Optical Imaging of Mesenchymal Epithelial Transition Factor (MET) for Enhanced Detection and Characterization of Primary and Metastatic Hepatic Tumors

Synthesis and Evaluation of a Novel c-Met-Targeting Cyclic Peptide as a Potential Diagnostic Agent for Colorectal Cancer

The mesenchymal-epithelial transition factor (c-Met) is a receptor tyrosine kinase linked to the proliferation, survival, invasion, and metastasis of several types of cancers, including colorectal cancer (CRC), particularly when aberrantly activated. Our study strategically designs peptides derived from interactions between c-Met and the antibody Onartuzumab. By utilizing a cyclic strategy, we achieved significantly enhanced peptide stability and affinity. Our in vitro assessments confirmed that the cyclic peptide HYNIC-cycOn exhibited a higher affinity (KD = 83.5 nM) and greater specificity compared with its linear counterpart. Through in vivo experiments, [99mTc]Tc-HYNIC-cycOn displayed exceptional tumor-targeting capabilities and minimal absorption in nontumor cells, as confirmed by single-photon emission computed tomography. Notably, the ratios of tumor to muscle and tumor to intestine, 1 h postinjection, were 4.78 ± 0.86 and 3.24 ± 0.47, respectively. Comparable ratios were observed in orthotopic CRC models, recording 4.94 ± 0.32 and 3.88 ± 0.41, respectively. In summary, [99mTc]Tc-HYNIC-cycOn shows substantial promise as a candidate for clinical applications. We show that [99mTc]Tc-HYNIC-cycOn can effectively target and visualize c-Met-expressing tumors in vivo, providing a promising approach for enhancing diagnostic accuracy when detecting c-Met in CRC.

FGF19-Based Mini Probe Targeting FGFR4 for Diagnosis and Surgical Navigation of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a frequent malignancy that has a high death rate and a high rate of recurrence following surgery, owing to insufficient surgical resection. Furthermore, HCC is prone to peritoneal metastasis (HCC-PM), resulting in a significant number of tiny cancer lesions, making surgical removal more challenging. As a potential imaging target, FGFR4 is highly expressed in tumors, especially in HCC, but is less expressed in the normal liver. In this study, we used computational simulation approaches to develop peptide I0 derived from FGF19, a particular ligand of FGFR4, and labeled it with the NIRF dye, MPA, for HCC detection. In surgical navigation, the TBR was 9.31 ± 1.36 and 8.57 ± 1.15 in HepG2 in situ tumor and HCC-PM models, respectively, indicating considerable tumor uptake. As a result, peptide I0 is an excellent clinical diagnostic reagent for HCC, as well as a tool for surgically resecting HCC peritoneal metastases.

Hyperpolarized [1-13C]Pyruvate Magnetic Resonance Spectroscopic Imaging for Evaluation of Early Response to Tyrosine Kinase Inhibition Therapy in Gastric Cancer

PURPOSE

To evaluate the use of hyperpolarized [1-13C]pyruvate magnetic resonance spectroscopic imaging (HP-13C MRSI) for quantitative measurement of early changes in glycolytic metabolism and its ability to predict response to pan-tyrosine kinase inhibitor (Pan-TKI) therapy in gastric cancer (GCa).

PROCEDURES

Pan-TKI afatinib-sensitive NCI-N87 and resistant SNU16 human GCa cells were assessed for GLUT1, hexokinase-II (HKII), lactate dehydrogenase (LDHA), phosphorylated AKT (pAKT), and phosphorylated MAPK (pMAPK) at 0-72 h of treatment with 0.1 μM afatinib. Subcutaneous NCI-N87 tumor-bearing nude mice underwent [18F]FDG PET/MRI and HP-13C MRSI at baseline and 4 days after treatment with afatinib 10 mg/kg/day or vehicle (n = 10/group). Changes in PET and HP-13C MRSI metabolic parameters were compared between the two groups. Imaging findings were correlated with tumor growth and histopathology over 3 weeks of treatment.

