Anti-programmed death receptor 1 immunotherapy in melanoma: rationale, evidence and clinical potential

Comparative Review of Malignant Melanoma and Histologically Well-Differentiated Melanocytic Neoplasm in the Oral Cavity of Dogs

Oral malignant melanoma (OMM) is the most common neoplasm of the canine oral cavity. It is characterized by its aggressive local disease as well as its high rate of lymphatic invasion and distant metastasis. OMM carries a poor prognosis, with most patients succumbing to the disease due to progression of the neoplasm. Histopathologically, OMM is characterized by significant nuclear atypia, a mitotic index of greater than 4/10 hpf, and evidence of vascular invasion or metastasis. Clinically, these lesions can become locally invasive, causing lysis of bones and severe inflammation of the surrounding soft tissue. With time, these lesions can spread to the regional lymph node and to the lungs and other organs. Prognosis can vary depending on the size of the primary tumor, regional node involvement, and distant metastatic disease; however, multiple studies report a relatively short median survival time ranging from less than 4 months to 8 months. Histologically well- differentiated melanocytic neoplasms (HWDMN) are a variant of OMM and sometimes referred to as canine oral melanocytic neoplasms of low malignant potential. Unlike OMM, patients with HWDMN have longer survival times. Histopathologically, HWDMNs have well-differentiated melanocytes with a low mitotic index of 3 or less per 10 hpf and minimal nuclear atypia. HWDMNs have better prognosis with a mean survival time of up to 34 months. This article is a comparative review of OMM and its less aggressive counterpart.

The Pattern of Time to Onset and Resolution of Immune-Related Adverse Events Caused by Immune Checkpoint Inhibitors in Cancer: A Pooled Analysis of 23 Clinical Trials and 8,436 Patients

PURPOSE

The occurrence pattern of immune-related adverse events (irAEs) induced by immune checkpoint inhibitor (ICI) in cancer treatment remains unclear.

Materials and Methods

Phase II-III clinical trials that evaluated ICI-based treatments in cancer and were published between January 2007 and December 2019 were retrieved from public electronic databases. The pooled median time to onset (PMT-O), resolution (PMT-R), and immune-modulation resolution (PMT-IMR) of irAEs were generated using the metamedian package of R software.

RESULTS

Twenty-two eligible studies involving 23 clinical trials and 8,436 patients were included. The PMT-O of all-grade irAEs ranged from 2.2 to 14.8 weeks, with the longest in renal events. The PMT-O of grade ≥ 3 irAEs was significantly longer than that of all-grade irAEs induced by programmed cell death protein 1 (PD-1) and its ligand 1 (PD-L1) inhibitors (27.5 weeks vs. 8.4 weeks, p < 0.001) and treatment of nivolumab (NIV) plus ipilimumab (IPI) (7.9 weeks vs. 6.0 weeks, p < 0.001). The PMT-R of all-grade irAEs ranged from 0.1 to 54.3 weeks, with the shortest and longest in hypersensitivity/infusion reaction and endocrine events, respectively. The PMT-IMR of grade ≥ 3 irAEs was significantly shorter than that of all-grade irAEs caused by PD-1/PD-L1 blockade (6.9 weeks vs. 40.6 weeks, p=0.002) and NIV+IPI treatment (3.1 weeks vs. 5.9 weeks, p=0.031).

CONCLUSION

This study revealed the general and specific occurrence pattern of ICI-induced irAEs in pan-cancers, which was deemed to aid the comprehensive understanding, timely detection, and effective management of ICI-induced irAEs.

