Molecular Mechanisms of Resistance to Immune Checkpoint Inhibitors in Melanoma Treatment: An Update

Exploring correlations between gut mycobiome and lymphocytes in melanoma patients undergoing anti-PD-1 therapy

Research has shown that the microbiome can influence how the immune system responds to melanoma cells, affecting the course of the disease and the outcome of the therapy. Here, we used the metagenomic approach and flow cytometry analyses of blood cells to discover correlations between gut fungi of metastatic melanoma patients enrolled in anti-PD-1 therapy and lymphocytes in their blood.We analyzed the patterns of associations before the first administration of anti-PD-1 therapy (BT, n = 61) and in the third month of the therapy (T3, n = 37), allowing us to track changes during treatment. To understand the possible impact of gut fungi on the efficacy of anti-PD-1 therapy, we analyzed the associations in clinical beneficiaries (CB, n = 37) and non-beneficiaries (NB, n = 24), as well as responders (R, n = 28) and non-responders (NR, n = 33).Patients with LDH < 338 units/L, overall survival (OS) > 12, CB, as well as R, had lower levels of Shannon diversity (p = 0.02, p = 0.05, p = 0.05, and p = 0.03, respectively). We found that the correlation pattern between intestinal fungi and lymphocytes was specific to the type of response, positive or negative. When comparing CB and NB groups, correlations with opposite directions were detected for C. albicans, suggesting a response-specific immune reaction. For CB, M. restricta exhibited a set of correlations with different types of lymphocytes, with prevalent positive correlations, suggesting a robust immune response in the CB group. This result extends our former research, where M. restricta and C. albicans were associated with an increased risk of melanoma progression and a poorer response to anti-PD-1 treatment.

Rationales of Cold Plasma Jet Therapy in Skin Cancer

Skin cancer affects millions of patients worldwide, and its incidence is increasing. Current therapies targeting skin tumour subtypes, such as basal cell carcinoma, cutaneous squamous cell carcinoma, melanoma and actinic keratosis, vary in their degree of effectiveness and tolerability, motivating new research avenues on complementing treatment strategies. Cold medical gas plasma is a partially ionised gas operated at about body temperature and generates various reactive oxygen and nitrogen species simultaneously. A range of medical gas plasma devices has proven safe in thousands of patients and is an approved medical product for dermatology conditions, such as nonhealing wounds, in Europe and, more broadly, for clinical trials. Extending potential gas plasma applications in the field of dermato-oncology is therefore plausible, especially in light of the strong preclinical evidence and early clinical data. This review summarises existing work on gas plasma treatment, focusing on approved jet plasmas in skin cancer and outlining central mechanisms and treatment concepts. It also provides a concrete perspective on integrating medical gas plasma treatment into existing skin cancer therapy schemes, encouraging translational scientists and clinicians to enable gas plasma-assisted cancer care through clinical research.

Integrated Analysis of Single-Cell and Bulk RNA Data Reveals Complexity and Significance of the Melanoma Interactome

Background: Despite significant strides in anti-melanoma therapies, resistance and recurrence remain major challenges. A deeper understanding of the underlying biology of these challenges is necessary for developing more effective treatment paradigms. Methods: Melanoma single-cell data were retrieved from the Broad Single Cell Portal (SCP11). High-dimensional weighted gene co-expression network analysis (hdWGCNA), CellChat, and ligand-receptor relative crosstalk (RC) scoring were employed to evaluate intercellular and intracellular signaling. The prognostic value of key regulatory genes was assessed via Kaplan-Meier (KM) survival analysis using the 'SKCM-TCGA' dataset. Results: Twenty-seven (27) gene co-expression modules were identified via hdWGCNA. Notable findings include NRAS Q61L melanomas being enriched for modules involving C19orf10 and ARF4, while BRAF V600E melanomas were enriched for modules involving ALAS1 and MYO1B. Additionally, CellChat analysis highlighted several dominant signaling pathways, namely MHC-II, CD99, and Collagen-receptor signaling, with numerous significant ligand-receptor interactions from melanocytes, including CD99-CD99 communications with cancer-associated fibroblasts, endothelial cells, NK cells, and T-cells. KM analysis revealed that higher expression of SELL, BTLA, IL2RG, PDGFA, CLDN11, ITGB3, and SPN improved overall survival, while higher FGF5 expression correlated with worse survival. Protein-protein interaction network analysis further indicated significant interconnectivity among the identified prognostic genes. Conclusions: Overall, these insights underscore critical immune interactions and potential therapeutic targets to combat melanoma resistance, paving the way for more personalized and effective treatment strategies.

