VISTA antibody-loaded Fe3O4@TiO2 nanoparticles for sonodynamic therapy-synergistic immune checkpoint therapy of pancreatic cancer

Breaking the poor permeability of immune checkpoint inhibitors (ICIs) caused by the stromal barrier and reversing the immunosuppressive microenvironment are significant challenges in pancreatic cancer immunotherapy. In this study, we synthesized core-shell Fe3O4@TiO2 nanoparticles to act as carriers for loading VISTA monoclonal antibodies to form Fe3O4@TiO2@VISTAmAb (FTV). The nanoparticles are designed to target the overexpressed ICIs VISTA in pancreatic cancer, aiming to improve magnetic resonance imaging-guided sonodynamic therapy (SDT)-facilitated immunotherapy. Laser confocal microscopy and flow cytometry results demonstrate that FTV nanoparticles are specifically recognized and phagocytosed by Panc-2 cells. In vivo experiments reveal that ultrasound-triggered TiO2 SDT can induce tumor immunogenic cell death (ICD) and recruit T-cell infiltration within the tumor microenvironment by releasing damage-associated molecular patterns (DAMPs). Furthermore, ultrasound loosens the dense fibrous stroma surrounding the pancreatic tumor and increases vascular density, facilitating immune therapeutic efficiency. In summary, our study demonstrates that FTV nanoparticles hold great promise for synergistic SDT and immunotherapy in pancreatic cancer.

Viewing the immune checkpoint VISTA: landscape and outcomes across cancers

BACKGROUND

Optimizing immune checkpoint inhibitor (ICI) therapy may require identification of co-targetable checkpoint pathways via immune profiling. Herein, we analyzed the transcriptomic expression and clinical correlates of V-domain immunoglobulin suppressor of T-cell activation (VISTA), a promising targetable checkpoint.

PATIENTS AND METHODS

RNA sequencing was carried out on 514 tissues reflecting diverse advanced/metastatic cancers. Expression of eight immune checkpoint markers [lymphocyte-activation gene 3 (LAG-3), tumor necrosis factor receptor superfamily 14 (TNFRSF14), programmed cell death protein 1 (PD-1), programmed death-ligand 1 (PD-L1), programmed death-ligand 2 (PD-L2), B- and T-lymphocyte attenuator (BTLA), T-cell immunoglobulin and mucin domain-containing protein 3 (TIM-3), cytotoxic T-lymphocyte antigen 4 (CTLA-4)], in addition to VISTA, was analyzed, along with clinical outcomes.

RESULTS

High VISTA RNA expression was observed in 32% of tumors (66/514) and was the most common highly expressed checkpoint among the nine assessed. High VISTA expression was independently correlated with high BTLA, TIM-3, and TNFRSF14, and with a diagnosis of pancreatic, small intestine, and stomach cancer. VISTA transcript levels did not correlate with overall survival (OS) from metastatic/advanced disease in the pan-cancer cohort or with immunotherapy outcome (progression-free survival and OS from the start of ICI) in 217 ICI-treated patients. However, in ICI-treated pancreatic cancer patients (n = 16), median OS was significantly shorter (from immunotherapy initiation) for the high- versus not-high-VISTA groups (0.28 versus 1.21 years) (P = 0.047); in contrast, VISTA levels were not correlated with OS in 36 pancreatic cancer patients who did not receive ICI.

CONCLUSION

High VISTA expression correlates with high BTLA, TIM-3, and TNFRSF14 checkpoint-related molecules and with poorer post-immunotherapy survival in pancreatic cancer, consistent with prior literature indicating that VISTA is prominently expressed on CD68+ macrophages in pancreatic cancers and requiring validation in larger prospective studies. Immunomic analysis may be important for individualized precision immunotherapy.

