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Background A previous study demonstrated that N-glycosylation profiles of IgG are associated with subclinical atherosclerosis in a British population. However, the generalisability of this finding to other ethnic groups remains to be investigated, and it has yet to account for additional traditional atherosclerotic risk factors. The present study, thus, aims to explore IgG N-glycosylation profiles in Han Chinese with atherosclerosis, and their potential role in atherosclerosis, while controlling for traditional atherosclerotic risk factors. Methods Data of this case-control study were obtained from an established umbrella Health Examination Cohort Study (registration number: ChiCTR2100048740). The investigation was conducted at the Health Care Centre of the First Affiliated Hospital of Shantou University Medical College in China, from August 1, 2021, to July 31, 2022. A sample of 69 carotid atherosclerosis (CAS) cases was recruited from the umbrella cohort, along with 69 controls without carotid atherosclerosis, matched by traditional atherosclerosis-related risk factors, including gender, age, smoking, alcohol consumption, hypertension, diabetes, dyslipidemia and obesity. Subsequently, serum IgG N-glycosylation was profiled using Ultra-Performance Liquid Chromatography. Results After propensity score matching, the relative abundance of IgG fucosylation in CAS cases was significantly lower than that in controls [95.32 (92.96, 95.99) vs. 95.96 (94.70, 96.58), P  = 0.022]. The traditional atherosclerosis-related risk factors showed no statistically significant difference between CAS cases and controls ( P  > 0.05). Conclusions The reduced fucosylation of IgG in CAS cases underscores the pivotal role of afucosylation in CAS. Enhancing the inflammatory capability of IgG via initiating antibody-dependent cell-mediated cytotoxicity could be the potential mechanism behind this, which should be further verified by functional studies.

Clinical application of PD-1 and PD-L1 monoclonal antibodies (mAbs) is hindered by their relatively low response rates and the occurrence of drug resistance. Co-expression of B7-H3 with PD-L1 has been found in various solid tumors, and combination therapies that target both PD-1/PD-L1 and B7-H3 pathways may provide  additional therapeutic benefits. Up to today, however, no bispecific antibodies targeting both PD-1 and B7-H3 have reached the clinical development stage. In this study, we generated a stable B7-H3×PD-L1 bispecific antibody (BsAb) in IgG1-VHH format by coupling a humanized IgG1 mAb against PD-L1 with a humanized camelus variable domain of the heavy-chain of heavy-chain antibody (VHH) against human B7-H3. The BsAb exhibited favorable thermostability, efficient T cell activation, IFN-γ production, and antibody-dependent cell-mediated cytotoxicity (ADCC). In a PBMC humanized A375 xenogeneic tumor model, treatment with BsAb (10 mg/kg, i.p., twice a week for 6 weeks) showed enhanced antitumor activities compared to monotherapies and, to some degree, combination therapies. Our results suggest that targeting both PD-1 and B7-H3 with BsAbs increases their specificities to B7-H3 and PD-L1 double-positive tumors and induces a synergetic effect. We conclude that B7-H3×PD-L1 BsAb is favored over mAbs and possibly combination therapies in treating B7-H3 and PD-L1 double-positive tumors.

Human natural killer (NK) cells can target tumor cells in an antigen-specific manner by the recognition of cell bound antibodies. This process induces antibody-dependent cell-mediated cytotoxicity (ADCC) and is exclusively mediated by the low affinity IgG Fc receptor CD16A (FcγRIIIA). Exploiting ADCC by NK cells is a major area of emphasis for advancing cancer immunotherapies. CD64 (FcγRI) is the only high affinity IgG FcR and it binds to the same IgG isotypes as CD16A, but it is not expressed by human NK cells. We have generated engineered human NK cells expressing recombinant CD64 with the goal of increasing their ADCC potency. Preclinical testing of this approach is essential for establishing efficacy and safety of the engineered NK cells. The dog provides particular advantages as a model, which includes spontaneous development of cancer in the setting of an intact and outbred immune system. To advance this immunotherapy model, we cloned canine CD16A and CD64 and generated specific mAbs. We report here for the first time the expression patterns of these FcγRs on dog peripheral blood leukocytes. CD64 was expressed by neutrophils and monocytes, but not lymphocytes, while canine CD16A was expressed at high levels by a subset of monocytes and lymphocytes. These expression patterns are similar to that of human leukocytes. Based on phenotypic characteristics, the CD16A + lymphocytes consisted of T cells (CD3 + CD8 + CD5 dim α/β TCR + ) and NK cells (CD3 − CD5 − CD94 + ), but not B cells. Interestingly, the majority of canine CD16A + lymphocytes were from the T cell population. Like human CD16A, canine CD16A was downregulated by a disintegrin and metalloproteinase 17 (ADAM17) upon leukocyte activation, revealing a conserved means of regulation. We also directly demonstrate that both canine CD16A and CD64 can induce ADCC when expressed in the NK cell line NK-92. These findings pave the way to engineering canine NK cells or T cells with high affinity recombinant canine CD64 to maximize ADCC and to test their safety and efficacy to benefit both humans and dogs.