A landscape of checkpoint blockade resistance in cancer: underlying mechanisms and current strategies to overcome resistance

The discovery of immune checkpoints and the development of immune checkpoint inhibitors (ICI) have achieved a durable response in advanced-stage cancer patients. However, there is still a high proportion of patients who do not benefit from ICI therapy due to a lack of response when first treated (primary resistance) or detection of disease progression months after objective response is observed (acquired resistance). Here, we review the current FDA-approved ICI for the treatment of certain solid malignancies, evaluate the contrasting responses to checkpoint blockade in different cancer types, explore the known mechanisms associated with checkpoint blockade resistance (CBR), and assess current strategies in the field that seek to overcome these mechanisms. In order to improve current therapies and develop new ones, the immunotherapy field still has an unmet need in identifying other molecules that act as immune checkpoints, and uncovering other mechanisms that promote CBR.

Efficacy and prognostic factors of anti-PD1 and nivolumab-ipilimumab therapy in advanced melanoma patients resistant to prior ICI treatment

Immune checkpoint inhibitors (ICIs) have significantly improved the five-year survival rate for advanced melanoma. However, many patients exhibit resistance to ICI therapy. This study evaluated the efficacy and prognostic factors of anti-PD-1 (Group A) and nivolumab-ipilimumab (Group B) therapy in patients with advanced melanoma who were resistant to prior ICI therapy. We conducted a retrospective analysis of 56 patients with advanced melanoma who had previously shown resistance to ICI therapy. In the Group A (who have previously shown resistance to anti-CTLA-4, n = 28), the objective response rate (ORR) was 42.9%, with a disease control rate (DCR) of 53%. In the Group B (previously shown resistance to anti-PD-1, n = 28), the ORR was 17.9%, and the DCR was 25%. The ORR was lower in two subgroups: patients who showed progression or relapse in the the initial radiological assessment of prior ICI therapy (ORR 10.5%) and patients who had previously received ICI in the adjuvant setting (ORR 8.3%). A Royal Marsden Hospital (RMH) score of 2-3 was a predictor of OS in both groups (Group A: HR 3.789, 95% CI 1.356-10.589, p = 0.011; Group B: HR 4.281, 95% CI 1.490-12.300, p = 0.007) and for PFS in the Group B (HR 3.167, 95% CI 1.062-9.442, p = 0.039). Anti-PD-1 therapy demonstrated efficacy following resistance to anti-CTLA-4, whereas combination ICI therapy showed lower response rates in patients resistant to anti-PD-1. Further studies are needed to confirm the RMH scores and other prognostic markers and to evaluate subgroups with lower efficacy of nivolumab-ipilimumab therapy.

Exploring resistance to immune checkpoint inhibitors and targeted therapies in melanoma

Melanoma is the most aggressive form of skin cancer, characterized by a poor prognosis, and its incidence has risen rapidly over the past 30 years. Recent therapies, notably immunotherapy and targeted therapy, have significantly improved the outcome of patients with metastatic melanoma. Previously dismal five-year survival rates of below 5% have shifted to over 50% of patients surviving the five-year mark, marking a significant shift in the landscape of melanoma treatment and survival. Unfortunately, about 50% of patients either do not respond to therapy or experience early or late relapses following an initial response. The underlying mechanisms for primary and secondary resistance to targeted therapies or immunotherapy and relapse patterns remain not fully identified. However, several molecular pathways and genetic factors have been associated with melanoma resistance to these treatments. Understanding these mechanisms paves the way for creating novel treatments that can address resistance and ultimately enhance patient outcomes in melanoma. This review explores the mechanisms behind immunotherapy and targeted therapy resistance in melanoma patients. Additionally, it describes the treatment strategies to overcome resistance, which have improved patients' outcomes in clinical trials and practice.

