The treatment of advanced melanoma: a review of systemic and local therapies in combination with immune checkpoint inhibitors in phase 1 and 2 clinical trials

Multifaceted approach toward mapping out the anticancer properties of small molecules via in vitro evaluation on melanoma and nonmelanoma skin cancer cells, and in silico target fishing

Melanoma and nonmelanoma skin cancers are among the most prevalent and most lethal forms of skin cancers. To identify new lead compounds with potential anticancer properties for further optimization, in vitro assays combined with in-silico target fishing and docking have been used to identify and further map out the antiproliferative and potential mode of action of molecules from a small library of compounds previously prepared in our laboratory. From screening these compounds in vitro against A375, SK-MEL-28, A431, and SCC-12 skin cancer cell lines, 35 displayed antiproliferative activities at the micromolar level, with the majority being primarily potent against the A431 and SCC-12 squamous carcinoma cell lines. The most active compounds 11 (A431: IC50  = 5.0 μM, SCC-12: IC50  = 2.9 μM, SKMEL-28: IC50  = 4.9 μM, A375: IC50  = 6.7 μM) and 13 (A431: IC50  = 5.0 μM, SCC-12: IC50  = 3.3 μM, SKMEL-28: IC50  = 13.8 μM, A375: IC50  = 17.1 μM), significantly and dose-dependently induced apoptosis of SCC-12 and SK-MEL-28 cells, as evidenced by the suppression of Bcl-2 and upregulation of Bax, cleaved caspase-3, caspase-9, and PARP protein expression levels. Both agents significantly reduced scratch wound healing, colony formation, and expression levels of deregulated cancer molecular targets including RSK/Akt/ERK1/2 and S6K1. In silico target prediction and docking studies using the SwissTargetPrediction web-based tool suggested that CDK8, CLK4, nuclear receptor ROR, tyrosine protein-kinase Fyn/LCK, ROCK1/2, and PARP, all of which are dysregulated in skin cancers, might be prospective targets for the two most active compounds. Further validation of these targets by western blot analyses, revealed that ROCK/Fyn and its associated Hedgehog (Hh) pathways were downregulated or modulated by the two lead compounds. In aggregate, these results provide a strong framework for further validation of the observed activities and the development of a more comprehensive structure-activity relationship through the preparation and biological evaluation of analogs.

Electrochemotherapy of Melanoma Cutaneous Metastases in Organ Transplant Recipients: A Systematic Review of Preclinical and Clinical Studies

Cutaneous melanoma is a highly aggressive form of skin cancer. The development of immune checkpoint inhibitors (ICIs) has revolutionized the management of advanced melanoma, led to durable responses, and improved overall survival. However, the success of ICIs in melanoma treatment is influenced by the tumor microenvironment (TME) which plays a critical role in regulating the immune response to the tumor. Understanding the mechanisms underlying this interaction is crucial to optimizing the efficiency of ICIs. Electrochemotherapy (ECT) has been shown to enhance the efficacy of ICIs in melanoma treatment by inducing tumor cell death and facilitating the release of tumor antigens which can subsequently be recognized and targeted by the immune system. Moreover, ECT has been reported to modulate the TME, leading to increased infiltration of immune cells and a more favorable immunological profile. In this review, we summarize the available knowledge of changes in TME after ECT of melanoma cutaneous metastasis and highlight the differences in tumor-infiltrating immune cells between immunocompetent and immunosuppressed organisms. In addition, we showed that ECT can be an effective and safe procedure for organ transplant recipients. Furthermore, repeated ECT may enhance immune activation and probably induce a bystander effect by trained immunity.

Oxidative Stress Differentially Influences the Survival and Metabolism of Cells in the Melanoma Microenvironment

The cellular composition of the tumor microenvironment, including tumor, immune, stromal, and endothelial cells, significantly influences responses to cancer therapies. In this study, we analyzed the impact of oxidative stress, induced by cold atmospheric plasma (CAP), on tumor cells, T cells, and macrophages, which comprise part of the melanoma microenvironment. To accomplish this, cells were grown in different in vitro cell culture models and were treated with varying amounts of CAP. Subsequent alterations in viability, proliferation, and phenotype were analyzed via flow cytometry and metabolic alterations by Seahorse Cell Mito Stress Tests. It was found that cells generally exhibited reduced viability and proliferation, stemming from CAP induced G2/M cell cycle arrest and subsequent apoptosis, as well as increased mitochondrial stress following CAP treatment. Overall, sensitivity to CAP treatment was found to be cell type dependent with T cells being the most affected. Interestingly, CAP influenced the polarization of M0 macrophages to a "M0/M2-like" phenotype, and M1 macrophages were found to display a heightened sensitivity to CAP induced mitochondrial stress. CAP also inhibited the growth and killed melanoma cells in 2D and 3D in vitro cell culture models in a dose-dependent manner. Improving our understanding of oxidative stress, mechanisms to manipulate it, and its implications for the tumor microenvironment may help in the discovery of new therapeutic targets.