Frontiers in Immunology

Our medical research library holds 49 studies published in Frontiers in Immunology (2014–2026). Each entry links to the study's record on PubMed and, where there is one, to the publisher's page and a free full text. 48 have an abstract, the authors' own summary as PubMed records it: open "Abstract" to read it.

About the journal

• Publisher: Frontiers Research Foundation]
• Published: 2010 to the present, Switzerland
• Language: English
• ISSN: 1664-3224 (electronic)
• Its record in the NLM Catalog

2020s

• Case Report: Observational use of mycophenolate mofetil in probable steroid-unresponsive immune checkpoint inhibitor-associated transverse myelitis. L. Kong, X. Wang, T. Yu, et al. 2026;17:1933514. Case report PubMed · Publisher · Free full text

  Abstract

  Immune checkpoint inhibitor (ICI)-associated transverse myelitis (TM) is a rare and severe neurological immune-related adverse event (n-irAE) with an incidence of < 0.01%, and the clinical management of steroid-unresponsive cases remains extremely challenging. This article reports the case of a 37-year-old male patient with biphasic pleural mesothelioma who developed ICI-associated TM after treatment with nivolumab combined with ipilimumab. Initial treatment with high-dose glucocorticoids plus intravenous immunoglobulin (IVIg) was ineffective. After mycophenolate mofetil (MMF) was added in combination with steroids for 1 month, the patient's neurological function showed slight improvement, and intramedullary contrast-enhanced signals on spinal MRI showed partial reduction. However, spinal cord cystic or myelomalacic changes suggested potentially irreversible parenchymal injury. Currently, the patient has restarted pemetrexed combined with carboplatin chemotherapy, and the disease status is stable. Based on recently published case series, case reports, and systematic reviews, this article discusses the second-line treatment strategies for steroid-unresponsive ICI-associated TM, aiming to provide a reference for clinical practice in managing such rare cases.

  Copyright © 2026 Kong, Wang, Yu, Wang, Yang, Zhang and Zhong.

• Evaluating mesothelin as an immunotherapeutic target for endogenous T cells. K. Koukoulias, R. Yanagisawa, A.G. Torres Chavez, et al. 2026;17:1853409. PubMed · Publisher · Free full text

  Abstract

  Background: Mesothelin (MSLN) is a GPI-anchored cell surface glycoprotein that is overexpressed in various solid tumors, including mesothelioma, triple-negative breast cancer, colon, ovarian and pancreatic cancer, with restricted normal tissue expression.

  Methods: To explore the immunogenicity and immunotherapeutic potential of MSLN to T cells with native receptor specificity, 29 individuals of diverse HLA backgrounds were interrogated for T cell activity against MSLN.

  Results: Twenty one (72%) subjects (21/29) mounted a specific T cell response when repetitively challenged with MSLN antigen. Reactive cells were Th1-polarized, polyfunctional, predominantly detected in the CD8+ T cell compartment and cytotoxic toward autologous and MSLN+/HLA-matched tumor cell lines in conventional 2D in vitro assays. Furthermore, these cells produced anti-tumor effects in a novel 3D tumor spheroid model system established to evaluate the potency of reactive cells against tumors including pancreatic, cervical, and colorectal cancer and mesothelioma.

  Conclusions: These preclinical findings lay the groundwork for further exploration of MSLN as a potential immunotherapeutic target for T cells via the native T cell receptor.

  Copyright © 2026 Koukoulias, Yanagisawa, Torres Chavez, Papayanni, Velazquez, Lee, Vasileiou and Leen.

• GlycoRNA-related cellular program scoring identifies Siglec- and myeloid-associated tumor microenvironments for glycoRNA validation. M. Kong, X. Guan, Y. Jing, et al. 2026;17:1928501. PubMed · Publisher · Free full text

  Abstract

  Background: Glycosylated RNAs (glycoRNAs) represent a recently recognized connection between RNA biology and cell-surface glycobiology. However, whether glycoRNA-related processes are relevant to human tumors remains unclear, partly because direct glycoRNA measurements are not yet available across large cancer cohorts. We therefore used transcriptomic data to identify tumor settings in which glycoRNA-related programs may be most suitable for further experimental validation.

  Methods: We curated a glycoRNA-focused literature evidence base and manually reviewed the top extracted relations to define gene modules related to RNA identity, N-glycan and sialylation pathways, RNA trafficking, and lectin/Siglec recognition. The glycoRNA-related cellular program score is an expression-based composite score representing coordinated glycoRNA-related cellular programs, including RNA processing, glycan biosynthesis, trafficking, and lectin/Siglec recognition. It is designed to prioritize tumor contexts for experimental glycoRNA validation. The score was applied to 9,186 TCGA tumors from 32 cancer types and analyzed together with clinical variables, leukocyte fraction, immune signatures, Siglec/checkpoint/myeloid-axis scores, and non-overlapping sensitivity models. Glioblastoma single-cell and spatial transcriptomic datasets were used for additional context-level validation.

  Results: Higher glycoRNA-related cellular program scores were observed in several tumor types, including stomach adenocarcinoma, glioblastoma, lung adenocarcinoma, esophageal carcinoma, mesothelioma, pancreatic adenocarcinoma, breast cancer, and lung squamous carcinoma. Survival analyses did not show robust FDR-significant associations after adjustment for age, sex, stage, and tumor type, suggesting that the score should not be interpreted as a general prognostic biomarker. In sensitivity analyses that removed immune and Siglec-related genes from the predictor, the score remained associated with Siglec-decoder, myeloid, checkpoint, and integrated niche features after adjustment for leukocyte fraction and cancer-type effects. Within-cancer meta-analysis supported these associations across cancer types, although effect sizes varied. In glioblastoma, higher scores were found in tumor, myeloid, mesenchymal, and niche-associated compartments in single-cell and spatial analyses.

  Conclusions: This study presents an expression-based map of glycoRNA-related cellular program across human cancers. The results suggest that glycoRNA-related transcriptional programs tend to occur in immune- and myeloid-enriched tumor microenvironments, particularly those involving Siglec-associated features. These findings prioritize tumor contexts for biochemical, imaging, spatial, and perturbation-based glycoRNA validation.

  Copyright © 2026 Kong, Guan, Jing, Xie, Zhao, Huang, Yu and Zhang.

• Reprogramming the tumor microenvironment in mesothelioma: from immune suppression to therapeutic opportunity. L. Cerbone, A. Garau, A. Balossino, et al. 2026;17:1814514. Review PubMed · Publisher · Free full text

  Abstract

  Pleural mesothelioma (PM) is a rare and aggressive cancer with limited treatment options and poor prognosis. Unlike other thoracic cancers responding well to immunotherapy, PM typically lacks key predictive biomarkers such as Programmed Death-Ligand 1 (PD-L1) tumor expression. Nonetheless, immune checkpoint inhibitors (ICIs) have shown clinical activity in PM, particularly in non-epithelioid subtypes. However, only a subset of patients benefits from this approach, and resistance remains a major challenge. A growing body of evidence suggests that tumor microenvironment (TME) plays a central role in shaping this resistance. In PM, the TME is notably immunosuppressive, dominated by regulatory T cells, myeloid-derived suppressor cells, and tumor-associated macrophages. These elements act as a shield against immune activation, limiting the efficacy of ICIs. Novel therapeutic strategies aimed at depleting or modulating suppressive immune populations within the TME are emerging as promising avenues to overcome resistance and enhance the effectiveness of ICIs. In this narrative review, we examine the unique features of the TME in PM, its role in immunotherapy resistance, and emerging strategies aimed at harnessing or remodeling the TME to improve patient outcomes.

  Copyright © 2026 Cerbone, Garau, Balossino, Martinotti, Ranzato, Genova, Rigo, Meda, Ravera, Parra, Piccirillo, Gurrera, Terminella, Manitto, Croce, Coco and Grosso.

• Tumor treating fields in malignant pleural mesothelioma: from cytoskeletal collapse to immunophenotypic conversion. X. Ma, Z. Zuo, Y. Sun, et al. 2026;17:1782708. Review PubMed · Publisher · Free full text

  Abstract

  The therapeutic efficacy in malignant pleural mesothelioma (MPM) is severely hindered by its dense stromal barrier and immunosuppressive microenvironment. Although Tumor Treating Fields (TTFields) have demonstrated significant survival benefits in clinical trials, their underlying mechanisms extend well beyond simple mitotic arrest. This review delineates a "multidimensional biophysical remodeling" atlas of TTFields in MPM. First, we highlight that TTFields physically disrupt actin-dependent intercellular "tunneling nanotubes, " thereby severing the tumor's communication and metabolic rescue networks. Second, physical stress downregulates the Fanconi Anemia-BRCA pathway, inducing a state of "conditional BRCAness" that specifically sensitizes tumors to DNA-damaging agents. Finally, this cascade triggers immunogenic cell death and orchestrates a chemokine storm, which is hypothesized to facilitate the conversion of the tumor microenvironment from an immune "cold" to a "hot" phenotype. Collectively, by integrating the physical disintegration of subcellular structures with immunological remodeling, TTFields may offer a hypothetical theoretical framework for overcoming therapeutic resistance in MPM.

  Copyright © 2026 Ma, Zuo, Sun and An.

• Case report: Diagnosis of impaired consciousness in a cancer patient using immune checkpoint inhibitors. D. Cathalifaud, C. Basáez, T. Yáñez. 2025;16:1458686. Case report PubMed · Publisher · Free full text

  Abstract

  Immune checkpoint inhibitors (ICIs) are drugs that are being increasingly used in the field of oncology; due to their mechanism of action, they can present immune-related adverse effects (IRAEs), with various clinical manifestations, one of which is delirium. We present the case of a patient diagnosed with pleural mesothelioma that started combined palliative immunotherapy two months before admission. She was hospitalized for delirium with psychotic symptoms and a comprehensive neurological and etiological examination for this pathology was performed, revealing undetectable TSH levels, indicating the etiology of the condition as thyrotoxicosis in the context of autoimmune thyroiditis, secondary to treatment with ICIs. Symptomatic treatment with beta-blockers was initiated, leading to progressive improvement. This case brings awareness of impaired consciousness and neuropsychiatric symptoms as manifestation of IRAEs and the difficulty of their diagnosis: there may also be several other causes of impaired consciousness, so the characterization of delirium requires a multifaceted approach to determine the underlying cause, taking into account direct cancer-related complications and those stemming from the treatments received by this group of patients. Endocrinological immune-related adverse events (IRAEs), such as thyroid IRAEs, generally have a low lethality rate, do not necessarily require discontinuation of therapy, and are linked to a more favorable oncological prognosis. Conversely, neurological IRAEs, though rare, constitute a contraindication for further use of ICIs. This clinical case emphasizes the importance of the systematic study of consciousness impairment in cancer patients, and of considering multiple IRAEs that could lead to changes in oncological therapy when establishing possible etiologies.

  Copyright © 2025 Cathalifaud, Basáez and Yáñez.

• Combination of PD-1/PD-L1 and CTLA-4 inhibitors in the treatment of cancer - a brief update. J. Park, B.S. Skålhegg. 2025;16:1680838. Review PubMed · Publisher · Free full text

  Abstract

  The introduction of immune checkpoint inhibitors (ICIs) has revolutionized cancer therapy, offering durable responses in multiple malignancies by targeting regulatory pathways such as programmed cell death protein 1 (PD-1), its ligand (PD-L1), and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4). These pathways, which normally maintain immune tolerance and homeostasis, can be exploited by tumors to evade immune surveillance. Dual blockade using monoclonal antibodies (mAbs) targeting PD-1/PD-L1 and CTLA-4 has shown synergistic effects, improving response rates, overall survival, and progression-free survival in several cancer types. The U.S. Food and Drug Administration (FDA) has approved two such combinations: nivolumab plus ipilimumab and durvalumab plus tremelimumab, based on demonstrated clinical benefit in melanoma, renal cell carcinoma, colorectal cancer, hepatocellular carcinoma, non-small cell lung cancer, pleural mesothelioma, and esophageal squamous cell carcinoma. However, clinical benefit has not been consistent across all tumor types, with limited efficacy observed in cancers such as glioblastoma, head and neck squamous cell carcinoma, and Merkel cell carcinoma. Additionally, combination therapy is associated with a higher incidence of immune-related adverse events, affecting multiple organ systems and necessitating careful dosing strategies to balance efficacy and toxicity. This review summarizes the current landscape of FDA-approved PD-1/PD-L1 and CTLA-4 combinations, their therapeutic achievements, clinical limitations, and supports future research in combination immunotherapy.

