A whole blood in vitro cytokine release assay with aqueous monoclonal antibody presentation for the prediction of therapeutic protein induced cytokine release syndrome in humans

Evaluation of THP-1 and Jurkat Cell Lines Coculture for the In Vitro Assessment of the Effects of Immunosuppressive Substances

The strong appeal to reduce animal testing calls for the development and validation of in vitro, in chemico and in silico models that would replace the need for in vivo testing and ex vivo materials. A category that requires such new approach methods is the assessment of immunosuppression that can be induced by chemicals including environmental pollutants. To assess the immunosuppressive action on monocytes and lymphocytes, we mimicked the whole-blood cytokine-release assay by preparing an in vitro coculture of THP-1 and Jurkat cell lines. We optimised its activation and investigated the effects of known immunosuppressive drugs with different mechanisms of action on the release of proinflammatory cytokines. Decreased secretion of IL-8 was achieved by several immunosuppressive mechanisms and was therefore selected as an appropriate marker of immunosuppression. A set of environmentally occurring bisphenols, BPA, BPAP, BPP, BPZ, BPE, TCBPA and BPS-MAE, were then applied to the model and BPP and BPZ were found to act as potent immunosuppressants at micromolar concentrations.

Cytokine release syndrome and cancer immunotherapies - historical challenges and promising futures

Cancer is the leading cause of death worldwide. Cancer immunotherapy involves reinvigorating the patient's own immune system to fight against cancer. While novel approaches like Chimeric Antigen Receptor (CAR) T cells, bispecific T cell engagers, and immune checkpoint inhibitors have shown promising efficacy, Cytokine Release Syndrome (CRS) is a serious adverse effect and remains a major concern. CRS is a phenomenon of immune hyperactivation that results in excessive cytokine secretion, and if left unchecked, it may lead to multi-organ failure and death. Here we review the pathophysiology of CRS, its occurrence and management in the context of cancer immunotherapy, and the screening approaches that can be used to assess CRS and de-risk drug discovery earlier in the clinical setting with more predictive pre-clinical data. Furthermore, the review also sheds light on the potential immunotherapeutic approaches that can be used to overcome CRS associated with T cell activation.

Highly sensitive in vitro cytokine release assay incorporating high-density preculture

Immunostimulatory effects of monoclonal antibodies (mAb) through binding to F_cγ receptors (F_cγR) on immune cells are a likely cause of cytokine release syndrome. However, it is difficult to detect the potential risk of F_cγR-dependent cytokine release associated with mAb in the current standard cytokine release assays (CRA), including the air-drying solid-phase method using human peripheral blood mononuclear cells (PBMC). To increase the sensitivity to detect F_cγR-dependent cytokine release due to mAb, a high-density preculture (HDC) method was incorporated into the air-drying solid-phase CRA. Here, PBMC were exposed to panitumumab, trastuzumab, rituximab, or alemtuzumab at 0.1, 0.3, 1, and 3 μg/well for 24 or 48 hr under both non-HDC and HDC conditions. T-cell agonists (anti-CD3 mAb, anti-CD28 super-agonist [SA] mAb) were used as reference mAb. Panitumumab, trastuzumab, rituximab, or alemtuzumab induced cytokine release under both non-HDC and HDC conditions, and cytokine release caused by alemtuzumab was more pronounced under HDC conditions. To investigate F_cγR involvement in cytokine release associated with panitumumab, trastuzumab, rituximab, and alemtuzumab, CRA of these four mAb were conducted with anti-F_cγRI, -F_cγRII, or -F_cγRIII F(ab')₂ fragments. The results showed cytokine release caused by trastuzumab, rituximab, and alemtuzumab was significantly suppressed by anti-F_cγRIII F(ab')₂ pretreatment, and slightly reduced by anti-F_cγRI or anti-F_cγRII pretreatment, indicating these mAb induced F_cγR (especially F_cγRIII)-dependent cytokine release from PBMC. Cytokine release caused by panitumumab was slightly suppressed by anti-F_cγRIII F(ab')₂ pretreatment. Anti-CD3 mAb and anti-CD28 SA mAb also induced significant release of cytokines under HDC conditions compared with that under non-HDC conditions. In conclusion, CRA incorporating HDC into the air-drying solid-phase method using human PBMC could sensitively capture the F_cγR-dependent cytokine release potential of mAb.

