Melanoma is the most lethal form of skin cancer and surgery remains the preferred and most effective treatment. Nevertheless, there are cases where surgery is not a viable method and alternative treatments are therefore adopted. One such treatment that has been tested is topical 5% imiquimod (IMQ) cream, which, although showing promise as a treatment for melanoma, has been found to have undesirable off-target effects. Resiquimod (RSQ) is an immunomodulatory molecule that can activate immune responses by binding to Toll-like receptors (TLR) 7 and 8 and may be more effective than IMQ in the context of melanoma treatment. RSQ can cross the stratum corneum (SC) easily without requiring pretreatment of the skin. In a gel formulation, RSQ has been studied as a monotherapy and adjuvant for melanoma treatment in pre-clinical studies and as an adjuvant in clinical settings. Although side effects of RSQ in gel formulation were also reported, they were never severe enough for the treatment to be suspended. In this review, we discuss the potential use of RSQ as an adjuvant for melanoma treatment.

Salak peel extract has various biological properties befitting cosmeceutical applications; however, their practical uses are still limited due to their low water solubility and stability. Encapsulation technology was employed to alleviate these issues. In this work, we presented a simple method to prepare ethosome-encapsulated salak peel extract using green solvents (ethanol and water). For this purpose, we used 95% ethanol to extract salak peel and explored its activities. Results showed that, in addition to anti-oxidant, the extract also showed anti-tyrosinase, anti-inflammatory, and anti-bacterial (against S. aureus) activities. These activities indicate its potential uses in cosmeceutical applications. We further encapsulated the extract in ethosomes using a stirrer and green solvents for the preparation methods. The yielded ethosomes exhibited a size range of 120 to 205 nm, polydispersity index (PDI) of 0.15 to 0.25, and zeta potential of −35 to −60 mV depending on the amount of L-α-phosphatidylcholine used. The highest encapsulation efficiency was approximately 30%. The antiradical capacity and anti-inflammatory activities of salak peel extract were also found to be maintained after the encapsulation process. An in vitro biocompatibility study of the extract after encapsulation was also performed. The results not only indicated good biocompatibility, but also the potential skin-rejuvenating ability of salak peel ethosomes. A stability study was also performed, and the results suggested that these ethosomes were stable at different conditions. With further investigation, salak peel ethosomes, as presented here, can be suitable for cosmeceutical applications.

Melanoma is responsible for most skin cancer-related deaths, despite accounting for only 1% of all skin cancer cases. At present, surgery is considered the most promising treatment as it can effectively cure stage 0 and stage I melanoma patients. However, there are cases where surgery cannot be implemented or ineffective. Various alternative treatments for melanoma are available and among them, immunotherapy emerges as the most promising. Nevertheless, immunotherapy efficacy can still be limited, especially when a single agent is used. Melanoma can have multiple cell death resistance mechanisms. Thus, combination treatments that target more than one mechanism at the same time can have more promising results as suggested by increasing evidence. Resiquimod (RSQ), an imidazoquinolinamine derivative and Toll-like receptor-7/8 (TLR-7/8) agonist, is a promising candidate for melanoma treatment, as indicated by both pre-clinical and clinical studies. In this dissertation, we explored two relatively new combinations for melanoma treatment based on RSQ: RSQ+anti-PD-1 (immune checkpoint blockade), and RSQ+silver nanoparticles (AgNP).The first part of the research explored the in vitro effects of RSQ and then the in vivo effect of the combination of RSQ and anti-PD-1 on the survival of melanoma-challenged mice. Anti-PD-1, an immune checkpoint inhibitor, works by preventing the interaction between PD-1 on immune cells (specifically activated T cells) and PDL-1 on melanoma cells, can be an effective melanoma treatment. However, the percentage of melanoma patients that benefit from anti-PD-1 monotherapy is low, and a hostile immunosuppressive tumor microenvironment (TME) may be at least partly responsible. RSQ could potentially enhance the antitumor activity of immune checkpoint blockade when these agents are combined as a treatment for melanoma. In this study, the effect of combining systemic anti-PD-1 and locally administered RSQ on the survival of melanoma-challenged mice was tested. Our results demonstrated that anti-PD-1 in combination with RSQ can significantly prolong the survival of melanoma-challenged mice, compared to untreated mice and mice treated with anti-PD-1 alone. In addition, the in vitro effect of RSQ on B16.F10 melanoma cells was also investigated. The results showed that RSQ had a direct anti-proliferative effect on melanoma cells and induced IL-12 production from melanoma cells. These direct effects of RSQ on melanoma cells may potentially explain the enhanced anti-melanoma effects of RSQ in vivo. Toxicity analysis was also performed based on the analysis of mice sera from treated mice. The results showed that all the treatments, including the RSQ+anti-PD-1 combination, appeared to be safe in mice. In conclusion, the combination of RSQ and anti-PD-1 may be a promising treatment for melanoma patients, especially as both treatments have independently already been used to treat melanoma patients. The second part of the research investigated the in vitro effect of AgNP and the in vivo effect of RSQ and AgNP combination on the survival of melanoma-challenged mice. Over the last decade, the potential for 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 and 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 RSQ was investigated and shown to significantly prolong the survival of melanoma-challenged mice compared to untreated mice, while either agent alone did not. Toxicity analysis was also conducted and the results showed that all the treatments, RSQ+AgNP included, seemed to be safe in mice. Immune cell depletion studies could not implicate a statistically significant involvement of the adaptive immune response in the antitumor response observed from the AgNP+RSQ treatment. In conclusion, the combination of AgNP and RSQ is a new combination worthy of further investigation in the context of melanoma treatment. In summary, the combinations of RSQ+anti-PD-1 and RSQ+AgNP exhibited higher anti-melanoma treatment efficacy than their monotherapy counterparts. Their toxicity profile also indicated their safety, at least in mice. Hence, both combinations emerge as potential candidates for melanoma treatment.