Synergy between enzastaurin doxorubicin in inducing melanoma apoptosis

Health-related quality of life during trans-arterial chemoembolization with drug-eluting beads loaded with doxorubicin (DEBDOX) for unresectable hepatic metastases from ocular melanoma

BACKGROUND

We have previously reported favorable response and survival rates using drug-eluting beads loaded with doxorubicin (DEBDOX) for unresectable hepatic metastases. This study investigates the quality of life (QoL) impact of DEBDOX for the treatment of unresectable hepatic metastases from melanoma.

METHODS

A multi-center, prospective, non-controlled clinical trial was reviewed. QoL was assessed at baseline and after each treatment, and doxorubicin-specific effects were assessed after each treatment.

RESULTS

Twenty patients received 61 DEBDOX treatments. After each treatment, at least 83% of patients reported "little" to "none" doxorubicin-related symptoms. For the 8 FACT-Hep subscales, QoL scores were unchanged through 3 treatments for 18 of 24 total time points by ANOVA, with a small-to-moderate ES change through the last treatment in 36 of 40 time points.

CONCLUSIONS

Hepatic arterial therapy with DEBDOX is safe with minimal QOL changes in treating unresectable liver-dominant melanoma metastasis.

CLINICAL TRIAL

NCT01010984.

Image-Guided Transarterial Chemoembolization With Drug-Eluting Beads Loaded with Doxorubicin (DEBDOX) for Unresectable Hepatic Metastases from Melanoma: Technique and Outcomes

PURPOSE

Hepatic metastasis from melanoma represents a therapeutic dilemma, with limited effective options for the 85% of cases deemed unresectable. Systemic agents confer toxicity and, along with traditional local hepatic arterial-directed therapies such as transarterial chemoembolization, have not led to a significant increase in survival. The aim of this study was to investigate the safety and dose-limiting toxicity of DEBDOX for the treatment of unresectable hepatic metastases from melanoma.

METHODS

A multicenter (University of Louisville, Thomas Jefferson University, MD Anderson Cancer Center), prospective, non-controlled treatment trial (NCT01010984) of hepatic-directed therapy with DEBDOX for the treatment of melanoma liver metastasis was reviewed. Primary endpoints were response rates by modified response evaluation criteria in solid tumors, hepatic progression-free survival (PFS), and overall survival (OS).

RESULTS

Twenty patients received a total of 61 DEBDOX treatments from January 2010 to March 2013. The median hepatic tumor burden was 40% (range 20-55), 18 patients (90%) had bilobar disease, and 13 patients (65%) had concomitant extrahepatic disease. At median assessment of 2.5 months, 11 patients (55%) exhibited a tumor response and 16 (80%) exhibited disease control. Median follow-up was 5 months (range 1.1-34.3 months). Median hepatic PFS was 3 months (95% CI 1.4, 3.4), and OS was 5 months (95% CI 3.3, 10.5).

CONCLUSIONS

Directed arterial therapy with DEBDOX is effective in managing unresectable liver-dominant metastasis from melanoma and should be considered a therapeutic option in the multidisciplinary treatment of this disease. Concurrent systemic therapy is merited given the high rate of extrahepatic progression.

CLINICAL TRIAL

NCT01010984.

Immune-system-dependent anti-tumor activity of a plant-derived polyphenol rich fraction in a melanoma mouse model

Recent findings suggest that part of the anti-tumor effects of several chemotherapeutic agents require an intact immune system. This is in part due to the induction of immunogenic cell death. We have identified a gallotannin-rich fraction, obtained from Caesalpinia spinosa (P2Et) as an anti-tumor agent in both breast carcinoma and melanoma. Here, we report that P2Et treatment results in activation of caspase 3 and 9, mobilization of cytochrome c and externalization of annexin V in tumor cells, thus suggesting the induction of apoptosis. This was preceded by the onset of autophagy and the expression of immunogenic cell death markers. We further demonstrate that P2Et-treated tumor cells are highly immunogenic in vaccinated mice and induce immune system activation, clearly shown by the generation of interferon gamma (IFN-γ) producing tyrosine-related protein 2 antigen-specific CD8+ T cells. Moreover, the tumor protective effects of P2Et treatment were abolished in immunodeficient mice, and partially lost after CD4 and CD8 depletion, indicating that P2Et's anti-tumor activity is highly dependent on immune system and at least in part of T cells. Altogether, these results support the hypothesis that the gallotannin-rich fraction P2Et's anti-tumor effects are mediated to a great extent by the endogenous immune response following to the exposure to immunogenic dying tumor cells.

Enzastaurin inhibits ABCB1-mediated drug efflux independently of effects on protein kinase C signalling and the cellular p53 status

The PKCβ inhibitor enzastaurin was tested in parental neuroblastoma and rhabdomyosarcoma cell lines, their vincristine-resistant sub-lines, primary neuroblastoma cells, ABCB1-transduced, ABCG2-transduced, and p53-depleted cells. Enzastaurin IC₅₀s ranged from 3.3 to 9.5 μM in cell lines and primary cells independently of the ABCB1, ABCG2, or p53 status. Enzastaurin 0.3125 μM interfered with ABCB1-mediated drug transport. PKCα and PKCβ may phosphorylate and activate ABCB1 under the control of p53. However, enzastaurin exerted similar effects on ABCB1 in the presence or absence of functional p53. Also, enzastaurin inhibited PKC signalling only in concentrations ≥ 1.25 μM. The investigated cell lines did not express PKCβ. PKCα depletion reduced PKC signalling but did not affect ABCB1 activity. Intracellular levels of the fluorescent ABCB1 substrate rhodamine 123 rapidly decreased after wash-out of extracellular enzastaurin, and enzastaurin induced ABCB1 ATPase activity resembling the ABCB1 substrate verapamil. Computational docking experiments detected a direct interaction of enzastaurin and ABCB1. These data suggest that enzastaurin directly interferes with ABCB1 function. Enzastaurin further inhibited ABCG2-mediated drug transport but by a different mechanism since it reduced ABCG2 ATPase activity. These findings are important for the further development of therapies combining enzastaurin with ABC transporter substrates.