Targeting autophagy can synergize the efficacy of immune checkpoint inhibitors against therapeutic resistance: New promising strategy to reinvigorate cancer therapy

Immune checkpoints are a set of inhibitory and stimulatory molecules/mechanisms that affect the activity of immune cells to maintain the existing balance between pro- and anti-inflammatory signaling pathways and avoid the progression of autoimmune disorders. Tumor cells can employ these checkpoints to evade immune system. The discovery and development of immune checkpoint inhibitors (ICIs) was thereby a milestone in the area of immuno-oncology. ICIs stimulate anti-tumor immune responses primarily by disrupting co-inhibitory signaling mechanisms and accelerate immune-mediated killing of tumor cells. Despite the beneficial effects of ICIs, they sometimes encounter some degrees of therapeutic resistance, and thereby do not effectively act against tumors. Among multiple combination therapies have been introduced to date, targeting autophagy, as a cellular degradative process to remove expired organelles and subcellular constituents, has represented with potential capacities to overcome ICI-related therapy resistance. It has experimentally been illuminated that autophagy induction blocks the immune checkpoint molecules when administered in conjugation with ICIs, suggesting that autophagy activation may restrict therapeutic challenges that ICIs have encountered with. However, the autophagy flux can also provoke the immune escape of tumors, which must be considered. Since the conventional FDA-approved ICIs have designed and developed to target programmed cell death receptor/ligand 1 (PD-1/PD-L1) as well as cytotoxic T lymphocyte-associated molecule 4 (CTLA-4) immune checkpoint molecules, we aim to review the effects of autophagy targeting in combination with anti-PD-1/PD-L1- and anti-CTLA-4-based ICIs on cancer therapeutic resistance and tumor immune evasion.

Gut microbiome influences efficacy of Endostatin combined with PD-1 blockade against colorectal cancer

The combination of anti-angiogenic drugs and immune checkpoint inhibitors (ICIs) in the treatment of tumors is emerging as a way to improve ICIs-resistant tumor therapy. In addition, gut microbes (GMs) are involved in angiogenesis in the tumor microenvironment and are also associated with the antitumor function of immune checkpoint inhibitors. However, it is unclear whether gut microbes have a role in anti-tumor function in the combination of anti-angiogenic drugs and immune checkpoint inhibitors for cancer treatment. Endostatin, an angiogenesis inhibitor, has been widely used as an antiangiogenic therapy for cancer. We showed that combined therapy with an adenovirus encoding human endostatin, named Ad-E, and PD-1 blockade dramatically abrogated MC38 tumor growth. The structure of intestinal microbes in mice was changed after combination treatment. We found that the antitumor function of combination therapy was inhibited after the elimination of intestinal microbes. In mice with depleted microbiota, oral gavage of Bacteroides fragilis salvaged the antitumor effects of combination Ad-E and αPD-1 monoclonal antibody (mAb) to a certain extent. Further, Bacteroides fragilis could improve CD3+T cells, NK cells, and IFNγ+CD8+ T cells in the tumor microenvironment to inhibit tumor growth. Besides, Bacteroides fragilis might restore antitumor function by down-regulating isobutyric acid (IBA). Our results suggested that GMs may be involved in the combination of Ad-E and αPD-1 mAb for cancer treatment, which has oncological implications for tumor growth dynamics and cancer immune surveillance.

Molecular Susceptibility and Treatment Challenges in Melanoma

Melanoma is the most aggressive subtype of cancer, with a higher propensity to spread compared to most solid tumors. The application of OMICS approaches has revolutionized the field of melanoma research by providing comprehensive insights into the molecular alterations and biological processes underlying melanoma development and progression. This review aims to offer an overview of melanoma biology, covering its transition from primary to malignant melanoma, as well as the key genes and pathways involved in the initiation and progression of this disease. Utilizing online databases, we extensively explored the general expression profile of genes, identified the most frequently altered genes and gene mutations, and examined genetic alterations responsible for drug resistance. Additionally, we studied the mechanisms responsible for immune checkpoint inhibitor resistance in melanoma.

Stringent monitoring can decrease mortality of immune checkpoint inhibitor induced cardiotoxicity

Background

Immune checkpoint inhibitor (ICI)-induced myocarditis is a rare immune-related adverse event (irAE) with a fatality rate of 40%-46%. However, irMyocarditis can be asymptomatic. Thus, improved monitoring, detection and therapy are needed. This study aims to generate knowledge on pathogenesis and assess outcomes in cancer centers with intensified patient management.

Methods

Patients with cardiac irAEs from the SERIO registry (www.serio-registry.org) were analyzed for demographics, ICI-related information (type of ICI, therapy line, combination with other drugs, onset of irAE, and tumor response), examination results, irAE treatment and outcome, as well as oncological endpoints. Cardiac biopsies of irMyocarditis cases (n = 12) were analyzed by Nanostring and compared to healthy heart muscle (n = 5) and longitudinal blood sampling was performed for immunophenotyping of irMyocarditis-patients (n = 4 baseline and n = 8 during irAE) in comparison to patients without toxicity under ICI-therapy (n = 4 baseline and n = 7 during ICI-therapy) using flow cytometry.

