Regression Of Melanoma Research Articles

Pericyte phenotype switching alleviates immunosuppression and sensitizes vascularized tumors to immunotherapy in preclinical models.

T cell-based immunotherapies are a promising therapeutic approach for multiple malignancies, but their efficacy is limited by tumor hypoxia arising from dysfunctional blood vessels. Here, we report that cell-intrinsic properties of a single vascular component, namely the pericyte, contribute to the control of tumor oxygenation, macrophage polarization, vessel inflammation, and T cell infiltration. Switching pericyte phenotype from a synthetic to a differentiated state reverses immune suppression and sensitizes tumors to adoptive T cell therapy, leading to regression of melanoma in mice. In melanoma patients, improved survival is correlated with enhanced pericyte maturity. Importantly, pericyte plasticity is regulated by signaling pathways converging on Rho kinase activity, with pericyte maturity being inducible by selective low-dose therapeutics that suppress pericyte MEK, AKT, or notch signaling. We also show that low-dose targeted anticancer therapy can durably change the tumor microenvironment without inducing adaptive resistance, creating a highly translatable pathway for redosing anticancer targeted therapies in combination with immunotherapy to improve outcome.

Recombinant ferritin-based nanoparticles as neoantigen carriers significantly inhibit tumor growth and metastasis

BackgroundTumor neoantigen peptide-based vaccines, systemic immunotherapies that enhance antitumor immunity by activating and expanding antigen-specific T cells, have achieved remarkable results in the treatment of a variety of solid tumors. However, how to effectively deliver neoantigens to induce robust antitumor immune responses remains a major obstacle.ResultsHere, we developed a safe and effective neoantigen peptide delivery system (neoantigen-ferritin nanoparticles, neoantigen-FNs) that successfully achieved effective lymph node targeting and induced robust antitumor immune responses. The genetically engineered self-assembled particles neoantigen-FNs with a size of 12 nm were obtained by fusing a neoantigen with optimized ferritin, which rapidly drainage to and continuously accumulate in lymph nodes. The neoantigen-FNs vaccine induced a greater quantity and quality of antigen-specific CD8+ T cells and resulted in significant growth control of multiple tumors, dramatic inhibition of melanoma metastasis and regression of established tumors. In addition, no obvious toxic side effects were detected in the various models, indicating the high safety of optimized ferritin as a vaccine carrier.ConclusionsHomogeneous and safe neoantigen-FNs could be a very promising system for neoantigen peptide delivery because of their ability to efficiently drainage to lymph nodes and induce efficient antitumor immune responses.Graphical

IL-12 and PD-1 peptide combination gene therapy for the treatment of melanoma

Interleukin-12 (IL-12) gene electrotransfer (GET) delivery is highly effective in inducing long-term, complete regression in mouse and human melanoma and other solid tumors. Therapeutic efficacy is enhanced by immune checkpoint inhibitors, and the combination of IL-12 plasmid GET (pIL-12 GET) and anti-programmed cell death protein 1 (PD-1) monoclonal antibodies has reached clinical trials. In this study, we designed peptides and plasmids encoding the mouse homologs of the pembrolizumab and nivolumab programmed cell death 1 ligand 1 (PD-L1) binding regions. We hypothesized that intratumor autocrine/paracrine peptide expression would block PD-1/PD-L1 binding and provide cancer patients with an effective and cost-efficient treatment alternative. We demonstrated that the mouse homolog to pembrolizumab was effective at blocking PD-1/PD-L1 invitro. After intratumor plasmid delivery, both peptides bound PD-L1 on tumor cells. We established that plasmid DNA delivery to tumors invivo or to tumor cells invitro upregulated several immune modulators and PD-L1 mRNA and protein, potentiating this therapy. Finally, we tested the combination of pIL-12 GET therapy and peptide plasmids. We determined that pIL-12 GET therapeutic efficacy could be enhanced by combination with the plasmid encoding the pembrolizumab mouse homolog.

Tumor-Localized Interleukin-2 and Interleukin-12 Combine with Radiation Therapy to Safely Potentiate Regression of Advanced Malignant Melanoma in Pet Dogs.

