Determination of starting dose of the T cell-redirecting bispecific antibody ERY974 targeting glypican-3 in first-in-human clinical trial.

Currently, ERY974, a humanized IgG4 bispecific T cell-redirecting antibody recognizing glypican-3 and CD3, is in phase I clinical trials. After a first-in-human clinical trial of an anti-CD28 agonist monoclonal antibody resulting in severe life-threatening adverse events, the minimal anticipated biological effect level approach has been considered for determining the first-in-human dose of high-risk drugs. Accordingly, we aimed to determine the first-in-human dose of ERY974 using both the minimal anticipated biological effect level and no observed adverse effect level approaches. In the former, we used the 10% effective concentration value from a cytotoxicity assay using the huH-1 cell line with the highest sensitivity to ERY974 to calculate the first-in-human dose of 4.9 ng/kg, at which maximum drug concentration after 4 h of intravenous ERY974 infusion was equal to the 10% effective concentration value. To determine the no observed adverse effect level, we conducted a single-dose study in cynomolgus monkeys that were intravenously infused with ERY974 (0.1, 1, and 10 µg/kg). The lowest dose of 0.1 µg/kg was determined as the no observed adverse effect level, and the first-in-human dose of 3.2 ng/kg was calculated, considering body surface area and species difference. For the phase I clinical trial, we selected 3.0 ng/kg as a starting dose, which was lower than the first-in-human dose calculated from both the no observed adverse effect level and minimal anticipated biological effect level. Combining these two methods to determine the first-in-human dose of strong immune modulators such as T cell-redirecting antibodies would be a suitable approach from safety and efficacy perspectives.Clinical trial registration: JapicCTI-194805/NCT05022927.

An anti-glypican 3/CD3 bispecific T cell-redirecting antibody for treatment of solid tumors.

Cancer care is being revolutionized by immunotherapies such as immune checkpoint inhibitors, engineered T cell transfer, and cell vaccines. The bispecific T cell-redirecting antibody (TRAB) is one such promising immunotherapy, which can redirect T cells to tumor cells by engaging CD3 on a T cell and an antigen on a tumor cell. Because T cells can be redirected to tumor cells regardless of the specificity of T cell receptors, TRAB is considered efficacious for less immunogenic tumors lacking enough neoantigens. Its clinical efficacy has been exemplified by blinatumomab, a bispecific T cell engager targeting CD19 and CD3, which has shown marked clinical responses against hematological malignancies. However, the success of TRAB in solid tumors has been hampered by the lack of a target molecule with sufficient tumor selectivity to avoid "on-target off-tumor" toxicity. Glypican 3 (GPC3) is a highly tumor-specific antigen that is expressed during fetal development but is strictly suppressed in normal adult tissues. We developed ERY974, a whole humanized immunoglobulin G-structured TRAB harboring a common light chain, which bispecifically binds to GPC3 and CD3. Using a mouse model with reconstituted human immune cells, we revealed that ERY974 is highly effective in killing various types of tumors that have GPC3 expression comparable to that in clinical tumors. ERY974 also induced a robust antitumor efficacy even against tumors with nonimmunogenic features, which are difficult to treat by inhibiting immune checkpoints such as PD-1 (programmed cell death protein-1) and CTLA-4 (cytotoxic T lymphocyte-associated protein-4). Immune monitoring revealed that ERY974 converted the poorly inflamed tumor microenvironment to a highly inflamed microenvironment. Toxicology studies in cynomolgus monkeys showed transient cytokine elevation, but this was manageable and reversible. No organ toxicity was evident. These data provide a rationale for clinical testing of ERY974 for the treatment of patients with GPC3-positive solid tumors.

Effects of SA237, a humanized anti-interleukin-6 receptor monoclonal antibody, on pre- and postnatal development in cynomolgus monkey.

