Melanoma vaccines: mixed past, promising future

Immunotherapy and delivery systems for melanoma

Melanoma is a highly malignant tumor of melanocyte origin that is prone to early metastasis and has a very poor prognosis. Early melanoma treatment modalities are mainly surgical, and treatment strategies for advanced or metastatic melanoma contain chemotherapy, radiotherapy, targeted therapy and immunotherapy. The efficacy of chemotherapy and radiotherapy has been unsatisfactory due to low sensitivity and strong toxic side effects. And targeted therapy is prone to drug resistance, so its clinical application is limited. Melanoma has always been the leader of immunotherapy for solid tumors, and how to maximize the role of immunotherapy and how to implement immunotherapy more accurately are still urgent to be explored. This review summarizes the common immunotherapies and applications for melanoma, illustrates the current research status of melanoma immunotherapy delivery systems, and discusses the advantages and disadvantages of each delivery system and its prospects for clinical application.

Immunotherapy for Cutaneous Squamous Cell Carcinoma: Results and Perspectives

Although initial surgical excision cures 95% of patients, a minority of cutaneous squamous cell carcinomas (cSCCs) are judged to be unresectable, either locally advanced or with unresectable regional lymph nodes or distant metastases. These patients are offered systemic treatments. Response rate to chemotherapy is relatively low and not durable, as well as the results obtained with epidermal growth factor inhibitors (EGFRi). Like other cutaneous tumors, cSCCs have high immunogenicity, driven by the high mutational burden, the ultraviolet signature, and the overexpressed tumor antigens. Two checkpoint inhibitors, cemiplimab and pembrolizumab, achieved high response rate and survival with fewer toxicities than other available systemic agents. These promising results prompted to investigate new combination strategies of systemic therapy and surgery or radiotherapy. Subgroup analysis showed promising role of immunotherapy to facilitate surgery in locally advanced cSCC and, in a small group of patients, long-term survivals without resection. However, some cSCCs treated with immunotherapy develop either early or late resistance, so new drugs and new combinations are in a clinical study to overcome the mechanism underpinning these resistances. The present review focuses on the progress with immunotherapy to date and on new therapeutic strategies for cSCC.

Targeting Cross-Presentation as a Route to Improve the Efficiency of Peptide-Based Cancer Vaccines

Cross-presenting dendritic cells (DC) offer an attractive target for vaccination due to their unique ability to process exogenous antigens for presentation on MHC class I molecules. Recent reports have established that these DC express unique surface receptors and play a critical role in the initiation of anti-tumor immunity, opening the way for the development of vaccination strategies specifically targeting these cells. This study investigated whether targeting cross-presenting DC by two complementary mechanisms could improve vaccine effectiveness, in both a viral setting and in a murine melanoma model. Our novel vaccine construct contained the XCL1 ligand, to target uptake to XCR1+ cross-presenting DC, and a cell penetrating peptide (CPP) with endosomal escape properties, to enhance antigen delivery into the cross-presentation pathway. Using a prime-boost regimen, we demonstrated robust expansion of antigen-specific T cells following vaccination with our CPP-linked peptide vaccine and protective immunity against HSV-1 skin infection, where vaccine epitopes were natively expressed by the virus. Additionally, our novel vaccination strategy slowed tumor outgrowth in a B16 murine melanoma model, compared to adjuvant only controls, suggesting antigen-specific anti-tumor immunity was generated following vaccination. These findings suggest that novel strategies to target the antigen cross-presentation pathway in DC may be beneficial for the generation of anti-tumor immunity.

The role of immunogenic cell death in gastrointestinal cancer immunotherapy (Review)

Modern cancer immunotherapy techniques are aimed at enhancing the responses of the patients' immune systems to fight against the cancer. The main promising strategies include active vaccination of tumor antigens, passive vaccination with antibodies specific to cancer antigens, adoptive transfer of cancer-specific T cells and manipulation of the patient's immune response by inhibiting immune checkpoints. The application of immunogenic cell death (ICD) inducers has been proven to enhance the immunity of patients undergoing various types of immunotherapy. The dying, stressed or injured cells release or present molecules on the cell surface, which function as either adjuvants or danger signals for detection by the innate immune system. These molecules are now termed 'damage-associated molecular patterns'. The term 'ICD' indicates a type of cell death that triggers an immune response against dead-cell antigens, particularly those derived from cancer cells, and it was initially proposed with regards to the effects of anticancer chemotherapy with conventional cytotoxic drugs. The aim of the present study was to review and discuss the role and mechanisms of ICD as a promising combined immunotherapy for gastrointestinal tumors.