Cytokines IL2 and IL12 exhibit potent anticancer activity but suffer a narrow therapeutic window due to off-tumor immune cell activation. Engineering cytokines with the ability to bind and associate with tumor collagen after intratumoral injection potentiated response without toxicity in mice and was previously safe in pet dogs with sarcoma. Here, we sought to test the efficacy of this approach in dogs with advanced melanoma. This study examined 15 client-owned dogs with histologically or cytologically confirmed malignant melanoma that received a single 9-Gy fraction of radiotherapy, followed by six cycles of combined collagen-anchored IL2 and IL12 therapy every 2 weeks. Cytokine dosing followed a 3 + 3 dose escalation design, with the initial cytokine dose chosen from prior evaluation in canine sarcomas. No exclusion criteria for tumor stage or metastatic burden, age, weight, or neuter status were applied for this trial. Median survival regardless of the tumor stage or dose level was 256 days, and 10/13 (76.9%) dogs that completed treatment had CT-measured tumor regression at the treated lesion. In dogs with metastatic disease, 8/13 (61.5%) had partial responses across their combined lesions, which is evidence of locoregional response. Profiling by NanoString of treatment-resistant dogs revealed that B2m loss was predictive of poor response to this therapy. Collectively, these results confirm the ability of locally administered tumor-anchored cytokines to potentiate responses at regional disease sites when combined with radiation. This evidence supports the clinical translation of this approach and highlights the utility of comparative investigation in canine cancers.

Tumor eradication by triplet therapy with BRAF inhibitor, TLR 7 agonist, and PD-1 antibody for BRAF-mutated melanoma.

Programmed death 1 (PD-1)/programmed death-ligand 1 inhibitors are commonly used to treat various cancers, including melanoma. However, their efficacy as monotherapy is limited, and combination immunotherapies are being explored to improve outcomes. In this study, we investigated a combination immunotherapy involving an anti-PD-1 antibody that blocks the major adaptive immune-resistant mechanisms, a BRAF inhibitor that inhibits melanoma cell proliferation, and multiple primary immune-resistant mechanisms, such as cancer cell-derived immunosuppressive cytokines, and a Toll-like receptor 7 agonist that enhances innate immune responses that promote antitumor T-cell induction and functions. Using a xenogeneic nude mouse model implanted with human BRAF-mutated melanoma, a BRAF inhibitor vemurafenib was found to restore T-cell-stimulatory activity in conventional dendritic cells by reducing immunosuppressive cytokines, including interleukin 6, produced by human melanoma. Additionally, intravenous administration of the Toll-like receptor 7 agonist DSR6434 enhanced tumor growth inhibition by vemurafenib through stimulating the plasmacytoid dendritic cells/interferon-α/natural killer cell pathways and augmenting the T-cell-stimulatory activity of conventional dendritic cells. In a syngeneic mouse model implanted with murine BRAF-mutated melanoma, the vemurafenib and DSR6434 combination synergistically augmented the induction of melanoma antigen gp100-specific T cells and inhibited tumor growth. Notably, only triplet therapy with vemurafenib, DSR6434, and the anti-PD-1 antibody resulted in complete regression of SIY antigen-transduced BRAF-mutated melanoma in a CD8 T-cell-dependent manner. These findings indicate that a triple-combination strategy targeting adaptive and primary resistant mechanisms while enhancing innate immune responses that promote tumor-specific T cells may be crucial for effective tumor eradication.

Receptor tyrosine kinase inhibition leads to regression of acral melanoma by targeting the tumor microenvironment.

Acral melanoma (AM) is an aggressive melanoma variant that arises from palmar, plantar, and nail unit melanocytes. Compared to non-acral cutaneous melanoma (CM), AM is biologically distinct, has an equal incidence across genetic ancestries, typically presents in advanced stage disease, is less responsive to therapy, and has an overall worse prognosis. Independent analysis of published genomic and transcriptomic sequencing identified that receptor tyrosine kinase (RTK) ligands and adapter proteins are frequently amplified, translocated, and/or overexpressed in AM. To target these unique genetic changes, a zebrafish acral melanoma model was exposed to a panel of narrow and broad spectrum multi-RTK inhibitors, revealing that dual FGFR/VEGFR inhibitors decrease acral-analogous melanocyte proliferation and migration. The potent pan-FGFR/VEGFR inhibitor, Lenvatinib, uniformly induces tumor regression in AM patient-derived xenograft (PDX) tumors but only slows tumor growth in CM models. Unlike other multi-RTK inhibitors, Lenvatinib is not directly cytotoxic to dissociated AM PDX tumor cells and instead disrupts tumor architecture and vascular networks. Considering the great difficulty in establishing AM cell culture lines, these findings suggest that AM may be more sensitive to microenvironment perturbations than CM. In conclusion, dual FGFR/VEGFR inhibition may be a viable therapeutic strategy that targets the unique biology of AM.

