Mechanistic and pharmacologic insights on immune checkpoint inhibitors

Germline modifiers of the tumor immune microenvironment implicate drivers of cancer risk and immunotherapy response

With the continued promise of immunotherapy for treating cancer, understanding how host genetics contributes to the tumor immune microenvironment (TIME) is essential to tailoring cancer screening and treatment strategies. Here, we study 1084 eQTLs affecting the TIME found through analysis of The Cancer Genome Atlas and literature curation. These TIME eQTLs are enriched in areas of active transcription, and associate with gene expression in specific immune cell subsets, such as macrophages and dendritic cells. Polygenic score models built with TIME eQTLs reproducibly stratify cancer risk, survival and immune checkpoint blockade (ICB) response across independent cohorts. To assess whether an eQTL-informed approach could reveal potential cancer immunotherapy targets, we inhibit CTSS, a gene implicated by cancer risk and ICB response-associated polygenic models; CTSS inhibition results in slowed tumor growth and extended survival in vivo. These results validate the potential of integrating germline variation and TIME characteristics for uncovering potential targets for immunotherapy.

Blood cell counts can predict adverse events of immune checkpoint inhibitors: A systematic review and meta-analysis

Background

Cancer is concerning owing to its high mortality rate. Consequently, methods of prolonging the life of patients with cancer have become the primary focus of attention research. In recent years, immune checkpoint inhibitors (ICIs) have achieved good clinical efficacy as antitumor drugs; however, their severe adverse effects have made their use challenging. In order to clarify the predictors of adverse effects, scientists have conducted a series of studies. Blood counts can potentially monitor risk factors associated with the occurrence of immune-related adverse events (irAEs). Herein, a meta-analysis was performed to clarify further the guiding significance of blood counts in the clinical setting.

Methods

Studies that satisfied the inclusion criteria were obtained by searching the database. Included studies were those in which irAEs had been observed, and evidence of an association between blood counts and irAEs was reported. The included ones were evaluated for quality. In addition to sensitivity analysis and subgroup analysis, a meta-analysis was performed using the odds ratio (OR) and 95% confidence interval (CI) for each study.

Results

A total of 18 articles were included in our study. The analyses were performed separately according to different blood cell count indicators. The blood cell count metrics associated with irAEs were: absolute eosinophil count, neutrophil: lymphocyte ratio, and platelet: lymphocyte ratio.

Conclusion

Our review and meta-analysis of studies suggest that absolute eosinophil count, neutrophil: lymphocyte ratio, and platelet: lymphocyte ratio may serve as predictors of the emergence of irAEs. Given the small number of studies focusing on the relationship between patient blood cell counts and the risk of irAEs, future studies need to further explore the mechanisms of occurrence and potential associations.

Molecular Taxonomy and Immune Checkpoint Therapy in Bladder Cancer

Bladder cancer is a heterogeneous disease, which exhibits a wide spectrum of clinical and pathologic features. Recent genomic studies have revealed that distinct molecular alterations may underlie the diverse clinical behaviors of bladder cancer, leading to a novel molecular classification. The intrinsic molecular subtypes exhibit distinct gene expression signatures and different clinicopathologic features. Genomic alterations also underlie the development of bladder cancer histologic subtypes. Genomic characterization provides new insights to understanding the biology of bladder cancer and improves the diagnosis and treatment of this complex disease. Biomarkers can aid the selection of patients for immune checkpoint therapy.

Orchestrated Action of AMPK Activation and Combined VEGF/PD-1 Blockade with Lipid Metabolic Tunning as Multi-Target Therapeutics against Ovarian Cancers

Ovarian cancer is one of the most lethal gynecological malignancies worldwide, and chemoresistance is a critical obstacle in the clinical management of the disease. Recent studies have suggested that exploiting cancer cell metabolism by applying AMP-activated protein kinase (AMPK)-activating agents and distinctive adjuvant targeted therapies can be a plausible alternative approach in cancer treatment. Therefore, the perspectives about the combination of AMPK activators together with VEGF/PD-1 blockade as a dual-targeted therapy against ovarian cancer were discussed herein. Additionally, ferroptosis, a non-apoptotic regulated cell death triggered by the availability of redox-active iron, have been proposed to be governed by multiple layers of metabolic signalings and can be synergized with immunotherapies. To this end, ferroptosis initiating therapies (FITs) and metabolic rewiring and immunotherapeutic approaches may have substantial clinical potential in combating ovarian cancer development and progression. It is hoped that the viewpoints deliberated in this review would accelerate the translation of remedial concepts into clinical trials and improve the effectiveness of ovarian cancer treatment.

