The Contribution of Liver Sinusoidal Endothelial Cells to Clearance of Therapeutic Antibody

Research Progress on the Immune Function of Liver Sinusoidal Endothelial Cells in Sepsis

Sepsis is a complex clinical syndrome closely associated with the occurrence of acute organ dysfunction and is often characterized by high mortality. Due to the rapid progression of sepsis, early diagnosis and intervention are crucial. Recent research has focused on exploring the pathological response involved in the process of sepsis. Liver sinusoidal endothelial cells (LSECs) are a special type of endothelial cell and an important component of liver non-parenchymal cells. Unlike general endothelial cells, which mainly provide a barrier function within the body, LSECs also have important functions in the clearance and regulation of the immune response. LSECs are not only vital antigen-presenting cells (APCs) in the immune system but also play a significant role in the development of infectious diseases and tumors through their specific immune regulatory pathways. However, in certain disease states, the functions of LSECs may be impaired, leading to immune imbalance and the development of organ failure. Investigating the immune pathways of LSECs in sepsis may provide new solutions for the prevention and treatment of sepsis and is crucial for maintaining microcirculation and improving patient outcomes.

Rat as a Predictive Model for Human Clearance and Bioavailability of Monoclonal Antibodies

BACKGROUND

The prediction of human clearance (CL) and subcutaneous (SC) bioavailability is a critical aspect of monoclonal antibody (mAb) selection for clinical development. While monkeys are a well-accepted model for predicting human CL, other preclinical species have been less-thoroughly explored. Unlike CL, predicting the bioavailability of SC administered mAbs in humans remains challenging as contributing factors are not well understood, and preclinical models have not been systematically evaluated.

METHODS

Non-clinical and clinical pharmacokinetic (PK) parameters were mined from public and internal sources for rats, cynomolgus monkeys, and humans. Intravenous (IV) and SC PK was determined in Sprague Dawley rats for fourteen mAbs without existing PK data. Together, we obtained cross-species data for 25 mAbs to evaluate CL and SC bioavailability relationships among rats, monkeys, and humans.

RESULTS

Rat and monkey CL significantly correlated with human CL and supported the use of species-specific exponents for body-weight-based allometric scaling. Notably, rat SC bioavailability significantly correlated with human SC bioavailability, while monkey SC bioavailability did not. Bioavailability also correlated with clearance.

CONCLUSIONS

The rat model enables an early assessment of mAb PK properties, allowing discrimination among molecules in the discovery pipeline and prediction of human PK. Importantly, rat SC bioavailability significantly correlated with human SC bioavailability, which has not been observed with other species. Rats are cost-effective and efficient relative to monkeys and provide a valuable tool for pharmacokinetic predictions in therapeutic antibody discovery.

Antibody-drug conjugate adverse effects can be understood and addressed based on immune complex clearance mechanisms

ABSTRACT

Numerous antibody-drug conjugates (ADCs) are being developed for cancer immunotherapy. Although several of these agents have demonstrated considerable clinical efficacy and have won Food and Drug Administration (FDA) approval, in many instances, they have been characterized by adverse side effects (ASEs), which can be quite severe in a fraction of treated patients. The key hypothesis in this perspective is that many of the most serious ASEs associated with the use of ADCs in the treatment of cancer can be most readily explained and understood due to the inappropriate processing of these ADCs via pathways normally followed for immune complex clearance, which include phagocytosis and trogocytosis. We review the key published basic science experiments and clinical observations that support this idea. We propose that it is the interaction of the ADC with Fcγ receptors expressed on off-target cells and tissues that can most readily explain ADC-mediated pathologies, which therefore provides a rationale for the design of protocols to minimize ASEs. We describe measurements that should help identify those patients most likely to experience ASE due to ADC, and we propose readily available treatments as well as therapies under development for other indications that should substantially reduce ASE associated with ADC. Our focus will be on the following FDA-approved ADC for which there are substantial literatures: gemtuzumab ozogamicin and inotuzumab ozogamicin; and trastuzumab emtansine and trastuzumab deruxtecan.

Progress in the study of antibody-drug conjugates for the treatment of cervical cancer

Cervical cancer is the second most prevalent malignancy affecting women's health globally, and the number of morbidity and mortality from cervical cancer continues to rise worldwide. The 5-year survival rate of patients with recurrent or metastatic cervical cancer is significantly reduced, and existing treatment modalities have low efficacy and high adverse effects, so there is a strong need for new, effective, and well-tolerated therapies. Antibody-drug conjugates (ADCs) are a new targeted therapeutic modality that can efficiently kill tumor cells. This review aims to summarize the composition, research, and development history and mechanism of action of ADCs, to review the research progress of ADCs in the treatment of cervical cancer, and to summarize and prospect the application of ADCs.

