Uncoupling therapeutic from immunotherapy-related adverse effects for safer and effective anti-CTLA-4 antibodies in CTLA4 humanized mice

A novel mouse model for checkpoint inhibitor-induced adverse events

Immune checkpoint inhibitors have demonstrated significant efficacy in the treatment of a variety of cancers, however their therapeutic potential is limited by abstruse immune related adverse events. Currently, no robust animal model exists of checkpoint inhibitor-induced adverse events. Establishing such a model will improve our mechanistic understanding of this process, which in turn will inform design of improved therapies. We developed a mouse model to determine inflammatory toxicities in response to dual checkpoint blockade in the presence of syngeneic tumors. Mice from susceptible genetic backgrounds received intraperitoneal injections of anti-mouse PD-1 and CTLA-4 antibodies. The mice were monitored for weight loss and histologic evidence of inflammation. Blood was collected for basic metabolic panels and titers of anti-nuclear antibodies. In parallel, mice were also treated with prednisolone, which is commonly used to treat immune related adverse events among cancer patients. Among all the genetic backgrounds, B6/lpr mice treated with anti-CTLA-4 and anti-PD-1 antibodies developed more substantial hepatitis, pancreatitis, colitis, and pneumonitis characterized by organ infiltration of immune cells. Mice that developed tissue infiltration demonstrated high serum levels of glucose and high titers of anti-nuclear antibodies. Finally, while administration of prednisolone prevented the development of the inflammatory adverse events, it also abrogated the protective anti-tumor effect of the checkout inhibitors. Genetic background and treatment modalities jointly modified the inflammatory adverse events in tumor bearing mice, suggesting a complex mechanism for checkpoint inhibitor-related inflammation. Future studies will assess additional genetic susceptibility factors and will examine possible contributions from the administration of other anti-inflammatory drugs.

Immune Checkpoint Inhibitors: Cardiotoxicity in Pre-clinical Models and Clinical Studies

Since the approval of the first immune checkpoint inhibitor (ICI) 9 years ago, ICI-therapy have revolutionized cancer treatment. Lately, antibodies blocking the interaction of programmed cell death protein (PD-1) and ligand (PD-L1) are gaining momentum as a cancer treatment, with multiple agents and cancer types being recently approved for treatment by the US Food and Drug Administration (FDA). Unfortunately, immunotherapy often leads to a wide range of immune related adverse events (IRAEs), including several severe cardiac effects and most notably myocarditis. While increased attention has been drawn to these side effects, including publication of multiple clinical observational data, the underlying mechanisms are unknown. In the event of IRAEs, the most widely utilized clinical solution is administration of high dose corticosteroids and in severe cases, discontinuation of these ICIs. This is detrimental as these therapies are often the last line of treatment options for many types of advanced cancer. In this review, we have systematically described the pathophysiology of the PD-1/PD-L1 axis (including a historical perspective) and cardiac effects in pre-clinical models, clinical trials, autoimmune mechanisms, and immunotherapy in combination with other cancer treatments. We have also reviewed the current challenges in the diagnosis of cardiac events and future directions in the field. In conclusion, this review will delve into this expanding field of cancer immunotherapy and the emerging adverse effects that should be quickly detected and prevented.

Efficacy and immune-related adverse event associations in avelumab-treated patients

BACKGROUND

Adverse events (AEs) of special interest that arise during treatment with immune checkpoint inhibitors, including immune-related AEs (irAEs), have been reported to be associated with improved clinical outcomes. We analyzed patients treated with avelumab from the JAVELIN Solid Tumor and Merkel 200 trials, examining the association between AEs and efficacy while adjusting for confounding factors such as treatment duration and event order.

METHODS

We analyzed efficacy and safety data from 1783 patients treated with the programmed death ligand 1 inhibitor avelumab who were enrolled in expansion cohorts of the JAVELIN Solid Tumor and Merkel 200 trials. To analyze the association between irAEs and efficacy with regard to survival, we used a time-dependent Cox model with time-varying indicators for irAEs, as well as multistate models that accounted for competing risks and time inhomogeneity.

RESULTS

295 patients (16.5%) experienced irAEs and 454 patients (25.5%) experienced infusion-related reactions. There was a reduced risk of death in patients who experienced irAEs compared with those who did not (HR 0.71, 95% CI 0.59 to 0.85) using the time-dependent Cox model. The multistate model did not suggest that the occurrence of irAEs could predict response; however, it predicted a higher chance of irAEs occurring after a response. No association was observed between response and infusion-related reactions.

CONCLUSIONS

Patients who experience irAEs showed improved survival. Although irAEs are not predictors for response to immune checkpoint inhibitors, increased vigilance for irAEs is needed after treatment with avelumab.

TRIAL REGISTRATION NUMBERS

NCT01772004 and NCT02155647.

Uncoupling Therapeutic Efficacy from Immune-Related Adverse Events in Immune Checkpoint Blockade

Immunotherapy with monoclonal antibodies targeting immune checkpoint molecules, including programmed death-1 (PD-1), PD ligand-1 (PD-L1), and cytotoxic T-lymphocyte-associated antigen (CTLA)-4, has become prominent in the treatment of many types of cancer. However, a significant number of patients treated with immune checkpoint inhibitors (ICIs) develop immune-related adverse events (irAEs). irAEs can affect any organ system, and although most are clinically manageable, irAEs can result in mortality or long-term morbidity. Factors that can predict irAEs remain elusive. Understanding the etiology of ICI-induced irAEs and ways to limit these adverse events are needed. In this review, we provide basic science and clinical insights on the mechanisms responsible for ICI efficacy and ICI-induced irAEs. We further provide insights into approaches that may uncouple irAEs from the ability of ICIs to kill tumor cells.