  Copyright © 2025 Park and Skålhegg.

• Efficacy and safety of PD-1/PD-L1 and CTLA-4 immune checkpoint inhibitors in the treatment of diffuse pleural mesothelioma: a systematic review and meta-analysis. P. Sun, D. Song, N. Ma, et al. 2025;16:1578746. Systematic review · Meta-analysis PubMed · Publisher · Free full text

  Abstract

  Background: While clinical trials confirm the therapeutic value of PD-1/PD-L1 and CTLA-4 inhibitors in diffuse pleural mesothelioma, their real-world safety and efficacy profiles remain incompletely defined. This meta-analysis synthesizes clinical evidence to comprehensively evaluate these outcomes, addressing an urgent need for robust real-world evidence.

  Methods: PubMed, Embase, the Cochrane Library were systematically searched for relevant studies. Outcomes including median progression-free survival (mPFS), median overall survival (mOS), 1-year overall survival (1-y OS), 1 year progression-free survival (1-year PFS),objective response rate (ORR), disease control rate (DCR), complete response(CR),partial response (PR), stable disease(SD), progressive disease(PD), treatment-related adverse events (TRAEs) and ≥grade 3 TRAEs were extracted for further analysis. The risk of bias was assessed by subgroup analysis.

  Results: 14 articles with 1345 patients were identified and subjected to meta-analysis. With regard to survival analysis, the pooled mOS and mPFS were 6.66 months (95%CI 4.85-9.16) and 2.92 months (95%CI 2.23-3.83), respectively. In terms of tumor response, the pooled ORR and DCR were 21% (95%CI 6%-41%) and 49% (95%CI 27%-71%), respectively. The pooled AEs rate and ≥ grade 3 AEs rate were 94% (95%CI 86%-99%) and 44% (95%CI 30%-58%).

  Conclusion: PD-1/PD-L1 inhibitors combined with CTLA-4 inhibitors have shown effective clinical responses in the treatment of Diffuse Pleural Mesothelioma (DPM). Although the incidence of adverse reactions is high, they are generally tolerable.

  Systematic Review Registration: www.inplasy.com, identifier INPLASY202520045.

  Copyright © 2025 Sun, Song, Ma, Hou, Liu, Gao and Tian.

• Elucidating the immunomodulatory roles and mechanisms of CUL4B in the immune system: a comprehensive review. S. He, Z. Wang, Y. Zhu, et al. 2025;16:1473817. Review PubMed · Publisher · Free full text

  Abstract

  Cullin 4B (CUL4B), a pivotal member of the Cullins protein family, plays a crucial role in immune regulation and has garnered significant research attention. CUL4B, through the Cullin 4B-RING E3 ubiquitin ligase (CRL4B) complex, regulates CD4+ T cell differentiation, fostering a balance between TH1 and TH2 subsets, and expedites DNA damage repair to bolster T cell persistence. In B cells, CUL4B upregulation stimulates immune responses but is linked to an unfavorable prognosis in lymphoma. In innate immunity, CUL4B modulates Toll-like receptor (TLR)-mediated anti-inflammatory responses, enhancing macrophage migration and adhesion. CUL4B also plays a role in potentiating anti-tumor immunity by restricting the activity of myeloid-derived suppressor cells (MDSCs). In disease pathogenesis, CUL4B limits MDSCs to enhance anti-tumor effects, and its inhibition in experimental autoimmune encephalomyelitis (EAE) models have demonstrated beneficial effects, underscoring its potential therapeutic significance in autoimmune diseases. Furthermore, CUL4B is involved in various immune-related cancers and inflammation, including pleural mesothelioma, human osteosarcoma, and colitis-associated cancer. In metabolic diseases, CUL4B regulates adipose tissue and insulin sensitivity, with its depletion improving metabolic phenotypes. This review highlights the pivotal role of CUL4B in maintaining immune homeostasis and provides novel perspectives and insights into the understanding and development of treatments for immune-related disorders.

  Copyright © 2025 He, Wang, Zhu, Sun and Lin.

• Expression patterns of estrogen and androgen receptors in NSCLC patients according to the PD-L1 profile. V. Rodriguez-Lara, G. Cortés-Ramírez, I.A. Angeles-Torres, et al. 2025;16:1602579. PubMed · Publisher · Free full text

  Abstract

  Background: Lung cancer is the leading cause of cancer-related death worldwide, with non-small cell lung cancer (NSCLC) being the most common type. Immunotherapy targeting programmed death ligand-1 (PD-L1) blockade has significantly improved survival, but differences in responses by sex have been reported, suggesting a possible role of sex hormones. Estrogens and androgens, through their receptors support lung carcinogenesis, but their role in immune evasion via the PD-1/PD-L1 pathway remains poorly understood.

  Materials And Methods: We analyzed by immunohistochemistry the expression patterns of estrogen receptors (ERα and ERβ) and androgen receptor (AR) in 95 PD-L1-positive (PD-L1+) and 72 PD-L1 negative (PD-L1-) NSCLC patients by sex and hormonal status. We also investigated associations between hormonal receptors, PD-L1 profile, PD-L1 tumor proportion score (TPS), and clinical features (cancer stage according to the TNM stage of cancer, smoking history, wood smoke exposure, and asbestos exposure).

  Results: ERβ was the predominant form of estrogen receptor in PD-L1- patients, while ERα expression was significantly higher in PD-L1+ patients and strongly associated with the PD-L1+ profile, regardless of sex or hormonal status. AR expression was low across all groups and showed no association with PD-L1. Among PD-L1+ patients, ERα expression levels were highest in premenopausal women, followed by men and postmenopausal women. ERα levels in the PD-L1+ group, were not associated with PD-L1 TPS or with clinical features.

  Conclusion: The estrogen pathway, particularly via ERα, plays a key role in PD-L1 expression and may contribute to tumor immune evasion. Antiestrogen therapy could represent a promising strategy to enhance immunotherapy efficacy in patients expressing ERs.

  Copyright © 2025 Rodriguez-Lara, Cortés-Ramírez, Angeles-Torres, Rodriguez-Cid, Pedraza-Reyes, Avila-Costa, Ordoñez-Librado and Cerbón.

• Improvement in the function of self-activating chimeric antigen receptor by replacing the linker sequence. T. Kouro, D. Hoshino, Y. Mano, et al. 2025;16:1502607. PubMed · Publisher · Free full text

  Abstract

  Chimeric antigen receptor (CAR)-T cell therapy is an effective treatment for hematological cancers; however, challenges remain in its application to solid tumors. Among these, the control of CAR-T cell exhaustion is important. The relationship between tonic signals generated by the CAR self-activation and CAR-T cell exhaustion has attracted considerable attention. The magnitude of the tonic signal is known to depend on the structure of the extracellular portion of CAR, but the role of the linker sequence of the single-chain variable region (scFv) in the tonic signal and function in CAR-T cells has not been clarified. In this study, we compared two scFv linkers, G4S and Whitlow/218, in self-activating SKM-CAR, which recognized a malignant mesothelioma-specific modified HEG1 molecule. We observed no differences in cell surface phenotypes, NFAT and NFκB signaling intensities, and gene expression profiles between SKM-CAR T cells with these different linkers. However, switching from the G4S to the Whitlow/218 linker in SKM-CAR-T cells with the CD28 co-stimulatory domain significantly altered cytokine expression after antigen stimulation and improved the in vitro tumor cell killing activity, but not the in vivo tumor control. This is the first study describing the advantages of the Whitlow/218 linker over the G4S linker for some aspects of CAR-T cell function.

  Copyright © 2025 Kouro, Hoshino, Mano, Tsuji, Himuro, Imai and Sasada.

• Pan-cancer analysis of TMED2: unraveling potential immune characteristics and prognostic value in cancer therapy. Z. Wang, C. Sun, P. Wang, et al. 2025;16:1578627. PubMed · Publisher · Free full text

  Abstract

  Background: Transmembrane emp24 domain-containing protein 2 (TMED2) is involved in the sorting and transport of proteins between the Golgi apparatus and the endoplasmic reticulum. Recent research has identified a close association between TMED2 and tumorigenesis, yet its regulatory role and underlying mechanisms in pan-cancer signaling pathways remain unexplored.

  Methods: We conducted a comprehensive pan-cancer analysis of TMED2 using multiple public databases. These analyses included assessments of prognostic significance, gene mutations, pathway enrichment, single-cell sequencing analysis, immune characteristics, co-expressed gene PPI network analysis, as well as the therapeutic response of TMED2 in immunotherapy and small molecule sensitivity. Finally, we examined the role that TMED2 plays at the cellular level.

  Results: Our results show that the mRNA levels of TMED2 differ significantly between cancerous and normal tissues and are closely associated with cancer prognosis. Specifically, in CESC, MESO, LGG, and UVM, overexpression of TMED2 correlates with patient prognosis and various clinical pathological features. TMED2 is significantly associated with immune infiltration (including endothelial cells, neutrophils, dendritic cells, and eosinophils), immune checkpoints (CD274, HAVCR2, PDCD1LG2, and SIGLEC15), and signaling pathways (cell cycle and PI3K/Akt). Single-cell sequencing reveals that TMED2 is predominantly expressed in tumor cells of cervical cancer, glioma, and mesothelioma. Enrichment analysis shows that genes co-expressed with TMED2 are primarily involved in processes like endoplasmic reticulum stress and the ERAD pathway. Furthermore, cellular studies indicated that TMED2 expression promotes the growth, migration and invasion of glioma cells.

  Conclusion: Our integrated analysis suggests that targeting TMED2, along with its associated genes and signaling pathways, could represent a new strategy for cancer immune treatment.

  Copyright © 2025 Wang, Sun, Wang, Lin, Wu and Gu.

• Radical hemithorax radiotherapy induces an increase in circulating PD-1+ T lymphocytes and in the soluble levels of PD-L1 in malignant pleural mesothelioma patients: a possible synergy with PD-1/PD-L1 targeting treatment?. A. Revelant, F. Gessoni, M. Montico, et al. 2025;16:1534766. PubMed · Publisher · Free full text

  Abstract

  Malignant Pleural Mesothelioma (MPM) is an aggressive tumor associated with asbestos exposure, characterized by a poor prognosis, managed with surgery, chemotherapy and radiotherapy. Recently, immunotherapy gives a survival advantage compared to chemotherapy, but limited to the non-epithelioid histotype, the rarest type. Radical hemithorax radiotherapy (RHRT) improves the Overall Survival (OS) of MPM patients, irrespective of histotype, and is able to induce immunomodulatory effects. In this study we aim to investigate changes in circulating T lymphocytes phenotype and activity, in MPM patients undergoing RHRT, to evaluate a possible therapeutic space for immunotherapy in this setting. To assess immunomodulatory effects of RHRT we evaluate peripheral blood samples of 35 MPM patients collected before treatment, at the end of RT, and 1 month later. We first notice that higher Lymphocyte-to-Monocyte Ratio (LMR) levels, before RT, are associated with an improved OS. The immune monitoring performed by ELISA assays reveals a significant increase in the serum levels of soluble PD-L1 (sPD-L1) and IFN-γ at the end of RHRT. Furthermore, the percentage of PD-1+ cells, evaluated by flow cytometry, significantly raise after RHRT in T cells, both CD4+ and CD8+. Also the proportion of proliferative cells is significantly expanded after RHRT in all T cell subtypes. After treatment we observe a significant increase in the number of patients showing WT-1 specific CD4+ T cells, measured by intracellular staining. The TCR repertoire analysis, investigated by Next Generation Sequencing, reveals an increased number of expanded T-cell clones after RHRT, and an association between TCR clonality and the percentage of proliferating cytotoxic T lymphocytes. The comparison of TCR sequences obtained in our cohort with those described in a literature cohort of MPM patients, reveals common entries, specific for MPM-associated antigens including WT-1. In this setting, pre-treatment levels of LMR seem to have a positive prognostic role, and RHRT would appear to induce immunomodulating effects, potential biomarkers for immunotherapy eligibility: i.e. increased PD-1+ T lymphocytes, proliferating T cells, expanded T cell clones and augmented levels of sPD-L1. These data suggest the design of a prospective study evaluating a maintenance immunotherapy after RHRT in MPM, even in the epithelioid histotype.

