methods

Three different cMet-targeting antibodies were first characterized with respect to antigen binding and effects on cell viability in vitro. The best performing candidate seeMet 12 was then further assessed for effects on colorectal cancer cell growth, proliferation and migration. Combinations with the TKI-inhibitor sorafenib or external beam radiotherapy were then evaluated for potential additive or synergistic effects in vitro using monolayer- and multicellular tumor spheroid assays. Finally, the combination of seeMet 12 and radiotherapy was evaluated in vivo in a proof-of-concept colorectal cancer xenograft study.

Results

Dose-dependent therapeutic effects were demonstrated for all three cMet-targeting antibodies. Monotherapy using seeMet 12 resulted in impaired cellular migration/proliferation and reduced tumor spheroid growth. Moreover, seeMet 12 was able to potentiate therapeutic effects in vitro for both sorafenib and radiotherapy treatments. Finally, the in vivo therapy study demonstrated promising results, where a combination of seeMet 12 and fractionated radiotherapy increased median survival by 79% compared to radiotherapy alone, and tripled maximum survival.

Conclusion

The novel anti-cMet antibody seeMet 12 demonstrated therapeutic effects in cMet positive gastrointestinal cancer cells in vitro. Moreover, the addition of seeMet 12 augmented the effects of sorafenib and radiotherapy. An in vivo proof-of-concept study of seeMet 12 and radiotherapy further validated the results. Thus, cMet-targeted therapy should be further explored as a promising approach to increase therapeutic effects, circumvent treatment resistance, and reduce side effects.

Design, synthesis and biological evaluation of novel N-sulfonylamidine-based derivatives as c-Met inhibitors via Cu-catalyzed three-component reaction

In our continuing efforts to develop novel c-Met inhibitors as potential anticancer candidates, a series of new N-sulfonylamidine derivatives were designed, synthesized via Cu-catalyzed multicomponent reaction (MCR) as the key step, and evaluated for their in vitro biological activities against c-Met kinase and four cancer cell lines (A549, HT-29, MKN-45 and MDA-MB-231). Most of the target compounds showed moderate to significant potency at both the enzyme-based and cell-based assay and possessed selectivity for A549 and HT-29 cancer cell lines. The preliminary SAR studies demonstrated that compound 26af (c-Met IC₅₀ = 2.89 nM) was the most promising compound compared with the positive foretinib, which exhibited the remarkable antiproliferative activities, with IC₅₀ values ranging from 0.28 to 0.72 μM. Mechanistic studies of 26af showed the anticancer activity was closely related to the blocking phosphorylation of c-Met, leading to cell cycle arresting at G2/M phase and apoptosis of A549 cells by a concentration-dependent manner. The promising compound 26af was further identified as a relatively selective inhibitor of c-Met kinase, which also possessed an acceptable safety profile and favorable pharmacokinetic properties in BALB/c mouse. The favorable drug-likeness of 26af suggested that N-sulfonylamidines may be used as a promising scaffold for antitumor drug development. Additionally, the docking study and molecular dynamics simulations of 26af revealed a common mode of interaction with the binding site of c-Met. These positive results indicated that compound 26af is a potential anti-cancer candidate for clinical trials, and deserves further development as a selective c-Met inhibitor.

A novel non-agonist c-Met antibody drug conjugate with superior potency over a c-Met tyrosine kinase inhibitor in c-Met amplified and non-amplified cancers

c-Met is a well-characterized oncogene that is associated with poor prognosis in many solid tumor types. While responses to c-Met inhibitors have been observed in clinical trials, activity appears to be limited to those with MET gene amplifications or mutations. We developed a c-Met targeted antibody-drug conjugate (ADC) with preclinical activity in the absence of MET gene amplification or mutation, and activity even in the context of moderate protein expression. The ADC utilized a high-affinity c-Met antibody (P3D12), that induced c-Met degradation with minimal activation of c-Met signaling, or mitogenic effect. P3D12 was conjugated to the tubulin inhibitor toxin MMAF via a cleavable linker (vc-MMAF). P3D12-vc-MMAF demonstrated potent in vitro activity in c-Met protein-expressing cell lines regardless of MET gene amplification or mutation status, and retained activity in cell lines with medium-low c-Met protein expression. In contrast, the c-Met tyrosine kinase inhibitor (TKI) PHA-665752 slowed tumor cell growth in vitro only in the context of MET gene amplification or very high protein expression. This differential activity was even more marked in vivo. P3D12-vc-MMAF demonstrated robust inhibition of tumor growth in the MET gene amplified MKN-45 xenograft model, and similar results in H1975, which expresses moderate levels of wild type c-Met without genomic amplification. By comparison, the c-Met TKI, PHA-665752, demonstrated modest tumor growth inhibition in MKN-45, and no inhibition at all in H1975. Taken together, these data suggest that P3D12-vc-MMAF may have a superior clinical profile in treating c-Met positive malignancies in contrast to c-Met pathway inhibitors.