Evidences of CTLA-4 and PD-1 Blocking Agents-Induced Cardiotoxicity in Cellular and Preclinical Models

Background: Several strategies based on immune checkpoint inhibitors (ICIs) have been developed for cancer therapy, opening to advantages in cancer outcomes. However, several ICI-induced side effects have emerged in these patients, especially a rare but clinically significant cardiotoxicity with high rate of mortality. We studied the cytotoxic and pro-inflammatory properties of Ipilimumab and Nivolumab, the underlying pathways and cytokine storm involved. Methods: Co-cultures of human cardiomyocytes and lymphocytes were exposed to Ipilimumab or Nivolumab; cell viability and expression of leukotrienes, NLRP3, MyD88, and p65/NF-kB were performed. C57 mice were treated with Ipilimumab (15 mg/kg); analysis of fractional shortening, ejection fraction, radial and longitudinal strain were made before and after treatments through 2D-echocardiography. Expression of NLRP3, MyD88, p65/NF-kB, and 12 cytokines were analyzed in murine myocardium. Results: Nivolumab and Ipilimumab exert effective anticancer, but also significant cardiotoxic effects in co-cultures of lymphocytes and tumor or cardiac cells. Both ICIs increased NLRP3, MyD88, and p65/NF-kB expression compared to untreated cells, however, the most pro-inflammatory and cardiotoxic effects were seen after exposure to Ipilimumab. Mice treated with Ipilimumab showed a significant decrease in fractional shortening and radial strain with respect to untreated mice, coupled with a significant increase in myocardial expression of NLRP3, MyD88, and several interleukins. Conclusions: Nivolumab and Ipilimumab exert cytotoxic effects mediated by the NLRP3/IL-1β and MyD88 pathways, leading to pro-inflammatory cytokine storm in heart tissue.

Molecular Markers of Regulatory T Cells in Cancer Immunotherapy with Special Focus on Acute Myeloid Leukemia (AML) - A Systematic Review

The next-generation immunotherapy can only be effective if researchers have an in-depth understanding of the function and regulation of Treg cells in antitumor immunity combined with the discovery of new immunity targets. This can enhance clinical efficacy of future and novel therapies and reduces any adverse reactions arising from the latter. This review discusses tumor treatment strategies using regulatory T (Treg) cell therapy in a Tumor Microenvironment (TME). It also discusses factors affecting TME instability as well as relevant treatments to prevent future immune disorders. It is prognosticated that PD-1 inhibitors are risky and their adverse effects should be taken into account when they are administered to treat Acute Myeloid Leukemia (AML), lung adenocarcinoma, and prostate adenocarcinoma. In contrast, Treg molecular markers FoxP3 and CD25 analyzed here have stronger expression in almost all kinds of cancers compared with normal people. However, CD25 inhibitors are more effective compared to FoxP3 inhibitors, especially in combination with TGF-β blockade, in predicting patient survival. According to the data obtained from the Cancer Genome Atlas, we then concentrate on AML immunotherapy and discuss different therapeutic strategies including anti-CD25/IL-2, anti-CTLA-4, anti-IDO, antityrosine kinase receptor, and anti-PI3K therapies and highlight the recent advances and clinical achievements in AML immunotherapy. In order to prognosticate the risk and adverse effects of key target inhibitors (namely against CTLA-4, FoxP3, CD25, and PD-1), we finally analyzed and compared the Cancer Genome Atlas derived from ten common cancers. This review shows that Treg cells are strongly increased in AML and the comparative review of key markers shows that Tregbased immunotherapy is not effective for all kinds of cancer. Therefore, blocking CD25(+)FoxP3(+) Treg cells is suggested in AML more than other kinds of cancer; meanwhile, Treg markers studied in other cancers have also great lessons for AML immunotherapy.

Improving safety of cancer immunotherapy via delivery technology

Breakthroughs in molecular mechanisms underlying immune-suppressive tumor microenvironment and paradigm shifts in the cancer-immunity response cycle have profoundly changed the landscape of cancer immunotherapy. However, one of the challenges is to mitigate the serious side effects caused by systemic autoimmunity and autoinflammatory responses following immunotherapy. Thus, restraining the activation of the immune system in healthy tissues is highly desirable to address this problem. Bioengineering and delivery technologies provide a solution to the issue. In this Review, we first introduce immune-related adverse effects of main immunotherapies and the underlying mechanisms, summarize strategies of designingde bioengineering and delivery systems to reduce their immunotoxicities, and highlight the importance of the development of immunotoxicity-related animal models.

The association between monocytic myeloid-derived suppressor cells levels and the anti-tumor efficacy of anti-PD-1 therapy in NSCLC patients

Monocytic myeloid-derived suppressor cells (M-MDSCs), granulocytic MDSC (G-MDSCs) and regulatory T cells (Tregs) inhibit adaptive anti-tumor immunity and undermine the efficacy of anti-PD-1 therapy. However, the impact of anti-PD-1 treatment on these immunosuppressive cells has not been clearly defined in non-small cell lung cancer (NSCLC). In this retrospective study, 27 advanced NSCLC patients were divided into partial response (PR), stable disease (SD), and progressive disease (PD) groups. The impact of anti-PD-1 therapy on circulating Tregs, G-MDSCs, and M-MDSCs was assessed by flow cytometer. Here, we found that anti-PD-1 treatment boosted circulating Tregs levels, which presented the most remarkable augment during the first two therapeutic cycles, in NSCLC patients. In contrast, anti-PD-1 therapy did not overall change G-MDSCs and M-MDSCs levels. However, the PR group had a higher baseline level of M-MDSCs, which exhibited a significant decrease after the first cycle of anti-PD-1 treatment. Besides, M-MDSCs levels in the PR group were maintained at a low level in the following therapeutic cycles. Consistently, Tregs levels robustly increased in the syngeneic tumor model after anti-mouse PD-1 Ab treatment. Accordingly, M-MDSCs neutralization by anti-mouse ly6c Ab enhanced the anti-tumor efficacy of anti-PD-1 therapy in mice. Finally, the decreased M-MDSCs levels were associated with the enhanced effector CD8⁺ T cells expansion in the PR group and mice. In conclusion, anti-PD-1 therapy upregulates Tregs levels in NSCLC patients, and the M-MDSC levels are associated with the anti-tumor efficacy of anti-PD-1 treatment. Neutralization of M-MDSCs may be a promising option to augment anti-PD-1 therapy efficacy in NSCLC.

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Anti-PD-1 therapy upregulates Tregs levels in NSCLC patients and mouse model.

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M-MDSCs exhibit a significant decrease in the PR group after anti-PD-1 therapy.

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M-MDSCs neutralization augments anti-PD-1 efficacy in mouse model.

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The increased effector CD8⁺ T cells are associated with the better anti-PD-1 efficacy in the PR group and mouse model.