  Copyright © 2025 Revelant, Gessoni, Montico, Dhibi, Brisotto, Casarotto, Zanchetta, Paduano, Sperti, Evangelista, Giordari, De Re, Trovò, Minatel, Mascarin, Steffan and Muraro.

• Antisense targeting of FOXP3+ Tregs to boost anti-tumor immunity. T. Akimova, L. Wang, Z. Bartosh, et al. 2024;15:1426657. PubMed · Publisher · Free full text

  Abstract

  Our goal is to improve the outcomes of cancer immunotherapy by targeting FOXP3+ T-regulatory (Treg) cells with a next generation of antisense oligonucleotides (ASO), termed FOXP3 AUMsilence ASO. We performed in vitro experiments with human healthy donor PBMC and clinical samples from patients with lung cancer, mesothelioma and melanoma, and tested our approach in vivo using ASO FOXP3 in syngeneic murine cancer models and in humanized mice. ASO FOXP3 had no effects on cell viability or cell division, did not affect expression of other FOXP members, but decreased expression of FOXP3 mRNA in PBMC by 54.9% and in cancer samples by 64.7%, with corresponding 41.0% (PBMC) and 60.0% (cancer) decreases of Treg numbers (all p<0.0001). Hence, intratumoral Treg were more sensitive to the effects of ASO FOXP3 than peripheral blood Tregs. Isolated human Treg, incubated with ASO FOXP3 for 3.5 hours, had significantly impaired suppressive function (66.4%) versus Scramble control. In murine studies, we observed a significant inhibition of tumor growth, while 13.6% (MC38) to 22% (TC1) of tumors were completely resorbed, in conjunction with ~50% decrease of Foxp3 mRNA by qPCR and decreased numbers of intratumoral Tregs. In addition, there were no changes in FOXP3 mRNA expression or in the numbers of Tregs in draining lymph nodes and in spleens of tumor bearing mice, confirming that intratumoral Treg had enhanced sensitivity to ASO FOXP3 in vivo compared to other Treg populations. ASO FOXP3 Treg targeting in vivo and in vitro was accompanied by significant downregulation of multiple exhaustion markers, and by increased expression of perforin and granzyme-B by intratumoral T cells. To conclude, we report that targeting the key Treg transcription factor FOXP3, with ASO FOXP3, has a powerful anti-tumoral effect and enhances T cell response in vitro and in vivo.

  Copyright © 2024 Akimova, Wang, Bartosh, Christensen, Eruslanov, Singhal, Aishwarya and Hancock.

• Serum cytokines as a biomarker for immune checkpoint inhibitor toxicity in patients with pleural mesothelioma. S.J. Farooqi, Z. Zhao, Å.K. Öjlert, et al. 2024;15:1480183. PubMed · Publisher · Free full text

  Abstract

  Background: Pleural mesothelioma (PM) is a rare cancer with a dismal prognosis. Dual immune checkpoint inhibitors have improved overall survival, but the rate of immune-related adverse events (irAEs) is high. Serum cytokines reflect systemic immune reactions and may serve as biomarkers for irAEs.

  Patients And Methods: Patients with pleural mesothelioma treated with nivolumab and ipilimumab with or without UV1 vaccine in the NIPU study were included. Serum cytokine levels were measured by Bio-Plex Pro Human Cytokine Screening 48-Plex Panel Assay. Correlations between cytokine levels and irAEs were analyzed by generalized linear mixed models to identify potential diagnostic and predictive biomarkers.

  Results: Higher levels of MIG, eotaxin, MIP-1α, IP-10, TNF-α, MIP-1β, IL-4, MIF, IL-16, IL-2RA, SCGF.β and PDFG-BB at baseline are associated with increased risk of developing one or more irAEs. In particular, higher baseline levels of MIG are positively associated with thyroiditis and hypophysitis, and elevated levels of IP-10 and MIG to dermatitis. During the course of treatment, higher levels of MIG, eotaxin, MIF, TNF-α, MIP-1β, IL-4 and IL-16 are associated with an ongoing irAE. We found both predictive and diagnostic value of MIF with fatigue and of eotaxin with both colitis and pneumonitis. Higher levels of CTACK is associated with a lower risk of developing hepatitis, both before and after treatment.

  Conclusions: Elevated levels of certain cytokines, both before and after onset of treatment, correlate with specific irAEs in PM patients receiving ICIs. These cytokines may be used as biomarkers to predict and detect irAES.

  Copyright © 2024 Farooqi, Zhao, Öjlert, Thunold, Juul, Bjaanæs, Horndalsveen, Nymoen, Helland and Haakensen.

• Spatially-resolved analyses of muscle invasive bladder cancer microenvironment unveil a distinct fibroblast cluster associated with prognosis. C. Feng, Y. Wang, W. Song, et al. 2024;15:1522582. PubMed · Publisher · Free full text

  Abstract

  Background: Muscle-invasive bladder cancer (MIBC) is a prevalent cancer characterized by molecular and clinical heterogeneity. Assessing the spatial heterogeneity of the MIBC microenvironment is crucial to understand its clinical significance.

  Methods: In this study, we used imaging mass cytometry (IMC) to assess the spatial heterogeneity of MIBC microenvironment across 185 regions of interest in 40 tissue samples. We focused on three primary parameters: tumor (T), leading-edge (L), and nontumor (N). Cell gating was performed using the Cytobank platform. We calculated the Euclidean distances between cells to determine cellular interactions and performed single-cell RNA sequencing (scRNA-seq) to explore the molecular characteristics and mechanisms underlying specific fibroblast (FB) clusters. scRNA-seq combined with spatial transcriptomics (ST) facilitated the identification of ligand-receptor (L-R) pairs that mediate interactions between specific FB clusters and endothelial cells. Machine learning algorithms were used to construct a prognostic gene signature.

  Results: The microenvironments in the N, L, and T regions of MIBC exhibited spatial heterogeneity and regional diversity in their components. A distinct FB cluster located in the L region-identified as S3-is strongly associated with poor prognosis. IMC analyses demonstrated a close spatial association between S3 and endothelial cells, with S3-positive tumors exhibiting increased blood vessel density and altered vascular morphology. The expression of vascular endothelial growth factor receptor and active vascular sprouting were significant in S3-positive tumors. scRNA-seq and ST analyses indicated that the genes upregulated in S3 were associated with angiogenesis. NOTCH1-JAG2 signaling pathway was identified as a significant L-R pair specific to S3 and endothelial cell interactions. Further analysis indicated that YAP1 was a potential regulator of S3. Machine learning algorithms and Gene Set Variation Analysis were used to establish an S3-related gene signature that was associated with the poor prognosis of tumors including MIBC, mesothelioma, glioblastoma multiforme, lower-grade glioma, stomach adenocarcinoma, uveal melanoma, kidney renal clear cell carcinoma, kidney renal papillary cell carcinoma, and lung squamous cell carcinoma.

  Conclusions: We assessed the spatial landscape of the MIBC microenvironment and revealed a specific FB cluster with prognostic potential. These findings offer novel insights into the spatial heterogeneity of the MIBC microenvironment and highlight its clinical significance.

  Copyright © 2024 Feng, Wang, Song, Liu, Mo, Liu, Wu, Qin, Wang, Tao, He, Tang, Xie, Wang and Li.

• Anti-PD1 does not improve pyroptosis induced by γδ T cells but promotes tumor regression in a pleural mesothelioma mouse model. K.S. Lui, Z. Ye, H.C. Chan, et al. 2023;14:1282710. PubMed · Publisher · Free full text

  Abstract

  Introduction: Mesothelioma is an aggressive tumor in the pleural cavity that is difficult to treat. Diagnosis is usually late with minimal treatment options available for the patients and with unfavorable outcomes. However, recent advances in immunotherapy using γδ T cells may have potential against mesothelioma, given its ample tumoricidal and tumor-migratory properties could allow its infiltration to the widespread tumor mass. Thus, we hypothesize that Vδ2 T cells can perform cytotoxic activities against mesothelioma especially when combined with immune checkpoint blocker against PD-1.

  Methods: Human Vδ2 T cells were expanded from peripheral blood mononuclear cells using Tetrakis-pivaloyloxymethyl 2-(thiazole-2-ylamino) ethylidene-1,1-bisphosphonate (PTA) plus IL-2 for 13 days, before used to test for cytotoxicity against mesothelioma cell lines. Mesothelioma-bearing mice was established by Intrapleural administration of mesothelioma cell lines to test for the efficacy of Vδ2 T cells plus anti-PD-1 antibody combination treatment. Pyroptosis was evaluated by cell morphology, western blot analysis, and ELISA experiments. Flow cytometry was used to examine expression of BTN2A1, BTN3A1, PD-L1, PD-L2 on mesothelioma cell lines. Immunofluorescence staining was performed to detect Vδ2 T cells post adoptive transfer and characteristics of pyroptosis in ex vivo mesothelioma tissue sections.

  Results: Indeed, our data demonstrated that Vδ2 T cells killing mesothelioma can be enhanced by anti-PD-1 antibody in vitro, especially for high PD-1 expressing cells, and in vivo in the intrapleural mesothelioma mice model established by us. Adoptive transfer of Vδ2 T cells into these mice leads to tumor regression by 30-40% compared to control. Immunofluorescence of the tumor section confirmed infiltration of Vδ2 T cells into the tumor, especially to cells with BTN2A1 expression (a Vδ2 T cell activating molecule) despite PD-L1 co-localization. Interestingly, these cells co-expressed cleaved gasdermin D, suggesting that pyroptosis was induced by Vδ2 T cells. This was verified by Vδ2 T/mesothelioma co-culture experiments demonstrating membrane ballooning morphology, increased cleaved caspase-3 and gasdermin E, and upregulated IL-1β and IL-18.

  Discussion: Vδ2 T cells plus anti-PD1 exhibited cytotoxicity against mesothelioma in vivo. However, we found no advantage for anti-PD-1 against PD-1 high expressing Vδ2 T cells in promoting pyroptosis. Taken together, our work demonstrated that Vδ2 T cells combined with anti-PD-1 antibody can be developed as a potential combination immunotherapy for mesothelioma.

  Copyright © 2023 Lui, Ye, Chan, Tanaka and Cheung.

• ChemR23 activation reprograms macrophages toward a less inflammatory phenotype and dampens carcinoma progression. M. Lavy, V. Gauttier, A. Dumont, et al. 2023;14:1196731. PubMed · Publisher · Free full text

  Abstract

  Introduction: Tumor Associated Macrophages (TAM) are a major component of the tumor environment and their accumulation often correlates with poor prognosis by contributing to local inflammation, inhibition of anti-tumor immune response and resistance to anticancer treatments. In this study, we thus investigated the anti-cancer therapeutic interest to target ChemR23, a receptor of the resolution of inflammation expressed by macrophages, using an agonist monoclonal antibody, αChemR23.

