Long-term outcomes in patients with advanced melanoma who had initial stable disease with pembrolizumab in KEYNOTE-001 and KEYNOTE-006

The path to leptomeningeal metastasis

The leptomeninges, the cerebrospinal-fluid-filled tissues surrounding the central nervous system, play host to various pathologies including infection, neuroinflammation and malignancy. Spread of systemic cancer into this space, termed leptomeningeal metastasis, occurs in 5-10% of patients with solid tumours and portends a bleak clinical prognosis. Previous, predominantly descriptive, clinical studies have provided few insights. Recent development of preclinical leptomeningeal metastasis models, alongside genomic, transcriptomic and proteomic sequencing efforts, has provided groundwork for mechanistic understanding and identification of long-needed therapeutic targets. Although previously understood as an anatomically isolated compartment, the leptomeninges are increasingly appreciated as a major conduit of communication between the systemic circulation and the central nervous system. Despite the unique nature of the leptomeningeal microenvironment, the general principles of metastasis hold true: cells metastasizing to the leptomeninges must gain access to the new environment, survive within the space and evade the immune system. The study of leptomeningeal metastasis has the potential to uncover novel site-specific metastatic principles and illuminate the physiology of the leptomeningeal space. In this Review, we provide a biology-focused overview of how metastatic cells reach the leptomeninges, thrive in this nutritionally sparse environment and evade the detection of the omnipresent immune system.

The Use of Fecal Microbiota Transplant in Overcoming and Modulating Resistance to Anti-PD-1 Therapy in Patients with Skin Cancer

While immune checkpoint inhibitors have evolved into the standard of care for advanced melanoma, 40-50% of melanoma cases progress while on therapies. The relationship between bacterium and carcinogenesis is well founded, such as in H. pylori in gastric cancers, and Fusobacterium in colorectal cancers. This interplay between dysbiosis and carcinogenesis questions whether changes in the microbiome could affect treatment. Thus, FMT may find utility in modifying the efficacy of anti-PD-1. This review aims to examine the use of FMT in treatment-resistant melanoma. A literature search was performed using the keywords "fecal microbiota transplant" and "skin cancer". Studies were reviewed for inclusion criteria and quality and in the final stage, and three studies were included. Overall objective responses were reported in 65% of patients who were able to achieve CR, and 45% who achieved PR. Clinical benefit rate of combined CR/PR with stable disease greater or equal to 6 months was 75%. Reported objective responses found durable stable disease lasting 12 months. Overall survival was 7 months, and overall PRS was 3 months. As for the evaluation of safety, many patients reported grade 1-2 FMT related AE. Only following the administration of anti-PD-1 therapy were there a grade 3 or higher AE.

Predictive Factors in Metastatic Melanoma Treated with Immune Checkpoint Inhibitors: From Clinical Practice to Future Perspective

The introduction of immunotherapy revolutionized the treatment landscape in metastatic melanoma. Despite the impressive results associated with immune checkpoint inhibitors (ICIs), only a portion of patients obtain a response to this treatment. In this scenario, the research of predictive factors is fundamental to identify patients who may have a response and to exclude patients with a low possibility to respond. These factors can be host-associated, immune system activation-related, and tumor-related. Patient-related factors can vary from data obtained by medical history (performance status, age, sex, body mass index, concomitant medications, and comorbidities) to analysis of the gut microbiome from fecal samples. Tumor-related factors can reflect tumor burden (metastatic sites, lactate dehydrogenase, C-reactive protein, and circulating tumor DNA) or can derive from the analysis of tumor samples (driver mutations, tumor-infiltrating lymphocytes, and myeloid cells). Biomarkers evaluating the immune system activation, such as IFN-gamma gene expression profile and analysis of circulating immune cell subsets, have emerged in recent years as significantly correlated with response to ICIs. In this manuscript, we critically reviewed the most updated literature data on the landscape of predictive factors in metastatic melanoma treated with ICIs. We focus on the principal limits and potentiality of different methods, shedding light on the more promising biomarkers.

Transport Barriers Influence the Activation of Anti-Tumor Immunity: A Systems Biology Analysis

Effective anti-cancer immune responses require activation of one or more naïve T cells. If the correct naïve T cell encounters its cognate antigen presented by an antigen presenting cell, then the T cell can activate and proliferate. Here, mathematical modeling is used to explore the possibility that immune activation in lymph nodes is a rate-limiting step in anti-cancer immunity and can affect response rates to immune checkpoint therapy. The model provides a mechanistic framework for optimizing cancer immunotherapy and developing testable solutions to unleash anti-tumor immune responses for more patients with cancer. The results show that antigen production rate and trafficking of naïve T cells into the lymph nodes are key parameters and that treatments designed to enhance tumor antigen production can improve immune checkpoint therapies. The model underscores the potential of radiation therapy in augmenting tumor immunogenicity and neoantigen production for improved ICB therapy, while emphasizing the need for careful consideration in cases where antigen levels are already sufficient to avoid compromising the immune response.