Dual-Blockade Immune Checkpoint for Breast Cancer Treatment Based on a Tumor-Penetrating Peptide Assembling Nanoparticle

Cancer immunotherapy can enhance the antitumor effect of drugs through a combinatorial approach in a synergistic manner. However, the effective targeted delivery of various drugs remains a challenge. We generated a peptide assembling tumor-targeted nanodelivery system based on a breast cancer homing and penetrating peptide for the codelivery of a programmed cell death ligand 1 (PD-L1) small interfering RNA (siRNA) (siPD-L1) and an indoleamine 2,3-dioxygenase inhibitor as a dual blockade of an immune checkpoint. The vector is capable of specifically accumulating in the breast cancer tumor site in a way that allows the siRNA to escape from endosomal vesicles after being endocytosed by tumor cells. The drug within these cells then acts to block tryptophan metabolism. The results showed that locally released siPD-L1 and 1-methyl-dl-tryptophan favor the survival and activation of cytotoxic T lymphocytes, resulting in apoptosis of breast cancer cells. Therefore, this study provides a potential approach for treating breast cancer by blocking immunological checkpoints through the assembly of micelles with functional peptides.

Apatinib mesylate tablet in the treatment of advanced malignant melanoma

Background

Observing and studying clinical efficacy and safety of apatinib mesylate tablet in the treatment of advanced malignant melanoma (MM).

Methods

Retrospectively analyzing the clinical data of 22 patients with metastatic MM who had failed conventional chemotherapy from June 2016 to January 2018. All patients took 500 mg of apatinib mesylate tablets per day. The efficacy should be evaluated according to RECIST 1.1 criteria. Adverse events (AEs) should be graded according to NCI-CTCAE 4.0.

Results

There were two cases of partial remission (PR), 11 of stable disease (SD) and nine of progressive disease (PD) in the 22 patients with advanced MM, where the objective remission rate (ORR) was 9.1% and the disease control rate (DCR) was 59.1%. The median progression-free survival (PFS) was 7.5 months, and the 6-month progression-free survival rate (PFR) was 54.7%. Six patients died and the overall survival (OS) was not reached. AEs were controllable and all were in Grade 1–3.

Conclusion

Apatinib mesylate tablets have a certain curative effect on patients with malignant melanomas of Stage IV who failed conventional chemotherapy. Apatinib mesylate tablets at a daily dose of 500 mg are well tolerated by most patients.

Sequentially Responsive Therapeutic Peptide Assembling Nanoparticles for Dual-Targeted Cancer Immunotherapy

Combination therapeutic regimen is becoming a primary direction for current cancer immunotherapy to broad the antitumor response. Functional nanomaterials offer great potential for steady codelivery of various drugs, especially small molecules, therapeutic peptides, and nucleic acids, thereby realizing controllable drug release, increase of drug bioavailability, and reduction of adverse effects. Herein, a therapeutic peptide assembling nanoparticle that can sequentially respond to dual stimuli in the tumor extracellular matrix was designed for tumor-targeted delivery and on-demand release of a short d-peptide antagonist of programmed cell death-ligand 1 (^DPPA-1) and an inhibitor of idoleamine 2,3-dioxygenase (NLG919). By concurrent blockade of immune checkpoints and tryptophan metabolism, the nanoformulation increased the level of tumor-infiltrated cytotoxic T cells and in turn effectively inhibited melanoma growth. To achieve this, an amphiphilic peptide, consisting of a functional 3-diethylaminopropyl isothiocyanate (DEAP) molecule, a peptide substrate of matrix metalloproteinase-2 (MMP-2), and ^DPPA-1, was synthesized and coassembled with NLG919. The nanostructure swelled when it encountered the weakly acidic tumor niche where DEAP molecules were protonated, and further collapsed due to the cleavage of the peptide substrate by MMP-2 that is highly expressed in tumor stroma. The localized release of ^DPPA-1 and NLG919 created an environment which favored the survival and activation of cytotoxic T lymphocytes, leading to the slowdown of melanoma growth and increase of overall survival. Together, this study offers new opportunities for dual-targeted cancer immunotherapy through functional peptide assembling nanoparticles with design features that are sequentially responsive to the multiple hallmarks of the tumor microenvironment.