Targeted Immunotherapies in Gastrointestinal Cancer: From Molecular Mechanisms to Implications

Gastrointestinal cancer is a leading cause of cancer-related mortality and remains a major challenge for cancer treatment. Despite the combined administration of modern surgical techniques and chemoradiotherapy (CRT), the overall 5-year survival rate of gastrointestinal cancer patients in advanced stage disease is less than 15%, due to rapid disease progression, metastasis, and CRT resistance. A better understanding of the mechanisms underlying cancer progression and optimized treatment strategies for gastrointestinal cancer are urgently needed. With increasing evidence highlighting the protective role of immune responses in cancer initiation and progression, immunotherapy has become a hot research topic in the integrative management of gastrointestinal cancer. Here, an overview of the molecular understanding of colorectal cancer, esophageal cancer and gastric cancer is provided. Subsequently, recently developed immunotherapy strategies, including immune checkpoint inhibitors, chimeric antigen receptor T cell therapies, tumor vaccines and therapies targeting other immune cells, have been described. Finally, the underlying mechanisms, fundamental research and clinical trials of each agent are discussed. Overall, this review summarizes recent advances and future directions for immunotherapy for patients with gastrointestinal malignancies.

Hitchhiking on Controlled-Release Drug Delivery Systems: Opportunities and Challenges for Cancer Vaccines

Cancer vaccines represent among the most promising strategies in the battle against cancers. However, the clinical efficacy of current cancer vaccines is largely limited by the lack of optimized delivery systems to generate strong and persistent antitumor immune responses. Moreover, most cancer vaccines require multiple injections to boost the immune responses, leading to poor patient compliance. Controlled-release drug delivery systems are able to address these issues by presenting drugs in a controlled spatiotemporal manner, which allows co-delivery of multiple drugs, reduction of dosing frequency and avoidance of significant systemic toxicities. In this review, we outline the recent progress in cancer vaccines including subunit vaccines, genetic vaccines, dendritic cell-based vaccines, tumor cell-based vaccines and in situ vaccines. Furthermore, we highlight the efforts and challenges of controlled or sustained release drug delivery systems (e.g., microparticles, scaffolds, injectable gels, and microneedles) in ameliorating the safety, effectiveness and operability of cancer vaccines. Finally, we briefly discuss the correlations of vaccine release kinetics and the immune responses to enlighten the rational design of the next-generation platforms for cancer therapy.

State of Melanoma: An Historic Overview of a Field in Transition

The management of melanoma significantly improved within the last 25 years. Chemotherapy was the first approved systemic therapeutic approach and resulted in a median overall of survival less than 1 year, without survival improvement in phase III trials. High-dose interferon α2b and IL-2 were introduced for resectable high-risk and advanced disease, respectively, resulting in improved survival and response rates. The anti-CTLA4 and anti-programmed death 1 monoclonal antibodies along with BRAF/MEK targeted therapies are the dominant therapeutic classes of agent for melanoma. This article provides an historic overview of the evolution of melanoma management.

A Phase IIb Randomized Controlled Trial of the TLPLDC Vaccine as Adjuvant Therapy After Surgical Resection of Stage III/IV Melanoma: A Primary Analysis

Background

Melanoma therapy has changed dramatically over the last decade with improvements in immunotherapy, yet many patients do not respond to current therapies. This novel vaccine strategy may prime a patient’s immune system against their tumor and work synergistically with immunotherapy against advanced-stage melanoma.

Methods

This was a prospective, randomized, double-blind, placebo-controlled, phase IIb trial of the tumor lysate, particle-loaded, dendritic cell (TLPLDC) vaccine administered to prevent recurrence in patients with resected stage III/IV melanoma. Patients were enrolled and randomized 2:1 to the TLPLDC vaccine or placebo (empty yeast cell wall particles and autologous dendritic cells). Both intention-to-treat (ITT) and per treatment (PT) analyses were predefined, with PT analysis including patients who remained disease-free through the primary vaccine/placebo series (6 months).