The complement system as a key modulator of the oral microbiome in health and disease

In this review, we address the interplay between the complement system and host microbiomes in health and disease, focussing on oral bacteria known to contribute to homeostasis or to promote dysbiosis associated with dental caries and periodontal diseases. Host proteins modulating complement activities in the oral environment and expression profiles of complement proteins in oral tissues were described. In addition, we highlight a sub-set of bacterial proteins involved in complement evasion and/or dysregulation previously characterized in pathogenic species (or strains), but further conserved among prototypical commensal species of the oral microbiome. Potential roles of these proteins in host-microbiome homeostasis and in the emergence of commensal strain lineages with increased virulence were also addressed. Finally, we provide examples of how commensal bacteria might exploit the complement system in competitive or cooperative interactions within the complex microbial communities of oral biofilms. These issues highlight the need for studies investigating the effects of the complement system on bacterial behaviour and competitiveness during their complex interactions within oral and extra-oral host sites.

Decoupling FcRn and tumor contributions to elevated immune checkpoint inhibitor clearance in cancer cachexia

High baseline clearance of immune checkpoint inhibitors (ICIs), independent of dose or systemic exposure, is associated with cachexia and poor outcomes in cancer patients. Mechanisms linking ICI clearance, cachexia and ICI therapy failure are unknown. Here, we evaluate in four murine models and across multiple antibodies whether altered baseline catabolic clearance of administered antibody requires a tumor and/or cachexia and whether medical reversal of cachexia phenotype can alleviate altered clearance. Key findings include mild cachexia phenotype and lack of elevated pembrolizumab clearance in the MC38 tumor-bearing model. We also observed severe cachexia and decreased, instead of increased, baseline pembrolizumab clearance in the tumor-free cisplatin-induced cachexia model. Liver Fcgrt expression correlated with altered baseline catabolic clearance, though elevated clearance was still observed with antibodies having no (human IgA) or reduced (human H310Q IgG1) FcRn binding. We conclude cachexia phenotype coincides with altered antibody clearance, though tumor presence is neither sufficient nor necessary for altered clearance in immunocompetent mice. Magnitude and direction of clearance alteration correlated with hepatic Fcgrt, suggesting changes in FcRn expression and/or recycling function may be partially responsible, though factors beyond FcRn also contribute to altered clearance in cachexia.

Enhancing pharmacokinetic and pharmacodynamic properties of recombinant therapeutic proteins by manipulation of sialic acid content

The circulatory half-life of recombinant therapeutic proteins is an important pharmacokinetic attribute because it determines the dosing frequency of these drugs, translating directly to treatment cost. Thus, recombinant therapeutic glycoproteins such as monoclonal antibodies have been chemically modified by various means to enhance their circulatory half-life. One approach is to manipulate the N-glycan composition of these agents. Among the many glycan constituents, sialic acid (specifically, N-acetylneuraminic acid) plays a critical role in extending circulatory half-life by masking the terminal galactose that would otherwise be recognised by the hepatic asialoglycoprotein receptor (ASGPR), resulting in clearance of the biotherapeutic from the circulation. This review aims to provide an illustrative overview of various strategies to enhance the pharmacokinetic/pharmacodynamic properties of recombinant therapeutic proteins through manipulation of their sialic acid content.

Booster shot of inactivated SARS-CoV-2 vaccine induces potent immune responses in people living with HIV

This study aimed to investigate the immunogenicity to SARS-CoV-2 and evasive subvariants BA.4/5 in people living with HIV (PLWH) following a third booster shot of inactivated SARS-CoV-2 vaccine. We conducted a cross-sectional study in 318 PLWH and 241 healthy controls (HC) using SARS-CoV-2 immunoassays. Vaccine-induced immunological responses were compared before and after the third dose. Serum levels of IgG anti-RBD and inhibition rate of NAb were significantly elevated at the "post-third dose" sampling time compared with the pre-third dose in PLWH, but were relatively decreased in contrast with those of HCs. Induced humoral and cellular responses attenuated over time after triple-dose vaccination. The neutralizing capacity against BA.4/5 was also intensified but remained below the positive inhibition threshold. Seropositivity of SARS-CoV-2-specific antibodies in PLWH was prominently lower than that in HC. We also identified age, CD4 cell counts, time after the last vaccination, and WHO staging type of PLWH as independent factors associated with the seropositivity of antibodies. PLWH receiving booster shot of inactivated vaccines generate higher antibody responses than the second dose, but lower than that in HCs. Decreased anti-BA.4/5 responses than that of WT impede the protective effect of the third dose on Omicron prevalence.

