Synergistic antitumor effects of cMet inhibitor in combination with anti-VEGF in colorectal cancer patient-derived xenograft models

Deciphering treatment resistance in metastatic colorectal cancer: roles of drug transports, EGFR mutations, and HGF/c-MET signaling

In 2023, colorectal cancer (CRC) is the third most diagnosed malignancy and the third leading cause of cancer death worldwide. At the time of the initial visit, 20% of patients diagnosed with CRC have metastatic CRC (mCRC), and another 25% who present with localized disease will later develop metastases. Despite the improvement in response rates with various modulation strategies such as chemotherapy combined with targeted therapy, radiotherapy, and immunotherapy, the prognosis of mCRC is poor, with a 5-year survival rate of 14%, and the primary reason for treatment failure is believed to be the development of resistance to therapies. Herein, we provide an overview of the main mechanisms of resistance in mCRC and specifically highlight the role of drug transports, EGFR, and HGF/c-MET signaling pathway in mediating mCRC resistance, as well as discuss recent therapeutic approaches to reverse resistance caused by drug transports and resistance to anti-EGFR blockade caused by mutations in EGFR and alteration in HGF/c-MET signaling pathway.

Patient-derived xenograft model in colorectal cancer basic and translational research

Colorectal cancer (CRC) is one of the most popular malignancies globally, with 930 000 deaths in 2020. The evaluation of CRC-related pathogenesis and the discovery of potential therapeutic targets will be meaningful and helpful for improving CRC treatment. With huge efforts made in past decades, the systematic treatment regimens have been applied to improve the prognosis of CRC patients. However, the sensitivity of CRC to chemotherapy and targeted therapy is different from person to person, which is an important cause of treatment failure. The emergence of patient-derived xenograft (PDX) models shows great potential to alleviate the straits. PDX models possess similar genetic and pathological characteristics as the features of primary tumors. Moreover, PDX has the ability to mimic the tumor microenvironment of the original tumor. Thus, the PDX model is an important tool to screen precise drugs for individualized treatment, seek predictive biomarkers for prognosis supervision, and evaluate the unknown mechanism in basic research. This paper reviews the recent advances in constructed methods and applications of the CRC PDX model, aiming to provide new knowledge for CRC basic research and therapeutics.

Patient-derived xenograft models for gastrointestinal tumors: A single-center retrospective study

BACKGROUND

Patient-derived xenograft (PDX) models have shown a great efficiency in preclinical and translational applications. Gastrointestinal (GI) tumors have a strong heterogeneity, and the engraftment rate of PDX models remarkably vary. However, the clinicopathological and molecular characteristics affecting the engraftment rate still remain elusive.

METHODS

A total of 312 fresh tumor tissue samples from patients with GI cancer were implanted into immunodeficient mice. The median follow-up time of patients was 37 months. Patients' characteristics were compared in terms of PDX growth and overall survival. PDX models of 3-6 generations were used for drug evaluation.

RESULTS

In total, 171 (54.8%, 171/312) PDX models were established, including 85 PDX models of colorectal cancer, 21 PDX models of esophageal cancer, and 65 PDX models of gastric cancer. Other than tumor site, histology, differentiation degree, and serum alpha-fetoprotein (AFP) level, no significant differences were found between transplantation of xenografts and patients' characteristics. For patients who had undergone neoadjuvant therapy, the incidence of tumor formation was higher in those with progressive disease (PD) or stable disease (SD). In gastric cancer, the results showed a higher transplantation rate in deficient mismatch repair (dMMR) tumors, and Ki-67 could be an important factor affecting the engraftment rate. The gene mutation status of RAS and BRAF, two important molecular markers in colorectal cancer, showed a high degree of consistency between patients' tumors and PDXs. However, no significant effects of these two mutations on PDX engraftment rate were observed. More importantly, in this study although KRAS mutations were detected in two clinical cases, evident tumor inhibition was still observed after cetuximab treatment in both PDX models and patients.

CONCLUSION

A large-scale PDX model including 171 cases was successfully established for GI tumors in our center. The relationship between clinicopathological and molecular features and engraftment rates were clarified. Furthermore, this resource provides us with profound insights into tumor heterogeneity, making these models valuable for PDX-guided treatment decisions, and offering the PDX model as a great tool for personalized treatment and translation research.