PD-1 and its ligands are important immune checkpoints in cancer

Checkpoint programmed death-1 (PD-1)/programmed cell death ligands (PD-Ls) have been identified as negative immunoregulatory molecules that promote immune evasion of tumor cells. The interaction of PD-1 and PD-Ls inhibits the function of T cells and tumor-infiltrating lymphocytes (TIL) while increasing the function of immunosuppressive regulatory T cells (Tregs). This condition causes the tumor cells to evade immune response. Thus, the blockade of PD-1/PD-L1 enhances anti-tumor immunity by reducing the number and/or the suppressive activity of Tregs and by restoring the activity of effector T cells. Furthermore, some monoclonal antibodies blockading PD-1/PD-Ls axis have achieved good effect and received Food and Drug Administration approval. The role of PD-1/PD-Ls in tumors has been well studied, but little is known on the mechanism by which PD-1 blocks T-cell activation. In this study, we provide a brief overview on the discovery and regulatory mechanism of PD-1 and PD-L1 dysregulation in tumors, as well as the function and signaling pathway of PD-1 and its ligands; their roles in tumor evasion and clinical treatment were also studied.

Epigallocatechin-3-gallate(EGCG) suppresses melanoma cell growth and metastasis by targeting TRAF6 activity

TRAF6 (TNF Receptor-Associated Factor 6) is an E3 ubiquitin ligase that contains a Ring domain, induces K63-linked polyubiquitination, and plays a critical role in signaling transduction. Our previous results demonstrated that TRAF6 is overexpressed in melanoma and that TRAF6 knockdown dramatically attenuates tumor cell growth and metastasis. In this study, we found that EGCG can directly bind to TRAF6, and a computational model of the interaction between EGCG and TRAF6 revealed that EGCG probably interacts with TRAF6 at the residues of Gln54, Gly55, Asp57 ILe72, Cys73 and Lys96. Among these amino acids, mutation of Gln54, Asp57, ILe72 in TRAF6 could destroy EGCG bound to TRAF6, furthermore, our results demonstrated that EGCG significantly attenuates interaction between TRAF6 and UBC13(E2) and suppresses TRAF6 E3 ubiquitin ligase activity in vivo and in vitro. Additionally, the phosphorylation of IκBα, p-TAK1 expression are decreased and the nuclear translocation of p65 and p50 is blocked by treatment with EGCG, leading to inactivation of the NF-κB pathway. Moreover, EGCG significantly inhibits cell growth as well as the migration and invasion of melanoma cells. Taken together, these findings show that EGCG is a novel E3 ubiquitin ligase inhibitor that could be used to target TRAF6 for chemotherapy or the prevention of melanoma.

The prevalence and clinicopathological features of programmed death-ligand 1 (PD-L1) expression: a pooled analysis of literatures

Background & Aims

Programmed death-ligand 1 (PD-L1) has been recognized as a critical and promising target in therapies that direct immune escape of cancers. However, its association with aggressive clinicopathological features in solid tumors remains unclear. We investigated this question by synthesizing published articles.

Methods

Electronic databases were searched for relevant studies. Outcomes of interest included age, gender, tumor size, tumor size, lymph node metastasis and tumor cell differentiation.

Results

A total of 61 studies involving 17 types of malignancies were included. The overall expression rate of PD-L1 was 44.5% (95% CI, 37.5% to 51.6 %). Patients with regional lymph node metastases (OR 1.38; P < 0.01), large size tumor (OR 1.89; P < 0.01) or poor differentiated tumors (OR 1.71; P < 0.01) were associated with higher PD-L1 expression rate. However, no significant association was observed between young and elder patients (OR 1.04; P = 0.58), or male and female patients (OR 1.13; P = 0.06). A numerically higher PD-L1 expression rate was detected in polyclonal antibodies (57.2%) than monoclonal antibodies (39.6%). In addition, the PD-L1 expression rate reported by studies from Asian areas (52.3%) was numerically higher than those from non-Asian areas, namely Caucasians (32.7%).