Advances in Therapeutic Targeting of Cancer Stem Cells within the Tumor Microenvironment: An Updated Review

Despite great strides being achieved in improving cancer patients' outcomes through better therapies and combinatorial treatment, several hurdles still remain due to therapy resistance, cancer recurrence and metastasis. Drug resistance culminating in relapse continues to be associated with fatal disease. The cancer stem cell theory posits that tumors are driven by specialized cancer cells called cancer stem cells (CSCs). CSCs are a subpopulation of cancer cells known to be resistant to therapy and cause metastasis. Whilst the debate on whether CSCs are the origins of the primary tumor rages on, CSCs have been further characterized in many cancers with data illustrating that CSCs display great abilities to self-renew, resist therapies due to enhanced epithelial to mesenchymal (EMT) properties, enhanced expression of ATP-binding cassette (ABC) membrane transporters, activation of several survival signaling pathways and increased immune evasion as well as DNA repair mechanisms. CSCs also display great heterogeneity with the consequential lack of specific CSC markers presenting a great challenge to their targeting. In this updated review we revisit CSCs within the tumor microenvironment (TME) and present novel treatment strategies targeting CSCs. These promising strategies include targeting CSCs-specific properties using small molecule inhibitors, immunotherapy, microRNA mediated inhibitors, epigenetic methods as well as targeting CSC niche-microenvironmental factors and differentiation. Lastly, we present recent clinical trials undertaken to try to turn the tide against cancer by targeting CSC-associated drug resistance and metastasis.

Re-education of the Tumor Microenvironment With Targeted Therapies and Immunotherapies

The clinical success of cancer immunotherapies targeting PD-1 and CTLA-4 has ignited a substantial research effort to improve our understanding of tumor immunity. Recent studies have revealed that the immune contexture of a tumor influences therapeutic response and survival benefit for cancer patients. Identifying treatment modalities that limit immunosuppression, relieve T cell exhaustion, and potentiate effector functions in the tumor microenvironment (TME) is of much interest. In particular, combinatorial therapeutic approaches that re-educate the TME by limiting the accumulation of immunosuppressive immune cells, such as Foxp3 regulatory T cells (Tregs) and tumor-associated macrophages (TAMs), while promoting CD8+ and CD4+ effector T cell activity is critical. Here, we review key approaches to target these immunosuppressive immune cell subsets and signaling molecules and define the impact of these changes to the tumor milieu. We will highlight the preclinical and clinical evidence for their ability to improve anti-tumor immune responses as well as strategies and challenges for their implementation. Together, this review will provide understanding of therapeutic approaches to efficiently shape the TME and reinvigorate the immune response against cancer.

Regulatory T cells in tumor microenvironment: new mechanisms, potential therapeutic strategies and future prospects

Regulatory T cells (Tregs) characterized by the expression of the master transcription factor forkhead box protein p3 (Foxp3) suppress anticancer immunity, thereby hindering protective immunosurveillance of tumours and hampering effective antitumour immune responses in tumour-bearing hosts, constitute a current research hotspot in the field. However, Tregs are also essential for the maintenance of the immune tolerance of the body and share many molecular signalling pathways with conventional T cells, including cytotoxic T cells, the primary mediators of tumour immunity. Hence, the inability to specifically target and neutralize Tregs in the tumour microenvironment without globally compromising self-tolerance poses a significant challenge. Here, we review recent advances in characterizing tumour-infiltrating Tregs with a focus on the functional roles of costimulatory and inhibitory receptors in Tregs, evaluate their potential as clinical targets, and systematically summarize their roles in potential treatment strategies. Also, we propose modalities to integrate our increasing knowledge on Tregs phenotype and function for the rational design of checkpoint inhibitor-based combination therapies. Finally, we propose possible treatment strategies that can be used to develop Treg-targeted therapies.

Hypoproteinemia being a manifestation of immunotherapy-related liver dysfunction

Immunotherapy has changed the pattern of treatment in cancer. The interaction between programmed death-1 (PD-1) and programmed death-ligand 1 (PD-L1) inhibits the activation of T cells, and PD-1/PD-L1 inhibitors can increase the immune response to cancer cells by inducing the immune cells, which has become an important clinical method to treat cancer. However, the alteration in the activation of T cells might lead to misidentification between the body's own cells and tumor cells and induce immune-related adverse events (IRAEs), such as pneumonitis, liver dysfunction, rash, colitis, nephritis, and endocrinopathies. And the IRAEs might lead to serious consequences. Studies have reported that PD-1/PD-L1 inhibitor-related hepatotoxicity is one of these adverse events. Most of the studies reported that hepatitis resulting from PD-1 inhibitor was manifested as elevated liver enzymes and bilirubin. Quite a few patients experienced lower degree of hepatotoxicity treated with checkpoint inhibitors, which indicated that it was necessary to focus on immunotherapy-related liver dysfunction. Here, we report a case of immunotherapy-related liver dysfunction with hypoproteinemia as the first manifestation under the treatment of PD-1 inhibitors combined with chemotherapy. This case suggests that hypoproteinemia was one of the manifestations of immunotherapy-related liver dysfunction, which helps us better understand the immunotherapy-related disease.

Bibliometric analysis of personalized humanized mouse and Drosophila models for effective combinational therapy in cancer patients

Research performed using model organisms such as mice and the fruit fly, Drosophila melanogaster has significantly enhanced our knowledge about cancer biology and the fundamental processes of cancer. This is because the major biological properties and genes associated with cancer including signaling pathways, oncogenes, tumor suppressors, and other regulators of cell growth and proliferation are evolutionary conserved. This review provides bibliometric analysis of research productivity, and performance of authors, institutions, countries, and journals associated with personalized animal cancer models, focussing on the role of Drosophila in cancer research, thus highlighting emerging trends in the field. A total of 1469 and 2672 original articles and reviews for Drosophila cancer model and patient-derived xenograft (PDX) respectively, were retrieved from the Scopus database and the most cited papers were thoroughly analyzed. Our analysis indicates a steadily increasing productivity of the animal models and especially of mouse models in cancer research. In addition to the many different systems that address almost all aspects of tumor research in humanized animal models, a trend towards using tailored screening platforms with Drosophila models in particular will become widespread in the future. Having Drosophila models that recapitulate major genetic aspects of a given tumor will enable the development and validation of novel therapeutic strategies for specific cancers, and provide a platform for screening small molecule inhibitors and other anti-tumor compounds. The combination of Drosophila cancer models and mouse PDX models particularly is highly promising and should be one of the major research strategies the future.