The Evolving Landscape of Antibody-Drug Conjugates: In Depth Analysis of Recent Research Progress

Antibody-drug conjugates (ADCs) are targeted immunoconjugate constructs that integrate the potency of cytotoxic drugs with the selectivity of monoclonal antibodies, minimizing damage to healthy cells and reducing systemic toxicity. Their design allows for higher doses of the cytotoxic drug to be administered, potentially increasing efficacy. They are currently among the most promising drug classes in oncology, with efforts to expand their application for nononcological indications and in combination therapies. Here we provide a detailed overview of the recent advances in ADC research and consider future directions and challenges in promoting this promising platform to widespread therapeutic use. We examine data from the CAS Content Collection, the largest human-curated collection of published scientific information, and analyze the publication landscape of recent research to reveal the exploration trends in published documents and to provide insights into the scientific advances in the area. We also discuss the evolution of the key concepts in the field, the major technologies, and their development pipelines with company research focuses, disease targets, development stages, and publication and investment trends. A comprehensive concept map has been created based on the documents in the CAS Content Collection. We hope that this report can serve as a useful resource for understanding the current state of knowledge in the field of ADCs and the remaining challenges to fulfill their potential.

Advances in Immunotherapy for Hepatocellular Carcinoma (HCC)

Hepatocellular carcinoma (HCC) is the second most common cause of cancer-related deaths in the world. More than half of patients with HCC present with advanced stage, and highly active systemic therapies are crucial for improving outcomes. Immune checkpoint inhibitor (ICI)-based therapies have emerged as novel therapy options for advanced HCC. Only one third of patients achieve an objective response with ICI-based therapies due to primary resistance or acquired resistance. The liver tumor microenvironment is naturally immunosuppressive, and specific mutations in cell signaling pathways allow the tumor to evade the immune response. Next, gene sequencing of the tumor tissue or circulating tumor DNA may delineate resistance mechanisms to ICI-based therapy and provide a rationale for novel combination therapies. In this review, we discuss the results of key clinical trials that have led to approval of ICI-based therapy options in advanced HCC and summarize the ongoing clinical trials. We review resistance mechanisms to ICIs and discuss how immunotherapies may be optimized based on the emerging research of tumor biomarkers and genomic alterations.

Vista of the Future: Novel Immunotherapy Based on the Human V-Set Immunoregulatory Receptor for Digestive System Tumors

While gastrointestinal tumors remain a multifactorial and prevalent group of malignancies commonly treated surgically in combination with chemotherapy and radiotherapy, advancements regarding immunotherapeutic approaches continue to occur. Entering a new era of immunotherapy focused on overcoming resistance to preceding therapies caused the emergence of new therapeutic strategies. A promising solution surfaces with a V-domain Ig suppressor of T-cell activation (VISTA), a negative regulator of a T-cell function expressed in hematopoietic cells. Due to VISTA's ability to act as both a ligand and a receptor, several therapeutic approaches can be potentially developed. A broad expression of VISTA was discovered on various tumor-growth-controlling cells, which proved to increase in specific tumor microenvironment (TME) conditions, thus serving as a rationale behind the development of new VISTA-targeting. Nevertheless, VISTA's ligands and signaling pathways are still not fully understood. The uncertain results of clinical trials suggest the need for future examining inhibitor agents for VISTA and implicating a double immunotherapeutic blockade. However, more research is needed before the breakthrough can be achieved. This review discusses perspectives and novel approaches presented in the current literature. Based on the results of the ongoing studies, VISTA might be considered a potential target in combined therapy, especially for treating gastrointestinal malignancies.

Novel technologies for applying immune checkpoint blockers

Cancer cells develop several ways to subdue the immune system among others via upregulation of inhibitory immune checkpoint (ICP) proteins. These ICPs paralyze immune effector cells and thereby enable unfettered tumor growth. Monoclonal antibodies (mAbs) that block ICPs can prevent immune exhaustion. Due to their outstanding effects, mAbs revolutionized the field of cancer immunotherapy. However, current ICP therapy regimens suffer from issues related to systemic administration of mAbs, including the onset of immune related adverse events, poor pharmacokinetics, limited tumor accessibility and immunogenicity. These drawbacks and new insights on spatiality prompted the exploration of novel administration routes for mAbs for instance peritumoral delivery. Moreover, novel ICP drug classes that are adept to novel delivery technologies were developed to circumvent the drawbacks of mAbs. We therefore review the state-of-the-art and novel delivery strategies of ICP drugs.