Results

A total of 144 patients were randomized (103 vaccine, 41 control). Therapy was well-tolerated with similar toxicity between treatment arms; one patient in each group experienced related serious adverse events. While disease-free survival (DFS) was not different between groups in ITT analysis, in PT analysis the vaccine group showed improved 24-month DFS (62.9% vs. 34.8%, p = 0.041).

Conclusions

This phase IIb trial of TLPLDC vaccine administered to patients with resected stage III/IV melanoma shows TLPLDC is well-tolerated and improves DFS in patients who complete the primary vaccine series. This suggests patients who do not recur early benefit from TLPLDC in preventing future recurrence from melanoma. A phase III trial of TLPLDC + checkpoint inhibitor versus checkpoint inhibitor alone in patients with advanced, surgically resected melanoma is under development.

Trial Registration

NCT02301611.

Supplementary information

The online version contains supplementary material available at (10.1245/s10434-021-09709-1).

An Overview of Advances in Cell-Based Cancer Immunotherapies Based on the Multiple Immune-Cancer Cell Interactions

Tumors have a complex ecosystem in which behavior and fate are determined by the interaction of diverse cancerous and noncancerous cells at local and systemic levels. A number of studies indicate that various immune cells participate in tumor development (Fig. 1). In this review, we will discuss interactions among T lymphocytes (T cells), B cells, natural killer (NK) cells, dendritic cells (DCs), tumor-associated macrophages (TAMs), neutrophils, and myeloid-derived suppressor cells (MDSCs). In addition, we will touch upon attempts to either use or block subsets of immune cells to target cancer.

Current Advancements and Novel Strategies in the Treatment of Metastatic Melanoma

Melanoma is the deadliest form of skin cancer in the world with a growing incidence in North America. Contemporary treatments for melanoma include surgical resection, chemotherapy, and radiotherapy. However, apart from resection in early melanoma, the prognosis of patients using these treatments is typically poor. In the past decade, there have been significant advancements in melanoma therapies. Immunotherapies such as ipilimumab and targeted therapies such as vemurafenib have emerged as a promising option for patients as seen in both scientific and clinical research. Furthermore, combination therapies are starting to be administered in the form of polychemotherapy, polyimmunotherapy, and biochemotherapy, of which some have shown promising outcomes in relative efficacy and safety due to their multiple targets. Alongside these treatments, new research has been conducted into the evidence-based use of natural health products (NHPs) and natural compounds (NCs) on melanoma which may provide a long-term and non-toxic form of complementary therapy. Nevertheless, there is a limited consolidation of the research conducted in emerging melanoma treatments which may be useful for researchers and clinicians. Thus, this review attempts to evaluate the therapeutic efficacy of current advancements in metastatic melanoma treatment by surveying new research into the molecular and cellular basis of treatments along with their clinical efficacy. In addition, this review aims to elucidate novel strategies that are currently being used and have the potential to be used in the future.

Multi-Omics and Informatics Analysis of FFPE Tissues Derived from Melanoma Patients with Long/Short Responses to Anti-PD1 Therapy Reveals Pathways of Response

Simple Summary

Immune based therapies have benefited many melanoma patients, but many patients still do not respond. This study analyzes biospecimens obtained from patients undergoing a type of immune based therapy called anti-PD-1 to understand mechanisms of response and resistance to this treatment. The operational definition of good response utilized in this investigation permitted us to examine the biochemical pathways that are facilitating anti-PD-1 responses independent of prior therapies received by patients. Currently, there are no clinically available tests to reliably test for the outcome of patients treated with anti-PD-1 therapy. The purpose of this study was to facilitate the development of prospective biomarker-directed trials to guide therapy, as even though the side effect profile is favorable for anti-PD-1 therapy, some patients do not respond to therapy with significant toxicity. Each patient may require testing for the pathways upregulated in the tumor to predict optimal benefit to anti-PD-1 treatment.