ImmunoPET Predicts Response to Met-targeted Radioligand Therapy in Models of Pancreatic Cancer Resistant to Met Kinase Inhibitors

Background: Pancreatic ductal adenocarcinoma (PDAC) has limited standard of care therapeutic options. While initially received with enthusiasm, results from targeted therapy with small molecule tyrosine kinases inhibitors (TKIs) have been mixed, in part due to poor patient selection and compensatory changes in signaling networks upon blockade of one or more kinase of tumors. Here, we demonstrate that in PDACs otherwise resistant to rational kinase inhibition, Met-directed immuno-positron emission tomography (immunoPET) can identify targets for cell-signaling independent targeted radioligand therapy (RLT). In this study, we use Met-directed immunoPET and RLT in models of human pancreatic cancer that are resistant to Met- and MEK-selective TKIs, despite over-expression of Met and KRAS-pathway activation. Methods: We assessed cell membrane Met levels in human patient samples and pancreatic ductal adenocarcinoma (PDAC) cell lines (BxPC3, Capan2, Suit2, and MIA PaCa-2) using immunofluorescence, flow cytometry and cell-surface biotinylation assays. To determine whether Met expression levels correlate with sensitivity to Met inhibition by tyrosine kinase inhibitors (TKIs), we performed cell viability studies. A Met-directed imaging agent was engineered by labeling Met-specific onartuzumab with zirconium-89 (Zr-89) and its in vivo performance was evaluated in subcutaneous and orthotopic PDAC xenograft models. To assess whether the immunoPET agent would predict for targeted RLT response, onartuzumab was then labeled with lutetium (Lu-177) as the therapeutic radionuclide to generate our [¹⁷⁷Lu]Lu-DTPA-onartuzumab RLT agent. [¹⁷⁷Lu]Lu-DTPA-onartuzumab was administered at 9.25MBq (250μCi)/20μg in three fractions separated by three days in mice subcutaneously engrafted with BxPC3 (high cell-membrane Met) or MIA PaCa-2 (low cell-membrane Met). Primary endpoints were tumor response and overall survival. Results: Flow cytometry and cell-surface biotinylation studies showed that cell-membrane Met was significantly more abundant in BxPC3, Capan2, and Suit2 when compared with MIA PaCa-2 pancreatic tumor cells. Crizotinib and cabozantinib, TKIs with known activity against Met and other kinases, decreased PDAC cell line viability in vitro. The TKI with the lowest IC₅₀ for Met, capmatinib, had no activity in PDAC lines. No additive effect was detected on cell viability when Met-inhibition was combined with MEK1/2 inhibition. We observed selective tumor uptake of [⁸⁹Zr]Zr-DFO-onartuzumab in mice subcutaneously and orthotopically engrafted with PDAC lines containing high cell-surface levels of Met (BxPC3, Capan2, Suit2), but not in mice engrafted with low cell-surface levels of Met (MIA PaCa-2). Significant tumor growth delay and overall survival benefit were observed in both BxPC3 and MIA PaCa-2 engrafted animals treated with RLT when compared to controls, however, the benefit was more pronounced and more durable in the BxPC3 engrafted animals treated with [¹⁷⁷Lu]Lu-DTPA-onartuzumab RLT. Conclusions: Our findings demonstrate that while over-expression of Met is not predictive of Met-directed TKI response, immunoPET can detect Met over-expression in vivo and predicts for therapeutic response to Met-selective RLT. This phenomenon can be exploited for other Met-overexpressing tumor types specifically, and to any differentially overexpressed surface molecule more broadly.

Preparation of a Novel One-Armed Anti-c-Met Antibody with Antitumor Activity Against Hepatocellular Carcinoma

Introduction

Antibody-based c-mesenchymal–epithelial transition factor (c-Met) inhibition is a promising strategy for hepatocellular carcinoma (HCC) treatment, but the intrinsic agonistic activity of the anti-c-Met antibody limits its application in drug development. Constructing a monovalent one-armed antibody has been reported to be an effective way to create an inhibitory anti-c-Met antibody.

Materials and methods

In the present study, a novel monovalent one-armed anti-c-Met antibody was constructed using the knobs-into-holes technology, and its inhibitory effects against HCC and the underlying mechanisms were explored.

Results

The one-armed anti-c-Met antibody blocked the hepatocyte growth factor (HGF)/c-Met interaction and the subsequent signal transduction, including phosphorylation of c-Met, Grb2-associated binding protein 1(Gab-1), extracellular regulated protein kinases 1/2(Erk1/2), and Akt, also referred to as protein kinase B (PKB) in HCC cell line HepG2. Furthermore, the autocrine stimulation of HepG2 cell proliferation and HGF-induced HCC cell migration were strongly inhibited by the one-armed anti-c-Met antibody. In addition, the antibody also reduced the HGF-induced proliferation and tube formation of human umbilical vein endothelial cells (HUVECs). Treating HepG2-bearing mice with the one-armed anti-c-Met antibody significantly inhibited the tumor growth in the xenograft nude mouse model.