YPD-30, a prodrug of YPD-29B, is an oral small-molecule inhibitor targeting PD-L1 for the treatment of human cancer

PD-1 and PD-L1 antibodies have brought about extraordinary clinical benefits for cancer patients, and their indications are expanding incessantly. Currently, most PD-1/PD-L1 agents are administered intravenously, which may be uncomfortable for some cancer patients. Herein, we develop a novel oral-delivered small molecular, YPD-29B, which specifically targets human PD-L1. Our data suggested that YPD-29B could potently and selectively block the interaction between PD-L1 and PD-1, but did not inhibit any other immune checkpoints. Mechanistically, YPD-29B induced human PD-L1 dimerization and internalization, which subsequently activated T lymphocytes and therefore overcomes immunity tolerance in vitro. YDP-29B was modified as the YPD-30 prodrug to improve druggability. Using humanized mice with human PD-1 xenografts of human PD-L1 knock-in mouse MC38 cancer cells, we demonstrated that YPD-30 exhibited significant antitumor activity and was well tolerated in vivo. Taken together, our results indicate that YPD-30 serves as a promising therapeutic candidate for anti-human PD-L1 cancer immunotherapy.

Targeted Anti-Tumor Immunotherapy Using Tumor Infiltrating Cells

In the tumor microenvironment, T cells, B cells, and many other cells play important and distinct roles in anti-tumor immunotherapy. Although the immune checkpoint blockade and adoptive cell transfer can elicit durable clinical responses, only a few patients benefit from these therapies. Increased understanding of tumor-infiltrating immune cells can provide novel therapies and drugs that induce a highly specific anti-tumor immune response to certain groups of patients. Herein, the recent research progress on tumor-infiltrating B cells and T cells, including CD8+ T cells, CD4+ T cells, and exhausted T cells and their role in anti-tumor immunity, is summarized. Moreover, several anti-tumor therapy approaches are discussed based on different immune cells and their prospects for future applications in cancer treatment.

Structure-activity relationship and biological evaluation of 12 N-substituted aloperine derivatives as PD-L1 down-regulatory agents through proteasome pathway

Twenty-nine 12 N-substituted aloperine derivatives were synthesized and screened for suppression on PD-L1 expression in H460 cells, as a continuation of our work. Systematic structural modifications led to the identification of compound 6b as the most active PD-L1 modulator. Compound 6b could significantly down-regulate both constitutive and inductive PD-L1 expression in NSCLC cells, and successively enhance the cytotoxicity of co-cultured T cells against tumor cells at the concentration of 20 μM. Also, it exhibited a moderate in vivo anticancer efficacy against Lewis tumor xenograft with a stable PK and safety profile. The mechanism study indicated that 6b mediated the degradation of PD-L1 through a proteasome pathway, rather than a lysosome route. These results provided the powerful information for cancer immunotherapy of aloperine derivatives with unique endocyclic skeleton by targeting PD-L1 to activate immune cells to kill cancer cells.

SAR study of small molecule inhibitors of the programmed cell death-1/programmed cell death-ligand 1 interaction

The development of small molecule inhibitors of programmed cell death-1/programmed cell death-ligand 1 (PD-1/PD-L1) has drawn research interest for the treatment of cancer. Recently, we reported the discovery of a novel dimeric core small molecule PD-1/PD-L1 inhibitor. In an effort to discover more potent inhibitors, we further explored the dimeric core scaffold. Our investigations of the structure-activity-relationship revealed that introduction of lipophilic substituents onto one of the di-alkoxylated phenyl rings improved binding affinities to PD-L1, and inhibitory activities of PD-1/PD-L1 in cellular assays. Furthermore, conversion of the ether linker part to an olefin linker not only improved binding affinity but also led to slow dissociation binding kinetics. We also explored more potent, as well as downsized, scaffolds. Compounds bearing a linear chain in place of one of the di-alkoxylated phenyl rings exhibited good binding affinity with improved ligand efficiency (LE). Representative compounds demonstrated potent inhibitory activities of PD-1/PD-L1 in the submicromolar range in cellular assays as well as cellular function in the mixed lymphocyte reaction (MLR) assay with efficacy comparable to anti-PD-1 antibody. Our results provide applicable information for the design of more potent inhibitors targeting PD-1/PD-L1 pathway.