Decoding the metastatic potential and optimal postoperative adjuvant therapy of melanoma based on metastasis score

Metastasis is a formidable challenge in the prognosis of melanoma. Accurately predicting the metastatic potential of non-metastatic melanoma (NMM) and determining effective postoperative adjuvant treatments for inhibiting metastasis remain uncertain. In this study, we conducted comprehensive analyses of melanoma metastases using bulk and single-cell RNA sequencing data, enabling the construction of a metastasis score (MET score) through diverse machine-learning algorithms. The reliability and robustness of the MET score were validated using various in vitro assays and in vivo models. Our findings revealed a distinct molecular landscape in metastatic melanoma characterized by the enrichment of metastasis-related pathways, intricate cell-cell communication, and heightened infiltration of pro-angiogenic tumor-associated macrophages compared to NMM. Importantly, patients in the high MET score group exhibited poorer prognoses and an immunosuppressive microenvironment, featuring increased infiltration of regulatory T cells and decreased infiltration of CD8+ T cells, compared to the low MET score patient group. Expression of PD-1 was markedly higher in patients with low MET scores. Anti-PD-1 (aPD-1) therapy profoundly affected antitumor immunity activation and metastasis inhibition in these patients. In summary, our study demonstrates the effectiveness of the MET score in predicting melanoma metastatic potential. For patients with low MET scores, aPD-1 therapy may be a potential treatment strategy to inhibit metastasis. Patients with high MET scores may benefit from combination therapies.

A Spontaneous Melanoma Mouse Model Applicable for a Longitudinal Chemotherapy and Immunotherapy Study

Mouse models that reflect human disorders provide invaluable tools for the translation of basic science discoveries to clinical therapies. However, many of these in vivo therapeutic studies are short term and do not accurately mimic patient conditions. In this study, we used a fully immunocompetent, transgenic mouse model, TGS, in which the spontaneous development of metastatic melanoma is driven by the ectopic expression of a normal neuronal receptor, mGluR1, as a model to assess longitudinal treatment response (up to 8 months) with an inhibitor of glutamatergic signaling, troriluzole, which is a prodrug of riluzole, plus an antibody against PD-1, an immune checkpoint inhibitor. Our results reveal a sex-biased treatment response that led to improved survival in troriluzole and/or anti-PD-1-treated male mice that correlated with differential CD8+ T cells and CD11b+ myeloid cell populations in the tumor-stromal interface, supporting the notion that this model is a responsive and tractable system for evaluating therapeutic regimens for melanoma in an immunocompetent setting.

Immune checkpoint HLA-E:CD94-NKG2A mediates evasion of circulating tumor cells from NK cell surveillance

Circulating tumor cells (CTCs), shed by primary malignancies, function as "seeds" for distant metastasis. However, it is still largely unknown how CTCs escape immune surveillance. Here, we characterize the transcriptomes of human pancreatic ductal adenocarcinoma CTCs, primary, and metastatic lesions at single-cell scale. Cell-interaction analysis and functional studies in vitro and in vivo reveal that CTCs and natural killer (NK) cells interact via the immune checkpoint molecule pair HLA-E:CD94-NKG2A. Disruption of this interaction by blockade of NKG2A or knockdown of HLA-E expression enhances NK-mediated tumor cell killing in vitro and prevents tumor metastasis in vivo. Mechanistic studies indicate that platelet-derived RGS18 promotes the expression of HLA-E through AKT-GSK3β-CREB signaling, and overexpression of RGS18 facilitates pancreatic tumor hepatic metastasis. In conclusion, platelet-derived RGS18 protects CTCs from NK-mediated immune surveillance by engaging the immune checkpoint HLA-E:CD94-NKG2A. Interruption of the suppressive signaling prevents tumor metastasis in vivo by immune elimination of CTCs.

KEYNOTE - D36: personalized immunotherapy with a neoepitope vaccine, EVX-01 and pembrolizumab in advanced melanoma

Despite improvements made with checkpoint inhibitor (CPI) therapy, a need for new approaches to improve outcomes for patients with unresectable or metastatic melanoma remains. EVX-01, a personalized neoepitope vaccine, combined with pembrolizumab treatment, holds the potential to fulfill this need. Here we present the rationale and novel design behind the KEYNOTE - D36 trial: an open label, single arm, phase II trial aiming to establish the clinical proof of concept and evaluate the safety of EVX-01 in combination with pembrolizumab in CPI naive patients with unresectable or metastatic melanoma. The primary objective is to evaluate if EVX-01 improves best overall response after initial stable disease or partial response to pembrolizumab treatment, in patients with advanced melanoma. The novel end points ensure a decisive readout which may prove helpful before making major investments in phase III trials with limited phase I data. Clinical Trial Registration: NCT05309421 (ClinicalTrials.gov).