Conclusion

The one-armed anti-c-Met antibody derived from the full-length bivalent anti-c-Met antibody might serve as a potential antitumor agent against HCC.

SHR-A1403, a novel c-mesenchymal-epithelial transition factor (c-Met) antibody-drug conjugate, overcomes AZD9291 resistance in non-small cell lung cancer cells overexpressing c-Met

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) have been used as the first-line treatment of non-small cell lung cancers (NSCLC) harboring EGFR-activating mutations, but acquired resistance is ubiquitous and needs to be solved urgently. Here, we introduce an effective approach for overcoming resistance to the EGFR-TKI, AZD9291, in NSCLC cells using SHR-A1403, a novel c-mesenchymal-epithelial transition factor (c-Met)-targeting antibody-drug conjugate (ADC) consisting of an anti-c-Met monoclonal antibody (c-Met mAb) conjugated to a microtubule inhibitor. Resistant cells were established by exposing HCC827 to increasing concentrations of EGFR-TKI. c-Met was found to be overexpressed in most resistant cells. AZD9291 resistance was partially restored by combination of AZD9291 and crizotinib only in resistant cells overexpressing phospho-c-Met, which synergistically inhibited c-Met-mediated phosphorylation of the downstream targets ERK1/2 and AKT. In resistant cells overexpressing c-Met, neither crizotinib nor c-Met mAb was able to overcome AZD9291 resistance. In contrast, SHR-A1403 strongly inhibited proliferation of AZD9291-resistant HCC827 overexpressing c-Met, regardless of the levels of c-Met phosphorylation. SHR-A1403 bound to resistant cells overexpressing c-Met was internalized into cells and released associated microtubule inhibitor, resulting in cell-killing activity that was dependent on c-Met expression levels only, irrespective of the involvement of c-Met or EGFR signaling in AZD9291 resistance. Consistent with its activity in vitro, SHR-A1403 significantly inhibited the growth of AZD9291-resistant HCC827 tumors and caused tumor regression in vivo. Thus, our findings show that SHR-A1403 efficiently overcomes AZD9291 resistance in cells overexpressing c-Met, and further indicate that c-Met expression level is a biomarker predictive of SHR-A1403 efficacy.

High-Affinity Human Anti-c-Met IgG Conjugated to Oxaliplatin as Targeted Chemotherapy for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most mortality-causing solid cancers globally and the second largest cause of death among malignancies. Oxaliplatin, a platinum-based drug, has been widely utilized in the treatment of malignancies such as colorectal cancer and hepatocellular carcinoma, yet its usage is limited because of severe side effects of cytotoxicity to normal tissues. c-Met, a receptor tyrosine kinase, is expressed aberrantly on the surface of HCC. The purpose of this study was to synthesise a humanized antibody against c-Met (anti-c-Met IgG) and conjugate it to oxaliplatin to develop a novel antibody-drug conjugate (ADC). Anti-c-Met IgG was detected to be loaded with ~4.35 moles oxaliplatin per mole of antibody. ELISA and FCM confirmed that ADC retained a high and selective binding affinity for c-Met protein and c-Met-positive HepG2 cells. In vitro, the cytotoxicity tests and biological function assay indicated that ADC showed much higher cytotoxicity and functioning in c-Met-positive HepG2 cells, compared with shMet-HepG2 cells expressing lower levels of c-Met. Furthermore, compared with free oxaliplatin, ADC significantly improved cytotoxicity to c-Met-positive tumours and avoided off-target cell toxicity in vivo. In conclusion, by targeting c-Met-expressing hepatoma cells, ADC can provide a platform to reduce drug toxicity and improve drug efficacy in vitro and in vivo.

SHR-A1403, a novel c-Met antibody-drug conjugate, exerts encouraging anti-tumor activity in c-Met-overexpressing models

Emerging evidence demonstrates that a c-Met antibody-drug conjugate (ADC) has superior efficacy and safety profiles compared with those of currently available small molecules or antibody inhibitors for the treatment of c-Met-overexpressing cancers. Here we described both the in vitro and in vivo efficacies of SHR-A1403, a novel c-Met ADC composed of a humanized IgG2 monoclonal antibody against c-Met conjugated to a novel cytotoxic microtubule inhibitor. SHR-A1403 showed high affinity to c-Met proteins derived from human or monkey and potent inhibitory effects in cancer cell lines with high c-Met protein expression. In mice bearing tumors derived from cancer cell lines or patient HCC tissues with confirmed c-Met overexpression, SHR-A1403 showed excellent anti-tumor efficacy. Antibody binding with c-Met contributed to SHR-A1403 endocytosis; the subsequent translocation to lysosomes and cytotoxicity of the released toxin are speculated to be predominant mechanisms underlying the anti-tumor activity of SHR-A1403. In conclusion, SHR-A1403 showed significant anti-tumor activity in cancer cell lines, xenograft mouse models and an HCC PDX model, which all have high c-Met levels. These data provide references for SHR-A1403 as a potential therapy for the treatment of cancers with c-Met overexpression.