A bispecific antibody agonist of the IL-2 heterodimeric receptor preferentially promotes in vivo expansion of CD8 and NK cells

The use of recombinant interleukin-2 (IL-2) as a therapeutic protein has been limited by significant toxicities despite its demonstrated ability to induce durable tumor-regression in cancer patients. The adverse events and limited efficacy of IL-2 treatment are due to the preferential binding of IL-2 to cells that express the high-affinity, trimeric receptor, IL-2Rαβγ such as endothelial cells and T-regulatory cells, respectively. Here, we describe a novel bispecific heavy-chain only antibody which binds to and activates signaling through the heterodimeric IL-2Rβγ receptor complex that is expressed on resting T-cells and NK cells. By avoiding binding to IL-2Rα, this molecule circumvents the preferential T-reg activation of native IL-2, while maintaining the robust stimulatory effects on T-cells and NK-cells in vitro. In vivo studies in both mice and cynomolgus monkeys confirm the molecule's in vivo biological activity, extended pharmacodynamics due to the Fc portion of the molecule, and enhanced safety profile. Together, these results demonstrate that the bispecific antibody is a safe and effective IL-2R agonist that harnesses the benefits of the IL-2 signaling pathway as a potential anti-cancer therapy.

The blood endothelial cell chamber - An innovative system to study immune responses in drug development

The risk for adverse immune-mediated reactions, associated with the administration of certain immunotherapeutic agents, should be mitigated early. Infusion reactions to monoclonal antibodies and other biopharmaceuticals, known as cytokine release syndrome, can arise from the release of cytokines via the drug target cell, as well as the recruitment of immune effector cells. While several in vitro cytokine release assays have been proposed up to date, many of them lack important blood components, required for this response to occur. The blood endothelial cell chamber model is an in vitro assay, composed of freshly drawn human whole blood and cultured human primary endothelial cells. Herein, its potential to study the compatibility of immunotherapeutics with the human immune system was studied by evaluating three commercially available monoclonal antibodies and bacterial endotoxin lipopolysaccharide. We demonstrate that the anti-CD28 antibody TGN1412 displayed an adaptive cytokine release profile and a distinct IL-2 response, accompanied with increased CD3⁺ cell recruitment. Alemtuzumab exhibited a clear cytokine response with a mixed adaptive/innate source (IFNγ, TNFα and IL-6). Its immunosuppressive nature is observed in depleted CD3⁺ cells. Cetuximab, associated with low infusion reactions, showed a very low or absent stimulatory effect on proinflammatory cytokines. In contrast, bacterial endotoxin demonstrated a clear innate cytokine response, defined by TNFα, IL-6 and IL-1β release, accompanied with a strong recruitment of CD14⁺CD16⁺ cells. Therefore, the blood endothelial cell chamber model is presented as a valuable in vitro tool to investigate therapeutic monoclonal antibodies with respect to cytokine release and vascular immune cell recruitment.

Development of the first reference antibody panel for qualification and validation of cytokine release assay platforms - Report of an international collaborative study

Immunomodulatory therapeutics such as monoclonal antibodies (mAb) carry an inherent risk of undesired immune reactions. One such risk is cytokine release syndrome (CRS), a rapid systemic inflammatory response characterized by the secretion of pro-inflammatory cytokines from immune cells. It is crucial for patient safety to correctly identify potential risk of CRS prior to first-in-human dose administration. For this purpose, a variety of in vitro cytokine release assays (CRA) are routinely used as part of the preclinical safety assessment of novel therapeutic mAbs. One of the challenges for the development and comparison of CRA performance is the lack of availability of standard positive and negative control mAbs for use in assay qualification. To address this issue, the National Institute for Biological Standards and Control (NIBSC) developed a reference panel of lyophilised mAbs known to induce CRS in the clinic: human anti-CD52, mouse anti-CD3 and human superagonistic (SA) anti-CD28 mAb manufactured according to the respective published sequences of Campath-1H® (alemtuzumab, IgG1) , Orthoclone OKT-3® (muromonab, IgG2a) and TGN1412 (theralizumab, IgG4), as well as three isotype matched negative controls (human IgG1, mouse IgG2a and human IgG4, respectively). The relative capacity of these control mAbs to stimulate the release of IFN-γ, IL-2, TNF-α and IL-6 in vitro was evaluated in eleven laboratories in an international collaborative study mediated through the HESI Immuno-safety Technical Committee Cytokine Release Assay Working Group. Participants tested the NIBSC mAbs in a variety of CRA platforms established at each institution. This paper presents the results from the centralised cytokine quantification on all the plasma/supernatants corresponding to the stimulation of immune cells in the different CRA platforms by a single concentration of each mAb. Each positive control mAb induced significant cytokine release in most of the tested CRA platforms. There was a high inter-laboratory variability in the levels of cytokines produced, but similar patterns of response were observed across laboratories that replicated the cytokine release patterns previously published for the respective clinical therapeutic mAbs. Therefore, the positive and negative mAbs are suitable as a reference panel for the qualification and validation of CRAs, comparison of different CRA platforms (e.g. solid vs aqueous phase), and intra- and inter-laboratory comparison of CRA performance. Thus, the use of this panel of positive and negative control mAbs will increase the confidence in the robustness of a CRA platform to identify a potential CRS risk for novel immunomodulatory therapeutic candidates.