Abstract

Anti-PD-1 based immune therapies are thought to be dependent on antigen processing and presentation mechanisms. To characterize the immune-dependent mechanisms that predispose stage III/IV melanoma patients to respond to anti-PD-1 therapies, we performed a multi-omics study consisting of expression proteomics and targeted immune-oncology-based mRNA sequencing. Formalin-fixed paraffin-embedded tissue samples were obtained from stage III/IV patients with melanoma prior to anti-PD-1 therapy. The patients were first stratified into poor and good responders based on whether their tumors had or had not progressed while on anti-PD-1 therapy for 1 year. We identified 263 protein/gene candidates that displayed differential expression, of which 223 were identified via proteomics and 40 via targeted-mRNA analyses. The downstream analyses of expression profiles using MetaCore software demonstrated an enrichment of immune system pathways involved in antigen processing/presentation and cytokine production/signaling. Pathway analyses showed interferon (IFN)-γ-mediated signaling via NF-κB and JAK/STAT pathways to affect immune processes in a cell-specific manner and to interact with the inducible nitric oxide synthase. We review these findings within the context of available literature on the efficacy of anti-PD-1 therapy. The comparison of good and poor responders, using efficacy of PD-1-based therapy at 1 year, elucidated the role of antigen presentation in mediating response or resistance to anti-PD-1 blockade.

Immunotherapy of Melanoma: Facts and Hopes

Melanoma is among the most sensitive of malignancies to immune modulation. Although multiple trials conducted over decades with vaccines, cytokines, and cell therapies demonstrated meaningful responses in a small subset of patients with metastatic disease, a true increase in overall survival (OS) within a randomized phase III trial was not observed until the development of anti-CTLA-4 (ipilimumab). Further improvements in OS for metastatic disease were observed with the anti-PD-1-based therapies (nivolumab, pembrolizumab) as single agents or combined with ipilimumab. A lower bound for expected 5-year survival for metastatic melanoma is currently approximately 35% and could be as high as 50% for the nivolumab/ipilimumab combination among patients who would meet criteria for clinical trials. Moreover, a substantial fraction of long-term survivors will likely remain progression-free without continued treatment. The hope and major challenge for the future is to understand the immunobiology of tumors with primary or acquired resistance to anti-PD-1 or anti-PD-1/anti-CTLA-4 and to develop effective immune therapies tailored to individual patient subsets not achieving long-term clinical benefit. Additional goals include optimal integration of immune therapy with nonimmune therapies, the development and validation of predictive biomarkers in the metastatic setting, improved prognostic and predictive biomarkers for the adjuvant setting, understanding mechanisms of and decreasing toxicity, and optimizing the duration of therapy.

Pentaerythritol-based lipid A bolsters the antitumor efficacy of a polyanhydride particle-based cancer vaccine

The primary objective of this study was to enhance the antitumor efficacy of a model cancer vaccine through co-delivery of pentaerythritol lipid A (PELA), an immunological adjuvant, and a model tumor antigen, ovalbumin (OVA), separately loaded into polyanhydride particles (PA). In vitro experiments showed that encapsulation of PELA into PA (PA-PELA) significantly enhanced its stimulatory capacity on dendritic cells as evidenced by increased levels of the cell surface costimulatory molecules, CD80/CD86. In vivo experiments showed that PA-PELA, in combination with OVA-loaded PA (PA-OVA), significantly expanded the OVA-specific CD8⁺ T lymphocyte population compared to PA-OVA alone. Furthermore, OVA-specific serum antibody titers of mice vaccinated with PA-OVA/PA-PELA displayed a significantly stronger shift toward a Th1-biased immune response compared to PA-OVA alone, as evidenced by the substantially higher IgG_2C:IgG₁ ratios achieved by the former. Analysis of E.G7-OVA tumor growth curves showed that mice vaccinated with PA-OVA/PA-PELA had the slowest average tumor growth rate.

