MET and RON receptor tyrosine kinases in colorectal adenocarcinoma: molecular features as drug targets and antibody-drug conjugates for therapy

Conformation specific antagonistic high affinity antibodies to the RON receptor kinase for imaging and therapy

The RON receptor tyrosine kinase is an exceptionally interesting target in oncology and immunology. It is not only overexpressed in a wide variety of tumors but also has been shown to be expressed on myeloid cells associated with tumor infiltration, where it serves to dampen tumour immune responses and reduce the efficacy of anti-CTLA4 therapy. Potent and selective inhibitory antibodies to RON might therefore both inhibit tumor cell growth and stimulate immune rejection of tumors. We derived cloned and sequenced a new panel of exceptionally avid anti-RON antibodies with picomolar binding affinities that inhibit MSP-induced RON signaling and show remarkable potency in antibody dependent cellular cytotoxicity. Antibody specificity was validated by cloning the antibody genes and creating recombinant antibodies and by the use of RON knock out cell lines. When radiolabeled with 89-Zirconium, the new antibodies 3F8 and 10G1 allow effective immuno-positron emission tomography (immunoPET) imaging of RON-expressing tumors and recognize universally exposed RON epitopes at the cell surface. The 10G1 was further developed into a novel bispecific T cell engager with a 15 pM EC50 in cytotoxic T cell killing assays.

Identification of (S)-1-(2-(2,4-difluorophenyl)-4-oxothiazolidin-3-yl)-3-(4-((7-(3-(4-ethylpiperazin-1-yl)propoxy)-6-methoxyquinolin-4-yl)oxy)-3,5-difluorophenyl)urea as a potential anti-colorectal cancer agent

In our previous study, 1-(2-(2,6-difluorophenyl)-4-oxothiazolidin-3-yl)-3-(4-((7-(3-(4-ethylpiperazin-1-yl)propoxy)-6-methoxyquinolin-4-yl)oxy)-3,5-difluorophenyl)urea (1) was obtained as a potent tyrosine kinase inhibitor. Further structural optimization was performed in this investigation, and a series of novel quinoline derivates were designed, synthesized and evaluated for their biological activity. Among them, compound 8m possessed nanomolar c-Met and Ron inhibitory activity, with IC₅₀ values of 4.32 nM and 2.39 nM, respectively. Kinase profile study demonstrated that it could also inhibit ABL, PDGFRβ, AXL, RET, and FLT3 with submicromolar potency. It also exhibited moderate to excellent cytotoxic activity against different types of human cancer cell lines, especially against COLO 205 cells (IC₅₀ = 0.035 μM) which was remarkably superior to that of Cabozantinib (IC₅₀ = 6.6 μM) and Fruquintinib (IC₅₀ > 10.0 μM). Compared to ( ± )-8m, isomer (S)-8m and (R)-8m showed similar kinase inhibitory activity against c-Met/RON and in vitro anticancer activity against COLO 205 cells. Differently, compound (S)-8m showed an over 238-fold selectivity toward COLO 205 (IC₅₀ = 0.042 μM) cells to FHC cells (IC₅₀ > 10.0 μM), which indicated its low cytotoxicity against human normal tissue cells. Flow cytometry study demonstrated that compound (S)-8m could significantly induce apoptosis in COLO 205 cells in a dose-dependent manner. Cell cycle arrest assays showed that compound (S)-8m could not arrest the cell-cycle progression due to the massive dead cells.

KRAS and MET in non-small-cell lung cancer: two of the new kids on the 'drivers' block

Non-small-cell lung cancer (NSCLC) is a heterogeneous disease, and therapeutic management has advanced to identify various critical oncogenic mutations that promote lung cancer tumorigenesis. Subsequent studies have developed targeted therapies against these oncogenes in the hope of personalized treatment based on the tumor's molecular genomics. This review presents a comprehensive review of the biology, new therapeutic interventions, and resistance patterns of two well-defined subgroups, tumors with KRAS and MET alterations. We also discuss the status of molecular testing practices for these two key oncogenic drivers, considering the progressive introduction of next-generation sequencing (NGS) and RNA sequencing in regular clinical practice.