Bone marrow-liver-thymus (BLT) immune humanized mice as a model to predict cytokine release syndrome

Cytokine release syndrome (CRS) is a serious and potentially life-threatening complication that can be associated with biological drug products. In vitro assays or in vivo tests using nonhuman primates may fail to predict CRS due to species differences and the complexity of immune system. Therefore, model species that have human-specific immune components may improve the ability to identify CRS and enhance product safety. In this study we used bone marrow-liver-thymus (BLT) humanized mice to test muromonab (OKT3), an anti-CD3 antibody with a black box warning for CRS. Initially, we completed pilot and dose escalation studies with muromonab and showed that when the dose was increased sufficiently, BLT-humanized mice experienced serious adverse outcomes including moribundity. Full studies compared muromonab treatment with adalimumab, saline, and a group pretreated with methylprednisolone prior to muromonab. We evaluated immune cell activation using flow cytometry and cytokine expression using a custom 10-plex cytokine assay to assess levels of human TNF-α, IFN-γ, IL-2, IL-6, IL-8, IL-10, IL-13, IL-17A, IL12/23p40, and GM-CSF. Muromonab treated mice had significant increases in all cytokines tested with T-cell depletion and T-cell activation noted. Adalimumab (active) and saline (inactive) control groups did not demonstrate cytokine expression changes or alterations in T-cell numbers or activation. Further, pretreatment with methylprednisolone blunted or abrogated cytokine increases. This study demonstrates that BLT-humanized mice are capable of experiencing CRS, and could be used to screen biologics for this adverse event to enhance patient safety.

Evaluation of a TGN1412 analogue using in vitro assays and two immune humanized mouse models

Cytokine release syndrome (CRS) is a serious and potentially life-threatening complication typically associated with biological drug products. Pre-clinical testing in vitro and in vivo studies using non-human primates had failed to reliably predict CRS. To determine if bone marrow-thymus-liver (BLT) humanized mice with a fully engrafted human immune system or a CD34-humanized mouse model could predict CRS, we tested an anti-CD28 monoclonal antibody (mAb) similar to TGN1412. This TGN1412 analogue (TGN1412A) was initially tested in vitro and found to produce significant dose-dependent increases in cytokine production. For in vivo studies, adalimumab, an anti-tumor necrosis factor-alpha antibody known not to cause CRS, served as a negative control. We evaluated immune cell activation and cytokine expression in three independent experiments. In BLT humanized mice, significant increases in levels of human cytokines were identified in animals treated with anti-CD28 mAb. As expected, CD28+ cell detection was strongly reduced in the anti-CD28 treated group. Increased T cell activation was also observed. The control group did not show reductions in CD28+ T-cells and did not experience increased cytokine levels. Responses by CD34-humanized mice showed no significant differences between adalimumab and anti-CD28 treatment at doses used to test BLT-humanized mice. These results suggest that the TGN1412A produces similar results in vitro to the original TGN1412 monoclonal antibody. The BLT immune humanized mice but not the CD34 humanized mice produce both robust and specific cytokine responses and may represent a pre-clinical model to identify CRS.

Blockade of a Laminin-411-Notch Axis with CRISPR/Cas9 or a Nanobioconjugate Inhibits Glioblastoma Growth through Tumor-Microenvironment Cross-talk

There is an unmet need for the treatment of glioblastoma multiforme (GBM). The extracellular matrix, including laminins, in the tumor microenvironment is important for tumor invasion and progression. In a panel of 226 patient brain glioma samples, we found a clinical correlation between the expression of tumor vascular laminin-411 (α4β1γ1) with higher tumor grade and with expression of cancer stem cell (CSC) markers, including Notch pathway members, CD133, Nestin, and c-Myc. Laminin-411 overexpression also correlated with higher recurrence rate and shorter survival of GBM patients. We also showed that depletion of laminin-411 α4 and β1 chains with CRISPR/Cas9 in human GBM cells led to reduced growth of resultant intracranial tumors in mice and significantly increased survival of host animals compared with mice with untreated cells. Inhibition of laminin-411 suppressed Notch pathway in normal and malignant human brain cell types. A nanobioconjugate potentially suitable for clinical use and capable of crossing blood-brain barrier was designed to block laminin-411 expression. Nanobioconjugate treatment of mice carrying intracranial GBM significantly increased animal survival and inhibited multiple CSC markers, including the Notch axis. This study describes an efficient strategy for GBM treatment via targeting a critical component of the tumor microenvironment largely independent of heterogeneous genetic mutations in glioblastoma.Significance: Laminin-411 expression in the glioma microenvironment correlates with Notch and other cancer stem cell markers and can be targeted by a novel, clinically translatable nanobioconjugate to inhibit glioma growth.