  Methods: Human GM-CSF, M-CSF and Tumor Associated Macrophage (TAM)-like macrophages were obtained by incubation of monocytes from healthy donors with GM-CSF, M-CSF or tumor cell supernatants (Breast cancer (BC) or malignant pleural mesothelioma (MPM) cells). The effects of αChemR23 on macrophages were studied at the transcriptomic, protein and functional level. Datasets from The Cancer Genome Atlas (TCGA) were used to study CMKLR1 expression, coding for ChemR23, in BC and MPM tumors. In vivo, αChemR23 was evaluated on overall survival, metastasis development and transcriptomic modification of the metastatic niche using a model of resected triple negative breast cancer.

  Results: We show that ChemR23 is expressed at higher levels in M-CSF and tumor cell supernatant differentiated macrophages (TAM-like) than in GM-CSF-differentiated macrophages. ChemR23 activation triggered by αChemR23 deeply modulates M-CSF and TAM-like macrophages including profile of cell surface markers, cytokine secretion, gene mRNA expression and immune functions. The expression of ChemR23 coding gene (CMKLR1) strongly correlates to TAM markers in human BC tumors and MPM and its histological detection in these tumors mainly corresponds to TAM expression. In vivo, treatment with αChemR23 agonist increased mouse survival and decreased metastasis occurrence in a model of triple-negative BC in correlation with modulation of TAM phenotype in the metastatic niche.

  Conclusion: These results open an attractive opportunity to target TAM and the resolution of inflammation pathways through ChemR23 to circumvent TAM pro-tumoral effects.

  Copyright © 2023 Lavy, Gauttier, Dumont, Chocteau, Deshayes, Fresquet, Dehame, Girault, Trilleaud, Neyton, Mary, Juin, Poirier, Barillé-Nion and Blanquart.

• Complement protein C1q stimulates hyaluronic acid degradation via gC1qR/HABP1/p32 in malignant pleural mesothelioma. A. Balduit, R. Vidergar, P. Zacchi, et al. 2023;14:1151194. PubMed · Publisher · Free full text

  Abstract

  Complement component C1q can act as a pro-tumorigenic factor in the tumor microenvironment (TME). The TME in malignant pleural mesothelioma (MPM) is rich in C1q and hyaluronic acid (HA), whose interaction enhances adhesion, migration and proliferation of malignant cells. HA-bound C1q is also capable of modulating HA synthesis. Thus, we investigated whether HA-C1q interaction would affect HA degradation, analyzing the main degradation enzymes, hyaluronidase (HYAL)1 and HYAL2, and a C1q receptor candidate. We first proceeded with the characterization of HYALs in MPM cells, especially HYAL2, since bioinformatics survival analysis revealed that higher HYAL2 mRNA levels have an unfavorable prognostic index in MPM patients. Interestingly, Real-Time quantitative PCR, flow cytometry and Western blot highlighted an upregulation of HYAL2 after seeding of primary MPM cells onto HA-bound C1q. In an attempt to unveil the receptors potentially involved in HA-C1q signaling, a striking co-localization between HYAL2 and globular C1q receptor/HABP1/p32 (gC1qR) was found by immunofluorescence, surface biotinylation and proximity ligation assays. RNA interference experiments revealed a potentially regulatory function exerted by gC1qR on HYAL2 expression, since C1QBP (gene for gC1qR) silencing unexpectedly caused HYAL2 downregulation. In addition, the functional blockage of gC1qR by a specific antibody hindered HA-C1q signaling and prevented HYAL2 upregulation. Thus, C1q-HA interplay is responsible for enhanced HYAL2 expression, suggesting an increased rate of HA catabolism and the release of pro-inflammatory and pro-tumorigenic HA fragments in the MPM TME. Our data support the notion of an overall tumor-promoting property of C1q. Moreover, the overlapping localization and physical interaction between HYAL2 and gC1qR suggests a potential regulatory effect of gC1qR within a putative HA-C1q macromolecular complex.

  Copyright © 2023 Balduit, Vidergar, Zacchi, Mangogna, Agostinis, Grandolfo, Bottin, Salton, Confalonieri, Rocca, Zanconati, Confalonieri, Kishore, Ghebrehiwet and Bulla.

• Correlative analysis from a phase I clinical trial of intrapleural administration of oncolytic vaccinia virus (Olvi-vec) in patients with malignant pleural mesothelioma. N.K. Chintala, J.K. Choe, E. McGee, et al. 2023;14:1112960. PubMed · Publisher · Free full text

  Abstract

  Background: The attenuated, genetically engineered vaccinia virus has been shown to be a promising oncolytic virus for the treatment of patients with solid tumors, through both direct cytotoxic and immune-activating effects. Whereas systemically administered oncolytic viruses can be neutralized by pre-existing antibodies, locoregionally administered viruses can infect tumor cells and generate immune responses. We conducted a phase I clinical trial to investigate the safety, feasibility and immune activating effects of intrapleural administration of oncolytic vaccinia virus (NCT01766739).

  Methods: Eighteen patients with malignant pleural effusion due to either malignant pleural mesothelioma or metastatic disease (non-small cell lung cancer or breast cancer) underwent intrapleural administration of the oncolytic vaccinia virus using a dose-escalating method, following drainage of malignant pleural effusion. The primary objective of this trial was to determine a recommended dose of attenuated vaccinia virus. The secondary objectives were to assess feasibility, safety and tolerability; evaluate viral presence in the tumor and serum as well as viral shedding in pleural fluid, sputum, and urine; and evaluate anti-vaccinia virus immune response. Correlative analyses were performed on body fluids, peripheral blood, and tumor specimens obtained from pre- and post-treatment timepoints.

  Results: Treatment with attenuated vaccinia virus at the dose of 1.00E+07 plaque-forming units (PFU) to 6.00E+09 PFU was feasible and safe, with no treatment-associated mortalities or dose-limiting toxicities. Vaccinia virus was detectable in tumor cells 2-5 days post-treatment, and treatment was associated with a decrease in tumor cell density and an increase in immune cell density as assessed by a pathologist blinded to the clinical observations. An increase in both effector (CD8+, NK, cytotoxic cells) and suppressor (Tregs) immune cell populations was observed following treatment. Dendritic cell and neutrophil populations were also increased, and immune effector and immune checkpoint proteins (granzyme B, perforin, PD-1, PD-L1, and PD-L2) and cytokines (IFN-γ, TNF-α, TGFβ1 and RANTES) were upregulated.

  Conclusion: The intrapleural administration of oncolytic vaccinia viral therapy is safe and feasible and generates regional immune response without overt systemic symptoms.

  Clinical Trial Registration: https://clinicaltrials.gov/ct2/show/NCT01766739, identifier NCT01766739.

  Copyright © 2023 Chintala, Choe, McGee, Bellis, Saini, Banerjee, Moreira, Zauderer, Adusumilli and Rusch.

• Damage-associated molecular patterns and sensing receptors based molecular subtypes in malignant pleural mesothelioma and implications for immunotherapy. Z. Liu, R. Wan, H. Bai, et al. 2023;14:1104560. PubMed · Publisher · Free full text

  Abstract

  Objectives: Malignant pleural mesothelioma (MPM) is characterized as an incredibly aggressive form of cancer with a dismal diagnosis and a dearth of specific biomarkers and therapeutic options. For MPM patients, the effectiveness of immunotherapy may be influenced by damage-associated molecular pattern (DAMP)-induced immunogenic cell death (ICD).The objective of this work is to create a molecular profile associated with DAMPs to categorize MPM patients and predict their prognosis and response to immunotherapy.

  Methods: The RNA-seq of 397 patients (263 patients with clinical data, 57.2% male, 73.0% over 60 yrs.) were gathered from eight public datasets as a training cohort to identify the DAMPs-associated subgroups of MPMs using K-means analysis. Three validation cohorts of patients or murine were established from TCGA and GEO databases. Comparisons were made across each subtype's immune status, gene mutations, survival prognosis, and predicted response to therapy.

  Results: Based on the DAMPs gene expression, MPMs were categorized into two subtypes: the nuclear DAMPs subtype, which is classified by the upregulation of immune-suppressed pathways, and the inflammatory DAMPs subtype, which is distinguished by the enrichment of proinflammatory cytokine signaling. The inflammatory DAMPs subgroup had a better prognosis, while the nuclear DAMPs subgroup exhibited a worse outcome. In validation cohorts, the subtyping system was effectively verified. We further identified the genetic differences between the two DAMPs subtypes. It was projected that the inflammatory DAMPs subtype will respond to immunotherapy more favorably, suggesting that the developed clustering method may be implemented to predict the effectiveness of immunotherapy.

  Conclusion: We constructed a subtyping model based on ICD-associated DAMPs in MPM, which might serve as a signature to gauge the outcomes of immune checkpoint blockades. Our research may aid in the development of innovative immunomodulators as well as the advancement of precision immunotherapy for MPM.

  Copyright © 2023 Liu, Wan, Bai and Wang.

• Editorial: Focus on malignant pleural mesothelioma immunology and immunotherapy. C. Porta, D. Jean, C. Blanquart. 2023;14:1251384. Editorial PubMed · Publisher · Free full text

• Excess of blood eosinophils prior to therapy correlates with worse prognosis in mesothelioma. M. Willems, A. Scherpereel, E. Wasielewski, et al. 2023;14:1148798. PubMed · Publisher · Free full text

  Abstract

  Background: Only a fraction of patients with malignant pleural mesothelioma (MPM) will respond to chemo- or immunotherapy. For the majority, the condition will irremediably relapse after 13 to 18 months. In this study, we hypothesized that patients' outcome could be correlated to their immune cell profile. Focus was given to peripheral blood eosinophils that, paradoxically, can both promote or inhibit tumor growth depending on the cancer type.

  Methods: The characteristics of 242 patients with histologically proven MPM were retrospectively collected in three centers. Characteristics included overall survival (OS), progression-free survival (PFS), overall response rate (ORR) and disease control rate (DCR). The mean absolute eosinophil counts (AEC) were determined by averaging AEC data sets of the last month preceding the administration of chemo- or immunotherapy.

  Results: An optimal cutoff of 220 eosinophils/µL of blood segregated the cohort into two groups with significantly different median OS after chemotherapy (14 and 29 months above and below the threshold, p = 0.0001). The corresponding two-year OS rates were 28% and 55% in the AEC ≥ 220/µL and AEC < 220/µL groups, respectively. Based on shorter median PFS (8 vs 17 months, p < 0.0001) and reduced DCR (55.9% vs 35.2% at 6 months), the response to standard chemotherapy was significantly affected in the AEC ≥ 220/µL subset. Similar conclusions were also drawn from data sets of patients receiving immune checkpoint-based immunotherapy.

  Conclusion: In conclusion, baseline AEC ≥ 220/µL preceding therapy is associated with worse outcome and quicker relapse in MPM.

  Copyright © 2023 Willems, Scherpereel, Wasielewski, Raskin, Brossel, Fontaine, Grégoire, Halkin, Jamakhani, Heinen, Louis, Duysinx, Hamaidia and Willems.

• Immunotherapy of mesothelioma: the evolving change of a long-standing therapeutic dream. L. Calabrò, G. Bronte, F. Grosso, et al. 2023;14:1333661. Review PubMed · Publisher · Free full text

  Abstract

  Pleural mesothelioma (PM) is an aggressive and rare disease, characterized by a very poor prognosis. For almost two decades, the world standard treatment regimen for unresectable PM has consisted of a platinum-based drug plus pemetrexed, leading to an overall survival of approximately 12 months. The dramatic therapeutic scenario of PM has recently changed with the entry into the clinic of immune checkpoint inhibition, which has proven to be an effective approach to improve the survival of PM patients. The aim of the present review is to provide a comprehensive overview of the most promising immunotherapeutic-based strategies currently under investigation for advanced PM.

  Copyright © 2024 Calabrò, Bronte, Grosso, Cerbone, Delmonte, Nicolini, Mazza, Di Giacomo, Covre, Lofiego, Crinò and Maio.