Immunotherapies and Metastatic Cancers: Understanding Utility and Predictivity of Human Immune Cell Engrafted Mice in Preclinical Drug Development

Metastases cause high mortality in several cancers and immunotherapies are expected to be effective in the prevention and treatment of metastatic disease. However, only a minority of patients benefit from immunotherapies. This creates a need for novel therapies that are efficacious regardless of the cancer types and metastatic environments they are growing in. Preclinical immuno-oncology models for studying metastases have long been limited to syngeneic or carcinogenesis-inducible models that have murine cancer and immune cells. However, the translational power of these models has been questioned. Interactions between tumor and immune cells are often species-specific and regulated by different cytokines in mice and humans. For increased translational power, mice engrafted with functional parts of human immune system have been developed. These humanized mice are utilized to advance understanding the role of immune cells in the metastatic process, but increasingly also to study the efficacy and safety of novel immunotherapies. From these aspects, this review will discuss the role of immune cells in the metastatic process and the utility of humanized mouse models in immuno-oncology research for metastatic cancers, covering several models from the perspective of efficacy and safety of immunotherapies.

Targeting Inhibition of Foxp3 by MMP2/9 Sensitive Short Peptide Linked P60 Fusion Protein 6(P60-MMPs) to Enhance Antitumor Immunity

Regulatory T-cells (Tregs) play an important role in tumor immunosuppressive network, thus Tregs-targeted strategy is expected to enhance antitumor immunity and improve the effect of immunotherapy. Short peptide P60 can bind to the forkhead box protein P3 (Foxp3), a crucial transcriptional regulator for the development and inhibitory function of Tregs, and inhibit Foxp3 nuclear translocation in Tregs. However, its treatment effect in cancer is limited due to nonspecificity. Therefore, realizing the specific delivery of P60 in tumor microenvironment will greatly facilitate its Treg-suppressing effect for tumor therapeutics. Herein, utilizing the unique matrix metallase protease 2/9 (MMP2/9) overexpressing feature in tumor tissues, a fusion protein 6(P60-MMPs) containing six segments of P60 linked by MMP2/9-sensitive peptides is constructed for antitumor targeting immunotherapy. The fusion protein 6(P60-MMPs) specifically degrades into short peptide P60 in tumor, and then binds to Foxp3 to inhibit Foxp3 nuclear translocation in Tregs, thus impairing Tregs' activity. This fusion protein efficiently inhibits murine breast cancer 4T1 transplanted tumor growth and decreases lung metastasis through down-regulating tumor-infiltrated Tregs and up-regulating CD8⁺ T cells in tumor tissue. The study develops a Treg-targeted anticancer fusion protein with effective therapeutic activity, suggesting its potential in clinical translation.

Double immune checkpoint blockade in advanced NSCLC

Immunotherapy-based options for patients with advanced non-small cell lung cancer (NSCLC) are increasing at an unprecedented pace, carrying the promise to prolong survival of this deadly disease. To maximize responses and extend benefit to a larger portion of patients, immunotherapy combination strategies are currently under investigation, with chemo-immunotherapy already in use. Combinations of programmed death-1/ligand-1 (PD-1/L1) and cytotoxic T lymphocytes antigen-4 (CTLA-4) were developed with the rationale of targeting complementary pathways involved in T cell activation, and already showed to be highly active in other malignancies. Recently, the phase III Checkmate 227 trial showed that combination of nivolumab and ipilimumab provided survival benefit in untreated advanced NSCLC patients. However, accurate patients' selection and appropriate sequencing of different immunotherapy-based approaches remain unsolved. In this review, we provide an overview of the currently available evidence on double immune checkpoint inhibition (ICI) for NSCLC treatment and discuss current issues and future perspectives.

How to select IgG subclasses in developing anti-tumor therapeutic antibodies

The intact antibody of human immunoglobulin (IgG) is composed of the fragment for antigen binding (Fab) and the crystallizable fragment (Fc) for binding of Fcγ receptors. Among the four subclasses of human IgG (IgG1, IgG2, IgG3, IgG4), which differ in their constant regions, particularly in their hinges and CH2 domains, IgG1 has the highest FcγR-binding affinity, followed by IgG3, IgG2, and IgG4. As a result, different subclasses have different effector functions such as antibody-dependent cell-mediated cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP). Fcγ receptors include six subtypes (FcγRI, FcγRIIA, FcγRIIB, FcγRIIC, FcγRIIIA, FcγRIIIB) which differ in cellular distribution, binding affinity to Fc, and the resulting biological activity. Therefore, when developing anti-tumor therapeutic antibodies, including single-targeted antibodies, bi-specific antibodies (BsAbs), and antibody-drug conjugates (ADCs), many factors, such as target biology, cellular distribution of the targets, the environments of particular tumor types, as well as the proposed mechanism of action (MOA), must be taken into consideration. This review outlines fundamental strategies that are required to select IgG subclasses in developing anti-tumor therapeutic antibodies.

IL36 Cooperates With Anti-CTLA-4 mAbs to Facilitate Antitumor Immune Responses

Despite the great impact on long-term survival of some cancer patients, the immune checkpoint blockade (ICB) therapy is limited by its low response rates for most cancers. There is a pressing need for novel combination immunotherapies that overcome the resistance to current ICB therapies. Cytokines play a pivotal role in tumor immunotherapy by helping initiating and driving antitumor immune responses. Here, we demonstrated that, besides conventional CD4⁺ and CD8⁺ T cells, IL36 surprisingly increased the number of tumor-infiltrating regulatory T (Treg) cells in vivo and enhanced proliferation of Tregs in vitro. Administration of CTLA-4 monoclonal antibodies (mAbs) strongly enhanced IL36-stimulated antitumor activities through depletion of Tregs. In addition, a cancer gene therapy using the IL36-loaded nanoparticles in combination with CTLA-4 mAbs additively reduced lung metastasis of breast tumor cells. We further showed that the combined therapy of CTLA-4 mAbs and IL36 led to an increase in proliferation and IFN-γ production by CD4⁺ and CD8⁺ T cells when compared to single therapy with CTLA-4 mAbs or IL36. Collectively, our findings demonstrated a new combination therapy that could improve the clinical response to ICB immunotherapy for cancer.