Competing‐risks model for predicting the prognosis of patients with regressive melanoma based on the SEER database

AbstractBackgroundThe relationship between the regression and prognosis of melanoma has been debated for years. When competing‐risk events are present, using traditional survival analysis methods may induce bias in the identified prognostic factors that affect patients with regressive melanoma.MethodsData on patients diagnosed with regressive melanoma were extracted from the Surveillance, Epidemiology, and End Results (SEER) database during 2000–2019. Cumulative incidence function and Gray's test were used for the univariate analysis, and the Cox proportional‐hazards model and the Fine–Gray model were used for the multivariate analysis.ResultsA total of 1442 eligible patients were diagnosed with regressive melanoma, including 529 patients who died: 109 from regressive melanoma and 420 from other causes. The multivariate analysis using the Fine–Gray model revealed that SEER stage, surgery status, and marital status were important factors that affected the prognosis of regressive melanoma. Due to the existence of competing‐risk events, the Cox model may have induced biases in estimating the effect values, and the competing‐risks model was more advantageous in the analysis of multiple‐endpoint clinical survival data.ConclusionThe findings of this study may help clinicians to better understand regressive melanoma and provide reference data for clinical decisions.

Abstract 3918: Targeting MARCO in combination with anti-CTLA4 leads to enhanced melanoma regression and immune cell infiltration via macrophage reprogramming

Abstract Tumor-associated macrophages (TAM) are known to suppress responses to conventional therapeutics and the presence of TAM is generally related to poor prognosis in various cancers. Therefore, depletion of TAM has been one of the main strategies to break the ceiling of efficacy in cancer treatment. However, to date, TAM depletion strategies have not been successful in clinical trials1. Here, we introduce an approach to target TAM by employing Macrophage Receptor with Collagenous Structure (MARCO), a class A scavenger receptor, as a novel immune checkpoint. Previously, we showed MARCO to be the most upregulated mRNA in murine and human dendritic cells following their uptake of dead tumor cells (TP-DC)2. We also showed ex vivo treatment of TP-DC with anti-MARCO mAb (ED31) led to enhanced anti-tumor responses in vivo3,4. The aim of this current study was to explore whether targeting MARCO using ED31 could improve the efficacy of an immune checkpoint inhibitor in murine models of melanoma. In C57BL/6 mice with B16F10 tumors, adding ED31 to anti-CTLA4 mAb (αCTLA4) resulted in enhanced tumor regression and longer survival (p=0.001, p<0.05 vs αCTLA4 monotherapy; p<0.05, p<0.01 vs ED31 monotherapy, respectively). To explore the immune mechanism of ED31 with αCTLA4, we focused on the tumor microenvironment (TME) by flow cytometry. TME immune-profiling consistently revealed that one time treatment with this combination resulted in a rapid increase in the number of tumor infiltrating lymphocytes (TIL) including CD8+T (2.8-fold) and CD4+T cells (2.9-fold), NK cells (2.5-fold), activated CD11c+DC (2.2-fold) and F4/80+Mφ (2.5-fold), compared to αCTLA4 monotherapy (all with p<0.0001; vs αCTLA4 monotherapy, vs ED31 monotherapy, vs control, respectively). As measured by chemokine production using murine bone marrow-derived, in vitro M-CSF induced Mφ phenotypes (M1: polarized by IFNγ and LPS, M2: polarized by IL4, TAM-like Mφ: polarized by a supernatant from B16F10 cell line culture), ED31 exposure switched the pattern of chemokine productions from M2 and TAM-like Mφ into an M1 pattern. In vivo depletion of each immune cell type had a diminishing effect on the treatment efficacy (p<0.001 for CD8 depletion, p=0.01 for CD4 depletion, p<0.01 for NK1.1 depletion). However, Mφ depletion had a more profound impact by completely abrogating the anti-tumor efficacy and the associated survival benefit, in addition to completely reversing the increase in TIL infiltration and canceling the increase of M1 chemokines in vivo (all with p<0.05 vs Mφ depletion). These preclinical data support the proof-of-concept that a combination strategy of targeting MARCO along with αCTLA4 can lead to enhanced anti-tumor responses through utilizing TAMs rather than their depletion. 1 Immunity 2023;56:2188. 2 J Immunol 2003;171:2879. 3 Cancer Immunol Immunother 2010;59:875. 4 PLoS One 2013;8:e67795. Citation Format: Hidenori Takahashi, Patricio Perez-Villarroel, Rana Falahat, James J. Mulé. Targeting MARCO in combination with anti-CTLA4 leads to enhanced melanoma regression and immune cell infiltration via macrophage reprogramming [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3918.

