Biology of advanced uveal melanoma and next steps for clinical therapeutics

Prospective Clinical and Pharmacological Evaluation of the Delcath System's Second-Generation (GEN2) Hemofiltration System in Patients Undergoing Percutaneous Hepatic Perfusion with Melphalan

Introduction

Percutaneous hepatic perfusion (PHP) with melphalan is an effective treatment for patients with hepatic metastases, but associated with high rates of bone marrow depression. To reduce systemic toxicity, improvements have been made to the filtration system. In pre-clinical studies, the Delcath System’s GEN2 filter was superior to the first-generation filters. In this clinical study, we analysed the pharmacokinetics and toxicity of PHP using the new GEN2 filter.

Methods and Materials

Starting February 2014, two prospective phase II studies were initiated in patients with hepatic metastases from ocular melanoma or colorectal cancer. In 10 PHP procedures performed in the first 7 enrolled patients, blood samples were obtained to determine filter efficiency and systemic drug exposure. PHP was performed with melphalan 3 mg/kg with a maximum of 220 mg. Complications were assessed according to CTCAE v4.03. Response was assessed according to RECIST 1.1.

Results

Pharmacokinetic analysis of blood samples showed an overall filter efficiency of 86% (range 71.1–95.5%). The mean filter efficiency decreased from 95.4% 10 min after the start of melphalan infusion to 77.5% at the end of the procedure (p = 0.051). Bone marrow depression was seen after up to 80.0% of 10 procedures, but was self-limiting and mostly asymptomatic. No hypotension-related complications or procedure-related mortality occurred.

Conclusion

The GEN2 filter has a higher melphalan filter efficiency compared to the first-generation filters and a more consistent performance. PHP with the GEN2 filter appears to have an acceptable safety profile, but this needs further validation in larger studies.

Feasibility of Ultra-High-Throughput Functional Screening of Melanoma Biopsies for Discovery of Novel Cancer Drug Combinations

Purpose: Successful development of targeted therapy combinations for cancer patients depends on first discovering such combinations in predictive preclinical models. Stable cell lines and mouse xenograft models can have genetic and phenotypic drift and may take too long to generate to be useful as a personalized medicine tool.Experimental Design: To overcome these limitations, we have used a platform of ultra-high-throughput functional screening of primary biopsies preserving both cancer and stroma cell populations from melanoma patients to nominate such novel combinations from a library of thousands of drug combinations in a patient-specific manner within days of biopsy. In parallel, patient-derived xenograft (PDX) mouse models were created and novel combinations tested for their ability to shrink matched PDXs.Results: The screening method identifies specific drug combinations in tumor cells with patterns that are distinct from those obtained from stable cell lines. Screening results were highly specific to individual patients. For patients with matched PDX models, we confirmed that individualized novel targeted therapy combinations could inhibit tumor growth. In particular, a combination of multi-kinase and PI3K/Akt inhibitors was effective in some BRAF-wild-type melanomas, and the addition of cediranib to the BRAF inhibitor PLX4720 was effective in a PDX model with BRAF mutation.Conclusions: This proof-of-concept study demonstrates the feasibility of using primary biopsies directly for combinatorial drug discovery, complementing stable cell lines and xenografts, but with much greater speed and efficiency. This process could potentially be used in a clinical setting to rapidly identify therapeutic strategies for individual patients. Clin Cancer Res; 23(16); 4680-92. ©2017 AACR.

Co-targeting HGF/cMET Signaling with MEK Inhibitors in Metastatic Uveal Melanoma

Patients with metastatic uveal melanoma usually die within 1 year of diagnosis, emphasizing an urgent need to develop new treatment strategies. The liver is the most common site of metastasis. Mitogen-activated protein kinase kinase (MEK) inhibitors improve survival in V600 BRAF-mutated cutaneous melanoma patients but have limited efficacy in patients with uveal melanoma. Our previous work showed that hepatocyte growth factor (HGF) signaling elicits resistance to MEK inhibitors in metastatic uveal melanoma. In this study, we demonstrate that expression of two BH3-only family proteins, Bim-EL and Bmf, contributes to HGF-mediated resistance to MEK inhibitors. Targeting HGF/cMET signaling with LY2875358, a neutralizing and internalizing anti-cMET bivalent antibody, and LY2801653, a dual cMET/RON inhibitor, overcomes resistance to trametinib provided by exogenous HGF and by conditioned medium from primary hepatic stellate cells. We further determined that activation of PI3Kα/γ/δ isoforms mediates the resistance to MEK inhibitors by HGF. Combination of LY2801653 with trametinib decreases AKT phosphorylation and promotes proapoptotic PARP cleavage in metastatic uveal melanoma explants. Together, our data support the notion that selectively blocking cMET signaling or PI3K isoforms in metastatic uveal melanoma may break the intrinsic resistance to MEK inhibitors provided by factors from stromal cells in the liver. Mol Cancer Ther; 16(3); 516-28. ©2017 AACR.

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.