Conclusions

This meta-analysis indicated that patients with larger tumors, regional lymph node metastases, or poor-differentiated tumors were associated with a higher PD-L1 expression rate; in addition the expression rate of PD-L1 in Asians might be higher than that of Caucasians. This information might be useful in screening candidates for relevant tests and treatments.

Systematic Screening of Chemokines to Identify Candidates to Model and Create Ectopic Lymph Node Structures for Cancer Immunotherapy

The induction of ectopic lymph node structures (ELNs) holds great promise to augment immunotherapy against multiple cancers including metastatic melanoma, in which ELN formation has been associated with a unique immune-related gene expression signature composed of distinct chemokines. To investigate the therapeutic potential of ELNs induction, preclinical models of ELNs are needed for interrogation of these chemokines. Computational models provide a non-invasive, cost-effective method to investigate leukocyte trafficking in the tumor microenvironment, but parameterizing such models is difficult due to differing assay conditions and contexts among the literature. To better achieve this, we systematically performed microchemotaxis assays on purified immune subsets including human pan-T cells, CD4⁺ T cells, CD8⁺ T cells, B cells, and NK cells, with 49 recombinant chemokines using a singular technique, and standardized conditions resulting in a dataset representing 238 assays. We then outline a groundwork computational model that can simulate cellular migration in the tumor microenvironment in response to a chemoattractant gradient created from stromal, lymphoid, or antigen presenting cell interactions. The resulting model can then be parameterized with standardized data, such as the dataset presented here, and demonstrates how a computational approach can help elucidate developing ELNs and their impact on tumor progression.

MUC1 inhibition leads to decrease in PD-L1 levels via upregulation of miRNAs

The PD-L1/PD-1 pathway is a critical component of the immunosuppressive tumor microenvironment in acute myeloid leukemia (AML), but little is known about its regulation. We investigated the role of the MUC1 oncoprotein in modulating PD-L1 expression in AML. Silencing of MUC1 in AML cell lines suppressed PD-L1 expression without a decrease in PD-L1 mRNA levels, suggesting a post-transcriptional mechanism of regulation. We identified the microRNAs miR-200c and miR-34a as key regulators of PD-L1 expression in AML. Silencing of MUC1 in AML cells led to a marked increase in miR-200c and miR-34a levels, without changes in precursor microRNA, suggesting that MUC1 might regulate microRNA-processing. MUC1 signaling decreased the expression of the microRNA-processing protein DICER, via the suppression of c-Jun activity. NanoString (Seattle, WA, USA) array of MUC1-silenced AML cells demonstrated an increase in the majority of probed microRNAs. In an immunocompetent murine AML model, targeting of MUC1 led to a significant increase in leukemia-specific T cells. In concert, targeting MUC1 signaling in human AML cells resulted in enhanced sensitivity to T-cell-mediated lysis. These findings suggest MUC1 is a critical regulator of PD-L1 expression via its effects on microRNA levels and represents a potential therapeutic target to enhance anti-tumor immunity.

Regulatory T cells as suppressors of anti-tumor immunity: Role of metabolism

Novel concepts in immunometabolism support the hypothesis that glucose consumption is also used to modulate anti-tumor immune responses, favoring growth and expansion of specific cellular subsets defined in the past as suppressor T cells and currently reborn as regulatory T (Treg) cells. During the 1920s, Otto Warburg and colleagues observed that tumors consumed high amounts of glucose compared to normal tissues, even in the presence of oxygen and completely functioning mitochondria. However, the role of the Warburg Effect is still not completely understood, particularly in the context of an ongoing anti-tumor immune response. Current experimental evidence suggests that tumor-derived metabolic restrictions can drive T cell hyporesponsiveness and immune tolerance. For example, several glycolytic enzymes, deregulated in cancer, contribute to tumor progression independently from their canonical metabolic activity. Indeed, they can control apoptosis, gene expression and activation of specific intracellular pathways, thus suggesting a direct link between metabolic switches and pro-tumorigenic transcriptional programs. Focus of this review is to define the specific metabolic pathways controlling Treg cell immunobiology in the context of anti-tumor immunity and tumor progression.