Inhibition of the MET Kinase Activity and Cell Growth in MET-Addicted Cancer Cells by Bi-Paratopic Linking

MET, the product of the c-MET proto-oncogene, and its ligand hepatocyte growth factor/scatter factor (HGF/SF) control survival, proliferation and migration during development and tissue regeneration. HGF/SF-MET signaling is equally crucial for growth and metastasis of a variety of human tumors, but resistance to small-molecule inhibitors of MET kinase develops rapidly and therapeutic antibody targeting remains challenging. We made use of the designed ankyrin repeat protein (DARPin) technology to develop an alternative approach for inhibiting MET. We generated a collection of MET-binding DARPins covering epitopes in the extracellular MET domains and created comprehensive sets of bi-paratopic fusion proteins. This new class of molecules efficiently inhibited MET kinase activity and downstream signaling, caused receptor downregulation and strongly inhibited the proliferation of MET-dependent gastric carcinoma cells carrying MET locus amplifications. MET-specific bi-paratopic DARPins may represent a novel and potent strategy for therapeutic targeting of MET and other receptors, and this study has elucidated their mode of action.

Induction of MET Receptor Tyrosine Kinase Down-regulation through Antibody-mediated Receptor Clustering

The proto-oncoprotein MET is a receptor tyrosine kinase that plays a key role in cancer cell growth and invasion. We have used fluorescence-tagged antibodies to activate MET in live serum-starved glioblastoma cells and monitor the fate of antibody-bound MET receptor in single cell-based assays. We found that the antibodies induced rapid and transient formation of highly polarized MET clusters on the plasma membrane and promoted the activation of MET, resembling the initial effects of binding to its ligand, HGF. However, the antibody-induced clustering and activation of MET led to the rapid removal of the receptor from cell surface and altered its intracellular processing, resulted in rapid degradation of the receptor. Consequently, while cells pre-treated with HGF remain competent to respond to further HGF stimulation, cells pre-treated with antibodies are refractory to further HGF stimulation due to antibody-mediated MET depletion. Removal of MET by sustained treatment of antibodies blocked cancer cell migration and invasion. Our studies reveal a novel mechanism to alter the recycling process of MET in glioblastoma cancer cells by promoting the receptor degradation through a proteasome-sensitive and lysosome-dependent pathway through the ligand-independent activation of MET using anti-MET antibodies.

Anti-MET VHH Pool Overcomes MET-Targeted Cancer Therapeutic Resistance

Receptor tyrosine kinase MET and its ligand hepatocyte growth factor (HGF) play crucial roles in many human malignancies. Numerous drugs have been developed against kinase center of MET or HGF-mediated activation; however, the outcomes in patients are not so promising. Increasing evidence show that MET has kinase-independent effects on tumorigenesis and dissemination, which explains the low efficacy in kinase inhibition-based strategy. VHH is the recombinant variable region of Camelid heavy-chain antibody. As a nanoscale antigen-binding unit, VHH has become an appealing drug candidate in cancer therapy. In our study, we choose a novel strategy to construct an anti-MET VHH pool against the whole ecto-domain of MET. Comparing to monoclonal antibody or single VHH, the anti-MET VHH pool strongly promotes MET degradation through Clathrin-dependent endo-lysosomal pathway. Thus, the anti-MET VHH pool not only blocks kinase activity of MET, but also reduces protein level of MET. As a consequence, anti-MET VHH pool dramatically suppresses cancer cell proliferation, viability, and colony formation in vitro, and inhibits tumorigenesis and growth in mice. Taken together, VHH pool-based strategy greatly improves MET-targeted therapeutic effects on cancer.

Safety and Efficacy of Intratumoral Injections of Chimeric Antigen Receptor (CAR) T Cells in Metastatic Breast Cancer