Results

A total of 51 patients with 53 cardiac irAEs induced by 4 different ICIs (anti-PD1, anti-PD-L1, anti-CTLA4) were included from 12 centers in 3 countries. Altogether, 83.0% of cardiac irAEs were graded as severe or life-threatening, and 11.3% were fatal (6/53). Thus, in centers with established consequent troponin monitoring, work-up upon the rise in troponin and consequent treatment of irMyocarditis with corticosteroids and -if required-second-line therapy mortality rate is much lower than previously reported. The median time to irMyocarditis was 36 days (range 4-1,074 days) after ICI initiation, whereas other cardiotoxicities, e.g. asystolia or myocardiopathy, occurred much later. The cytokine-mediated signaling pathway was differentially regulated in myocardial biopsies as compared to healthy heart based on enrichment Gene Ontology analysis. Additionally, longitudinal peripheral blood mononuclear cell (PBMC) samples from irMyocarditis-patients indicated ICI-driven enhanced CD4+ Treg cells and reduced CD4+ T cells. Immunophenotypes, particularly effector memory T cells of irMyocarditis-patients differed from those of ICI-treated patients without side effects. LAG3 expression on T cells and PD-L1 expression on dendritic cells could serve as predictive indicators for the development of irMyocarditis.

Conclusion

Interestingly, our cohort shows a very low mortality rate of irMyocarditis-patients. Our data indicate so far unknown local and systemic immunological patterns in cardiotoxicity.

Tumor characteristics of dissociated response to immune checkpoint inhibition in advanced melanoma

INTRODUCTION

Immune checkpoint inhibition (ICI) has improved patients' outcomes in advanced melanoma, often resulting in durable response. However, not all patients have durable responses and the patients with dissociated response are a valuable subgroup to identify mechanisms of ICI resistance.

METHODS

Stage IV melanoma patients treated with ICI and dissociated response were retrospectively screened for available samples containing sufficient tumor at least at two time-points. Included were one patient with metachronous regressive and progressive lesions at the same site, two patients with regressive and novel lesion at different sites, and three patients with regressive and progressive lesions at different sites. In addition, four patients with acquired resistant tumor samples without a matched second sample were included.

RESULTS

In the majority of patients, the progressive tumor lesion contained higher CD8+ T cell counts/mm2 and interferon-gamma (IFNγ) signature level, but similar tumor PD-L1 expression. The tumor mutational burden levels were in 2 out 3 lesions higher compared to the corresponding regressive tumors lesion. In the acquired tumor lesions, high CD8+/mm2 and relatively high IFNγ signature levels were observed. In one patient in both the B2M and PTEN gene a stop gaining mutation and in another patient a pathogenic POLE mutation were found.

CONCLUSION

Intrapatient comparison of progressive versus regressive lesions indicates no defect in tumor T cell infiltration, and in general no tumor immune exclusion were observed.

Checkpoint inhibitors and anti-angiogenic agents: a winning combination

The combination of immune checkpoint inhibitors and anti-angiogenic agents is a promising new approach in cancer treatment. Immune checkpoint inhibitors block the signals that help cancer cells evade the immune system, while anti-angiogenic agents target the blood vessels that supply the tumour with nutrients and oxygen, limiting its growth. Importantly, this combination triggers synergistic effects based on molecular and cellular mechanisms, leading to better response rates and longer progression-free survival than treatment alone. However, these combinations can also lead to increased side effects and require close monitoring.

Molecular Classifiers in Skin Cancers: Challenges and Promises

Skin cancers are common and heterogenous malignancies affecting up to two in three Australians before age 70. Despite recent developments in diagnosis and therapeutic strategies, the mortality rate and costs associated with managing patients with skin cancers remain high. The lack of well-defined clinical and histopathological features makes their diagnosis and classification difficult in some cases and the prognostication difficult in most skin cancers. Recent advancements in large-scale "omics" studies, including genomics, transcriptomics, proteomics, metabolomics and imaging-omics, have provided invaluable information about the molecular and visual landscape of skin cancers. On many occasions, it has refined tumor classification and has improved prognostication and therapeutic stratification, leading to improved patient outcomes. Therefore, this paper reviews the recent advancements in omics approaches and appraises their limitations and potential for better classification and stratification of skin cancers.