BACKGROUND: SA237 is a humanized anti-interleukin-6 receptor (IL-6R) monoclonal antibody in which the constant and variable regions have been engineered for a longer plasma half-life. According to literature, blocking of IL-6 related functions could have an influence on pregnancy sustainment, development of the immune system, and brain growth. METHODS: SA237 effects on dams, embryo-fetal development, parturition and postnatal development were investigated in an enhanced pre- and postnatal development study, in which SA237 was subcutaneously administered to pregnant cynomolgus monkeys at dose levels of 2 or 50 mg/kg once weekly from gestation day 20 until parturition. Infant development, including immune function and learning ability tests, was comprehensively assessed at multiple examinations until approximately 10 months after birth. RESULTS: SA237 plasma concentrations were almost equivalent between dams and their infants and dropped throughout the postnatal period, pharmacologically relevant exposure was maintained for 147 days after birth at 50 mg/kg. Because the binding of SA237 to IL-6R inhibited IL-6R-mediated clearance of IL-6, serum IL-6 increased in dams and infants. However, there were no SA237-related adverse effects on dams, embryos, fetuses, or infants. SA237 pharmacological effects contributed to the suppression of plasma cell differentiation and antibody production by inhibiting IL-6 signaling, and T cell-dependent antibody reaction was minimally suppressed in infants, but physiological immunoglobulin class switching and general antibody production against a T cell-dependent antigen were maintained. CONCLUSION: The exposure to SA237 did not adversely affect dams, embryo-fetal development, parturition, and postnatal development, including immune function and neuronal development. Birth Defects Research 109:843-856, 2017. © 2017 Wiley Periodicals, Inc.

Safety and immunotoxicity assessment of immunomodulatory monoclonal antibodies.

Most therapeutic monoclonal antibodies (mAbs) licensed for human use or in clinical development are indicated for treatment of patients with cancer and inflammatory/autoimmune disease and as such, are designed to directly interact with the immune system. A major hurdle for the development and early clinical investigation of many of these immunomodulatory mAbs is their inherent risk for adverse immune-mediated drug reactions in humans such as infusion reactions, cytokine storms, immunosuppression and autoimmunity. A thorough understanding of the immunopharmacology of a mAb in humans and animals is required to both anticipate the clinical risk of adverse immunotoxicological events and to select a safe starting dose for first-in-human (FIH) clinical studies. This review summarizes the most common adverse immunotoxicological events occurring in humans with immunomodulatory mAbs and outlines non-clinical strategies to define their immunopharmacology and assess their immunotoxic potential, as well as reduce the risk of immunotoxicity through rational mAb design. Tests to assess the relative risk of mAb candidates for cytokine release syndrome, innate immune system (dendritic cell) activation and immunogenicity in humans are also described. The importance of selecting a relevant and sensitive toxicity species for human safety assessment in which the immunopharmacology of the mAb is similar to that expected in humans is highlighted, as is the importance of understanding the limitations of the species selected for human safety assessment and supplementation of in vivo safety assessment with appropriate in vitro human assays. A tiered approach to assess effects on immune status, immune function and risk of infection and cancer, governed by the mechanism of action and structural features of the mAb, is described. Finally, the use of immunopharmacology and immunotoxicity data in determining a minimum anticipated biologic effect Level (MABEL) and in the selection of safe human starting dose is discussed.

Immunotoxicity testing in nonhuman primates.

Biological relevance is generally the major justification for using nonhuman primates (NHP) during preclinical safety assessment. This holds particularly true for the evaluation of biopharmaceuticals with NHP often being the species of choice. For safety assessment of small molecules, NHP are used in case of a higher degree of metabolic similarity, to detect the highly specific immunotoxic side effects and to discriminate toxicity from efficacy of immunomodulatory drugs. Unlike for rodent immunotoxicity studies, standardized tests and protocols are generally less available for NHP. The immunotoxicity testing protocols described in the present chapter have been adapted for application to NHP samples. In principle, rodent protocols can be transferred to NHP. Fortunately, most of the immunotoxicity parameters delineated in the ICH S8 guideline can be applied to NHP specimens. Exceptions are the host resistance assay and the delayed type hypersensitivity test. Owing to the close structural and physiological similarity between NHP and human, human test kits or reagents are often well suited for application to NHP samples. For data evaluation it should be noted that no inbred strains of NHP are available, resulting in a large inter-animal variability for most immunotoxicity assay results. The experimental protocols and reagents described in this chapter were developed specifically for the cynomolgus monkey (Macaca fascicularis), currently the most commonly used NHP species in toxicology. In many instances, these protocols will also be applicable to rhesus monkeys (M. mulatta) and potentially to other Old World macaques. For the marmoset (Callithrix jacchus), a New World monkey also used in toxicology, the choice of available immunotoxicity testing protocols is much reduced when compared to macaques.