Future Challenges in Cancer Resistance to Immunotherapy

Cancer immunotherapies, including checkpoint inhibitors, adoptive T cell transfer and therapeutic cancer vaccines, have shown promising response rates in clinical trials. Unfortunately, there is an increasing number of patients in which initially regressing tumors start to regrow due to an immunotherapy-driven acquired resistance. Studies on the underlying mechanisms reveal that these can be similar to well-known tumor intrinsic and extrinsic primary resistance factors that precluded the majority of patients from responding to immunotherapy in the first place. Here, we discuss primary and secondary immune resistance and point at strategies to identify potential new mechanisms of immune evasion. Ultimately, this may lead to improved immunotherapy strategies with improved clinical outcomes.

Development of bispecific antibodies in China: overview and prospects

A bispecific antibody (bsAb) can simultaneously bind two different epitopes or antigens, allowing for multiple mechanistic functions with synergistic effects. BsAbs have attracted significant scientific attentions and efforts towards their development as drugs for cancers. There are 21 bsAbs currently undergoing clinical trials in China. Here, we review their platform technologies, expression and production, and biological activities and bioassay of these bsAbs, and summarize their structural formats and mechanisms of actions. T-cell redirection and checkpoint inhibition are two main mechanisms of the bsAbs that we discuss in detail. Furthermore, we provide our perspective on the future of bsAb development in China, including CD3-bsAbs for solid tumors and related cytokine release syndromes, expression and chemistry, manufacturing and controls, clinical development, and immunogenicity.

Sensitizing the Tumor Microenvironment to Immune Checkpoint Therapy

Immune checkpoint blockade (ICB) has revolutionized cancer treatment, providing remarkable clinical responses in some patients. However, the majority of patients do not respond. It is therefore crucial both to identify predictive biomarkers of response and to increase the response rates to immune checkpoint therapy. In this review we explore the current literature about the predictive characteristics of the tumor microenvironment and discuss therapeutic approaches that aim to change this toward a milieu that is conducive to response. We propose a personalized biomarker-based adaptive approach to immunotherapy, whereby a sensitizing therapy is tailored to the patient's specific tumor microenvironment, followed by on-treatment verification of a change in the targeted biomarker, followed by immune checkpoint therapy. By incorporating detailed knowledge of the immunological tumor microenvironment, we may be able to sensitize currently non-responsive tumors to respond to immune checkpoint therapy.

Challenges of combination therapy with immune checkpoint inhibitors for hepatocellular carcinoma

Immune checkpoint inhibitor (ICI) therapy targeting anti-programmed cell death-1 (anti-PD-1) or its ligand (anti-PD-L1) is the backbone of numerous combination regimens aimed at improving the objective response and survival of patients with hepatocellular carcinoma (HCC). Clinical trials of immuno-oncology regimens in other cancer types have shed light on issues of study design, including how to choose candidate regimens based on early-phase trial results, statistical considerations in trials with multiple primary endpoints, and the importance of predictive biomarkers. In this review, the updated data from early-phase trials of combination immunotherapy for HCC are summarised. Since the most extensively tested combination regimens for advanced HCC comprise anti-PD-1/anti-PD-L1 agents plus antiangiogenic agents, the relative benefit and antitumor mechanism of antiangiogenic multikinase inhibitors versus specific VEGF/VEGFR inhibitors are discussed. Other critical issues in the development of combination immunotherapy, including optimal management of immune-related adverse events and the value of ICI therapy in combination with locoregional treatment for HCC, are also explored.

Mechanism- and Immune Landscape-Based Ranking of Therapeutic Responsiveness of 22 Major Human Cancers to Next Generation Anti-CTLA-4 Antibodies

Background: CTLA-4 was the first immune checkpoint targeted for cancer therapy and the first target validated by the FDA (Food and Drug Administration) after approval of the anti-CTLA-4 antibody, Ipilimumab. However, clinical response rates to anti-CTLA-4 antibodies are lower while the rates of immunotherapy-related adverse events (irAE) are higher than with anti-PD-1 antibodies. As a result, the effort to target CTLA-4 for cancer immunotherapy has stagnated. To reinvigorate CTLA-4-targeted immunotherapy, we and others have reported that rather than blocking CTLA-4 interaction with its cognate targets, CD80 and CD86, anti-CTLA-4 antibodies achieve their therapeutic responses through selective depletion of regulatory T cells in the tumor microenvironment. Accordingly, we have developed a new generation of anti-CTLA-4 antibodies with reduced irAE and enhanced antibody-dependent cell-mediated cytotoxicity/phagocytosis (ADCC/ADCP). A major unresolved issue is how to select appropriate cancer types for future clinical development. Methods: We generated a landscape of the immune tumor microenvironment from RNAseq and genomic data of 7279 independent cancer samples belonging to 22 cancer types from The Cancer Genomics Atlas (TCGA) database. Based primarily on genomic and RNAseq data from pre-treatment clinical samples of melanoma patients who were later identified as responders and nonresponders to the anti-CTLA-4 antibody Ipilimumab, we identified 5 ranking components of responsiveness to anti-CTLA-4, including CTLA-4 gene expression, ADCC potential, mutation burden, as well as gene enrichment and cellular composition that favor CTLA-4 responsiveness. The total ranking number was calculated by the sum of 5 independent partitioning values, each comprised of 1–3 components. Results: Our analyses predict metastatic melanoma as the most responsive cancer, as expected. Surprisingly, non-small cell lung carcinoma (NSCLC) is predicted to be highly responsive to anti-CTLA-4 antibodies. Single-cell RNAseq analysis and flow cytometry of human NSCLC-infiltrating T cells supports the potential of anti-CTLA-4 antibodies to selectively deplete intratumoral Treg. Conclusions: Our in silico and experimental analyses suggest that non-small cell lung carcinoma will likely respond to a new generation of anti-CTLA-4 monoclonal antibodies. Our approach provides an objective ranking of the sensitivity of human cancers to anti-CTLA-4 antibodies. The comprehensive ranking of major cancer types provides a roadmap for clinical development of the next generation of anti-CTLA-4 antibodies.