Regression of metastatic malignant melanoma with dupilumab: A case report

AbstractExcoriated pruritus can be an intolerable symptom in patients with cancer where Type 2 inflammation and its associated cytokines IL‐4 and IL‐13 play major roles in the pruritus. Dupilumab, an antibody blocking IL‐4 and IL‐13, is approved for treating moderate to severe atopic dermatitis (AD) where itching is a significant symptom. We present a case report of intractable malignancy‐associated AD and pruritus with eosinophilia in a patient with stage IV malignant melanoma who was treated with dupilumab. Biweekly treatment with dupilumab led to an immediate improvement in itching and resolution of the AD, which subsided after a few doses and without significant adverse effects. Routine radiologic monitoring of the malignant melanoma showed concomitant resolution of secondary nodules in the lung, liver, and pleura. It was concluded that dupilumab may be a safe and effective treatment for intractable malignancy‐associated AD with pruritus and may have potential for moderating metastatic malignant melanoma.

Сlinical case of visceral metastasis of cutaneous melanoma

Cutaneous melanoma is the most common tumor that metastasizes to the gastrointestinal tract, however, the diagnosis of visceral metastases remains difficult due to its low symptoms. Lifetime verification of melanoma metastases in the digestive tract is only 1–4%. Additional difficulties in verifying visceral melanoma metastases arise due to spontaneous regression of the primary tumor. The presented rare clinical case illustrates a variant of the course of disseminated melanoma of the skin with metastatic lesions of the gastrointestinal tract, while the dissemination was preceded by spontaneous regression of melanoma of the skin. Despite the lifetime endoscopic verification of multiple visceral metastases of cutaneous myeloma, the patient’s prognosis is unfavorable. The fact of spontaneous regression of cutaneous melanoma influenced the late diagnosis of melanoma dissemination, also due to the rarity of melanoma metastasis in the mucosa of the upper digestive tract, endoscopists are not sufficiently aware of endoscopic variants of melanoma metastases. It should be noted that endoscopic diagnostic methods must necessarily be included in the examination plan of a patient with melanoma, and when dynamically monitoring patients with melanoma after treatment, it is necessary to pay attention to non-specific signs of gastrointestinal tract damage (abdominal pain, anemia). In addition, in a patient with a history of melanoma, with endoscopic detection of an unpigmented neoplasm, it should be differentiated with a possible metastatic lesion, histological and immunohistochemical examination of the biopsy should be performed.

Independent association of sex, age and the melanoma subtype with histological regression in invasive melanomas: A retrospective study

BackgroundHistological regression represents an immunologic host response and has been associated with better prognosis in cutaneous melanoma. ObjectiveTo investigate the independent association of clinicopathological features associated with histological regression in the subgroups of localized (stage I/II) and stage III invasive melanomas. MethodsThis was a retrospective study of Greek patients in the European Association of Dermato-Oncology (EADO) database, with invasive melanomas of the nodular melanoma (NM) or superficial spreading melanoma (SSM) subtype. ResultsIn a total of 561 cases, histological regression was present in 160 (28.5%). The median age of patients was 53 years old and 47.6% were males. Most melanomas were stage I and II (87.2%) and 59% were thin (Breslow ≤1 mm). There were 78.6% SSM and 21.4% NM. In multivariate logistic regression analysis, in the subgroup of stage I and II melanomas, age older than 50 years (OR: 1.67 95% CI: 1.09–2.55) and male sex (OR: 1.92, 95% CI: 1.26–2.92) were independent predictors associated with the presence of regression. In addition, the nodular subtype (versus SSM) was an independent factor less likely associated with the presence of regression (OR: 0.49, 95% CI: 0.25–0.96). Breslow thickness > 1.0 mm (OR: 1.16, 95% CI: 0.71–1.88) and localization were not significantly associated with regression. In stage III melanomas, older age was significantly associated with the presence of regression, while the nodular subtype was less likely to be independently associated with presence of regression. ConclusionsIn our study, male sex, age and nodular subtype were independently associated with histological regression. These results suggest possible sex- and subtype-related differences in the immunological responses in melanomas, warranting further studies.

