c-Met, epidermal growth factor receptor, and insulin-like growth factor-1 receptor are important for growth in uveal melanoma and independently contribute to migration and metastatic potential

The combination of PAC-1 and entrectinib for the treatment of metastatic uveal melanoma

The treatment of metastatic uveal melanoma remains a major clinical challenge. Procaspase-3, a proapoptotic protein and precursor to the key apoptotic executioner caspase-3, is overexpressed in a wide range of malignancies, and the drug PAC-1 leverages this overexpression to selectively kill cancer cells. Herein, we investigate the efficacy of PAC-1 against uveal melanoma cell lines and report the synergistic combination of PAC-1 and entrectinib. This preclinical activity, tolerability data in mice, and the known clinical effectiveness of these drugs in human cancer patients led to a small Phase 1b study in patients with metastatic uveal melanoma. The combination of PAC-1 and entrectinib was tolerated with no treatment-related grade ≥3 toxicities in these patients. The pharmacokinetics of entrectinib were not affected by PAC-1 treatment. In this small and heavily pretreated initial cohort, stable disease was observed in four out of six patients, with a median progression-free survival of 3.38 months (95% CI 1.6-6.5 months). This study is an initial demonstration that the combination of PAC-1 and entrectinib may warrant further clinical investigation. Clinical trial registration: Clinical Trials.gov: NCT04589832.

The multi-kinase inhibitor afatinib serves as a novel candidate for the treatment of human uveal melanoma

PURPOSE

Uveal melanoma (UM) is the most common intraocular malignancy in adults with a poor prognosis and a high recurrence rate. Currently there is no effective treatment for UM. Multi-kinase inhibitors targeting dysregulated pro-tumorigenic signalling pathways have revolutionised anti-cancer treatment but, as yet, their efficacy in UM has not been established. Here, we identified the multi-kinase inhibitor afatinib as a highly effective agent that exerts anti-UM effects in in vitro, ex vivo and in vivo models.

METHODS

We assessed the anti-cancer effects of afatinib using cell viability, cell death and cell cycle assays in in vitro and ex vivo UM models. The signaling pathways involved in the anti-UM effects of afatinib were evaluated by Western blotting. The in vivo activity of afatinib was evaluated in UM xenograft models using tumour mass measurement, PET scan, immunohistochemical staining and TUNEL assays.

RESULTS

We found that afatinib reduced cell viability and activated apoptosis and cell cycle arrest in multiple established UM cell lines and in patient tumour-derived primary cell lines. Afatinib impaired cell migration and enhanced reproductive death in these UM cell models. Afatinib-induced cell death was accompanied by activation of STAT1 expression and downregulation of Bcl-xL and cyclin D1 expression, which control cell survival and cell cycle progression. Afatinib attenuated HER2-AKT/ERK/PI3K signalling in UM cell lines. Consistent with these observations, we found that afatinib suppressed tumour growth in UM xenografted mice.

CONCLUSION

Our data indicate that afatinib activates UM cell death and targets the HER2-mediated cascade, which modulates STAT1-Bcl-xL/cyclin D1 signalling. Thus, targeting HER2 with agents like afatinib may be a novel therapeutic strategy to treat UM and to prevent metastasis.

Characterization of Extracellular vesicles isolated from different Liquid biopsies of uveal melanoma patients

Purpose:

Uveal melanoma (UM) is the most common intraocular malignant tumor in adults. Extracellular vesicles (EVs) have been extensively studied as a biomarker to monitor disease in patients. The study of new biomarkers in melanoma patients could prevent metastasis by earlier diagnosis. In this study, we determined the proteomic profile of EVs isolated from aqueous humor (AH), vitreous humor (VH), and plasma from UM patients in comparison with cancer-free control patients.

Methods:

AH, VH and plasma were collected from seven patients with UM after enucleation; AH and plasma were collected from seven cancer-free patients with cataract (CAT; control group). EVs were isolated using the membrane-based affinity binding column method. Nanoparticle tracking analysis (NTA) was performed to determine the size and concentration of EVs. EV markers, CD63 and TSG101, were assessed by immunoblotting, and the EV proteome was characterized by mass spectrometry.

Results:

Mean EV concentration was higher in all analytes of UM patients compared to those in the CAT group. In the UM cohort, the mean concentration of EVs was significantly lower in AH and plasma than in VH. In contrast, the mean size and size distribution of EVs was invariably identical in all analyzed analytes and in both studied groups (UM vs. CAT). Mass spectrometry analyses from the different analytes from UM patients showed the presence of EV markers.

Conclusion:

EVs isolated from AH, VH, and plasma from patients with UM showed consistent profiles and support the use of blood to monitor UM patients as a noninvasive liquid biopsy.

Intravitreal aflibercept combined with transpupillary thermotherapy in the treatment of refractory macular edema due to primary uveal melanoma

We reported a 74 year old Asian female with a uveal tumor with subretinal fluid (SRF) and cystoid macula edema. Since she declined biopsy, multimodal imaging study was performed, including fundus photography, ultrasonography, optical coherence tomography, fluorescein angiography, and magnetic resonance imaging. Uveal melanoma was diagnosed. However, despite aggressive treatment with TTT and three adjuvant intravitreal bevacizumab doses, SRF, and cystoid macula edema were persistent. Therefore, aflibercept was administered, resulting in anatomical and functional improvement within 1 month, which lasted for 12 months. Aflibercept offered great efficacy in improving refractory macular edema in this case of primary uveal melanoma. Multimodal imaging can provide us with more diagnostic clues in differentiating the nature of intraocular tumors.

