Beyond PD-1: The Next Frontier for Immunotherapy in Melanoma

Harnessing the tumor microenvironment to boost adoptive T cell therapy with engineered lymphocytes for solid tumors

Adoptive cell therapy (ACT) using Chimeric Antigen Receptor (CAR) and T Cell Receptor (TCR) engineered T cells represents an innovative therapeutic approach for the treatment of hematological malignancies, yet its application for solid tumors is still suboptimal. The tumor microenvironment (TME) places several challenges to overcome for a satisfactory therapeutic effect, such as physical barriers (fibrotic capsule and stroma), and inhibitory signals impeding T cell function. Some of these obstacles can be faced by combining ACT with other anti-tumor approaches, such as chemo/radiotherapy and checkpoint inhibitors. On the other hand, cutting edge technological tools offer the opportunity to overcome and, in some cases, take advantage of TME intrinsic characteristics to boost ACT efficacy. These include: the exploitation of chemokine gradients and integrin expression for preferential T-cell homing and extravasation; metabolic changes that have direct or indirect effects on TCR-T and CAR-T cells by increasing antigen presentation and reshaping T cell phenotype; introduction of additional synthetic receptors on TCR-T and CAR-T cells with the aim of increasing T cells survival and fitness.

COLUMBUS-AD: phase III study of adjuvant encorafenib + binimetinib in resected stage IIB/IIC BRAF V600-mutated melanoma

Stage IIB/IIC melanoma has a high risk of recurrence after surgical resection. While, for decades, surgery was the only option for high-risk stage II disease in most countries, adjuvant therapies now exist. Anti-programmed cell death protein 1 (PD-1) antibodies significantly improve recurrence-free survival versus placebo in patients with fully resected stage IIB/IIC melanoma. Combined BRAF MEK inhibitor therapy showed benefits in high-risk stage III and advanced disease; however, its role in patients with fully resected stage BRAF-mutated IIB/IIC melanoma is still unknown. Here we describe the rationale and design of the ongoing randomized, placebo-controlled COLUMBUS-AD trial, the first study of a BRAF-MEK inhibitor combination therapy (encorafenib + binimetinib) in patients with BRAF V600-mutated stage IIB/IIC melanoma.

The Current State of Neoadjuvant Therapy in Resectable Advanced Stage Melanoma

The advent of effective immunotherapy and targeted therapy has significantly improved outcomes in advanced-stage resectable melanoma. Currently, the mainstay of treatment of malignant melanoma is surgery followed by adjuvant systemic therapies. However, recent studies have shown a potential role for neoadjuvant therapy in the treatment of advanced-stage resectable melanoma. Mechanistically, neoadjuvant immunotherapy may yield a more robust response than adjuvant immunotherapy, as the primary tumor serves as an antigen in this setting rather than only micrometastatic disease after the index procedure. Additionally, targeted therapy has been shown to yield effective neoadjuvant cytoreduction, and oncolytic viruses may also increase the immunogenicity of primary tumors. Effective neoadjuvant therapy may serve to decrease tumor size and thus reduce the extent of required surgery and thus morbidity. It also allows for assessment of pathologic response, facilitating prognostication as well as tailoring future therapy. The current literature consistently supports that neoadjuvant therapy, even as little as one dose, is associated with improved outcomes and is well-tolerated. Some patients with a complete pathological response may even avoid surgery completely. These results challenge the current paradigm of a surgery-first approach and provide further evidence supporting neoadjuvant therapy in advanced-stage resectable melanoma. Further research into the optimal treatment schedule and dose timing is warranted, as is the continued investigation of novel therapies and combinations of therapies.

Correlation of immune makers with HPV 16 infections and the prognosis in oropharyngeal squamous cell carcinoma

OBJECTIVES

This study aims to investigate the association of immune markers with high risk human papillomavirus 16 (HPV 16) infection status and to evaluate the prognostic value of programmed death ligand-1 (PD-L1) in patients with oropharyngeal squamous cell carcinoma (OPSCC).

MATERIALS AND METHODS

This retrospective study collected 50 cases of HPV positive and HPV negative OPSCC from January 2011 to December 2015. The correlation of CD8 + tumor infiltrating lymphocytes (TILs), programmed death-1 (PD-1), and PD-L1 expression with HPV 16 infection status was analyzed via immunofluorescent staining and quantitative real-time PCR.

RESULTS

There was no significant difference in the baseline data between the two groups. Patients with HPV + OPSCC had better prognosis compared to HPV - patients (5-year overall survival [OS], 66% vs. 40%, P = 0.003; 5-year disease specific survival [DSS], 73% vs. 44%, P = 0.001). The expressions of immunity related makers were significantly higher in the HPV + group than the HPV - group (CD8 + TIL: P = 0.039; PD-L1: P = 0.005; PD-1: P = 0.044). Positive CD8 + TIL and PD-L1 were independent factors for better prognosis of OPSCC (DSS, P < 0.001; OS, P < 0.001, respectively). Kaplan-Meier survival analysis indicated that patients with TILs of high HPV + /CD8 + expression were more likely to have better prognosis than those with TILs of low HPV + /CD8 + expression (DSS, P < 0.001; OS, P < 0.001), TILs of high expression of HPV - /CD8 + (DSS, P = 0.010; OS, P = 0.032), and TILs of low expression of HPV - /CD8 + (DSS, P < 0.001; OS, P < 0.001). Furthermore, HPV + /PD-L1 + OPSCC patients had significant better prognosis compared to patients with HPV + /PD-L1 - (DSS, P < 0.001; OS, P = 0.004), HPV - /PD-L1 + (DSS, P = 0.010; OS, P = 0.048) and HPV - /PD-L1 - (DSS, P < 0.001; OS, P < 0.001).