RESULTS

In vitro analysis showed a continuous decrease in LDHA, pAKT, and pMAPK in NCI-N87 compared to SNU16 cells within 72 h of treatment with afatinib, without a significant change in GLUT1 and HKII in either cell type. [18F]FDG PET of NCI-N87 tumors showed no significant change in PET measures at baseline and day 4 of treatment in either treatment group (SUVmean day 4/day 0: 2.7 ± 0.42/2.34 ± 0.38, p = 0.57 in the treated group vs. 1.73 ± 0.66/2.24 ± 0.43, p = 0.4 in the control group). HP-13C MRSI demonstrated significantly decreased lactate-to-pyruvate ratio (L/P) in treated tumors (L/P day 4/day 0: 0.83 ± 0.30/1.10 ± 0.20, p = 0.012 vs. 0.94 ± 0.20/0.98 ± 0.30, p = 0.75, in the treated vs. control group, respectively). Response to afatinib was confirmed with decreased tumor size over 3 weeks (11.10 ± 16.50 vs. 293.00 ± 79.30 mm3, p < 0.001, treated group vs. control group, respectively) and histopathologic evaluation.

CONCLUSIONS

HP-13C MRSI is a more representative biomarker of early metabolic changes in response to pan-TKI in GCa than [18F]FDG PET and could be used for early prediction of response to targeted therapies.

Mesenchymal-epithelial transition factor (MET) immunoreactivity in positive sentinel nodes from patients with melanoma

OBJECTIVE

Patients with cutaneous melanoma and a positive sentinel node (SN) are currently eligible for adjuvant treatment with targeted therapy and immune checkpoint inhibitors. Near-infrared (NIR) fluorescence imaging could be an alternative and less invasive tool for SN biopsy to select patients for adjuvant treatment. One potential target for NIR is the mesenchymal-epithelial transition factor (MET). This study aimed to assess MET immunoreactivity in positive SNs and to evaluate its potential diagnostic, prognostic and therapeutic value.

METHODS

In this retrospective study, positive SN samples from patients with primary cutaneous melanoma were collected to assess MET immunoreactivity. To this end, paraffin-embedded SNs were stained for MET (monoclonal antibody D1C2). A 4-point Histoscore was used to determine cytoplasmic and membranous immunoreactivity (0 negative/1 weak/2 moderate/3 strong). Samples were considered positive when ≥10% of the cancer cells showed MET expression (staining intensity ≥1). Patient and clinicopathological characteristics were used for descriptive statistics, binary logistic regression, and survival analyses.

RESULTS

Positive MET immunohistochemistry was observed in 24 out of 37 samples (65%). No statistically significant associations were found between MET positivity and the following prognostic factors: Breslow thickness (P = 0.961), ulceration (P = 1.000), and SN tumor burden (P = 0.792). According to MET positivity, Kaplan-Meier curves showed no significant differences in survival.

CONCLUSION

This exploratory study found no evidence to support MET immunoreactivity in positive SNs as a possible diagnostic or prognostic indicator in patients with melanoma.

KCNN4-mediated Ca2+/MET/AKT axis is promising for targeted therapy of pancreatic ductal adenocarcinoma

As a member of the potassium calcium-activated channel subfamily, increasing evidence suggests that KCNN4 was associated with malignancies. However, the roles and regulatory mechanisms of KCNN4 in PDAC have been little explored. In this work, we demonstrated that the level of KCNN4 in PDAC was abnormally elevated, and the overexpression of KCNN4 was induced by transcription factor AP-1. KCNN4 was closely correlated with unfavorable clinicopathologic characteristics and poor survival. Functionally, we found that overexpression of KCNN4 promoted PDAC cell proliferation, migration and invasion. Conversely, the knockdown of KCNN4 attenuated the growth and motility of PDAC cells. In addition to these, knockdown of KCNN4 promoted PDAC cell apoptosis and led to cell cycle arrest in the S phase. In mechanistic investigations, RNA-sequence revealed that the MET-mediated AKT axis was essential for KCNN4, encouraging PDAC cell proliferation and migration. Collectively, these findings reveal a function of KCNN4 in PDAC and suggest it's an attractive therapeutic target and tumor marker. Our studies underscore a better understanding of the biological mechanism of KCNN4 in PDAC and suggest novel strategies for cancer therapy.