The Role of HGF/MET Signaling in Metastatic Uveal Melanoma

Simple Summary

Hepatocyte growth factor (HGF)/mesenchymal-epithelial transition factor (MET) signaling plays an important role in the metastatic formation and therapeutic resistance to uveal melanoma. Here, we review the various functions of MET signaling contributing to metastatic formation, as well as review resistance to treatments in metastatic uveal melanoma.

Abstract

Hepatocyte growth factor (HGF)/mesenchymal-epithelial transition factor (MET) signaling promotes tumorigenesis and tumor progression in various types of cancer, including uveal melanoma (UM). The roles of HGF/MET signaling have been studied in cell survival, proliferation, cell motility, and migration. Furthermore, HGF/MET signaling has emerged as a critical player not only in the tumor itself but also in the tumor microenvironment. Expression of MET is frequently observed in metastatic uveal melanoma and is associated with poor prognosis. It has been reported that HGF/MET signaling pathway activation is the major mechanism of treatment resistance in metastatic UM (MUM). To achieve maximal therapeutic benefit in MUM patients, it is important to understand how MET signaling drives cellular functions in uveal melanoma cells. Here, we review the HGF/MET signaling biology and the role of HGF/MET blockades in uveal melanoma.

Dual Targeting of CDK4/6 and cMET in Metastatic Uveal Melanoma

Simple Summary

Up to 50% of uveal melanoma patients subsequently develop metastases, for which no effective treatment has been identified. In this study, 87.5% of uveal melanoma patients’ samples were positive for phosphorylated retinoblastoma (RB), and ex vivo incubation of patients’ biopsy specimens with CDK4/6 inhibitor decreased the phosphorylation of RB. Hepatocyte growth factor (HGF), which is rich in the liver microenvironment, diminished the efficacy of CDK4/6 inhibitor. In human HGF knock-in NOD.Cg-Prkdc scid Il2rg tm1Wjl/SzJ mice, combination of CDK4/6 inhibitor and cMET inhibitor showed significant growth suppression in implanted metastatic uveal melanoma cells, compared to CDK4/6 inhibitor alone. Taken together, our preclinical study indicated that combining CDK4/6 inhibitor and cMET inhibitor would provide significant clinical benefit to patients with metastatic uveal melanoma.

Abstract

Uveal melanoma (UM) is the most common cancer of the eye in adults. Up to 50% of UM patients subsequently develop metastases, especially in the liver. It has been reported that the retinoblastoma (RB) pathway is deregulated in more than 90% of UM despite the rarity of mutations in the RB1 gene itself. CDK4/6 inhibition (CDK4/6i) is a rational strategy for treatment of UM. In this report, we investigated the antiproliferative activity of a selective CDK4/6 inhibitor on metastatic UM. A CDK4/6 inhibitor suppressed UM cell lines growth in in vitro and in vivo experiments. Hepatocyte growth factor (HGF) decreased the effect of CDK4/6 inhibitor on metastatic UM cell lines. When CDK4/6i was combined with cMET inhibitor, enhanced growth suppression was observed in metastatic UM tumors grown in human-HGF knock-in xenograft mouse models. HGF is enriched in the liver and the majority of liver metastases from UM express activated forms of cMET; therefore, signaling through cMET could contribute to the resistance mechanisms against CDK4/6i, especially in UM patients with hepatic metastasis. Together, these results provide a rationale for the use of cMET inhibitor in combination with a CDK4/6 inhibitor for the treatment of metastatic UM.

Transcriptional analysis of metastatic uveal melanoma survival nominates NRP1 as a therapeutic target

Uveal melanoma is a rare form of melanoma with particularly poor outcomes in the metastatic setting. In contrast with cutaneous melanoma, uveal melanoma lacks BRAF mutations and demonstrates very low response rates to immune-checkpoint blockade. Our objectives were to study the transcriptomics of metastatic uveal melanoma with the intent of assessing gene pathways and potential molecular characteristics that might be nominated for further exploration as therapeutic targets. We initially analyzed transcriptional data from The Cancer Genome Atlas suggesting PI3K/mTOR and glycolysis as well as IL6 associating with poor survival. From tumor samples collected in a prospective phase II trial (A091201), we performed a transcriptional analysis of human metastatic uveal melanoma observing a novel role for epithelial-mesenchymal transition associating with survival. Specifically, we nominate and describe initial functional validation of neuropillin-1 from uveal melanoma cells as associated with poor survival and as a mediator of proliferation and migration for uveal melanoma in vitro. These results immediately nominate potential next steps in clinical research for patients with metastatic uveal melanoma.

Transcriptome Profiling Reveals New Insights into the Immune Microenvironment and Upregulation of Novel Biomarkers in Metastatic Uveal Melanoma

Simple Summary

Uveal melanoma (UM) is a rare aggressive eye cancer. Although treatment of the eye tumour is successful, about 50% of UM patients develop a relapse of their cancer in the liver. At present, such advanced disease is not curable. A better understanding of the metastatic UM (mUM) in the liver is essential to improve patient survival. This study examines both the response of immune cells within the liver to the UM secondaries (metastases), as well as the expression of various proteins by the UM cells. Our study demonstrates that there is a limited immune response to the mUM, but reveals that a certain type of reactive immune cell: a protumourigenic subset of macrophage is dominant within the mUM. Our research also reveals novel proteins within the mUM, which are specific to these cells and therefore may be targetable in future therapies.