Myeloid-Derived Suppressor Cells (MDSC) in Melanoma Patients Treated with Anti-PD-1 Immunotherapy

Myeloid-derived suppressor cells (MDSC) are a subset of immature myeloid cells with suppressive activity well described in the context of cancer. They inhibit anti-tumour immunity, promote metastasis formation and can lead to immune therapy resistance. In a retrospective study, blood probes of 46 advanced melanoma patients were analysed before the first administration of anti-PD-1 immunotherapy and in the third month of treatment for MDSC, immature monocytic (ImMC), monocytic MDSC (MoMDSC) and granulocytic MDSC (GrMDSC) by multi-channel flow cytometry. Cell frequencies were correlated with response to immunotherapy, progression-free survival (PFS) and lactate dehydrogenase (LDH) serum level. Responders to anti-PD-1 therapy had higher MoMDSC levels (4.1 ± 1.2%) compared to non-responders (3.0 ± 1.2%) (p = 0.0333) before the first administration of anti-PD-1. No significant changes in MDSCs frequencies were observed in the groups of patients before and in the third month of therapy. The cut-off values of MDSCs, MoMDSCs, GrMDSCs and ImMCs for favourable 2- and 3-year PFS were established. Elevated LDH level is a negative prognostic factor of response to the treatment and is related to an elevated ratio of GrMDSCs and ImMCs level compared to patients' LDH level below the cut-off. Our data may provide a new perspective for more careful consideration of MDSCs, and specially MoMDSCs, as a tool for monitoring the immune status of melanoma patients. Changes in MDSC levels may have a potential prognostic value, however a correlation with other parameters must be established.

A Clinical Outcome of the Anti-PD-1 Therapy of Melanoma in Polish Patients Is Mediated by Population-Specific Gut Microbiome Composition

The gut microbiota is considered a key player modulating the efficacy of immune checkpoint inhibitor therapy. The study investigated the association between the response to anti-PD-1 therapy and the baseline gut microbiome in a Polish cohort of melanoma patients, alongside selected agents modifying the microbiome. Sixty-four melanoma patients enrolled for the anti-PD-1 therapy, and ten healthy subjects were recruited. The response to the treatment was assessed according to the response evaluation criteria in solid tumors, and patients were classified as responders or non-responders. The association between selected extrinsic factors and response was investigated using questionnaire-based analysis and the metataxonomics of the microbiota. In the responders, the Bacteroidota to Firmicutes ratio was higher, and the richness was decreased. The abundance of Prevotella copri and Bacteroides uniformis was related to the response, whereas the non-responders’ gut microbiota was enriched with Faecalibacterium prausnitzii and Desulfovibrio intestinalis and some unclassified Firmicutes. Dietary patterns, including plant, dairy, and fat consumption as well as gastrointestinal tract functioning were significantly associated with the therapeutic effects of the therapy. The specific gut microbiota along with diet were found to be associated with the response to the therapy in the population of melanoma patients.

Melanoma Management: From Epidemiology to Treatment and Latest Advances

Melanoma is the deadliest skin cancer, whose morbidity and mortality indicators show an increasing trend worldwide. In addition to its great heterogeneity, melanoma has a high metastatic potential, resulting in very limited response to therapies currently available, which were restricted to surgery, radiotherapy and chemotherapy for many years. Advances in knowledge about the pathophysiological mechanisms of the disease have allowed the development of new therapeutic classes, such as immune checkpoint and small molecule kinase inhibitors. However, despite the incontestable progress in the quality of life and survival rates of the patients, effectiveness is still far from desired. Some adverse side effects and resistance mechanisms are the main barriers. Thus, the search for better options has resulted in many clinical trials that are now investigating new drugs and/or combinations. The low water solubility of drugs, low stability and rapid metabolism limit the clinical potential and therapeutic use of some compounds. Thus, the research of nanotechnology-based strategies is being explored as the basis for the broad application of different types of nanosystems in the treatment of melanoma. Future development focus on challenges understanding the mechanisms that make these nanosystems more effective.

Chidamide plus Tyrosine Kinase Inhibitor Remodel the Tumor Immune Microenvironment and Reduce Tumor Progression When Combined with Immune Checkpoint Inhibitor in Naïve and Anti-PD-1 Resistant CT26-Bearing Mice