Loss of S100A9 (MRP14) results in reduced interleukin-8-induced CD11b surface expression, a polarized microfilament system, and diminished responsiveness to chemoattractants in vitro.

The S100A9 (MRP14) protein is abundantly expressed in myeloid cells and has been associated with various inflammatory diseases. The S100A9-deficient mice described here were viable, fertile, and generally of healthy appearance. The myelopoietic potential of the S100A9-null bone marrow was normal. S100A8, the heterodimerization partner of S100A9 was not detectable in peripheral blood cells, suggesting that even a deficiency in both S100A8 and S100A9 proteins was compatible with viable and mature neutrophils. Surprisingly, the invasion of S100A9-deficient leukocytes into the peritoneum and into the skin in vivo was indistinguishable from that in wild-type mice. However, stimulation of S100A9-deficient neutrophils with interleukin-8 in vitro failed to provoke an up-regulation of CD11b. Migration upon a chemotactic stimulus through an endothelial monolayer was markedly diminished in S100A9-deficient neutrophils. Attenuated chemokinesis of the S100A9-deficient neutrophils was observed by using a three-dimensional collagen matrix migration assay. The altered migratory behavior was associated with a microfilament system that was highly polarized in unstimulated S100A9-deficient neutrophils. Our data suggest that loss of the calcium-binding S100A9 protein reduces the responsiveness of the neutrophils upon chemoattractant stimuli at least in vitro. Alternative pathways for neutrophil emigration may be responsible for the lack of any effect in the two in vivo models we have investigated so far.

Only the soluble form of the scavenger receptor CD163 acts inhibitory on phorbol ester-activated T-lymphocytes, whereas membrane-bound protein has no effect.

The extracellular moiety of the hemoglobin/haptoglobin scavenger receptor CD163 (RM3/1 antigen) can be shed from monocytes and is a normal plasma component. We found that in a dose-dependent manner soluble CD163 induces a decrease in CD69 expression, a reduced [(3)H]thymidine uptake and a down-regulated matrix metalloproteinase-9 RNA expression in phorbol myristate acetate-stimulated T-cells. Co-culturing T-cells on transgenic fibroblasts, expressing membrane-bound CD163, yielded no differences compared to culture on non-transfected cells. We conclude that CD163 has at least two distinct functions: the clearance of hemoglobin in its cell-bound form and participation in anti-inflammation as a soluble factor, exhibiting cytokine-like functions.

Adaptation of primate cell-adapted hepatitis A virus strain HM175 to growth in guinea pig cells is independent of mutations in the 5' nontranslated region.

Previous studies of hepatitis A virus (HAV) genotypes after adaptation of wild-type virus to growth in cell cultures of primate origin identified determinants for growth in cell culture in the viral 2B and 2C protein-coding regions of the genome and demonstrated that an increased growth efficiency in a particular cell line was achieved by subsequent mutations in the 5' nontranslated region (5'NTR). The results reported in this study demonstrate that the passage of HAV adapted to primate BS-C-1 cells in guinea pig cells resulted in increased growth efficiency in the rodent cells and decreased growth efficiency in BS-C-1 cells. This adaptation occurred without mutation in the 5'NTR, but the viral 2B and 2C proteins seem to play a role during adaptation to the new environment, as one mutation occurred in each protein. Although the data presented here do not clearly identify which region of the viral genome underwent mutations to improve the interaction of the viruses with guinea pig proteins, they do confirm that the 5'NTR is not the only region responsible for providing host cell-specific information.