Multi-organ landscape of therapy-resistant melanoma

Targeting anticancer immunity in melanoma tumour microenvironment: unleashing the potential of adjuvants, drugs, and phytochemicals

Melanoma poses a challenge in oncology because of its aggressive nature and limited treatment modalities. The tumour microenvironment (TME) in melanoma contains unique properties such as an immunosuppressive and high-density environment, unusual vasculature, and a high number of stromal and immunosuppressive cells. In recent years, numerous experiments have focused on boosting the immune system to effectively remove malignant cells. Adjuvants, consisting of phytochemicals, toll-like receptor (TLR) agonists, and cytokines, have shown encouraging results in triggering antitumor immunity and augmenting the therapeutic effectiveness of anticancer therapy. These adjuvants can stimulate the maturation of dendritic cells (DCs) and infiltration of cytotoxic CD8+ T lymphocytes (CTLs). Furthermore, nanocarriers can help to deliver immunomodulators and antigens directly to the tumour stroma, thereby improving their efficacy against malignant cells. The remodelling of melanoma TME utilising phytochemicals, agonists, and other adjuvants can be combined with current modalities for improving therapy outcomes. This review article explores the potential of adjuvants, drugs, and their nanoformulations in enhancing the anticancer potency of macrophages, CTLs, and natural killer (NK) cells. Additionally, the capacity of these agents to repress the function of immunosuppressive components of melanoma TME, such as immunosuppressive subsets of macrophages, stromal and myeloid cells will be discussed.

The Fanconi anemia pathway induces chromothripsis and ecDNA-driven cancer drug resistance

Chromothripsis describes the catastrophic shattering of mis-segregated chromosomes trapped within micronuclei. Although micronuclei accumulate DNA double-strand breaks and replication defects throughout interphase, how chromosomes undergo shattering remains unresolved. Using CRISPR-Cas9 screens, we identify a non-canonical role of the Fanconi anemia (FA) pathway as a driver of chromothripsis. Inactivation of the FA pathway suppresses chromosome shattering during mitosis without impacting interphase-associated defects within micronuclei. Mono-ubiquitination of FANCI-FANCD2 by the FA core complex promotes its mitotic engagement with under-replicated micronuclear chromosomes. The structure-selective SLX4-XPF-ERCC1 endonuclease subsequently induces large-scale nucleolytic cleavage of persistent DNA replication intermediates, which stimulates POLD3-dependent mitotic DNA synthesis to prime shattered fragments for reassembly in the ensuing cell cycle. Notably, FA-pathway-induced chromothripsis generates complex genomic rearrangements and extrachromosomal DNA that confer acquired resistance to anti-cancer therapies. Our findings demonstrate how pathological activation of a central DNA repair mechanism paradoxically triggers cancer genome evolution through chromothripsis.

Leptomeningeal metastases from solid tumors: A Society for Neuro-Oncology and American Society of Clinical Oncology consensus review on clinical management and future directions

Leptomeningeal metastases (LM) are increasingly becoming recognized as a treatable, yet generally incurable, complication of advanced cancer. As modern cancer therapeutics have prolonged the lives of patients with metastatic cancer, specifically in patients with parenchymal brain metastases, treatment options, and clinical research protocols for patients with LM from solid tumors have similarly evolved to improve survival within specific populations. Recent expansions in clinical investigation, early diagnosis, and drug development have given rise to new unanswered questions. These include leptomeningeal metastasis biology and preferred animal modeling, epidemiology in the modern cancer population, ensuring validation and accessibility of newer leptomeningeal metastasis diagnostics, best clinical practices with multimodality treatment options, clinical trial design and standardization of response assessments, and avenues worthy of further research. An international group of multi-disciplinary experts in the research and management of LM, supported by the Society for Neuro-Oncology and American Society of Clinical Oncology, were assembled to reach a consensus opinion on these pressing topics and provide a roadmap for future directions. Our hope is that these recommendations will accelerate collaboration and progress in the field of LM and serve as a platform for further discussion and patient advocacy.