Combined inhibition of vascular endothelial growth factor receptor (VEGFR) and the programmed cell death protein 1 (PD-1) pathways has shown efficacy in multiple cancers; however, the clinical outcomes show limited benefits and the unmet clinical needs still remain and require improvement in efficacy. Using murine colon carcinoma (CT26) allograft models, we examined the efficacy and elucidated novel tumor microenvironment (TME) remodeling mechanisms underlying the combination of chidamide (a benzamide-based class l histone deacetylase inhibitor; brand name in Taiwan, Kepida®) with VEGF receptor tyrosine kinase inhibitor (TKIs; cabozantinib/regorafenib, etc.) and immune checkpoint inhibitors (ICIs; anti-PD-1/anti-PD-L1/anti-CTLA-4 antibodies). The TME was assessed using flow cytometry and RNA-sequencing to determine the novel mechanisms and their correlation with therapeutic effects in mice with significant treatment response. Compared with ICI alone or cabozantinib/regorafenib + ICI, combination of chidamide + cabozantinib/regorafenib + ICI increased the tumor response and survival benefits. In particular, treatment of CT26-bearing mice with chidamide + regorafenib + anti-PD-1 antibody showed a better objective response rate (ORR) and overall survival (OS). Similar results were observed in anti-PD-1 treatment-resistant mice. After treatment with this optimal combination, in the TME, RNA-sequencing revealed that downregulated mRNAs were correlated with leukocyte migration, cell chemotaxis, and macrophage gene sets, and flow cytometry analysis showed that the cell numbers of myeloid-derived polymorphonuclear suppressor cells and tumor-associated macrophages were decreased. Accordingly, chidamide + regorafenib + anti-PD-1 antibody combination therapy could trigger a novel TME remodeling mechanism by attenuating immunosuppressive cells, and restoring T-cell activation to enhance ORR and OS. Our studies also showed that the addition of Chidamide to the regorafenib + anti-PD-1 Ab combination could induce a durable tumor-specific response by attenuating immune suppression in the TME. In addition, this result suggests that TME remodeling, mediated by epigenetic immunomodulator combined with TKI and ICI, would be more advantageous for achieving a high objective response rate, when compared to TKI plus ICI or ICI alone, and maintaining long-lasting antitumor activity.

The Texas Immuno-Oncology Biorepository, a statewide biospecimen collection and clinical informatics system to enable longitudinal tumor and immune profiling

A detailed understanding of the molecular and immunological changes that occur longitudinally across tumors exposed to immune checkpoint inhibitors is a significant knowledge gap in oncology. To address this unmet need, we created a statewide biospecimen collection and clinical informatics system to enable longitudinal tumor and immune profiling and to enhance translational research. The Texas Immuno-Oncology Biorepository (TIOB) consents patients to collect, process, store, and analyze serial biospecimens of tissue, blood, urine, and stool from a diverse population of over 100,000 cancer patients treated each year across the Baylor Scott & White Health system. Here we sought to demonstrate that these samples were fit for purpose with regard to downstream multi-omic assays. Plasma, urine, peripheral blood mononuclear cells, and stool samples from 11 enrolled patients were collected from various cancer types. RNA isolated from extracellular vesicles derived from plasma and urine was sufficient for transcriptomics. Peripheral blood mononuclear cells demonstrated excellent yield and viability. Ten of 11 stool samples produced RNA quality to enable microbiome characterization. Sample acquisition and processing methods are known to impact sample quality and performance. We demonstrate that consistent acquisition methodology, sample preparation, and sample storage employed by the TIOB can produce high-quality specimens, suited for employment in a wide array of multi-omic platforms, enabling comprehensive immune and molecular profiling.

Cannabidiol Interacts Antagonistically with Cisplatin and Additively with Mitoxantrone in Various Melanoma Cell Lines-An Isobolographic Analysis

The medical application of cannabidiol (CBD) has been gathering increasing attention in recent years. This non-psychotropic cannabis-derived compound possesses antiepileptic, antipsychotic, anti-inflammatory and anxiolytic properties. Recent studies report that it also exerts antineoplastic effects in multiple types of cancers, including melanoma. In this in vitro study we tried to reveal the anticancer properties of CBD in malignant melanoma cell lines (SK-MEL 28, A375, FM55P and FM55M2) administered alone, as well as in combination with mitoxantrone (MTX) or cisplatin (CDDP). The effects of CBD on the viability of melanoma cells were measured by the MTT assay; cytotoxicity was determined in the LDH test and proliferation in the BrdU test. Moreover, the safety of CBD was tested in human keratinocytes (HaCaT) in LDH and MTT tests. Results indicate that CBD reduces the viability and proliferation of melanoma-malignant cells and exerts additive interactions with MTX. Unfortunately, CBD produced antagonistic interaction when combined with CDDP. CBD does not cause significant cytotoxicity in HaCaT cell line. In conclusion, CBD may be considered as a part of melanoma multi-drug therapy when combined with MTX. A special attention should be paid to the combination of CBD with CDDP due to the antagonistic interaction observed in the studied malignant melanoma cell lines.