• Immunotherapy with immune checkpoint inhibitors and predictive biomarkers in malignant mesothelioma: Work still in progress. M. Perrino, F. De Vincenzo, N. Cordua, et al. 2023;14:1121557. Review PubMed · Publisher · Free full text

  Abstract

  Malignant mesothelioma (MM) is a rare and aggressive neoplasm, usually associated with a poor prognosis (5 years survival rate <10%). For unresectable disease, platinum and pemetrexed chemotherapy has been the only standard of care in first line for more than two decades, while no standard treatments have been approved in subsequent lines. Recently, immunotherapy has revolutionized the therapeutic landscape of MM. In fact, the combination of ipilimumab plus nivolumab has been approved in first line setting. Moreover, immune checkpoint inhibitors (ICIs) showed promising results also in second-third line setting after platinum-based chemotherapy. Unfortunately, approximately 20% of patients are primary refractory to ICIs and there is an urgent need for reliable biomarkers to improve patient's selection. Several biological and molecular features have been studied for this goal. In particular, histological subtype (recognized as prognostic factor for MM and predictive factor for chemotherapy response), programmed death ligand 1 (PD-L1) expression, and tumor mutational burden (widely hypothesized as predictive biomarkers for ICIs in several solid tumors) have been evaluated, but with unconclusive results. On the other hand, the deep analysis of tumor infiltrating microenvironment and the improvement in genomic profiling techniques has led to a better knowledge of several mechanisms underlying the MM biology and a greater or poorer immune activation. Consequentially, several potential biomarkers predictive of response to immunotherapy in patients with MM have been identified, also if all these elements need to be further investigated and prospectively validated. In this paper, the main evidences about clinical efficacy of ICIs in MM and the literature data about the most promising predictive biomarkers to immunotherapy are reviewed.

  Copyright © 2023 Perrino, De Vincenzo, Cordua, Borea, Aliprandi, Santoro and Zucali.

• Important functional role of the protein osteopontin in the progression of malignant pleural mesothelioma. E. Digifico, M. Erreni, L. Mannarino, et al. 2023;14:1116430. PubMed · Publisher · Free full text

  Abstract

  Background: Malignant Pleural Mesothelioma (MPM) is an aggressive cancer of the mesothelial lining associated with exposure to airborne non-degradable asbestos fibers. Its poor response to currently available treatments prompted us to explore the biological mechanisms involved in its progression. MPM is characterized by chronic non-resolving inflammation; in this study we investigated which inflammatory mediators are mostly expressed in biological tumor samples from MPM patients, with a focus on inflammatory cytokines, chemokines and matrix components.

  Methods: Expression and quantification of Osteopontin (OPN) was detected in tumor and plasma samples of MPM patients by mRNA, immunohistochemistry and ELISA. The functional role of OPN was investigated in mouse MPM cell lines in vivo using an orthotopic syngeneic mouse model.

  Results: In patients with MPM, the protein OPN was significantly more expressed in tumors than in normal pleural tissues and predominantly produced by mesothelioma cells; plasma levels were elevated in patients and associated with poor prognosis. However, modulation of OPN levels was not significantly different in a series of 18 MPM patients receiving immunotherapy with durvalumab alone or with pembrolizumab in combination with chemotherapy, some of whom achieved a partial clinical response. Two established murine mesothelioma cell lines: AB1 and AB22 of sarcomatoid and epithelioid histology, respectively, spontaneously produced high levels of OPN. Silencing of the OPN gene (Spp1) dramatically inhibited tumor growth in vivo in an orthotopic model, indicating that OPN has an important promoting role in the proliferation of MPM cells. Treatment of mice with anti-CD44 mAb, blocking a major OPN receptor, significantly reduced tumor growth in vivo.

  Conclusion: These results demonstrate that OPN is an endogenous growth factor for mesothelial cells and inhibition of its signaling may be helpful to restrain tumor progression in vivo. These findings have translational potential to improve the therapeutic response of human MPM.

  Copyright © 2023 Digifico, Erreni, Mannarino, Marchini, Ummarino, Anfray, Bertola, Recordati, Pistillo, Roncalli, Bossi, Zucali, D’Incalci, Belgiovine and Allavena.

• Intratumor microbiota as a novel potential prognostic indicator in mesothelioma. F. Pentimalli, M. Krstic-Demonacos, C. Costa, et al. 2023;14:1129513. PubMed · Publisher · Free full text

  Abstract

  Introduction: Despite increased attention on immunotherapy, primarily immune checkpoint blockade, as a therapeutic approach for mesothelioma (MMe), its efficacy and tolerability remain questioned. One potential explanation for different responses to immunotherapy is the gut and intratumor microbiota; however, these remain an underexplored facet of MMe. This article highlights the cancer intratumor microbiota as a novel potential prognostic indicator in MMe.

  Methods: TCGA data on 86 MMe patients from cBioPortal underwent bespoke analysis. Median overall survival was used to divide patients into "Low Survivors" and "High Survivors". Comparison of these groups generated Kaplan-Meier survival analysis, differentially expressed genes (DEGs), and identification of differentially abundant microbiome signatures. Decontamination analysis refined the list of signatures, which were validated as an independent prognostic indicator through multiple linear regression modelling and Cox proportional hazards modelling. Finally, functional annotation analysis on the list of DEGs was performed to link the data together.

  Results: 107 genera signatures were significantly associated with patient survival (positively or negatively), whilst clinical characteristic comparison between the two groups demonstrated that epithelioid histology was more common in "High Survivors" versus biphasic in "Low Survivors". Of the 107 genera, 27 had published articles related to cancer, whilst only one (Klebsiella) had MMe-related published articles. Functional annotation analysis of the DEGs between the two groups highlighted fatty acid metabolism as the most enriched term in "High Survivors", whilst for "Low Survivors" the enriched terms primarily related to cell cycle/division. Linking these ideas and findings together is that the microbiome influences, and is influenced by, lipid metabolism. Finally, to validate the independent prognostic value of the microbiome, multiple linear regression modelling as well as Cox proportional hazards modelling were employed, with both approaches demonstrating that the microbiome was a better prognostic indicator than patient age or stage of the cancer.

  Discussion: The findings presented herein, alongside the very limited literature from scoping searches to validate the genera, highlight the microbiome and microbiota as a potentially rich source of fundamental analysis and prognostic value. Further in vitro studies are needed to elucidate the molecular mechanisms and functional links that may lead to altered survival.

  Copyright © 2023 Pentimalli, Krstic-Demonacos, Costa, Mutti and Bakker.

• Mesothelin expression remodeled the immune-matrix tumor microenvironment predicting the risk of death in patients with malignant pleural mesothelioma. A.N. Qualiotto, C.M. Baldavira, M. Balancin, et al. 2023;14:1268927. PubMed · Publisher · Free full text

  Abstract

  Background: The combination of immunobiological agents with immune checkpoint proteins is a promising treatment for malignant pleural mesothelioma (MPM). Mesothelin and anti-PD-L1 antibody-drug conjugates specifically target malignant neoplastic cells, inhibit the migration and invasion of neoplastic cells, and restore the immune landscape. In this study, we confirmed the importance of mesothelin and examined the relationship between mesothelin and the immune landscape of the tumor microenvironment (TME) in two MPM cohorts.

  Methods: The discovery cohort included 82 MPM cases. Tissue microarray slides were generated, and samples were processed for hematoxylin & eosin staining, immunohistochemistry, and immunofluorescence assays. The relationship between mesothelin, biomarkers of histogenesis, histological aggressiveness, PD-L1, immune cells (CD4, CD8, CD20, CD68), and collagen type I and type V fibers was evaluated by quantitative digital analyses. The outcome was the survival time until death from disease recurrence. The exploratory cohort included 87 malignant mesothelioma (MESO) patients from The Cancer Genome Atlas database.

  Results: Most patients were male (70.7%) with a history of asbestos exposure (53.7%) and with the epithelioid subtype (89%). Surgical resection was performed in 85.4% of patients, and 14.6% received chemotherapy; 59.8% of patients died from disease extension to the mediastinum. Low tumor mesothelin expression was associated with tumor necrosis and nuclear grade 1, whereas high mesothelin expression was significantly associated with the epithelioid histotype and high density of T cells CD8+, macrophages CD68+, and collagen type I fibers. Cox multivariate analysis showed a high risk of death for non-operated patients [hazard ratio (HR), 3.42 (1.15-10.16)] with low tumor mesothelin levels [HR, 2.58 (1.09-6.10)] and high PD-L1 and low infiltration of T cells CD4+ [HR, 3.81 (1.58-9.18)]. In the exploratory cohort, low mesothelin and high COL1A1 and COL5A1 expression were associated with poor overall survival.

  Conclusion: Tumor mesothelin expression associated with the TME immune landscape predicts the risk of death for patients with MPM and could be a new target for immunotherapy in MPM.

  Copyright © 2023 Qualiotto, Baldavira, Balancin, Ab’Saber, Takagaki and Capelozzi.

• The combination of soluble forms of PD-1 and PD-L1 as a predictive marker of PD-1 blockade in patients with advanced cancers: a multicenter retrospective study. T. Kurosaki, K. Chamoto, S. Suzuki, et al. 2023;14:1325462. PubMed · Publisher · Free full text

  Abstract

  Introduction: The clinical relevance of soluble forms of programmed cell death-1 (sPD-1) and programmed cell death-ligand 1 (sPD-L1) remains unclear. We here investigated the relation between the efficacy of PD-1 blockade and pretreatment plasma levels of sPD-1 and sPD-L1 across a broad range of cancer types.

  Methods: We retrospectively analyzed clinical data from 171 patients with advanced solid tumors who received nivolumab or pembrolizumab monotherapy regardless of treatment line. The concentrations of sPD-1 and sPD-L1 were measured with a fully automated immunoassay (HISCL system).

  Results: The study subjects comprised patients with head and neck cancer (n = 50), urothelial cancer (n = 42), renal cell cancer (n = 37), gastric cancer (n = 20), esophageal cancer (n = 10), malignant pleural mesothelioma (n = 6), or microsatellite instability-high tumors (n = 6). High or low levels of sPD-1 or sPD-L1 were not significantly associated with progression-free survival (PFS) or overall survival (OS) for PD-1 blockade in the entire study population. Comparison of treatment outcomes according to combinations of high or low sPD-1 and sPD-L1 levels, however, revealed that patients with low sPD-1 and high sPD-L1 concentrations had a significantly poorer PFS (HR of 1.79 [95% CI, 1.13-2.83], p = 0.01) and a tendency toward poorer OS (HR of 1.70 [95% CI, 0.99-2.91], p = 0.05) compared with all other patients.

  Conclusion: Our findings suggest that the combination of low sPD-1 and high sPD-L1 levels is a potential negative biomarker for PD-1 blockade therapy.

  Copyright © 2023 Kurosaki, Chamoto, Suzuki, Kanemura, Mitani, Tanaka, Kawakami, Kishimoto, Haku, Ito, Sato, Suminaka, Yamaki, Chiba, Yaguchi, Omori, Kobayashi, Nakagawa, Honjo and Hayashi.

• Three distinct mechanisms underlying human γδ T cell-mediated cytotoxicity against malignant pleural mesothelioma. Y. Umeyama, H. Taniguchi, H. Gyotoku, et al. 2023;14:1058838. PubMed · Publisher · Free full text

  Abstract

  Introduction: Malignant pleural mesothelioma (MPM) is a rare and highly aggressive thoracic tumor with poor prognosis and limited therapeutic options. Although immune checkpoint inhibitors exhibit a promising effect in some patients with unresectable MPM in clinical trials, the majority of MPM patients show only modest response rates to the currently available treatments. It is thus imperative to develop novel and innovative therapeutic modalities for MPM, including immune effector cell-based therapies.