Combining Tumor Vaccination and Oncolytic Viral Approaches with Checkpoint Inhibitors: Rationale, Pre-Clinical Experience, and Current Clinical Trials in Malignant Melanoma

The field of tumor immunology has faced many complex challenges over the last century, but the approval of immune checkpoint inhibitors (anti-cytotoxic T-lymphocyte-associated protein 4 [CTLA4] and anti-programmed cell death-1 [PD-1]/PD-ligand 1 [PD-L1]) and talimogene laherparepvec (T-VEC) for the treatment of metastatic melanoma have awakened a new wave of interest in cancer immunotherapy. Additionally, combinations of vaccines and oncolytic viral therapies with immune checkpoint inhibitors and other systemic agents seem to be promising synergistic strategies to further boost the immune response against cancer. These combinations are undergoing clinical investigation, and if successful, will hopefully soon become available to patients. Here, we review key basic concepts of tumor-induced immune suppression in malignant melanoma, the historical perspective around vaccine development in melanoma, and advances in oncolytic viral therapies. We also discuss the emerging role for combination approaches with different immunomodulatory agents as well as new developments in personalized immunization approaches.

Self-Assembled, Adjuvant/Antigen-Based Nanovaccine Mediates Anti-Tumor Immune Response against Melanoma Tumor

Malignant melanoma is a highly aggressive type of cancer that requires radical treatment strategies to inhibit the cancer cell progression and metastasis. In recent years, preclinical research and clinical trials on melanoma treatment have been considerably focused on the adjuvant-based immunotherapy for enhancing the immune response of innate immune cells against cancer cells. However, the clinical outcome of these adjuvant-based treatments is inadequate due to an improper delivery system for these immune activators to reach the target site. Hence, we developed a vaccine formulation containing tumor lysate protein (TL) and poly I:C (PIC) complexed with positively charged poly (sorbitol-co-polyethylenimine (PEI) (PSPEI). The resulting ionic PSPEI-polyplexed antigen/adjuvant (PAA) (PSPEI-PAA) nanocomplexes were stable at the physiological condition, are non-toxic, and have enhanced intracellular uptake of antigen and adjuvant in immature dendritic cells leading to dendritic cell maturation. In the murine B16F10 tumor xenograft model, PSPEI-PAA nanocomplexes significantly suppressed tumor growth and did not exhibit any noticeable sign of toxicity. The level of matured dendritic cells (CD80+/CD86+ cells) in the tumor draining lymph node of PSPEI-PAA treated tumor mice were enhanced and therefore CD8+ T cells infiltration in the tumor were enriched. Additionally, the cytotoxic T lymphocytes (CTLs) assay involving co-culturing of splenocytes isolated from the PSPEI-PAA-treated mice with that of B16F10 cells significantly revealed enhanced cancer killing by the TL-reactivated CTLs compared to untreated control mice bearing tumor. Therefore, we strongly believe that PSPEI-PAA nanocomplexes could be an efficient antigen/adjuvant delivery system and enhance the antitumor immune response against melanoma tumor in the future clinical trials.

Updates on the use of vaccines in dermatological conditions

Numerous vaccines are being actively developed for use in dermatologic diseases. Advances in the fields of immunotherapy, genetics and molecular medicine have allowed for the design of prophylactic and therapeutic vaccines with immense potential in managing infections and malignancies of the skin. This review addresses the different vaccines available for use in dermatological diseases and those under development for future potential use. The major limitation of our review is its complete reliance on published data. Our review is strictly limited to the availability of published research online through available databases. We do not cite any of the authors' previous publications nor have we conducted previous original research studies regarding vaccines in dermatology. Strength would have been added to our paper had we conducted original studies by our research team regarding the candidate vaccines delineated in the paper.

MECHANISMS IN ENDOCRINOLOGY: Lessons from growth hormone receptor gene-disrupted mice: are there benefits of endocrine defects?

Growth hormone (GH) is produced primarily by anterior pituitary somatotroph cells. Numerous acute human (h) GH treatment and long-term follow-up studies and extensive use of animal models of GH action have shaped the body of GH research over the past 70 years. Work on the GH receptor (R)-knockout (GHRKO) mice and results of studies on GH-resistant Laron Syndrome (LS) patients have helped define many physiological actions of GH including those dealing with metabolism, obesity, cancer, diabetes, cognition and aging/longevity. In this review, we have discussed several issues dealing with these biological effects of GH and attempt to answer the question of whether decreased GH action may be beneficial.