Chimeric antigen receptors (CAR) are synthetic molecules that provide new specificities to T cells. Although successful in treatment of hematologic malignancies, CAR T cells are ineffective for solid tumors to date. We found that the cell-surface molecule c-Met was expressed in ∼50% of breast tumors, prompting the construction of a CAR T cell specific for c-Met, which halted tumor growth in immune-incompetent mice with tumor xenografts. We then evaluated the safety and feasibility of treating metastatic breast cancer with intratumoral administration of mRNA-transfected c-Met-CAR T cells in a phase 0 clinical trial (NCT01837602). Introducing the CAR construct via mRNA ensured safety by limiting the nontumor cell effects (on-target/off-tumor) of targeting c-Met. Patients with metastatic breast cancer with accessible cutaneous or lymph node metastases received a single intratumoral injection of 3 × 107 or 3 × 108 cells. CAR T mRNA was detectable in peripheral blood and in the injected tumor tissues after intratumoral injection in 2 and 4 patients, respectively. mRNA c-Met-CAR T cell injections were well tolerated, as none of the patients had study drug-related adverse effects greater than grade 1. Tumors treated with intratumoral injected mRNA c-Met-CAR T cells were excised and analyzed by immunohistochemistry, revealing extensive tumor necrosis at the injection site, cellular debris, loss of c-Met immunoreactivity, all surrounded by macrophages at the leading edges and within necrotic zones. We conclude that intratumoral injections of mRNA c-Met-CAR T cells are well tolerated and evoke an inflammatory response within tumors. Cancer Immunol Res; 5(12); 1152-61. ©2017 AACR.

C-Met as a potential target for the treatment of gastrointestinal cancer: Current status and future perspectives

Aberrant activation of the HGF/c-Met signalling pathways is shown to be related with cell proliferation, progression, metastasis, and worse prognosis in several tumor types, including gastrointestinal cancers, suggesting its value as a stimulating-target for cancer-therapy. Several approaches have been developed for targeting HGF and/or c-Met, and one of them, crizotinib (dual c-Met/ALK inhibitor), is recently been approved by FDA for lung-cancers with ALK-rearrangement. The main aim of current review is to give an overview on the role of c-Met/HGF pathway in gastrointestinal cancer, in preclinical and clinical trials. Although several important matters is still remained to be elucidated on the molecular pathways underlying the antitumor effects of this therapy in gastrointestinal-cancers. Further investigations are warranted to recognize the main determinants of the activity of c-Met inhibitors, for parallel targeting signalling pathway associated/activated via MET/HGF pathway or in response to the cell resistance to anti-c-Met agents. Additionally, identification of patients that might benefit from therapy could help to increase the selectivity and efficacy of the therapy.

Dual Inhibition of Hedgehog and c-Met Pathways for Pancreatic Cancer Treatment

Pancreatic ductal adenocarcinoma (PDAC) is one of the most chemotherapy- and radiotherapy-resistant tumors. The c-Met and Hedgehog (Hh) pathways have been shown previously by our group to be key regulatory pathways in the primary tumor growth and metastases formation. Targeting both the HGF/c-Met and Hh pathways has shown promising results in preclinical studies; however, the benefits were not readily translated into clinical trials with PDAC patients. In this study, utilizing mouse models of PDAC, we showed that inhibition of either HGF/c-Met or Hh pathways sensitize the PDAC tumors to gemcitabine, resulting in decreased primary tumor volume as well as significant reduction of metastatic tumor burden. However, prolonged treatment of single HGF/c-Met or Hh inhibitor leads to resistance to these single inhibitors, likely because the single c-Met treatment leads to enhanced expression of Shh, and vice versa. Targeting both the HGF/c-Met and Hh pathways simultaneously overcame the resistance to the single-inhibitor treatment and led to a more potent antitumor effect in combination with the chemotherapy treatment. Mol Cancer Ther; 16(11); 2399-409. ©2017 AACR.

Comparison of the c-MET gene amplification between primary tumor and metastatic lymph nodes in non-small cell lung cancer

BACKGROUND

c-MET has recently been identified as a promising novel target in non-small cell lung cancer (NSCLC). We detected the consistency of c-MET gene amplification in metastatic lymph nodes and tumor tissues of NSCLC patients and discuss the clinical application value of c-MET gene amplification in metastatic lymph nodes.

METHODS

Real-time fluorescent quantitative PCR was used to test tumor tissues in 368 NSCLC patients and 178 paired metastatic lymph node samples. The amplification consistency in metastatic lymph nodes and tissue samples were compared and the correlation between c-MET gene amplification and the clinical characteristics of patients was analyzed.

RESULTS

The c-MET gene amplification rate was 8.97% (33/368) in tumor tissues. Of the 178 paired cases, c-MET gene amplification was positive in 7.95% (15/178) of cancerous tissues and 18.54% (33/178) of metastatic lymph nodes. c-MET gene amplification was detected more frequently in metastatic lymph nodes than in primary cancerous tissue. When metastatic lymph nodes were used as surrogate samples of primary cancerous tissues, the sensitivity was 86.67% (13/15) and the specificity was 87.69% (143/163).

CONCLUSIONS

Screening for c-MET gene amplification in lymph node metastases could determine which patients are eligible for tyrosine kinase inhibitor therapy. Lymph node metastasis can predict c-MET gene amplification in a primary tumor and guide the clinical use of c-MET gene targeted drugs.

