Five-year survival with nivolumab in previously untreated Japanese patients with advanced or recurrent malignant melanoma

Immune Regulation and Immune Therapy in Melanoma: Review with Emphasis on CD155 Signalling

Melanoma is commonly diagnosed in a younger population than most other solid malignancies and, in Australia and most of the world, is the leading cause of skin-cancer-related death. Melanoma is a cancer type with high immunogenicity; thus, immunotherapies are used as first-line treatment for advanced melanoma patients. Although immunotherapies are working well, not all the patients are benefitting from them. A lack of a comprehensive understanding of immune regulation in the melanoma tumour microenvironment is a major challenge of patient stratification. Overexpression of CD155 has been reported as a key factor in melanoma immune regulation for the development of therapy resistance. A more thorough understanding of the actions of current immunotherapy strategies, their effects on immune cell subsets, and the roles that CD155 plays are essential for a rational design of novel targets of anti-cancer immunotherapies. In this review, we comprehensively discuss current anti-melanoma immunotherapy strategies and the immune response contribution of different cell lineages, including tumour endothelial cells, myeloid-derived suppressor cells, cytotoxic T cells, cancer-associated fibroblast, and nature killer cells. Finally, we explore the impact of CD155 and its receptors DNAM-1, TIGIT, and CD96 on immune cells, especially in the context of the melanoma tumour microenvironment and anti-cancer immunotherapies.

Efficacy and advantage of immunotherapy for melanoma via intramuscular co-expression of plasmid-encoded PD-1 and CTLA-4 scFvs

Immunotherapy, in the shape of immune checkpoint inhibitors (ICIs), has completely changed the treatment of cancer. However, the increasing expense of treatment and the frequency of immune-related side effects, which are frequently associated with combination antibody therapies and Fc fragment of antibody, have limited the patient's ability to benefit from these treatments. Herein, we presented the therapeutic effects of the plasmid-encoded PD-1 and CTLA-4 scFvs (single-chain variable fragment) for melanoma via an optimized intramuscular gene delivery system. After a single injection, the plasmid-encoded ICI scFv in mouse sera continued to be above 150 ng/mL for 3 weeks and reached peak amounts of 600 ng/mL. Intramuscular delivery of plasmid encoding PD-1 and CTLA-4 scFvs significantly changed the tumor microenvironment, delayed tumor growth, and prolonged survival in melanoma-bearing mice. Furthermore, no significant toxicity was observed, suggesting that this approach could improve the biosafety of ICIs combination therapy. Overall, the expression of ICI scFvs in vivo using intramuscular plasmid delivery could potentially develop into a reliable, affordable, and safe immunotherapy technique, expanding the range of antibody-based gene therapy systems that are available.

Long-term follow-up results from KEYNOTE-041: Phase 1b study of pembrolizumab in Japanese patients with advanced melanoma

Pembrolizumab demonstrated an acceptable safety profile and promising antitumor activity in Japanese patients with advanced melanoma in the phase 1b KEYNOTE-041 (Study of Pembrolizumab [MK-3475] in Participants With Advanced Melanoma) trial. To evaluate the long-term efficacy and safety of pembrolizumab in Japanese patients with advanced melanoma in KEYNOTE-041. The current analysis reports results of additional follow-up of approximately 12 months since the initial analysis. Eligible patients had locally advanced (unresectable stage III) or metastatic (stage IV) melanoma not amenable to local therapy and had received two or fewer prior systemic therapies. Pembrolizumab 2 mg/kg was given every 3 weeks for up to 2 years or until confirmed progression or unacceptable toxicity. Primary end points included safety, tolerability, and overall response rate (ORR) per Response Evaluation Criteria in Solid Tumors version 1.1 by independent central review. The data cutoff for this analysis was August 30, 2017. Forty-two patients were followed up for a median of 22.3 months (range, 2.63-30.82 months). The ORR was 24.3% (nine of 37 evaluable patients [95% confidence interval (CI), 11.8%-41.2%]). Two patients with partial response at the time of the initial analysis achieved complete response. The median overall survival (OS) was 25.1 months (95% CI, 13.1-not reached] and the 30-month OS rate was 46.3% (95% CI, 29.8%-61.3%). The median duration of response was not reached. Treatment-related adverse events (TRAEs) were reported in 78.6% of patients; the incidence of grade 3 to 5 TRAEs was 23.8%. No additional treatment-related deaths occurred since the initial analysis. Pembrolizumab provided durable antitumor activity and an acceptable safety profile in Japanese patients with advanced melanoma.