Targeting PARP1 to Enhance Anticancer Checkpoint Immunotherapy Response: Rationale and Clinical Implications

Reinvigorating the antitumor immune response using immune checkpoint inhibitors (ICIs) has revolutionized the treatment of several malignancies. However, extended use of ICIs has resulted in a cancer-specific response. In tumors considered to be less immunogenic, the response rates were low or null. To overcome resistance and improve the beneficial effects of ICIs, novel strategies focused on ICI-combined therapies have been tested. In particular, poly ADP-ribose polymerase inhibitors (PARPi) are a class of agents with potential for ICI combined therapy. PARPi impairs single-strand break DNA repair; this mechanism involves synthetic lethality in tumor cells with deficient homologous recombination. More recently, novel evidence indicated that PAPRi has the potential to modulate the antitumor immune response by activating antigen-presenting cells, infiltrating effector lymphocytes, and upregulating programmed death ligand-1 in tumors. This review covers the current advances in the immune effects of PARPi, explores the potential rationale for combined therapy with ICIs, and discusses ongoing clinical trials.

Immunomodulatory Properties of Immune Checkpoint Inhibitors-More than Boosting T-Cell Responses?

The approval of immune checkpoint inhibitors (ICI) that serve to enhance effector T-cell anti-tumor responses has strongly improved success rates in the treatment of metastatic melanoma and other tumor types. The currently approved ICI constitute monoclonal antibodies blocking cytotoxic T-lymphocyte-associated protein (CTLA)-4 and anti-programmed cell death (PD)-1. By this, the T-cell-inhibitory CTLA-4/CD80/86 and PD-1/PD-1L/2L signaling axes are inhibited. This leads to sustained effector T-cell activity and circumvents the immune evasion of tumor cells, which frequently upregulate PD-L1 expression and modulate immune checkpoint molecule expression on leukocytes. As a result, profound clinical responses are observed in 40-60% of metastatic melanoma patients. Despite the pivotal role of T effector cells for triggering anti-tumor immunity, mounting evidence indicates that ICI efficacy may also be attributable to other cell types than T effector cells. In particular, emerging research has shown that ICI also impacts innate immune cells, such as myeloid cells, natural killer cells and innate lymphoid cells, which may amplify tumoricidal functions beyond triggering T effector cells, and thus improves clinical efficacy. Effects of ICI on non-T cells may additionally explain, in part, the character and extent of adverse effects associated with treatment. Deeper knowledge of these effects is required to further develop ICI treatment in terms of responsiveness of patients to treatment, to overcome resistance to ICI and to alleviate adverse effects. In this review we give an overview into the currently known immunomodulatory effects of ICI treatment in immune cell types other than the T cell compartment.

Immune checkpoint inhibitors for the treatment of melanoma

INTRODUCTION

: Immune checkpoint inhibitor (ICI) based immunotherapy is dramatically changing the management of many types of cancers including melanoma. In this malignancy, ICIs have been shown to prolong disease and progression free survival as well as overall survival of a percentage of treated patients, becoming the cornerstone of melanoma treatment.

AREAS COVERED

: In this review, first, we will describe the mechanisms of immune checkpoint activation and inhibition, second, we will summarize the results obtained with ICIs in melanoma treatment in terms of efficacy as well as toxicity, third, we will discuss the potential mechanisms of immune escape from ICI, and lastly, we will review the potential predictive biomarkers of clinical efficacy of ICI-based immunotherapy in melanoma.

EXPERT OPINION

: ICIs represent one of the pillars of melanoma treatment. The success of ICI-based therapy is limited by the development of escape mechanisms which allow melanoma cells to avoid recognition and destruction by immune cells. These results emphasize the need of additional studies to confirm the efficacy of therapies which combine different classes of ICIs as well as ICIs with other types of therapies. Furthermore, novel and more effective predictive biomarkers are needed to better stratify melanoma patients in order to define more precisely the therapeutic algorithms.