Inhibition of lung tumorigenesis by a small molecule CA170 targeting the immune checkpoint protein VISTA

Expressed on cells of the myeloid and lymphoid lineages, V-domain Ig Suppressor of T cell Activation (VISTA) is an emerging target for cancer immunotherapy. Blocking VISTA activates both innate and adaptive immunity to eradicate tumors in mice. Using a tripeptide small molecule antagonist of VISTA CA170, we found that it exhibited potent anticancer efficacy on carcinogen-induced mouse lung tumorigenesis. Remarkably, lung tumor development was almost completely suppressed when CA170 was combined with an MHCII-directed KRAS peptide vaccine. Flow cytometry and single-cell RNA sequencing (scRNA-seq) revealed that CA170 increased CD8+ T cell infiltration and enhanced their effector functions by decreasing the tumor infiltration of myeloid-derived suppressor cells (MDSCs) and Regulatory T (Treg) cells, while the Kras vaccine primarily induced expansion of CD4+ effector T cells. VISTA antagonism by CA170 revealed strong efficacy against lung tumorigenesis with broad immunoregulatory functions that influence effector, memory and regulatory T cells, and drives an adaptive T cell tumor-specific immune response that enhances the efficacy of the KRAS vaccine.

VISTA: A Promising Target for Cancer Immunotherapy?

Agents targeting the B7 family co-inhibitory receptors cytotoxic T-lymphocyte antigen-4 (CTLA-4) and programmed cell death protein-1 (PD-1), or its ligand (PD-L1), have a pivotal role in clinical practice. V-domain Ig suppressor of T-cell activation (VISTA) is a protein highly conserved between species, with a similar amino acid sequence to the B7 family members, characterized by a particularly structural homology to PD-1. It has been counted as an emerging target within the list of novel targetable immune checkpoints in oncology. Physiologically, VISTA exerts a regulatory function on the immune system at several levels, particularly by modulating T cells activation. Its altered activity plays a role in many autoimmune diseases, and its expression has been found to be prognostically implicated in different cancer types in preclinical models. We hereby present the main evidence on the value of VISTA as an immune checkpoint in solid and hematological malignancies. We also review its value as a potential target for cancer immunotherapy, by reporting the results of Phase I and II clinical trials assessing the use of drugs targeting VISTA. The complexity of its pathway, along with some unclear biological aspects concerning its molecular interactions, currently represent a limit to the applicability of VISTA as an effective biomarker for immunotherapy in oncology. A deeper characterization of this immune checkpoint may help defining its value within immune signatures of solid and hematological malignancies, and to design future therapeutic strategies.

Immunotherapeutic Approaches in Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a rare and aggressive malignant disease affecting the mesothelium, commonly associated to asbestos exposure. The current therapeutic actions, based on cisplatin/pemetrexed treatment, are limited due to the late stage at which most patients are diagnosed and to the intrinsic chemo-resistance of the tumor. Another relevant point is the absence of approved therapies in the second line setting following progression of MPM after chemotherapy. Considering the poor prognosis of the disease and the fact that the incidence of this tumor is expected to increase in the next decade, novel therapeutic approaches are urgently needed. In the last few years, several studies have investigated the efficacy and safety of immune-checkpoint inhibitors (ICIs) in the treatment of unresectable advanced MPM, and a number of trials with immunotherapeutic agents are ongoing in both first line and second line settings. In this review, we describe the most promising emerging immunotherapy treatments for MPM (ICIs, engineered T cells to express chimeric antigen receptors (CARs), dendritic cells (DCs) vaccines), focusing on the biological and immunological features of this tumor as well as on the issues surrounding clinical trial design.

Immunotherapeutic strategies in pancreatic ductal adenocarcinoma (PDAC): current perspectives and future prospects

Pancreatic ductal adenocarcinoma (PDAC) is among the deadliest human malignancies with a dismal prognosis. During PDAC progression, the immune response is affected as cancer cells evade detection and elimination. Recently, there have been advances in the treatment of PDAC using immunotherapy, although a lot more work is yet to be done. In this review, we discuss these advances, challenges and potentials. We focus on existing and potential immune targets for PDAC, drugs used to target them, and some clinical trials conducted so far with them. Finally, novel targets in the tumour microenvironment such as stromal cells and other potential future areas to explore including bacterial therapy and the use of neoantigens in immunotherapy are highlighted.