Structure-based pharmacophore mapping and virtual screening of natural products to identify polypharmacological inhibitor against c-MET/EGFR/VEGFR-2

Three receptor tyrosine kinases (RTKs), c-MET, EGFR, and VEGFR-2 have been identified as potential oncogenic targets involved in tumor development, metastasis, and invasion. Designing inhibitors that can simultaneously interact with multiple targets is a promising approach, therefore, inhibiting these three RTKs with a single chemical component might give an effective chemotherapeutic strategy for addressing the disease while limiting adverse effects. The in-silico methods have been developed to identify the polypharmacological inhibitors particularly for drug repurposing and multitarget drug design. Here, to find a viable inhibitor from natural source against these three RTKs, structure-based pharmacophore mapping and virtual screening of SN-II database were carried out. The filtered compound SN00020821, identified as Cedeodarin, from different computational approaches, demonstrated good interactions with all the three targets, c-MET/EGFR/VEGFR-2, with interaction energies of -42.35 kcal/mol, -49.32 kcal/mol and -44.83 kcal/mol, respectively. SN00020821displayed stable key interactions with critical amino acids of all the three receptors' kinase catalytic domains including "DFG motif" explored through the MD simulations. Furthermore, it also met the ADMET requirements and was determined to be drug-like as predicted from the Lipinski's rule of five and Veber's rule. Finally, SN00020821 provides a novel molecular scaffold that could be investigated further as a polypharmacological anticancer therapeutic candidate that targets the three RTKs.Communicated by Ramaswamy H. Sarma.

AZD8055 enhances in vivo efficacy of afatinib in chordomas

Chordomas are primary bone tumors that arise in the cranial base, mobile spine, and sacrococcygeal region, affecting patients of all ages. Currently, there are no approved agents for chordoma patients. Here, we evaluated the anti-tumor efficacy of small molecule inhibitors that target oncogenic pathways in chordoma, as single agents and in combination, to identify novel therapeutic approaches with the greatest translational potential. A panel of small molecule compounds was screened in vivo against patient-derived xenograft (PDX) models of chordoma, and potentially synergistic combinations were further evaluated using chordoma cell lines and xenograft models. Among the tested agents, inhibitors of EGFR (BIBX 1382, erlotinib, and afatinib), c-MET (crizotinib), and mTOR (AZD8055) significantly inhibited tumor growth in vivo but did not induce tumor regression. Co-inhibition of EGFR and c-MET using erlotinib and crizotinib synergistically reduced cell viability in chordoma cell lines but did not result in enhanced in vivo activity. Co-inhibition of EGFR and mTOR pathways using afatinib and AZD8055 synergistically reduced cell viability in chordoma cell lines. Importantly, this dual inhibition completely suppressed tumor growth in vivo, showing improved tumor control. Together, these data demonstrate that individual inhibitors of EGFR, c-MET, and mTOR pathways suppress chordoma growth both in vitro and in vivo. mTOR inhibition increased the efficacy of EGFR inhibition on chordoma growth in several preclinical models. The insights gained from our study potentially provide a novel combination therapeutic strategy for patients with chordoma. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Combination of HGF/MET-targeting agents and other therapeutic strategies in cancer

MET receptor has emerged as a druggable target across several human cancers. Agents targeting MET and its ligand hepatocyte growth factor (HGF) including small molecules such as crizotinib, tivantinib and cabozantinib or antibodies including rilotumumab and onartuzumab have proven their values in different tumors. Recently, capmatinib was approved for treatment of metastatic lung cancer with MET exon 14 skipping. In this review, we critically examine the current evidence on how HGF/MET combination therapies may take advantage of synergistic effects, overcome primary or acquired drug resistance, target tumor microenvironment, modulate drug metabolism or tackle pharmacokinetic issues. Preclinical and clinical studies on the combination of HGF/MET-targeted agents with conventional chemotherapeutics or molecularly targeted treatments (including EGFR, VEGFR, HER2, RAF/MEK, and PI3K/Akt targeting agents) and also the value of biomarkers are examined. Our deeper understanding of molecular mechanisms underlying successful pharmacological combinations is crucial to find the best personalized treatment regimens for cancer patients.