Abstract

Metastatic uveal melanoma (mUM) to the liver is incurable. Transcriptome profiling of 40 formalin-fixed paraffin-embedded mUM liver resections and 6 control liver specimens was undertaken. mUMs were assessed for morphology, nuclear BAP1 (nBAP1) expression, and their tumour microenvironments (TME) using an “immunoscore” (absent/altered/high) for tumour-infiltrating lymphocytes (TILs) and macrophages (TAMs). Transcriptomes were compared between mUM and control liver; intersegmental and intratumoural analyses were also undertaken. Most mUM were epithelioid cell-type (75%), amelanotic (55%), and nBAP1-ve (70%). They had intermediate (68%) or absent (15%) immunoscores for TILs and intermediate (53%) or high (45%) immunoscores for TAMs. M2-TAMs were dominant in the mUM-TME, with upregulated expression of ANXA1, CD74, CXCR4, MIF, STAT3, PLA2G6, and TGFB1. Compared to control liver, mUM showed significant (p < 0.01) upregulation of 10 genes: DUSP4, PRAME, CD44, IRF4/MUM1, BCL2, CD146/MCAM/MUC18, IGF1R, PNMA1, MFGE8/lactadherin, and LGALS3/Galectin-3. Protein expression of DUSP4, CD44, IRF4, BCL-2, CD146, and IGF1R was validated in all mUMs, whereas protein expression of PRAME was validated in 10% cases; LGALS3 stained TAMs, and MFGEF8 highlighted bile ducts only. Intersegmental mUMs show differing transcriptomes, whereas those within a single mUM were similar. Our results show that M2-TAMs dominate mUM-TME with upregulation of genes contributing to immunosuppression. mUM significantly overexpress genes with targetable signalling pathways, and yet these may differ between intersegmental lesions.

Clinicopathological and prognostic significance and molecular mechanisms governing uveal melanoma

Uveal melanoma (UM) is the most common primary intraocular malignancy in adults. Although UM and cutaneous melanoma are derived from melanocytes, UM differs clinically and biologically from its more common skin counterparts. More than half of primary UMs metastasize. However, there is currently no effective treatment for metastatic UM. Therefore, studying mutations related to the metastasis, growth, proliferation, and survival of UM can help researchers understand its pathogenesis and metastatic mechanism, thereby leading to a more effective treatment. In addition, we provide an overview of the recent basic and clinical studies to provide a strong foundation for developing novel anti-carcinogenesis targets for future interventions.

The Role of Immune Checkpoint Blockade in Uveal Melanoma

Uveal melanoma (UM) represents the most common intraocular malignancy in adults and accounts for about 5% of all melanomas. Primary disease can be effectively controlled by several local therapy options, but UM has a high potential for metastatic spread, especially to the liver. Despite its clinical and genetic heterogeneity, therapy of metastatic UM has largely been adopted from cutaneous melanoma (CM) with discouraging results until now. The introduction of antibodies targeting CTLA-4 and PD-1 for immune checkpoint blockade (ICB) has revolutionized the field of cancer therapy and has achieved pioneering results in metastatic CM. Thus, expectations were high that patients with metastatic UM would also benefit from these new therapy options. This review provides a comprehensive and up-to-date overview on the role of ICB in UM. We give a summary of UM biology, its clinical features, and how it differs from CM. The results of several studies that have been investigating ICB in metastatic UM are presented. We discuss possible reasons for the lack of efficacy of ICB in UM compared to CM, highlight the pitfalls of ICB in this cancer entity, and explain why other immune-modulating therapies could still be an option for future UM therapies.

Expression level of EGFR and MET receptors regulates invasiveness of melanoma cells

Epidermal and hepatocyte growth factors can stimulate invasive abilities of melanoma cells, while treatment with combination of their receptors' (EGFR and MET, respectively) inhibitors reduces viability of these cells, as we have previously shown. Proposed therapy has potential; however, used drugs block more than one goal effectively, what raises the question about the real target of analysed inhibitors. For this reason, we analysed direct involvement of these receptors in the invasion of melanoma cells inducing EGFR and MET up‐ and down‐regulations in examined cells. Results were acquired with assays evaluating cell migration and invasion (scratch wound assay, Transwell filter‐based method and single‐cell tracking). We revealed that cells' motile abilities are increased after EGFR overexpression and decreased following EGFR and MET silencing. This outcome correlates with elevated (EGFR up‐regulation) or reduced (EGFR/MET down‐regulation) number of formed invadopodia, visualized with immunofluorescence, and their rate of proteolytic abilities, evaluated by fluorescent gelatin degradation assay, and gelatin zymography, compared to control cells. Above‐mentioned data indicate that both—EGFR and MET signalling is directly connected with melanoma cells invasion, what establishes these receptors as promising targets for anti‐cancer treatment.