Engineered hexavalent Fc proteins with enhanced Fc-gamma receptor avidity provide insights into immune-complex interactions

Autoantibody-mediated diseases are currently treated with intravenous immunoglobulin, which is thought to act in part via blockade of Fc gamma receptors, thereby inhibiting autoantibody effector functions and subsequent pathology. We aimed to develop recombinant molecules with enhanced Fc receptor avidity and thus increased potency over intravenous immunoglobulin. Here we describe the molecular engineering of human Fc hexamers and explore their therapeutic and safety profiles. We show Fc hexamers were more potent than IVIG in phagocytosis blockade and disease models. However, in human whole-blood safety assays incubation with IgG1 isotype Fc hexamers resulted in cytokine release, platelet and complement activation, whereas the IgG4 version did not. We used a statistically designed mutagenesis approach to identify the key Fc residues involved in these processes. Cytokine release was found to be dependent on neutrophil FcγRIIIb interactions with L234 and A327 in the Fc. Therefore, Fc hexamers provide unique insights into Fc receptor biology.

Tania Rowley et al. present multivalent Fc molecules with enhanced avidity for Fc gamma receptors in order to improve the treatment of autoantibody-mediated human diseases. They found several key amino acids involved in Fc receptor binding interactions.

FcγRIIIa-dependent IFN-γ release in whole blood assay is predictive of therapeutic IgG1 antibodies safety

Immunomodulatory monoclonal IgG1 antibodies developed for cancer and autoimmune disease have an inherent risk of systemic release of pro-inflammatory cytokines. In vitro cytokine release assays are currently used to predict cytokine release syndrome (CRS) risk, but the validation of these preclinical tools suffers from the limited number of characterized CRS-inducing IgG1 antibodies and the poor understanding of the mechanisms regulating cytokine release. Here, we incubated human whole blood from naïve healthy volunteers with four monoclonal IgG1 antibodies with different proven or predicted capacity to elicit CRS in clinic and measured cytokine release using a multiplex assay. We found that, in contrast to anti-CD52 antibodies (Campath-1H homolog) that elicited high level of multiple inflammatory cytokines from human blood cells in vitro, other IgG1 antibodies with CRS-inducing potential consistently induced release of a single tested cytokine, interferon (IFN)-γ, with a smaller magnitude than Campath. IFN-γ expression was observed as early as 2-4 h after incubation, mediated by natural killer cells, and dependent upon tumor necrosis factor and FcγRIII. Importantly, the magnitude of the IFN-γ response elicited by IgG1 antibodies with CRS-inducing potential was determined by donor FcγRIIIa-V158F polymorphism. Overall, our results highlight the importance of FcγRIIIa-dependent IFN-γ release in preclinical cytokine release assay for the prediction of CRS risk associated with therapeutic IgG1 antibodies.

Different players generate positive responses in two in vitro cytokine assay formats with aqueous and immobilized TGN1412 analog

To detect potential risk of severe cytokine release syndrome, in vitro assay formats with human cells have been developed. The two major testing platforms are a combination of whole blood with aqueous-phase test articles (whole blood cytokine assay, WBCA) and peripheral blood mononuclear cells with solid-phase articles (PBMC assay). Significant induction of cytokines was seen in both assays after treatment with a widely used control agent, TGN1412 or its analog CD28SA, but the WBCA cytokine profile differed from what was expected from clinical experience. In the WBCA, potential risk of CD28SA was detected by elevation of IL-8 whereas IL-2, a key cytokine after stimulation of CD28, was not induced in approximately 40% of donor samples. Therefore, further mechanistic understanding of the different responses in the in vitro assay was needed. In this study of donor samples treated with CD28SA, we compared the induction of cytokines and identified the cytokine-producing cells in the two assays. IL-2 was markedly elevated in all the donors in the PBMC assay but only in 1 of 3 donors in the WBCA. IL-8, the most sensitive biomarker in the WBCA, was produced by monocytes and granulocytes. T cells, the most relevant player in the PBMC assay with CD28SA, did not contribute to the positive response seen in two donors in the WBCA, which suggests that different players caused the positive cytokine responses to CD28SA in the two assays.

