Selection criteria for c-Met-targeted therapies: emerging evidence for biomarkers

Phase I Dose-Escalation and -Expansion Study of Telisotuzumab (ABT-700), an Anti-c-Met Antibody, in Patients with Advanced Solid Tumors

This first-in-human phase I study evaluated the pharmacokinetics, safety, and preliminary efficacy of telisotuzumab, formerly called ABT-700, an antagonistic antibody directed against c-Met. For dose escalation (3+3 design), 3 to 6 patients with advanced solid tumors were enrolled into four dose cohorts (5-25 mg/kg). In the dose-expansion phase, a subset of patients was prospectively selected for MET amplification (FISH screening). Patients received telisotuzumab intravenously on day 1 every 21 days. For dose expansion, 15 mg/kg was chosen as the dose on the basis of safety, pharmacokinetics, and other data from the escalation cohorts. Forty-five patients were enrolled and received at least one dose of telisotuzumab (dose escalation, n = 15; dose expansion, n = 30). Telisotuzumab showed a linear pharmacokinetics profile; peak plasma concentration was proportional to dose level. There were no acute infusion reactions and no dose-limiting toxicities were observed. The most common treatment-related adverse events included hypoalbuminemia (n = 9, 20.0%) and fatigue (n = 5, 11.1%). By Response Evaluation Criteria In Solid Tumors (RECIST), 4 of 10 (40.0%) patients with MET-amplified tumors had confirmed partial response in target lesions (one ovarian, two gastric, and one esophageal), two (20.0%) had stable disease, three (30.0%) had progressive disease; one patient was unable to be evaluated. Among patients with nonamplified tumors (n = 35), no objective responses were observed; however, 11 patients had stable disease per RECIST criteria. In conclusion, telisotuzumab has an acceptable safety profile with clinical activity observed in patients with MET-amplified advanced solid tumors.

Reduced membranous MET expression is linked to bladder cancer progression

The MET protein is involved in the malignant progression of different tumors. This study aimed to analyze the relationship of MET expression with tumor phenotype and clinical outcome in bladder cancer and the role of gene amplification for MET overexpression. A bladder cancer tissue microarray containing 686 bladder cancers was analyzed by immunohistochemistry and by fluorescence in situ hybridization. MET immunostaining was seen in normal urothelium and was recorded in 459 of 560 analyzable urothelial carcinomas (82.0%). Low MET staining was associated with a more unfavorable tumor phenotype. MET staining was seen in 89.8% of 266 pTa, 81.1% of 132 pT1, and 69.4% of 160 pT2-4 cancers (P < 0.0001). MET staining was detectable in 92.4% of 66 grade 1, 85.6% of 257 grade 2, and 75.1% of 237 grade 3 cancers (P = 0.001). MET expression status was not associated with overall or tumor-specific survival in muscle-invasive cancers (pT2-4), tumor progression in pT1 cancers, or recurrences in pTa tumors. Only four of the analyzed tumors (0.8%) showed amplification of the MET gene. We conclude that MET is not overexpressed in urothelial cancer but rather downregulated in a fraction of cancers. Accordingly, rare amplification of the genomic area including the MET gene was not associated with MET protein overexpression.

The Met receptor tyrosine kinase: a key player in oncogenesis and drug resistance

The Met receptor tyrosine kinase (RTK) is an attractive oncology therapeutic target. Met and its ligand, HGF, play a central role in signaling pathways that are exploited during the oncogenic process, including regulation of cell proliferation, invasion, angiogenesis, and cancer stem cell regulation. Elevated Met and HGF as well as numerous Met genetic alterations have been reported in human cancers and correlate with poor outcome. Alterations of pathways that regulate Met, such as the ubiquitin ligase c-Cbl are also likely to activate Met in the oncogenic setting. Moreover, interactive crosstalk between Met and other receptors such as EGFR, HER2 and VEGFR, underlies a key role for Met in resistance to other RTK-targeted therapies. A large body of preclinical and clinical data exists that supports the use of either antibodies or small molecule inhibitors that target Met or HGF as oncology therapeutics. The prognostic potential of Met expression has been suggested from studies in numerous cancers including lung, renal, liver, head and neck, stomach, and breast. Clinical trials using Met inhibitors indicate that the level of Met expression is a determinant of trial outcome, a finding that is actively under investigation in multiple clinical scenarios. Research in Met prognostics and predictors of drug response is now shifting toward more sophisticated methodologies suitable for development as validated and effective biomarkers that can be partnered with therapeutics to improve patient survival.

EMD 1214063 and EMD 1204831 constitute a new class of potent and highly selective c-Met inhibitors

PURPOSE

The mesenchymal-epithelial transition factor (c-Met) receptor, also known as hepatocyte growth factor receptor (HGFR), controls morphogenesis, a process that is physiologically required for embryonic development and tissue repair. Aberrant c-Met activation is associated with a variety of human malignancies including cancers of the lung, kidney, stomach, liver, and brain. In this study, we investigated the properties of two novel compounds developed to selectively inhibit the c-Met receptor in antitumor therapeutic interventions.

EXPERIMENTAL DESIGN

The pharmacologic properties, c-Met inhibitory activity, and antitumor effects of EMD 1214063 and EMD 1204831 were investigated in vitro and in vivo, using human cancer cell lines and mouse xenograft models.

RESULTS

EMD 1214063 and EMD 1204831 selectively suppressed the c-Met receptor tyrosine kinase activity. Their inhibitory activity was potent [inhibitory 50% concentration (IC50), 3 nmol/L and 9 nmol/L, respectively] and highly selective, when compared with their effect on a panel of 242 human kinases. Both EMD 1214063 and EMD 1204831 inhibited c-Met phosphorylation and downstream signaling in a dose-dependent fashion, but differed in the duration of their inhibitory activity. In murine xenograft models, both compounds induced regression of human tumors, regardless of whether c-Met activation was HGF dependent or independent. Both drugs were well tolerated and induced no substantial weight loss after more than 3 weeks of treatment.

CONCLUSIONS

Our results indicate selective c-Met inhibition by EMD 1214063 and EMD 1204831 and strongly support clinical testing of these compounds in the context of molecularly targeted anticancer strategies.