Randomized Phase II Trial and Tumor Mutational Spectrum Analysis from Cabozantinib versus Chemotherapy in Metastatic Uveal Melanoma (Alliance A091201)

PURPOSE

The surface receptor MET is highly expressed on primary uveal melanoma; MET inhibitors demonstrated early clinical signals of efficacy in slowing uveal melanoma growth. The primary objective of our study was to compare the progression-free survival rate at 4 months (PFS4) of patients with uveal melanoma treated with cabozantinib or chemotherapy.

PATIENTS AND METHODS

Patients with metastatic uveal melanoma and RECIST measurable disease were randomized 2:1 to receive either cabozantinib (arm 1) versus temozolomide or dacarbazine (arm 2) with restaging imaging every two cycles. Cross-over from arm 2 to cabozantinib after progression was allowed (arm 2X). Available tumor specimens were analyzed by whole-exome sequencing (WES) and results were correlated with outcome.

RESULTS

Forty-six eligible patients were accrued with 31, 15, and 9 in arms 1, 2, and 2X, respectively. Median lines of prior therapy, including hepatic embolization, were two. Rates of PFS4 in arm 1 and arm 2 were 32.3% and 26.7% (P = 0.35), respectively, with median PFS time of 60 and 59 days (P = 0.964; HR = 0.99). Median overall survival (OS) was 6.4 months and 7.3 months (P = 0.580; HR = 1.21), respectively. Grade 3-4 Common Terminology Criteria for Adverse Events were present in 61.3%, 46.7%, and 37.5% in arms 1, 2, and 2X, respectively. WES demonstrated a mean tumor mutational burden of 1.53 mutations/Mb and did not separate OS ≤ or >1 year (P = 0.14). Known mutations were identified by WES and novel mutations were nominated.

CONCLUSIONS

MET/VEGFR blockade with cabozantinib demonstrated no improvement in PFS but an increase in toxicity relative to temozolomide/dacarbazine in metastatic uveal melanoma.

First-in-Human Phase I Study of Merestinib, an Oral Multikinase Inhibitor, in Patients with Advanced Cancer

BACKGROUND

The purpose of this nonrandomized, open-label, phase I study (NCT01285037) was to evaluate the safety and tolerability of merestinib, an oral antiproliferative and antiangiogenic kinase inhibitor, and to determine a recommended phase II dose and schedule for patients with advanced cancer.

MATERIALS AND METHODS

This was a multicenter, nonrandomized, open-label, phase I study of oral merestinib consisting of six parts: dose escalation (part A), followed by a four-cohort dose-confirmation study (part B) and subsequently a four-part dose expansion and combination safety testing of merestinib with standard doses of cetuximab (part C), cisplatin (part D), gemcitabine and cisplatin (part E), and ramucirumab (part F) in patients with specific types of advanced cancers. Safety, tolerability, antitumor activity, and pharmacokinetics were evaluated in all cohorts.

RESULTS

The dose escalation, confirmation, and expansion results support the dosing of merestinib at 120 mg once daily, based on acceptable exposure and safety at this dose. One complete response was observed in a patient with cholangiocarcinoma, and three patients with cholangiocarcinoma achieved a partial response. Overall, 60 (32%) of the 186 patients enrolled in the study had a best response of stable disease.

CONCLUSION

This study demonstrates that merestinib has a tolerable safety profile and potential anticancer activity and warrants further clinical investigation.

IMPLICATIONS FOR PRACTICE

Merestinib treatment in patients with advanced cancer demonstrated an acceptable safety profile and potential antitumor activity, supporting its future development in specific disease populations as a monotherapy and/or in combination with other therapies.

Reprogramming Cells for Synergistic Combination Therapy with Nanotherapeutics against Uveal Melanoma

Uveal melanoma (UM) is the most common primary intraocular malignant tumor in adults and around half of the patients develop metastasis and die shortly after because of the lack of effective therapies for metastatic UM. Consequently, new therapeutic approaches to this disease are welcome. In this regard, microRNAs have been shown to have a key role in neoplasia progression and have the potential to be used as therapeutic tools. In addition, in different cancers including UM, a particular microRNA signature appears that is different from healthy cells. Thus, restoring the regular levels of microRNAs could restore the normal behavior of cells. In this study, four microRNAs downregulated in UM have been chosen to reprogram cancer cells, to promote cell death or increase their sensitivity to the chemotherapeutic SN38. Furthermore, to improve the internalization, stability and/or solubility of the therapeutic molecules employed in this approach, gold nanoparticles (AuNPs) were used as carriers. Remarkably, this study found a synergistic effect when the four oligonucleotides were employed and when the chemotherapeutic drug was added.

Obstacles to improving outcomes in the treatment of uveal melanoma

The rate of advances in uveal melanoma has not kept pace with the rate of advances in cutaneous melanoma. Many patients lack access to or knowledge of specialty centers, and integrated multidisciplinary care between ophthalmology, radiation oncology, and medical oncology is far from the norm. This treatment isolation leads to limited communication about novel clinical trial opportunities. Clinical trials themselves are not widely available, and a lack of robust funding limits rapid and complete investigations. This review outlines the obstacles to success in uveal melanoma management and highlights strategies for overcoming these challenges. Cancer 2018;124:2693-2703. © 2018 American Cancer Society.

miR-148a-3p suppresses epithelial ovarian cancer progression primarily by targeting c-Met

