Systemic Cytokine Release Research Articles

Modulation of urelumab glycosylation separates immune stimulatory activity from organ toxicity.

Checkpoint control and immunomodulatory antibodies have become important tools for modulating tumor or self-reactive immune responses. A major issue preventing to make full use of the potential of these immunomodulatory antibodies are the severe side-effects, ranging from systemic cytokine release syndrome to organ-specific toxicities. The IgG Fc-portion has been demonstrated to contribute to both, the desired as well as the undesired antibody activities of checkpoint control and immunomodulatory antibodies via binding to cellular Fcγ-receptors (FcγR). Thus, choosing IgG subclasses, such as human IgG4, with a low ability to interact with FcγRs has been identified as a potential strategy to limit FcγR or complement pathway dependent side-effects. However, even immunomodulatory antibodies on the human IgG4 background may interact with cellular FcγRs and show dose limiting toxicities. By using a humanized mouse model allowing to study the immunomodulatory activity of human checkpoint control antibodies in vivo, we demonstrate that deglycosylation of the CD137-specific IgG4 antibody urelumab results in an amelioration of liver toxicity, while maintaining T cell stimulatory activity. In addition, our results emphasize that antibody dosing impacts the separation of side-effects of urelumab from its therapeutic activity via IgG deglycosylation. Thus, glycoengineering of human IgG4 antibodies may be a possible approach to limit collateral damage by immunomodulatory antibodies and allow for a greater therapeutic window of opportunity.

Rapid generation of a mouse model for evaluating on-target normal tissue toxicity of human CAR-T cells using replication-defective recombinant adenovirus

IntroductionThe on-target off-tumor toxicity of chimeric antigen receptor-engineered T cells (CAR-T) might lead to fatal side effects in cancer patients, which remains as a major obstacle to the clinical application of CAR-T immunotherapy. The off-tumor on-target normal tissue toxicity of CAR-T cells needs to be evaluated in preclinical studies using rational animal models. ObjectivesWe aim to develop a rational animal model for assessing the off-tumor on-target normal tissue toxicity of various CAR-T cell designs quickly. MethodsWe used a recombinant adenovirus type 5 carrying human HER2/ERBB2 (Ad5-HER2) or CD47 gene (Ad5-CD47) to rapidly generate a mouse model with tunable human antigen expression on normal liver tissue to determine immunotoxicity of traditional CAR-T and hypoxia-response CAR-T cells in vivo. ResultsThe obvious liver damage and lymphocyte infiltration were not observed in mice with human antigen-high livers 8 days post-infection. Interestingly, the lethal liver damage, systemic cytokine release and CAR-T cells infiltration in liver were only observed in mice that received traditional CAR-T cells, but not in hypoxia-response CAR-T cells. ConclusionAdenovirus-based expression of target antigen in normal mouse tissue may be a useful method for assessing on-target CAR-T cell toxicity in normal tissues, especially various CAR-T cell designs that have the potency of conditional regulation in tumor microenvironment (TME).

Abstract 4240: In vivo assessment of AICD and cytokine release upon treatment of OKT3 and CD3 bispecific antibody in homozygous CD3EDG HuGEMM™

Abstract Introduction: CD3 bispecific antibodies have transformed the therapeutic landscape of immunotherapy for some hematological malignancies, however, the clinical therapeutic effects of CD3 bispecific therapies is still under investigation for solid tumors. Moreover, CD3 bispecific antibody-mediated tumor targeting as well as T cell engagement have resulted in cytokine release syndrome (CRS), increased on-target/off-tumor toxicities and poor T cell infiltration, which may affect safety and limit therapeutic efficacy. To better understand the relationship between T cell activation and systemic cytokine release in the context of CD3 bispecific antibody treatment, a homozygous human CD3EDG HuGEMM࣪ preclinical model was developed. Methods: The homozygous CD3EDG HuGEMM mice, which express human CD3ε/CD3δ/CD3γ on the surface of T cells, were subcutaneously inoculated with MC38 or MC38-hEpCAM HuCELL™ syngeneic tumors and treated with vehicle, anti-mPD-1 (RMP1-14), OKT3, and anti-hCD3×hEpCAM. For efficacy studies, mouse body weight and tumor volume were measured twice weekly and tumor growth inhibition (TGI%) was determined. To investigate OKT3 or CD3 bispecifics-induced cytokine release, mouse body weight was monitored daily and several inflammatory and proinflammatory cytokines in the serum were detected by MSD. Results: Firstly, anti-mPD-1 treatment (5 mg/kg and 15 mg/kg i.p.) of homozygous CD3EDG mice engrafted with MC38 syngeneic tumors led to 42% and 62% TGI, respectively. OKT3 treatment of MC38-hEpCAM bearing homozygous CD3EDG HuGEMM promoted tumor growth (TGI= -80%), likely due to activation-induced cell death (AICD) of T cells. In addition, CRS was induced within 24 hours of OKT3 dosing, with IL-2, IL-6, and TNF-α peaking 2 hr post the 1st dose, and IFN-γ, IL-10 and IL-5 peaking 6 hr post the 1st dose. In contrast, no significant cytokine release was observed upon anti-hCD3×hEpCAM treatment despite remarkable TGI, indicating that the delicate balance of in vivo T cell activation and T cell cytotoxicity is crucial for effective tumor killing by CD3 bispecific antibodies or engagers. Conclusions: Our CD3EDG HuGEMM and HuCELL models provide a predictive platform for in vivo efficacy and safety assessment of CD3 bispecific or trispecific antibodies. The uncoupling of systemic cytokine release and T cell cytotoxicity via CD3 bispecific or trispecific antibodies provides a biological rationale to clinically explore preventative treatment approaches to avoid or reduce CRS-related toxicity, as well as combination approaches to increase selectivity and efficacy. Citation Format: Daniel XF He. In vivo assessment of AICD and cytokine release upon treatment of OKT3 and CD3 bispecific antibody in homozygous CD3EDG HuGEMM™ [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4240.