MET Inhibitors for the Treatment of Gastric Cancer: What's Their Potential?

Gastric cancer remains a disease with a dismal prognosis. Extensive efforts to find targetable disease drivers in gastric cancer were implemented to improve patient outcomes. Beyond anti-HER2 therapy, MET pathway seems to be culprit of cancer invasiveness with MET-overexpressing tumors having poorer prognosis. Tyrosine kinase inhibitors targeting the HGF/MET pathway were studied in MET-positive gastric cancer, but no substantial benefit was proven. Some patients responded in early phase trials but later developed resistance. Others failed to show any benefit at all. Etiologies of resistance may entail inappropriate patient selection with a lack of MET detection standardization, tumor alternative pathways, variable MET amplification, and genetic variation. Optimizing MET detection techniques and better understanding the MET pathway, as well as tumor bypass mechanisms, are an absolute need to devise means to overcome resistance using targeted therapy alone, or in combination with other synergistic agents to improve outcomes of patients with MET-positive GC.

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.

Bevacizumab combined with apatinib enhances antitumor and anti-angiogenesis effects in a lung cancer model in vitro and in vivo

Angiogenesis is involved in the proliferation and metastasis of solid tumours; hence, it is an attractive therapeutic target. However, most patients who undergo anti-angiogenic drug treatment do not achieve complete tumour regression, resulting in drug resistance. The objective of this research is to explore the therapeutic effect of combining bevacizumab (Bev), an anti-vascular endothelial growth factor (VEGF)-A antibody, with apatinib (Apa), a VEGR receptor (VEGFR)-2-targeting tyrosine kinase inhibitor, in non-small cell lung cancer (NSCLC). In vitro, we assessed the influence which Bev + Apa treatment exerts upon the proliferation as well as apoptosis of Lewis lung carcinoma (LLC) cells in virtue of the 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide as assay as well as Annexin V staining, respectively. For in vivo assessment, we established a tumour-bearing mouse model with LLC cells and investigated the anti-angiogenic and antitumor effects of Bev + Apa by ¹⁸F-FDG PET/CT imaging, immunohistochemistry and TUNEL staining. Bev + Apa treatment significantly inhibited LLC cell growth and proliferation in a larger scale compared to therapy of either of the only agent. Bev + Apa inhibited tumour growth and extended the median survival time of tumour-bearing mice. Mechanistically, Bev + Apa reduced angiogenesis by inhibiting VEGF and VEGFR-2 expression and reducing glucose metabolism in tumour tissues. Thus, Bev and Apa inhibited tumour angiogenesis synergistically, indicating their potential clinical utility for NSCLC treatment.

Apatinib as targeted therapy for advanced bone and soft tissue sarcoma: a dilemma of reversing multidrug resistance while suffering drug resistance itself