B4GALNT2 and xenotransplantation: A newly appreciated xenogeneic antigen

Analysis of non‐Gal antibody induced after pig‐to‐baboon cardiac xenotransplantation identified the glycan produced by porcine beta‐1,4‐N‐acetyl‐galactosaminyltransferase 2 (B4GALNT2) as an immunogenic xenotransplantation antigen. The porcine B4GALNT2 enzyme is homologous to the human enzyme, which synthesizes the human SDa blood group antigen. Most humans produce low levels of anti‐SDa IgM which polyagglutinates red blood cells from rare individuals with high levels of SDa expression. The SDa glycan is also present on GM2 gangliosides. Clinical GM2 vaccination studies for melanoma patients suggest that a human antibody response to SDa can be induced. Expression of porcine B4GALNT2 in human HEK293 cells results in increased binding of anti‐SDa antibody and increased binding of Dolichos biflorus agglutinin (DBA), a lectin commonly used to detect SDa. In pigs, B4GALNT2 is expressed by vascular endothelial cells and endothelial cells from a wide variety of pig backgrounds stain with DBA, suggesting that porcine vascular expression of B4GALNT2 is not polymorphic. Mutations in B4GALNT2 have been engineered in mice and pigs. In both species, the B4GALNT2‐KO animals are apparently normal and no longer show evidence of SDa antigen expression. Pig tissues with a mutation in B4GALNT2, added to a background of alpha‐1,3‐galactosyltransferase deficient (GGTA1‐KO) and cytidine monophosphate‐N‐acetylneuraminic acid hydroxylase deficient (CMAH‐KO), show reduced antibody binding, confirming the presence of B4GALNT2‐dependent antibodies in both humans and non‐human primates. Preclinical xenotransplantation using B4GALNT2‐deficient donors has recently been reported. Elimination of this source of immunogenic pig antigen should minimize acute injury by preformed anti‐pig antibody and eliminate an induced clinical immune response to this newly appreciated xenotransplantation antigen.

Immunotherapy Plus Cryotherapy: Potential Augmented Abscopal Effect for Advanced Cancers

Since the 1920s the gold standard for treating cancer has been surgery, which is typically preceded or followed with chemotherapy and/or radiation, a process that perhaps contributes to the destruction of a patient’s immune defense system. Cryosurgery ablation of a solid tumor is mechanistically similar to a vaccination where hundreds of unique antigens from a heterogeneous population of tumor cells derived from the invading cancer are released. However, releasing tumor-derived self-antigens into circulation may not be sufficient enough to overcome the checkpoint escape mechanisms some cancers have evolved to avoid immune responses. The potentiated immune response caused by blocking tumor checkpoints designed to prevent programmed cell death may be the optimal treatment method for the immune system to recognize these new circulating cryoablated self-antigens. Preclinical and clinical evidence exists for the complementary roles for Cytotoxic T-lymphocyte-associated protein (CTLA-4) and PD-1 antagonists in regulating adaptive immunity, demonstrating that combination immunotherapy followed by cryosurgery provides a more targeted immune response to distant lesions, a phenomenon known as the abscopal effect. We propose that when the host’s immune system has been “primed” with combined anti-CTLA-4 and anti-PD-1 adjuvants prior to cryosurgery, the preserved cryoablated tumor antigens will be presented and processed by the host’s immune system resulting in a robust cytotoxic CD8⁺ T-cell response. Based on recent investigations and well-described biochemical mechanisms presented herein, a polyvalent autoinoculation of many tumor-specific antigens, derived from a heterogeneous population of tumor cancer cells, would present to an unhindered yet pre-sensitized immune system yielding a superior advantage in locating, recognizing, and destroying tumor cells throughout the body.