What is the optimal duration of immune checkpoint inhibitors in malignant tumors?

Immunotherapy, represented by immune checkpoint inhibitors (ICIs), has made a revolutionary difference in the treatment of malignant tumors, and considerably extended patients' overall survival (OS). In the world medical profession, however, there still reaches no clear consensus on the optimal duration of ICIs therapy. As reported, immunotherapy response patterns, immune-related adverse events (irAEs) and tumor stages are all related to the diversity of ICIs duration in previous researches. Besides, there lacks clear clinical guidance on the intermittent or continuous use of ICIs. This review aims to discuss the optimal duration of ICIs, hoping to help guide clinical work based on the literature.

Loss of MHC-I antigen presentation correlated with immune checkpoint blockade tolerance in MAPK inhibitor-resistant melanoma

Immune checkpoint blockade and MAPK-targeted combined therapy is a promising regimen for advanced melanoma patients. However, the clinical benefit from this combo regimen remains limited, especially in patients who acquired resistance to MAPK-targeted therapy. Here, we systematically characterized the immune landscape during MAPK-targeted therapy in patients and mouse melanoma models. We observed that both the abundance of tumor-infiltrated T cells and the expression of immune-related genes were upregulated in the drug-responsive period, but downregulated in the resistance period, implying that acquired drug resistance dampens the antitumor immune response. Further transcriptomic dissection indicated that loss of MHC-I antigen presentation on tumor cells plays a critical role in the reduction of T cell infiltration during drug resistance. Survival analysis demonstrates that loss of antigen presentation and reduction of T-cell infiltration during acquired drug resistance are associated with poorer clinical response and prognosis of anti-PD-1 therapy in melanoma patients. In addition, we identified that alterations in the MAPK inhibitor resistance-related oncogenic signaling pathway closely correlated with deficiency of MHC-I antigen presentation, including activation of the PI3K-mTOR, MAPK, and Wnt pathways. In conclusion, our research illuminates that decreased infiltration of T cells is associated with acquired drug resistance during MAPK-targeted therapy, which may underlie the cross-resistance to immune checkpoint blockade.

Anti-PD-1 Monotherapy in Advanced Melanoma—Real-World Data from a 77-Month-Long Retrospective Observational Study

Real-world evidence plays an important role in the assessment of efficacy and safety of novel therapies. The increasing use of immune checkpoint inhibitors (ICIs) in patients with advanced melanoma has led to notably improved clinical outcomes, while they are also associated with immune-related adverse events (irAEs). The majority of the available data are based on clinical trials, where the investigated subjects often do not adequately represent the general patient population of the everyday practice. Although there is a niche of objective biomarkers for the future treatment response of ICIs, certain studies suggest that irAEs may be predictive. The aim of this study was to carry out a retrospective analysis of treatment data from patients with advanced melanoma, treated with a single anti-PD-1 agent (pembrolizumab or nivolumab) during a 77-month-long period. Treatment efficacy and occurrence of adverse events were analyzed to identify potential predictive markers. Primary and secondary endpoints were the overall survival (OS) and progression-free survival (PFS). In our cohort, we demonstrated that the occurrence of more than one irAE showed a correlation with response to PD-1 ICI therapy and improved the OS and PFS. Our study suggests, that the grade of toxicity of the irAE may affect the survival rate.

The "Great Debate" at Immunotherapy Bridge 2021, December 1st-2nd, 2021

As part of the 2021 Immunotherapy Bridge virtual congress (December 1–2, Naples, Italy), the Great Debate sessions featured experts who were assigned counter opposing views on four important questions in immunotherapy today. The first topic was whether oncolytic viruses or other specific immunomodulators were the more promising approach for intralesional therapy. The second was whether early surrogate endpoints, such as response rate or progression-free survival, correlate with long-term overall survival was considered. Thirdly, whether vaccines can transform cold into hot tumors was discussed and, finally, broad versus deep analytic profiling approaches to gain insights into immune-oncology development were compared. As with previous Bridge congresses, presenters were invited by the meeting Chairs and positions taken during the debates may not have reflected their respective personal view. In addition, the views summarised in this article are based on available evidence but may reflect personal interpretation of these data, clinical experience and subjective opinion of the speaker.