Distinct Immune Signatures Indicative of Treatment Response and Immune-Related Adverse Events in Melanoma Patients under Immune Checkpoint Inhibitor Therapy

To identify potential early biomarkers of treatment response and immune-related adverse events (irAE), a pilot immune monitoring study was performed in stage IV melanoma patients by flow cytometric analysis of peripheral blood mononuclear cells (PBMC). Overall, 17 patients were treated with either nivolumab or pembrolizumab alone, or with a combination of nivolumab and ipilimumab every three weeks. Of 15 patients for which complete response assessment was available, treatment responders (n = 10) as compared to non-responders (n = 5) were characterized by enhanced PD-1 expression on CD8+ T cells immediately before treatment (median ± median absolute deviation/MAD 26.7 ± 10.4% vs. 17.2 ± 5.3%). Responders showed a higher T cell responsiveness after T cell receptor ex vivo stimulation as determined by measurement of programmed cell death 1 (PD-1) expression on CD3+ T cells before the second cycle of treatment. The percentage of CD8+ effector memory (CD8+CD45RA-CD45RO+CCR7-) T cells was higher in responders compared to non-responders before and immediately after the first cycle of treatment (median ± MAD 39.2 ± 7.3% vs. 30.5 ± 4.1% and 37.7 ± 4.6 vs. 24.0 ± 6.4). Immune-related adverse events (irAE) were accompanied by a higher percentage of activated CD4+ (CD4+CD38+HLADR+) T cells before the second treatment cycle (median ± MAD 14.9 ± 3.9% vs. 5.3 ± 0.4%). In summary, PBMC immune monitoring of immune-checkpoint inhibition (ICI) treatment in melanoma appears to be a promising approach to identify early markers of treatment response and irAEs.

Severe Acute Kidney Injury Due to Nivolumab/Ipilimumab-induced Granulomatosis and Fibrinoid Vascular Necrosis

Immune-checkpoint inhibitors have revolutionized the treatment of cancers in recent years. Four drugs have obtained FDA approval in a variety of cancer types. Immune-related adverse events are common and occur in up to 60% of treated patients. Common manifestations of immune-related adverse events include rash, colitis, hepatitis, and hypophysitis. Most cases are mild to moderate in grade; however, severe manifestations with lethal outcomes have been described. Acute kidney injury is reported as a rare complication. In this case report, we present a patient with metastatic melanoma undergoing combined immune-checkpoint inhibitor therapy and displaying multiple immune-related adverse events. Despite receiving systemic steroid therapy for extrarenal immune-related adverse events, the patient developed acute progressive kidney injury requiring renal replacement therapy. Findings on renal biopsy included granulomatous interstitial nephritis, vasculitis, and thrombotic microangiopathy-like lesions. This case indicates that, although severe acute kidney injury is a rare complication of immune-checkpoint inhibitors, fulminant cases do occur and can be resistant to therapeutic intervention.

Benefit and danger from immunotherapy in myasthenia gravis

In the last years, significant advances have improved the knowledge of myasthenia gravis (MG) immunopathogenesis and have enabled to realize new molecules with a selective action targeting compounds of the immunological system. This review discusses emerging treatments for MG, including complement inhibitors, neonatal Fc receptor targeting agents, and B cell interfering drugs, focusing on benefit and danger. In the second section of the review, several related adverse events of immunotherapy, including MGonset, are debated.