Histopathologic regression in patients with primary cutaneous melanoma undergoing sentinel lymph node biopsy is associated with favorable survival and, after metastasis, with improved progression-free survival on immune checkpoint inhibitor therapy: A single-institutional cohort study

Histopathologic regression of cutaneous melanoma is considered a favorable prognostic factor, but its significance in clinical practice remains controversial. To investigate the prognostic importance of regression in patients with primary cutaneous melanoma undergoing sentinel lymph node (SLN) biopsy and to assess its significance in patients progressing to an unresectable stage requiring systemic therapy. We retrospectively reviewed patients with newly diagnosed melanoma undergoing SLN biopsy between 2010 and 2015 and available information on histopathologic regression (n=1179). Survival data and associations of clinical variables with SLN status were assessed. Patients with regressive melanoma showed favorable relapse-free (hazard ratio [HR], 0.52; P=.00013), distant metastasis-free (HR, 0.56; P=.0020), and melanoma-specific survival (HR, 0.35; P=.00053). Regression was associated with negative SLN (odds ratio, 0.48; P=.0077). In patients who progressed to an unresectable stage, regression was associated with favorable progression-free survival under immune checkpoint inhibition (HR, 0.43; P=.031) but not under targeted therapy (HR, 1.14; P=.73) or chemotherapy (HR, 3.65; P=.0095). Retrospective, single-institutional design. Regression of cutaneous melanoma is associated with improved prognosis in patients eligible for SLN biopsy as well as in patients with unresectable disease receiving systemic therapy with immune checkpoint inhibitors.

Mannose-functionalization of reconstituted high-density lipoprotein nanoparticles improves payload delivery and enhances M2-to-M1 phenotype reprogramming of RAW 264.7 macrophages polarized by B16-F10 melanoma cells

The targeting and conversion of the immunosuppressive (M2) tumor-associated macrophages (TAMs) to an immunostimulatory (M1) phenotype can induce tumor regression in advanced melanoma. We have previously characterized and reported the ability of reconstituted high-density lipoprotein nanoparticles (rHDL NPs) functionalized with DSPE-PEG-mannose (DPM) to deliver payload to macrophages. Herein, we investigate the modulation of macrophage phenotype and payload delivery mechanisms of the rHDL-DPM NPs in RAW 264.7 murine macrophages exposed to the conditioned medium (CM) from murine B16-F10 melanoma cells. The rHDL-DPM NPs loaded with the Stimulator of Interferon genes agonist, DMXAA, reduced protein levels of M2 markers. Through the mannose moiety, the rHDL-DPM-DMXAA NPs enhanced the production of interferon β and CXCL10 compared to the free DMXAA in the B16-F10 CM-educated RAW 264.7 macrophages. Compared to their non-mannosylated counterpart, the rHDL-DPM NPs delivered their payload more efficiently to the B16-F10 CM-educated RAW 264.7 macrophages. Mechanistically, both the scavenger receptor type B class 1 (SR-B1) and the mannose receptor (CD206) facilitated payload delivery to the macrophages via endocytic and non-endocytic mechanisms. Finally, the CM from rHDL-DPM-DMXAA NPs -treated macrophages enhanced paclitaxel (paclitaxel)-mediated cytotoxicity in B16-F10 cells. Together, these in vitro findings demonstrate the potential of the mannose-functionalized rHDL NPs in improving the targeting of M2-like TAMs and treatment outcomes when combined with immunotherapy or PTX in B16-F10 melanoma in vivo models.

Albendazole induces an anti-tumor effect and potentiates PD-L1 blockade immunotherapy.