Opinion statement Monoclonal antibody (mAb) therapy is now considered a main component of cancer therapy in Australia. Although traditionally thought of as pure signalling inhibitors, a large proponent of these medications function through antibody-dependent cell-mediated cytotoxicity (ADCC). Currently, most protocols and institutional guidelines for ADCC-mediated mAbs promote the use of corticosteroids as premedication: this is implemented to reduce infusion-related reactions (IRRs) and antiemesis prophylaxis and combat concurrently administered chemotherapy-related syndromes. Concerningly, the inhibitory effects of ADCC by corticosteroids are well documented; henceforth, it is possible the current standard of care is misaligned to the literature surrounding ADCC. Subsequently, clinicians’ decisions to act in contrast to this literature may be reducing the efficacy of mAbs. The literature suggests that the redundant use of corticosteroids should be cautioned against when used in conjunction with ADCC-mediated mAbs—this is due to the consequent reduction in anti-tumour activity. Owing to the fact IRRs typically occur upon initial infusion, the authors advocate for individual clinicians and institutional protocols to considering augmenting their practice to corticosteroid premedication at the first dose only, unless clinically indicated. Additionally, product information (PI) and consumer medicine information (CMI) documents distributed by Australian and international regulatory agencies should consider disclosing the risk of concurrent steroids with these medications. Moreover, the authors suggest considering alternative medications for the management of side effects.

Background Cetuximab has been approved for use for first-line treatment of patients with wild-type KRAS metastatic colorectal cancer (CRC). However, treatment with cetuximab has shown limited efficacy as a CRC monotherapy. In addition, natural killer (NK) cell function is known to be severely attenuated in cancer patients. The goal of this study was to develop a new strategy to enhance antibody-dependent cell-mediated cytotoxicity (ADCC) mediated by NK cells, in combination with cetuximab against CRC cells. Methods Ex vivo expanded NK cells were stimulated with reovirus, and reovirus-activated NK cells mediated ADCC assay were performed on CRC cells in combination with cetuximab. The synergistic antitumor effects of reovirus-activated NK cells and cetuximab were tested on DLD-1 tumor-bearing mice. Finally, Toll-like receptor 3 (TLR3) knockdown in NK cells, along with chemical blockade of TLR3/dsRNA complex, and inhibition of the TLR3 downstream signaling pathway, were performed to explore the mechanisms by which reovirus enhances NK cell cytotoxicity. Results We first confirmed that exposure of NK cells to reovirus enhanced their cytotoxicity in a dose-dependent manner.We then investigated whether reovirus-activated NK cells exposed to cetuximab-bound CRC cells exhibited greater anti-tumor efficacy than either monotherapy. Co-culture of CRC cell lines with reovirus-activated NK cells indicated that NK cytotoxicity was significantly higher in combination with cetuximab, regardless of KRAS mutation status or EGFR expression level. We also found that reovirus activation of NK cells, in conjunction with cetuximab, resulted in significantly stronger anti-tumor efficacy.Finally, TLR3 knockdown, inhibition of TLR3/dsRNA complex or TBK1/IKKε demonstrated that activation of NK cells by reovirus was dependent on TLR3 and its downstream signaling pathway. Conclusions This study demonstrated that combination treatment of reovirus-activated NK cells with cetuximab synergistically enhances their anti-tumor cytotoxicity, suggesting a strong candidate strategy for clinical treatment of CRC.

Background: Native cluster of differentiation (CD) 19 targeting antibodies are poorly effective in triggering antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC), which are crucial effector functions of therapeutic antibodies in cancer immunotherapy. Both functions can be enhanced by engineering the antibody’s Fc region by altering the amino acid sequence (Fc protein-engineering) or the Fc-linked glycan (Fc glyco-engineering). We hypothesized that combining Fc glyco-engineering with Fc protein-engineering will rescue ADCC and CDC in CD19 antibodies. Results: Four versions of a CD19 antibody based on tafasitamab’s V-regions were generated: a native IgG1, an Fc protein-engineered version with amino acid exchanges S267E/H268F/S324T/G236A/I332E (EFTAE modification) to enhance CDC, and afucosylated, Fc glyco-engineered versions of both to promote ADCC. Irrespective of fucosylation, antibodies carrying the EFTAE modification had enhanced C1q binding and were superior in inducing CDC. In contrast, afucosylated versions exerted an enhanced affinity to Fcγ receptor IIIA and had increased ADCC activity. Of note, the double-engineered antibody harboring the EFTAE modification and lacking fucose triggered both CDC and ADCC more efficiently. Conclusions: Fc glyco-engineering and protein-engineering could be combined to enhance ADCC and CDC in CD19 antibodies and may allow the generation of antibodies with higher therapeutic efficacy by promoting two key functions simultaneously.