Synergistic effect of cold gas plasma and experimental drug exposure exhibits skin cancer toxicity in vitro and in vivo

INTRODUCTION

Skin cancer is often fatal, which motivates new therapy avenues. Recent advances in cancer treatment are indicative of the importance of combination treatments in oncology. Previous studies have identified small molecule-based therapies and redox-based technologies, including photodynamic therapy or medical gas plasma, as promising candidates to target skin cancer.

OBJECTIVE

We aimed to identify effective combinations of experimental small molecules with cold gas plasma for therapy in dermato-oncology.

METHODS

Promising drug candidates were identified after screening an in-house 155-compound library using 3D skin cancer spheroids and high content imaging. Combination effects of selected drugs and cold gas plasma were investigated with respect to oxidative stress, invasion, and viability. Drugs that had combined well with cold gas plasma were further investigated in vascularized tumor organoids in ovo and a xenograft mouse melanoma model in vivo.

RESULTS

The two chromone derivatives Sm837 and IS112 enhanced cold gas plasma-induced oxidative stress, including histone 2A.X phosphorylation, and further reduced proliferation and skin cancer cell viability. Combination treatments of tumor organoids grown in ovo confirmed the principal anti-cancer effect of the selected drugs. While one of the two compounds exerted severe toxicity in vivo, the other (Sm837) resulted in a significant synergistic anti-tumor toxicity at good tolerability. Principal component analysis of protein phosphorylation profiles confirmed profound combination treatment effects in contrast to the monotherapies.

CONCLUSION

We identified a novel compound that, combined with topical cold gas plasma-induced oxidative stress, represents a novel and promising treatment approach to target skin cancer.

Effects of temozolomide on tumor mutation burden and microsatellite instability in melanoma cells

The efficacy of combination therapy with an immune checkpoint inhibitor (ICI) and cytotoxic chemotherapeutic agents has been investigated in cancer, including melanoma. Before ICIs were introduced, dacarbazine or temozolomide (TMZ) were used to treat melanoma. Several studies using glioma or colorectal cancer cells showed that TMZ can increase the tumor mutation burden (TMB) and induce mismatch repair (MMR) deficiency associated with microsatellite instability (MSI). These could increase immunoreactivity to an ICI, but this has not been evaluated in melanoma cells. We investigated the effects of TMZ on MSI status and TMB in melanoma cells. To evaluate the TMB, we performed whole-exome sequencing using genomic DNA from the human melanoma cell lines Mel18, A375, WM266-4, G361, and TXM18 before and after TMZ treatment. Polymerase chain reaction amplification of five mononucleotide repeat markers, BAT25, BAT26, NR21, NR24, and MONO27, was performed, and we analyzed changes in the MSI status. In all cell lines, the TMB was increased after TMZ treatment (the change amount of TMB with ≤ 5% variant allele frequency [VAF] was 18.0-38.3 mutations per megabase) even in the condition without obvious cytological damage. MSI after TMZ treatment was not observed in any cells. TMZ increased TMB but did not change MSI status in melanoma cells.

Long-term survival with systemic therapy in the last decade: Can melanoma be cured?

Immune checkpoint inhibitors have been shown to prolong survival of patients with several types of cancer, and the finding was first established in melanoma. Previously, systemic therapy for advanced melanoma aimed only at tumor control and palliation of symptoms. However, in recent years, some patients who received systemic therapy have achieved a complete response and survived without continuous treatment for more than several years. This review discusses the long-term survival rates achieved with currently used systemic therapies and their future perspectives. Long-term survival is currently most likely to be achieved with the use of the standard-dose combination of nivolumab plus ipilimumab, however, this regimen is associated with a high frequency of serious or persistent immune-related adverse events. Several new anti-PD-1-based combination therapies with a better risk-benefit balance are currently under development. Although the acral and mucosal subtypes tend to be less responsive to immune checkpoint inhibitors, anti-PD-1-based combination therapy should continue to be investigated for these subtypes owing to its potential for better long-term survival. With the development of efficacious immunotherapy and targeted therapy, it is important to determine the optimal duration of systemic therapy to avoid unnecessary health and financial burdens as well as to improve efforts to support long-term cancer survivors. As the goal of systemic therapy shifts from tumor control to long-term survival, in future clinical trials, long-term clinical outcomes should be evaluated to assess the benefits of novel agents.