Germline genetic contribution to the immune landscape of cancer

Understanding the contribution of the host's genetic background to cancer immunity may lead to improved stratification for immunotherapy and to the identification of novel therapeutic targets. We investigated the effect of common and rare germline variants on 139 well-defined immune traits in ∼9000 cancer patients enrolled in TCGA. High heritability was observed for estimates of NK cell and T cell subset infiltration and for interferon signaling. Common variants of IFIH1, TMEM173 (STING1), and TMEM108 were associated with differential interferon signaling and variants mapping to RBL1 correlated with T cell subset abundance. Pathogenic or likely pathogenic variants in BRCA1 and in genes involved in telomere stabilization and Wnt-β-catenin also acted as immune modulators. Our findings provide evidence for the impact of germline genetics on the composition and functional orientation of the tumor immune microenvironment. The curated datasets, variants, and genes identified provide a resource toward further understanding of tumor-immune interactions.

Anticancer nanocage platforms for combined immunotherapy designed to harness immune checkpoints and deliver anticancer drugs

The interaction of programmed cell death 1 ligand 1 (PD-L1) with its receptor, programmed cell death 1 (PD-1), inhibits T cell responses. Monoclonal antibodies that block this interaction have been shown effective as immunotherapy. However, only a subset of cancers exhibits a durable response to PD-1/PD-L1 blockade. Moreover, antibody-based immune checkpoint blockade is costly and is occasionally accompanied by systemic side effects. To overcome these limitations of antibody-based immune checkpoint blockade, an immune checkpoint-blocking ferritin nanocage displaying 24 PD-L1 binding peptides (PD-L1pep1) on its surface was designed and constructed. These ferritin nanocages displaying PD-L1pep1 (PpNF) specifically bind to PD-L1 expressed on cancer cells or to purified PD-L1 with a ~30 nM binding affinity. The addition of PpNF to co-cultures of T cells and cancer cells inhibited PD-1/PD-L1 interactions and restored T cell activities. In a mouse model of syngeneic colon cancer, PpNF specifically targeted tumors and showed antitumor activity. Moreover, PpNF nanocages encapsulating the chemotherapeutic drug doxorubicin had more potent antitumor activity than a monoclonal antibody against PD-L1. These results demonstrate that ferritin nanocages displaying surface PD-L1pep1 can be efficiently applied for immunotherapy, especially when encapsulating small chemotherapeutic drugs. These nanocages may have promise as an immunotherapeutic nanomedicine against various solid tumors.

Nivolumab and ipilimumab immunotherapy for hemodialysis patients with advanced renal cell carcinoma

Combined immune checkpoint blockade with nivolumab and ipilimumab is standard therapy for the treatment of patients with previously untreated advanced renal cell carcinoma who are at intermediate or poor risk. However, data about the safety and efficacy of combined immune checkpoint blockade with nivolumab and ipilimumab in patients on hemodialysis are limited. Renal function has no known clinically important effects on the pharmacokinetics and clearance of nivolumab and ipilimumab. Further, most immune-related adverse events in patients on hemodialysis are thought to be manageable with the same treatments applied in patients with normal renal function. We present a case of advanced clear-cell renal cell carcinoma in a patient on hemodialysis who received combined immune checkpoint blockade with nivolumab and ipilimumab and who showed no evident signs of immune-related adverse events. Here, we confirm the safety and efficacy of combined immune checkpoint blockade with nivolumab and ipilimumab in a patient on hemodialysis.

Role of tumor microenvironment in the regulation of PD-L1: A novel role in resistance to cancer immunotherapy

Tumor evasion from the host immune system is a substantial strategy for tumor development and survival. The expression of many immune checkpoint proteins in cancer cells is a mechanism by which tumor cells escape from the immune system. Among the well-known immune checkpoints that can tremendously affect tumor development and cancer therapy are the programmed death-ligand-1/programmed death-1 (PD-L1/PD-1). To tackle this phenomenon and improve the therapeutic strategies in cancer treatment, the blockade of the PD-L1/PD-1 pathway is introduced as a target, but the therapeutic advantage of PD L1/PD-1 blockade has not fulfilled the expectations. This condition may be associated with a different type of resistance in a considerable number of patients. A crucial issue to conquer resistance against immune checkpoint blockade therapy is to understand how PD-L1 level is regulated. However, the mechanisms by which the PD-L1 expression is regulated are complicated, and they can occur at different levels from signaling pathways to posttranscriptional levels. For example, various transcriptional factors, such as hypoxia-inducible factor-1, nuclear factor-κΒ, interferon-γ, STAT3, MYC, and AP-1 can regulate the PD-L1 distribution at the transcriptional level. Herein, we tried to focus on the most important regulatory mechanisms of PD-L1 by inducible agents in the tumor cells, such as signaling pathways, transcriptional factors, and posttranscriptional factors. Finally, these approaches may open up new windows for targeting tumor immune evasion and suggest the novel suppressors of PD-L1 for efficient therapeutics.

