Topically Applied Resiquimod versus Imiquimod as a Potential Adjuvant in Melanoma Treatment

Soluble-microneedle enhance three T-cell activation signals as efficient tumor vaccines for melanoma prevention and treatment

Therapeutic tumor vaccines, which activate self-T cells to eliminate tumors, hold tremendous promise in future cancer immunotherapy with high specificity and low side effects. To effectively activate T cell, dendritic cells (DCs) need simultaneously provide three indispensable signals to naive T cells, including MHC-antigen signal, costimulation signal and cytokine stimulation. However, current marketed therapeutic tumor vaccines still suffer from lacking the ability to activate three stimulation signals at the same time, which resulted to the low response rate and unsatisfied therapeutic efficiency. Here, we proposed a soluble microneedle-based tumor vaccines (TR-12@LGMN) which facilitate triple activation of antigen presentation and induce high immune response rate. First, the melanoma-specific antigen tyrosinaserelated protein-2 (Trp2), Resiquimod (R848), and IL-12 mRNA co-loaded liposomes (TR-12@LIPO) was prepared. The TR-12@LIPO ensured triple-activating three essential signals of antigen presentation through enhancing the binding of MHC I-antigen peptides to T cell receptor (TCR), the binding of CD80/86 on DCs to CD28 on T cells, and the release of cytokines for T cells activation. Second, TR-12@LIPO was co-dispersed in polyvinylpyrrolidone-polyvinyl alcohol (PVP-PVA) matrix with granulocyte-macrophage colony stimulating factor (GM-CSF) to prepare TR-12@LGMN by mold method. The TR-12@LGMN was quadrilateral shape with sufficient mechanical strength for skin piercing. After skin insertion, TR-12@LGMN dissolved in the skin interstitial fluid to release GM-CSF and TR-12@LIPO. DCs were recruited by GM-CSF and uptaked TR-12@LIPO. TR-12@LIPO showed enhancement of cross-presentation by antigen cytoplasmic delivery, DCs maturation and IL-12 secretion. In vivo results showed that TR-12@LGMN could efficiently activate CD8+ T cells, induce antigen-specific cytotoxic T cells (CTLs) and memory T cell (Tm). Ultimately, strong anti-tumor immunity and long-term durable tumor control were achieved in the B16F10 tumor prevention and treatment model. Overall, our work proposes a triple-activated antigen presentation strategy and designs a microneedle-based tumor vaccine for skin delivery, revealing a potential promising direction for the development of new therapeutic tumor vaccines methods.

Rational design of adjuvants boosts cancer vaccines

Cancer vaccines are expected to be next breakthrough in cancer immunotherapy. In cancer vaccines, adjuvants play an important role by enhancing and reshaping tumor antigen-specific immune responses. Failures in previous cancer vaccine clinical trials can be attributed to inappropriate selection and design of tumor antigens and adjuvants. Using basic theories of tumor immunology, the development of sequencing technology and nanotechnology enables the creation of cancer vaccines through appropriate selection of tumor antigens and adjuvants and their nanoscale assembly based on the specific characteristics of each tumor. In this chapter, we begin by discussing the various types of cancer vaccines and categories of tumor antigens. Then, we summarize the classification of adjuvants for cancer vaccines, including immunostimulatory molecules and delivery systems, and clarify the various factors that influence the properties of adjuvants, such as chemical composition, structure, and surface modification. Finally, we provide perspectives and insights on rational design of adjuvants in cancer vaccines to enhance their efficacy.

The role of dendritic cells in cancer immunity and therapeutic strategies

Dendritic cells (DCs) are asserted as the most potent antigen-presenting cells (APCs) that orchestrate both innate and adaptive immunity, being extremely effective in the induction of robust anti-cancer T cell responses. Hence, the modulation of DCs function represents an attractive target for improving cancer immunotherapy efficacy. A better understanding of the immunobiology of DCs, the interaction among DCs, immune effector cells and tumor cells in tumor microenvironment (TME) and the latest advances in biomedical engineering technology would be required for the design of optimal DC-based immunotherapy. In this review, we focus on elaborating the immunobiology of DCs in healthy and cancer environments, the recent advances in the development of enhancing endogenous DCs immunocompetence via immunomodulators as well as DC-based vaccines. The rapidly developing field of applying nanotechnology to improve DC-based immunotherapy is also highlighted.