A novel fluorescent c-met targeted imaging agent for intra-operative colonic tumour mapping: Translation from the laboratory into a clinical trial

BACKGROUND

The c-Met protein is overexpressed in many gastrointestinal cancers. We explored EMI-137, a novel c-Met targeting fluorescent probe, for application in fluorescence-guided colon surgery, in HT-29 colorectal cancer (CRC) cell line and an in vivo murine model.

METHODS

HT-29 SiRNA transfection confirmed specificity of EMI-137 for c-Met. A HT-29 CRC xenograft model was developed in BALB/c mice, EMI-137 was injected and biodistribution analysed through in vivo fluorescent imaging. Nine patients, received a single intravenous EMI-137 bolus (0.13 mg/kg), 1-3 h before laparoscopic-assisted colon cancer surgery (NCT03360461). Tumour and LN fluorescence was assessed intraoperatively and correlated with c-Met expression in eight samples by immunohistochemistry.

FINDINGS

c-Met expression HT-29 cells was silenced and imaged with EMI-137. Strong EMI-137 uptake in tumour xenografts was observed up to 6 h post-administration. At clinical trial, no serious adverse events related to EMI-137 were reported. Marked background fluorescence was observed in all participants, 4/9 showed increased tumour fluorescence over background; 5/9 had histological LN metastases; no fluorescent LN were detected intraoperatively. All primary tumours (8/8) and malignant LN (15/15) exhibited high c-Met protein expression.

INTERPRETATION

EMI-137, binds specifically to the human c-Met protein, is safe, and with further refinement, shows potential for application in fluorescence-guided surgery.

Anlotinib suppresses metastasis and multidrug resistance via dual blockade of MET/ABCB1 in colorectal carcinoma cells

Anlotinib, a highly selective multi-targeted tyrosine kinase inhibitor (TKI) has therapeutic effects on non-small-cell lung cancer (NSCLC). In this study, the anti-tumor activity and molecular mechanism of anlotinib in metastatic colorectal cancer (mCRC) was explored. The anti-angiogenesis, anti-metastasis, anti-proliferative, and anti-multidrug resistance efficacy of anlotinib were analyzed by using in vitro and in vivo models of human CRC cells. The results indicated that anlotinib boosted chemo-sensitivity of CRC cells, and restrained its proliferation. Besides the suppression of the MET signaling pathway, anlotinib also inhibited invasion and migration of CRC cells. Furthermore, anlotinib prevented VEGF-induced angiogenesis, N-cadherin (CDH2)-induced cell migration, and reversed ATP-binding cassette subfamily B member 1 (ABCB1) -mediated CRC multidrug resistance in CRC. The CRC liver metastasis and subcutaneously implanted xenograft model testified that anlotinib could inhibit proliferation and liver metastasis in CRC cells. Such an observation suggested that a combination of anlotinib with anti-cancer drugs could attenuate angiogenesis, metastasis, proliferative, and multidrug resistance, which constitutes a novel treatment strategy for CRC patients with metastasis.

CYP1A2 suppresses hepatocellular carcinoma through antagonizing HGF/MET signaling