Preserving the CTLA-4 Checkpoint for Safer and More Effective Cancer Immunotherapy

A major paradigm in cancer immunotherapy is the use of checkpoint inhibitors to break regulatory mechanisms that usually guard the host against autoimmune diseases. CTLA-4-targeting immunotherapy was the first example that helped establish this paradigm. However, the clinically tested anti-CTLA-4 antibodies exhibit suboptimal efficacy but high toxicity. Recent studies have demonstrated that immunotherapy-related adverse events (irAE) and the cancer immunotherapeutic effect (CITE) represent distinct and therapeutically separable activities of anti-CTLA-4 antibodies. The former is attributable to inactivation of the CTLA-4 checkpoint, while the latter is due to selective depletion of regulatory T cells (Treg) in a tumor microenvironment. Here we argue that for safer and more effective CTLA-4-targeting immune therapy, one should preserve rather than inhibit the CTLA-4 checkpoint while enhancing the efficacy and selectivity of Treg depletion in a tumor microenvironment.

CTLA-4 Immunohistochemistry and Quantitative Image Analysis for Profiling of Human Cancers

There is an important need in immuno-oncology to develop reliable immunohistochemistry (IHC) to assess the expression of CTLA-4⁺ tumor-infiltrating lymphocytes in human cancers and quantify them with image analysis (IA). We used commercial polyclonal and monoclonal antibodies and characterized three chromogenic cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) assays with suitable specificity and sensitivity for use in formalin-fixed, paraffin-embedded (FFPE) tissues. We found variable numbers of CTLA-4⁺ lymphocytes in multiple types of cancer and secondary lymphoid organs (SLOs) and other normal human tissues. Combining CTLA-4 with CD3, CD4, or CD8 by immunofluorescence showed that CTLA-4⁺ lymphocytes in SLOs and tumors were typically CD3⁺ and CD4⁺, but not CD8⁺. Individual lymphocytes expressed CTLA-4 either as primarily granular cytoplasmic staining or as excentric globular deposits. The CTLA-4/FoxP3 (forkhead box P3 protein) duplex IHC demonstrated that CTLA-4⁺/FoxP3^- lymphocytes predominated in the germinal centers of SLOs and tumor tertiary lymphoid structures (TLSs), whereas CTLA-4⁺/FoxP3⁺ lymphocytes populated the T-cell zone of SLOs and TLSs, plus tumor stroma. IA scoring was highly comparable with pathologist scoring for CTLA-4 and CTLA-4/FoxP3 assays and a FoxP3 single IHC. Our findings show that CTLA-4 IHC can be used to reliably label lymphocytes in FFPE human tissues, making it possible to investigate the role of CTLA-4 in the tumor microenvironment.

Demystifying the manipulation of host immunity, metabolism, and extraintestinal tumors by the gut microbiome

The trillions of microorganisms in the gut microbiome have attracted much attention recently owing to their sophisticated and widespread impacts on numerous aspects of host pathophysiology. Remarkable progress in large-scale sequencing and mass spectrometry has increased our understanding of the influence of the microbiome and/or its metabolites on the onset and progression of extraintestinal cancers and the efficacy of cancer immunotherapy. Given the plasticity in microbial composition and function, microbial-based therapeutic interventions, including dietary modulation, prebiotics, and probiotics, as well as fecal microbial transplantation, potentially permit the development of novel strategies for cancer therapy to improve clinical outcomes. Herein, we summarize the latest evidence on the involvement of the gut microbiome in host immunity and metabolism, the effects of the microbiome on extraintestinal cancers and the immune response, and strategies to modulate the gut microbiome, and we discuss ongoing studies and future areas of research that deserve focused research efforts.

Scientific and Regulatory Policy Committee Points to Consider*: Approaches to the Conduct and Interpretation of Vaccine Safety Studies for Clinical and Anatomic Pathologists

The design and execution of toxicology studies supporting vaccine development have some unique considerations relative to those supporting traditional small molecules and biologics. A working group of the Society of Toxicologic Pathology Scientific and Regulatory Policy Committee conducted a review of the scientific, technical, and regulatory considerations for veterinary pathologists and toxicologists related to the design and evaluation of regulatory toxicology studies supporting vaccine clinical trials. Much of the information in this document focuses on the development of prophylactic vaccines for infectious agents. Many of these considerations also apply to therapeutic vaccine development (such as vaccines directed against cancer epitopes); important differences will be identified in various sections as appropriate. The topics addressed in this Points to Consider article include regulatory guidelines for nonclinical vaccine studies, study design (including species selection), technical considerations in dosing and injection site collection, study end point evaluation, and data interpretation. The intent of this publication is to share learnings related to nonclinical studies to support vaccine development to help others as they move into this therapeutic area. [Box: see text].

Hijacking antibody-induced CTLA-4 lysosomal degradation for safer and more effective cancer immunotherapy

It remains unclear why the clinically used anti-CTLA-4 antibodies, popularly called checkpoint inhibitors, have severe immunotherapy-related adverse effects (irAEs) and yet suboptimal cancer immunotherapeutic effects (CITE). Here we report that while irAE-prone Ipilimumab and TremeIgG1 rapidly direct cell surface CTLA-4 for lysosomal degradation, the non-irAE-prone antibodies we generated, HL12 or HL32, dissociate from CTLA-4 after endocytosis and allow CTLA-4 recycling to cell surface by the LRBA-dependent mechanism. Disrupting CTLA-4 recycling results in robust CTLA-4 downregulation by all anti-CTLA-4 antibodies and confers toxicity to a non-irAE-prone anti-CTLA-4 mAb. Conversely, increasing the pH sensitivity of TremeIgG1 by introducing designed tyrosine-to-histidine mutations prevents antibody-triggered lysosomal CTLA-4 downregulation and dramatically attenuates irAE. Surprisingly, by avoiding CTLA-4 downregulation and due to their increased bioavailability, pH-sensitive anti-CTLA-4 antibodies are more effective in intratumor regulatory T-cell depletion and rejection of large established tumors. Our data establish a new paradigm for cancer research that allows for abrogating irAE while increasing CITE of anti-CTLA-4 antibodies.