Bone and soft tissue sarcomas are rare malignant tumors originated from mesenchymal tissues. They harbor more than 50 distinct subtypes and differ in pathological features and clinical courses. Despite the significant improvements in modern multi-modality treatment, the outcomes and overall survival rates remain poor for patients with advanced, refractory, metastatic, or relapsed diseases. The growth and metastasis of bone and soft tissue sarcoma largely depend on angiogenesis, and VEGF/VEGFR pathway is considered as the most prominent player in angiogenesis. Therefore, blockade of VEGF/VEGFR pathways is a promising therapeutic strategy to retard neovascularization. Several VEGFR inhibitors have been developed and revealed their favorable anti-neoplastic effects in various cancers, but such desirable anti-tumor effects are not obtained in advanced sarcomas because of multiple reasons, such as drug tolerance, short duration of response, and severe adverse effects. Fortunately, preclinical and clinical studies have indicated that apatinib is a novel promising VEGFR2 inhibitor showing potent anti-angiogenic and anti-neoplastic activities in advanced sarcomas. Especially, apatinib has showed notable characteristics in multidrug resistance reversal, tumor regression, vascular normalization, immunosuppression alleviation, and enhancement of chemotherapeutic and radiotherapeutic effects. However, apatinib also gets struck in dilemma of reversing multidrug resistance of chemotherapeutic agents while suffering drug resistance itself, and several difficulties should be tackled before full use of apatinib. In this review, we discuss the outstanding characteristics and main predicaments of apatinib as targeted therapy in advanced sarcomas. Bone and soft tissue sarcomas are rare but malignant tumors originated from mesenchymal tissues. They harbor more than 100 distinct subtypes and differ in features of pathologies and clinical courses. Despite the significant improvements in modern multi-modality treatment, the outcomes and overall survival rates remain poor for patients with advanced, refractory, metastatic, or relapsed lesions. The growth and metastasis of bone and soft tissue sarcoma largely depend on angiogenesis and VEGF/VEGFR pathways play a pivotal role in angiogenesis. Therefore, blockade of VEGF/VEGFR pathways is a promising therapeutic strategy. Several VEGFR inhibitors have been developed and verified in clinical trials but with unfavorable outcomes. Fortunately, preclinical studies and clinical trials have indicated that apatinib is a novel promising VEGFR2 inhibitor showing potent anti-angiogenic and anti-neoplastic activities in advanced sarcomas. Actually, apatinib has showed notable characteristics in multidrug resistance reversal, tumor regression, vascular normalization, immunosuppression alleviation, enhancement of chemotherapeutic and radiotherapeutic effects. However, apatinib also gets struck in dilemma of reversing multidrug resistance of chemotherapeutic agents while suffering drug resistance itself, and several difficulties should be tackled before full use of apatinib. In this review, we discuss the outstanding characteristics and main predicaments of apatinib as targeted therapy in advanced sarcomas.

Therapeutic targeting of the crosstalk between cancer-associated fibroblasts and cancer stem cells

Cancer-associated fibroblasts (CAFs) play critical roles in cancer progression and treatment failure. CAFs display extreme phenotypic heterogeneity and functional diversity. Some subpopulations of CAFs have the ability to reconstitute cancer stemness by promoting the expansion of cancer stem cells (CSCs) or by inducing the generation of CSCs from differentiated cancer cells. CAFs regulate cancer stemness in different types of solid tumors by activating a wide array of CSC-related signaling by secreting proteins and exosomes. As feedback, the CSCs can also induce the proliferation and further activation of CAFs to promote their CSC-supporting activities, thus completing the loop of CAF-CSC crosstalk. Current research on targeting CAF-CSC crosstalk could be classified into (i) specific depletion of CAF subpopulations that have CSC-supporting activities and (ii) targeting molecular signaling in CAF-CSC crosstalk, such as the IL6/STAT3, TGF-β/SDF-1/PI3K, WNT/β-catenin, HGF/cMET and SHH/Hh pathways. Strategies targeting CAF-CSC crosstalk may open new avenues for overcoming cancer progression and therapeutic resistance.

Grape seed procyanidin B2 promotes the autophagy and apoptosis in colorectal cancer cells via regulating PI3K/Akt signaling pathway

Aim: Colorectal cancer (CRC) is a major malignancy in China, which is the critical risk of people health. Many natural herbs extracts have been found to exhibit good therapeutic effect on CRC. Our previous study found that grape seed procyanidins B2 (PB2) would induce CRC cell death. However, the molecular mechanism underlying its anti-tumor effect on CRC remains unclear. Thereby, this study aimed to investigate the anti-tumor mechanism of PB2 on CRC.

Methods: CCK-8, western blotting, flow cytometry, qRT-PCR and animal study were used in the current study.

Results: The in vitro and in vivo data demonstrated that PB2 could promote the apoptosis of CRC cells in a dose-dependent manner, which was significantly reversed by caspase 3 inhibitor. Meanwhile, PB2 dose-dependently induced autophagy in CRC cells, which was markedly attenuated by autophagy inhibitor 3-MA. In addition, PB2 dose-dependently inhibited the expressions of p-PI3K, p-Akt and p-mTOR in the cells.

Conclusion: PB2 dose-dependently induced apoptosis and autophagy in CRC cells via downregulation of PI3K/Akt pathway. This study provided the experimental basis for further development of PB2 as a new effective anticancer drug for the patients with CRC.