Rationale: Hyperactivation of HGF/MET signaling pathway is a critical driver in liver tumorigenesis. Cytochrome P450 1A2 (CYP1A2) was significantly down-regulated in hepatocellular carcinoma (HCC). However, little is explored about its tumor suppressive role in HCC. In this study, we examined the functional mechanisms and clinical implication of CYP1A2 in HCC. Methods: The clinical impact of CYP1A2 was evaluated in HCC patients in Hong Kong cohort. The biological functions of CYP1A2 were investigated in vitro and in vivo. A series of biochemical experiments including Western blot assay, immunohistochemistry, quantitative reverse transcription-polymerase chain reaction, and Co-immunoprecipitation assay were conducted. Results: CYP1A2 expression was prominently silenced in HCC tumor tissues and the high expression of CYP1A2 was significantly correlated with lower AFP level, less vascular invasion, and better tumor-free survival in local cohort of HCC patients. The overexpression of CYP1A2 inhibited HCC cell viability and clonogenicity, reduced cell migration and invasion abilities in vitro, and suppressed tumorigenicity in vivo, whereas CYP1A2 knockdown exhibited the opposite effects. CYP1A2 significantly hindered HGF/MET signaling and Matrix metalloproteinases (MMPs) expression in HCC cells. Mechanically, CYP1A2 decreased HGF level and diminished HIF-1α expression, both of which are recognized as key regulators of MET activation. As the transcriptional activator of MET, HIF-1α was identified as a binding partner of CYP1A2. Direct binding of CYP1A2 with HIF-1α induced ubiquitin-mediated degradation of HIF-1α, inhibiting HIF-1α-mediated transcriptions. Conclusions: In conclusion, our results have identified CYP1A2 as a novel antagonist of HGF/MET signaling, and CYP1A2 may serve as an independent new biomarker for the prognosis of HCC patients.

A novel peptide targeting c-Met for hepatocellular carcinoma diagnosis

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors with limited diagnosis. Mesenchymal epithelial transition factor (c-Met) has become a hot target for cancer diagnosis and therapy, which is overexpressed in HCC. In this study, we labeled a novel c-Met targeting peptide YQ-M3 with a near-infrared fluorescent dye MPA and a radionuclide technetium-99m for HCC detection. YQ-M3-MPA showed high affinity for c-Met positive HepG2 tumor in vitro and higher tumor uptake and higher T/N ratio than GE137-MPA (a positive tracer for c-Met) in HepG2 tumor-bearing mice in vivo by fluorescence imaging. In addition, 99mTc-HYNIC-YQ-M3 also showed significant tumor uptake in vivo through SPECT imaging. These results indicated that c-Met positive tumors were successfully detected via fluorescence and SPECT imaging using YQ-M3-MPA and 99mTc-HYNIC-YQ-M3, respectively, and further suggested that YQ-M3-MPA and 99mTc-HYNIC-YQ-M3 have some possibly potential clinical applications for HCC diagnosis.

The Optimal Imaging Window for Dysplastic Colorectal Polyp Detection Using c-Met-Targeted Fluorescence Molecular Endoscopy

Fluorescence molecular endoscopy (FME) is an emerging technique that has the potential to improve the 22% colorectal polyp detection miss-rate. We determined the optimal dose-to-imaging interval and safety of FME using EMI-137, a c-Met-targeted fluorescent peptide, in a population at high risk for colorectal cancer. Methods: We performed in vivo FME and quantification of fluorescence by multidiameter single-fiber reflectance/single-fiber fluorescence spectroscopy in 15 patients with a dysplastic colorectal adenoma. EMI-137 was intravenously administered (0.13 mg/kg) at a 1-, 2- or 3-h dose-to-imaging interval (n = 3 patients per cohort). Two cohorts were expanded to 6 patients on the basis of target-to-background ratios. Fluorescence was correlated to histopathology and c-Met expression. EMI-137 binding specificity was assessed by fluorescence microscopy and in vitro experiments. Results: FME using EMI-137 appeared to be safe and well tolerated. All dose-to-imaging intervals showed significantly higher fluorescence in the colorectal lesions than in surrounding tissue, with a target-to-background ratio of 1.53, 1.66, and 1.74 for the 1-, 2-, and 3-h cohorts, respectively, and a mean intrinsic fluorescence of 0.035 vs. 0.023 mm^-1 (P < 0.0003), 0.034 vs. 0.021 mm^-1 (P < 0.0001), and 0.033 vs. 0.019 mm^-1 (P < 0.0001), respectively. Fluorescence correlated with histopathology on a macroscopic and microscopic level, with significant c-Met overexpression in dysplastic mucosa. In vitro, a dose-dependent specific binding was confirmed. Conclusion: FME using EMI-137 appeared to be safe and feasible within a 1- to 3-h dose-to-imaging interval. No clinically significant differences were observed among the cohorts, although a 1-h dose-to-imaging interval was preferred from a clinical perspective. Future studies will investigate EMI-137 for improved colorectal polyp detection during screening colonoscopies.