Abstract 2906: AGEN1571 is a novel high-affinity ILT2 antagonist antibody that promotes adaptive and innate immune responses

Abstract Background: Ig-Like Transcript 2 (ILT2, LILRB1) is an inhibitory receptor prominently expressed on resting macrophages, monocytes, and dendritic cells (DCs), with variable expression on CD4+ T cells, CD8+ T cells, B cells, NK cells, and NKT cells in the tumor microenvironment. Interaction of ILT2 with its ligands, HLA-G and classical MHC class I molecules, is reported to impair cytotoxic activity of NK and effector T cells, attenuate B cell function, inhibit antigen-presentation by dendritic cells, and promote immunosuppressive activity of myeloid cells. Further, high ILT2 expression has been associated with poor prognosis in several human malignancies. As a result, ILT2 has been proposed as a therapeutic target to promote antitumor immunity and to overcome resistance to checkpoint blockade. Here, we report that AGEN1571, a fully human anti-ILT2 monoclonal IgG4κ antibody, reversed ILT2-mediated immunosuppression and promoted activation of NK, NKT, T cells, and myeloid cells in a series of preclinical studies. Methods: AGEN1571 binding to ILT2 was analyzed by SPR and flow cytometry. HDX-MS was used to identify the AGEN1571 binding epitope on ILT2. Mechanisms of AGEN1571-mediated modulation of immune cell function were evaluated using reporter cell lines and primary cell-based in vitro and ex vivo assays. Results: AGEN1571 bound to recombinant ILT2 with an approximate monovalent binding affinity of 0.38 nM and to cell-expressed ILT2 with an EC50 of 0.07 - 0.55 nM, depending on cell type and donor. AGEN1571 did not cross-react with related LILRA and LILRB family members except with weak reactivity to ILT4 (~370 nM). Consistent with its binding epitope, AGEN1571 potently blocked ILT2 binding to HLA-A, -B, -C, and -G and restored FcγR signaling inhibited by ILT2-HLA-G engagement in dose-dependent manner. AGEN1571 also augmented NFκB and ISRE activation induced by TLR, FcγR, and STING agonists in myeloid cells, and promoted polarization of primary human macrophages towards a pro-inflammatory phenotype. ILT2 blockade with AGEN1571 alone and in combination with a PD-1 antagonist enhanced secretion of pro-inflammatory cytokines and activation of NK, NKT and CD8+ T cells in a PBMC tumor cell co-culture assay. AGEN1571 was designed to have minimal binding to FcγR and complement which has been confirmed by lack of FcγR signaling and complement cascade induction in vitro. An in silico T cell epitope screen predicted AGEN1571 to be non-immunogenic, while AGEN1571 showed no evidence of inducing systemic cytokine release in a cytokine release assay using whole blood and PBMC cultures. Conclusion: AGEN1571 is a novel high-affinity ILT2 antagonist antibody that effectively antagonizes ILT2 to enhance T cell, NK cell, NKT cell, and myeloid activity. These data support clinical development of AGEN1571 as a therapeutic agent for patients with solid tumors. Citation Format: Olga Udartseva, Malgorzata Pupecka-Swider, Pilar Garcia-Broncano, Naxin Guo, Spencer Campbell, Elizabeth Klakus, Rebecca Ward, Priyadarshini Iyer, Christine Brittsan, Beth Wensley, Benjamin Morin, Andrew Slee, Dhan Chand, Claire Galand, Olga Ignatovich, Emmanuel Briend, David Savitsky. AGEN1571 is a novel high-affinity ILT2 antagonist antibody that promotes adaptive and innate immune responses [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2906.

Abstract 2888: Tumor-targeted CD28 bispecific POWERbody࣪ for safe and synergistic T cell-mediated immunotherapy

Abstract Targeting CD28 for systemic T cell activation caused severe cytokine storm and multiorgan failure in an anti-CD28 antibody TGN1412 phase 1 trial. However, tumor specific CD28 targeting in a tumor associated antigen (TAA)×CD28 bispecific format, similar to the clinically validated tumor specific CD3 bispecific T-cell engagers (TCEs), offers an attractive solution to mitigate the serious safety concerns associated with systemic CD28 activation while delivering potent T-cell costimulatory signal. Our goal is to combine tumor specific bispecific TCEs targeting both CD3 and CD28, the two essential pathways in T cell activation for safe and long-lasting T cell-mediated synergistic immunotherapies. Following our success in utilizing the CD3 POWERbody™ TCE platform for tumor targeting with tight safety control, we further applied our suite of antibody technologies to develop tumor specific bispecific CD28 POWERbody TCE programs. Our NEObody™ and SAFEbody® technologies enabled us to discover and engineer species cross-reactive anti-CD28 antibodies targeting a unique and conserved epitope of CD28 as well as precision masking of the antigen binding sites for conditional activation in tumor microenvironment. The engineered tailor-made anti-CD28 arm and the tumor specific antigen targeting arm were then integrated into our proprietary bispecific platform that has robust CMC properties. Toward this end we developed multiple TAA×CD28 bispecific TCEs, including B7-H3×CD28, HER2×CD28, and TROP-2×CD28, etc., which possess fine-tuned specificity and safety profiles to minimize their on-target off-tumor toxicities and to prevent the systemic cytokine release syndrome (CRS). These TAA×CD28 bispecific POWERbodies have no superagonist activities on their own and can be activated for tumor antigen binding by the TAA arm and T cell engagement by the CD28 arm. When combined with TAA×CD3 TCEs and/or checkpoint inhibitors, they show strong synergistic T cell-mediated antitumor responses with robust safety profiles. Taken together, our tumor specific CD28 bispecific POWERbody TCEs exhibit enormous potential to fulfill the promises of safe and durable T cell-mediated immunotherapies when combined with CD3 bispecific POWERbody TCEs and/or checkpoint inhibitors. Citation Format: Guizhong Liu, Zhengxi Dai, Jiagui Qu, Jianfeng Shi, Qi Zhao, Bin Cai, Aaron N. Nguyen, Songmao Zheng, Jiangchun Xu, Yan Li, Felix Du, Peter Luo. Tumor-targeted CD28 bispecific POWERbody࣪ for safe and synergistic T cell-mediated immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2888.

