Phase I trial of a selective c-MET inhibitor ARQ 197 incorporating proof of mechanism pharmacodynamic studies

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.

Circulating tumor cells in pancreatic cancer: more than liquid biopsy

Circulating tumor cells (CTCs) are tumor cells that slough off the primary lesions and extravasate into the bloodstream. By forming CTC clusters and interacting with other circulating cells (platelets, NK cells, macrophage, etc.), CTCs are able to survive in the circulatory system of tumor patients and colonize to metastatic organs. In recent years, the potential of CTCs in diagnosis, prognostic assessment, and individualized therapy of various types of tumors has been gradually explored, while advances in biotechnology have made it possible to extract CTCs from patient blood samples. These biological features of CTCs provide us with new insights into cancer vulnerabilities. With the advent of new immunotherapies and personalized medicines, disrupting the heterotypical interaction between CTCs and circulatory cells as well as direct CTCs targeting hold great promise. Pancreatic cancer (PC) is one of the most malignant cancers, in part because of early metastasis, difficult diagnosis, and limited treatment options. Although there is significant potential for CTCs as a biomarker to impact PC from diagnosis to therapy, there still remain a number of challenges to the routine implementation of CTCs in the clinical management of PC. In this review, we summed up the progress made in understanding biological characteristics and exceptional technological advances of CTCs and provided insight into exploiting these developments to design future clinical tools for improving the diagnosis and treatment of PC.

Targeted therapies in hepatocellular carcinoma: past, present, and future

Targeted therapies are the mainstay of systemic therapies for patients with advanced, unresectable, or metastatic hepatocellular carcinoma. Several therapeutic targets, such as c-Met, TGF-β, and FGFR, have been evaluated in the past, though results from these clinical studies failed to show clinical benefit. However, these remain important targets for the future with novel targeted agents and strategies. The Wnt/β-catenin signaling pathway, c-Myc oncogene, GPC3, PPT1 are exciting novel targets, among others, currently undergoing evaluation. Through this review, we aim to provide an overview of previously evaluated and potentially novel therapeutic targets and explore their continued relevance in ongoing and future studies for HCC.

Bmi-1: A master regulator of head and neck cancer stemness

Head and neck cancers are composed of a diverse group of malignancies, many of which exhibit an unacceptably low patient survival, high morbidity and poor treatment outcomes. The cancer stem cell (CSC) hypothesis provides an explanation for the substantial patient morbidity associated with treatment resistance and the high frequency of tumor recurrence/metastasis. Stem cells are a unique population of cells capable of recapitulating a heterogenous organ from a single cell, due to their capacity to self-renew and differentiate into progenitor cells. CSCs share these attributes, in addition to playing a pivotal role in cancer initiation and progression by means of their high tumorigenic potential. CSCs constitute only a small fraction of tumor cells but play a major role in tumor initiation and therapeutic evasion. The shift towards stem-like phenotype fuels many malignant features of a cancer cell and mediates resistance to conventional chemotherapy. Bmi-1 is a master regulator of stem cell self-renewal as part of the polycomb repressive complex 1 (PRC1) and has emerged as a prominent player in cancer stem cell biology. Bmi-1 expression is upregulated in CSCs, which is augmented by tumor-promoting factors and various conventional chemotherapies. Bmi-1⁺ CSCs mediate chemoresistance and metastasis. On the other hand, inhibiting Bmi-1 rescinds CSC function and re-sensitizes cancer cells to chemotherapy. Therefore, elucidating the functional role of Bmi-1 in CSC-mediated cancer progression may unveil an attractive target for mechanism-based, developmental therapeutics. In this review, we discuss the parallels in the role of Bmi-1 in stem cell biology of health and disease and explore how this can be leveraged to advance clinical treatment strategies for head and neck cancer.

Phase 1 Study of the Selective c-MET Inhibitor, HS-10241, in Patients With Advanced Solid Tumors

Introduction

c-MET is an important therapeutic target for various cancers; however, the People's Republic of China currently retails only one specific c-MET inhibitor. Our preclinical study has revealed the high selectivity of HS-10241 to suppress c-MET. This phase 1 study aims to evaluate the safety, tolerability, pharmacokinetics, and antitumor activity of the selective c-MET inhibitor (HS-10241) in patients with advanced solid tumors.

Methods

Patients with locally advanced or metastatic solid tumors orally received a single or multiple dose of HS-10241 once daily or twice daily for 21 consecutive days, which included the following six regimens: 100 mg once daily, 200 mg once daily, 400 mg once daily, 600 mg once daily, 200 mg twice daily, and 300 mg twice daily. The treatment continued until disease progression, unacceptable toxicity, or treatment termination. The primary end point was the incidence of dose-limiting toxicity and maximal tolerated dose (MTD). Secondary end points included safety, tolerability, pharmacokinetics, and pharmacodynamics.

Results

A total of 27 patients with advanced NSCLC received HS-10241, and dose-limiting toxicity was observed in three patients after 600 mg once-daily HS-10241 treatment. For once-daily dosing, MTD was 400 mg, and for twice-daily dosing, the maximal safe escalated dose was 300 mg, and MTD was not reached. Nausea (48.1%, 13 of 27), fatigue (37.0%, 10 of 27), and anemia (33.3%, 9 of 27) are the three most frequent treatment-emergent adverse events. At 400 mg once daily, C_ss,max was 5076 ng/mL and steady state area under the curve was 39,998 h × ng/mL. Patients (n = 5) with positive MET (MET exon 14-skipping, MET amplified, and MET immunohistochemistry 3+) had confirmed partial responses (n = 1) or stable disease (n = 3), with a disease control rate of 80.0%.

Conclusions

The selective c-MET inhibitor HS-10241 was well tolerated and had clinical activity in advanced NSCLC, especially in patients with positive MET. Furthermore, this study expounds on the therapeutic potential of HS-10241 in patients with cancer.

EGFR/MET promotes hepatocellular carcinoma metastasis by stabilizing tumor cells and resisting to RTKs inhibitors in circulating tumor microemboli

The receptor tyrosine kinases (RTKs) family is well-recognized as vital targets for the treatment of hepatocarcinoma cancer (HCC) clinically, whereas the survival benefit of target therapy sorafenib is not satisfactory for liver cancer patients due to metastasis. EGFR and MET are two molecules of the RTK family that were related to the survival time of liver cancer patients and resistance to targeted therapy in clinical reports. However, the mechanism and clinical therapeutic value of EGFR/MET in HCC metastasis are still not completely clarified. The study confirmed that EGFR/MET was highly expressed in HCC cells and tissues and the phosphorylation was stable after metastasis. The expression of EGFR/MET was up-regulated in circulating tumor microemboli (CTM) to accelerate IL-8 production and resistance to the lethal effect of leukocytes. Meanwhile, highly expressed EGFR/MET effectively regulated the Ras/MAPK pathway and stabilized suspended HCC cells by facilitating proliferation and inhibiting apoptosis. Moreover, EGFR/MET promoted phosphorylation of hetero-RTKs, which was dependent on high-energy phosphoric acid compounds rather than their direct interactions. In conclusion, highly expressed EGFR/MET could be used in CTM identification and suitable for preventing metastasis of HCC in clinical practice.

Pharmacogenomics Testing in Phase I Oncology Clinical Trials: Constructive Criticism Is Warranted

Simple Summary

Phase I clinical trials are a cornerstone of pharmaceutical development in oncology. Many studies have now attempted to incorporate pharmacogenomics into phase I studies; however, many of these studies have fundamental flaws that that preclude interpretation and application of their findings. Study populations are often small and heterogeneous with multiple disease states, multiple dose levels, and prior therapies. Genetic testing typically includes few variants in candidate genes that do no encapsulate the full range of phenotypic variability in protein function. Moreover, a plurality of these studies do not present scientifically robust clinical or preclinical justification for undertaking pharmacogenomics studies. A significant amount of progress in understanding pharmacogenomic variability has occurred since pharmacogenomics approaches first began appearing in the literature. This progress can be immediately leveraged for the vast majority of Phase I studies. The purpose of this review is to summarize the current literature pertaining to Phase I incorporation of pharmacogenomics studies, analyze potential flaws in study design, and suggest approaches that can improve design of future scientific efforts.