Cytokines as potential combination agents with PD-1/PD-L1 blockade for cancer treatment

Immunotherapy has caused a paradigm shift in the treatment of several malignancies, particularly the blockade of programmed death-1 (PD-1) and its specific receptor/ligand PD-L1 that have revolutionized the treatment of a variety of malignancies, but significant durable responses only occur in a small percentage of patients, and other patients failed to respond to the treatment. Even those who initially respond can ultimately relapse despite maintenance treatment, there is considerable potential for synergistic combinations of immunotherapy and chemotherapy agents with immune checkpoint inhibitors into conventional cancer treatments. The clinical experience in the use of cytokines in the clinical setting indicated the efficiency of cytokine therapy in cancer immunotherapy. Combinational approaches to enhancing PD-L1/PD-1 pathways blockade efficacy with several cytokines such as interleukin (IL)-2, IL-15, IL-21, IL-12, IL-10, and interferon-α (IFN-α) may result in additional benefits. In this review, the current state of knowledge about PD-1/PD-L1 inhibitors, the date in the literature to ascertain the combination of anti-PD-1/PD-L1 antibodies with cytokines is discussed. Finally, it is noteworthy that novel therapeutic approaches based on the efficient combination of recombinant cytokines with the PD-L1/PD-1 blockade therapy can enhance antitumor immune responses against various malignancies.

Nivolumab for the treatment of unresectable pleural mesothelioma

Introduction: Platinum-based chemotherapy is the current first-line standard therapy for unresectable malignant pleural mesothelioma (MPM). Recently, immune-checkpoint inhibitors (ICI) have been intensively investigated as treatment options for this disease. Nivolumab, an anti-programmed cell death (PD)-1 agent, was one of the first drugs used and is representative of available ICIs.Areas covered: This review discusses previous relevant reports and current ongoing trials of nivolumab. The efficacy and safety of nivolumab have been investigated mostly in second-line or later treatment settings as both monotherapy and in combination with other ICIs. Particularly, nivolumab monotherapy yielded promising efficacy with an objective response rate of 29% and median overall survival of 17.3 months in salvage settings in the single-arm, Japanese phase 2 trial (MERIT). Notably, the study led to Japanese approval of nivolumab for unresectable recurrent MPM. Several trials with monotherapy or cotherapy with nivolumab have commenced, including randomized trials of nivolumab monotherapy vs. placebo in the salvage setting, and cotherapy with nivolumab and ipilimumab vs. the platinum doublet in the frontline setting.Expert opinion: Nivolumab seems like a reasonable option for unresectable, relapsed MPM despite the lack of randomized trial data. Ongoing pivotal trials will confirm its efficacy.

PD-1 Inhibitor-associated Myopathies: Emerging Immune-mediated Myopathies

Programmed death-1 (PD-1) inhibitors are increasingly used in cancer immunotherapy. Various immune-related adverse events are reported, including infrequent individual case reports of myositis or rhabdomyolysis. The frequency and diagnostic spectrum of immune-related adverse events affecting skeletal muscle in PD-1 inhibitor-treated patients are unknown. We searched the Mayo Clinic Pharmacy database (2014-2016) to identify patients who developed myopathies during or after PD-1 inhibitor therapy. Among 654 cancer patients received PD-1 inhibitors (pembrolizumab=389; nivolumab=264; both=1), we identified 5 patients (pembrolizumab=5) with biopsy-proven myopathies (2 necrotizing myopathy, 1 early dermatomyositis, and 2 nonspecific myopathy). Four patients developed concomitant autoimmune disorders. Weakness occurred after a median of 2 treatments (range, 1-4). All patients had proximal or axial weakness. Four patients had either bulbar or extraocular weakness, but only 1 patient had acetylcholine receptor antibodies. Creatine kinase levels were elevated in 3 patients (necrotizing myopathy=2; nonspecific myopathy=1). Brain magnetic resonance imaging revealed abnormal T2 signal and enhancement of extraocular muscles in 1 patient with ophthalmoparesis. Pembrolizumab was discontinued in all patients. All patients received immunosuppressive therapy, with fatal outcome in 2 necrotizing myopathy patients and favorable outcome in others. We conclude that myopathy is a rare, but unique complication of PD-1 inhibitors with frequent involvement of extraocular or bulbar muscles, mimicking myasthenia gravis. Muscle biopsy is an important test for PD-1 inhibitor-treated patients who develop oculobulbar weakness and hyperCKemia, to distinguish patients with necrotizing myopathy from myasthenia gravis. Necrotizing myopathy patients may require more aggressive immunotherapy due to their grave prognosis.