The scientific journey of a novel adjuvant (AS37) from bench to bedside

A decade ago, we described a new approach to discover next generation adjuvants, identifying small-molecule immune potentiators (SMIPs) as Toll-like receptor (TLR)7 agonists. We also optimally formulated these drugs through adsorption to aluminum salts (alum), allowing them to be evaluated with a range of established and early-stage vaccines. Early proof-of-concept studies showed that a TLR7 agonist (TLR7a)-based SMIP, when adsorbed to alum, could perform as an effective adjuvant for a variety of different antigens, in both small and large animals. Studies in rodents demonstrated that the adjuvant enhanced immunogenicity of a recombinant protein-based vaccine against Staphylococcus aureus, and also showed potential to improve existing vaccines against pertussis or meningococcal infection. Extensive evaluations showed that the adjuvant was effective in non-human primates (NHPs), exploiting a mechanism of action that was consistent across the different animal models. The adjuvant formulation (named AS37) has now been advanced into clinical evaluation. A systems biology-based evaluation of the phase I clinical data with a meningococcal C conjugate vaccine showed that the AS37-adjuvanted formulation had an acceptable safety profile, was potent, and activated the expected immune pathways in humans, which was consistent with observations from the NHP studies. In the intervening decade, several alternative TLR7 agonists have also emerged and advanced into clinical development, such as the alum adsorbed TLR7/8 SMIP present in a widely distributed COVID-19 vaccine. This review summarizes the research and early development of the new adjuvant AS37, with an emphasis on the steps taken to allow its progression into clinical evaluations.

Cutaneous Oncology: Strategies for Melanoma Prevention, Diagnosis, and Therapy

Skin cancer comprises one-third of all diagnosed cancer cases and remains a major health concern. Genetic and environmental parameters serve as the two main risk factors associated with the development of skin cancer, with ultraviolet radiation being the most common environmental risk factor. Studies have also found fair complexion, arsenic toxicity, indoor tanning, and family history among the prevailing causes of skin cancer. Prevention and early diagnosis play a crucial role in reducing the frequency and ensuring effective management of skin cancer. Recent studies have focused on exploring minimally invasive or non-invasive diagnostic technologies along with artificial intelligence to facilitate rapid and accurate diagnosis. The treatment of skin cancer ranges from traditional surgical excision to various advanced methods such as phototherapy, radiotherapy, immunotherapy, targeted therapy, and combination therapy. Recent studies have focused on immunotherapy, with the introduction of new checkpoint inhibitors and personalized immunotherapy enhancing treatment efficacy. Advancements in multi-omics, nanotechnology, and artificial intelligence have further deepened the understanding of the mechanisms underlying tumoral growth and their interaction with therapeutic effects, which has paved the way for precision oncology. This review aims to highlight the recent advancements in the understanding and management of skin cancer, and provide an overview of existing and emerging diagnostic, prognostic, and therapeutic modalities, while highlighting areas that require further research to bridge the existing knowledge gaps.