Abstract

While over ten-thousand phase I studies are published in oncology, fewer than 1% of these studies stratify patients based on genetic variants that influence pharmacology. Pharmacogenetics-based patient stratification can improve the success of clinical trials by identifying responsive patients who have less potential to develop toxicity; however, the scientific limits imposed by phase I study designs reduce the potential for these studies to make conclusions. We compiled all phase I studies in oncology with pharmacogenetics endpoints (n = 84), evaluating toxicity (n = 42), response or PFS (n = 32), and pharmacokinetics (n = 40). Most of these studies focus on a limited number of agent classes: Topoisomerase inhibitors, antimetabolites, and anti-angiogenesis agents. Eight genotype-directed phase I studies were identified. Phase I studies consist of homogeneous populations with a variety of comorbidities, prior therapies, racial backgrounds, and other factors that confound statistical analysis of pharmacogenetics. Taken together, phase I studies analyzed herein treated small numbers of patients (median, 95% CI = 28, 24–31), evaluated few variants that are known to change phenotype, and provided little justification of pharmacogenetics hypotheses. Future studies should account for these factors during study design to optimize the success of phase I studies and to answer important scientific questions.

Efficacy and Safety of Second-line Treatments in Patients with Advanced Hepatocellular Carcinoma after Sorafenib Failure: A Meta-analysis

BACKGROUND AND AIMS

In the last decade, several second-line therapies followed by sorafenib in patients with advanced hepatocellular carcinoma (HCC) have been reported. But the outcomes were different from each other. This meta-analysis aimed to evaluate the efficacy and safety of the second-line therapies followed by sorafenib in patients with advanced HCC.

METHODS

Embase (1974 to October 2019) and Ovid MEDLINE (1946 to October 2019) were searched for randomized clinical trials on second-line therapies followed by sorafenib in patients with advanced HCC. The quality of each study was assessed by the modified Jadad scale. Statistical analysis was carried out by RevMan5.3 software. Efficacy and safety were analyzed. Efficacy included overall survival (OS), disease control rate, time to progression, and progression-free survival.

RESULTS

Eight studies involving 3,173 patients were eligible. No difference in OS was found between the second-line treatment group and the control group (HR=0.87, 95% CI: 0.74-1.01, p=0.06). Disease control rate (relative risk (RR)=1.36, 95% CI: 1.16-1.60, p=0.0002), time to progression (HR=0.64, 95% CI: 0.51-0.81, p=0.0002) and progression-free survival (HR=0.60, 95% CI: 0.46-0.77, p<0.0001) were significantly improved by the second-line therapies. There was a slight difference in adverse events of any grade (RR=1.07, 95% CI: 1.00-1.14, p=0.03) between the two groups.

CONCLUSIONS

These second-line therapies followed by sorafenib may potentially improve the prognosis in patients with advanced HCC. Compared with other second-line therapies, regorafenib seemed to be more effective.

Association between the HGF/c‑MET signaling pathway and tumorigenesis, progression and prognosis of hepatocellular carcinoma (Review)

Hepatocellular carcinoma (HCC) is one of the most aggressive and lethal malignancies with a rising incidence, and is characterized by rapid progression, frequent metastasis, late diagnosis, high postoperative recurrence and poor prognosis. Therefore, novel treatment strategies for HCC, particularly advanced HCC, are urgently required. The hepatocyte growth factor (HGF)/c‑mesenchymal‑epithelial transition receptor (c‑MET) axis is a key signaling pathway in HCC and is strongly associated with its highly malignant features. Available treatments based on HGF/c‑MET inhibition may prolong the lifespan of patients with HCC; however, they do not achieve the desired therapeutic effects. The aim of the present article was to review the basic knowledge regarding the role of the HGF/c‑MET signaling pathway in HCC, and examine the association between the HGF/c‑MET signaling pathway and the tumorigenesis, progression and prognosis of HCC.

Circulating tumor cell profiling for precision oncology

Analysis of circulating tumor cells (CTCs) collected from patient's blood offers a broad range of opportunities in the field of precision oncology. With new advances in profiling technology, it is now possible to demonstrate an association between the molecular profiles of CTCs and tumor response to therapy. In this Review, we discuss mechanisms of tumor resistance to therapy and their link to phenotypic and genotypic properties of CTCs. We summarize key technologies used to isolate and analyze CTCs and discuss recent clinical studies that examined CTCs for genomic and proteomic predictors of responsiveness to therapy. We also point out current limitations that still hamper the implementation of CTCs into clinical practice. We finally reflect on how these shortcomings can be addressed with the likely contribution of multiparametric approaches and advanced data analytics.

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.

Dual Blockade of c-MET and the Androgen Receptor in Metastatic Castration-resistant Prostate Cancer: A Phase I Study of Concurrent Enzalutamide and Crizotinib

PURPOSE

Androgen receptor (AR) inhibition can upregulate c-MET expression, which may be a resistance mechanism driving progression of castration-resistant prostate cancer (CRPC). We conducted a phase I trial investigating the safety and pharmacokinetics of a potent c-MET inhibitor, crizotinib, with the AR antagonist, enzalutamide, in CRPC.

PATIENTS AND METHODS

Employing a 3+3 dose-escalation design, we tested three dose levels of crizotinib (250 mg daily, 200 mg twice a day, and 250 mg twice a day) with standard-dose enzalutamide (160 mg daily). The primary endpoint was rate of dose-limiting toxicities (DLTs). Tolerability and pharmacokinetics profile were secondary endpoints.

RESULTS

Twenty-four patients were enrolled in the dose-escalation (n = 16) and dose-expansion (n = 8) phases. Two DLTs occurred in dose escalation (grade 3 alanine aminotransferase elevation). The MTD of crizotinib was 250 mg twice a day. Most frequent treatment-related adverse events were fatigue (50%), transaminitis (38%), nausea (33%), and vomiting, constipation, and diarrhea (21% each). Grade ≥3 events (25%) included transaminitis (n = 2), fatigue (n = 1), hypertension (n = 1), pulmonary embolism (n = 1), and a cardiac event encompassing QTc prolongation/ventricular arrhythmia/cardiac arrest. Median progression-free survival was 5.5 months (95% confidence interval, 2.8-21.2). Pharmacokinetics analysis at the MTD (n = 12) revealed a mean C _max ^ss of 104 ± 45 ng/mL and AUC_τ ^ss of 1,000 ± 476 ng•h/mL, representing a 74% decrease in crizotinib systemic exposure relative to historical data (C _max ^ss, 315 ng/mL and AUC_τ ^ss, 3,817 ng•h/mL).

CONCLUSIONS

Concurrent administration of enzalutamide and crizotinib resulted in a clinically significant 74% decrease in systemic crizotinib exposure. Further investigation of this combination in CRPC is not planned. Our results highlight the importance of evaluating pharmacokinetics interactions when evaluating novel combination strategies in CRPC.