CONCLUSIONS

HPV + OPSCC had a significantly better prognosis, and PD-L1 expression was elevated in HPV + OPSCC. PD-L1 positivity might be related to the better prognosis of HPV + OPSCC.

CLINICAL RELEVANCE

This study provides a theoretical basis and baseline data for the application of immune checkpoint inhibitors in head and neck tumors.

The Roles of MiRNAs (MicroRNAs) in Melanoma Immunotherapy

Melanoma is the most aggressive form of skin cancer, characterized by life-threatening and rapidly spreading progression. Traditional targeted therapy can alleviate tumors by inactivating hyperactive kinases such as BRAF or MEK but inevitably encounters drug resistance. The advent of immunotherapy has revolutionized melanoma treatment and significantly improved the prognosis of melanoma patients. MicroRNAs (miRNAs) are intricately involved in innate and adaptive immunity and are implicated in melanoma immunotherapy. This systematic review describes the roles of miRNAs in regulating the functions of immune cells in skin and melanoma, as well as the involvement of miRNAs in pharmacology including the effect, resistance and immune-related adverse events of checkpoint inhibitors such as PD-1 and CTLA-4 inhibitors, which are used for treating cutaneous, uveal and mucosal melanoma. The expressions and functions of miRNAs in immunotherapy employing tumor-infiltrating lymphocytes and Toll-like receptor 9 agonists are also discussed. The prospect of innovative therapeutic strategies such as the combined administration of miRNAs and immune checkpoint inhibitors and the nanotechnology-based delivery of miRNAs are also provided. A comprehensive understanding of the interplay between miRNAs and immunotherapy is crucial for the discovery of reliable biomarkers and for the development of novel miRNA-based therapeutics against melanoma.

Immunomodulatory Properties of Immune Checkpoint Inhibitors-More than Boosting T-Cell Responses?

The approval of immune checkpoint inhibitors (ICI) that serve to enhance effector T-cell anti-tumor responses has strongly improved success rates in the treatment of metastatic melanoma and other tumor types. The currently approved ICI constitute monoclonal antibodies blocking cytotoxic T-lymphocyte-associated protein (CTLA)-4 and anti-programmed cell death (PD)-1. By this, the T-cell-inhibitory CTLA-4/CD80/86 and PD-1/PD-1L/2L signaling axes are inhibited. This leads to sustained effector T-cell activity and circumvents the immune evasion of tumor cells, which frequently upregulate PD-L1 expression and modulate immune checkpoint molecule expression on leukocytes. As a result, profound clinical responses are observed in 40-60% of metastatic melanoma patients. Despite the pivotal role of T effector cells for triggering anti-tumor immunity, mounting evidence indicates that ICI efficacy may also be attributable to other cell types than T effector cells. In particular, emerging research has shown that ICI also impacts innate immune cells, such as myeloid cells, natural killer cells and innate lymphoid cells, which may amplify tumoricidal functions beyond triggering T effector cells, and thus improves clinical efficacy. Effects of ICI on non-T cells may additionally explain, in part, the character and extent of adverse effects associated with treatment. Deeper knowledge of these effects is required to further develop ICI treatment in terms of responsiveness of patients to treatment, to overcome resistance to ICI and to alleviate adverse effects. In this review we give an overview into the currently known immunomodulatory effects of ICI treatment in immune cell types other than the T cell compartment.

Management of metastatic melanoma with new immunotherapy approaches beyond PD-1/CTLA-4 inhibitors

PURPOSE OF REVIEW

If we may cure metastatic melanoma patients thanks to immune checkpoint inhibitors (ICI), it is fair to say that around 2/3 of the patients present primary or secondary resistance to ICI. Therefore, progresses are needed and numerous new treatments are tested either alone or in combination with cytolytic T-lymphocyte-associated protein 4 (CTLA-4) or (PD)-1 blockade to overcome this resistance. In this review, we focused on new immunotherapeutic approaches studied in advanced melanoma previously treated by anti-PD-1 (Programmed cell Death 1 receptor) or anti-CTLA-4 antibodies.

RECENT FINDINGS

The different approaches have been classified based on 'the cancer immunity cycle'. These new strategies target either the T-cell priming and activation step, T-cell trafficking and tumor infiltration, or tumor antigen recognition by T-cell and tumor killing.

SUMMARY

Most of these novel strategies are based on mAbs targeting T-cell inhibitory or stimulatory coreceptors. The second main focus is based on modifying the tumor micro-environment. Combination strategies seem promising in few patients and suggest that a deeper understanding of the resistance in individual patients is mandatory to go further.