Previously, albendazole (ABZ) has been reported as an anti-parasitic drug rather than anti-tumor drug. Our study aim to investigate whether ABZ also has a potential anti-tumor effect by shaping the tumor immune microenvironment and interrogate whether ABZ could synergize with the PD-L1 blockade. C57BL/6 mice (C57) were intravenously injected with B16F10-luciferase (B16-luc) cells to establish a lung metastatic melanoma model and subcutaneously inoculated with B16-luc cells to establish a subcutaneous tumor model. The tumor volume and tumor metastasis loci of the mice were measured by a vernier caliper and in vivo imaging. RNA sequencing was performed to analyze the different genes and pathways of immune cells in the tumors. Flow cytometry and immunofluorescence were used to analyze the different subsets of tumor-infiltrating immune cells. The results suggested that ABZ significantly inhibited lung melanoma metastasis with decreased fluorescence intensity and nodule score and mediated the regression of subcutaneous melanoma in mice with decreased tumor volume. Moreover, RNA sequencing results showed that ABZ regulated the gene expression levels and pathways of immune cells in the tumor microenvironment (TME). Meanwhile, flow cytometry and immunofluorescence showed that the number and percentage of CD8+ T cells, CD4+ T cells, and TH1 cells were enhanced in tumors after ABZ treatment. Furthermore, the combination of ABZ and anti-PD-L1 treatment significantly potentiated anti-tumor efficacy in both lung metastasis and subcutaneous melanoma models and mediated an increase in the percentage of CD8+ T cells, CD4+ T cells, and TH1 cells as compared to the control group. ABZ inhibits melanoma growth and metastasis. Moreover, ABZ synergized with PD-L1 blockade mediates tumor regression.

Deciphering the immune reaction leading to spontaneous melanoma regression: initial role of MHCII+ CD163− macrophages

The human cutaneous metastatic melanoma is the deadliest skin cancer. Partial, or less frequently complete spontaneous regressions could be observed, mainly mediated by T cells. Nevertheless, the underlying mechanisms are not fully unraveled. We investigated the first events of the immune response related to cancer regression in Melanoma-bearing Libechov Minipigs (MeLiM), a unique swine model of cutaneous melanoma that regresses spontaneously. Using a multiparameter flow cytometry strategy and integrating new clinical and histological criteria of the regression, we show that T cells and B cells are present only in the late stages, arguing against their role in the initial destruction of malignant cells. NK cells infiltrate the tumors before T cells and therefore might be involved in the induction of the regression process. Myeloid cells represent the main immune population within the tumor microenvironment regardless of the regression stage. Among those, MHCII+ CD163− macrophages that differ phenotypically and functionally compared to other tumor-associated macrophages, increase in number together with the first signs of regression suggesting their crucial contribution to initiating the regression process. Our study supports the importance of macrophage reprogramming in humans to improve current immunotherapy for metastatic melanoma.

Complete Stage 3 Melanoma Regression with Combination Encorafenib and Binimetinib Treatment – A Case Report and Literature Review

ABSTRACT The global incidence of melanoma is increasing at an annual growth rate of 5%. There are significant survival rate disparities, with paediatric patients having a 17% 5-year survival rate, compared to a 5% 10-year survival rate among the adult population. In Ireland, melanoma is the fourth most prevalent cancer, with 1100-1200 new cases annually. Globally, it is the sixth most frequently occurring cancer, accounting for 4% of new cancer diagnoses and 1.3% of cancer deaths in the EU-27 in 2020. Management of head-and-neck melanoma is complex and requires a multidisciplinary approach. The primary treatment is surgical excision with safety margins of 1-2 cm, and sentinel lymph node biopsy (SLNB) is recommended for staging. Adjuvant therapies include anti-PD-1 treatments and BRAF/MEK inhibitors. In this paper, we highlight the case of a 44-year-old female with stage 3 melanoma which demonstrates the potential of neoadjuvant immunotherapy with encorafenib and binimetinib. This treatment resulted in significant tumor regression, and allowed for subsequent surgical excision while preserving facial nerve function. Furthermore, postoperative outcomes showed complete regression of melanoma. This case highlights the efficacy of neoadjuvant immunotherapy in achieving significant tumor reduction, facilitating less invasive surgery, and preserving critical anatomical structures.