Can CpG methylation serve as surrogate markers for immune infiltration in cancer?

Recent reports describe how genome-wide transcriptional analysis of cancer tissues can be exploited to identify molecular signatures of immune infiltration in cancer. We hypothesize that immune infiltration in cancer may also be defined by changes in certain epigenetic signatures. In this context, a primary objective is to identify site-specific CpG markers whose levels of methylation may be highly indicative of known transcriptional markers of immune infiltration such as GZMA, PRF1, T cell receptor genes, PDCD1, and CTLA4. This has been accomplished by integrating genome-wide transcriptional expression and methylation data for different types of cancer (melanoma, kidney cancers, lung cancers, gliomas, head and neck cancer). Our findings establish that cancers of related histology also have a high degree of similarity in immune-infiltration CpG markers. For example, the epigenetic immune infiltration signatures in lung adenocarcinoma (LUAD), mesothelioma (MESO), lung squamous cell carcinoma (LUSC), and head and neck squamous cell carcinoma (HNSC) are distinctly similar. So are glioblastoma multiforme (GBM) and brain lower grade glioma (LGG); and kidney renal papillary cell carcinoma (KIRP) and kidney renal clear cell carcinoma (KIRC). Kidney chromophobe (KICH), on the other hand has markers that are unique to this cohort. The strong relationships between immune infiltration and CpG methylation (for certain sites) in cancer tissues were not observed upon integrated analysis of publicly available cancer cell line datasets. Results from comparative pathways analyses offer further justification to methylation at certain CpG sites as being indicators of cancer immune infiltration, and possibly of predicting patient response to immunotherapeutic drugs. Achieving this target objective would significantly enhance therapeutic outcomes employing immunotherapy through focused patient-centric personalized medicine.

Phenotypic and genotypic heterogeneity of Lynch syndrome: a complex diagnostic challenge

Lynch syndrome is the hereditary disorder that most frequently predisposes to colorectal cancer as well as predisposing to a number of extracolonic cancers, most prominently endometrial cancer. It is caused by germline mutations in the mismatch repair genes. Both its phenotype and genotype show marked heterogeneity. This review gives a historical overview of the syndrome, its heterogeneity, its genomic landscape, and its implications for complex diagnosis, genetic counseling and putative implications for immunotherapy.

Pathways- and epigenetic-based assessment of relative immune infiltration in various types of solid tumors

Recent clinical studies document the power of immunotherapy in treating subsets of patients with advanced cancers. In this context and with multiple cancer immunotherapeutics already evaluated in the clinic and a large number in various stages of clinical trials, it is imperative to comprehensively examine genomics data to better comprehend the role of immunity in different cancers in predicting response to therapy and in directing appropriate therapies. The approach we chose is to scrutinize the pathways and epigenetic factors predicted to drive immune infiltration in different cancer types using publicly available TCGA transcriptional and methylation datasets, along with accompanying clinico-pathological data. We observed that the relative activation of T cells and other immune signaling pathways differs across cancer types. For example, pathways related to activation and proliferation of helper and cytotoxic T cells appear to be more highly enriched in kidney, skin, head and neck, and esophageal cancers compared to those of lung, colorectal, and liver or bile duct cancers. The activation of these immune-related pathways positively associated with prognosis in certain cancer types, most notably melanoma, head and neck, and cervical cancers. Integrated methylation and expression data (along with publicly available, ENCODE-generated histone ChIP Seq and DNAse hypersensitivity data) predict that epigenetic regulation is a primary factor driving transcriptional activation of a number of genes crucial to immunity in cancer, including T cell receptor genes (e.g., CD3D, CD3E), CTLA4, and GZMA. However, the extent to which epigenetic factors (primarily methylation at promoter regions) affect transcription of immune-related genes may vary across cancer types. For example, there is a high negative correlation between promoter CpG methylation and CD3D expression in renal and thyroid cancers, but not in brain tumors. The types of analyses we have undertaken provide insights into the relationships between immune modulation and cancer etiology and progression, offering clues into ways of therapeutically manipulating the immune system to promote immune recognition and immunotherapy.

