Oral Pre-malignancy: An Update on Novel Therapeutic Approaches

PURPOSE OF REVIEW

This review aims to provide a comprehensive overview of the current advances in managing and preventing progression of oral potentially malignant disorders (OPMDs), focusing on their histological and clinicopathological features, and management.

RECENT FINDINGS

Recent studies, including a multicenter cross-sectional study, have identified oral leukoplakia as the most prevalent form of OPMD, comprising over half of the cases examined. Advances in histological grading, specifically the World Health Organization's three-tier system (mild, moderate, and severe dysplasia), have significantly enhanced the accuracy of risk assessment for malignant transformation. Additionally, treatments such as surgical interventions, photodynamic therapy, and chemopreventive and molecularly targeted agents are being evaluated for their safety and efficacy as well as, immune checkpoint inhibitors being evaluated as potential preventive strategies to halt the progression of OPMDs. The management of OPMDs remains challenging due to the lack of standardized screening protocols and varied clinical management approaches. Despite this, recent advancements in diagnostic grading and therapeutic interventions provide a framework for improved treatment outcomes. Continued research into the molecular and cellular mechanisms driving development and progression of OPMDs and innovative treatment trials are essential to optimize strategies that prevent malignant progression and thereby reduce the global health burden of oral cancer.

Current Role and Status for Intratumoral Injection Therapies in Metastatic Melanoma

ABSTRACT

Intratumoral therapies represent a unique avenue for drug development in melanoma as patients often have accessible lesions that are particularly amenable to these approaches. In addition, a majority of intratumoral therapies have focused on stimulating antitumor immune responses, making them a particularly attractive option for use in melanoma. In this review, we describe applications for talimogene laherparepvec, a US Food and Drug Administration-approved intratumoral therapy in melanoma, as well as several classes of intratumoral therapies in development including novel oncolytic viruses, mRNA-based intratumoral injections, and cytokines and other signaling molecules.

Intratumoral therapies and in-situ vaccination for melanoma

Skin cancers are among the most physically accessible malignancies, so local delivery of a medication into the tumor, so-called intratumoral therapy, is an appealing route of drug administration. Intratumoral therapies have the potential to increase local drug concentration and/or attract immune cells to the local tumor microenvironment, possibly with fewer systemic side effects. A wide array of intratumoral agents have been studied to date in patients with advanced melanoma, including chemotherapeutic drugs, immune modulating agents, and cancer-directed vaccines. In this review, we will summarize the key pre-clinical and clinical data supporting the use of intratumoral therapy for advanced unresectable and metastatic melanoma. First, we will discuss the history of intratumoral immunotherapy for the treatment of melanoma and the various agents studied to date. Second, we will explore how intratumoral therapies can constitute an in situ vaccine, potentially leading to disease control both locally and systemically. Finally, we will highlight opportunities in the field and key future directions.

Intratumoural immunotherapies for unresectable and metastatic melanoma: current status and future perspectives

The emergence of human intratumoural immunotherapy (HIT-IT) is a major step forward in the management of unresectable melanoma. The direct injection of treatments into melanoma lesions can cause cell lysis and induce a local immune response, and might be associated with a systemic immune response. Directly injecting immunotherapies into tumours achieves a high local concentration of immunostimulatory agent while minimising systemic exposure and, as such, HIT-IT agents are associated with lower toxicity than systemic immune checkpoint inhibitors (CPIs), enabling their potential use in combination with other therapies. Consequently, multiple HIT-IT agents, including oncolytic viruses, pattern-recognition receptor agonists, injected CPIs, cytokines and immune glycolipids, are under investigation. This review considers the current clinical development status of HIT-IT agents as monotherapy and in combination with systemic CPIs, and the practical aspects of administering and assessing the response to these agents. The future of HIT-IT probably lies in its use in combination with systemic CPIs; data from Phase 2 trials indicate a synergy between HIT-IT and CPIs. Data also suggest that the addition of HIT-IT to a CPI might generate responses in CPI-refractory tumours, thereby overcoming resistance and addressing a current unmet need in unresectable and metastatic melanoma for treatment options following progression after CPI treatment.

Intratumoral and Combination Therapy in Melanoma and Other Skin Cancers

Skin cancer, as the most physically accessible malignancy, allows for the greatest variety in treatment innovation. The last 2 decades have seen striking increases in the life expectancies of those diagnosed with malignant melanoma. However, many cases remain in which disease prevails against standard treatment, and those patients rely on continuing ingenuity. Drugs that can be injected directly into patients' tumors have become increasingly promising, not least for the reduction in side effects observed. Intratumoral therapy encompasses a wide array of agents, from chemotherapeutic drugs to cancer vaccines. While each show some efficacy, those agents which regulate the immune system likely have the greatest potential for preventing disease progression or recurrence. Recent research has highlighted the importance of the presence of cytotoxic T cells and of keeping regulatory T cells in check. Thus, manipulating the tumor microenvironment is a need in skin cancer therapy, which intratumoral delivery can potentially address. In order to find the best approach to each person's disease, more studies are needed to test intralesional agents in combination with currently approved therapies and with each other.

Programmed cell death 1 protein and programmed death-ligand 1 inhibitors in the treatment of nonmelanoma skin cancer: A systematic review

BACKGROUND

Immunotherapy using programmed cell death 1 protein (PD-1) or programmed death-ligand 1 (PD-L1) inhibitors has been increasingly reported in a variety of nonmelanoma skin cancers (NMSCs).

OBJECTIVE

To analyze the evidence of PD-1 and PD-L1 inhibitors in the treatment of NMSC.

METHODS

A primary literature search was conducted with the PubMed, Cochrane Library, EMBASE, Web of Science, and CINAHL databases through October 28, 2018, to include studies on the use of PD-1 or PD-L1 inhibitors in patients for NMSC. Two reviewers independently performed study selection, data extraction, and critical appraisal.

RESULTS

This systematic review included 51 articles. The most robust evidence was in the treatment of Merkel cell carcinoma and cutaneous squamous cell carcinomas, as supported by phase 1 and 2 clinical trials. Treatment of basal cell carcinoma, cutaneous sarcoma, sebaceous carcinoma, and malignant peripheral nerve sheath tumor also showed benefit with PD-1/PD-L1 inhibitors, but data are limited. There does not appear to be efficacy for PD-1/PD-L1 inhibitors in cutaneous lymphomas.

LIMITATIONS

More investigation is needed to determine the efficacy, tumor responsiveness, and the safety profile of PD-1 and PD-L1 inhibitors in NMSC.

CONCLUSION

PD-1 and PD-L1 inhibitors exhibit treatment efficacy in a variety of NMSCs.

Recent advances in localized immunotherapy of skin cancers

Skin cancer is the most frequent malignancy in humans. The immune system has long been known to have an important role in defeating cancer. Immunotherapy, which includes various strategies to enhance tumor immunity, currently represents an exciting option for the treatment of skin cancers. Local immunotherapy is a promising therapeutic approach and may improve response rates without inducing systemic toxicity. Here, we review the main localized immunotherapies for the management of skin cancer with a special focus on advanced melanoma, nonmelanoma skin cancer and primary cutaneous lymphoma.