Abstract 2869: ADG138, a novel HER2×CD3 POWERbody™ integrating bispecific TCE with precision masking to control cytokine release syndrome and on-target off-tumor toxicity for single agent and combination therapies in HER2-expressing solid tumors

Abstract Bispecific T-cell engagers (TCEs) have shown therapeutic promise in treating hematologic cancers. However, their utility in treating solid tumors has yet to be effectively demonstrated due to on-target off-tumor toxicity and systemic cytokine release syndrome (CRS). To explore the full potential of TCEs as a powerful modality of immunotherapy for solid tumors, we developed ADG138, a novel HER2×CD3 POWERbody™ TCE by applying our SAFEbody® precision masking technology to double mask the binding interfaces in both ADG138 arms using covalently linked designer peptides in order to limit on-target off-tumor toxicities in normal tissues and to avert systemic CRS. In the tumor microenvironment (TME), the double masked ADG138 prodrug can be activated for concomitant in situ binding to the targeted cancer cells by the HER2 arm and to T cells by the CD3 arm to selectively enhance T cell responses against tumor cells specifically. Nonclinical studies demonstrated that when activated, ADG138 was highly potent in inducing T cell mediated cytotoxicity of both high and low HER2-expressing tumor cells in vitro, whereas in its double masked prodrug form ADG138 exhibited high masking efficiency with greatly reduced HER2 binding, T cell activation, and T cell mediated cytotoxicity. In in vivo human PBMC-engrafted tumor xenograft models, ADG138 induced robust tumor regression of both high and low HER2-expressing tumors in mice. Furthermore, combination of ADG138 with our species cross-reactive immuno-oncology therapeutics mediated strong synergistic antitumor activities in HER2 positive syngeneic solid tumor models in human CD3e knock-in mice. The double masked ADG138 prodrug also exhibited excellent safety profiles and normal pharmacokinetics in exploratory toxicology studies in cynomolgus monkeys, achieving over a 300-fold higher tolerated dose in striking contrast with its parental TCE that lacks masking. These nonclinical studies demonstrated that ADG138, a novel double masked HER2×CD3 POWERbody TCE, exhibited an impressively high therapeutic index relative to its parental non-masked TCE in HER2 high and low expressing solid tumors. This provides strong support for advancing the ADG138 prodrug into clinical development for treating HER2-expressing solid tumors as a single agent and in combination with other immune stimulatory agents. Citation Format: Guizhong Liu, Yan Li, Zhengxi Dai, Jiagui Qu, Jianfeng Shi, Qi Zhao, Linhai Qu, Aaron N. Nguyen, Songmao Zheng, Jiangchun Xu, Felix Du, Peter Luo. ADG138, a novel HER2×CD3 POWERbody™ integrating bispecific TCE with precision masking to control cytokine release syndrome and on-target off-tumor toxicity for single agent and combination therapies in HER2-expressing solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2869.

Phase 1 dose escalation study of DSP107, a first-in-class CD47 and 4-1BB targeting multifunctional immune-recruitment protein, in patients with advanced solid tumors.