Immune-related adverse events of immune checkpoint inhibitors: a brief review

Immune checkpoint inhibitors (icis) such as inhibitors of ctla-4, PD-1, and PD-L1, given as monotherapy or combination therapy have emerged as effective treatment options for immune-sensitive solid tumours and hematologic malignancies. The benefits of icis can be offset by immune-related adverse events (iraes) that leave all organ systems vulnerable and subsequently increase the risk for morbidity and mortality. Because of fluctuating onset and prolonged duration, the toxicities associated with iraes represent a shift from the understanding of conventional anticancer toxicities. The ctla-4 and PD-1/PD-L1 inhibitors modulate T-cell response differently, resulting in distinct toxicity patterns, toxicity kinetics, and dose-toxicity relationships. Using individualized patient education, screening, and assessment for the early identification of iraes is key to proactive management and is therefore key to improving outcomes and prolonging therapy. Management of iraes is guided by appropriate grading, which sets the stage for the treatment setting (outpatient vs. inpatient), ici treatment course (delay vs. discontinuation), supportive care, corticosteroid use, organ specialist consultation, and additional immunosuppression. Health care professionals in oncology must work collaboratively with emergency and community colleagues to facilitate an understanding of iraes in an effort to optimize seamless care.

Pembrolizumab for the first-line treatment of non-small cell lung cancer

INTRODUCTION

Platinum-based chemotherapy had long played a role as standard therapy for the first-line treatment of advanced or recurrent non-small cell lung cancer (NSCLC). However, immune checkpoint inhibitors such as pembrolizumab, a monoclonal antibody that prevents programmed death protein 1 (PD-1) receptor, have brought a paradigm shift in this field. Areas covered: In this article, we review the relevant literatures and ongoing trials on the first-line treatment of pembrolizumab. Especially, in two pivotal phase III trials, KEYNOTE-024 and -189, both pembrolizumab monotherapy and combined pembrolizumab plus chemotherapy significantly prolonged overall survival (OS) compared to the existing platinum-based chemotherapy. Currently, multiple trials with combination therapy of pembrolizumab and other agents have been conducted, and further evidences are expected to be created. Expert opinion: Immune checkpoint inhibitors that block the PD-1/PD-L1 pathway are essential drugs for advanced or recurrent NSCLC, among which pembrolizumab becomes one of the standards of care in the first-line of NSCLC. For further improvement in efficacy of pembrolizumab, it is necessary to clarify the identification of biomarkers exclusive to PD-L1 expression, predictive factors for patients who benefit most from the agent.

Duokines: a novel class of dual-acting co-stimulatory molecules acting in cis or trans

Co-stimulatory signals induced by ligands of the tumor necrosis factor superfamily (TNFSF) play a central role in T cell activation and have emerged as a promising strategy in cancer immunotherapy. Here, we established a novel class of bifunctional co-stimulatory fusion proteins with the aim to boost T cell activation at the level of T cell – antigen-presenting cell (APC) interaction. These novel dual-acting cytokine fusion proteins were created by connecting two different homotrimeric TNFSF ligands to form homotrimeric bifunctional molecules (Duokines) or by connecting single-chain derivatives of two different homotrimeric TNFSF with a single, flexible linker (single-chain Duokines, scDuokines). By linking the TNFSF ligands 4-1BBL, OX40L and CD27L in all possible combinations, cis-acting Duokines were generated that act on the same or adjacent T cells, while combining CD40L with 4-1BBL, OX40L and CD27L resulted in trans-acting Duokines acting simultaneously on APCs and T cells. In vitro, co-stimulation of T cells was seen for cis- and trans-acting Duokines and scDuokines in an antigen-independent as well as antigen-specific setting. Trans-acting molecules furthermore activated B cells, which represent a subclass of APCs. In a pilot experiment using the syngeneic B16-FAP mouse tumor model scDuokines displayed antitumoral activity in vivo in combination with a primary T cell-activating bispecific antibody, evident from reduced number of lung metastasis compared to the antibody-only treated group. Our data show that the bifunctional, co-stimulatory duokines are capable to enhance T cell-mediated anti-tumor immune responses, suggesting that they can serve as a new class of immuno-stimulatory molecules for use in cancer immunotherapy strategies.