Chromoblastomycosis: New Perspective on Adjuvant Treatment with Acitretin

Chromoblastomycosis (CBM) is a neglected human disease, caused by different species of pigmented dematiaceous fungi that cause granulomatous and suppurative dermatosis. This infection is difficult to treat and there are limited therapeutic options, including terbinafine, itraconazole, and tioconazole. Classic treatment is administered for a long period of time, but some patients do not respond properly, and therefore, such therapeutic approaches possess low cure rates. Therefore, it is vital to develop new strategies for the treatment of CBM. In this regard, it has been observed that the association of immunomodulatory molecules such as glucan with therapy carried out with antifungal drugs improves cutaneous lesions in comparison to treatment with antifungal drugs alone, suggesting that drug association may be an interesting and significant approach to incorporate into CBM therapy. Thus, the aim of this work was to associate classical antifungal therapy with the adjuvants imiquimod and acitretin. In the present case, we reported a patient with extensive CBM caused by Fonsaecae pedrosoi, that affected an extensive area of the right leg, that was left without treatment for 11 years. He was treated with a classical combination of itraconazole and terbinafine via the oral route plus topical imiquimod and oral acitretin, as an adjuvant therapy. After five months of treatment, a significant regression of verrucous plaques was observed, suggesting that the use of these adjuvants combined with the classical antifungal drugs, intraconazole plus terbinafine, can reduce treatment time and rapidly improve the patient's quality of life. This result confirms that the use of coadjuvant drugs may be effective in the treatment of this infectious disease.

Progress towards Adjuvant Development: Focus on Antiviral Therapy

In recent decades, vaccines have been extraordinary resources to prevent pathogen diffusion and cancer. Even if they can be formed by a single antigen, the addition of one or more adjuvants represents the key to enhance the response of the immune signal to the antigen, thus accelerating and increasing the duration and the potency of the protective effect. Their use is of particular importance for vulnerable populations, such as the elderly or immunocompromised people. Despite their importance, only in the last forty years has the search for novel adjuvants increased, with the discovery of novel classes of immune potentiators and immunomodulators. Due to the complexity of the cascades involved in immune signal activation, their mechanism of action remains poorly understood, even if significant discovery has been recently made thanks to recombinant technology and metabolomics. This review focuses on the classes of adjuvants under research, recent mechanism of action studies, as well as nanodelivery systems and novel classes of adjuvants that can be chemically manipulated to create novel small molecule adjuvants.

Investigating silver nanoparticles and resiquimod as a local melanoma treatment

Over the last decade, the potential for silver nanoparticles (AgNP) to be used as an anti-melanoma agent has been supported by both in vitro and in vivo evidence. However, an undesirably high concentration of AgNP is often required to achieve an antitumor effect. Therefore a combination treatment that can maintain or improve antitumor efficacy (with lower amounts of AgNP) while also reducing off-target effects is sought. In this study, the combination of AgNP and resiquimod (RSQ: a Toll-like receptor agonist) was investigated and shown to significantly prolong the survival of melanoma-challenged mice when added sequentially. Results from toxicity studies showed that the treatment was non-toxic in mice. Immune cell depletion studies suggested the possible involvement of CD8+ T cells in the antitumor response observed in the AgNP + RSQ (sequential) treatment. NanoString was also employed to further understand the mechanism underlying the increase in the treatment efficacy of AgNP + RSQ (sequential); showing significant changes, compared to the naive group, in gene expression in pathways involved in apoptosis and immune stimulation. In conclusion, the combination of AgNP and RSQ is a new combination worthy of further investigation in the context of melanoma treatment.

Peptide Vaccines in Melanoma: Chemical Approaches towards Improved Immunotherapeutic Efficacy

Cancer of the skin is by far the most common of all cancers. Although the incidence of melanoma is relatively low among skin cancers, it can account for a high number of skin cancer deaths. Since the start of deeper insight into the mechanisms of melanoma tumorigenesis and their strong interaction with the immune system, the development of new therapeutical strategies has been continuously rising. The high number of melanoma cell mutations provides a diverse set of antigens that the immune system can recognize and use to distinguish tumor cells from normal cells. Peptide-based synthetic anti-tumor vaccines are based on tumor antigens that elicit an immune response due to antigen-presenting cells (APCs). Although targeting APCs with peptide antigens is the most important assumption for vaccine development, peptide antigens alone are poorly immunogenic. The immunogenicity of peptide antigens can be improved not only by synthetic modifications but also by the assistance of adjuvants and/or delivery systems. The current review summarizes the different chemical approaches for the development of effective peptide-based vaccines for the immunotherapeutic treatment of advanced melanoma.