2647 Background: DSP107 is a bi-functional, trimeric, fusion protein composed of sequences from the extracellular domain of SIRPα and 4-1BBL. The SIRPα arm targets CD47 overexpressed on tumor cells, blocking the “don’t eat me” checkpoint and triggering tumor cell phagocytosis. The trimeric 4-1BBL arm, once cross-presented and immobilized by SIRPα binding to CD47, interacts with 4-1BB expressed on activated immune cells, mainly T- and NK cells in the tumor microenvironment, and stimulates their proliferation and activation. Thereby, DSP107 triggers both an innate and an adaptive immune response. Here we describe data from the completed DSP107 monotherapy dose escalation portion of study NCT04440735. Methods: Adult patients with advanced solid tumors were treated with weekly intravenous DSP107 infusions (0.01 - 10 mg/kg) during 3-week treatment cycles. An accelerated dose escalation in single patient cohorts (dose levels 1-3) was followed by a standard 3 + 3 design. The primary objective was to determine safety, tolerability and pharmacokinetic (PK) parameters. Paired biopsies were obtained from 8 patients (screening, after cycle 2). Restaging imaging was performed every two months and evaluated by RECIST criteria. Results: In 23 patients, DSP107 demonstrated no treatment related hematologic or hepatic adverse events (AEs) and no dose limiting toxicities. Grade 1-2 treatment related AEs were observed in 70% of patients (16/23). The most frequent AEs included infusion related reaction (IRR; 26%), diarrhea (17%), fatigue (17%), nausea (13%) and constipation (9%). IRRs were managed during subsequent infusions by reducing the infusion rate and administering IV fluids. No significant systemic cytokine release was measured at any dose level using a 10-plex, pro-inflammatory panel. PK analysis revealed 100% CD47 receptor engagement on peripheral T and NK cells at doses of 3 mg/kg and above. DSP107 did not bind CD47 on red blood cells at any dose. Preliminary histologic assessment of paired biopsies by an independent, blinded pathologist demonstrated increased tumor necrosis compared to screening in 3 out of 4 patients associated with immune cell infiltration. Immuno-profiling of tumor by immunofluorescence is on-going. Stable disease as best response was observed in 11/22 patients with treatment duration up to 26 weeks. Conclusions: DSP107 is a novel, CD47 and 4-1BB targeting fusion protein with a differentiated safety, binding and pharmacodynamic profile compared to other CD47 and 4-1BB targeting agents. Clinical trial information: NCT04440735.

Cytokine Responses to Adenovirus and Adenovirus Vectors

The expression of cytokines and chemokines in response to adenovirus infection is tightly regulated by the innate immune system. Cytokine-mediated toxicity and cytokine storm are known clinical phenomena observed following naturally disseminated adenovirus infection in immunocompromised hosts as well as when extremely high doses of adenovirus vectors are injected intravenously. This dose-dependent, cytokine-mediated toxicity compromises the safety of adenovirus-based vectors and represents a critical problem, limiting their utility for gene therapy applications and the therapy of disseminated cancer, where intravenous injection of adenovirus vectors may provide therapeutic benefits. The mechanisms triggering severe cytokine response are not sufficiently understood, prompting efforts to further investigate this phenomenon, especially in clinically relevant settings. In this review, we summarize the current knowledge on cytokine and chemokine activation in response to adenovirus- and adenovirus-based vectors and discuss the underlying mechanisms that may trigger acute cytokine storm syndrome. First, we review profiles of cytokines and chemokines that are activated in response to adenovirus infection initiated via different routes. Second, we discuss the molecular mechanisms that lead to cytokine and chemokine transcriptional activation. We further highlight how immune cell types in different organs contribute to synthesis and systemic release of cytokines and chemokines in response to adenovirus sensing. Finally, we review host factors that can limit cytokine and chemokine expression and discuss currently available and potential future interventional approaches that allow for the mitigation of the severity of the cytokine storm syndrome. Effective cytokine-targeted interventional approaches may improve the safety of systemic adenovirus delivery and thus broaden the potential clinical utility of adenovirus-based therapeutic vectors.

Carvedilol targets \u03b2-arrestins to rewire innate immunity and improve oncolytic adenoviral therapy

Oncolytic viruses are being tested in clinical trials, including in women with ovarian cancer. We use a drug-repurposing approach to identify existing drugs that enhance the activity of oncolytic adenoviruses. This reveals that carvedilol, a β-arrestin-biased β-blocker, synergises with both wild-type adenovirus and the E1A-CR2-deleted oncolytic adenovirus, dl922-947. Synergy is not due to β-adrenergic blockade but is dependent on β-arrestins and is reversed by β-arrestin CRISPR gene editing. Co-treatment with dl922-947 and carvedilol causes increased viral DNA replication, greater viral protein expression and higher titres of infectious viral particles. Carvedilol also enhances viral efficacy in orthotopic, intraperitoneal murine models, achieving more rapid tumour clearance than virus alone. Increased anti-cancer activity is associated with an intratumoural inflammatory cell infiltrate and systemic cytokine release. In summary, carvedilol augments the activity of oncolytic adenoviruses via β-arrestins to re-wire cytokine networks and innate immunity and could therefore improve oncolytic viruses for cancer patient treatment.

Molecular and cellular mechanisms of itch and pain in atopic dermatitis and implications for novel therapeutics.

Atopic dermatitis is a chronic inflammatory skin disease. Patients with atopic dermatitis experience inflammatory lesions associated with intense itch and pain, which lead to sleep disturbance and poor mental health and quality of life. We review the molecular mechanisms underlying itch and pain symptoms in atopic dermatitis and discuss the current clinical development of treatments for moderate‐to‐severe atopic dermatitis. The molecular pathology of atopic dermatitis includes aberrant immune activation involving significant cross‐talk among the skin and immune and neuronal cells. Exogenous and endogenous triggers modulate stimulation of mediators including cytokine/chemokine expression/release by the skin and immune cells, which causes inflammation, skin barrier disruption, activation and growth of sensory neurons, itch and pain. These complex interactions among cell types are mediated primarily by cytokines, but also involve chemokines, neurotransmitters, lipids, proteases, antimicrobial peptides, agonists of ion channels or various G protein–coupled receptors. Patients with atopic dermatitis have a cytokine profile characterised by abnormal levels of interleukins 4, 12, 13, 18, 22, 31 and 33; thymic stromal lymphopoietin; and interferon gamma. Cytokine receptors mainly signal through the Janus kinase/signal transducer and activator of transcription pathway. Among emerging novel therapeutics, several Janus kinase inhibitors are being developed for topical or systemic treatment of moderate‐to‐severe atopic dermatitis because of their potential to modulate cytokine expression and release. Janus kinase inhibitors lead to changes in gene expression that have favourable effects on local and systemic cytokine release, and probably other mediators, thus successfully modulating molecular mechanisms responsible for itch and pain in atopic dermatitis.