Verteporfin induces apoptosis and eliminates cancer stem-like cells in uveal melanoma in the absence of light activation

Uveal melanoma (UM) is the most common primary ocular malignancy in adults. Currently, no beneficial systemic therapy is available; therefore, there is an urgent need for effective targeted therapeutic drugs. As verteporfin has shown anti-neoplastic activity in several types of cancers, here we hypothesized and investigated the efficacy of verteporfin against UM cells without light activation. MTS assay, flow cytometry analysis of apoptosis, Western blotting of relevant proteins, transwell migration and invasion assay, melanosphere culture, and measurement of ALDH⁺ populations, were used to evaluate the effects of verteporfin on UM cells. We found that verteporfin disrupted the interaction between YAP and TEAD4 in UM cells and decreased the expression of YAP targeted downstream genes. Verteporfin treatment decreased the cytoplasmic and nuclear levels of YAP and induced lysosome-dependent degradation of YAP protein. Verteporfin exhibited distinct inhibitory effect on the proliferation of four lines of UM cells (e.g., 92.1, Mel 270, Omm 1 and Omm 2.3), and induced apoptosis through the intrinsic pathway. Additionally, verteporfin suppressed migration and invasion of UM cells, impaired the traits of cancer stem-like cells (e.g., melanosphere formation capacity, and ALDH⁺ cell population). This study demonstrated the anti-neoplastic activity of verteporfin against UM cells in vitro, providing a rationale for evaluating this agent in clinical investigation.

Comprehensive Genetic Landscape of Uveal Melanoma by Whole-Genome Sequencing

Uveal melanoma (UM) is a rare intraocular tumor that, similar to cutaneous melanoma, originates from melanocytes. To gain insights into its genetics, we performed whole-genome sequencing at very deep coverage of tumor-control pairs in 33 samples (24 primary and 9 metastases). Genome-wide, the number of coding mutations was rather low (only 17 variants per tumor on average; range 7-28), thus radically different from cutaneous melanoma, where hundreds of exonic DNA insults are usually detected. Furthermore, no UV light-induced mutational signature was identified. Recurrent coding mutations were found in the known UM drivers GNAQ, GNA11, BAP1, EIF1AX, and SF3B1. Other genes, i.e., TP53BP1, CSMD1, TTC28, DLK2, and KTN1, were also found to harbor somatic mutations in more than one individual, possibly indicating a previously undescribed association with UM pathogenesis. De novo assembly of unmatched reads from non-coding DNA revealed peculiar copy-number variations defining specific UM subtypes, which in turn could be associated with metastatic transformation. Mutational-driven comparison with other tumor types showed that UM is very similar to pediatric tumors, characterized by very few somatic insults and, possibly, important epigenetic changes. Through the analysis of whole-genome sequencing data, our findings shed new light on the molecular genetics of uveal melanoma, delineating it as an atypical tumor of the adult for which somatic events other than mutations in exonic DNA shape its genetic landscape and define its metastatic potential.

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.

Ric-8A gene deletion or phorbol ester suppresses tumorigenesis in a mouse model of GNAQ(Q209L)-driven melanoma

The heterotrimeric G protein α subunit oncogenes GNAQ or GNA11 carry Q209X or R183X activating mutations and are present with ~90% frequency in human uveal melanomas. Forced expression of GNAQ/11^Q209L in melanocytes is sufficient to drive metastatic melanoma in immune-compromised mice. No known drugs directly target these oncogenic G proteins. Ric-8A is the molecular chaperone that selectively folds Gαq/i/13 subunits. Targeting Ric-8A serves as a rational, yet unexplored approach to reduce the functional abundance of oncogenic Gαq/11 in order to blunt cancer signaling. Here, using mouse melanocyte cell graft tumorigenesis models, we determined that Ric-8A genetic ablation attenuated the abundance and melanoma-driving potential of Gαq-Q209L. A new conditional Ric-8A^Flox/Flox; Rosa-CreER^+/− mouse strain was derived and used as a tissue source to culture an immortalized, tamoxifen-inducible Ric-8A knockout melanocyte cell line that required 12-O-tetradecanoylphorbol-13-acetate (TPA, phorbol ester) for growth. The cell line failed to grow tumors when grafted into immune-compromised mice regardless of Ric-8A expression. Stable expression of human GNAQ^Q209L, but not GNAQ^WT in the cell line promoted TPA-independent cell proliferation, and upon cell grafting in mice, the initiation and robust growth of darkly-pigmented melanoma tumors. Deletion of Ric-8A in GNAQ^Q209L cells restored TPA-dependent growth, reduced Gαq-Q209L below detectable levels and completely mitigated tumorigenesis from primary or secondary cell line grafts. Interestingly, TPA treatment of cultured GNAQ^Q209L cells or host animals grafted with GNAQ^Q209L cells also sharply reduced Gαq-Q209L abundance and tumorigenic capacity. Finally, tumorigenesis initiated from GNAQ^Q209L cell grafts, followed by host mouse systemic tamoxifen treatment to delete Ric-8A in the grafted cells completely abrogated GNAQ^Q209L-driven tumor progression unless a stable human RIC-8A transgene was used to rescue the floxed Ric-8A alleles. Our work defines two new rational targets that may be developed as potential uveal melanoma therapies through reduction of Gαq/11-Q209L oncoprotein abundance: (1) Ric-8A inhibition and (2) phorbol ester treatment.