Tivantinib inhibits the VEGF signaling pathway and induces apoptosis in gastric cancer cells with c-MET or VEGFA amplification

Tivantinib has been described as a selective inhibitor of c-Met and is being studied in various types of cancer. In this study, we evaluated the effects of tivantinib on the suppression of gastric cancer (GC) cell migration and apoptosis. We also examined the mechanism of action of tivantinib by oncogenic pathway analysis. We applied an RNA-sequencing approach in 34 GC patients to identify oncogenes that are differentially expressed in GC tissues. To examine the inhibitory effect of tivantinib on GC cells, we conducted apoptosis analysis using an annexin V-APC/PI apoptosis detection kit and trans-well migration assay with human GC cell lines. For oncogenic pathway analysis, Western blot and quantitative real-time PCR analysis were used to detect the expression of proteins and genes before and after tivantinib exposure. In the RNA-sequencing analysis of 34 GC patients, c-Met and VEGFA genes were expressed and positively correlated with each other. Cell migration and apoptosis analysis demonstrated that tivantinib induced the best inhibition effect in SNU620, MKN45 (carries VEGFB mutation), AGS, and MKN28 cells, but not in KATO III (carries VEGFB and VEGFC mutations) cells. Oncogenic pathway analysis showed that tivantinib, in addition to c-Met signaling pathway inhibition, also inhibits VEGF signaling and MYC expression in VEGFA-expressing GC cells. We found that tivantinib has anti-cancer activity not only in GC cells overexpressing c-Met but also in non-c-Met GC cells by inhibition of the VEGF signaling pathway.

A randomized phase 2 network trial of tivantinib plus cetuximab versus cetuximab in patients with recurrent/metastatic head and neck squamous cell carcinoma

BACKGROUND

MET signaling is a well described mechanism of resistance to anti-EGFR therapy, and MET overexpression is common in head and neck squamous cell carcinomas (HNSCCs). In the current trial, the authors compared the oral MET inhibitor tivantinib (ARQ197) in combination with cetuximab (the TC arm) versus a control arm that received cetuximab monotherapy (C) in patients with recurrent/metastatic HNSCC.

METHODS

In total, 78 evaluable patients with cetuximab-naive, platinum-refractory HNSCC were enrolled, including 40 on the TC arm and 38 on the C arm (stratified by human papillomavirus [HPV] status). Patients received oral tivantinib 360 mg twice daily and intravenous cetuximab 500 mg/m² once every 2 weeks. The primary outcome was the response rate (according to Response Evaluation Criteria in Solid Tumors, version 1.1), and secondary outcomes included progression-free and overall survival. After patients progressed on the C arm, tivantinib monotherapy was optional.

RESULTS

The response rate was 7.5% in the TC arm (N = 3; 1 complete response) and 7.9% in the C arm (N = 3; not significantly different [NS]). The median progression-free survival in both arms was 4 months (NS), and the median overall survival was 8 months (NS). Both treatments were well tolerated, with a trend toward increased hematologic toxicities in the TC arm (12.5% had grade 3 leukopenia). The response rate in 31 HPV-positive/p16-positive patients was 0% in both arms, whereas the response rate in HPV-negative patients was 12.7% (12.5% in the TC arm and 13% in the C arm). Fifteen patients received tivantinib monotherapy, and no responses were observed.

CONCLUSIONS

Combined tivantinib plus cetuximab does not significantly improve the response rate or survival compared with cetuximab alone but does increase toxicity in an unselected HNSCC population. Cetuximab responses appear to be limited to patients who have HPV-negative HNSCC. MET-aberration-focused trials for HNSCC and the use of higher potency, selective MET inhibitors remain of interest.

Prediction of active human dose: learnings from 20 years of Merck KGaA experience, illustrated by case studies

High-quality dose predictions based on a good understanding of target engagement is one of the main translational goals in drug development. Here, we systematically evaluate active human dose predictions for 15 Merck KGaA/EMD Serono assets spanning several modalities and therapeutic areas. Using case studies, we illustrate the value of adhering to the translational best practices of having an exposure-response relationship in an appropriate animal model; having validated, translatable pharmacodynamic (PD) biomarkers measurable in Phase I populations in the right tissue; having a deeper understanding of biology; and capturing uncertainties in predictions. Given the gap in publications on the subject, we believe that the learnings from this unique diverse data set, which are generic to the industry, will trigger actions to improve future predictions.

Targeting cancer stem cells in squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a highly aggressive tumor and the sixth most common cancer worldwide. Current treatment strategies for HNSCC are surgery, radiotherapy, chemotherapy, immunotherapy or combinatorial therapies. However, the overall 5-year survival rate of HNSCC patients remains at about 50%. Cancer stem cells (CSCs), a small population among tumor cells, are able to self-renew and differentiate into different tumor cell types in a hierarchical manner, similar to normal tissue. In HNSCC, CSCs are proposed to be responsible for tumor initiation, progression, metastasis, drug resistance, and recurrence. In this review, we discuss the molecular and cellular characteristics of CSCs in HNSCC. We summarize current approaches used in the literature for identification of HNSCC CSCs, and mechanisms required for CSC regulation. We also highlight the role of CSCs in treatment failure and therapeutic targeting options for eliminating CSCs in HNSCC.

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.

Off-target based drug repurposing opportunities for tivantinib in acute myeloid leukemia

GSK3α has been identified as a new target in the treatment of acute myeloid leukemia (AML). However, most GSK3 inhibitors lack specificity for GSK3α over GSK3β and other kinases. We have previously shown in lung cancer cells that GSK3α and to a lesser extent GSK3β are inhibited by the advanced clinical candidate tivantinib (ARQ197), which was designed as a MET inhibitor. Thus, we hypothesized that tivantinib would be an effective therapy for the treatment of AML. Here, we show that tivantinib has potent anticancer activity across several AML cell lines and primary patient cells. Tivantinib strongly induced apoptosis, differentiation and G2/M cell cycle arrest and caused less undesirable stabilization of β-catenin compared to the pan-GSK3 inhibitor LiCl. Subsequent drug combination studies identified the BCL-2 inhibitor ABT-199 to synergize with tivantinib while cytarabine combination with tivantinib was antagonistic. Interestingly, the addition of ABT-199 to tivantinib completely abrogated tivantinib induced β-catenin stabilization. Tivantinib alone, or in combination with ABT-199, downregulated anti-apoptotic MCL-1 and BCL-XL levels, which likely contribute to the observed synergy. Importantly, tivantinib as single agent or in combination with ABT-199 significantly inhibited the colony forming capacity of primary patient AML bone marrow mononuclear cells. In summary, tivantinib is a novel GSK3α/β inhibitor that potently kills AML cells and tivantinib single agent or combination therapy with ABT-199 may represent attractive new therapeutic opportunities for AML.

A phase I trial of topotecan plus tivantinib in patients with advanced solid tumors

PURPOSE

Tyrosine kinase inhibitors (TKI) that target MET signaling have shown promise in various types of cancer, including lung cancer. Combination strategies have been proposed and developed to increase their therapeutic index. Based on preclinical synergy between inhibition of MET and topoisomerase I, a phase I study was designed to explore the combination of topotecan with the MET TKI tivantinib.

METHODS

Eligible patients with advanced solid malignancies for which there was no known effective treatment received topotecan at doses of 1.0-1.5 mg/m²/day for five consecutive days in 21-day cycles with continuous, oral tivantinib given at escalating doses of 120-360 mg orally twice daily. Pharmacokinetic analyses of tivantinib were included. Circulating tumor cells (CTC) were collected serially to identify peripheral changes in MET phosphorylation.

RESULTS

The trial included 18 patients, 17 of whom received treatment. At the planned doses, the combination of topotecan and tivantinib was not tolerable due to thrombocytopenia and neutropenia. The addition of G-CSF to attenuate neutropenia did not improve tolerability. Greater tivantinib exposure, assessed through pharmacokinetic analysis, was associated with greater toxicity. No responses were seen. MET phosphorylation was feasible in CTC, but no changes were seen with therapy.

CONCLUSIONS

The combination of topotecan and oral tivantinib was not tolerable in this patient population.

Utility of rapid on-site evaluation for needle core biopsies and fine-needle aspiration cytology done for diagnosis of mass lesions of the liver

BACKGROUND

Fine-needle aspiration (FNA) and core biopsy (CB) are used to diagnose liver lesions. Rapid onsite evaluation (ROSE) can improve the adequacy of the procedures and help triage diagnostic material appropriately. There are very few studies evaluating the role of ROSE for CB and FNA of mass lesions of the liver.