Interferon signaling and ferroptosis in tumor immunology and therapy

This study sought to elucidate the mechanisms underlying the impact of the interferon signaling pathway on Ferroptosis in tumor cells and its correlation with CD8 + T cell exhaustion. Using mouse models and single-cell sequencing, the researchers studied the interaction between CD8 + T cells and the interferon signaling pathway. Differential gene analysis revealed key genes involved in CD8 + T cell exhaustion, and their downstream factors were explored using bioinformatics tools. The expression levels of interferon-related genes associated with Ferroptosis were analyzed using data from the TCGA database, and their relevance to tumor tissue Ferroptosis and patients' prognosis was determined. In vitro experiments were conducted to measure the levels of IFN-γ, MDA, and LPO, as well as tumor cell viability and apoptosis. In vivo validation using a mouse tumor model confirmed the results obtained from the in vitro experiments, highlighting the potential of silencing HSPA6 or DNAJB1 in enhancing the efficacy of PD-1 therapy and inhibiting tumor growth and migration.

ALDH1A3-acetaldehyde metabolism potentiates transcriptional heterogeneity in melanoma

Cancer cellular heterogeneity and therapy resistance arise substantially from metabolic and transcriptional adaptations, but how these are interconnected is poorly understood. Here, we show that, in melanoma, the cancer stem cell marker aldehyde dehydrogenase 1A3 (ALDH1A3) forms an enzymatic partnership with acetyl-coenzyme A (CoA) synthetase 2 (ACSS2) in the nucleus to couple high glucose metabolic flux with acetyl-histone H3 modification of neural crest (NC) lineage and glucose metabolism genes. Importantly, we show that acetaldehyde is a metabolite source for acetyl-histone H3 modification in an ALDH1A3-dependent manner, providing a physiologic function for this highly volatile and toxic metabolite. In a zebrafish melanoma residual disease model, an ALDH1-high subpopulation emerges following BRAF inhibitor treatment, and targeting these with an ALDH1 suicide inhibitor, nifuroxazide, delays or prevents BRAF inhibitor drug-resistant relapse. Our work reveals that the ALDH1A3-ACSS2 couple directly coordinates nuclear acetaldehyde-acetyl-CoA metabolism with specific chromatin-based gene regulation and represents a potential therapeutic vulnerability in melanoma.

Evodiamine encapsulated by hyaluronic acid modified zeolitic imidazolate framework-8 for tumor targeted therapy

Evodiamine (EVO), a natural bioactive compound extracted from Evodia rutaecarpa, shows therapeutic ability against malignant melanoma. However, the poor solubility and bioavailability of EVO limit its clinical application. Metal-organic frameworks (MOFs) have shown excellent physical and chemical properties and are widely used as drug delivery systems. Among them, zeolitic imidazolate framework-8 (ZIF-8) is a research popular material because of its unique properties, such as hydrothermal stability, non-toxicity, biocompatibility, and pH sensitivity. In this study, in order to load EVO, a drug carrier that hyaluronic acid (HA) modified zeolitic imidazolate framework-8 (ZIF-8) is synthesized. This drug carrier has shown drug loading with 6.2 ± 0.6%, and the nano drugs (EVO@ZIF-8/HA) have good dispersibility. Owing to the decoration HA of EVO@ZIF-8, the potential of the nano drugs is reversed from the positive charge to the negative charge, which is beneficial to blood circulation in vivo. Furthermore, because the CD44-expressing in tumor cells is excessed, the endocytosis and accumulation of nano drugs in tumor cells are beneficial to improvement. Compared with free EVO, EVO@ZIF-8/HA has shown a significantly improved anti-tumor efficacy in vitro and in vivo. In summary, the drug carrier effectively addresses the challenges that are caused by the strong hydrophobicity and low bioavailability of EVO, thereby targeted tumor therapy of EVO can be achieved.