  Methods: γδ T cells were expanded using tetrakis-pivaloyloxymethyl 2-(thiazole-2-ylamino) ethylidene-1,1-bisphosphonate (PTA) and interleukin-2, and the therapeutic potential of γδ T cells was examined through analyzing cell surface markers and cellular cytotoxicity against MPM in vitro using a europium chelate-based time-resolved fluorescence assay system and a luciferase-based luminescence assay system.

  Results And Discussion: We successfully expanded γδ T cells from peripheral blood mononuclear cells of healthy donors and MPM patients. γδ T cells expressed natural killer receptors such as NKG2D and DNAM-1 and exhibited a moderate level of cytotoxicity to MPM cells in the absence of antigens. The inclusion of PTA, (E)-4-hydroxy-3- methylbut-2-enyl diphosphate (HMBPP) or zoledronic acid (ZOL) induced a TCR-dependent cytotoxicity in γδ T cells and secreted interferon-γ (IFN-γ). In addition, γδ T cells expressing CD16 exhibited a significant level of cytotoxicity against MPM cells in the presence of an anti-epidermal growth factor receptor (EGFR) mAb, at lower concentrations than in clinical settings, whereas a detectable level of IFN-γ was not produced. Taken together, γδ T cells showed cytotoxic activity against MPM in three distinct mechanisms through NK receptors, TCRs and CD16. Since major histocompatibility complex (MHC) molecules are not involved in the recognition, both autologous and allogeneic γδ T cells could be used for the development of γδ T cell-based adoptive immunotherapy for MPM.

  Copyright © 2023 Umeyama, Taniguchi, Gyotoku, Senju, Tomono, Takemoto, Yamaguchi, Tagod, Iwasaki, Tanaka and Mukae.

• Comprehensive Testing of Chemotherapy and Immune Checkpoint Blockade in Preclinical Cancer Models Identifies Additive Combinations. N. Principe, W.J. Aston, D.E. Hope, et al. 2022;13:872295. PubMed · Publisher · Free full text

  Abstract

  Antibodies that target immune checkpoints such as cytotoxic T lymphocyte antigen 4 (CTLA-4) and the programmed cell death protein 1/ligand 1 (PD-1/PD-L1) are now a treatment option for multiple cancer types. However, as a monotherapy, objective responses only occur in a minority of patients. Chemotherapy is widely used in combination with immune checkpoint blockade (ICB). Although a variety of isolated immunostimulatory effects have been reported for several classes of chemotherapeutics, it is unclear which chemotherapeutics provide the most benefit when combined with ICB. We investigated 10 chemotherapies from the main canonical classes dosed at the clinically relevant maximum tolerated dose in combination with anti-CTLA-4/anti-PD-L1 ICB. We screened these chemo-immunotherapy combinations in two murine mesothelioma models from two different genetic backgrounds, and identified chemotherapies that produced additive, neutral or antagonistic effects when combined with ICB. Using flow cytometry and bulk RNAseq, we characterized the tumor immune milieu in additive chemo-immunotherapy combinations. 5-fluorouracil (5-FU) or cisplatin were additive when combined with ICB while vinorelbine and etoposide provided no additional benefit when combined with ICB. The combination of 5-FU with ICB augmented an inflammatory tumor microenvironment with markedly increased CD8+ T cell activation and upregulation of IFNγ, TNFα and IL-1β signaling. The effective anti-tumor immune response of 5-FU chemo-immunotherapy was dependent on CD8+ T cells but was unaffected when TNFα or IL-1β cytokine signaling pathways were blocked. Our study identified additive and non-additive chemotherapy/ICB combinations and suggests a possible role for increased inflammation in the tumor microenvironment as a basis for effective combination therapy.

  Copyright © 2022 Principe, Aston, Hope, Tilsed, Fisher, Boon, Dick, Chin, McDonnell, Nowak, Lake, Chee and Lesterhuis.

• Deep dive into the immune response against murine mesothelioma permits design of novel anti-mesothelioma therapeutics. E. Stern, S. Caruso, C. Meiller, et al. 2022;13:1026185. PubMed · Publisher · Free full text

  Abstract

  Given the need to improve the efficacy of standard-of-care immunotherapy (anti-CTLA-4 + anti-PD-1) in human malignant pleural mesothelioma (hMPM), we thoroughly characterized the immunobiology of the AB12 murine mesothelioma (MM) model, aiming to increase its accuracy in predicting the response of hMPM to immunotherapy and in designing novel anti-hMPM treatments. Specifically, we used immunologic, transcriptomic and survival analyses, to synchronize the MM tumor growth phases and immune evolution with the histo-molecular and immunological characteristics of hMPM while also determining the anti-MM efficacy of standard-of-care anti-hMPM immunotherapy as a benchmark that novel therapeutics should meet. We report that early-, intermediate- and advanced- AB12 tumors are characterized by a bell-shaped anti-tumor response that peaks in intermediate tumors and decays in advanced tumors. We further show that intermediate- and advanced- tumors match with immune active ("hot") and immune inactive ("cold") hMPM respectively, and that they respond to immunotherapy in a manner that corresponds well with its performance in real-life settings. Finally, we show that in advanced tumors, addition of cisplatin to anti CTLA-4 + anti PD-1 can extend mice survival and invigorate the decaying anti-tumor response. Therefore, we highlight this triple combination as a worthy candidate to improve clinical outcomes in hMPM.

  Copyright © 2023 Stern, Caruso, Meiller, Mishalian, Hirsch, Bayard, Tadmor, Wald, Jean and Wald.

• Population pharmacokinetic models of anti-PD-1 mAbs in patients with multiple tumor types: A systematic review. J. Shang, L. Huang, J. Huang, et al. 2022;13:871372. Systematic review PubMed · Publisher · Free full text

  Abstract

  Aims And Background: A number of population pharmacokinetic (PPK) models of anti-programmed cell death-1 (PD-1) monoclonal antibodies (mAbs) in multiple tumor types have been published to characterize the influencing factors of their pharmacokinetics. This review described PPK models of anti-PD-1 mAbs that investigate the magnitude and types of covariate effects in PK parameters, provide a reference for building PPK models of other anti-PD-1 mAbs, and identify areas requiring additional research to facilitate the application of PPK models.

  Methods: A systematic search for analyses of PPK models of eleven anti-PD-1 mAbs on the market that were carried out in humans was conducted using PubMed, Embase, and the Cochrane Library. The search covered the period from the inception of the databases to April 2022.

  Results: Currently, there are fourteen analyses on PPK models of anti-PD-1 mAbs summarized in this review, including seven models that refer to nivolumab, four referring to pembrolizumab, one referring to cemiplimab, one referring to camrelizumab, and one referred to dostarlimab. Most analyses described the pharmacokinetics of anti-PD-1 mAbs with a two-compartment model with time-varying clearance (CL) and a sigmoidal maximum effect. The estimated CL and volume of distribution in the central (VC) ranged from 0.179 to 0.290 L/day and 2.98 to 4.46 L, respectively. The median (range) of interindividual variability (IIV) for CL and VC was 30.9% (8.7%-50.8%) and 29.0% (4.32%-40.7%), respectively. The commonly identified significant covariates were body weight (BW) on CL and VC, and albumin (ALB), tumor type, sex, and performance status (PS) on CL. Other less assessed significant covariates included lactate dehydrogenase (LDH), immunoglobulin G (IgG), ipilimumab coadministration (IPICO) on CL, and body mass index (BMI), malignant pleural mesothelioma (MESO) on VC.

  Conclusion: This review provides detailed information about the characteristics of PPK models of anti-PD-1 mAbs, the effects of covariates on PK parameters, and the current status of the application of the models. ALB, BW, specific tumor type, sex, and PS should be considered for the future development of the PPK model of anti-PD-1 mAbs. Other potential covariates that were assessed less frequently but still have significance (e.g., LDH, IgG, and IPICO) should not be ignored. Thus, further research and thorough investigation are needed to assess new or potential covariates, which will pave the way for personalized anti-PD-1 mAbs therapy.

  Copyright © 2022 Shang, Huang, Huang, Ren, Liu and Feng.

• The STING agonist, DMXAA, reduces tumor vessels and enhances mesothelioma tumor antigen presentation yet blunts cytotoxic T cell function in a murine model. P.T. Graham, A.K. Nowak, S.M.J. Cornwall, et al. 2022;13:969678. PubMed · Publisher · Free full text

  Abstract

  We assessed the murine Stimulator of Interferon Genes (STING) agonist, DMXAA, for anti-mesothelioma potential using the AE17-sOVA model that expresses ovalbumin (OVA) as a neo tumor antigen. Dose response experiments alongside testing different routes of administration identified a safe effective treatment regimen that induced 100% cures in mice with small or large tumors. Three doses of 25mg/kg DMXAA given intra-tumorally every 9 days induced tumor regression and long-term survival (>5 months). Re-challenge experiments showed that tumor-free mice developed protective memory. MTT and propidium-iodide assays showed that DMXAA exerted direct cytotoxic effects at doses >1mg/ml on the murine AE17 and AB1 mesothelioma cell lines. In-vivo studies using a CFSE-based in-vivo proliferation assay showed that DMXAA improved tumor-antigen presentation in tumor-draining lymph nodes, evidenced by OVA-specific OT-1 T cells undergoing more divisions. An in-vivo cytotoxic T lymphocyte (CTL) assay showed that DMXAA blunted the lytic quality of CTLs recognizing the dominant (SIINFEKL) and a subdominant (KVVRFDKL) OVA epitopes. DMXAA reduced tumor vessel size in-vivo and although the proportion of T cells infiltrating tumors reduced, the proportion of tumor-specific T cells increased. These data show careful dosing and treatment protocols reduce mesothelioma cell viability and modulate tumor vessels such that tumor-antigen specific CTLs access the tumor site. However, attempts to enhance DMXAA-induced anti-tumor responses by combination with an agonist anti-CD40 antibody or IL-2 reduced efficacy. These proof-of-concept data suggest that mesothelioma patients could benefit from treatment with a STING agonist, but combination with immunotherapy should be cautiously undertaken.

  Copyright © 2022 Graham, Nowak, Cornwall, Larma and Nelson.

• Celiac Disease After Administration of Immune Checkpoint Inhibitors: A Case Report. J. Leblanc, S. Hoibian, A. Boucraut, et al. 2021;12:799666. Case report PubMed · Publisher · Free full text

  Abstract

  Immune checkpoint inhibitors (ICI) reinvigorate the immune system to recognize and destroy tumor cells. Because of this biological mechanism, patients might develop autoimmune toxicities, notably in the digestive tract (most frequently, hepatitis or colitis). A 70-year-old man with relapsed mesothelioma was treated with nivolumab in 3rd line. He was hospitalized for watery and foul-smelling diarrhea. He underwent gastrointestinal endoscopy, showing duodenitis and villous atrophy and measurement of serum IgA antibodies to tissue transglutaminase (tTG-IgA+), leading to the diagnosis of ICI-induced celiac disease. He was treated with steroids, proton pump inhibitors, and a gluten-free diet. If ICI-induced celiac disease is rare in the literature, increasing reports suggest that celiac disease might represent an underestimated ICI toxicity. This case highlights the necessity of complementary investigation (including tTG-IgA and endoscopic biopsies) in patients with atypical digestive symptoms during immunotherapy.

  Copyright © 2021 Leblanc, Hoibian, Boucraut, Ratone, Stoffaes, Dano, Louvel-Perrot, Chanez, Chretien, Madroszyk and Rochigneux.

• Efficacy of Immune Checkpoint Inhibitors in Rare Tumours: A Systematic Review. F. Petrelli, F. Consoli, A. Ghidini, et al. 2021;12:720748. Meta-analysis · Systematic review PubMed · Publisher · Free full text

  Abstract

  Background: Rare cancers, as defined by the European Union, occur in fewer than 15 out of 100,000 people each year. The International Rare Cancer Consortium defines rare cancer incidence as less than six per 100,000 per year. There is a growing number of reports of the efficacy of immune checkpoint inhibitor (ICI) therapy in patients with rare tumours, and hence, we conducted a comprehensive review to summarise and analyse the available literature.