METHODS

Liver cases with ROSE material from 2007 to 2017 were retrieved and reviewed. The ROSE material was re-evaluated by 2 cytopathologists who were blinded to the final diagnosis. Data including age, number of lesions, number of passes, adequacy assessed at time of procedure, and diagnosis made by cytopathologist on ROSE material at time of re-review was compiled.

RESULTS

A total of 82 cases were identified; 33 were primary lesions (group A) and 49 were metastatic lesions (group B). ROSE done by cytotechnologist at time of procedure showed an adequacy rate of 84%. During re-review of ROSE material by cytopathologists, the overall adequacy rates were similar, although the adequacy rates in group B increased (to 100% from 92%) and it dropped in group A (from 73% to 52%). The overall accuracy rate was 90%. Hepatocellular adenoma, regenerative nodules, well-differentiated hepatocellular carcinoma, and angiosarcoma were not possible to diagnose on smears alone during ROSE.

CONCLUSIONS

ROSE for liver lesions is useful for assessing adequacy. Certain lesions cannot be accurately diagnosed on ROSE alone. ROSE material when assessed by cytopathologist can improve adequacy rate and possibly decrease number of nondiagnostic specimens in group A, though the cost effectiveness needs to be assessed.

Phase II randomized, double-blind, placebo-controlled study of tivantinib in men with asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer (mCRPC)

Background Tivantinib is a non-ATP competitive inhibitor of c-MET receptor tyrosine kinase that may have additional cytotoxic mechanisms including tubulin inhibition. Prostate cancer demonstrates higher c-MET expression as the disease progresses to more advanced stages and to a castration resistant state. Methods 80 patients (pts) with asymptomatic or minimally symptomatic mCRPC were assigned (2:1) to either tivantinib 360 mg PO BID or placebo (P). The primary endpoint was progression free survival (PFS). Results Of the 80 pts. enrolled, 78 (52 tivantinib, 26 P) received treatment and were evaluable. Median follow up is 8.9 months (range: 2.3 to 19.6 months). Patients treated with tivantinib had significantly better PFS vs. those treated with placebo (medians: 5.5 mo vs 3.7 mo, respectively; HR = 0.55, 95% CI: 0.33 to 0.90; p = 0.02). Grade 3 febrile neutropenia was seen in 1 patient on tivantinib while grade 3 and 4 neutropenia was recorded in 1 patient each on tivantinib and placebo. Grade 3 sinus bradycardia was recorded in two men on the tivantinib arm. Conclusions Tivantinib has mild toxicity and improved PFS in men with asymptomatic or minimally symptomatic mCRPC.

New targeted therapies for adrenocortical carcinomas

Adrenocortical carcinoma (ACC) is a rare malignancy with poor prognosis. It has undergone in-depth clinical and laboratory investigations, with the help of the most important research groups all over the world. Nonetheless the cure for this kind of neoplasia is not right around the corner, given its complexity and multi-faceted feature, that lead researchers to think at "one person one ACC." Currently total resection is the most concrete option for ACC patients, whenever possible. Mitotane remains the main drug for primary or adjuvant therapy, but gives partial and unsatisfactory therapeutic results, especially in metastatic ACC. This prompted the researchers to find other ways to fight against this malignancy: targeted therapy seems the most promising answer, as it is based on biomolecular and genetic cancer signature. Numerous specific targets were explored for the treatment of ACC, such as those involving angiogenesis, steroidogenesis, Wnt/β-catenin pathway and many others key factors. Even if large efforts have been made, no effective target therapy entered in the clinical use. This data should not be considered only as detrimental, rather it should propel scientific research to invest more resources into the therapeutic exploration of ACC and in particular on the most promising strategy, the targeted therapy.

Tivantinib for second-line treatment of MET-high, advanced hepatocellular carcinoma (METIV-HCC): a final analysis of a phase 3, randomised, placebo-controlled study

BACKGROUND

Tivantinib (ARQ 197), a selective, oral MET inhibitor, improved overall survival and progression-free survival compared with placebo in a randomised phase 2 study in patients with high MET expression (MET-high) hepatocellular carcinoma previously treated with sorafenib. The aim of this phase 3 study was to confirm the results of the phase 2 trial.

METHODS

We did a phase 3, randomised, double-blind, placebo-controlled study in 90 centres in Australia, the Americas, Europe, and New Zealand. Eligible patients were 18 years or older and had unresectable, histologically confirmed, hepatocellular carcinoma, an Eastern Cooperative Oncology Group performance status of 0-1, high MET expression (MET-high; staining intensity score ≥2 in ≥50% of tumour cells), Child-Pugh A cirrhosis, and radiographically-confirmed disease progression after receiving sorafenib-containing systemic therapy. We randomly assigned patients (2:1) in block sizes of three using a computer-generated randomisation sequence to receive oral tivantinib (120 mg twice daily) or placebo (twice daily); patients were stratified by vascular invasion, extrahepatic spread, and α-fetoprotein concentrations (≤200 ng/mL or >200 ng/mL). The primary endpoint was overall survival in the intention-to-treat population. Efficacy analyses were by intention to treat and safety analyses were done in all patients who received any amount of study drug. This study is registered with ClinicalTrials.gov, number NCT01755767.

FINDINGS

Between Dec 27, 2012, and Dec 10, 2015, 340 patients were randomly assigned to receive tivantinib (n=226) or placebo (n=114). At a median follow-up of 18·1 months (IQR 14·1-23·1), median overall survival was 8·4 months (95% CI 6·8-10·0) in the tivantinib group and 9·1 months (7·3-10·4) in the placebo group (hazard ratio 0·97; 95% CI 0·75-1·25; p=0·81). Grade 3 or worse treatment-emergent adverse events occurred in 125 (56%) of 225 patients in the tivantinib group and in 63 (55%) of 114 patients in the placebo group, with the most common being ascites (16 [7%] patients]), anaemia (11 [5%] patients), abdominal pain (nine [4%] patients), and neutropenia (nine [4%] patients) in the tivantinib group. 50 (22%) of 226 patients in the tivantinib group and 18 (16%) of 114 patients in the placebo group died within 30 days of the last dose of study medication, and general deterioration (eight [4%] patients) and hepatic failure (four [2%] patients) were the most common causes of death in the tivantinib group. Three (1%) of 225 patients in the tivantinib group died from a treatment-related adverse event (one sepsis, one anaemia and acute renal failure, and one acute coronary syndrome).

INTERPRETATION

Tivantinib did not improve overall survival compared with placebo in patients with MET-high advanced hepatocellular carcinoma previously treated with sorafenib. Although this METIV-HCC trial was negative, the study shows the feasibility of doing integral tissue biomarker studies in patients with advanced hepatocellular carcinoma. Additional randomised studies are needed to establish whether MET inhibition could be a potential therapy for some subsets of patients with advanced hepatocellular carcinoma.

FUNDING

ArQule Inc and Daiichi Sankyo (Daiichi Sankyo Group).

Contrast agents in dynamic contrast-enhanced magnetic resonance imaging

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is a noninvasive method to assess angiogenesis, which is widely used in clinical applications including diagnosis, monitoring therapy response and prognosis estimation in cancer patients. Contrast agents play a crucial role in DCE-MRI and should be carefully selected in order to improve accuracy in DCE-MRI examination. Over the past decades, there was much progress in the development of optimal contrast agents in DCE-MRI. In this review, we describe the recent research advances in this field and discuss properties of contrast agents, as well as their advantages and disadvantages. Finally, we discuss the research perspectives for improving this promising imaging method.