RNAi-based drug design: considerations and future directions

More than 25 years after its discovery, the post-transcriptional gene regulation mechanism termed RNAi is now transforming pharmaceutical development, proved by the recent FDA approval of multiple small interfering RNA (siRNA) drugs that target the liver. Synthetic siRNAs that trigger RNAi have the potential to specifically silence virtually any therapeutic target with unprecedented potency and durability. Bringing this innovative class of medicines to patients, however, has been riddled with substantial challenges, with delivery issues at the forefront. Several classes of siRNA drug are under clinical evaluation, but their utility in treating extrahepatic diseases remains limited, demanding continued innovation. In this Review, we discuss principal considerations and future directions in the design of therapeutic siRNAs, with a particular emphasis on chemistry, the application of informatics, delivery strategies and the importance of careful target selection, which together influence therapeutic success.

Genomic deletions explain the generation of alternative BRAF isoforms conferring resistance to MAPK inhibitors in melanoma

Resistance to MAPK inhibitors (MAPKi), the main cause of relapse in BRAF-mutant melanoma, is associated with the production of alternative BRAF mRNA isoforms (altBRAFs) in up to 30% of patients receiving BRAF inhibitor monotherapy. These altBRAFs have been described as being generated by alternative pre-mRNA splicing, and splicing modulation has been proposed as a therapeutic strategy to overcome resistance. In contrast, we report that altBRAFs are generated through genomic deletions. Using different in vitro models of altBRAF-mediated melanoma resistance, we demonstrate the production of altBRAFs exclusively from the BRAF V600E allele, correlating with corresponding genomic deletions. Genomic deletions are also detected in tumor samples from melanoma and breast cancer patients expressing altBRAFs. Along with the identification of altBRAFs in BRAF wild-type and in MAPKi-naive melanoma samples, our results represent a major shift in our understanding of mechanisms leading to the generation of BRAF transcripts variants associated with resistance in melanoma.

Investigational Approaches for Treatment of Melanoma Patients Progressing After Standard of Care

ABSTRACT

The advent of effective immunotherapy, specifically cytotoxic T-lymphocyte associated protein 4 and programmed cell death 1 inhibitors, as well as targeted therapy including BRAF/MEK inhibitors, has dramatically changed the prognosis for metastatic melanoma patients. Up to 50% of patients may experience long-term survival currently. Despite these advances in melanoma treatment, many patients still progress and die of their disease. As such, there are many studies aimed at providing new treatment options for this population. Therapies currently under investigation include, but are not limited to, novel immunotherapies, targeted therapies, tumor-infiltrating lymphocytes and other cellular therapies, oncolytic viral therapy and other injectables, and fecal microbiota transplant. In this review, we discuss the emerging treatment options for metastatic melanoma patients who have progressed on standard of care treatments.

Targeting of M2 macrophages with IL-13-functionalized liposomal prednisolone inhibits melanoma angiogenesis in vivo

The intricate cooperation between cancer cells and nontumor stromal cells within melanoma microenvironment (MME) enables tumor progression and metastasis. We previously demonstrated that the interplay between tumor-associated macrophages (TAMs) and melanoma cells can be disrupted by using long-circulating liposomes (LCLs) encapsulating prednisolone phosphate (PLP) (LCL-PLP) that inhibited tumor angiogenesis coordinated by TAMs. In this study, our goal was to improve LCL specificity for protumor macrophages (M2-like (i.e., TAMs) macrophages) and to induce a more precise accumulation at tumor site by loading PLP into IL-13-conjugated liposomes (IL-13-LCL-PLP), since IL-13 receptor is overexpressed in this type of macrophages. The IL-13-LCL-PLP liposomal formulation was obtained by covalent attachment of thiolated IL-13 to maleimide-functionalized LCL-PLP. C57BL/6 mice bearing B16.F10 s.c melanoma tumors were used to investigate the antitumor action of LCL-PLP and IL-13-LCL-PLP. Our results showed that IL-13-LCL-PLP formulation remained stable in biological fluids after 24h and it was preferentially taken up by M2 polarized macrophages. IL-13-LCL-PLP induced strong tumor growth inhibition compared to nonfunctionalized LCL-PLP at the same dose, by altering TAMs-mediated angiogenesis and oxidative stress, limiting resistance to apoptosis and invasive features in MME. These findings suggest IL-13-LCL-PLP might become a promising delivery platform for chemotherapeutic agents in melanoma.