Recommendations of the Oligonucleotide Safety Working Group's Formulated Oligonucleotide Subcommittee for the Safety Assessment of Formulated Oligonucleotide-Based Therapeutics

The use of lipid formulations has greatly improved the ability to effectively deliver oligonucleotides and has been instrumental in the rapid expansion of therapeutic development programs using oligonucleotide drugs. However, the development of such complex multicomponent therapeutics requires the implementation of unique, scientifically sound approaches to the nonclinical development of these drugs, based upon a hybrid of knowledge and experiences drawn from small molecule, protein, and oligonucleotide therapeutic drug development. The relative paucity of directly applicable regulatory guidance documents for oligonucleotide therapeutics in general has resulted in the generation of multiple white papers from oligonucleotide drug development experts and members of the Oligonucleotide Safety Working Group (OSWG). The members of the Formulated Oligonucleotide Subcommittee of the OSWG have utilized their collective experience working with a variety of formulations and their associated oligonucleotide payloads, as well as their insights into regulatory considerations and expectations, to generate a series of consensus recommendations for the pharmacokinetic characterization and nonclinical safety assessment of this unique class of therapeutics. It should be noted that the focus of Subcommittee discussions was on lipid nanoparticle and other types of particulate formulations of therapeutic oligonucleotides and not on conjugates or other types of modifications of oligonucleotide structure intended to facilitate delivery.

Comparison of Avidin, Neutravidin, and Streptavidin as Nanocarriers for Efficient siRNA Delivery

Protein-based drug delivery carrier has been one of the most employed modalities in biopharmaceuticals. In this study, we have compared avidin and its two analogues, neutravidin and streptavidin, as nanocarriers for the delivery of biotin-labeled siRNA with the help of biotinylated cholesterol (targeting ligand) and protamine (condensing agent). These proteins have similar binding affinity to biotin but substantial difference in their physical and chemical characteristics. Here, we have shown how these characteristics affect the size, cellular uptake, and activity of the avidin-based siRNA nanocomplex. In contrast to avidin and streptavidin nanocomplexes, neutravidin-based nanocomplex shows very low endosome entrapment and high cytoplasmic localization at extended times. High amount of the siRNA released in the cytoplasm by neutravidin-based nanocomplex at extended times (24 h) results in extensive and sustained PCBP2 gene silencing activity in HSC-T6 rat hepatic stellate cells. Neutravidin-based nanocomplex shows significantly low exocytosis in comparison to the streptavidin-based nanocomplex. Avidin-, neutravidin-, and streptavidin-based nanocomplexes are similar in size and had no significant cytotoxicity in transfected HSC-T6 cells or inflammatory cytokine induction in a whole blood assay. Compared to free siRNA, the neutravidin-based siRNA nanocomplex exhibits higher accumulation at 2 h in the liver of the rats with CCl4-induced liver fibrosis. Neutravidin has therefore been shown to be the most promising avidin analogue for the delivery of siRNA.

Is an in vitro whole blood cytokine assay useful to detect the potential risk of severe infusion reaction of monoclonal antibody pharmaceuticals?

After the life-threatening cytokine release syndrome (CRS) occurred in the clinical study of the anti-CD28 monoclonal antibody (mAb) TGN1412, in vitro cytokine release assays using human blood cells have been proposed for non-clinical evaluation of the potential risk of CRS. Two basic assay formats are frequently used: human peripheral blood mononuclear cells (PBMC) with immobilized mAbs, and whole blood with aqueous mAbs. However, the suitability of the whole blood cytokine assay (WBCA) has been questioned, because an unrealistically large sample size would be required to detect the potential risk of CRS induced by TGN1412, which has low sensitivity. We performed a WBCA using peripheral blood obtained from 68 healthy volunteers to compare two high risk mAbs, the TGN1412 analogue anti-CD28 superagonistic mAb (CD28SA) and the FcγR-mediated alemutuzumab, with a low risk mAb, panitumumab. Based on the cytokine measurements in this study, the sample size required to detect a statistically significant increase in cytokines with 90% power and 5% significance was determined to be n = 9 for CD28SA and n = 5 for alemtuzumab. The most sensitive marker was IL-8. The results suggest that WBCA is a practical test design that can warn of the potential risk of FcγR-mediated alemtuzumab and T-cell activating CD28SA but, because there was apparently a lower response to CD28SA, it cannot be used as a risk-ranking tool. WBCA is suggested to be a helpful tool for identifying potential FcγR-mediated hazards, but further mechanistic understanding of the response to CD28SA is necessary before applying it to T cell-stimulating mAbs.