Growth Hormone Receptor Knockdown Sensitizes Human Melanoma Cells to Chemotherapy by Attenuating Expression of ABC Drug Efflux Pumps

Melanoma remains one of the most therapy-resistant forms of human cancer despite recent introductions of highly efficacious targeted therapies. The intrinsic therapy resistance of human melanoma is largely due to abundant expression of a repertoire of xenobiotic efflux pumps of the ATP-binding cassette (ABC) transporter family. Here, we report that GH action is a key mediator of chemotherapeutic resistance in human melanoma cells. We investigated multiple ABC efflux pumps (ABCB1, ABCB5, ABCB8, ABCC1, ABCC2, ABCG1, and ABCG2) reportedly associated with melanoma drug resistance in different human melanoma cells and tested the efficacy of five different anti-cancer compounds (cisplatin, doxorubicin, oridonin, paclitaxel, vemurafenib) with decreased GH action. We found that GH treatment of human melanoma cells upregulates expression of multiple ABC transporters and increases the EC50 of melanoma drug vemurafenib. Also, vemurafenib-resistant melanoma cells had upregulated levels of GH receptor (GHR) expression as well as ABC efflux pumps. GHR knockdown (KD) using siRNA in human melanoma cells treated with sub-EC50 doses of anti-tumor compounds resulted in significantly increased drug retention, decreased cell proliferation and increased drug efficacy, compared to mock-transfected controls. Our set of findings identify an unknown mechanism of GH regulation in mediating melanoma drug resistance and validates GHR as a unique therapeutic target for sensitizing highly therapy-resistant human melanoma cells to lower doses of anti-cancer drugs.

Advances in immunotherapy for melanoma management

Melanoma remains a leading cause of death among young adults. Evidence that melanoma tumor cells are highly immunogenic and a better understanding of T-cell immune checkpoints have changed the therapeutic approach to advanced melanoma. Instead of targeting the tumor directly, immunotherapy targets and activates the immune response using checkpoint inhibitors, monoclonal antibodies, vaccines, and adoptive T cell therapy. This review focuses on the immune signaling and biological mechanisms of action of recent immune-based melanoma therapies as well as their clinical benefits.

Nanomaterial-Based Vaccine Adjuvants

Vaccination is a biological process that administrates antigenic materials to stimulate an individual's immune system to develop immunity to a specific pathogen. It is the most effective tool to prevent illness and death from infectious diseases or diseases leading to cancers. Because many recombinant and synthetic antigens are poorly immunogenic, adjuvant is essentially added to vaccine formula that can potentiate the immune responses, offer better protection against pathogens and reduce the amount of antigens needed for protective immunity. To date, there are nearly 100 different types of adjuvants associated with about 400 vaccines that are either commercially available or under development. Among these adjuvants, many of them are particulates and nano-scale in nature. Nanoparticles represent a wide range of materials with novel physicochemical properties that exhibit immunostimulatory effects. However, the mechanistic understandings on how their physicochemical properties affect immunopotentiation remain elusive. In this article, we aim to review current development status of nanomaterial-based vaccine adjuvants, and further discuss their acting mechanisms, understanding of which will benefit the rational design of effective vaccine adjuvants with improved immunogenicity for prevention of infectious disease as well as therapeutic cancer treatment.

The dual role of NK cells in antitumor reactions triggered by ionizing radiation in combination with hyperthermia

Classical tumor therapy consists of surgery, radio(RT)- and/or chemotherapy. Additive immunotherapy has gained in impact and antitumor in situ immunization strategies are promising to strengthen innate and adaptive immune responses. Immunological effects of RT and especially in combination with immune stimulation are mostly described for melanoma. Since hyperthermia (HT) in multimodal settings is capable of rendering tumor cells immunogenic, we analyzed the in vivo immunogenic potential of RT plus HT-treated B16 melanoma cells with an immunization and therapeutic assay. We focused on the role of natural killer (NK) cells in the triggered antitumor reactions. In vitro experiments showed that RT plus HT-treated B16 melanoma cells died via apoptosis and necrosis and released especially the danger signal HMGB1. The in vivo analyses revealed that melanoma cells are rendered immunogenic by RT plus HT. Especially, the repetitive immunization with treated melanoma cells led to an increase in NK cell number in draining lymph nodes, particularly of the immune regulatory CD27⁺CD11b⁻ NK cell subpopulation. While permanent NK cell depletion after immunization led to a significant acceleration of tumor outgrowth, a single NK cell depletion two days before immunization resulted in significant tumor growth retardation. The therapeutic model, a local in situ immunization closely resembling the clinical situation when solid tumors are exposed locally to RT plus HT, confirmed these effects. We conclude that a dual and time-dependent impact of NK cells on the efficacy of antitumor immune reactions induced by immunogenic tumor cells generated with RT plus HT exists.