A Mechanistic Model for Predicting Cell Surface Presentation of Competing Peptides by MHC Class I Molecules

Major histocompatibility complex-I (MHC-I) molecules play a central role in the immune response to viruses and cancers. They present peptides on the surface of affected cells, for recognition by cytotoxic T cells. Determining which peptides are presented, and in what proportion, has profound implications for developing effective, medical treatments. However, our ability to predict peptide presentation levels is currently limited. Existing prediction algorithms focus primarily on the binding affinity of peptides to MHC-I, and do not predict the relative abundance of individual peptides on the surface of antigen-presenting cells in situ which is a critical parameter for determining the strength and specificity of the ensuing immune response. Here, we develop and experimentally verify a mechanistic model for predicting cell-surface presentation of competing peptides. Our approach explicitly models key steps in the processing of intracellular peptides, incorporating both peptide binding affinity and intracellular peptide abundance. We use the resulting model to predict how the peptide repertoire is modified by interferon-γ, an immune modulator well known to enhance expression of antigen processing and presentation proteins.

Anti-PD-1 Therapy-Associated Perforating Colitis

Inhibition of immune checkpoint T cell regulatory molecules by using programmed cell death protein 1 (PD-1), or its ligand (PDL-1), and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) has been increasingly used to treat advanced malignancies. The immune-related adverse effects associated with these treatments such as diarrhea, colitis, and CTLA-4 treatment-associated perforating colitis have been reported. However, anti-PD-1/PD-L1-associated perforating colitis has rarely been reported. We report a case of colonic perforation in a patient recently treated with pembrolizumab, a PD-1 inhibitor for metastatic melanoma. Awareness of anti-PD-1/PD-L1-associated colitis and perforation will facilitate a timely diagnosis and management as they are increasingly used in oncology.

Pseudoprogression manifesting as recurrent ascites with anti-PD-1 immunotherapy in urothelial bladder cancer

BACKGROUND

Immunotherapies targeting the PD-1 checkpoint pathway have recently gained regulatory approval in numerous cancer types. With the widespread use of immune checkpoint therapies, varying patterns of responses and immune-related adverse events are being observed.

CASE PRESENTATION

In this case, we highlight a patient who developed recurrent, large-volume ascites, while simultaneously having a 49% reduction in peritoneal tumor lesion size by RECIST criteria. Sampling of the fluid revealed high levels of IL-6 and IL-15. Cytology revealed no malignant cells on 4 separate paracenteses over a period of 6 weeks. Cell counts revealed that 45% of cells were lymphocytes, and further analysis was performed by fluorescence-activated cell sorting (FACS). The majority of lymphocytes were CD8⁺, of which 78% were PD-1⁺ and 43% were HLA-DR⁺ indicating an activated phenotype.

CONCLUSIONS

In summary, treatment with anti-PD-1 therapy may result in pseudoprogression manifested by ascitic fluid accumulation due to the influx of activated T cells. Since worsening of ascites is typically associated with disease progression, it is important to consider the possibility of pesudoprogression in such patients undergoing therapy with immune checkpoint inhibitors.