In vitro assays supporting the safety assessment of immunomodulatory monoclonal antibodies

Many monoclonal antibodies (mAbs) licensed for human use or in clinical development for cancer and autoimmune disease directly interact with the immune system. These immunomodulatory mAbs have an inherent risk of adverse immune-mediated drug reactions, including infusion reactions, cytokine storms, immunosuppression and autoimmunity. A thorough understanding of the potential for immunotoxicity of a mAb is required to support administration to humans. This review will highlight the key role of in vitro assays in defining the immunopharmacology, immunotoxicity and immunogenicity of mAbs. A wide range of in vitro tests with multiple formats of different complexity can be utilized to characterize i) the antibody-binding domains of the mAb, such as on-target binding and downstream pharmacological effects (e.g. immunosuppression, immune activation, cytokine release) in both humans and animal species used for toxicology studies and off-target binding; ii) Fc-dependent effects such as Fc-mediated cellular activation (e.g. of leukocytes, platelets) and cytokine release, complement activation; and iii) product-related factors (sequence, physical-chemical properties and impurities) that can impact both pharmacological activity and immunogenicity potential of a mAb. These assays can be crucial to the selection of mAbs with an optimum balance of safety and efficacy, in defining whether a mAb is a high risk molecule, and together with animal data, can inform human safe starting doses and escalation schemes.

Development of cell-based assay for predictively evaluating the FcγR-mediated human immune cell activation by therapeutic monoclonal antibodies

Therapeutic monoclonal antibodies (mAbs) have important roles in treatments for various cancers and inflammatory diseases. Their highly target specificities provide controlled safety profiles. However, therapeutic mAbs commonly pose a risk of the induction of the release of cytokines, which may result in adverse events including infusion reaction and cytokine release syndrome. Several mechanisms are involved in the cytokine releases induced by therapeutic mAbs, and the activation of immune effector cells via Fcγ receptors (FcγRs) is one of the putative mechanisms for most IgG-subclass mAbs. The relationship between cytokine releases and mAbs' Fc functions is not fully understood. Here we developed a simple reporter cell-based assay for estimating the FcγR-mediated activation of human immune effector cells by mAbs. Our use of the cell-based assay to compare Fc-engineered mAbs with different FcγR-activation profiles revealed that the releases of inflammatory cytokines and chemokines from human peripheral blood mononuclear cells (hPBMCs) induced by the mAbs were elevated by treatment with Fc-engineered mAbs with higher FcγR-activation properties. Our results also suggested the involvement of monocytic effector cells in the activation of hPBMCs as sources of released cytokines and chemokines, which may lead to the immune cell-mediated adverse events. Our new reporter cell assay is a promising tool for evaluating and predicting the activation of human immune cells by novel Fc-engineered mAbs.

Translational immunotoxicology of immunomodulatory monoclonal antibodies

While immunomodulatory monoclonal antibodies (mAbs) have a wide therapeutic potential, exaggerated immunopharmacology may drive both acute and delayed immunotoxicity. The existing tools for immunotoxicity assessment do not accurately predict the full range of immunotoxicities observed in humans. New and optimized models, assays, endpoints and biomarkers in animals and humans are required to safeguard patients and allow them access to these often transformational therapies.

Cytokine release: A workshop proceedings on the state-of-the-science, current challenges and future directions

In October 2013, the International Life Sciences Institute - Health and Environmental Sciences Institute Immunotoxicology Technical Committee (ILSI-HESI ITC) held a one-day workshop entitled, "Workshop on Cytokine Release: State-of-the-Science, Current Challenges and Future Directions". The workshop brought together scientists from pharmaceutical, academic, health authority, and contract research organizations to discuss novel approaches and current challenges for the use of in vitro cytokine release assays (CRAs) for the identification of cytokine release syndrome (CRS) potential of novel monoclonal antibody (mAb) therapeutics. Topics presented encompassed a regulatory perspective on cytokine release and assessment, case studies regarding the translatability of preclinical cytokine data to the clinic, and the latest state of the science of CRAs, including comparisons between mAb therapeutics within one platform and across several assay platforms, a novel physiological assay platform, and assay optimization approaches such as determination of FcR expression profiles and use of statistical tests. The data and approaches presented confirmed that multiple CRA platforms are in use for identification of CRS potential and that the choice of a particular CRA platform is highly dependent on the availability of resources for individual laboratories (e.g. positive and negative controls, number of human blood donors), the assay through-put required, and the mechanism-of-action of the therapeutic candidate to be tested. Workshop participants agreed that more data on the predictive performance of CRA platforms is needed, and current efforts to compare in vitro assay results with clinical cytokine assessments were discussed. In summary, many laboratories continue to focus research efforts on the improvement of the translatability of current CRA platforms as well explore novel approaches which may lead to more accurate, and potentially patient-specific, CRS prediction in the future.