CCL20 induces colorectal cancer neoplastic epithelial cell proliferation, migration, and further CCL20 production through autocrine HGF-c-Met and MSP-MSPR signaling pathways

CCL20-CCR6 interactions promote colorectal cancer through direct effects on neoplastic epithelial cells and through modulating the tumor microenvironment. The mechanism of these effects on neoplastic epithelial cells is poorly understood. This study demonstrates that CCL20 induces secretion of hepatocyte growth factor (HGF) and phosphorylation of HGF’s cognate receptor c-Met in HT29 and HCT116 colorectal cancer cell lines both in concentration- and time-dependent manners. Similar to CCL20, HGF induces migration, autofeedback CCL20 secretion, and ERK1/2 phosphorylation in the colon cancer cells. CCL20-dependent ERK1/2 phosphorylation is blocked by HGF inhibition, and CCL20-dependent migration and CCL20 secretion are blocked by inhibition of HGF or ERK. Interestingly, unlike CCL20, HGF does not induce proliferation of colon cancer cells, and CCL20-dependent cell proliferation is not blocked by direct HGF inhibition. CCL20-dependent proliferation, however, is blocked by the multi-tyrosine kinase inhibitor crizotinib. Exploring this effect, it was found that CCL20 also induces production of MSP and phosphorylation of MSP’s receptor MSPR by the colorectal cancer cells. CCL20-dependent cell proliferation is inhibited by directly blocking MSP-MSPR interactions. Thus, CCL20-mediated migration and CCL20 secretion are regulated through a pathway involving HGF, c-Met, and ERK, while CCL20-mediated proliferation is instead regulated through MSP and its receptor MSPR.

Oncogenic mechanism-based pharmaceutical validation of therapeutics targeting MET receptor tyrosine kinase

Aberrant expression and/or activation of the MET receptor tyrosine kinase is characterized by genomic recombination, gene amplification, activating mutation, alternative exon-splicing, increased transcription, and their different combinations. These dysregulations serve as oncogenic determinants contributing to cancerous initiation, progression, malignancy, and stemness. Moreover, integration of the MET pathway into the cellular signaling network as an addiction mechanism for survival has made this receptor an attractive pharmaceutical target for oncological intervention. For the last 20 years, MET-targeting small-molecule kinase inhibitors (SMKIs), conventional therapeutic monoclonal antibodies (TMABs), and antibody-based biotherapeutics such as bispecific antibodies, antibody–drug conjugates (ADC), and dual-targeting ADCs have been under intensive investigation. Outcomes from preclinical studies and clinical trials are mixed with certain successes but also various setbacks. Due to the complex nature of MET dysregulation with multiple facets and underlying mechanisms, mechanism-based validation of MET-targeting therapeutics is crucial for the selection and validation of lead candidates for clinical trials. In this review, we discuss the importance of various types of mechanism-based pharmaceutical models in evaluation of different types of MET-targeting therapeutics. The advantages and disadvantages of these mechanism-based strategies for SMKIs, conventional TMABs, and antibody-based biotherapeutics are analyzed. The demand for establishing new strategies suitable for validating novel biotherapeutics is also discussed. The information summarized should provide a pharmaceutical guideline for selection and validation of MET-targeting therapeutics for clinical application in the future.

Natural Product Based Antibody Drug Conjugates: Clinical Status as of November 9, 2020

As of early November 2020, there are 10 approved antibody drug conjugates (ADCs) plus two others that are not usually listed. In addition, there are 70 ADCs at stages from phase I to phase III and 23 that are at the preclinical stage. The warheads of all of these drugs and drug candidates have their origins in natural product structures. The sources and modifications are discussed in general and then specifically commented on in each case with either the generic name if known and/or the ADC's ID names. Interestingly, almost all warheads listed are from microbial sources though initially a number were thought to have been from plants. The latest NCT numbers from Clintrials.gov of all phase I to phase III candidates are also given. Three unusual ADCs are also discussed, two of which (an antitumor agent and one directed against autoimmune diseases) are not usually listed as ADCs, with the third being an anti-infective.

Pharmaceutical strategies in the emerging era of antibody-based biotherapeutics for the treatment of cancers overexpressing MET receptor tyrosine kinase

Pharmaceutical innovation in the development of novel antibody-based biotherapeutics with increased therapeutic indexes makes MET-targeted cancer therapy a clinical reality.