PD-1 expression by canine T cells and functional effects of PD-1 blockade

The co-inhibitory checkpoint molecule programmed death receptor 1 (PD-1) can trigger T cell functional exhaustion upon binding to its ligand PD-L1 expressed on tumour cells or macrophages. PD-1 blocking antibodies have generated remarkable results in human cancer patients, including inducing durable responses in a number of advanced cancers. Therefore, monoclonal antibodies specific for canine PD-1 were assessed for T cell binding and induction of functional activation. A total of 5-10% of CD4 T cells and 20-25% of CD8 T cells from healthy dogs expressed PD-1, and PD-1 expression was upregulated on T cells from dogs with cancer. Functionally, PD-1 antibodies significantly enhanced T-cell activation, as assessed by proliferation and interferon-gamma (IFN-γ) production. PD-1 antibodies also reversed T-cell suppression induced by canine soluble PD-L1 and by tumour cells and tumour explant fragments. These findings indicate that PD-1 antibodies have potential for use in cancer immunotherapy in dogs.

PD-1 Suppresses Development of Humoral Responses That Protect against Tn-Bearing Tumors

Tn is a carbohydrate antigen uniquely exposed on tumor mucins and, thus, an ideal target for immunotherapy. However, it has been difficult to elicit protective antibody responses against Tn antigen and other tumor-associated carbohydrate antigens. Our study demonstrates this can be attributed to PD-1 immuno-inhibition. Our data show a major role for PD-1 in suppressing mucin- and Tn-specific B-cell activation, expansion, and antibody production important for protection against Tn-bearing tumor cells. These Tn/mucin-specific B cells belong to the innate-like B-1b cell subset typically responsible for T cell-independent antibody responses. Interestingly, PD-1-mediated regulation is B cell-intrinsic and CD4⁺ cells play a key role in supporting Tn/mucin-specific B-cell antibody production in the context of PD-1 deficiency. Mucin-reactive antibodies produced in the absence of PD-1 inhibition largely belong to the IgM subclass and elicit potent antitumor effects via a complement-dependent mechanism. The identification of this role for PD-1 in regulating B cell-dependent antitumor immunity to Tn antigen highlights an opportunity to develop new therapeutic strategies targeting tumor-associated carbohydrate antigens. Cancer Immunol Res; 4(12); 1027-37. ©2016 AACR.

Inactivated Tianjin strain, a novel genotype of Sendai virus, induces apoptosis in HeLa, NCI-H446 and Hep3B cells

The Sendai virus strain Tianjin is a novel genotype of the Sendai virus. In previous studies, ultraviolet-inactivated Sendai virus strain Tianjin (UV-Tianjin) demonstrated antitumor effects on human breast cancer cells. The aim of the present study was to investigate the in vitro antitumor effects of UV-Tianjin on the human cervical carcinoma HeLa, human small cell lung cancer NCI-H446 and human hepatocellular carcinoma Hep 3B cell lines, and the possible underlying mechanisms of these antitumor effects. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay revealed that UV-Tianjin treatment inhibited the proliferation of HeLa, NCI-H446 and Hep 3B cells in a dose- and time-dependent manner. Hoechst and Annexin V-fluorescein isothiocyanate/propidium iodide double staining indicated that UV-Tianjin induced dose-dependent apoptosis in all three cell lines with the most significant effect observed in the HeLa cell line. In the HeLa cell line, UV-Tianjin-induced apoptosis was further confirmed by the disruption of the mitochondria membrane potential and the activation of caspases, as demonstrated by fluorescent cationic dye and colorimetric assays, respectively. In addition, western blot analysis revealed that UV-Tianjin treatment resulted in significant upregulation of cytochrome c, apoptosis protease activating factor-1, Fas, Fas ligand and Fas-associated protein with death domain, and activated caspase-9, −8 and −3 in HeLa cells. Based on these results, it is hypothesized that UV-Tianjin exhibits anticancer activity in HeLa, NCI-H446 and Hep 3B cell lines via the induction of apoptosis. In conclusion, the results of the present study indicate that in the HeLa cell line, intrinsic and extrinsic apoptotic pathways may be involved in UV-Tianjin-induced apoptosis.