  Methods: A literature search of PubMed was performed on January 31, 2021, using the following ICI names as keywords: ipilimumab, tremelimumab, cemiplimab, nivolumab, pembrolizumab, avelumab, atezolizumab, and durvalumab. Studies on patients with rare tumours who were being treated with ICIs were included. We plotted the overall response rate against the corresponding median survival across a variety of cancer types using linear regression.

  Results: From 1,255 publications retrieved during the primary search, 62 publications were selected (with a total of 4,620 patients). Only four were randomised trials. A minority were first-line studies, while the remaining were studies in which ICIs were delivered as salvage therapy in pretreated patients. There was a good correlation between response rate and overall survival (Spearman R2 >0.9) in skin cancers, mesothelioma, and sarcomas.

  Conclusions: Treatment of advanced-stage rare tumours with ICI therapy was found to be associated with significant activity in some orphan diseases (e.g., Merkel cell carcinoma) and hepatocellular carcinoma. Several ongoing prospective clinical trials will expand the knowledge on the safety and efficacy of ICI therapy in patients with these rare cancers.

  Copyright © 2021 Petrelli, Consoli, Ghidini, Perego, Luciani, Mercurio, Berruti and Grisanti.

• Monocytic Ontogeny of Regenerated Macrophages Characterizes the Mesotheliomagenic Responses to Carbon Nanotubes. M. Orsi, M. Palmai-Pallag, Y. Yakoub, et al. 2021;12:666107. PubMed · Publisher · Free full text

  Abstract

  Macrophages are not only derived from circulating blood monocytes or embryonic precursors but also expand by proliferation. The origin determines macrophage fate and functions in steady state and pathological conditions. Macrophages predominantly infiltrate fibre-induced mesothelioma tumors and contribute to cancer development. Here, we revealed their ontogeny by comparing the response to needle-like mesotheliomagenic carbon nanotubes (CNT-7) with tangled-like non-mesotheliomagenic CNT-T. In a rat peritoneal cavity model of mesothelioma, both CNT induced a rapid macrophage disappearance reaction (MDR) of MHCIIlow resident macrophages generating an empty niche available for macrophage repopulation. Macrophage depletion after mesotheliomagenic CNT-7 was followed by a substantial inflammatory reaction, and macrophage replenishment completed after 7 days. Thirty days after non-mesotheliomagenic CNT-T, macrophage repopulation was still incomplete and accompanied by a limited inflammatory reaction. Cell depletion experiments, flow cytometry and RNA-seq analysis demonstrated that, after mesotheliomagenic CNT-7 exposure, resident macrophages were mainly replaced by an influx of monocytes, which differentiated locally into MHCIIhigh inflammatory macrophages. In contrast, the low inflammatory response induced by CNT-T was associated by the accumulation of self-renewing MHCIIlow macrophages that initially derive from monocytes. In conclusion, the mesotheliomagenic response to CNT specifically relies on macrophage niche recolonization by monocyte-derived inflammatory macrophages. In contrast, the apparent homeostasis after non-mesotheliomagenic CNT treatment involves a macrophage regeneration by proliferation. Macrophage depletion and repopulation are thus decisive events characterizing the carcinogenic activity of particles and fibres.

  Copyright © 2021 Orsi, Palmai-Pallag, Yakoub, Ibouraadaten, De Beukelaer, Bouzin, Bearzatto, Ambroise, Gala, Brusa, Lison and Huaux.

• Development of ImmTOR Tolerogenic Nanoparticles for the Mitigation of Anti-drug Antibodies. T.K. Kishimoto. 2020;11:969. Review PubMed · Publisher · Free full text

  Abstract

  The development of anti-drug antibodies (ADAs) is a common cause for treatment failure and hypersensitivity reactions for many biologics. The focus of this review is the development of ImmTOR, a platform technology designed to prevent the formation of ADAs that can be applied broadly across a wide variety of biologics by inducing immunological tolerance with ImmTOR nanoparticles encapsulating rapamycin. The induction of tolerance is antigen-specific and dependent on the incorporation of rapamycin in nanoparticles and the presence of the antigen at the time of administration of ImmTOR. Evidence for the induction of specific immune tolerance vs. general immune suppression is supported by the findings that: (1) ImmTOR induces regulatory T cells specific to the co-administered antigen; (2) tolerance can be transferred by adoptive transfer of splenocytes from treated animals to naïve recipients; (3) the tolerance is durable to subsequent challenge with antigen alone; and (4) animals tolerized to a specific antigen are capable of responding to an unrelated antigen. ImmTOR nanoparticles can be added to new or existing biologics without the need to modify or reformulate the biologic drug. The ability of ImmTOR to mitigate the formation of ADAs has been demonstrated for coagulation factor VIII in a mouse model of hemophilia A, an anti-TNFα monoclonal antibody in a mouse model of inflammatory arthritis, pegylated uricase in hyperuricemic mice and in non-human primates, acid alpha-glucosidase in a mouse model of Pompe disease, recombinant immunotoxin in a mouse model of mesothelioma, and adeno-associated vectors in a model of repeat dosing of gene therapy vectors in mice and in non-human primates. Human proof-of concept for the mitigation of ADAs has been demonstrated with SEL-212, a combination product consisting of ImmTOR + pegadricase, a highly immunogenic enzyme therapy for the treatment of gout. ImmTOR represents a promising approach to preventing the formation of ADAs to a broad range of biologic drugs.

  Copyright © 2020 Kishimoto.

• Immunogenicity of Immunotoxins Containing Pseudomonas Exotoxin A: Causes, Consequences, and Mitigation. R. Mazor, I. Pastan. 2020;11:1261. Review PubMed · Publisher · Free full text

  Abstract

  Immunotoxins are cytolytic fusion proteins developed for cancer therapy, composed of an antibody fragment that binds to a cancer cell and a protein toxin fragment that kills the cell. Pseudomonas exotoxin A (PE) is a potent toxin that is used for the killing moiety in many immunotoxins. Moxetumomab Pasudotox (Lumoxiti) contains an anti-CD22 Fv and a 38 kDa portion of PE. Lumoxiti was discovered in the Laboratory of Molecular Biology at the U.S. National Cancer Institute and co-developed with Medimmune/AstraZeneca to treat hairy cell leukemia. In 2018 Lumoxiti was approved by the US Food and Drug Administration for the treatment of drug-resistant Hairy Cell Leukemia. Due to the bacterial origin of the killing moiety, immunotoxins containing PE are highly immunogenic in patients with normal immune systems, but less immunogenic in patients with hematologic malignancies, whose immune systems are often compromised. LMB-100 is a de-immunized variant of the toxin with a humanized antibody that targets mesothelin and a PE toxin that was rationally designed for diminished reactivity with antibodies and B cell receptors. It is now being evaluated in clinical trials for the treatment of mesothelioma and pancreatic cancer and is showing somewhat diminished immunogenicity compared to its un modified parental counterpart. Here we review the immunogenicity of the original and de-immunized PE immunotoxins in mice and patients, the development of anti-drug antibodies (ADAs), their impact on drug availability and their effect on clinical efficacy. Efforts to mitigate the immunogenicity of immunotoxins and its impact on immunogenicity will be described including rational design to identify, remove, or suppress B cell or T cell epitopes, and combination of immunotoxins with immune modulating drugs.

  Copyright © 2020 Mazor and Pastan.

• Mesothelioma in Familial Mediterranean Fever With Colchicine Intolerance: A Case Report and Literature Review. R. Talerico, C. Cardillo, F. De Vito, et al. 2020;11:889. Case report PubMed · Publisher · Free full text

  Abstract

  A 65-year-old Italian physician affected by Familial Mediterranean fever (FMF) was hospitalized due to progressive abdominal enlargement, which had begun 6 months before admission. Physical examination revealed ascites and bilateral leg edema. Abdominal CT scan showed ascitic fluid and extensive multiple peritoneal implants; peritoneal CT-guided biopsy revealed an epithelial-type malignant mesothelioma. The patient's past medical history revealed recurrent episodes of abdominal pain and fever from the age of 2. Clinical diagnosis of FMF was suspected at the age of 25, while genetic analysis, performed at the age of 50, confirmed homozygosity for the M694I mutation in the MEFV gene. Treatment with the first line FMF drug colchicine was started and stopped several times because of worsened leukopenia. The patient in fact had a history of asymptomatic leukopenia/lymphopenia from an early age; the intake of colchicine aggravated his pre-existing problem until the definitive suspension of the drug. As for second-line drugs, canakinumab was first prescribed, but due to prescription issues, it was not possible to be administered. When he was given anakinra, there was a worsening of leukopenia leading to septic fever. Systematic literature review indicates that, in most cases, recurrent peritoneal inflammation results in benign peritoneal fibrosis or less commonly in encapsulating peritonitis. There are only a few reported cases of recurrent peritoneal inflammation progressing from FMF to peritoneal mesothelioma (MST). In such cases, intolerance to colchicine or its erratic intake may lead to long-term recurrent inflammation, which usually precedes the development of the tumor, while pre-existing leukopenia, as in our patient, could also be a factor promoting or accelerating the tumor progression. In conclusion, we suggest that in the presence of intolerance or resistance to colchicine, interleukin (IL)-1 inhibition could suppress peritoneal inflammation and prevent MSTs.

  Copyright © 2020 Talerico, Cardillo, De Vito, Schinzari, Soldato, Giustiniani, Verrecchia and Manna.

2010s

• Biological Activities of Secretory RNases: Focus on Their Oligomerization to Design Antitumor Drugs. G. Gotte, M. Menegazzi. 2019;10:2626. Review PubMed · Publisher · Free full text

  Abstract

  Ribonucleases (RNases) are a large number of enzymes gathered into different bacterial or eukaryotic superfamilies. Bovine pancreatic RNase A, bovine seminal BS-RNase, human pancreatic RNase 1, angiogenin (RNase 5), and amphibian onconase belong to the pancreatic type superfamily, while binase and barnase are in the bacterial RNase N1/T1 family. In physiological conditions, most RNases secreted in the extracellular space counteract the undesired effects of extracellular RNAs and become protective against infections. Instead, if they enter the cell, RNases can digest intracellular RNAs, becoming cytotoxic and having advantageous effects against malignant cells. Their biological activities have been investigated either in vitro, toward a number of different cancer cell lines, or in some cases in vivo to test their potential therapeutic use. However, immunogenicity or other undesired effects have sometimes been associated with their action. Nevertheless, the use of RNases in therapy remains an appealing strategy against some still incurable tumors, such as mesothelioma, melanoma, or pancreatic cancer. The RNase inhibitor (RI) present inside almost all cells is the most efficacious sentry to counteract the ribonucleolytic action against intracellular RNAs because it forms a tight, irreversible and enzymatically inactive complex with many monomeric RNases. Therefore, dimerization or multimerization could represent a useful strategy for RNases to exert a remarkable cytotoxic activity by evading the interaction with RI by steric hindrance. Indeed, the majority of the mentioned RNases can hetero-dimerize with antibody derivatives, or even homo-dimerize or multimerize, spontaneously or artificially. This can occur through weak interactions or upon introducing covalent bonds. Immuno-RNases, in particular, are fusion proteins representing promising drugs by combining high target specificity with easy delivery in tumors. The results concerning the biological features of many RNases reported in the literature are described and discussed in this review. Furthermore, the activities displayed by some RNases forming oligomeric complexes, the mechanisms driving toward these supramolecular structures, and the biological rebounds connected are analyzed. These aspects are offered with the perspective to suggest possible efficacious therapeutic applications for RNases oligomeric derivatives that could contemporarily lack, or strongly reduce, immunogenicity and other undesired side-effects.

  Copyright © 2019 Gotte and Menegazzi.