The epidermal growth factor receptor (EGFR) is a validated therapeutic target for RAS/RAF wild‐type colorectal cancer (CRC). However, monoclonal antibody‐based anti‐EGFR therapies such as cetuximab have limited effectiveness. Herein, it is identified that EGFR internalization is associated with poor treatment response and prognosis in patients with CRC, based on a retrospective analysis of patients treated with cetuximab. It is further demonstrated that the endocytosis inhibitor prochlorperazine (PCZ) can move EGFR, which is hidden inside the cell, to the cell surface to improve therapeutic antibody binding. Thus, a thermosensitive hydrogel co‐loaded with cetuximab and PCZ (Gel@Cmab/PCZ) is constructed for sustained inhibition of endocytosis and effective cetuximab delivery. Peritumoral injection of Gel@Cmab/PCZ shows strong antitumor efficacy in subcutaneous and orthotopic CRC tumor models and completely abrogated liver metastasis when combined with chemotherapy. In a humanized patient‐derived xenograft model, a single injection of Gel@Cmab/PCZ with one‐third of the conventional cetuximab dose achieved 91% tumor growth inhibition, which promoted NK cell infiltration into tumor tissues and their antibody‐dependent cell‐mediated cytotoxicity effect. This study represents a novel strategy to boost the monoclonal antibody‐mediated anti‐tumor response in CRC. In this study, a thermosensitive hydrogel loaded with cetuximab and endocytosis inhibitor prochlorperazine is designed to enhance the therapeutic efficacy of colorectal cancer. The hydrogel can sustainably release prochlorperazine at the tumor site, which led to the increased expression of EGFR on the cell membrane, and thus enhances antibody‐dependent cell‐mediated cytotoxicity of cetuximab. This strategy boosts antibody‐mediated anti‐tumor response in multiple tumor models.

Natural killer (NK) cells of the innate immune system are cytotoxic lymphocytes that play an important roles following transplantation of solid organs and hematopoietic stem cells. Recognition of self-human leukocyte antigen (HLA) class I molecules by inhibitory killer cell immunoglobulin-like receptors (KIRs) is involved in the calibration of NK cell effector capacities during the developmental stage, allowing the subsequent recognition and elimination of target cells with decreased expression of self-HLA class I (due to virus infection or tumor transformation) or HLA class I disparities (in the setting of allogeneic transplantation). NK cells expressing an inhibitory KIR-binding self-HLA can be activated when confronted with allografts lacking a ligand for the inhibitory receptor. Following the response of the adaptive immune system, NK cells can further destroy allograft endothelium by antibody-dependent cell-mediated cytotoxicity (ADCC), triggered through cross-linking of the CD16 Fc receptor by donor-specific antibodies bound to allograft. Upon recognizing allogeneic target cells, NK cells also secrete cytokines and chemokines that drive maturation of dendritic cells to promote cellular and humoral adaptive immune responses against the allograft. The cumulative activating and inhibitory signals generated by ligation of the receptors regulates mature NK cell killing of target cells and their production of cytokines and chemokines. This review summarizes the role of NK cells in allograft rejection and proposes mechanistic concepts that indicate a prominent role for KIR-HLA interactions in facilitating NK cells for Fc receptor-mediated ADCC effector function involved in antibody-mediated rejection of solid organ transplants.

A current view is that cytotoxic stress, such as DNA damage, induces apoptosis by regulating the permeability of mitochondria. Mitochondria sequester several proteins that, if released, kill by activating caspases, the proteases that disassemble the cell. Cytokines activate caspases in a different way, by assembling receptor complexes that activate caspases directly; in this case, the subsequent mitochondrial permeabilization accelerates cell disassembly by amplifying caspase activity. We found that cytotoxic stress causes activation of caspase-2, and that this caspase is required for the permeabilization of mitochondria. Therefore, we argue that cytokine-induced and stress-induced apoptosis act through conceptually similar pathways in which mitochondria are amplifiers of caspase activity rather than initiators of caspase activation.

Two molecular mechanisms of T cell-mediated cytotoxicity, one perforin-based, the other Fas-based, have been demonstrated. To determine the extent of their contribution to T cell-mediated cytotoxicity, a range of effector cells from normal control or perforin-deficient mice were tested against a panel of target cells with various levels of Fas expression. All cytotoxicity observed was due to either of these mechanisms, and no third mechanism was detected. Thus, the perforin- and Fas-based mechanisms may account for all T cell-mediated cytotoxicity in short-term in vitro assays.