Cytokine release assays for the prediction of therapeutic mAb safety in first-in man trials--Whole blood cytokine release assays are poorly predictive for TGN1412 cytokine storm

The therapeutic monoclonal antibody (mAb) TGN1412 (anti-CD28 superagonist) caused near-fatal cytokine release syndrome (CRS) in all six volunteers during a phase-I clinical trial. Several cytokine release assays (CRAs) with reported predictivity for TGN1412-induced CRS have since been developed for the preclinical safety testing of new therapeutic mAbs. The whole blood (WB) CRA is the most widely used, but its sensitivity for TGN1412-like cytokine release was recently criticized. In a comparative study, using group size required for 90% power with 5% significance as a measure of sensitivity, we found that WB and 10% (v/v) WB CRAs were the least sensitive for TGN1412 as these required the largest group sizes (n = 52 and 79, respectively). In contrast, the peripheral blood mononuclear cell (PBMC) solid phase (SP) CRA was the most sensitive for TGN1412 as it required the smallest group size (n = 4). Similarly, the PBMC SP CRA was more sensitive than the WB CRA for muromonab-CD3 (anti-CD3) which stimulates TGN1412-like cytokine release (n = 4 and 4519, respectively). Conversely, the WB CRA was far more sensitive than the PBMC SP CRA for alemtuzumab (anti-CD52) which stimulates FcγRI-mediated cytokine release (n = 8 and 180, respectively). Investigation of potential factors contributing to the different sensitivities revealed that removal of red blood cells (RBCs) from WB permitted PBMC-like TGN1412 responses in a SP CRA, which in turn could be inhibited by the addition of the RBC membrane protein glycophorin A (GYPA); this observation likely underlies, at least in part, the poor sensitivity of WB CRA for TGN1412. The use of PBMC SP CRA for the detection of TGN1412-like cytokine release is recommended in conjunction with adequately powered group sizes for dependable preclinical safety testing of new therapeutic mAbs.

An autologous endothelial cell:peripheral blood mononuclear cell assay that detects cytokine storm responses to biologics

There is an urgent unmet need for human tissue bioassays to predict cytokine storm responses to biologics. Current bioassays that detect cytokine storm responses in vitro rely on endothelial cells, usually from umbilical veins or cell lines, cocultured with freshly isolated peripheral blood mononuclear cells (PBMCs) from healthy adult volunteers. These assays therefore comprise cells from 2 separate donors and carry the disadvantage of mismatched tissues and lack the advantage of personalized medicine. Current assays also do not fully delineate mild (such as Campath) and severe (such as TGN1412) cytokine storm-inducing drugs. Here, we report a novel bioassay where endothelial cells grown from stem cells in the peripheral blood (blood outgrowth endothelial cells) and PBMCs from the same donor can be used to create an autologous coculture bioassay that responds by releasing a plethora of cytokines to authentic TGN1412 but only modestly to Campath and not to control antibodies such as Herceptin, Avastin, and Arzerra. This assay performed better than the traditional mixed donor assay in terms of cytokine release to TGN1412 and, thus, we suggest provides significant advancement and a definitive system by which biologics can be tested and paves the way for personalized medicine.

Alternative methods in toxicology: CFU assays application, limitation and future prospective

Blood is a fluid connective tissue which plays a vital role for normal body function. It consist different type of blood cells which is continuously reproduce inside the bone marrow from hematopoietic system. Xenobiotics could be specifically toxic to the hematopoietic system and they can cause hematological disorders by disturbing the normal functions. In vitro hematopoietic colony-forming cell assays play a crucial role to evaluate potential toxic effects of new xenobiotics and also helpful in bridging the gap between preclinical toxicology studies in animal models and clinical investigations. Use of these assays in conjunction with, high-throughput screening reduces the cost and time associated with these assays. This article provides a critical view over in vitro hematopoietic colony-forming cell assays in assessment of hematotoxicity.

Delayed hypersensitivity reaction resulting in maculopapular-type eruption due to entecavir in the treatment of chronic hepatitis B