Epigenetic marks responsible for cadmium-induced melanoma cell overgrowth

Cadmium (Cd) is a human carcinogen that likely acts via epigenetic mechanisms. However, the precise role of Cd in melanoma remains to be defined. The goals of this study are to: (i) examine the effect of Cd on the proliferation rate of cutaneous and uveal melanoma cells; (ii) identify the genes affected by Cd exposure; (iii) understand whether epigenetic changes are involved in the response to Cd. The cell growth capacity increased at 48 h after Cd treatment at doses ranging from 0.5 to 10 μM. The research on the key genes regulating proliferation has shown that aberrant methylation is responsible for silencing of p16(INK4A) and caspase 8 in uveal and cutaneous melanoma cells, respectively. The methylation and expression patterns of p14(ARF), death receptors 4/5, and E-cadherin remained unmodified after Cd treatment in all the cell lines analyzed. Ectopic expression of p16(INK4A) abolished the overgrowth of uveal melanoma cells in response to Cd and the overexpression of caspase 8 drastically increased the apoptotic rate of Cd-treated cutaneous melanoma cells. In conclusion, our data suggest that hypermethylation of p16(INK4A) and caspase 8 represents the most common event linked to Cd-induced stimulation of cell growth and inhibition of cell death pathway in melanoma.

Immune consequences of kinase inhibitors in development, undergoing clinical trials and in current use in melanoma treatment

Metastatic malignant melanoma is a frequently fatal cancer. In recent years substantial therapeutic progress has occurred with the development of targeted kinase inhibitors and immunotherapeutics. Targeted therapies often result in rapid clinical benefit however responses are seldom durable. Immune therapies can result in durable disease control but responses may not be immediate. Optimal cancer therapy requires both rapid and durable cancer control and this can likely best be achieved by combining targeted therapies with immunotherapeutics. To achieve this, a detailed understanding of the immune consequences of the various kinase inhibitors, in development, clinical trial and currently used to treat melanoma is required.

Hybrid polymeric micelles based on bioactive polypeptides as pH-responsive delivery systems against melanoma

The bioactive polymer poly(L-glutamic acid)n-b-poly(D, L-lactic acid)m was synthesized and used to form doxorubicin-loaded hybrid polymeric micelles to treat melanoma. These polymers exhibited pH-responsive changes in conformation, which controlled the diverse functionalities of the micelles. During circulation, poly(L-glutamic acid)n-b-poly(D, L-lactic acid)m protected Tat peptides on the micelles from proteolysis. Under tumor-acidic conditions, polymers with shorter poly(l-glutamic acid) blocks underwent a conformational change to form channels that accelerated the release of doxorubicin. The conformational change also exposed the Tat peptides to tumor cells, thereby promoting cellular internalization of the micelles. Enhanced cellular uptake of the micelles induced significant apoptosis of A375 melanoma cells in tumor-acidic conditions. In vivo studies demonstrated that the micelles with shorter poly(L-glutamic acid) blocks could effectively accumulate in tumor tissues, suppress tumor growth and help maintain the body weight of tumor-bearing mice. However, micelles with longer poly(l-glutamic acid) blocks did not undergo a conformational change under acidic conditions and performed poorly in both in vitro and in vivo evaluations. Our work provides a strategy for applying bioactive polymers to the rational construction of pH-responsive delivery systems for solid tumors and lends insight into possible conformational effects on the bioactivity of drug carriers.

Genomewide RNAi screen identifies protein kinase Cb and new members of mitogen-activated protein kinase pathway as regulators of melanoma cell growth and metastasis

A large-scale RNAi screen was performed for eight different melanoma cell lines using a pooled whole-genome lentiviral shRNA library. shRNAs affecting proliferation of transduced melanoma cells were negatively selected during 10 days of culture. Overall, 617 shRNAs were identified by microarray hybridization. Pathway analyses identified mitogen-activated protein kinase (MAPK) pathway members such as ERK1/2, JNK1/2 and MAP3K7 and protein kinase C β (PKCβ) as candidate genes. Knockdown of PKCβ most consistently reduced cellular proliferation, colony formation and migratory capacity of melanoma cells and was selected for further validation. PKCβ showed enhanced expression in human primary melanomas and distant metastases as compared with benign melanocytic nevi. Moreover, treatment of melanoma cells with PKCβ-specific inhibitor enzastaurin reduced melanoma cell growth but had only small effects on benign fibroblasts. Finally, PKCβ-shRNA significantly reduced lung colonization capacity of stably transduced melanoma cells in mice. Taken together, this study identified new candidate genes for melanoma cell growth and proliferation. PKCβ seems to play an important role in these processes and might serve as a new target for the treatment of metastatic melanoma.