Clinical and Recent Patents Applications of PD-1/PD-L1 Targeting Immunotherapy in Cancer Treatment-Current Progress, Strategy, and Future Perspective

Targeting PD-L1 and PD-1 interactions is a relatively new therapeutic strategy used to treat cancer. Inhibitors of PD-1/PD-L1 include peptides, small molecule chemical compounds, and antibodies. Several approved antibodies targeting PD-1 or PD-L1 have been patented with good curative effect in various cancer types in clinical practices. While the current antibody therapy is facing development bottleneck, some companies have tried to develop PD-L1 companion tests to select patients with better diagnosis potential. Meanwhile, many companies have recently synthesized small molecule inhibitors of PD-1/PD-L1 interactions and focused on searching for novel biomarker to predict the efficacy of anti-PD-1/PD-L1 drugs. This review summarized clinical studies and patent applications related to PD-1/PD-L1 targeted therapy and also discussed progress in inhibitors of PD-1/PD-L1.

Immune checkpoint inhibitors: Key trials and an emerging role in breast cancer

This review focuses on immune checkpoint inhibitors - immunomodulatory agents that aim to relieve tumour-mediated immune-cell suppression. Immune checkpoint proteins can be expressed on the tumour-cell or immune-cell populations. Immune checkpoint proteins dampen the immune response by inactivating immune cells capable of tumour destruction. Blockade of immune checkpoints has shown impressive results in a range of solid cancers, particularly melanoma and non-small cell lung cancer. The potential benefit of this class of drugs is widespread across most cancer types and an unprecedented number of clinical studies are underway to examine the benefit of these agents. The aims of this review are to: provide an overview of the key early immune checkpoint inhibitor trials involving drugs targeting programmed cell death-1 (PD-1), programmed cell death ligand-1 (PD-L1) and cytotoxic T-lymphocyte antigen-4 (CTLA-4) in multiple disease types; provide an overview of emerging therapies aimed at these targets; and provide a detailed exploration of the status of immune checkpoint inhibitors in breast cancer.

Discovery of New Immune Checkpoints: Family Grows Up

The first generation of immune checkpoint inhibitors (ICIs) including anti-CTLA-4 and anti-PD-1/anti-PD-L1 has achieved profound and great success. Till 2019 Q1, there are nine ICIs landing the oncology market: Ipilimumab (anti-CTLA-4, Bristol-Myers Squibb), Nivolumab (anti-PD-1, Bristol-Myers Squibb), Pembrolizumab (anti-PD-1, Merck), Atezolizumab (anti-PD-L1, Roche/Genentech), Durvalumab (anti-PD-L1, Astra Zeneca), Tremelimumab (anti-CTLA-4, Astra Zeneca), Cemiplimab (anti-PD-1, Sanofi/Regeneron), Toripalimab (anti-PD-1, Junshi), and Sintilimab (anti-PD-1, Innovent), which have covered the majority of hematologic and solid malignancies' indication. Beyond the considerable benefits for the patients, frustrated boundary still exists: limited response rate in monotherapy in late-stage population, poor effectiveness in neoplasms with immune desert and immune excluded types, and immune-related toxicities, some are life-threatened and with higher incidence in I-O combination regiment. Moreover, clinicians observed some cases switching to progression after achieving partial or complete response, indicating treatment failure or drug resistance. So people begin looking for the next generation of immune checkpoint members.

Comprehensive in vitro characterization of PD-L1 small molecule inhibitors

Blockade of the programmed cell death 1 (PD-1)/programmed cell death-ligand 1 (PD-L1) interaction has emerged as a powerful strategy in cancer immunotherapy. Recently, there have been enormous efforts to develop potent PD-1/PD-L1 inhibitors. In particular, Bristol-Myers Squibb (BMS) and Aurigene Discovery Technologies have individually disclosed several promising PD-1/PD-L1 inhibitors, whose detailed experimental data are not publicly disclosed. In this work, we report the rigorous and systematic in vitro characterization of a selected set of potent PD-1/PD-L1 macrocyclic peptide (BMSpep-57) and small-molecule inhibitors (BMS-103, BMS-142) from BMS and a peptidomimetic small-molecule inhibitor from Aurigene (Aurigene-1) using a series of biochemical and cell-based assays. Our results confirm that BMS-103 and BMS-142 are strongly active in biochemical assays; however, their acute cytotoxicity greatly compromised their immunological activity. On the other hand, Aurigene-1 did not show any activity in both biochemical and immunological assays. Furthermore, we also report the discovery of a small-molecule immune modulator, whose mode-of-action is not clear; however, it exhibits favorable drug-like properties and strong immunological activity. We hope that the results presented here will be useful in guiding the development of next-generation PD-1/PD-L1 small molecule inhibitors.