Tumor and circulating biomarkers in patients with second-line hepatocellular carcinoma from the randomized phase II study with tivantinib

ARQ 197-215 was a randomized placebo-controlled phase II study testing the MET inhibitor tivantinib in second-line hepatocellular carcinoma (HCC) patients. It identified tumor MET as a key biomarker in HCC.Aim of this research was to study the prognostic and predictive value of tumor (MET, the receptor tyrosine kinase encoded by the homonymous MNNG-HOS transforming gene) and circulating (MET, hepatocyte growth factor [HGF], alpha-fetoprotein [AFP], vascular endothelial growth factor [VEGF]) biomarkers in second-line HCC. Tumor MET-High status was centrally assessed by immunohistochemistry. Circulating biomarkers were centrally analyzed on serum samples collected at baseline and every 4-8 weeks, using medians as cut-off to determine High/Low status. Tumor MET, tested in 77 patients, was more frequently High after (82%) versus before (40%) sorafenib. A significant interaction (p = 0.04) between tivantinib and baseline tumor MET in terms of survival was observed. Baseline circulating MET and HGF (102 patients) High status correlated with shorter survival (HR 0.61, p = 0.03, and HR 0.60, p = 0.02, respectively), while the association between AFP (104 patients) or VEGF (103 patients) status and survival was non-significant.

CONCLUSIONS

Tumor MET levels were higher in patients treated with sorafenib. Circulating biomarkers such as MET and HGF may be prognostic in second-line HCC. These results need to be confirmed in larger randomized clinical trials.

Molecular Pharmacodynamics-Guided Scheduling of Biologically Effective Doses: A Drug Development Paradigm Applied to MET Tyrosine Kinase Inhibitors

The development of molecularly targeted agents has benefited from use of pharmacodynamic markers to identify "biologically effective doses" (BED) below MTDs, yet this knowledge remains underutilized in selecting dosage regimens and in comparing the effectiveness of targeted agents within a class. We sought to establish preclinical proof-of-concept for such pharmacodynamics-based BED regimens and effectiveness comparisons using MET kinase small-molecule inhibitors. Utilizing pharmacodynamic biomarker measurements of MET signaling (tumor pY1234/1235MET/total MET ratio) in a phase 0-like preclinical setting, we developed optimal dosage regimens for several MET kinase inhibitors and compared their antitumor efficacy in a MET-amplified gastric cancer xenograft model (SNU-5). Reductions in tumor pY1234/1235MET/total MET of 95%-99% were achievable with tolerable doses of EMD1214063/MSC2156119J (tepotinib), XL184 (cabozantinib), and XL880/GSK1363089 (foretinib), but not ARQ197 (tivantinib), which did not alter the pharmacodynamic biomarker. Duration of kinase suppression and rate of kinase recovery were specific to each agent, emphasizing the importance of developing customized dosage regimens to achieve continuous suppression of the pharmacodynamic biomarker at the required level (here, ≥90% MET kinase suppression). The customized dosage regimen of each inhibitor yielded substantial and sustained tumor regression; the equivalent effectiveness of customized dosage regimens that achieve the same level of continuous molecular target control represents preclinical proof-of-concept and illustrates the importance of proper scheduling of targeted agent BEDs. Pharmacodynamics-guided biologically effective dosage regimens (PD-BEDR) potentially offer a superior alternative to pharmacokinetic guidance (e.g., drug concentrations in surrogate tissues) for developing and making head-to-head comparisons of targeted agents. Mol Cancer Ther; 17(3); 698-709. ©2018 AACR.

Circulating and disseminated tumor cells: diagnostic tools and therapeutic targets in motion

Enumeration of circulating tumor cells (CTCs) in peripheral blood with the gold standard CellSearchTM has proven prognostic value for tumor recurrence and progression of metastatic disease. Therefore, the further molecular characterization of isolated CTCs might have clinical relevance as liquid biopsy for therapeutic decision-making and to monitor disease progression. The direct analysis of systemic cancer appears particularly important in view of the known disparity in expression of therapeutic targets as well as epithelial-to-mesenchymal transition (EMT)-based heterogeneity between primary and systemic tumor cells, which all substantially complicate monitoring and therapeutic targeting at present. Since CTCs are the potential precursor cells of metastasis, their in-depth molecular profiling should also provide a useful resource for target discovery. The present review will discuss the use of systemically spread cancer cells as liquid biopsy and focus on potential target antigens.

Randomized phase 2 study of tivantinib plus erlotinib versus single-agent chemotherapy in previously treated KRAS mutant advanced non-small cell lung cancer

BACKGROUND

KRAS mutations are identified in approximately 25% of non-small cell lung cancer (NSCLC) cases and are associated with resistance to currently available targeted therapies. The MET oncogene may be implicated in malignant progression of KRAS-mutant tumors. In a pre-specified subset analysis of KRAS mutant cancers in an earlier phase 2 study of erlotinib plus the oral MET inhibitor tivantinib, combination therapy was associated with substantial clinical benefit compared to erlotinib alone (progression-free survival [PFS] HR 0.18; P < 0.01). The current study was conducted to evaluate this combination further in KRAS mutant non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

Previously treated patients with advanced KRAS mutant NSCLC were randomized to receive either oral tivantinib (360 mg twice daily) plus erlotinib (150 mg daily) (ET) or single-agent chemotherapy (investigator's choice of pemetrexed, docetaxel, or gemcitabine) (C). The primary endpoint was PFS. At progression, crossover from C to ET was permitted.

RESULTS

Ninety-six patients were randomly assigned to ET (n = 51) or to C (n = 45). Median PFS was 1.7 months (mos) for ET and 4.3 mos for C (HR 1.19; 95% CI, 0.71-1.97; P = 0.50). There was no difference in overall survival (HR 1.20; 95% CI, 0.76-1.88; P = 0.44). There were 4 partial responses in the C arm, and none in the ET arm. Overall, adverse events occurred more frequently in the C arm, with more cytopenias, nausea, fatigue, and alopecia. Dermatologic toxicities were more common in the ET arm.

CONCLUSION

In previously treated patients with advanced KRAS mutant NSCLC, the combination of the MET inhibitor tivantinib and erlotinib is not superior to conventional single-agent chemotherapy.

First-in-human phase I dose escalation study of MK-8033 in patients with advanced solid tumors

Background C-Met, which is frequently activated in multiple cancers, has been implicated in tumor formation, progression, metastasis, angiogenesis, and resistance to multiple therapies. MK-8033 is a small-molecule inhibitor of c-Met that binds preferentially to the activated conformation, and has demonstrated anti-tumor activity in preclinical models. This first-in-human trial was performed to establish the safety and maximum tolerated dose (MTD), as well as preliminary pharmacokinetics (PK) and clinical activity. Methods Forty-seven patients were enrolled in three parts. The primary objective of Parts A and B was safety, whereas Part C evaluated the effect of proton-pump inhibitors on MK-8033 absorption. Dose escalation used an accelerated continual reassessment method, and dose-limiting toxicities (DLTs) were any treatment-related, first course non-hematologic grade ≥ 3 toxicity (except alopecia or inadequately treated nausea/vomiting/diarrhea), grade 4 hematologic toxicity (except grade 3 neutropenic fever and thrombocytopenia), or toxicity where treatment is held >3 weeks. Results Forty-six patients were treated across nine dose levels, and the MTD was 750 mg twice daily. DLTs were fatigue, nausea, vomiting, transaminitis, and hypokalemia. Most frequent toxicities were fatigue (28.3%), nausea (21.7%), and alopecia (19.6%), predominately grade ≤ 2. One patient with endometriod adenocarcinoma achieved a partial response and eight had stable disease. Median progression-free survival (PFS) was 57 days. Strikingly, the PFS for the one responder was 846 days. PK results showed that proton-pump inhibitors have no effect on MK-8033 absorption. Conclusion MK-8033 was well tolerated with no significant toxicity issues, albeit with limited clinical activity. Unfortunately, the company decided to discontinue further clinical development of MK-8033.

Evaluation of the pharmacokinetic drug interaction potential of tivantinib (ARQ 197) using cocktail probes in patients with advanced solid tumours

AIMS

This phase 1, open-label, crossover study sought to evaluate drug-drug interactions between tivantinib and cytochrome P450 (CYP) substrates and tivantinib and P-glycoprotein.