Immuno-oncology combinations: raising the tail of the survival curve

There have been exponential gains in immuno-oncology in recent times through the development of immune checkpoint inhibitors. Already approved by the U.S. Food and Drug Administration for advanced melanoma and non-small cell lung cancer, immune checkpoint inhibitors also appear to have significant antitumor activity in multiple other tumor types. An exciting component of immunotherapy is the durability of antitumor responses observed, with some patients achieving disease control for many years. Nevertheless, not all patients benefit, and efforts should thus now focus on improving the efficacy of immunotherapy through the use of combination approaches and predictive biomarkers of response and resistance. There are multiple potential rational combinations using an immunotherapy backbone, including existing treatments such as radiotherapy, chemotherapy or molecularly targeted agents, as well as other immunotherapeutics. The aim of such antitumor strategies will be to raise the tail on the survival curve by increasing the number of long term survivors, while managing any additive or synergistic toxicities that may arise with immunotherapy combinations. Rational trial designs based on a clear understanding of tumor biology and drug pharmacology remain paramount. This article reviews the biology underpinning immuno-oncology, discusses existing and novel immunotherapeutic combinations currently in development, the challenges of predictive biomarkers of response and resistance and the impact of immuno-oncology on early phase clinical trial design.

The role of active vaccination in cancer immunotherapy: lessons from clinical trials

In the past few years, a number of different immunotherapeutic strategies have shown impressive results in cancer patients. These successful approaches include blockade of immunosuppressive molecules like PD-1 and CTLA-4, adoptive transfer of patient derived and genetically modified T-cells, and vaccines that stimulate tumor antigen specific T-cells. However, several large vaccine trials recently failed to reach designated primary endpoints. In light of the success of other immunotherapeutic approaches, these negative results raise the questions of why vaccines have not generated a better response, and what the role of active vaccination will be moving forward in cancer immunotherapy.

Vaccines, Adjuvants, and Dendritic Cell Activators--Current Status and Future Challenges

Cancer vaccines offer a low-toxicity approach to induce anticancer immune responses. They have shown promise for clinical benefit with one cancer vaccine approved in the United States for advanced prostate cancer. As other immune therapies are now clearly effective for treatment of advanced cancers of many histologies, there is renewed enthusiasm for optimizing cancer vaccines for use to prevent recurrence in early-stage cancers and/or to combine with other immune therapies for therapy of advanced cancers. Future advancements in vaccine therapy will involve the identification and selection of effective antigen formulations, optimization of adjuvants, dendritic cell (DC) activation, and combination therapies. In this summary we present the current practice, the broad collection of challenges, and the promising future directions of vaccine therapy for cancer.

Particulate inorganic adjuvants: recent developments and future outlook

Objectives

To review the state of the art and assess future potential in the use of inorganic particulates as vaccine adjuvants.

Key findings

An adjuvant is an entity added to a vaccine formulation to ensure that robust immunity to the antigen is inculcated. The inclusion of an adjuvant is typically vital for the efficacy of vaccines using inactivated organisms, subunit and DNA antigens. With increasing research efforts being focused on subunit and DNA antigens because of their improved safety profiles, the development of appropriate adjuvants is becoming ever more crucial. Despite this, very few adjuvants are licensed for use in humans (four by the FDA, five by the European Medicines Agency). The most widely used adjuvant, alum, has been used for nearly 90 years, yet its mechanism of action remains poorly understood. In addition, while alum produces a powerful antibody Th2 response, it does not provoke the cellular immune response required for the elimination of intracellular infections or cancers. New adjuvants are therefore needed, and inorganic systems have attracted much attention in this regard.

Summary

In this review, the inorganic adjuvants currently in use are considered, and the efforts made to date to understand their mechanisms of action are summarised. We then move on to survey the literature on inorganic particulate adjuvants, focusing on the most interesting recent developments in this area and their future potential.