Magnetic nanocluster-mediated photothermal effect and macrophage modulation for synergistic photothermal immunotherapy of cancer.

In the tumor microenvironment, macrophages predominately exhibit M2-type functionalities which promote malignant progression and cancer metastasis, thus posing a big hurdle for current anticancer strategies. Different approaches have been exploited to reverse the macrophages towards the M1 pro-inflammatory phenotype; however, it is hard to achieve tumor regression with this macrophage modulation alone. Herein we synthesized photothermal magnetic nanoclusters (MNCs) to test their capability for reprograming M2 macrophages towards the M1 phenotype. We demonstrated that these photothermal MNCs themselves can effectively trigger this desired macrophage repolarization, increase the phagocytosis of macrophages at the tumor site, and cause subsequent T cell activation with enhanced systemic cytokine release, leading to cancer cell killing both in vitro and in vivo. More interestingly, it was found that the photothermal effect can further facilitate this immune activation to a greater extent, inducing much higher level of macrophage repolarization and T cell infiltration into the tumor site as well as eliciting a much more efficient antitumor effect compared with MNCs alone. Our findings demonstrate that MNCs combined with their photothermal effect can reverse the local suppressive environment of the tumor by macrophage and T cell modulation, providing an effective approach to trigger systemic immune responses that contribute to an enhanced overall anticancer outcome and the suppression of cancer metastasis.

Brain capillary obstruction during neurotoxicity in a mouse model of anti-CD19 chimeric antigen receptor T-cell therapy.

Immunotherapy for haematologic malignancies with CD19-directed chimeric antigen receptor T cells has been highly successful at eradicating cancer but is associated with acute neurotoxicity in ∼40% of patients. This neurotoxicity correlates with systemic cytokine release syndrome, endothelial activation and disruption of endothelial integrity, but it remains unclear how these mechanisms interact and how they lead to neurologic dysfunction. We hypothesized that dysfunction of the neurovascular unit is a key step in the development of neurotoxicity. To recapitulate the interaction of the intact immune system with the blood–brain barrier, we first developed an immunocompetent mouse model of chimeric antigen receptor T-cell treatment-associated neurotoxicity. We treated wild-type mice with cyclophosphamide lymphodepletion followed by escalating doses of murine CD19-directed chimeric antigen receptor T cells. Within 3–5 days after chimeric antigen receptor T-cell infusion, these mice developed systemic cytokine release and abnormal behaviour as measured by daily neurologic screening exams and open-field testing. Histologic examination revealed widespread brain haemorrhages, diffuse extravascular immunoglobulin deposition, loss of capillary pericyte coverage and increased prevalence of string capillaries. To measure any associated changes in cerebral microvascular blood flow, we performed in vivo two-photon imaging through thinned-skull cranial windows. Unexpectedly, we found that 11.9% of cortical capillaries were plugged by Day 6 after chimeric antigen receptor T-cell treatment, compared to 1.1% in controls treated with mock transduced T cells. The capillary plugs comprised CD45+ leucocytes, a subset of which were CD3+ T cells. Plugging of this severity is expected to compromise cerebral perfusion. Indeed, we found widely distributed patchy hypoxia by hypoxyprobe immunolabelling. Increased serum levels of soluble ICAM-1 and VCAM-1 support a putative mechanism of increased leucocyte–endothelial adhesion. These data reveal that brain capillary obstruction may cause sufficient microvascular compromise to explain the clinical phenotype of chimeric antigen receptor T-cell neurotoxicity. The translational impact of this finding is strengthened by the fact that our mouse model closely approximates the kinetics and histologic findings of the chimeric antigen receptor T-cell neurotoxicity syndrome seen in human patients. This new link between systemic immune activation and neurovascular unit injury may be amenable to therapeutic intervention.

Emergence of an adaptive immune paradigm to explain celiac disease: a perspective on new evidence and implications for future interventions and diagnosis

ABSTRACT Introduction Recent patient studies have shown that gluten-free diet is less effective in treating celiac disease than previously believed, and additionally patients remain vulnerable to gluten-induced acute symptoms and systemic cytokine release. Safe and effective pharmacological adjuncts to gluten-free diet are in preclinical and clinical development. Clear understanding of the pathogenesis of celiac disease is critical for drug target identification, establishing efficacy endpoints and to develop noninvasive biomarkers suitable to monitor and potentially diagnose celiac disease. Areas covered The role and clinical effects of CD4+ T cells directed against deamidated gluten in the context of an ‘adaptive immune paradigm’ are reviewed. Alternative hypotheses of gluten toxicity are discussed and contrasted. In the context of recent patient studies, implications of the adaptive immune paradigm for future strategies to prevent, diagnose, and treat celiac disease are outlined. Expert Opinion Effective therapeutics for celiac disease are likely to be approved and necessitate a variety of new clinical instruments and tests to stratify patient need, monitor remission, and confirm diagnosis in uncertain cases. Sensitive assessments of CD4+ T cells specific for deamidated gluten are likely to play a central role in clinical management, and to facilitate research and pharmaceutical development.