Loureiro L, Kegler A, González Soto KE, Belter B, Rössig C, Pietzsch J, Frenz M, Bachmann M, Feldmann A. Specific and safe targeting of glioblastoma using switchable and logic-gated RevCAR T cells

Glioblastoma (GBM) is still an incurable tumor that is associated with high recurrence rate and poor survival despite the current treatment regimes. With the urgent need for novel therapeutic strategies, immunotherapies, especially chimeric antigen receptor (CAR)-expressing T cells, represent a promising approach for specific and effective targeting of GBM. However, CAR T cells can be associated with serious side effects. To overcome such limitation, we applied our switchable RevCAR system to target both the epidermal growth factor receptor (EGFR) and the disialoganglioside GD2, which are expressed in GBM. The RevCAR system is a modular platform that enables controllability, improves safety, specificity and flexibility. Briefly, it consists of RevCAR T cells having a peptide epitope as extracellular domain, and a bispecific target module (RevTM). The RevTM acts as a switch key that recognizes the RevCAR epitope and the tumor-associated antigen, and thereby activating the RevCAR T cells to kill the tumor cells. However, in the absence of the RevTM, the RevCAR T cells are switched off. In this study, we show that the novel EGFR/GD2-specific RevTMs can selectively activate RevCAR T cells to kill GBM cells. Moreover, we show that gated targeting of GBM is possible with our Dual-RevCAR T cells, which have their internal activation and co-stimulatory domains separated into two receptors. Therefore, a full activation of Dual-RevCAR T cells can only be achieved when both receptors recognize EGFR and GD2 simultaneously via RevTMs, leading to a significant killing of GBM cells both in vitro and in vivo.

Cholesterol-Conjugated siRNA Silencing Tnf for the Treatment of Liver Macrophage-Mediated Acute Inflammation in Nonalcoholic Fatty Liver Disease

Despite wide recognition as a disease of pandemic proportions, effective treatments for nonalcoholic fatty liver disease (NAFLD) remain elusive. Most of the current clinical programs aim to reduce hepatic fat accumulation and, thus, prevent downstream inflammation and fibrosis. To date, this therapeutic approach has helped identify a potential disconnect between steatosis reduction and disease resolution. Mounting preclinical evidence indicates liver inflammation may play a major role in steatosis development and fibrosis but has not garnered the same clinical representation. This may be owing to deficiencies in standard therapeutic modalities that limit their application in NAFLD. RNA interference (RNAi) is an attractive approach to targeting liver inflammation owing to its clinical safety profile, target specificity, and limited biodistribution. In this study, we characterize a simple cholesterol-short-interfering RNA (siRNA) conjugate system targeting Tnf mRNA in liver macrophages for the treatment of NAFLD. First, we observed delivery and anti-inflammatory activity in an acute liver inflammation model. In a follow-up murine NAFLD model, we observed total prevention of nearly all hallmarks of this disease: steatosis, inflammation, and fibrosis. This simple conjugate siRNA delivery system may be the first to show RNAi activity in liver macrophages and provide evidence for a novel therapeutic approach to inflammation in NAFLD.

FcγR-Mediated Trogocytosis 2.0: Revisiting History Gives Rise to a Unifying Hypothesis

There is increasing interest in the clinical implications and immunology of trogocytosis, a process in which the receptors on acceptor cells remove and internalize cognate ligands from donor cells. We have reported that this phenomenon occurs in cancer immunotherapy, in which cells that express FcγR remove and internalize CD20 and bound mAbs from malignant B cells. This process can be generalized to include other reactions including the immune adherence phenomenon and antibody-induced immunosuppression. We discuss in detail FcγR-mediated trogocytosis and the evidence supporting a proposed predominant role for liver sinusoidal endothelial cells via the action of the inhibitory receptor FcγRIIb2. We describe experiments to test the validity of this hypothesis. The elucidation of the details of FcγR-mediated trogocytosis has the potential to allow for the development of novel therapies that can potentially block or enhance this reaction, depending upon whether the process leads to unfavorable or positive biological effects.

Immunogenicity and safety of an inactivated SARS-CoV-2 vaccine in people living with HIV: A cross-sectional study

We aimed to analyze the efficacy and safety of an inactivated SARS‐CoV‐2 vaccine in people living with HIV (PLWH). A total of 143 PLWH and 50 healthy individuals were included in this study. A commercially available magnetic chemiluminescence enzyme immunoassay kit was used to detect serum IgG and IgM antibodies against SARS‐CoV‐2. Serum levels of SARS‐CoV‐2‐specific IgG were significantly higher in the control group than in the PLWH group (p = 0.001). Overall, 76% of individuals in the control group were detected with seropositivity IgG against SARS‐CoV‐2 compared to 58% in the PLWH group (p = 0.024). In PLWH with IgG seropositivity, CD4+ T‐cell counts before antiretroviral therapy (ART) was higher (p = 0.015). Multivariable analysis indicated that CD4+ T cells at IgG detection (odds ratio [OR] = 1.004, p = 0.006) and time after vaccination (OR = 0.977, p = 0.014) were independently associated with seropositivity IgG against SARS‐CoV‐2 in PLWH. Neutralizing antibody (nAb) titers in PLWH against wild‐type SARS‐CoV‐2 were similar to those in the control group (p = 0.160). The proportion of seropositive nAbs against wild‐type SARS‐CoV‐2 was also similar (95% in the control group vs. 97% in the PLWH group, p = 0.665). Similar results were obtained when nAb was detected against the delta variants with similar titers (p = 0.355) and a similar proportion of seropositive nAbs were observed (p = 0.588). All the side effects observed in our study were mild and self‐limiting. The inactivated COVID‐19 vaccine appears to be safe with good immunogenicity in Chinese PLWH.