Efficient generation of bispecific IgG antibodies by split intein mediated protein trans-splicing system

Many methods have been developed to produce bispecific antibodies (BsAbs) for industrial application. However, huge challenges still remain in synthesizing whole length BsAbs, including their assembly, stability, immunogenicity, and pharmacodynamics. Here we present for first time a generic technology platform of generating bispecific IgG antibodies, “Bispecific Antibody by Protein Trans-splicing (BAPTS)”. Different from published methods, we assembled two parental antibody fragments in the hinge region by the protein trans-splicing reaction of a split intein to generate BsAbs without heavy/heavy and light/heavy chain mispairing. Utilizing this simple and efficient approach, there have been several BsAbs (CD3×HER2, CD3×EGFR, EGFR×HER2) synthesized to demonstrate its broad applicability. Correctly paired mAb arms were assembled to form BsAbs that were purified through protein A affinity chromatography to demonstrate industrial applicability at large scale. Further, the products were characterized through physical-biochemistry properties and biological activities to confirm expected quality of the products from “BAPTS”. More importantly, correct pairing was confirmed by mass spectrum. Proof-of-concept studies with CD3×HER2 BsAb (T-cell recruitment) demonstrated superior bioactivity compared with trastuzumab. The results of undetectable mispairing and high biological activity have indicated that this method has the potential to be utilized to manufacture BsAbs with high efficiency at industrial scale.

Computational design of a specific heavy chain/κ light chain interface for expressing fully IgG bispecific antibodies

The use of bispecific antibodies (BsAbs) to treat human diseases is on the rise. Increasingly complex and powerful therapeutic mechanisms made possible by BsAbs are spurring innovation of novel BsAb formats and methods for their production. The long-lived in vivo pharmacokinetics, optimal biophysical properties and potential effector functions of natural IgG monoclonal (and monospecific) antibodies has resulted in a push to generate fully IgG BsAb formats with the same quaternary structure as monoclonal IgGs. The production of fully IgG BsAbs is challenging because of the highly heterogeneous pairing of heavy chains (HCs) and light chains (LCs) when produced in mammalian cells with two IgG HCs and two LCs. A solution to the HC heterodimerization aspect of IgG BsAb production was first discovered two decades ago; however, addressing the LC mispairing issue has remained intractable until recently. Here, we use computational and rational engineering to develop novel designs to the HC/LC pairing issue, and particularly for κ LCs. Crystal structures of these designs highlight the interactions that provide HC/LC specificity. We produce and characterize multiple fully IgG BsAbs using these novel designs. We demonstrate the importance of specificity engineering in both the variable and constant domains to achieve robust HC/LC specificity within all the BsAbs. These solutions facilitate the production of fully IgG BsAbs for clinical use.

A "Prozone-Like" Effect Influences the Efficacy of the Monoclonal Antibody ABT-700 against the Hepatocyte Growth Factor Receptor

ABT-700 is a therapeutic antibody against the hepatocyte growth factor receptor (MET). At doses or regimens that lead to exposures exceeding optimum in vivo, the efficacy of ABT-700 is unexpectedly reduced. We hypothesized that this reduction in efficacy was due to a "prozone-like" effect in vivo. A prozone-like effect, which is a reduction in efficacy beyond optimum exposure, is caused due a mechanism similar to the generation of false negative flocculation tests by excessive antibody titres. In vitro, we demonstrate that at higher ABT-700 concentrations, this "prozone-like" effect is mediated by a progressive conversion from bivalent to ineffective monovalent binding of the antibody. In vivo, the efficacy of ABT-700 is dependent on an optimum range of exposure as well. Our data suggest that the "prozone-like" effect is operative and independent of target expression. ABT-700 dose, regimen, exposure, and tumor burden are interdependent variables influencing the "prozone-like" effect and mediating and in vivo efficacy. By optimization of dosage and regimen we demonstrate that the "prozone-like" effect can be alleviated and ABT-700 efficacy at varying tumor loads can be further extended in combination with cisplatin. Our results suggest that optimization of exposure taking tumor burden into account may alleviate "prozone-like" effects without compromising efficacy.