METHODS

The effect of tivantinib doses on the pharmacokinetics of the probe drugs for CYP1A2 (caffeine), CYP2C9 (S-warfarin), CYP2C19 (omeprazole), and CYP3A4 (midazolam), and for P-glycoprotein (digoxin) was investigated in 28 patients with advanced cancer using a cocktail probe approach. Patients received single doses of probe drugs alone and, after 5 days of treatment, with tivantinib 360 mg twice daily.

RESULTS

The ratios of geometric least squares mean (90% confidence interval) for the area under the concentration-time curve from time zero to the last quantifiable concentration in the presence/absence of tivantinib were 0.97 (0.89-1.05) for caffeine, 0.88 (0.76-1.02) for S-warfarin, 0.89 (0.60-1.31) for omeprazole, 0.83 (0.67-1.02) for midazolam, and 0.69 (0.51-0.94) for digoxin. Similar effects were observed for maximum plasma concentrations; the ratio for digoxin in the presence/absence of tivantinib was 0.75 (0.60-0.95).

CONCLUSIONS

The data suggest that tivantinib 360 mg twice daily has either a minimal or no effect on the pharmacokinetics of probe drugs for CYP1A2, CYP2C9, CYP2C19 and CYP3A4 substrates, and decreases the systemic exposure of P-glycoprotein substrates when administered with tivantinib.

Correlation among genetic variations of c-MET in Chinese patients with non-small cell lung cancer

Background

The purpose of our research was to determine the correlation of amplification, protein expression and somatic mutation of c-MET in IIIb-IV stage NSCLC (Non-small cell lung cancer). We also explored correlation of c-MET variation with clinical outcome.

Results

c-MET expression was observed in 28.6% (56/196) cases, and among those 13.8% (27/196) were shown to be FISH positive. Only 2.67% patients in this study carried the c-MET mutation. Cases with c-MET FISH positive were all IHC positive ,but in IHC positive cases, only half were FISH positive. Among patients with IHC²⁺ staining, 35.5% was FISH positive, while cases with IHC³⁺ staining,64% was FISH positive. Both protein expression and copy number of c-MET did not significantly correlate with clinical prognosis in these patients treated with EGFR-TKIs.

Conclusions

IHC could be used as a preliminary screening method for c-MET copy number amplification and should be confirmed by FISH only in IHC positive case which facilitate selection of ALK or MET inhibitor therapy.

Methods

c-MET gene copy number, protein expression and somatic mutation for exon 14 were detected by fluorescent- In-Situ-Hybridization (FISH), Immunohistochemistry (IHC), and Denaturing-High-Performance-Liquid-Chromatography (DHPLC), respectively, in 196 NSCLC patients. The relationship between c-MET abnormalities and clinical outcome of targeted therapy was analyzed by McNemar's test.

The Prognostic Significance of c-MET and EGFR Overexpression in Resected Gastric Adenocarcinomas

OBJECTIVES

Epidermal growth factor receptor (EGFR) and c-MET are tyrosine kinase growth factor receptors implicated in gastric cancer (GC), and their pathways appear to be interdependent. The aim of this study was to investigate the prognostic value of EGFR and c-MET protein overexpression by immunohistochemistry in Canadian patients with resected GC and correlate it with clinicopathologic characteristics and overall survival (OS).

MATERIALS AND METHODS

Tissue microarray blocks were constructed from 120 resected GCs stained with EGFR and c-MET and scored semiquantitatively (0 to 3+). Each receptor's expression was compared with clinicopathologic characteristics and survival. Descriptive statistics, Kaplan-Meyer, and Cox regression were used for statistical analyses.

RESULTS

Of the 113 interpretable cases, overexpression of EGFR and c-MET was noted in 17 (15%) and 65 (57%), respectively; coexpression of EGFR and c-MET was observed in 12 (10%) of GC. EGFR and c-MET overexpression correlated with poor OS: median 13 versus 30 months in EGFR positive versus negative GC (hazard ratio [HR]=1.67, P=0.11); 27 versus 49 months in c-MET positive versus negative GC (HR=1.17, P=0.49), respectively. GC coexpressing EGFR and c-MET was significantly correlated with poor survival: 12 versus 29 months in double-positive versus rest of tumors both in univariate (HR=2.62, P=0.003) and multivariate analyses (HR=2.58, P=0.01).

CONCLUSIONS

This study describes the prevalence and prognostic value of EGFR and c-MET in a Canadian population of patients undergoing curative intent resection for GC. Both c-MET and EGFR overexpression trended toward poor OS, but only the group with EGFR+/c-MET+ GC reached statistical significance on multivariate analysis.

A phase 1 study of the c-Met inhibitor, tivantinib (ARQ197) in children with relapsed or refractory solid tumors: A Children's Oncology Group study phase 1 and pilot consortium trial (ADVL1111)

BACKGROUND

The c-Met receptor tyrosine kinase is dysregulated in many pediatric cancers. Tivantinib is an oral small molecule that inhibits the c-Met receptor tyrosine kinase. A phase 1 and pharmacokinetic (PK) trial evaluating tivantinib was conducted in children with relapsed/refractory solid tumors.

METHODS

Oral tivantinib capsules were administered twice daily with food, continuously in 28-day cycles. Dose levels 170, 200, and 240 mg/m² /dose were evaluated using a rolling-six design (Part A). In Part B, subjects received tivantinib powder sprinkled on food at the recommended phase 2 dose (RP2D) from Part A. PK, CYP2C19 genotyping, and baseline tumor tissue c-Met expression were analyzed.

RESULTS

Thirty-six patients were enrolled: 20 in Part A, 6 in a PK expansion cohort, and 10 in Part B. Fifteen patients had primary central nervous system tumors and 21 had solid tumors. In Part A, there were no dose-limiting toxicities. One grade 4 intracranial hemorrhage occurred in a patient with a progressive brain tumor in the expanded PK cohort (240 mg/m² ). PK analysis showed marked interpatient variability (20-fold) in the C_max and AUC_0-8h across all dose levels. Sprinkling tivantinib powder over food did not alter exposure. Membranous and total c-Met expression was moderate (2), low (4), or not detected (26). Two patients had stable disease as the best response.

CONCLUSIONS

The RP2D of tivantinib given with food in children with refractory solid tumors is 240 mg/m² /dose. PK of tivantinib in children demonstrated high variability. Objective responses were not observed in this phase 1 trial.

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.

Modulating Protein-Protein Interactions of the Mitotic Polo-like Kinases to Target Mutant KRAS

Mutations activating KRAS underlie many forms of cancer, but are refractory to therapeutic targeting. Here, we develop Poloppin, an inhibitor of protein-protein interactions via the Polo-box domain (PBD) of the mitotic Polo-like kinases (PLKs), in monotherapeutic and combination strategies to target mutant KRAS. Poloppin engages its targets in biochemical and cellular assays, triggering mitotic arrest with defective chromosome congression. Poloppin kills cells expressing mutant KRAS, selectively enhancing death in mitosis. PLK1 or PLK4 depletion recapitulates these cellular effects, as does PBD overexpression, corroborating Poloppin's mechanism of action. An optimized analog with favorable pharmacokinetics, Poloppin-II, is effective against KRAS-expressing cancer xenografts. Poloppin resistance develops less readily than to an ATP-competitive PLK1 inhibitor; moreover, cross-sensitivity persists. Poloppin sensitizes mutant KRAS-expressing cells to clinical inhibitors of c-MET, opening opportunities for combination therapy. Our findings exemplify the utility of small molecules modulating the protein-protein interactions of PLKs to therapeutically target mutant KRAS-expressing cancers.