Functional analysis of recurrent CDC20 promoter variants in human melanoma

Small nucleotide variants in non-coding regions of the genome can alter transcriptional regulation, leading to changes in gene expression which can activate oncogenic gene regulatory networks. Melanoma is heavily burdened by non-coding variants, representing over 99% of total genetic variation, including the well-characterized TERT promoter mutation. However, the compendium of regulatory non-coding variants is likely still functionally under-characterized. We developed a pipeline to identify hotspots, i.e. recurrently mutated regions, in melanoma containing putatively functional non-coding somatic variants that are located within predicted melanoma-specific regulatory regions. We identified hundreds of statistically significant hotspots, including the hotspot containing the TERT promoter variants, and focused on a hotspot in the promoter of CDC20. We found that variants in the promoter of CDC20, which putatively disrupt an ETS motif, lead to lower transcriptional activity in reporter assays. Using CRISPR/Cas9, we generated an indel in the CDC20 promoter in human A375 melanoma cell lines and observed decreased expression of CDC20, changes in migration capabilities, increased growth of xenografts, and an altered transcriptional state previously associated with a more proliferative and less migratory state. Overall, our analysis prioritized several recurrent functional non-coding variants that, through downregulation of CDC20, led to perturbation of key melanoma phenotypes.

An injectable, in situ forming and NIR-responsive hydrogel persistently reshaping tumor microenvironment for efficient melanoma therapy

BACKGROUND

Melanoma is a highly aggressive form of skin cancer with increasing incidence and mortality rates. Chemotherapy, the primary treatment for melanoma, is limited by hypoxia-induced drug resistance and suppressed immune response at the tumor site. Modulating the tumor microenvironment (TME) to alleviate hypoxia and enhance immune response has shown promise in improving chemotherapy outcomes.

METHODS

In this study, a novel injectable and in situ forming hydrogel named MD@SA was developed using manganese dioxide (MnO2) nanosheets pre-loaded with the chemotherapy drug doxorubicin (DOX) and mixed with sodium alginate (SA). The sustainable drug delivery, oxygen generation ability, and photothermal property of MD@SA hydrogel were characterized. The therapeutic efficacy of hydrogel was studied in B16F10 in vitro and B16F10 tumor-bearing mice in vivo. The immune effects on macrophages were analyzed by flow cytometry, real-time quantitative reverse transcription PCR, and immunofluorescence analyses.

RESULTS

The MD@SA hydrogel catalyzed the tumoral hydrogen peroxide (H2O2) into oxygen, reducing the hypoxic TME, down-regulating hypoxia-inducible factor-1 alpha (HIF-1α) and drug efflux pump P-glycoprotein (P-gp). The improved TME conditions enhanced the uptake of DOX by melanoma cells, enhancing its efficacy and facilitating the release of tumor antigens. Upon NIR irradiation, the photothermal effect of the hydrogel induced tumor apoptosis to expose more tumor antigens, thus re-educating the M2 type macrophage into the M1 phenotype. Consequently, the MD@SA hydrogel proposes an ability to constantly reverse the hypoxic and immune-inhibited TME, which eventually restrains cancer proliferation.

CONCLUSION

The injectable and in situ forming MD@SA hydrogel represents a promising strategy for reshaping the TME in melanoma treatment. By elevating oxygen levels and activating the immune response, this hydrogel offers a synergistic approach for TME regulation nanomedicine.

Site matters in metastatic melanoma

Metastasis and cross-therapy resistance to mitogen-activated protein kinase (MAPK) inhibition and immune checkpoint blockade (ICB) are significant clinical issues in melanoma. A new study in NatureMedicine by Liu et al. utilizes metastatic melanoma (MM) tumors from a rapid autopsy cohort to dissect genomic and transcriptomic features of therapy resistance, organ-specific gene signatures, and crosstalk between MM and organ sites.