MicroRNAs (miRNAs) are a group of small non-coding RNAs that modulate post-transcriptional gene expression. It has been demonstrated that various miRNAs may be expressed at different levels in different types of tumors. The present study assessed the role of microRNA-148a-3p (miR-148a-3p) in epithelial ovarian cancer (EOC). The results demonstrated that miR-148a-3p was decreased in EOC tissues and that a lower miRa-148-3p concentration was associated with a higher overall survival rate. Transfection of miR-148a-3p suppressed the invasive and proliferative capacity of SKOV3 cells. The induced overexpression of miR-148a-3p significantly inhibited the relative luciferase activity of the pmirGLO-c-Met-3'untranslated region compared with an empty vector. In addition, c-Met silencing led to a decrease in the invasive and proliferative capacity of EOC cells. The inhibition of miR-148a-3p did not increase the invasiveness of SKOV3 cells, even when c-Met was silenced. To the best of our knowledge, the present study is the first to demonstrate that miR-148a-3p expression is decreased in EOC cancer tissues and cell lines. The present study therefore demonstrated that miR-148a-3p may serve as a tumor suppressor in EOC by targeting c-Met.

Treatment of uveal melanoma: where are we now?

Uveal melanoma, a rare subset of melanoma, is the most common primary intraocular malignancy in adults. Despite effective primary therapy, nearly 50% of patients will develop metastatic disease. Outcomes for those with metastatic disease remain dismal due to a lack of effective therapies. The unique biology and immunology of uveal melanoma necessitates the development of dedicated management and treatment approaches. Ongoing efforts seek to optimize the efficacy of targeted therapy and immunotherapy in both the adjuvant and metastatic setting. This review provides a comprehensive, updated overview of disease biology and risk stratification, the management of primary disease, options for adjuvant therapy, and the current status of treatment strategies for metastatic disease.

The biology of uveal melanoma

Uveal melanoma (UM), a rare cancer of the eye, is distinct from cutaneous melanoma by its etiology, the mutation frequency and profile, and its clinical behavior including resistance to targeted therapy and immune checkpoint blockers. Primary disease is efficiently controlled by surgery or radiation therapy, but about half of UMs develop distant metastasis mostly to the liver. Survival of patients with metastasis is below 1 year and has not improved in decades. Recent years have brought a deep understanding of UM biology characterized by initiating mutations in the G proteins GNAQ and GNA11. Cytogenetic alterations, in particular monosomy of chromosome 3 and amplification of the long arm of chromosome 8, and mutation of the BRCA1-associated protein 1, BAP1, a tumor suppressor gene, or the splicing factor SF3B1 determine UM metastasis. Cytogenetic and molecular profiling allow for a very precise prognostication that is still not matched by efficacious adjuvant therapies. G protein signaling has been shown to activate the YAP/TAZ pathway independent of HIPPO, and conventional signaling via the mitogen-activated kinase pathway probably also contributes to UM development and progression. Several lines of evidence indicate that inflammation and macrophages play a pro-tumor role in UM and in its hepatic metastases. UM cells benefit from the immune privilege in the eye and may adopt several mechanisms involved in this privilege for tumor escape that act even after leaving the niche. Here, we review the current knowledge of the biology of UM and discuss recent approaches to UM treatment.

Exploiting receptor tyrosine kinase co-activation for cancer therapy

Studies over the past decade have shown that many cancers have evolved receptor tyrosine kinase (RTK) co-activation as a mechanism to drive tumour progression and limit the lethal effects of therapy. This review summarises the general principles of RTK co-activation and discusses approaches to exploit this phenomenon in cancer therapy and drug discovery. Computational strategies to predict kinase co-dependencies by integrating drug screening data and kinase inhibitor selectivity profiles will also be described. We offer a perspective on the implications of RTK co-activation on tumour heterogeneity and cancer evolution and conclude by surveying emerging computational and experimental approaches that will provide insights into RTK co-activation biology and deliver new developments in effective cancer therapies.

Evolving systemic targeted therapy strategies in uveal melanoma and implications for ophthalmic management: a review

Uveal melanoma (UM) is the most common primary ocular tumour in adults. Despite good local control of the primary tumour with current methods, survival after the development of metastasis has remained poor over the last 30 years. After cutaneous melanoma, UM is the most common type of melanoma, and an ongoing debate exists regarding whether these conditions should be considered separate entities, particularly in the context of targeted therapy, where many of the initial trials for patients with metatatic cutaneous melanoma excluded metastatic UM. This paper will review the recent and ongoing investigations designed to validate systemic targeted therapy and immunotherapy in patients with metastatic UM and suggests ways in which these developments may affect management of UM by ophthalmologists in the near future.

c-MET expression in primary and liver metastases in uveal melanoma

There is a pressing need for effective therapies to treat uveal melanoma. Agents that inhibit the c-MET pathway have shown promise in multiple malignancies that overexpress c-MET. Herein, we assess c-MET expression in both primary uveal melanoma and liver metastases of uveal melanoma and evaluate the association of c-MET expression with clinical and pathologic variables. We have retrospectively identified tumor samples from primary and liver metastases of uveal melanoma from 1 January 1990 to 1 January 2012. We utilized immunohistochemistry to assess c-MET expression, and two pathologists quantified c-MET expression using an H-score (product of the intensity of staining and percentage of positive cells). The Mann-Whitney U-test, Pearson's correlation, and Cox model were used as appropriate. Thirty-nine of 40 (98%) primary tumors and nine of 10 (90%) metastatic liver lesions expressed c-MET (H-score range 0-300). There was a strong association between the percentage of positive cells and the intensity of c-MET expression (P=0.007). We found no association between c-MET H-score and clinicopathologic variables such as age, sex, or stage. c-MET expression was significantly higher in metastatic compared with primary tumors (median H-score 190 vs. 30, P=0.022). c-MET is expressed in the vast majority of primary and liver metastases of uveal melanomas; however, c-MET expression did not associate with pathologic features in our cohort. Metastatic lesions have higher expression of c-MET expression than primary tumors. Clinical trials involving c-MET inhibitors deserve further study in patients with uveal melanoma in both the adjuvant and metastatic setting.

