Targeted MET Inhibition in Castration-Resistant Prostate Cancer: A Randomized Phase 2 Study and Biomarker Analysis With Rilotumumab Plus Mitoxantrone and Prednisone.
ABSTRACT PURPOSE: To evaluate the efficacy, safety, biomarkers, and pharmacokinetics of rilotumumab, a fully human, monoclonal antibody against hepatocyte growth factor (HGF)/scatter factor, combined with mitoxantrone and prednisone (MP) in patients with castration-resistant prostate cancer (CRPC). EXPERIMENTAL DESIGN: This double-blinded phase 2 study randomized (1:1:1) patients with progressive, taxane-refractory CRPC to receive MP (12 mg/m2 IV day 1, 5 mg BID orally days 1-21, respectively) plus rilotumumab 15 mg/kg, rilotumumab 7.5 mg/kg, or placebo (IV day 1) every 3 weeks. The primary endpoint was overall survival (OS). RESULTS: 142 patients were randomized. Median OS was 12.2 versus 11.1 months (HR, 1.10; 80% CI, 0.82-1.48) in the combined rilotumumab versus control arms. Median progression-free survival was 3.0 versus 2.9 months (HR, 1.02; 80% CI, 0.79-1.31). Treatment appeared well tolerated with peripheral edema (24% versus 8%) being more common with rilotumumab. A trend toward unfavorable OS was observed in patients with high tumor MET expression regardless of treatment. Soluble MET levels increased in all treatment arms. Total HGF levels increased in the rilotumumab arms. Rilotumumab showed linear pharmacokinetics when co-administered with MP. CONCLUSIONS: Rilotumumab plus MP had manageable toxicities and showed no efficacy improvements in this estimation study. High tumor MET expression may identify CRPC patients with poorer prognosis.
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ABSTRACT: The MET/hepatocyte growth-factor (HGF) signaling pathway plays a key role in the processes of embryogenesis, wound healing, and organ regeneration. Aberrant activation of MET/HGF occurs through multiple mechanisms including gene amplification, mutation, protein overexpression, and abnormal gene splicing interrupting autocrine and paracrine regulatory feedback mechanisms. In many cancers including non-small-cell lung cancer, colorectal, gastric, renal, and hepatocellular cancer, dysregulation of MET may lead to a more aggressive cancer phenotype and may be a negative prognostic indicator. Successful therapeutic targeting of the MET/HGF pathway has been achieved using monoclonal antibodies against the MET receptor and its ligand HGF in addition to MET-specific and multitargeted small-molecule tyrosine-kinase inhibitors with several drugs in late-phase clinical trials including onartuzumab, rilotumumab, tivantinib, and cabozantinib. MET frequently interacts with other key oncogenic tyrosine kinases including epidermal growth-factor receptor (EGFR) and HER-3 and these interactions may be responsible for resistance to anti-EGFR therapies. Similarly, resistance to MET inhibition may be mediated through EGFR activation, or alternatively by increasing levels of MET amplification or acquisition of novel "gatekeeper" mutations. In order to optimize development of effective inhibitors of the MET/HGF pathway clinical trials must be enriched for patients with demonstrable MET-pathway dysregulation for which robustly standardized and validated assays are required.OncoTargets and Therapy 01/2014; 7:1001-14. · 1.34 Impact Factor
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ABSTRACT: MET is located on chromosome 7q31 and is a proto-oncogene that encodes for hepatocyte growth factor (HGF) receptor, a member of the receptor tyrosine kinase (RTK) family. HGF, also known as scatter factor (SF), is the only known ligand for MET. MET is a master regulator of cell growth and division (mitogenesis), mobility (motogenesis), and differentiation (morphogenesis); it plays an important role in normal development and tissue regeneration. The HGF-MET axis is frequently dysregulated in cancer by MET gene amplification, translocation, and mutation, or by MET or HGF protein overexpression. MET dysregulation is associated with an increased propensity for metastatic disease and poor overall prognosis across multiple tumor types. Targeting the dysregulated HGF-MET pathway is an area of active research; a number of monoclonal antibodies to HGF and MET, as well as small molecule inhibitors of MET, are under development. This review summarizes the key biological features of the HGF-MET axis, its dysregulation in cancer, and the therapeutic agents targeting the HGF-MET axis, which are in development.OncoTargets and Therapy 01/2014; 7:969-83. · 1.34 Impact Factor
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ABSTRACT: We previously found that prostate cancer stem-like cells (CSCs)/cancer-initiating cells (CICs) express hepatocyte growth factor (HGF) and that the HGF/c-MET proto-oncogene product (c-MET) signal has a role in the maintenance of prostate CSCs/CICs in an autocrine fashion. HGF is, thus, a novel marker for prostate CSCs/CICs. We hypothesized that high expression of HGF might be related to early recurrence of prostate cancer after radical prostatectomy, and the purpose of the present study was to evaluate the relationship between expression of HGF in prostate tissues and biochemical recurrence after radical prostatectomy. One hundred-one patients with prostate cancer who underwent open or laparoscopic radical prostatectomy from November 2008 to October 2011 with an adequate prostate-specific antigen (PSA) follow-up period, were investigated. Immunohistochemical staining of HGF was compared to biochemical recurrence after radical prostatectomy. Patients with tumors exhibiting HGF positivity of 5% or more had a significantly shorter biochemical recurrence-free period than that of patients whose tumor HGF positivity was less than 5% (p=0.001). In multivariate Cox regression, preoperative PSA and HGF positivity were independent predictors of biochemical recurrence following prostatectomy. Our finding suggests a direct link between expression of HGF, a novel prostate marker of CSCs/CICs, and biochemical recurrence after radical prostatectomy in patients with prostate cancer. Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.Anticancer research 01/2015; 35(1):413-8. · 1.87 Impact Factor