Sym015: A Highly Efficacious Antibody Mixture against MET-Amplified Tumors

Purpose: Activation of the receptor tyrosine kinase MET is associated with poor clinical outcome in certain cancers. To target MET more effectively, we developed an antagonistic antibody mixture, Sym015, consisting of two humanized mAbs directed against nonoverlapping epitopes of MET.Experimental Design/Results: We screened a large panel of well-annotated human cancer cell lines and identified a subset with highly elevated MET expression. In particular, cell lines of lung cancer and gastric cancer origin demonstrated high MET expression and activation, and Sym015 triggered degradation of MET and significantly inhibited growth of these cell lines. Next, we tested Sym015 in patient- and cell line-derived xenograft models with high MET expression and/or MET exon 14 skipping alterations, and in models harboring MET amplification as a mechanism of resistance to EGFR-targeting agents. Sym015 effectively inhibited tumor growth in all these models and was superior to an analogue of emibetuzumab, a monoclonal IgG4 antibody against MET currently in clinical development. Sym015 also induced antibody-dependent cellular cytotoxicity (ADCC) in vitro, suggesting that secondary effector functions contribute to the efficacy of Sym015.Retrospectively, all responsive, high MET-expressing models were scored as highly MET-amplified by in situ hybridization, pointing to MET amplification as a predictive biomarker for efficacy. Preclinical toxicology studies in monkeys showed that Sym015 was well tolerated, with a pharmacokinetic profile supporting administration of Sym015 every second or third week in humans.Conclusions: The preclinical efficacy and safety data provide a clear rationale for the ongoing clinical studies of Sym015 in patients with MET-amplified tumors. Clin Cancer Res; 23(19); 5923-35. ©2017 AACR.

The c-Met receptor: Implication for targeted therapies in colorectal cancer

c-Met (mesenchymal–epithelial transition factor) is a tyrosine kinase receptor activated by hepatocyte growth factor and regulates multiple biological processes, such as cell scattering, survival, and proliferation. Aberrant c-Met signaling has been implicated in a variety of cancer types, including colorectal cancer. c-Met is genetically altered through various mechanisms that is associated with colorectal cancer progression and metastasis. Especially, in colorectal cancer, preclinical evidence for the aberrant activation of the c-Met signaling exists. Accordingly, molecular targeting of c-Met receptor could be a promising strategy, in the treatment of colorectal cancer patients. Recently, it was also shown that crosstalk between c-Met and other cell surface receptors attributes to tumorigenesis and development of therapeutic resistance. Characterization of the molecular mechanisms through which c-Met crosstalks with other receptors in favor of tumor formation and progression remains to explore. This review will describe the mechanisms of aberrant c-Met signaling in colorectal cancer and discuss on additional roles for c-Met receptor through crosstalk with other tyrosine kinase receptors and cell surface proteins in colorectal cancer. Novel therapeutic approaches for c-Met pathway targeting will also be discussed.

Hinge-deleted IgG4 blocker therapy for acetylcholine receptor myasthenia gravis in rhesus monkeys

Autoantibodies against ion channels are the cause of numerous neurologic autoimmune disorders. Frequently, such pathogenic autoantibodies have a restricted epitope-specificity. In such cases, competing antibody formats devoid of pathogenic effector functions (blocker antibodies) have the potential to treat disease by displacing autoantibodies from their target. Here, we have used a model of the neuromuscular autoimmune disease myasthenia gravis in rhesus monkeys (Macaca mulatta) to test the therapeutic potential of a new blocker antibody: MG was induced by passive transfer of pathogenic acetylcholine receptor-specific monoclonal antibody IgG1-637. The effect of the blocker antibody (IgG4Δhinge-637, the hinge-deleted IgG4 version of IgG1-637) was assessed using decrement measurements and single-fiber electromyography. Three daily doses of 1.7 mg/kg IgG1-637 (cumulative dose 5 mg/kg) induced impairment of neuromuscular transmission, as demonstrated by significantly increased jitter, synaptic transmission failures (blockings) and a decrease in the amplitude of the compound muscle action potentials during repeated stimulations (decrement), without showing overt symptoms of muscle weakness. Treatment with three daily doses of 10 mg/kg IgG4Δhinge-637 significantly reduced the IgG1-637-induced increase in jitter, blockings and decrement. Together, these results represent proof-of principle data for therapy of acetylcholine receptor-myasthenia gravis with a monovalent antibody format that blocks binding of pathogenic autoantibodies.

MK2461, a Multitargeted Kinase Inhibitor, Suppresses the Progression of Pancreatic Cancer by Disrupting the Interaction Between Pancreatic Cancer Cells and Stellate Cells

OBJECTIVES

Platelet-derived growth factor receptor beta (PDGFRβ) and hepatocyte growth factor receptor (MET) expressed on pancreatic stellate cells (PSCs) are suggested as important components modulating the interactions between pancreatic cancer cells (PCCs) and PSCs. The objective of this study is to clarify the effect of MK2461, a multikinase inhibitor targeting MET and PDGFRβ, on the interaction between PCCs and PSCs.

METHODS

In this study, we profiled the expression of receptor tyrosine kinases (including PDGFRβ and MET) in pancreatic cancer with quantitative targeted absolute proteomics using liquid chromatography tandem mass spectrometry. In addition, the effect of MK2461 on PCC-PSC interaction was investigated using PSCs prepared from pancreatic cancer tissues.

RESULTS

In PSCs, PDGFRβ and MET were upregulated compared with other receptor tyrosine kinases. Conditioned medium from PSCs promoted the proliferation of PCCs, and vice versa. Moreover, MK2461 suppressed the effects of conditioned medium on PCCs and PSCs. Finally, MK2461 significantly inhibited tumor growth in mice coinjected with PCCs and PSCs.

