Isolated melanoma cells in sentinel lymph node in stage IIIA melanoma correlate with a favorable prognosis similar to stage IB.

BACKGROUND: The American Joint Committee on Cancer 8th edition (AJCC v8) defines sentinel lymph nodes (SLN) containing any tumor cells as positive SLN. Consequently, even thin melanomas with isolated tumor cells (ic) in SLN are classified as stage IIIA, making them candidates for adjuvant therapy. OBJECTIVES AND ENDPOINTS: We aimed to evaluate survival outcomes of melanoma stage IIIA (ic) and compare them with stage IIIA with lymph node (LN) metastases > 0.1 mm. Primary endpoints were relapse-free survival (RFS) and distant metastases-free survival (DMFS). Secondary endpoint was melanoma specific survival (MSS). RESULTS: The discovery cohort from the Department of Dermatology, University Hospital Tuebingen, included 237 patients; confirmation cohort included 143 patients from the DeCOG trial. The Tuebingen cohort included 95 patients with stage IIIA (ic) and 142 patients with stage IIIA. The DeCOG trial included 39 patients with stage IIIA (ic) and 104 patients with stage IIIA. In the Tuebingen cohort, 10-year RFS rates for stage IIIA (ic) and IIIA were 84% (95% CI 75-94) and 49% (95% CI 39-59), respectively (p < 0.001). 10-year DMFS rates for stage IIIA (ic) and IIIA were 89% (95% CI 81-97) and 56% (95% CI 45-67), respectively; (p < 0.001). In the DeCOG cohort, 10-year RFS for stage IIIA (ic) and stage IIIA were 88% (95% CI 78-99) and 35% (95% CI 7-62), respectively; (p = 0.009). 10-year DMFS for stage IIIA (ic) and IIIA was 88% (95% CI 77-99) and 60% (95% CI 39-80), respectively (p = 0.061). CONCLUSION: Stage IIIA (ic) melanoma exhibits a prognosis similar to stage IB. Recommendation of adjuvant therapy in Stage IIIA (ic) warrants thorough discussion.

Augmenting MEK inhibitor efficacy in BRAF wild-type melanoma: synergistic effects of disulfiram combination therapy.

BACKGROUND: MEK inhibitors (MEKi) were shown to be clinically insufficiently effective in patients suffering from BRAF wild-type (BRAF WT) melanoma, even if the MAPK pathway was constitutively activated due to mutations in NRAS or NF-1. Thus, novel combinations are needed to increase the efficacy and duration of response to MEKi in BRAF WT melanoma. Disulfiram and its metabolite diethyldithiocarbamate are known to have antitumor effects related to cellular stress, and induction of endoplasmic reticulum (ER) stress was found to synergize with MEK inhibitors in NRAS-mutated melanoma cells. Therefore, we investigated the combination of both therapeutics to test their effects on BRAF-WT melanoma cells and compared them with monotherapy using the MEKi trametinib. METHODS: The effects of combined therapy with disulfiram or its metabolite diethyldithiocarbamate and the MEKi trametinib were evaluated in a series of BRAF-WT melanoma cell lines by measuring cell viability and apoptosis induction. Cytotoxicity was additionally assessed in 3D spheroids, ex vivo melanoma slice cultures, and in vivo xenograft mouse models. The response of melanoma cells to treatment was studied at the RNA and protein levels to decipher the mode of action. Intracellular and intratumoral copper measurements were performed to investigate the role of copper ions in the antitumor cytotoxicity of disulfiram and its combination with the MEKi. RESULTS: Diethyldithiocarbamate enhanced trametinib-induced cytotoxicity and apoptosis induction in 2D and 3D melanoma culture models. Mechanistically, copper-dependent induction of oxidative stress and ER stress led to Janus kinase (JNK)-mediated apoptosis in melanoma cells. This mechanism was also detectable in patient-derived xenograft melanoma models and resulted in a significantly improved therapeutic effect compared to monotherapy with the MEKi trametinib. CONCLUSIONS: Disulfiram and its metabolite represent an attractive pharmaceutical approach to induce ER stress in melanoma cells that potentiates the antitumor effect of MEK inhibition and may be an interesting candidate for combination therapy of BRAF WT melanoma.

Therapeutic Efficacy of Pharmacological Ascorbate on Braf Inhibitor Resistant Melanoma Cells In Vitro and In Vivo.