Ultrasound-Responsive Nrf2-Targeting siRNA-Loaded Nanobubbles for Enhancing the Treatment of Melanoma

The siRNA-mediated inhibition of nuclear factor E2-related factor 2 (Nrf2) can be an attractive approach to overcome chemoresistance in various malignant tumors, including melanoma. This work aims at designing a new type of chitosan-shelled nanobubble for the delivery of siRNA against Nrf2 in combination with an ultrasound. A new preparation method based on a water-oil-water (W/O/W) double-emulsion was purposely developed for siRNA encapsulation in aqueous droplets within a nanobubble core. Stable, very small NB formulations were obtained, with sizes of about 100 nm and a positive surface charge. siRNA was efficiently loaded in NBs, reaching an encapsulation efficiency of about 90%. siNrf2-NBs downregulated the target gene in M14 cells, sensitizing the resistant melanoma cells to the cisplatin treatment. The combination with US favored NB cell uptake and transfection efficiency. Based on the results, nanobubbles have shown to be a promising US responsive tool for siRNA delivery, able to overcome chemoresistance in melanoma cancer cells.

The Anticancer Potential of Doxycycline and Minocycline-A Comparative Study on Amelanotic Melanoma Cell Lines

Malignant melanoma is still a serious medical problem. Relatively high mortality, a still-growing number of newly diagnosed cases, and insufficiently effective methods of therapy necessitate melanoma research. Tetracyclines are compounds with pleiotropic pharmacological properties. Previously published studies on melanotic melanoma cells ascertained that minocycline and doxycycline exerted an anti-melanoma effect. The purpose of the study was to assess the anti-melanoma potential and mechanisms of action of minocycline and doxycycline using A375 and C32 human amelanotic melanoma cell lines. The obtained results indicate that the tested drugs inhibited proliferation, decreased cell viability, and induced apoptosis in amelanotic melanoma cells. The treatment caused changes in the cell cycle profile and decreased the intracellular level of reduced thiols and mitochondrial membrane potential. The exposure of A375 and C32 cells to minocycline and doxycycline triggered the release of cytochrome c and activated initiator and effector caspases. The anti-melanoma effect of analyzed drugs appeared to be related to the up-regulation of ERK1/2 and MITF. Moreover, it was noticed that minocycline and doxycycline increased the level of LC3A/B, an autophagy marker, in A375 cells. In summary, the study showed the pleiotropic anti-cancer action of minocycline and doxycycline against amelanotic melanoma cells. Considering all results, it could be concluded that doxycycline was a more potent drug than minocycline.

In Vivo Melanoma Cell Morphology Reflects Molecular Signature and Tumor Aggressiveness

Melanoma is the deadliest type of skin cancer, characterized by high cellular heterogeneity which contributes to therapy resistance and unpredictable disease outcome. Recently, by correlating Reflectance-Confocal-Microscopy (RCM) morphology with histopathological type, we identified four distinct melanoma-subtypes: dendritic-cell (DC), round-cell (RC), dermal-nest (DN), and combined-type (CT) melanomas. In the present study, each RCM-melanoma subtype expressed a specific biomolecular profile and biological behavior in vitro. Markers of tumor aggressiveness, including Ki67, MERTK, nestin and stemness markers, were highest in the most invasive CT and DN melanomas, as compared to DC and RC. This was also confirmed in multicellular tumor spheroids. Transcriptomic analysis showed a modulation of cancer progression-associated genes from DC to CT melanomas. The switch from E- to N-cadherin expression proved the epithelial-to-mesenchymal transition from DC to CT subtypes. The DN melanoma was predominantly located in the dermis, as also shown in skin reconstructs. It displayed a unique behavior and a molecular profile associated with a high degree of aggressiveness. Altogether, our results demonstrate that each RCM-melanoma subtype has a distinct biological and gene expression profile, related to tumor aggressiveness, confirming that RCM can be a dependable tool for in vivo detecting different types of melanoma and for early diagnostic screening.

NK cell upraise in the dark world of cancer stem cells

One of the obstacles in treating different cancers, especially solid tumors, is cancer stem cells (CSCs) with their ability in resistance to chemo/radio therapy. The efforts for finding advanced treatments to overcome these cells have led to the emergence of advanced immune cell-based therapy (AICBT). Today, NK cells have become the center of attention since they have been proved to show an appropriate cytotoxicity against different cancer types as well as the capability of detecting and killing CSCs. Attempts for reaching an off-the-shelf source of NK cells have been made and resulted in the emergence of chimeric antigen receptor natural killer cells (CAR-NK cells). The CAR technology has then been used for generating more cytotoxic and efficient NK cells, which has increased the hope for cancer treatment. Since utilizing this advanced technology to target CSCs have been published in few studies, the present study has focused on discussing the characteristics of CSCs, which are detected and targeted by NK cells, the advantages and restrictions of using CAR-NK cells in CSCs treatment and the probable challenges in this process.