Real-World Treatment Patterns and Outcomes in Patients with Hemophagocytic Lymphohistiocytosis (HLH) and Other Clinical Conditions Treated with Emapalumab: The Real-HLH Study Design

Introduction: Hemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening hyperinflammatory syndrome characterized by overactivation of the immune system due to systemic release of proinflammatory cytokines, especially of interferon gamma (IFNγ), and persistent activation of macrophages/histiocytes and T cells. Emapalumab, a fully human, anti-IFNγ monoclonal antibody that binds to both free and receptor-bound IFNy, neutralizing its biologic activity, was approved by the Food and Drug Administration (FDA) in 2018 for the treatment of adult and pediatric patients with primary HLH with refractory, recurrent or progressive disease or intolerance with conventional HLH therapy. The safety and efficacy of emapalumab was based on results from a pivotal phase 2/3 trial which reported a 63% overall response in patients treated with emapalumab. Since approval, no study has evaluated the use of emapalumab in a larger cohort of patients in the real-world clinical setting.Aim: To assess real-world treatment patterns and outcomes, clinical and demographic characteristics among patients treated with emapalumab.Method: This retrospective, non-interventional, observational medical chart review study will include patients treated across treatment centers in the US with emapalumab in a non-clinical trial setting. The study aims to include more than 100 patients who have been treated with at least one dose of emapalumab between November 20, 2018 and December 31, 2020 (patient identification period). The date that the patient initiates treatment with emapalumab within the patient identification period is defined as the index date. The post-index date is defined as the period from the index date through to the study end date (June 30, 2021), end of data availability for the patient, or date of death, whichever occurs first. Patients will be classified into three groups (i.e. primary HLH, secondary HLH, or non-HLH) based on the information obtained from their charts, the HLH 2004 diagnostic criteria, and adjudication by the REAL-HLH Steering Committee.Results: The primary objective of the study is to describe treatment patterns in patients with HLH treated with emapalumab in a real-world clinical setting, including emapalumab dose, treatment duration, and reasons for initiating or discontinuing treatment. The secondary objectives are to describe demographic and clinical characteristics of patients with HLH treated with emapalumab, and their outcomes. The exploratory objectives include detailing the demographic, clinical characteristics, treatment patterns, and outcomes of patients with non-HLH clinical conditions treated with emapalumab (Table 1). Demographics and clinical characteristics will be analyzed at the time of diagnosis. Treatment patterns and outcomes will be analyzed during the post-index date.Conclusion: The study aims to assess treatment patterns and outcomes, clinical and demographic characteristics among patients treated with emapalumab, a novel IFNγ blocking agent, in real-world clinical settings in the US. [Display omitted] DisclosuresAllen: Sobi: Consultancy. Leiding: Sobi: Consultancy. Chandrakasan: Sobi: Consultancy. Walkovich: X4 Pharmaceuticals: Other: Local PI for clinical trial involving mavorixafor and patients with neutropenia; Swedish Orphan Biovitrum AB (Sobi): Consultancy, Honoraria; Pharming: Honoraria, Membership on an entity's Board of Directors or advisory committees; Horizon Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees. Oladapo: Sobi: Current Employment. Yee: Sobi: Current Employment. Pednekar: Sobi: Consultancy; PRECISIONheor: Current Employment. Raza: Sobi: Consultancy; PRECISIONheor: Current Employment. Jordan: Sobi: Consultancy.

AML Cell Vaccines Co-Expressing CD80 and IL-15/IL-15 Receptor Alpha Induce Activation and Cytolytic Activity in Post Remission Autologous Patient PBMC Ex Vivo