MiR-144 Inhibits Uveal Melanoma Cell Proliferation and Invasion by Regulating c-Met Expression

MicroRNAs (miRNAs) are a group endogenous small non-coding RNAs that inhibit protein translation through binding to specific target mRNAs. Recent studies have demonstrated that miRNAs are implicated in the development of cancer. However, the role of miR-144 in uveal melanoma metastasis remains largely unknown. MiR-144 was downregulated in both uveal melanoma cells and tissues. Transfection of miR-144 mimic into uveal melanoma cells led to a decrease in cell growth and invasion. After identification of two putative miR-144 binding sites within the 3' UTR of the human c-Met mRNA, miR-144 was proved to inhibit the luciferase activity inMUM-2B cells with a luciferase reporter construct containing the binding sites. In addition, the expression of c-Met protein was inhibited by miR-144. Furthermore, c-Met-mediated cell proliferation and invasion were inhibited by restoration of miR-144 in uveal melanoma cells. In conclusion, miR-144 acts as a tumor suppressor in uveal melanoma, through inhibiting cell proliferation and migration. miR-144 might serve as a potential therapeutic target in uveal melanoma patients.

IGF-1 Receptor and Adhesion Signaling: An Important Axis in Determining Cancer Cell Phenotype and Therapy Resistance

IGF-1R expression and activation levels generally cannot be correlated in cancer cells, suggesting that cellular proteins may modulate IGF-1R activity. Strong candidates for such modulation are found in cell-matrix and cell-cell adhesion signaling complexes. Activated IGF-1R is present at focal adhesions, where it can stabilize β1 integrin and participate in signaling complexes that promote invasiveness associated with epithelial mesenchymal transition (EMT) and resistance to therapy. Whether IGF-1R contributes to EMT or to non-invasive tumor growth may be strongly influenced by the degree of extracellular matrix engagement and the presence or absence of key proteins in IGF-1R-cell adhesion complexes. One such protein is PDLIM2, which promotes both cell polarization and EMT by regulating the stability of transcription factors including NFκB, STATs, and beta catenin. PDLIM2 exhibits tumor suppressor activity, but is also highly expressed in certain invasive cancers. It is likely that distinct adhesion complex proteins modulate IGF-1R signaling during cancer progression or adaptive responses to therapy. Thus, identifying the key modulators will be important for developing effective therapeutic strategies and predictive biomarkers.

ADAM10 correlates with uveal melanoma metastasis and promotes in vitro invasion

Uveal melanoma (UM) is a rare ocular tumor that may lead to deadly metastases in 50% of patients. A disintegrin and metalloproteinase (ADAM)10, ADAM17, and the HGF-receptor c-Met support invasiveness in different tumors. Here, we report that high ADAM10, MET, and, to a lesser extent, ADAM17 gene expression correlates with poor progression-free survival in UM patients (hazard ratio 2.7, 2.6, and 1.9, respectively). About 60% of primary UM expresses c-Met and/or ADAM10 proteins. Four UM cell lines display high levels of ADAM10 and ADAM17, which constitutively cleave c-Met, inducing the release of soluble c-Met. ADAM10/17 pharmacological inhibition or gene silencing reduces c-Met shedding, but has limited impact on surface c-Met, which is overexpressed. Importantly, ADAM10 silencing inhibits UM cell invasion driven by FCS or HGF, while ADAM17 silencing has a limited effect. Altogether our data indicate that ADAM10 has a pro-invasive role and may contribute to UM progression.

Biology of advanced uveal melanoma and next steps for clinical therapeutics

Uveal melanoma is the most common intraocular malignancy although it is a rare subset of all melanomas. Uveal melanoma has distinct biology relative to cutaneous melanoma, with widely divergent patient outcomes. Patients diagnosed with a primary uveal melanoma can be stratified for risk of metastasis by cytogenetics or gene expression profiling, with approximately half of patients developing metastatic disease, predominately hepatic in location, over a 15-yr period. Historically, no systemic therapy has been associated with a clear clinical benefit for patients with advanced disease, and median survival remains poor. Here, as a joint effort between the Melanoma Research Foundation's ocular melanoma initiative, CURE OM and the National Cancer Institute, the current understanding of the molecular and immunobiology of uveal melanoma is reviewed, and on-going laboratory research into the disease is highlighted. Finally, recent investigations relevant to clinical management via targeted and immunotherapies are reviewed, and next steps in the development of clinical therapeutics are discussed.