High-dose ascorbate paradoxically acts as a pro-oxidant causing the formation of hydrogen peroxide in an oxygen dependent manner. Tumor cells (in particular melanoma cells) show an increased vulnerability to ascorbate induced reactive oxygen species (ROS). Therefore, high-dose ascorbate is a promising pharmacological approach to treating refractory melanomas, e.g., with secondary resistance to targeted BRAF inhibitor therapy. BRAF mutated melanoma cells were treated with ascorbate alone or in combination with the BRAF inhibitor vemurafenib. Viability, cell cycle, ROS production, and the protein levels of phospho-ERK1/2, GLUT-1 and HIF-1α were analyzed. To investigate the treatment in vivo, C57BL/6NCrl mice were subcutaneously injected with D4M.3A (BrafV600E) melanoma cells and treated with intraperitoneal injections of ascorbate with or without vemurafenib. BRAF mutated melanoma cell lines either sensitive or resistant to vemurafenib were susceptible to the induction of cell death by pharmacological ascorbate. Treatment of BrafV600E melanoma bearing mice with ascorbate resulted in plasma levels in the pharmacologically active range and significantly improved the therapeutic effect of vemurafenib. We conclude that intravenous high-dose ascorbate will be beneficial for melanoma patients by interfering with the tumor's energy metabolism and can be safely combined with standard melanoma therapies such as BRAF inhibitors without pharmacological interference.

Disulfiram as a Therapeutic Agent for Metastatic Malignant Melanoma-Old Myth or New Logos?

New therapeutic concepts such as anti-PD-1-based immunotherapy or targeted therapy with BRAF and MEK inhibitors have significantly improved the survival of melanoma patients. However, about 20% of patients with targeted therapy and up to 50% with immunotherapies do not respond to their first-line treatment or rapidly develop resistance. In addition, there is no approved targeted therapy for certain subgroups, namely BRAF wild-type melanomas, although they often bear aggressive tumor biology. A repurposing of already approved drugs is a promising strategy to fill this gap, as it will result in comparatively low costs, lower risks and time savings. Disulfiram (DSF), the first drug to treat alcoholism, which received approval from the US Food and Drug Administration more than 60 years ago, is such a drug candidate. There is growing evidence that DSF has great potential for the treatment of various human cancers, including melanoma. Several mechanisms of its antitumor activity have been identified, amongst them the inhibition of the ubiquitin-proteasome system, the induction of reactive oxygen species and various death signaling pathways. This article provides an overview of the application of DSF in humans, its molecular mechanisms and targets in cancer therapy with a focus on melanoma. The results of clinical studies and experimental combination approaches of DSF with various cancer therapies are discussed, with the aim of exploring the potential of DSF in melanoma therapy.

Wnt-signaling enhances neural crest migration of melanoma cells and induces an invasive phenotype.

BACKGROUND: During embryonic development Wnt family members and bone morphogenetic proteins (BMPs) cooperatively induce epithelial-mesenchymal transition (EMT) in the neural crest. Wnt and BMPs are reactivated during malignant transformation in melanoma. We previously demonstrated that the BMP-antagonist noggin blocked the EMT phenotype of melanoma cells in the neural crest and malignant invasion of melanoma cells in the chick embryo; vice-versa, malignant invasion was induced in human melanocytes in vivo by pre-treatment with BMP-2. RESULTS: Although there are conflicting results in the literature about the role of ß-catenin for invasion of melanoma cells, we found Wnt/ß-catenin signaling to be analogously important for the EMT-like phenotype of human metastatic melanoma cells in the neural crest and during invasion: ß-catenin was frequently expressed at the invasive front of human primary melanomas and Wnt3a expression was inversely correlated with survival of melanoma patients. Accordingly, cytoplasmic ß-catenin levels were increased during invasion of melanoma cells in the rhombencephalon of the chick embryo. Fibroblast derived Wnt3a reduced melanoma cell adhesion and enhanced migration, while the ß-catenin inhibitor PKF115-584 increased adhesion and reduced migration in vitro and in the chick embryonic neural crest environment in vivo. Similarly, knockdown of ß-catenin impaired intradermal melanoma cell invasion and PKF115-584 efficiently reduced liver metastasis in a chick chorioallantoic membrane model. Our observations were accompanied by specific alterations in gene expression which are linked to overall survival of melanoma patients. CONCLUSION: We present a novel role for Wnt-signaling in neural crest like melanoma cell invasion and metastasis, stressing the crucial role of embryonic EMT-inducing neural crest signaling for the spreading of malignant melanoma.

Immunotherapy in managing metastatic melanoma: which treatment when?

INTRODUCTION: Ten to fifteen percent of melanoma patients develop distant or unresectable metastasis requiring systemic treatment. Around 45% of the patients diagnosed with metastatic cutaneous melanoma harbor a BRAFV600 mutation and derive benefit from combined targeted therapy with MAPK pathway inhibitors. These offer a rapid response that translates into improvement of symptoms and increased quality of life. However, resistance often develops with subsequent progressive disease. Immunotherapy with checkpoint inhibitors may be offered to BRAF-mutated and wild-type patients and is associated with longer and durable responses that can continue over years. Areas covered: In this review, the authors discuss the late evidence for targeted and immunotherapy in melanoma patients, as well as therapy sequencing. Immunotherapy in special populations is also addressed. Expert opinion: Effective treatments are currently available. However, there are still unanswered questions of the best therapy sequence, the clear superiority of combined immunotherapy versus monotherapy in all patients, and therapy duration. Since different promising treatments will become available, clinical trials comparing the diverse options in terms of safety, efficacy and cost- effectiveness are required to make the right decisions. Consequently, patients should be encouraged to participate in clinical trials, whenever possible.