Severe Relapse of Vaccine-Induced Guillain-Barré Syndrome After Treatment With Nivolumab

Cancer immunotherapy with checkpoint inhibitors may result in neuromuscular immune-related adverse reactions, including Guillain-Barré syndrome (GBS)-like disease. On the other hand, checkpoint inhibitor therapy may result in exacerbation of underlying autoimmune diseases such as myasthenia gravis and multiple sclerosis. We present a patient who developed a severe and fatal relapse of postvaccination GBS after he was treated with nivolumab, a monoclonal antibody directed to programmed death-1 (PD-1), during a GBS treatment-related fluctuation. We recommend that caution be exercised in starting treatment with PD-1 inhibitors in the acute stage or early in the recovery period of GBS.

How Does an Anti-CTLA-4 Antibody Promote Cancer Immunity?

Anti-CTLA-4 antibodies can induce lasting protection for some melanoma patients. However, their therapeutic potential is limited by significant immunotherapy-related adverse effects (irAE). Here, we argue that the therapeutic effect may be based on an agonist activity that is fundamentally distinct, and can be therapeutically differentiated, from the antagonist activity responsible for irAE.

Combination of Immunotherapy With Targeted Therapy: Theory and Practice in Metastatic Melanoma

Metastatic melanoma is the most aggressive and obstinate skin cancer with poor prognosis. Variant novel applicable regimens have emerged during the past decades intensively, while the most profound approaches are oncogene-targeted therapy and T-lymphocyte mediated immunotherapy. Although targeted therapies generated remarkable and rapid clinical responses in the majority of patients, acquired resistance was developed promptly within months leading to tumor relapse. By contrast, immunotherapies elicited long-term tumor regression. However, the overall response rate was limited. In view of the above, either targeted therapy or immunotherapy cannot elicit durable clinical responses in large range of patients. Interestingly, the advantages and limitations of these regimens happened to be complementary. An increasing number of preclinical studies and clinical trials proved a synergistic antitumor effect with the combination of targeted therapy and immunotherapy, implying a promising prospect for the treatment of metastatic melanoma. In order to achieve a better therapeutic effectiveness and reduce toxicity in patients, great efforts need to be made to illuminate multifaceted interplay between targeted therapy and immunotherapy.

Risk of dermatologic and mucosal adverse events associated with PD-1/PD-L1 inhibitors in cancer patients: A meta-analysis of randomized controlled trials

BACKGROUND

Programmed death 1 protein (PD-1) and programmed death-ligand 1 (PD-L1) inhibitors are promising cancer immunotherapy. Their dermatologic safety profiles are still poorly understood. The purpose of this article is to evaluate the incidence of selected dermatologic and mucosal adverse effects (AEs) and determine the risk of developing these adverse events associated with PD-1/PD-L1 inhibitors, compared with chemotherapy or ipilimumab.

METHODS

PubMed was searched for eligible studies (up to February 21, 2019). Only phase II and phase III randomized controlled trials (RCTs) compared with chemotherapy or ipilimumab monotherapy were included in this meta-analysis.

RESULTS

A total 11,465 patients from 18 clinical trials were included in this meta-analysis. Rash and pruritus were the most frequently reported dermatologic AE, with incidence 11.8% and 12.2% respectively. Compared with patients receiving chemotherapy, PD-1/PD-L1 inhibitor treated patients had higher risk of developing rash (RR = 1.84), pruritus (RR = 3.74) and vitiligo (RR = 9.54), and also lower risk in developing mucosal inflammation (RR = 0.26), stomatitis (RR = 0.26), and alopecia (RR = 0.03). Additionally, anti-PD1/PD-L1 drugs had similar risk of developing rash and lower risk of inducing pruritus compared to ipilimumab. In the subgroup analysis, PD-L1 inhibitor demonstrated better safety than PD-1 inhibitor in developing rash, with RR = 1.38 and RR = 2.11, respectively.

CONCLUSION

Our meta-analysis concluded that anti PD-1/PD-L1 drugs have different dermatological and mucosal safety profile compared to conventional therapy, and differences of dermatological toxicity between PD-1 and PD-L1 inhibitor warrant further investigation.

FcγR-Binding Is an Important Functional Attribute for Immune Checkpoint Antibodies in Cancer Immunotherapy

T cells play critical roles in anti-tumor immunity. Up-regulation of immune checkpoint molecules (PD-1, PD-L1, CTLA-4, TIM-3, Lag-3, TIGIT, CD73, VISTA, B7-H3) in the tumor microenvironment is an important mechanism that restrains effector T cells from the anti-tumor activity. To date, immune checkpoint antibodies have demonstrated significant clinical benefits for cancer patients treated with mono- or combination immunotherapies. However, many tumors do not respond to the treatment well, and merely blocking the immune suppression pathways by checkpoint-regulatory antibodies may not render optimal tumor growth inhibition. Binding of the antibody Fc-hinge region to Fc gamma receptors (FcγRs) has been shown to exert a profound impact on antibody function and in vivo efficacy. Investigation of immune checkpoint antibodies regarding their effector functions and impact on therapeutic efficacy has gained more attention in recent years. In this review, we discuss Fc variants of antibodies against immune checkpoint targets and the potential mechanisms of how FcγR-binding could influence the anti-tumor activity of these antibodies.

An adapted anti-CTLA4 therapeutic aimed at mitigating the toxicities of checkpoint inhibition

Antibodies that target immune checkpoint molecules, such as CTLA4, provide robust antitumor effects in a subset of patients. Unfortunately, not all patients respond to immune checkpoint inhibition, and some develop life-threatening immune-related adverse events (irAEs). The mechanisms that underlie irAEs from immune checkpoint inhibition are not fully understood, and treatment strategies are currently limited to targeting inflammatory mediators. In this issue of the JCI, Pai et al. report on their development of a modified CTLA4 antibody that shields the inner CTLA4-binding domain until the antibody is within the protease-rich tumor microenvironment. In a lymphopenic murine model reconstituted with naive CD4+ T cells, adapted anti-CTLA4 reduced the occurrence of irAEs and enhanced antitumor effects. This thought-provoking study lays the groundwork for further exploration of this adapted antibody in immunocompetent hosts and introduction of this adaptation to other immune checkpoint molecules. It also suggests that this approach may reduce the incidence of irAEs.