CONCLUSIONS

The PDGFRβ and MET may play a critical role in the interaction between PCCs and PSCs, which was modulated by MK2461. Therefore, MK2461 may have therapeutic potential in the treatment of pancreatic cancer.

Progress of antibody-based inhibitors of the HGF-cMET axis in cancer therapy

Dysregulated receptor tyrosine kinase signaling in human cancer cells leads to tumor progression, invasion and metastasis. The receptor tyrosine kinase cMET is frequently overexpressed in cancer tissue, and activation of cMET signaling is related to drug resistance and the processes of carcinogenesis, invasion and metastasis. For that reason, cMET and its ligand, hepatocyte growth factor (HGF), are considered prime targets for the development of anticancer drugs. At least eight anti-cMET and four anti-HGF antibodies have been tested or are being tested in clinical trials. However, to date none of these HGF/cMET inhibitors have shown significant efficacy in clinical trials. Furthermore, no receptor tyrosine kinase inhibitors primarily targeting cMET have been approved. Given that neutralization of HGF or cMET does not cause significant adverse effects, inhibition of the HGF/cMET signaling pathway appears to be safe. In this review, we summarized the completed and ongoing clinical trials testing antibody- or protein-based anticancer drugs targeting cMET and HGF.

MET Tyrosine Kinase Inhibition Enhances the Antitumor Efficacy of an HGF Antibody

Receptor tyrosine kinase therapies have proven to be efficacious in specific cancer patient populations; however, a significant limitation of tyrosine kinase inhibitor (TKI) treatment is the emergence of resistance mechanisms leading to a transient, partial, or complete lack of response. Combination therapies using agents with synergistic activity have potential to improve response and reduce acquired resistance. Chemoreagent or TKI treatment can lead to increased expression of hepatocyte growth factor (HGF) and/or MET, and this effect correlates with increased metastasis and poor prognosis. Despite MET's role in resistance and cancer biology, MET TKI monotherapy has yielded disappointing clinical responses. In this study, we describe the biological activity of a selective, oral MET TKI with slow off-rate and its synergistic antitumor effects when combined with an anti-HGF antibody. We evaluated the combined action of simultaneously neutralizing HGF ligand and inhibiting MET kinase activity in two cancer xenograft models that exhibit autocrine HGF/MET activation. The combination therapy results in additive antitumor activity in KP4 pancreatic tumors and synergistic activity in U-87MG glioblastoma tumors. Pharmacodynamic characterization of biomarkers that correlate with combination synergy reveal that monotherapies induce an increase in the total MET protein, whereas combination therapy significantly reduces total MET protein levels and phosphorylation of 4E-BP1. These results hold promise that dual targeting of HGF and MET by combining extracellular ligand inhibitors with intracellular MET TKIs could be an effective intervention strategy for cancer patients who have acquired resistance that is dependent on total MET protein. Mol Cancer Ther; 16(7); 1269-78. ©2017 AACR.

Endoscopic ultrasound-guided fine-needle aspirate-derived preclinical pancreatic cancer models reveal panitumumab sensitivity in KRAS wild-type tumors

Pancreatic cancer (PC) is largely refractory to existing therapies used in unselected patient trials, thus emphasizing the pressing need for new approaches for patient selection in personalized medicine. KRAS mutations occur in 90% of PC patients and confer resistance to epidermal growth factor receptor (EGFR) inhibitors (e.g., panitumumab), suggesting that KRAS wild-type PC patients may benefit from targeted panitumumab therapy. Here, we use tumor tissue procured by endoscopic ultrasound-guided fine-needle aspirate (EUS-FNA) to compare the in vivo sensitivity in patient-derived xenografts (PDXs) of KRAS wild-type and mutant PC tumors to panitumumab, and to profile the molecular signature of these tumors in patients with metastatic or localized disease. Specifically, RNASeq of EUS-FNA-derived tumor RNA from localized (n = 20) and metastatic (n = 20) PC cases revealed a comparable transcriptome profile. Screening the KRAS mutation status of tumor genomic DNA obtained from EUS-FNAs stratified PC patients into either KRAS wild-type or mutant cohorts, and the engraftment of representative KRAS wild-type and mutant EUS-FNA tumor samples into NOD/SCID mice revealed that the growth of KRAS wild-type, but not mutant, PDXs was selectively suppressed with panitumumab. Furthermore, in silico transcriptome interrogation of The Cancer Genome Atlas (TCGA)-derived KRAS wild-type (n = 38) and mutant (n = 132) PC tumors revealed 391 differentially expressed genes. Taken together, our study validates EUS-FNA for the application of a novel translational pipeline comprising KRAS mutation screening and PDXs, applicable to all PC patients, to evaluate personalized anti-EGFR therapy in patients with KRAS wild-type tumors.