Intratumoral IFN-γ or topical TLR7 agonist promotes infiltration of melanoma metastases by T lymphocytes expanded in the blood after cancer vaccine

BackgroundImmune-mediated melanoma regression relies on melanoma-reactive T cells infiltrating tumor. Cancer vaccines increase circulating melanoma-reactive T cells, but little is known about vaccine-induced circulating lymphocytes (viCLs) homing to tumor or...

Spontaneous Regression of Swine Melanoma: The Role of Tumour-infiltrating T and NK Cells.

Melanoma is a skin cancer without effective therapy, showing high immunogenicity and mostly partial spontaneous regression (SR). The exact mechanisms of SR are still not well understood; therefore, the use of animal melanoma models is necessary to unravel the immunological processes during SR. Skin melanoma samples (n=57) and peripheral blood samples (n=57) from the same animals were collected. Melanoma-bearing Libechov Minipigs (MeLiM) aged 3, 4, 6, 8, 10, 12, 20, and 32 weeks were used, and samples were analysed by flow cytometry for detection of immune cell subpopulations. The proportion of CD3-CD8+ (NK) cells in melanoma samples was found to be higher compared to blood samples at 6-8 weeks of age and then at 12 weeks of age. The population of CD4+CD8+ (effector/memory T helper) cells and CD4-CD8+ (cytotoxic T and NK) cells was also increased in melanoma compared to blood samples in 10-32-week-old pigs. The proportion of CD4-CD8+ cells in melanoma samples, then augmented until the 32nd week. On the contrary, the proportion of CD4+CD8- (naive T helper) cells was lower in melanoma samples versus blood samples in 6-32-week-old animals. Cytotoxic T cells were the most abundant population of tumour infiltrating immune cells found in MeLiM melanomas of animals aged 10-32 weeks, probably causing the destruction of melanoma cells. Furthermore, the development of specific (adaptive) immune response represented mainly by cytotoxic T cells seems to be crucial for the successful SR of porcine melanoma.

Modern aspects of immunotherapy with checkpoint inhibitors in melanoma

Although melanoma is one of the most immunogenic tumors, it has an ability to evade anti-tumor immune responses by exploiting tolerance mechanisms. The most extensively studied checkpoints represent cytotoxic T lymphocyte-associated protein‑4 (CTLA‑4) and programmed cell death protein‑1 (PD‑1). Immune checkpoint inhibitors (ICI), which were broadly applied for melanoma treatment in the past decade, can unleash anti-tumor immune responses and result in melanoma regression. Patients responding to the ICI treatment showed long-lasting remission or disease control status. However, a large group of patients failed to respond to this therapy, indicating the development of resistance mechanisms. Among them are intrinsic tumor properties, the dysfunction of effector cells, and the generation of immunosuppressive tumor microenvironment (TME). This review discusses achievements of ICI treatment in melanoma, reasons for its failure, and promising approaches for overcoming the resistance. These methods include combinations of different ICI with each other, strategies for neutralizing the immunosuppressive TME and combining ICI with other anti-cancer therapies such as radiation, oncolytic viral, or targeted therapy. New therapeutic approaches targeting other immune checkpoint molecules are also discussed.

Fate mapping melanoma persister cells through regression and into recurrent disease in adult zebrafish.

ABSTRACTMelanoma heterogeneity and plasticity underlie therapy resistance. Some tumour cells possess innate resistance, while others reprogramme during drug exposure and survive to form persister cells, a source of potential cancer cells for recurrent disease. Tracing individual melanoma cell populations through tumour regression and into recurrent disease remains largely unexplored, in part, because complex animal models are required for live imaging of cell populations over time. Here, we applied tamoxifen-inducible creERt2/loxP lineage tracing to a zebrafish model of MITF-dependent melanoma regression and recurrence to image and trace cell populations in vivo through disease stages. Using this strategy, we show that melanoma persister cells at the minimal residual disease site originate from the primary tumour. Next, we fate mapped rare MITF-independent persister cells and demonstrate that these cells directly contribute to progressive disease. Multiplex immunohistochemistry confirmed that MITF-independent persister cells give rise to Mitfa+ cells in recurrent disease. Taken together, our work reveals a direct contribution of persister cell populations to recurrent disease, and provides a resource for lineage-tracing methodology in adult zebrafish cancer models.