The Balancing Act between Cancer Immunity and Autoimmunity in Response to Immunotherapy

The explosion in novel cancer immunotherapies has resulted in extraordinary clinical successes in the treatment of multiple cancers. Checkpoint inhibitors (CPIs) that target negative regulatory molecules have become standard of care. However, with the growing use of CPIs, alone or in combination with chemotherapy, targeted therapies, or other immune modulators, a significant increase in immune-related adverse events (irAEs) has emerged. The wide-ranging and currently unpredictable spectrum of CPI-induced irAEs can lead to profound pathology and, in some cases, death. Growing evidence indicates that many irAEs are a consequence of a breakdown in self-tolerance, but the influence of genetics, the environment, and the mechanisms involved remains unclear. This review explores key questions in this emerging field, summarizing preclinical and clinical experiences with this new generation of cancer drugs, the growing understanding of the role of the immune response in mediating these toxicities, the relationship of CPI-induced autoimmunity to conventional autoimmune diseases, and insights into the mechanism of irAE development and treatment.

A comprehensive review on the role of co-signaling receptors and Treg homeostasis in autoimmunity and tumor immunity

The immune system ensures optimum T-effector (Teff) immune responses against invading microbes and tumor antigens while preventing inappropriate autoimmune responses against self-antigens with the help of T-regulatory (Treg) cells. Thus, Treg and Teff cells help maintain immune homeostasis through mutual regulation. While Tregs can contribute to tumor immune evasion by suppressing anti-tumor Teff response, loss of Treg function can result in Teff responses against self-antigens leading to autoimmune disease. Thus, loss of homeostatic balance between Teff/Treg cells is often associated with both cancer and autoimmunity. Co-stimulatory and co-inhibitory receptors, collectively known as co-signaling receptors, play an indispensable role in the regulation of Teff and Treg cell expansion and function and thus play critical roles in modulating autoimmune and anti-tumor immune responses. Over the past three decades, considerable efforts have been made to understand the biology of co-signaling receptors and their role in immune homeostasis. Mutations in co-inhibitory receptors such as CTLA4 and PD1 are associated with Treg dysfunction, and autoimmune diseases in mice and humans. On the other hand, growing tumors evade immune surveillance by exploiting co-inhibitory signaling through expression of CTLA4, PD1 and PDL-1. Immune checkpoint blockade (ICB) using anti-CTLA4 and anti-PD1 has drawn considerable attention towards co-signaling receptors in tumor immunology and created renewed interest in studying other co-signaling receptors, which until recently have not been as well studied. In addition to co-inhibitory receptors, co-stimulatory receptors like OX40, GITR and 4-1BB have also been widely implicated in immune homeostasis and T-cell stimulation, and use of agonistic antibodies against OX40, GITR and 4-1BB has been effective in causing tumor regression. Although ICB has seen unprecedented success in cancer treatment, autoimmune adverse events arising from ICB due to loss of Treg homeostasis poses a major obstacle. Herein, we comprehensively review the role of various co-stimulatory and co-inhibitory receptors in Treg biology and immune homeostasis, autoimmunity, and anti-tumor immunity. Furthermore, we discuss the autoimmune adverse events arising upon targeting these co-signaling receptors to augment anti-tumor immune responses.

Role of Adaptive and Innate Immunity in Type 2 Diabetes Mellitus

After the recognition of the essential role of the immune system in the progression of type 2 diabetes mellitus, more studies are focused on the effects produced by the abnormal differentiation of components of the immune system. In patients suffering from obesity or T2DM, there were alterations in proliferation of T cells and macrophages, and impairment in function of NK cells and B cells, which represented abnormal innate and adaptive immunity. The abnormality of either innate immunity, adaptive immunity, or both was involved and interacted with each other during the progression of T2DM. Although previous studies have revealed the functional involvement of T cells in T2DM, and the regulation of metabolism by the innate or adaptive immune system during the pathogenesis of T2DM, there has been a lack of literature reviewing the relevant role of adaptive and innate immunity in the progression of T2DM. Here, we will review their relevant roles, aiming to provide new thought for the development of immunotherapy in T2DM.

Role of non-coding RNAs in cardiotoxicity of chemotherapy

The long-time paradoxical situation of non-coding RNAs (ncRNAs) has been terminated for they emerge as executive at full spectrum of gene expression and translation. More recently, it has been demonstrated that some ncRNAs apparently are associated with chemotherapy, causing cardiotoxicity, which taint long-term recovery of patients in growing body of evidence. The current review focused on up-to-date knowledge on regulation change and molecular signaling of ncRNAs, at mean time evaluate their potentials as diagnostic biomarkers or therapeutic targets to monitor and protect cardio function.

Aplastic anemia secondary to nivolumab and ipilimumab in a patient with metastatic melanoma: a case report

Background

Immune checkpoint blockade (ICB) is becoming an increasingly prevalent strategy in the clinical realm of cancer therapeutics. With more patients being administered ICB for a host of tumor types, the scope of adverse events associated with these drugs will likely grow. Here we report a case of aplastic anemia (AA) in a patient with metastatic melanoma secondary to dual ICB therapy. To our knowledge, this is only the second case of AA secondary to dual ICB in the literature, and the first to have a positive patient outcome.

Case presentation

A 51-year old male with metastatic melanoma was started on dual immune checkpoint blockade, in the form ipilimumab (3 mg/kg) and nivolumab (1 mg/kg). Two weeks following the second cycle, he presented to the emergency department with profound polypipsia, polyuria and fatigue. The patient was diagnosed with diabetic ketoacidosis secondary to immune therapy induced type-1 diabetes and was admitted to the ICU. While in hospital the patient developed a symptomatic anemia and neutropenia. A bone marrow biopsy revealed a markedly hypocellular marrow with trinlineage hypoplasia with no evidence of myelodysplasia, neoplasm or excess blasts. Flow cytometry revealed an inverted CD4⁺:CD8⁺ ratio and an absence of hematogones. Taken together the presumed etiology was AA secondary to immunotherapy. The patient was subsequently started in IV methylprednisone 70 mg/day for 8 days, followed by a prednisone taper. This intervention rectified the bicytopenia and to date the patient has shown stable blood counts.

Conclusion

With the use of ICBs becoming increasingly prevalent in the clinical arena, the number of patients presenting with immune-related adverse events will likely increase. The current case illustrates the need to be vigilant when managing cancer patients receiving ICB. The resolution of this patient’s AA with corticosteroids highlights the value of early detection and appropriate treatment of these rare immune-mediated adverse events.