Extracranial Soft-Tissue Tumors: Repeatability of Apparent Diffusion Coefficient Estimates from Diffusion-weighted MR Imaging

Purpose To assess the repeatability of apparent diffusion coefficient (ADC) estimates in extracranial soft-tissue diffusion-weighted magnetic resonance imaging across a wide range of imaging protocols and patient populations. Materials and Methods Nine prospective patient studies and one prospective volunteer study, performed between 2006 and 2016 with research ethics committee approval and written informed consent from each subject, were included in this single-institution study. A total of 141 tumors and healthy organs were imaged twice (interval between repeated examinations, 45 minutes to 10 days, depending the on study) to assess the repeatability of median and mean ADC estimates. The Levene test was used to determine whether ADC repeatability differed between studies. The Pearson linear correlation coefficient was used to assess correlation between coefficient of variation (CoV) and the year the study started, study size, and volumes of tumors and healthy organs. The repeatability of ADC estimates from small, medium, and large tumors and healthy organs was assessed irrespective of study, and the Levene test was used to determine whether ADC repeatability differed between these groups. Results CoV aggregated across all studies was 4.1% (range for each study, 1.7%-6.5%). No correlation was observed between CoV and the year the study started or study size. CoV was weakly correlated with volume (r = -0.5, P = .1). Repeatability was significantly different between small, medium, and large tumors (P < .05), with the lowest CoV (2.6%) for large tumors. There was a significant difference in repeatability between studies-a difference that did not persist after the study with the largest tumors was excluded. Conclusion ADC is a robust imaging metric with excellent repeatability in extracranial soft tissues across a wide range of tumor sites, sizes, patient populations, and imaging protocol variations. Online supplemental material is available for this article.

Autophagy is required for crizotinib-induced apoptosis in MET-amplified gastric cancer cells

MET amplification has been clinically credentialed as a therapeutic target in gastric cancer, but the molecular mechanisms underlying sensitivity and resistance to MET inhibitors are still not well understood. Using whole-genome mRNA expression profiling, we identified autophagy as a top molecular pathway that was activated by the MET inhibitor crizotinib in drug-sensitive human gastric cancer cells, and functional studies confirmed that crizotinib increased autophagy levels in the drug-sensitive cells in a concentration-dependent manner. We then used chemical and molecular approaches to inhibit autophagy in order to define its role in cell death. The clinically available inhibitor of autophagy, chloroquine, or RNAi-mediated knockdown of two obligate components of the autophagy pathway (ATG5 and ATG7) blocked cell death induced by crizotinib or RNAi-mediated knockdown of MET, and mechanistic studies localized the effects of autophagy to cytochrome c release from the mitochondria. Overall, the data reveal a novel relationship between autophagy and apoptosis in gastric cancer cells exposed to MET inhibitors. The observations suggest that autophagy inhibitors should not be used to enhance the effects of MET inhibitors in gastric cancer patients.

A phase I study of tivantinib in combination with temsirolimus in patients with advanced solid tumors

Background A wide variety of human cancers exhibit dysregulated c-Met activity that has implications in oncogenesis. Phosphorylation of c-Met results in activation of the PI3K/AKT/mTOR pathway. Combined blockade of c-Met and mTOR pathways has shown efficacy in preclinical studies. Tivantinib is a c-Met inhibitor and temsirolimus is a selective mTOR inhibitor. We aimed to determine the maximum tolerated dose (MTD) and the recommended phase II dose (RP2D), dose-limiting toxicities (DLT), adverse events (AEs), clinical activity and pharmacokinetic (PK) parameters of the combination. Methods This open-label phase I study used a 3 + 3 dose escalation design. Patients (pts) were treated with escalating doses of tivantinib (120-360 mg tablets orally twice daily) and temsirolimus (20 mg IV weekly) followed by dose expansion at the MTD. Separate cohorts were planned for extensive (normal) and poor tivantinib metabolizers based on CYP2C19 genotypes. Cycles were 28 days besides cycle 1 that was 35 days to allow for PK analysis. Results Twenty-nine pts. [median age 58 (range 28-77)] were enrolled (21 in dose escalation and 8 in dose expansion). All were extensive CYP2C19 metabolizers. The most common types of cancer were colorectal, ovarian and non-small cell lung. Sixteen out of 21 and 6 out of 8 pts. were evaluable for DLT evaluation per protocol in the dose escalation and dose expansion phases, respectively. Pts remained on study for a median of 71 days (range 18-296). The MTD and RP2D was tivantinib 240 mg twice daily and temsirolimus 20 mg weekly. DLTs included grade (gr) 4 neutropenia (2 pts.; 1 with gr 3 febrile neutropenia), gr 3 abdominal pain (1 pt) and gr 2 mucositis resulting in inadequate drug delivery. The most common treatment related AEs grade ≥ 2 included: anemia (gr 2 in 9 pts., gr 3 in 3 pts), fatigue (gr 2 in 10 pts), anorexia (gr 2 in 9 pts), hypoalbuminemia (gr 2 in 6 pts., gr 3 in 2 pts), hypophosphatemia (gr 2 in 2 pts., gr 3 in 5 pts) and nausea (gr 2 in 6 pts., gr 3 in 1 pt). One pt. with ovarian cancer had a confirmed partial response and remained on study for 10 months, a second patient with ovarian cancer had stable disease and remained on study for 6 months and a third pt. with squamous cell carcinoma of the tongue had stable disease and remained on study for 7 months. Pharmacokinetic analysis showed that there is no interaction in the plasma concentrations between tivantinib and temsirolimus. Conclusions The combination of tivantinib with temsirolimus appears to be well tolerated with evidence of clinical activity.

The Therapeutic Potential of Targeting the HGF/cMET Axis in Ovarian Cancer

Survival rates for ovarian cancer have remained relatively stable for the past 2 decades despite advances in surgical techniques and cytotoxic chemotherapeutics, indicating a requirement for better therapies. One pathway currently proposed for targeting is the HGF/cMET pathway. Upregulated in a number of tumour types, cMET is a tyrosine kinase receptor expressed on epithelial cells. In ovarian cancer, it has been identified as highly expressed in the four major subtypes, with expression estimates ranging from 11 to 68 % of cases. HGF, the only known ligand for cMET, is found at high levels in both serum and ascites in women with ovarian cancer, and is proposed to induce both migration and metastasis. However, clinically validated biomarkers are not yet available for either HGF or cMET, preventing a clear understanding of the true rate of overexpression, or its correlation with prognosis. Despite this, a number of agents against HGF and cMET are currently being investigated in clinical trials for multiple tumour types, including ovarian. However, a lack of patient selection, biomarker usage, and post hoc analysis correlating response with expression has resulted in the majority of these trials showing little beneficial effect from these agents, indicating that additional research is required to determine their usefulness in patients with ovarian cancer.

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.

Phase II study of the c-MET inhibitor tivantinib (ARQ 197) in patients with relapsed or relapsed/refractory multiple myeloma

The hepatocyte growth factor/c-MET pathway has been implicated in the pathobiology of multiple myeloma, and c-MET inhibitors induce myeloma cell apoptosis, suggesting that they could be useful clinically. We conducted a phase II study with the c-MET inhibitor tivantinib in patients with relapsed, or relapsed and refractory myeloma whose disease had progressed after one to four prior therapies. Tivantinib, 360 mg orally per dose, was administered twice daily continuously over a 4-week treatment cycle without a cap on the number of allowed cycles, barring undue toxicities or disease progression. Primary objectives were to determine the overall response rate and the toxicities of tivantinib in this patient population. Sixteen patients were enrolled in a two-stage design. Notable grade 3 and 4 hematological adverse events were limited to neutropenia in five and four patients, respectively. Nonhematological adverse events of grade 3 or higher included hypertension (in four patients); syncope, infection, and pain (two each); and fatigue, cough, and pulmonary embolism (one each). Four of 11 evaluable patients (36%) had stable disease as their best response, while the remainder showed disease progression. Overall, tivantinib as a single agent did not show promise for unselected relapsed/refractory myeloma patients. However, the ability to achieve stable disease does suggest that combination regimens incorporating targeted inhibitors in patients with c-MET pathway activation could be of interest.