Optical imaging with a novel cathepsin-activatable probe for enhanced detection of colorectal cancer

We evaluated a cysteine cathepsin-activatable optical imaging probe (LUM015) with improved kinetics relative to larger macromolecules for detection and characterization of colorectal cancer (CRC), and thereby assessed its potential use in fluorescence-guided colonoscopy. We showed that LUM015 is stable in plasma. In-vitro studies demonstrated selectivity of LUM015 for targeting cathepsins; there was robust increase in emitted fluorescence signal from the cathepsin overexpressing HT-29 CRC cells within 1-5 minutes after incubation with LUM015 compared to the cells incubated with combination of LUM015 and a pan-protease inhibitor (as negative control). Biodistribution, differential accumulation of the probe in the tumor and tumor-to-background fluorescence signal ratio of LUM015 were compared to ProSense680, a commercially available protease-activatable optical imaging probe, over 24 hours after intravenous injection of the probes in nude mice with subcutaneously implanted HT-29 tumors. LUM015 showed distinct kinetics compared to ProSense680 with time to peak signal for subcutaneous tumor-to-colon ratio of 3.3±0.3 (mean ± SD) at 4-8 hours compared to 2.9±0.2 at 24 hours, respectively (n=8 for each group). Near-infrared fluorescence imaging and dual channel colonoscopy of the mice with orthotopic colon tumors showed tumor-to-colon ratio of 3.7±0.2 in HT-29 tumors (n=4), 2.8±0.1 in genetically engineered mice with APC^KOKras^LSL-G12Dp53^flox/flox mutation (n=4), and 4.1±0.1 in mice with APC^LoxP/LoxPMsh2^LoxP/LoxP mutation (n=4) at 6 hours after LUM015 administration. Immunohistochemistry and laser confocal microscopy of the extracted tumors confirmed high expression of cysteine cathepsins in all colon tumor types tested. Optical imaging with cathepsin-activatable LUM015 in multiple models of CRC highlights its potential for increasing the efficacy of CRC screening and therapeutic procedures.

PET Imaging of Receptor Tyrosine Kinases in Cancer

Overexpression and/or mutations of the receptor tyrosine kinase (RTK) subfamilies, such as epidermal growth factor receptors (EGFR) and vascular endothelial growth factor receptors (VEGFR), are closely associated with tumor cell growth, differentiation, proliferation, apoptosis, and cellular invasiveness. Monoclonal antibodies (mAb) and tyrosine kinase inhibitors (TKI) specifically inhibiting these RTKs have shown remarkable success in improving patient survival in many cancer types. However, poor response and even drug resistance inevitably occur. In this setting, the ability to detect and visualize RTKs with noninvasive diagnostic tools will greatly refine clinical treatment strategies for cancer patients, facilitate precise response prediction, and improve drug development. Positron emission tomography (PET) agents using targeted radioactively labeled antibodies have been developed to visualize tumor RTKs and are changing clinical decisions for certain cancer types. In the present review, we primarily focus on PET imaging of RTKs using radiolabeled antibodies with an emphasis on the clinical applications of these immunoPET probes. Mol Cancer Ther; 17(8); 1625-36. ©2018 AACR.

A colloidally stable water dispersion of Ni nanowires as an efficient T2-MRI contrast agent

A colloidally stable dispersion of anisotropic Ni nanowires in water has been achieved showing good performance as a T₂-contrast agent in MRI.