Resistance to immune checkpoint therapies by tumour-induced T-cell desertification and exclusion: key mechanisms, prognostication and new therapeutic opportunities

Immune checkpoint therapies (ICT) can reinvigorate the effector functions of anti-tumour T cells, improving cancer patient outcomes. Anti-tumour T cells are initially formed during their first contact (priming) with tumour antigens by antigen-presenting cells (APCs). Unfortunately, many patients are refractory to ICT because their tumours are considered to be 'cold' tumours-i.e., they do not allow the generation of T cells (so-called 'desert' tumours) or the infiltration of existing anti-tumour T cells (T-cell-excluded tumours). Desert tumours disturb antigen processing and priming of T cells by targeting APCs with suppressive tumour factors derived from their genetic instabilities. In contrast, T-cell-excluded tumours are characterised by blocking effective anti-tumour T lymphocytes infiltrating cancer masses by obstacles, such as fibrosis and tumour-cell-induced immunosuppression. This review delves into critical mechanisms by which cancer cells induce T-cell 'desertification' and 'exclusion' in ICT refractory tumours. Filling the gaps in our knowledge regarding these pro-tumoral mechanisms will aid researchers in developing novel class immunotherapies that aim at restoring T-cell generation with more efficient priming by APCs and leukocyte tumour trafficking. Such developments are expected to unleash the clinical benefit of ICT in refractory patients.

The Identification and Clinical Applications of Mutated Antigens in the Era of Immunotherapy

The era of personalized cancer therapy is here. Advances in the field of immunotherapy have paved the way for the development of individualized neoantigen-based therapies that can translate into favorable treatment outcomes and fewer side effects for patients. Addressing challenges related to the identification, access, and clinical application of neoantigens is critical to accelerating the development of individualized immunotherapy for cancer patients.

Treatment of Metastatic Melanoma at First Diagnosis: Review of the Literature

Metastatic melanoma (MM) is a pathological entity with a very poor prognosis that, until a few decades ago, had a low response rate to systemic treatments. Fortunately, in the last few years, new therapies for metastatic melanoma have emerged. Currently, targeted therapy and immunotherapy are the mainstays of the therapeutic arsenal available for patients with unresectable or metastatic melanoma. However, both clinical evolution and drug efficacy in melanoma patients are very different depending on the stage at which it is diagnosed. In fact, the aggressiveness of melanoma is different depending on whether it debuts directly as metastatic disease or if what occurs is a relapse after a first diagnosis at an early stage, although the biological determinants are largely unknown. Another key aspect in the clinical management of metastatic melanoma at first diagnosis strives in the different prognosis of melanoma of unknown primary (MUP) compared to melanoma of known primary (MPK). Understanding the mechanisms behind this, and the repercussion of implementing targeted and immune therapies in this specific form is crucial for designing diagnosis and treatment decision algorithms that optimize the current strategies. In this review article, we recapitulate the information available thus far regarding the epidemiology and response to immunotherapy treatments or targeted therapy in patients diagnosed with metastatic melanoma as a first diagnosis, with especial emphasis on the emerging specific information of the subpopulation formed by MUP patients.

Exploration and validation of metastasis-associated genes for skin cutaneous melanoma

Skin cutaneous melanoma is a malignant and highly metastatic skin tumor, and its morbidity and mortality are still rising worldwide. However, the molecular mechanisms that promote melanoma metastasis are unclear. Two datasets (GSE15605 and GSE46517) were retrieved to identify the differentially expressed genes (DEGs), including 23 normal skin tissues (N), 77 primary melanoma tissues (T) and 85 metastatic melanoma tissues (M). Gene ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis were performed to explore the functions of the DEGs. We constructed protein–protein interaction network using the STRING database and Cytoscape software. Using the cytoHubba plugin of Cytoscape, we identified the most significant hub genes by five analytical methods (Degree, Bottleneck, MCC, MNC, and EPC). Hub gene expression was validated using the UALCAN website. Clinical relevance was investigated using The Cancer Genome Atlas resources. Finally, we explored the association between metastasis-associated genes and immune infiltrates through the Tumor Immune Estimation Resource (TIMER) database and performed drug–gene interaction analysis using the Drug-Gene Interaction database. A total of 294 specific genes were related to melanoma metastasis and were mainly involved in the positive regulation of locomotion, mitotic cell cycle process, and epithelial cell differentiation. Four hub genes (CDK1, FOXM1, KIF11, and RFC4) were identified from the cytoHubba plugin of Cytoscape. CDK1 was significantly upregulated in metastatic melanoma compared with primary melanoma, and high CDK1 expression was positively correlated with worse overall survival. Immune infiltration analysis revealed that CDK1 expression negatively correlated with macrophage infiltration (Rho = − 0.164, P = 2.02e−03) and positively correlated with neutrophil cells (Rho = 0.269, P = 2.72e−07) in SKCM metastasis. In addition, we identified that CDK1 had a close interaction with 10 antitumor drugs. CDK1 was identified as a hub gene involved in the progression of melanoma metastasis and may be regarded as a therapeutic target for melanoma patients to improve prognosis and prevent metastasis in the future.