Uveal melanoma as a target for immune-therapy

Uveal melanoma (UM) is a rare disease that can be deadly in spite of adequate local treatment. Systemic therapy with chemotherapy is usually ineffective and new-targeted therapies have not improved results considerably. The eye creates an immunosuppressive environment in order to protect eyesight. UM cells use similar processes to escape immune surveillance. Regarding innate immunity the production of macrophage inhibiting factor (MIF) and TGF-β, added to MHC class I upregulation, inhibits the action of natural killer (NK) cells. UM cells produce cytokines such as IL-6 and IL-10 that favor macrophage differentiation to the M2 subtype, which promote tumor growth instead of an effective immune response. UM cells also impair the adaptive immune response through production of indoleamine 2,3-dioxygenase (IDO), overexpression of programmed death ligand-1 (PD-L1), alteration of FasL expression, and resistance to perforin. This biological background suggests that immunotherapy could be effective in fighting UM. A Phase II clinical trial with Ipilimumab has shown promising results with mean Overall Survival rate of ten months, and close to 50% of the patients alive at one year. Clinical trials with anti-PD1 antibodies in monotherapy and in combination with anti-CTLA4 are currently recruiting patients worldwide.

Uveal Melanoma: Current Trends in Diagnosis and Management

Uveal melanoma, which is the most common primary intraocular malignancy in adults, arises from melanocytes within the iris, ciliary body and choroid. The diagnosis is based principally on clinical examination of the tumor with biomicroscopy and indirect ophthalmoscopy and confirmed by diagnostic techniques such as ultrasonography, fundus fluorescein angiography and optical coherence tomography. The clinical diagnosis of posterior uveal melanomas can be made when the classical appearance of a pigmented dome-shaped mass is detected on dilated fundus exam. Uveal melanomas classically show low to medium reflectivity on A-scan ultrasonography and on B-scan ultrasonography the tumor appears as a hyperechoic, acoustically hollow intraocular mass. Management of a suspicious pigmented lesion is determined by its risk factors of transforming into a choroidal melanoma, such as documentation of growth, thickness greater than 2 mm, presence of subretinal fluid, symptoms and orange pigment, margin within 3 mm of the optic disc, and absence of halo and drusen. Advances in the diagnosis and local and systemic treatment of uveal melanoma have caused a shift from enucleation to eye-conserving treatment modalities including transpupillary thermotherapy and radiotherapy over the past few decades. Prognosis can be most accurately predicted by genetic profiling of fine needle aspiration biopsy of the tumor before the treatment, and high-risk patients can now be identified for clinical trials that may lead to target-based therapies for metastatic disease and adjuvant therapy which aims to prevent metastatic disease.

Melanoma: Clinical Presentations

The malignant cell in melanoma is the melanocyte. Because melanocytes are located in the basal layer of the epidermis, melanoma is most commonly seen on the skin. However, melanoma can also arise on mucosal surfaces such as the oral cavity, the upper gastrointestinal mucosa, the genital mucosa, as well as the uveal tract of the eye and leptomeninges. Melanomas tend to be pigmented but can also present as pink or red lesions. They can mimic benign or other malignant skin lesions. This chapter presents the spectrum of typical and less typical presentations of melanoma, as well as patterns of spread. It is divided into (1) cutaneous lesions; (2) patterns of regional spread, (3) non-cutaneous lesions; and (4) distant metastases.

Paracrine Effect of NRG1 and HGF Drives Resistance to MEK Inhibitors in Metastatic Uveal Melanoma

Uveal melanoma patients with metastatic disease usually die within one year, emphasizing an urgent need to develop new treatment strategies for this cancer. MEK inhibitors improve survival in cutaneous melanoma patients but show only modest efficacy in metastatic uveal melanoma patients. In this study, we screened for growth factors that elicited resistance in newly characterized metastatic uveal melanoma cell lines to clinical-grade MEK inhibitors, trametinib and selumetinib. We show that neuregulin 1 (NRG1) and hepatocyte growth factor (HGF) provide resistance to MEK inhibition. Mechanistically, trametinib enhances the responsiveness to NRG1 and sustained HGF-mediated activation of AKT. Individually targeting ERBB3 and cMET, the receptors for NRG1 and HGF, respectively, overcome resistance to trametinib provided by these growth factors and by conditioned medium from fibroblasts that produce NRG1 and HGF. Inhibition of AKT also effectively reverses the protective effect of NRG1 and HGF in trametinib-treated cells. Uveal melanoma xenografts growing in the liver in vivo and a subset of liver metastases of uveal melanoma patients express activated forms of ERBB2 (the coreceptor for ERBB3) and cMET. Together, these results provide preclinical evidence for the use of MEK inhibitors in combination with clinical-grade anti-ERBB3 or anti-cMET monoclonal antibodies in metastatic uveal melanoma.