[Metastasis to unusual sites]

Metastases are responsible for the majority of deaths from solid cancers. Metastatic phenomenon, complex, is a multi-step process where interactions between cells and with the microenvironment are essential. The organ tropism, that is the propensity of a cancer to metastasize to specific organs, can be explained by several mechanisms that we have described. Apart from the usual metastases, unusual sites can appear with heterogeneous clinical presentations. We describe known to date mechanisms that can explain these unusual metastasis. A summary of these locations has been realized. A rare location should always be considered in front of any atypical symptom.

Simultaneous inhibition of the HGF/MET and Erk1/2 pathways affect uveal melanoma cell growth and migration

Purpose

Nearly all primary uveal melanoma (UM) that metastasize involve the liver. Hepatocyte growth factor (HGF) is proposed to be an important microenvironmental element in attracting/supporting UM metastasis through activation of MET. The majority (>85%) of UM express mutations in the G-alpha proteins, that drive the MEK-ERK1/2 pathway. Thus, we proposed that the combination of MET and MEK inhibition would inhibit the growth and migration of G-alpha protein mutant versus non-mutant UM cells.

Methods

Western-blots demonstrated the relative protein levels of ERK1/2 and MET in UM cells. Cells were treated with the small molecule inhibitors AZD6244 (MEKi) and/or MK-8033 (METi) and downstream markers evaluated. Further studies determined the effect of combination MEKi and METi treatment on cell growth, apoptosis and migration.

Results

All G-alpha protein mutant UM cell lines express MET mRNA and protein. The level of mRNA expression correlates with protein expression. MEKi, but not METi treatment results in markedly reduced ERK1/2 phosphorylation. Either MEKi or METi treatment alone results in reduced cell proliferation, but only modest induction of apoptosis. The combination MEKi+METi results in significant reduction of proliferation in G-alpha protein mutant cells. UM cell migration was blocked by METi, but not MEKi treatment.

Conclusions

MET protein expression showed no correlation with G-alpha protein mutation status. Combining MEKi with METi treatment has added benefit to either treatment alone in reducing G-alpha protein mutant UM cell growth. Combining METi with MEKi treatment adds the effect of limiting uveal melanoma cell migration.

Crizotinib, a c-Met inhibitor, prevents metastasis in a metastatic uveal melanoma model

Uveal melanoma is the most common primary intraocular malignant tumor in adults and half of the primary tumors will develop fatal metastatic disease to the liver and the lung. Crizotinib, an inhibitor of c-Met, anaplastic lymphoma kinase (ALK), and ROS1, inhibited the phosphorylation of the c-Met receptor but not of ALK or ROS1 in uveal melanoma cells and tumor tissue. Consequently, migration of uveal melanoma cells was suppressed in vitro at a concentration associated with the specific inhibition of c-Met phosphorylation. This effect on cell migration could be recapitulated with siRNA specific to c-Met but not to ALK or ROS1. Therefore, we developed a uveal melanoma metastatic mouse model with EGFP-luciferase-labeled uveal melanoma cells transplanted by retro-orbital injections to test the effect of crizotinib on metastasis. In this model, there was development of melanoma within the eye and also metastases to the liver and lung at 7 weeks after the initial transplantation. When mice were treated with crizotinib starting 1 week after the transplantation, we observed a significant reduction in the development of metastases as compared with untreated control sets. These results indicate that the inhibition of c-Met activity alone may be sufficient to strongly inhibit metastasis of uveal melanoma from forming, suggesting crizotinib as a potential adjuvant therapy for patients with primary uveal melanoma who are at high risk for the development of metastatic disease.

Ligand-independent activation of MET through IGF-1/IGF-1R signaling

The receptor tyrosine kinase, MET, has been implicated in tumorigenesis and metastasis of many solid tumors, by multiple mechanisms, including cross talk with epidermal growth factor receptor. In this study, we examined the role of insulin-like growth factor receptor-1 (IGF-1R) signaling in MET activation, focusing on prostate cancer cells. Stimulation of the prostate cancer cell line PC3 with IGF-1 induces a delayed phosphorylation of MET at multiple sites (indicative of full activation), reaching a maximum 18 hr after IGF-1 addition. MET activation does not require the sole MET ligand hepatocyte growth factor (HGF), but does require transcription to occur. Furthermore, direct injection of IGF-1 is sufficient to induce MET activation in vivo, in a PC3 xenograft model. Pharmacologic or genetic inhibition of the tyrosine kinase, Src, abolishes MET phosphorylation, and expression of activated Src is sufficient to induce Met phosphorylation in the absence of IGF-1 stimulation. Activated MET is essential for IGF-1-mediated increased migration of PC3 cells, demonstrating an important biologic effect of IGF-1-mediated MET activation. Finally, we demonstrate that IGF-1-induced delayed MET activation occurs in multiple cell lines which express both the receptors, suggesting that IGF-1R-mediated MET activation may contribute to tumorigenic properties of multiple cancer types when both growth factor receptors are expressed. The results further suggest that MET may be activated by multiple receptor tyrosine kinase receptors, and dual targeting of these receptors may be important therapeutically.