The Role of the Vitamin D Receptor in the Pathogenesis, Prognosis, and Treatment of Cutaneous Melanoma

Melanoma is the malignant transformation of melanocytes and represents the most lethal form of skin cancer. While early-stage melanoma localized to the skin can be cured with surgical excision, metastatic melanoma often requires a multi-pronged approach and even then can exhibit treatment resistance. Understanding the molecular mechanisms involved in the pathogenesis of melanoma could lead to novel diagnostic, prognostic, and therapeutic strategies to ultimately decrease morbidity and mortality. One emerging candidate that may have value as both a prognostic marker and in a therapeutic context is the vitamin D receptor (VDR). VDR is a nuclear steroid hormone receptor activated by 1,25 dihydroxy-vitamin D3 [calcitriol, 1,25(OH)₂D3]. While 1,25 dihydroxy-vitamin D3 is typically thought of in relation to calcium metabolism, it also plays an important role in cell proliferation, differentiation, programmed-cell death as well as photoprotection. This review discusses the role of VDR in the crosstalk between keratinocytes and melanocytes during melanomagenesis and summarizes the clinical data regarding VDR polymorphisms, VDR as a prognostic marker, and potential uses of vitamin D and its analogs as an adjuvant treatment for melanoma.

Molecular Mechanisms of Resistance to Immune Checkpoint Inhibitors in Melanoma Treatment: An Update

Over the past decade, immune checkpoint inhibitors (ICI) have revolutionized the treatment of advanced melanoma and ensured significant improvement in overall survival versus chemotherapy. ICI or targeted therapy are now the first line treatment in advanced melanoma, depending on the tumor v-raf murine sarcoma viral oncogene homolog B1 (BRAF) mutational status. While these new approaches have changed the outcomes for many patients, a significant proportion of them still experience lack of response, known as primary resistance. Mechanisms of primary drug resistance are not fully elucidated. However, many alterations have been found in ICI-resistant melanomas and possibly contribute to that outcome. Furthermore, some tumors which initially responded to ICI treatment ultimately developed mechanisms of acquired resistance and subsequent tumor progression. In this review, we give an overview of tumor primary and acquired resistance mechanisms to ICI and discuss future perspectives with regards to new molecular targets and combinatorial therapies.

Durvalumab Plus Tremelimumab in Solid Tumors: A Systematic Review

INTRODUCTION

Cancer immunotherapy represents one of the most important innovations in modern medicine. Durvalumab is an anti-programmed cell death ligand 1 (PDL-1) agent which is currently under investigation in several studies in combination with the anti-cytotoxic T lymphocyte-associated protein 4 (CTLA-4) drug tremelimumab. The aim of this review was to systematically identify and revise the current scientific literature investigating the combination of these two drugs in solid tumors.

METHODS

A digital search on the Medline (PubMed interface) and Scopus databases for articles published from inception to 26 February 2021 was performed. The terms used for the search were durvalumab AND tremelimumab. Trials reported in English involving adult patients with solid cancers treated with the combination durvalumab plus tremelimumab were retrieved; the references of the articles were cross-checked to identify missing papers.

RESULTS

The electronic search produced 267 results; after exclusion of duplicates, irrelevant articles, reviews, and papers not in English or missing data, 19 articles were included for revision. The total number of patients treated with the combination of durvalumab and tremelimumab in the studies retrieved was 2052.

CONCLUSION

The combination of durvalumab plus tremelimumab showed some oncological advantages in comparison with traditional chemotherapies in some subsets of tumors, but generally has not shown consistent advantages in comparison with the employment of durvalumab monotherapy. A number of the studies examined had intrinsic methodological limitations; therefore, future well-designed studies involving larger cohorts are warranted.

Targeting Melanoma-Initiating Cells by Caffeine: In Silico and In Vitro Approaches

The beneficial effects of coffee on human diseases are well documented, but the molecular mechanisms of its bioactive compounds on cancer are not completely elucidated. This is likely due to the large heterogeneity of coffee preparations and different coffee-based beverages, but also to the choice of experimental models where proliferation, differentiation and immune responses are differently affected. The aim of the present study was to investigate the effects of one of the most interesting bioactive compounds in coffee, i.e., caffeine, using a cellular model of melanoma at a defined differentiation level. A preliminary in silico analysis carried out on public gene-expression databases identified genes potentially involved in caffeine’s effects and suggested some specific molecular targets, including tyrosinase. Proliferation was investigated in vitro on human melanoma initiating cells (MICs) and cytokine expression was measured in conditioned media. Tyrosinase was revealed as a key player in caffeine’s mechanisms of action, suggesting a crucial role in immunomodulation through the reduction in IL-1β, IP-10, MIP-1α, MIP-1β and RANTES secretion onto MICs conditioned media. The potent antiproliferative effects of caffeine on MICs are likely to occur by promoting melanin production and reducing inflammatory signals’ secretion. These data suggest tyrosinase as a key player mediating the effects of caffeine on melanoma.