• Microenvironment-Dependent Gradient of CTL Exhaustion in the AE17sOVA Murine Mesothelioma Tumor Model. J.L. Hope, P.I. Spantidea, C.H. Kiernan, et al. 2019;10:3074. PubMed · Publisher · Free full text

  Abstract

  The immune system, and in particular, cytotoxic CD8+ T cells (CTLs), plays a vital part in the prevention and elimination of tumors. In many patients, however, CTL-mediated tumor killing ultimately fails in the clearance of cancer cells resulting in disease progression, in large part due to the progression of effector CTL into exhausted CTL. While there have been major breakthroughs in the development of CTL-mediated "reinvigoration"-driven immunotherapies such as checkpoint blockade therapy, there remains a need to better understand the drivers behind the development of T cell exhaustion. Our study highlights the unique differences in T cell exhaustion development in tumor-specific CTL which arises over time in a mouse model of mesothelioma. Importantly, we also show that peripheral tumor-specific T cells have a unique expression profile compared to exhausted tumor-infiltrating CTL at a late-stage of tumor progression in mice. Together, these data suggest that greater emphasis should be placed on understanding contributions of individual microenvironments in the development of T cell exhaustion.

  Copyright © 2020 Hope, Spantidea, Kiernan, Stairiker, Rijsbergen, van Meurs, Brouwers-Haspels, Mueller, Nelson, Bradley, Aerts and Katsikis.

• Prognostic Implications of the Complement Protein C1q in Gliomas. A. Mangogna, B. Belmonte, C. Agostinis, et al. 2019;10:2366. PubMed · Publisher · Free full text

  Abstract

  The contribution of the complement system in the pathophysiology of brain cancers has been recently considered in light of its well-known involvement in carcinogenesis. Complement system represents an important component of the inflammatory response, which acts as a functional bridge between the innate and adaptive immune response. C1q, the first recognition subcomponent of the complement classical pathway, has recently been shown to be involved in a range of pathophysiological functions that are not dependent on complement activation. C1q is expressed in the microenvironment of various types of human tumors, including melanoma, prostate, mesothelioma, and ovarian cancers, where it can exert a protective or a harmful effect on cancer progression. Despite local synthesis of C1q in the central nervous system, the involvement of C1q in glioma pathogenesis has been poorly investigated. We, therefore, performed a bioinformatics analysis, using Oncomine dataset and UALCAN database in order to assess whether the expression of the genes encoding for the three chains of C1q (C1qA, C1qB, and C1qC) could serve as a potential prognostic marker for gliomas. The obtained results were then validated using an independent glioma cohort from the Chinese Glioma Genome Atlas datasets. Our bioinformatics analysis, coupled with immunohistochemistry and fluorescence microscopy, appears to suggest a positive correlation between higher levels of C1q expression and unfavorable prognosis in a diverse grade of gliomas.

  Copyright © 2019 Mangogna, Belmonte, Agostinis, Zacchi, Iacopino, Martorana, Rodolico, Bonazza, Zanconati, Kishore and Bulla.

• Autologous Dendritic Cell Therapy in Mesothelioma Patients Enhances Frequencies of Peripheral CD4 T Cells Expressing HLA-DR, PD-1, or ICOS. P.L. de Goeje, Y. Klaver, M.E.H. Kaijen-Lambers, et al. 2018;9:2034. PubMed · Publisher · Free full text

  Abstract

  Introduction: Malignant pleural mesothelioma (MPM) is a malignancy with a very poor prognosis for which new treatment options are urgently needed. We have previously shown that dendritic cell (DC) immunotherapy provides a clinically feasible treatment option. In the current study, we set out to assess the immunological changes induced by DC immunotherapy in peripheral blood of MPM patients. Methods: Peripheral blood was collected from nine patients enrolled in a phase I dose escalation study, before and after treatment with DCs that were pulsed with an allogeneic tumor lysate preparation consisting of a mixture of five cultured mesothelioma cell lines. We used immune profiling by multiplex flow cytometry to characterize different populations of immune cells. In particular, we determined frequencies of T cell subsets that showed single and combinatorial expression of multiple markers that signify T cell activation, maturation and inhibition. Therapy-induced T cell reactivity was assessed in peptide/MHC multimer stainings using mesothelin as a prototypic target antigen with confirmed expression in the clinical tumor lysate preparation. T cell receptor (TCR) diversity was evaluated by TCRB gene PCR assays. Results: We observed an increase in the numbers of B cells, CD4 and CD8 T cells, but not NK cells at 6 weeks post-treatment. The increases in B and T lymphocytes were not accompanied by major changes in T cell reactivity toward mesothelin nor in TCRB diversity. Notably, we did observe enhanced proportions of CD4 T cells expressing HLA-DR, PD-1 (at 2 weeks after onset of treatment) and ICOS (6 weeks) and a CD8 T cell population expressing LAG3 (2 weeks). Discussion: DC immunotherapy using allogeneic tumor lysate resulted in enhanced frequencies of B cells and T cells in blood. We did not detect a skewed antigen-reactivity of peripheral CD8 T cells. Interestingly, frequencies of CD4 T cells expressing activation markers and PD-1 were increased. These findings indicate a systemic activation of the adaptive immune response and may guide future immune monitoring studies of DC therapies.

• Macrophage Recognition of Crystals and Nanoparticles. M. Nakayama. 2018;9:103. Review PubMed · Publisher · Free full text

  Abstract

  Inhalation of exogenous crystals such as silica, asbestos, and carbon nanotubes can cause lung fibrosis and cancer. Endogenous crystals such as monosodium urate, cholesterol, and hydroxyapatite are associated with pathogenesis of gout, atherosclerosis, and osteoarthritis, respectively. These crystal-associated-inflammatory diseases are triggered by the macrophage NLRP3 inflammasome activation and cell death. Therefore, it is important to understand how macrophages recognize crystals. However, it is unlikely that macrophages have evolutionally acquired receptors specific for crystals or recently emerged nanoparticles. Several recent studies have reported that some crystal particles are negatively charged and are recognized by scavenger receptor family members in a charge-dependent manner. Alternatively, a model for receptor-independent phagocytosis of crystals has also been proposed. This review focuses on the mechanisms by which macrophages recognize crystals and nanoparticles.

• Chondroitin Sulfate Proteoglycan 4 and Its Potential As an Antibody Immunotherapy Target across Different Tumor Types. K.M. Ilieva, A. Cheung, S. Mele, et al. 2017;8:1911. Review PubMed · Publisher · Free full text

  Abstract

  Overexpression of the chondroitin sulfate proteoglycan 4 (CSPG4) has been associated with the pathology of multiple types of such as melanoma, breast cancer, squamous cell carcinoma, mesothelioma, neuroblastoma, adult and pediatric sarcomas, and some hematological cancers. CSPG4 has been reported to exhibit a role in the growth and survival as well as in the spreading and metastasis of tumor cells. CSPG4 is overexpressed in several malignant diseases, while it is thought to have restricted and low expression in normal tissues. Thus, CSPG4 has become the target of numerous anticancer treatment approaches, including monoclonal antibody-based therapies. This study reviews key potential anti-CSPG4 antibody and immune-based therapies and examines their direct antiproliferative/metastatic and immune activating mechanisms of action.

• Complement Protein C1q Binds to Hyaluronic Acid in the Malignant Pleural Mesothelioma Microenvironment and Promotes Tumor Growth. C. Agostinis, R. Vidergar, B. Belmonte, et al. 2017;8:1559. PubMed · Publisher · Free full text

  Abstract

  C1q is the first recognition subcomponent of the complement classical pathway, which acts toward the clearance of pathogens and apoptotic cells. C1q is also known to modulate a range of functions of immune and non-immune cells, and has been shown to be involved in placental development and sensorial synaptic pruning. We have recently shown that C1q can promote tumor by encouraging their adhesion, migration, and proliferation in addition to angiogenesis and metastasis. In this study, we have examined the role of human C1q in the microenvironment of malignant pleural mesothelioma (MPM), a rare form of cancer commonly associated with exposure to asbestos. We found that C1q was highly expressed in all MPM histotypes, particularly in epithelioid rather than in sarcomatoid histotype. C1q avidly bound high and low molecular weight hyaluronic acid (HA) via its globular domain. C1q bound to HA was able to induce adhesion and proliferation of mesothelioma cells (MES) via enhancement of ERK1/2, SAPK/JNK, and p38 phosphorylation; however, it did not activate the complement cascade. Consistent with the modular organization of the globular domain, we demonstrated that C1q may bind to HA through ghA module, whereas it may interact with human MES through the ghC. In conclusion, C1q highly expressed in MPM binds to HA and enhances the tumor growth promoting cell adhesion and proliferation. These data can help develop novel diagnostic markers and molecular targets for MPM.

• Hyaluronan synthase 1: a mysterious enzyme with unexpected functions. H. Siiskonen, S. Oikari, S. Pasonen-Seppänen, et al. 2015;6:43. Review PubMed · Publisher · Free full text

  Abstract

  Hyaluronan synthase 1 (HAS1) is one of three isoenzymes responsible for cellular hyaluronan synthesis. Interest in HAS1 has been limited because its role in hyaluronan production seems to be insignificant compared to the two other isoenzymes, HAS2 and HAS3, which have higher enzymatic activity. Furthermore, in most cell types studied so far, the expression of its gene is low and the enzyme requires high concentrations of sugar precursors for hyaluronan synthesis, even when overexpressed in cell cultures. Both expression and activity of HAS1 are induced by pro-inflammatory factors like interleukins and cytokines, suggesting its involvement in inflammatory conditions. Has1 is upregulated in states associated with inflammation, like atherosclerosis, osteoarthritis, and infectious lung disease. In addition, both full length and splice variants of HAS1 are expressed in malignancies like bladder and prostate cancers, multiple myeloma, and malignant mesothelioma. Interestingly, immunostainings of tissue sections have demonstrated the role of HAS1 as a poor predictor in breast cancer, and is correlated with high relapse rate and short overall survival. Utilization of fluorescently tagged proteins has revealed the intracellular distribution pattern of HAS1, distinct from other isoenzymes. In all cell types studied so far, a high proportion of HAS1 is accumulated intracellularly, with a faint signal detected on the plasma membrane and its protrusions. Furthermore, the pericellular hyaluronan coat produced by HAS1 is usually thin without induction by inflammatory agents or glycemic stress and depends on CD44-HA interactions. These specific interactions regulate the organization of hyaluronan into a leukocyte recruiting matrix during inflammatory responses. Despite the apparently minor enzymatic activity of HAS1 under normal conditions, it may be an important factor under conditions associated with glycemic stress like metabolic syndrome, inflammation, and cancer.

• Malarial pigment hemozoin and the innate inflammatory response. M. Olivier, K. Van Den Ham, M.T. Shio, et al. 2014;5:25. Review PubMed · Publisher · Free full text

  Abstract

  Malaria is a deadly infectious disease caused by the intraerythrocytic protozoan parasite Plasmodium. The four species of Plasmodium known to affect humans all produce an inorganic crystal called hemozoin (HZ) during the heme detoxification process. HZ is released from the food vacuole into circulation during erythrocyte lysis, while the released parasites further infect additional naive red blood cells. Once in circulation, HZ is rapidly taken up by circulating monocytes and tissue macrophages, inducing the production of pro-inflammatory mediators, such as interleukin-1β (IL-1β). Over the last few years, it has been reported that HZ, similar to uric acid crystals, asbestos, and silica, is able to trigger IL-1β production via the activation of the NOD-like receptor containing pyrin domain 3 (NLRP3) inflammasome complex. Additionally, recent findings have shown that host factors, such as fibrinogen, have the ability to adhere to free HZ and modify its capacity to activate host immune cells. Although much has been discovered regarding NLRP3 inflammasome induction, the mechanism through which this intracellular multimolecular complex is activated remains unclear. In the present review, the most recent discoveries regarding the capacity of HZ to trigger this innate immune complex as well as the impact of HZ on several other inflammatory signaling pathways will be discussed.

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