Profile of tivantinib and its potential in the treatment of hepatocellular carcinoma: the evidence to date

Hepatocellular carcinoma (HCC) is the fastest rising cause of cancer-related death in the United States and carries a very poor prognosis, with a median survival time of <50% at 1 year for advanced disease. To date, sorafenib is the only therapy approved by the Food and Drug Administration for the treatment of advanced HCC. Tivantinib (ARQ-197), a non-ATP competitive inhibitor of cellular mesenchymal–epithelial transcription factor (c-MET), has shown a survival benefit in patients with advanced HCC who have failed or are intolerant to sorafenib in Phase I and II trials. Those patients who have tumors with high concentrations of MET (MET-high) appear to derive the greatest benefit from tivantinib therapy. Currently, two large randomized double-blind placebo-controlled Phase III trials (METIV-HCC [NCT01755767] and JET-HCC [NCT02029157]) are evaluating tivantinib in patients with MET-high advanced HCC, with the primary end points of overall survival and progression-free survival, respectively. This study reviews the evidence for the use of tivantinib in advanced HCC. Specific topics addressed include the pharmacology, dosing, toxicity, and biomarkers associated with tivantinib use.

Clinical Significance of C-MET Overexpression and Epidermal Growth Factor Receptor Mutation in Platinum-Based Adjuvant Chemotherapy Outcome in Surgically Resected Lung Adenocarcinoma

PURPOSE

We retrospectively assessed the role of C-MET expression and epidermal growth factor receptor (EGFR) mutation on survival following platinum-based adjuvant chemotherapy. The impact of C-MET on survival was also investigated in relation to EGFR mutation status.

METHODS

We enrolled 311 patients with resected lung adenocarcinoma (high-risk stage 1B-3A), and performed immunohistochemistry (IHC) using C-MET- and mutant EGFR (EGFRmut)-specific antibodies in tissue microarrays.

RESULTS

Adjuvant chemotherapy was administered to 151 patients, 96 of whom relapsed and 85 died by the end of the study. On IHC, C-MET and EGFRmut were positive in 141 (45.3 %) and 88 (28.3 %) cases, respectively. On univariate analysis, adjuvant chemotherapy prolonged relapse-free survival (RFS) and overall survival (OS) in C-MET(+) patients (RFS p = 0.035; OS p = 0.013) but not in C-MET(-) patients. On multivariate analysis, adjuvant chemotherapy was a positive independent prognostic factor in C-MET(+) (RFS p = 0.013; OS p = 0.006) but not in C-MET(-) patients. In addition, univariate analysis showed no effect of EGFRmut status on RFS and OS after chemotherapy, whereas multivariate analysis revealed that adjuvant chemotherapy increased RFS in both EGFRmut(+) and EGFRmut(-) patients [EGFRmut(+) p = 0.033; EGFRmut(-) p = 0.030]. C-MET was a negative prognostic factor for RFS (p = 0.045) and OS (p = 0.007) in the EGFRmut(-) group but not in the EGFRmut(+) group, on multivariate analysis.

CONCLUSIONS

Our data indicate that patients with C-MET overexpression should be considered for adjuvant chemotherapy, and that C-MET negatively correlates with survival in patients with wild-type, but not mutant, EGFR.

Therapy Monitoring with Functional and Molecular MR Imaging

Cancer therapy is mainly based on different combinations of surgery, radiotherapy, and chemotherapy. Additionally, targeted therapies (designed to disrupt specific tumor hallmarks, such as angiogenesis, metabolism, proliferation, invasiveness, and immune evasion), hormonotherapy, immunotherapy, and interventional techniques have emerged as alternative oncologic treatments. Conventional imaging techniques and current response criteria do not always provide the necessary information regarding therapy success particularly to targeted therapies. In this setting, MR imaging offers an attractive combination of anatomic, physiologic, and molecular information, which may surpass these limitations, and is being increasingly used for therapy response assessment.

uPAR enhances malignant potential of triple-negative breast cancer by directly interacting with uPA and IGF1R

BACKGROUND

Due to lack of a targeted therapy for the triple-negative breast cancer (TNBC) patients, it is important to explore this aggressive breast cancer type in more detail and to establish novel therapeutic approaches. TNBC is defined negative for the protein expression of oestrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2). One prominent feature of this cancer type is the frequent overexpression of major components of the urokinase-type plasminogen activator system (uPAS) including uPA, its receptor uPAR and the inhibitor PAI-1, which may be valuable as therapeutic targets.

METHODS

Direct interactions of uPAR with interactors were demonstrated by immunoprecipitations and proximity ligation assays. For stable knockdowns of target proteins, lentiviral vectors were used and the effects were analysed by immunoblottings and using in vitro cell viability, migration and invasion assays. Immunohistochemical and statistical analyses of biomarkers and clinical parameters were conducted in a TNBC cohort (n = 174).

RESULTS

Direct tumour-promoting interactions of uPAR with uPA and the insulin-like growth factor receptor 1 (IGF1R) were shown in TNBC cells and these interactions were significantly reduced (p = 0.001) when uPAR was downregulated. The combined knockdown of uPAR and uPA or IGF1R additively and significantly reduced cell viability, migration and invasion of the model cell lines. In TNBC tissue, the complexes formed by uPAR with uPA or with IGF1R significantly correlated with the histological grade (p = 0.0019) as well as with cathepsin B and D (p ≤ 0.0001) that are implicated in cell invasion and metastasis.

CONCLUSIONS

Our outcomes show that not only overexpressed biomarkers promote tumourigenesis, but rather their interactions further potentiate tumour progression. This study emphasises the potential of combined approaches targeting uPAR and its interactors with regard to an improved therapy of TNBC.

Pharmacodynamic Response of the MET/HGF Receptor to Small-Molecule Tyrosine Kinase Inhibitors Examined with Validated, Fit-for-Clinic Immunoassays

PURPOSE

Rational development of targeted MET inhibitors for cancer treatment requires a quantitative understanding of target pharmacodynamics, including molecular target engagement, mechanism of action, and duration of effect.

EXPERIMENTAL DESIGN

Sandwich immunoassays and specimen handling procedures were developed and validated for quantifying full-length MET and its key phosphospecies (pMET) in core tumor biopsies. MET was captured using an antibody to the extracellular domain and then probed using antibodies to its C-terminus (full-length) and epitopes containing pY1234/1235, pY1235, and pY1356. Using pMET:MET ratios as assay endpoints, MET inhibitor pharmacodynamics were characterized in MET-amplified and -compensated (VEGFR blockade) models.

RESULTS

By limiting cold ischemia time to less than two minutes, the pharmacodynamic effects of the MET inhibitors PHA665752 and PF02341066 (crizotinib) were quantifiable using core needle biopsies of human gastric carcinoma xenografts (GTL-16 and SNU5). One dose decreased pY1234/1235 MET:MET, pY1235-MET:MET, and pY1356-MET:MET ratios by 60% to 80% within 4 hours, but this effect was not fully sustained despite continued daily dosing. VEGFR blockade by pazopanib increased pY1235-MET:MET and pY1356-MET:MET ratios, which was reversed by tivantinib. Full-length MET was quantifiable in 5 of 5 core needle samples obtained from a resected hereditary papillary renal carcinoma, but the levels of pMET species were near the assay lower limit of quantitation.

CONCLUSIONS

These validated immunoassays for pharmacodynamic biomarkers of MET signaling are suitable for studying MET responses in amplified cancers as well as compensatory responses to VEGFR blockade. Incorporating pharmacodynamic biomarker studies into clinical trials of MET inhibitors could provide critical proof of mechanism and proof of concept for the field. Clin Cancer Res; 22(14); 3683-94. ©2016 AACR.