Antibiotic drug tigecycline inhibits melanoma progression and metastasis in a p21CIP1/Waf1-dependent manner

Antibiotics are common drugs with low toxicity but high effectiveness. They have been suggested to be drug candidates for cancer therapy in recent years. Here, we tried to investigate the antitumour effect of tigecycline on malignant melanoma. We showed that tigecycline dramatically inhibited cell proliferation and induced cell cycle arrest at G0/G1 phase. At the same time, tigecycline suppressed cell invasion and migration through preventing epithelial-mesenchymal transition (EMT) process. In addition, tigecycline also significantly blocked tumor growth in vivo. Expression of cell cycle-related proteins were investigated and resulted in downregulation of G1/S checkpoint proteins, such as CDK2 and Cyclin E. However, cyclin-dependent kinase inhibitor 1 (CDKN1A, p21(CIP1/Waf1)) was downregulated after tigecycline treatment, which was not conformed to its conventional function. To explain this, we overexpressed p21 in melanoma cells. We found that p21 overexpression significantly rescued tigecycline-induced cell proliferation inhibition as well as migration and invasion suppression. Taken together, our results revealed that the essential role of p21 in the inhibitory effect of tigecycline on proliferation, migration and invasion of melanoma. Tigecycline might act as a candidate therapeutic drug for treatment of patients suffering from malignant melanoma.

Pembrolizumab for the treatment of thoracic malignancies: current landscape and future directions

New insights into the interaction between the immune system and the tumor microenvironment have led to the development of checkpoint inhibitors that target the PD-1/PD-L1 pathway. Pembrolizumab (MK-3475, lambrolizumab, Keytruda®) is a PD-1 inhibitor that has shown clinical activity in a variety of solid tumors and is currently approved for the second-line treatment of PD-L1-positive non-small-cell lung cancer and for unresectable/metastatic melanoma. This article will discuss the results of early-phase trials of pembrolizumab in thoracic malignancies as well as ongoing studies aimed to confirm clinical benefit.

Nivolumab and pembrolizumab as immune-modulating monoclonal antibodies targeting the PD-1 receptor to treat melanoma

Malignant melanoma is an important issue in oncology due to its high incidence, high mortality, and resistance to systemic therapy; however, targeted immunotherapy has noticeably improved the survival rates of melanoma patients. Promising targeted immunotherapies for malignant melanoma include the blockade of immune checkpoints with antibodies targeting cytotoxic T lymphocyte-associated antigen 4 and the programmed cell death protein 1 pathway. The US FDA-approved antibody ipilimumab targets cytotoxic T lymphocyte-associated antigen 4; however, it was limited by toxicity and a low response. Nivolumab and pembrolizumab (formerly lambrolizumab), the two FDA-approved anti-programmed death-1 monoclonal antibodies, show highly durable response rates and long-term safety, validating the importance of the programmed cell death protein 1 pathway blockade for treatment of malignant melanoma.

Immunotherapy in Melanoma, Gastrointestinal (GI), and Pulmonary Malignancies

Oncologic immunotherapy involves stimulating the immune system to more effectively identify and eradicate tumor cells that have successfully adapted to survive the body's natural immune defenses. Immunotherapy has shown great promise thus far by prolonging the lives of patients with a variety of malignancies, and has added a crucial new set of tools to the oncologists' armamentarium. The aim of this paper is to provide an overview of immunotherapy treatment options that are currently available and under active research for melanoma, gastrointestinal (esophageal, gastric, pancreatic, and colorectal), and pulmonary malignancies. Potential biomarkers that may predict favorable responses to immunotherapies are discussed where applicable, as are future avenues of research in this rapidly evolving field.