There is a critical need for more effective therapy for acute myelogenous leukemia (AML). Although many patients achieve remission, most relapse with poor outcomes. Even after allogeneic Stem Cell Transplantation (SCT), 30-50% of patients relapse due to the persistence of residual disease.To address the poor immunogenicity of AML cells and the diminished immune responsiveness of patients, our candidate autologous AML vaccine is lentivirally engineered, in each patient's leukemic cells, to express CD80, IL-15, and IL-15 Receptor alpha (IL-15Rα). In prior studies in a syngeneic 32Dp210 murine AML model, CD80-mediated co-stimulation of T-cells combined with immune activation by the IL-15/IL-15Rα heterodimer showed unprecedented synergy in induction of anti-leukemic cytolytic activity (Shi, Y. et al, 2018). This was observed in both ex vivo co-culture and in vivo where vaccinated leukemic mice had >80% cure rates. No local skin, organ, or systemic toxicity was observed, nor was there evidence of systemic cytokine release of IL-6 or TNFα after SC or IV injection of up to 10 8 transduced irradiated AML cells.We confirmed the feasibility of producing patient-derived AML vaccines by transduction of 16 independent AML samples with a tri-cistronic lentiviral vector (TLV) that contains human CD80, IL-15 and IL-15Rα. Transduction levels were 11-71% of cells (median 38.6%).To define the minimum transduction level required for PBMC activation and to assess synergy of co-expressed human CD80, IL-15, and IL-15Rα, allogenic U937 leukemia cells were initially used as stimulators. Transduced U937 (U937-TLV) had high-level surface expression of CD80 and IL-15, secreted IL-15 (7 ng/ml/24 hours from 2 x 10 6 cells/ml) and activated CD3+ T-cells from an AML patient (Fig.1). Mixtures of irradiated U937-TLV with non-transduced U937 were created at fixed ratios (100%, 80%, 40%, 20%, 10%, 5%, 0%) for overnight co-culture with patient PBMC. At 24 hours, the T-cells were analyzed for activation by measurement of the frequency of CD69+ CD4 or CD8 T cells (Fig. 1), normalized to expression of unstimulated PBMC (0%) and the percentage of maximal CD69 expression with 100% U937-TLV (100%). Background levels of activation due to the presence of allogenic U937 were negligible. Co-culture with as little as 10% transduced U937-TLV reliably activated patient T-cells. To assess the synergy of CD80, IL-15 and IL-15Rα expression, parallel experiments were performed with PBMC co-cultured in IL-15 containing supernatants from U937-TLV cells (Fig. 1). The frequencies of activated T-cells were significantly higher after co-culture with U937/U937-TLV cells than after stimulation with IL-15-containing supernatants from similar ratios of U937/U937-TLV, confirming the synergy of CD80 and IL-15/IL-15Rα in the transduced cells.To better, model the clinical setting, we assessed induction of immune responses of patient T cells to autologous transduced AML. PBMC were stimulated with transduced or non-transduced autologous AML cells vs stimulation with allogeneic U937-TLV, or with anti-CD3/CD28 beads to define maximal stimulation. Negative controls included culture of PBMC alone. All patients had T-cell activation, as measured by induction of CD69, HLA-DR and CD95 (Fas) expression, although there was heterogeneity in the nature of responses, e.g., disparate induction of the markers in individual patients (Fig. 2A and B). Induction of cytotoxic effector pathways was confirmed by detection of CD178 (FasL) and perforin expression (Figure 2C and D). Overall, all patients' PBMC had the capacity to mount T-cell responses of similar magnitude to both allogeneic U937-TLV and autologous vaccine.These studies establish that autologous AML cells transduced with CD80, IL-15 and IL-15Rα can elicit specific anti-leukemic T-cell responses, even in the face of prior lymphodepleting chemotherapy. A strength of this autologous vaccine strategy is that it is agnostic to which AML proteins are immunogenic for each patient. Although uniformly detected, there was heterogeneity in the induction of activation markers and effector pathways, which may reflect host and/or disease-related differences. The mechanisms underlying differences in the nature of responses in patients will be important to understand and will provide the basis for future immune correlative studies for our Phase 1 vaccine trial in transplant ineligible AML patients. [Display omitted] DisclosuresKohn: Lyrik Therapeutics: Membership on an entity's Board of Directors or advisory committees; MyoGene Bio: Membership on an entity's Board of Directors or advisory committees; ImmunoVec: Membership on an entity's Board of Directors or advisory committees; Pluto Immunotherapeutics: Membership on an entity's Board of Directors or advisory committees; Allogene: Membership on an entity's Board of Directors or advisory committees; UC Regents: Patents & Royalties; Bluebird Bio: Membership on an entity's Board of Directors or advisory committees; Sangamo Biosciences: Membership on an entity's Board of Directors or advisory committees.

Effect of anti-interleukin drugs in patients with COVID-19 and signs of cytokine release syndrome (COV-AID): a factorial, randomised, controlled trial

BackgroundInfections with SARS-CoV-2 continue to cause significant morbidity and mortality. Interleukin (IL)-1 and IL-6 blockade have been proposed as therapeutic strategies in COVID-19, but study outcomes have been conflicting. We sought to study whether blockade of the IL-6 or IL-1 pathway shortened the time to clinical improvement in patients with COVID-19, hypoxic respiratory failure, and signs of systemic cytokine release syndrome.MethodsWe did a prospective, multicentre, open-label, randomised, controlled trial, in hospitalised patients with COVID-19, hypoxia, and signs of a cytokine release syndrome across 16 hospitals in Belgium. Eligible patients had a proven diagnosis of COVID-19 with symptoms between 6 and 16 days, a ratio of the partial pressure of oxygen to the fraction of inspired oxygen (PaO2:FiO2) of less than 350 mm Hg on room air or less than 280 mm Hg on supplemental oxygen, and signs of a cytokine release syndrome in their serum (either a single ferritin measurement of more than 2000 μg/L and immediately requiring high flow oxygen or mechanical ventilation, or a ferritin concentration of more than 1000 μg/L, which had been increasing over the previous 24 h, or lymphopenia below 800/mL with two of the following criteria: an increasing ferritin concentration of more than 700 μg/L, an increasing lactate dehydrogenase concentration of more than 300 international units per L, an increasing C-reactive protein concentration of more than 70 mg/L, or an increasing D-dimers concentration of more than 1000 ng/mL). The COV-AID trial has a 2 × 2 factorial design to evaluate IL-1 blockade versus no IL-1 blockade and IL-6 blockade versus no IL-6 blockade. Patients were randomly assigned by means of permuted block randomisation with varying block size and stratification by centre. In a first randomisation, patients were assigned to receive subcutaneous anakinra once daily (100 mg) for 28 days or until discharge, or to receive no IL-1 blockade (1:2). In a second randomisation step, patients were allocated to receive a single dose of siltuximab (11 mg/kg) intravenously, or a single dose of tocilizumab (8 mg/kg) intravenously, or to receive no IL-6 blockade (1:1:1). The primary outcome was the time to clinical improvement, defined as time from randomisation to an increase of at least two points on a 6-category ordinal scale or to discharge from hospital alive. The primary and supportive efficacy endpoints were assessed in the intention-to-treat population. Safety was assessed in the safety population. This study is registered online with ClinicalTrials.gov (NCT04330638) and EudraCT (2020-001500-41) and is complete.FindingsBetween April 4, and Dec 6, 2020, 342 patients were randomly assigned to IL-1 blockade (n=112) or no IL-1 blockade (n=230) and simultaneously randomly assigned to IL-6 blockade (n=227; 114 for tocilizumab and 113 for siltuximab) or no IL-6 blockade (n=115). Most patients were male (265 [77%] of 342), median age was 65 years (IQR 54–73), and median Systematic Organ Failure Assessment (SOFA) score at randomisation was 3 (2–4). All 342 patients were included in the primary intention-to-treat analysis. The estimated median time to clinical improvement was 12 days (95% CI 10–16) in the IL-1 blockade group versus 12 days (10–15) in the no IL-1 blockade group (hazard ratio [HR] 0·94 [95% CI 0·73–1·21]). For the IL-6 blockade group, the estimated median time to clinical improvement was 11 days (95% CI 10–16) versus 12 days (11–16) in the no IL-6 blockade group (HR 1·00 [0·78–1·29]). 55 patients died during the study, but no evidence for differences in mortality between treatment groups was found. The incidence of serious adverse events and serious infections was similar across study groups.InterpretationDrugs targeting IL-1 or IL-6 did not shorten the time to clinical improvement in this sample of patients with COVID-19, hypoxic respiratory failure, low SOFA score, and low baseline mortality risk.FundingBelgian Health Care Knowledge Center and VIB Grand Challenges program.