Activity of the heat shock protein 90 inhibitor ganetespib in melanoma

Heat shock protein 90 (HSP90) is involved in the regulation of diverse biological processes such as cell signaling, proliferation and survival, and has been recently recognized as a potential target for cancer therapy. Ganetespib is a potent ATP competitive inhibitor of HSP90. Ganetespib downregulated the expression of multiple signal transducing molecules including EGFR, IGF-1R, c-Met, Akt, B-RAF and C-RAF, resulting in pronounced decrease in phosphorylation of Akt and Erk1/2 in a panel of five cutaneous melanoma cell lines including those harboring B-RAF and N-RAS mutations. Ganetespib exhibited potent antiproliferative activity on all five of these cell lines, with IC50 values between 37.5 and 84 nM. Importantly, Ganetespib is active on B-RAF mutated melanoma cells that have acquired resistance to B-RAF inhibition. Ganetespib induced apoptosis and cell cycle arrest at G1 and/or G2/M phase. Ganetespib induced cell cycle arrest was accompanied by altered expression of cyclin-dependent kinase inhibitor (CDKI) p21^Cip1 and p27^Kip1, cyclins B1, D1 and E, and/or cyclin-dependent kinases 1, 2 and 4. HSP90 is functionally important for melanoma cells and HSP90 inhibitors such as ganetespib could potentially be effective therapeutics for melanoma with various genetic mutations and acquired resistance to B-RAF inhibition.

Molecular pathology of uveal melanoma

Like other cancers, uveal melanomas (UM) are characterised by an uncontrolled, clonal, cellular proliferation, occurring as a result of numerous genetic, and epigenetic aberrations. Signalling pathways known to be disrupted in UM include: (1) the retinoblastoma pathway, probably as a result of cyclin D1 overexpression; p53 signalling, possibly as a consequence of MDM2 overexpression; and the P13K/AKT and mitogen-activated protein kinase/extracellular signal-related kinase pathway pathways that are disturbed as a result of PTEN and GNAQ/11 mutations, respectively. Characteristic chromosomal abnormalities are common and include 6p gain, associated with a good prognosis, as well as 1p loss, 3 loss, and 8q gain, which correlate with high mortality. These are identified by techniques such as fluorescence in situ hybridisation, comparative genomic hybridisation, microsatellite analysis, multiplex ligation-dependent probe amplification, and single-nucleotide polymorphisms. UM can also be categorised by their gene expression profiles as class 1 or class 2, the latter correlating with poor survival, as do BRCA1-associated protein-1 (BAP1) inactivating mutations. Genetic testing of UM has enhanced prognostication, especially when results are integrated with histological and clinical data. The identification of abnormal signalling pathways, genes and proteins in UM opens the way for target-based therapies, improving prospects for conserving vision and prolonging life.

EGFR and c-Met Cross Talk in Glioblastoma and Its Regulation by Human Cord Blood Stem Cells

Receptor tyrosine kinases (RTK) and their ligands control critical biologic processes, such as cell proliferation, migration, and differentiation. Aberrant expression of these receptor kinases in tumor cells alters multiple downstream signaling cascades that ultimately drive the malignant phenotype by enhancing tumor cell proliferation, invasion, metastasis, and angiogenesis. As observed in human glioblastoma (hGBM) and other cancers, this dysregulation of RTK networks correlates with poor patient survival. Epidermal growth factor receptor (EGFR) and c-Met, two well-known receptor kinases, are coexpressed in multiple cancers including hGBM, corroborating that their downstream signaling pathways enhance a malignant phenotype. The integration of c-Met and EGFR signaling in cancer cells indicates that treatment regimens designed to target both receptor pathways simultaneously could prove effective, though resistance to tyrosine kinase inhibitors continues to be a substantial obstacle. In the present study, we analyzed the antitumor efficacy of EGFR inhibitors erlotinib and gefitinib and c-Met inhibitor PHA-665752, along with their respective small hairpin RNAs (shRNAs) alone or in combination with human umbilical cord blood stem cells (hUCBSCs), in glioma cell lines and in animal xenograft models. We also measured the effect of dual inhibition of EGFR/c-Met pathways on invasion and wound healing. Combination treatments of hUCBSC with tyrosine kinase inhibitors significantly inhibited invasion and wound healing in U251 and 5310 cell lines, thereby indicating the role of hUCBSC in inhibition of RTK-driven cell behavior. Further, the EGFR and c-Met localization in glioma cells and hGBM clinical specimens indicated that a possible cross talk exists between EGFR and c-Met signaling pathway.

Melanoma: from mutations to medicine

Melanoma is often considered one of the most aggressive and treatment-resistant human cancers. It is a disease that, due to the presence of melanin pigment, was accurately diagnosed earlier than most other malignancies and that has been subjected to countless therapeutic strategies. Aside from early surgical resection, no therapeutic modality has been found to afford a high likelihood of curative outcome. However, discoveries reported in recent years have revealed a near avalanche of breakthroughs in the melanoma field-breakthroughs that span fundamental understanding of the molecular basis of the disease all the way to new therapeutic strategies that produce unquestionable clinical benefit. These discoveries have been born from the successful fruits of numerous researchers working in many-sometimes-related, although also distinct-biomedical disciplines. Discoveries of frequent mutations involving BRAF(V600E), developmental and oncogenic roles for the microphthalmia-associated transcription factor (MITF) pathway, clinical efficacy of BRAF-targeted small molecules, and emerging mechanisms underlying resistance to targeted therapeutics represent just a sample of the findings that have created a striking inflection in the quest for clinically meaningful progress in the melanoma field.