Several clinical trials have demonstrated the potent antiviral efficacy of entecavir (ETV), and this relatively new nucleoside analogue drug has rapidly become a frequently prescribed therapy for chronic hepatitis B (CHB) worldwide. While the studies have also shown a good overall safety profile for ETV, adverse drug reactions (ADRs) in patients with advanced cirrhosis have been reported and represent a broad spectrum of drug-induced injuries, including lactic acidosis, myalgia, neuropathy, azotemia, hypophosphatemia, muscular weakness, and pancreatitis, as well as immune-mediated responses (i.e., allergic reactions). Cutaneous ADRs associated with ETV are very rare, with only two case reports in the publicly available literature; both of these cases were classified as unspecified hypersensitivity allergic (type I) ADR, but neither were reported as pathologically proven or as evaluated by cytokine release analysis. Here, we report the case of a 45-year-old woman who presented with a generalized maculopapular rash after one week of ETV treatment for lamivudine-resistant CHB. The patient reported having experienced a similar skin eruption during a previous three-month regimen of ETV, for which she had self-discontinued the medication. Histopathological analysis of a skin biopsy showed acanthotic epidermis with focal parakeratosis and a perivascular lymphocytic infiltrate admixed with interstitial eosinophils in the papillary and reticular dermis, consistent with a diagnosis of drug sensitivity. A lymphocyte stimulation test showed significantly enhanced IL-4, indicating a classification of type IVb delayed hypersensitivity. The patient was switched to an adefovir-lamivudine combination regimen and the skin eruption resolved two weeks after the ETV withdrawal. This case represents the first pathologically and immunologically evidenced ETV-induced delayed type hypersensitivity skin reaction reported to date. Physicians should be aware of the potential, although rare, for cutaneous ADRs associated with ETV treatment.

Structure and antitumor and immunomodulatory activities of a water-soluble polysaccharide from Dimocarpus longan pulp

A new water-soluble polysaccharide (longan polysaccharide 1 (LP1)) was extracted and successfully purified from Dimocarpus longan pulp via diethylaminoethyl (DEAE)-cellulose anion-exchange and Sephacryl S-300 HR gel chromatography. The chemical structure was determined using Infrared (IR), gas chromatography (GC) and nuclear magnetic resonance (NMR) analysis. The results indicated that the molecular weight of the sample was 1.1 × 10(5) Da. Monosaccharide composition analysis revealed that LP1 was composed of Glc, GalA, Ara and Gal in a molar ratio of 5.39:1.04:0.74:0.21. Structural analysis indicated that LP1 consisted of a backbone of → 4)-α-D-Glcp-(1 → 4)-α-D-GALPA-(1 → 4)-α-D-Glcp-(1 → 4)-β-D-Glcp-(1 → units with poly saccharide side chains composed of → 2)-β-D-Fruf-(1 → 2)-L-sorbose-(1 → attached to the O-6 position of the α-D-Glcp residues. In vitro experiments indicated that LP1 had significantly high antitumor activity against SKOV3 and HO8910 tumor cells, with inhibition percentages of 40% and 50%, respectively. In addition, LP1 significantly stimulated the production of the cytokine interferon-γ (IFN-γ), increased the activity of murine macrophages and enhanced B- and T-lymphocyte proliferation. The results of this study demonstrate that LP1 has potential applications as a natural antitumor agent with immunomodulatory activity.

Cytokine release assays: current practices and future directions

As a result of the CD28 superagonist biotherapeutic monoclonal antibody (TGN 1412) "cytokine storm" incident, cytokine release assays (CRA) have become hazard identification and prospective risk assessment tools for screening novel biotherapeutics directed against targets having a potential risk for eliciting adverse pro-inflammatory clinical infusion reactions. Different laboratories may have different strategies, assay formats, and approaches to the reporting, interpretation, and use of data for either decision making or risk assessment. Additionally, many independent contract research organizations (CROs), academic and government laboratories are involved in some aspect of CRA work. As a result, while some pharmaceutical companies are providing CRA data as part of the regulatory submissions when necessary, technical and regulatory practices are still evolving to provide data predictive of cytokine release in humans and that are relevant to safety. This manuscript provides an overview of different approaches employed by the pharmaceutical industry and CROs, for the use and application of CRA based upon a survey and post survey follow up conducted by ILSI-Health and Environmental Sciences Institute (HESI) Immunotoxicology Committee CRA Working Group. Also discussed is ongoing research in the academic sector, the regulatory environment, current limitations of the assays, and future directions and recommendations for cytokine release assays.

Prediction and prevention of the next pandemic zoonosis

Most pandemics--eg, HIV/AIDS, severe acute respiratory syndrome, pandemic influenza--originate in animals, are caused by viruses, and are driven to emerge by ecological, behavioural, or socioeconomic changes. Despite their substantial effects on global public health and growing understanding of the process by which they emerge, no pandemic has been predicted before infecting human beings. We review what is known about the pathogens that emerge, the hosts that they originate in, and the factors that drive their emergence. We discuss challenges to their control and new efforts to predict pandemics, target surveillance to the most crucial interfaces, and identify prevention strategies. New mathematical modelling, diagnostic, communications, and informatics technologies can identify and report hitherto unknown microbes in other species, and thus new risk assessment approaches are needed to identify microbes most likely to cause human disease. We lay out a series of research and surveillance opportunities and goals that could help to overcome these challenges and move the global pandemic strategy from response to pre-emption.