Overexpression of adhesion molecules and barrier molecules is associated with differential infiltration of immune cells in non-small cell lung cancer

Immunotherapy is emerging as a promising option for lung cancer treatment. Various endothelial adhesion molecules, such as integrin and selectin, as well as various cellular barrier molecules such as desmosome and tight junctions, regulate T-cell infiltration in the tumor microenvironment. However, little is known regarding how these molecules affect immune cells in patients with lung cancer. We demonstrated for the first time that overexpression of endothelial adhesion molecules and cellular barrier molecule genes was linked to differential infiltration of particular immune cells in non-small cell lung cancer. Overexpression of endothelial adhesion molecule genes is associated with significantly lower infiltration of activated CD4 and CD8 T-cells, but higher infiltration of activated B-cells and regulatory T-cells. In contrast, overexpression of desmosome genes was correlated with significantly higher infiltration of activated CD4 and CD8 T-cells, but lower infiltration of activated B-cells and regulatory T-cells in lung adenocarcinoma. This inverse relation of immune cells aligns with previous studies of tumor-infiltrating B-cells inhibiting T-cell activation. Although overexpression of endothelial adhesion molecule or cellular barrier molecule genes alone was not predictive of overall survival in our sample, these genetic signatures may serve as biomarkers of immune exclusion, or resistance to T-cell mediated immunotherapy.

Targeting melanoma stem cells with the Vitamin E derivative δ-tocotrienol

The prognosis of metastatic melanoma is very poor, due to the development of drug resistance. Cancer stem cells (CSCs) may play a crucial role in this mechanism, contributing to disease relapse. We first characterized CSCs in melanoma cell lines. We observed that A375 (but not BLM) cells are able to form melanospheres and show CSCs traits: expression of the pluripotency markers SOX2 and KLF4, higher invasiveness and tumor formation capability in vivo with respect to parental adherent cells. We also showed that a subpopulation of autofluorescent cells expressing the ABCG2 stem cell marker is present in the A375 spheroid culture. Based on these data, we investigated whether δ-TT might target melanoma CSCs. We demonstrated that melanoma cells escaping the antitumor activity of δ-TT are completely devoid of the ability to form melanospheres. In contrast, cells that escaped vemurafenib treatment show a higher ability to form melanospheres than control cells. δ-TT also induced disaggregation of A375 melanospheres and reduced the spheroidogenic ability of sphere-derived cells, reducing the expression of the ABCG2 marker. These data demonstrate that δ-TT exerts its antitumor activity by targeting the CSC subpopulation of A375 melanoma cells and might represent a novel chemopreventive/therapeutic strategy against melanoma.

Immune checkpoint inhibitors in neuroendocrine tumors: A single institution experience with review of literature

This unique case series and review of literature suggests that immune checkpoint inhibitors may have clinical activity in neuroendocrine tumors.

Objective

Summarize advances of immuno-oncology in neuroendocrine tumors with the help of a case series.

Design

Case series and review of literature.

Intervention or Exposure

The patients were treated with immune checkpoint inhibitors (pembrolizumab or nivolumab).

Main Outcomes and Measuress

Life expectancy, quality of life, disease progression.

Results

Maximum durable response of 16 months in one of the patients so far. All patients showed improvement in quality of life before disease progression. Two out of four are still on therapy. None of the patients experienced immune checkpoint inhibitor associated side-effects. All patients had failed standard of care therapy prior to the initiation of immune checkpoint inhibitors and were on the verge of hospice.

Conclusions

Immune checkpoint inhibitors have revolutionized cancer management and the last 5 years have seen a rapid expansion in the indications for this class of drug. Neuroendocrine tumors, unfortunately, have been slow to catch on to the immuno-oncology, partly due to difficulties in establishing relevant preclinical neuroendocrine tumors models for immune-oncology studies. In this manuscript, we review the current status of immunotherapy in neuroendocrine tumors.

Imaging Features of Toxicities by Immune Checkpoint Inhibitors in Cancer Therapy

Purpose of review

With the increasing use of immune checkpoint inhibitors in cancer therapy radiographic profiling of frequent and serious immune-related adverse events (irAEs) becomes more relevant. This article reviews imaging features of irAEs induced by the anti-CTLA-4 and anti-PD-1 antibodies ipilimumab, nivolumab and pembrolizumab.

Recent findings

Important radiological manifestations are immune-related colitis, hepatitis, pancreatitis, hypophysitis, pneumonitis, arthritis and sarcoid-like lymphadenopathy. Typical imaging features are summarized and compared with other relevant differential diagnoses.

Summary

Early diagnosis and appropriate therapeutic decisions are required for a successful treatment of irAEs. In addition to staging and follow-up imaging, identification and monitoring of adverse events becomes an important radiologic aspect in oncologic care.