Phase 1 open-label trial of intravenous administration of MVA-BN-brachyury-TRICOM vaccine in patients with advanced cancer

BackgroundMVA-BN-brachyury-TRICOM is a recombinant vector-based therapeutic cancer vaccine designed to induce an immune response against brachyury. Brachyury, a transcription factor overexpressed in advanced cancers, has been associated with treatment resistance,...

TNF blockade uncouples toxicity from antitumor efficacy induced with CD40 chemoimmunotherapy.

Agonist CD40 antibodies are under clinical development in combination with chemotherapy as an approach to prime for antitumor T cell immunity. However, treatment with anti-CD40 is commonly accompanied by both systemic cytokine release and liver transaminase elevations, which together account for the most common dose-limiting toxicities. Moreover, anti-CD40 treatment increases the potential for chemotherapy-induced hepatotoxicity. Here, we report a mechanistic link between cytokine release and hepatotoxicity induced by anti-CD40 when combined with chemotherapy and show that toxicity can be suppressed without impairing therapeutic efficacy. We demonstrate in mice and humans that anti-CD40 triggers transient hepatotoxicity marked by increased serum transaminase levels. In doing so, anti-CD40 sensitizes the liver to drug-induced toxicity. Unexpectedly, this biology is not blocked by the depletion of multiple myeloid cell subsets, including macrophages, inflammatory monocytes, and granulocytes. Transcriptional profiling of the liver after anti-CD40 revealed activation of multiple cytokine pathways including TNF and IL-6. Neutralization of TNF, but not IL-6, prevented sensitization of the liver to hepatotoxicity induced with anti-CD40 in combination with chemotherapy without impacting antitumor efficacy. Our findings reveal a clinically feasible approach to mitigate toxicity without impairing efficacy in the use of agonist CD40 antibodies for cancer immunotherapy.

Problems of Pathogenesis and Pathogenetic Therapy of COVID-19 from the Perspective of the General Theory of Pathological Systems (General Pathological Processes)

The COVID-19 pandemic examines not only the state of actual health care but also the state of fundamental medicine in various countries. Pro-inflammatory processes extend far beyond the classical concepts of inflammation. They manifest themselves in a variety of ways, beginning with extreme physiology, then allostasis at low-grade inflammation, and finally the shockogenic phenomenon of “inflammatory systemic microcirculation”. The pathogenetic core of critical situations, including COVID-19, is this phenomenon. Microcirculatory abnormalities, on the other hand, lie at the heart of a specific type of general pathological process known as systemic inflammation (SI). Systemic inflammatory response, cytokine release, cytokine storm, and thrombo-inflammatory syndrome are all terms that refer to different aspects of SI. As a result, the metabolic syndrome model does not adequately reflect the pathophysiology of persistent low-grade systemic inflammation (ChSLGI). Diseases associated with ChSLGI, on the other hand, are risk factors for a severe COVID-19 course. The review examines the role of hypoxia, metabolic dysfunction, scavenger receptors, and pattern-recognition receptors, as well as the processes of the hemophagocytic syndrome, in the systemic alteration and development of SI in COVID-19.

Autologous Placenta-derived Mesenchymal Stem Cell Transplantation for Labored Pregnant Patients With COVID-19

Coronavirus Disease 2019 (COVID-19) is one of the most critical health issues in the world. According to the findings, systemic proinflammatory cytokine release is associated with the pathogenesis of cytokine storm, contributing to morbidities and even mortality in patients diagnosed with COVID-19. Among pregnant patients diagnosed with COVID-19, preterm labor is one of the most crucial side effects, with a prevalence of up to 63.8% in some studies. As well as cytokine storm, proinflammatory cytokines are involved in preterm labor. Mesenchymal Stem Cells (MSCs) transplantation has been used in different trials to suppress inflammation in many inflammatory diseases. MSCs have also been successfully applied to treat patients diagnosed with COVID-19, considering the cytokine storm in these patients. So, it is possible to use the transplantation of MSCs derived from the maternal side of the placenta as an autologous product to suppress cytokine storm in critically ill patients diagnosed with COVID-19. The autologous transplantation of MSCs helps to suppress cytokine storm and systemic inflammation. Inhibition of systemic cytokine release could prevent poor outcomes, especially mortality and morbidities in the mentioned patients.