Non-Clinical Safety Evaluation of Exosomes Derived from Human Umbilical Cord Mesenchymal Stem Cells in Cynomolgus Monkeys.

Purpose: In recent years, exosomes have been proved to be used to treat many diseases. However, due to the lack of uniform quality control standards for exosomes, the safety of exosomes is still a problem to be solved, especially now more and more exosomes are used in clinical trials, and its non-clinical safety evaluation is particularly important. However, there is no safety evaluation standard for exosomes at present. Therefore, this study will refer to the evaluation criteria of therapeutic biological products, adopt non-human primates to evaluate the non-clinical safety of human umbilical cord mesenchymal stem cell exosomes from the general pharmacology and immunotoxicity, aiming at establishing a safety evaluation system of exosomes and providing reference for the clinical application of exosomes in the future. Methods: 3.85 × 1012 exosomes derived from human umbilical cord mesenchymal stem cells were injected into cynomolgus monkeys intravenously. The changes of general clinical conditions, hematology, immunoglobulin, Th1/Th2 cytokines, T lymphocytes and B lymphocytes, and immune organs were observed before and within 14 days after injection. Results: The results showed that exosomes did not have obvious pathological effects on the general clinical conditions, blood, coagulation function, organ coefficient, immunoglobulin, Th1/Th2 cytokines, lymphocytes, major organs, and major immune organs (spleen, thymus, bone marrow) of cynomolgus monkeys. However, the number of granulocyte-macrophage colonies in exosomes group was significantly higher than that in control group. Conclusion: To sum up, the general pharmacological results and immunotoxicity results showed that the injection of 3.85 × 1012 exosomes may have no obvious adverse reactions to cynomolgus monkeys. This dose of exosomes is relatively safe for treatment, which provides basis research for non-clinical safety evaluation of exosomes and provides reliable research basis for future clinical application of exosomes.

Discovery of a potent, selective, and tumor-suppressing antibody antagonist of adenosine A2A receptor.

New immune checkpoints are emerging in a bid to improve response rates to immunotherapeutic drugs. The adenosine A2A receptor (A2AR) has been proposed as a target for immunotherapeutic development due to its participation in immunosuppression of the tumor microenvironment. Blockade of A2AR could restore tumor immunity and, consequently, improve patient outcomes. Here, we describe the discovery of a potent, selective, and tumor-suppressing antibody antagonist of human A2AR (hA2AR) by phage display. We constructed and screened four single-chain variable fragment (scFv) libraries-two synthetic and two immunized-against hA2AR and antagonist-stabilized hA2AR. After biopanning and ELISA screening, scFv hits were reformatted to human IgG and triaged in a series of cellular binding and functional assays to identify a lead candidate. Lead candidate TB206-001 displayed nanomolar binding of hA2AR-overexpressing HEK293 cells; cross-reactivity with mouse and cynomolgus A2AR but not human A1, A2B, or A3 receptors; functional antagonism of hA2AR in hA2AR-overexpressing HEK293 cells and peripheral blood mononuclear cells (PBMCs); and tumor-suppressing activity in colon tumor-bearing HuCD34-NCG mice. Given its therapeutic properties, TB206-001 is a good candidate for incorporation into next-generation bispecific immunotherapeutics.

Preclinical characterization of a novel investigational monoclonal antibody CM313 with potent CD38-positive cell killing activity.

Introduction: CM313 is currently under clinical investigation for treatments of multiple myeloma, systemic lupus erythematosus, and immune thrombocytopenia. We aimed to report the preclinical profile of the novel therapeutic anti-CD38 monoclonal antibody (mAb) CM313, with an emphasis on the difference with other CD38-targeting mAb. Methods: The binding of CM313 to CD38 recombinant protein across species was assessed using ELISA. The binding of CM313 to CD38-positive (CD38+) cells was detected using flow cytometry assays. CM313-induced complement-dependent cytotoxicity (CDC), antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP) and apoptosis on different CD38+ cells were assessed by LDH release assays or flow cytometry assays. The effect of CM313 on CD38 enzymatic activity was measured using fluorescence spectroscopy. CM313 immunotoxicity in human blood was assessed using flow cytometry assays, ELISA, and LDH release assays. Anti-tumor activity of CM313 was assessed in multiple mouse xenograft models. Safety profile of CM313 were evaluated in cynomolgus monkeys and human CD38 transgenic (B-hCD38) mice. Results: There exist unique sequences at complementarity-determining regions (CDR) of CM313, which facilitates its affinity to CD38 is consistently higher across a spectrum of CD38+ cell lines than daratumumab. In vitro studies showed that CM313 induces comparable killing activity than daratumumab, including ADCC, CDC, ADCP, apoptosis induced by Fc-mediated cross-linking, and effectively inhibited the enzymatic activity of CD38. However, CM313 showed more potent CDC than isatuximab. In vivo, CM313 dose-dependently inhibited xenograft tumor growth, both as a monotherapy and in combination with dexamethasone or lenalidomide. Furthermore, CM313 was well tolerated with no drug-related clinical signs or off-target risks, as evidenced by 4-week repeat-dose toxicology studies in cynomolgus monkeys and B-hCD38 mice, with the later study showing no observed adverse effect level (NOAEL) of 300mg/kg once weekly. Discussion: CM313 is a novel investigational humanized mAb with a distinct CDR sequence, showing comparable killing effects with daratumumab and stronger CDC activity than isatuximab, which supports its clinical development.

Graft cell expansion from hiPSC-RPE strip after transplantation in primate eyes with or without RPE damage.

Clinical studies using suspensions or sheets of human pluripotent cell-derived retinal pigment epithelial cells (hiPSC-RPE) have been conducted globally for diseases such as age-related macular degeneration. Despite being minimally invasive, cell suspension transplantation faces challenges in targeted cell delivery and frequent cell leakage. Conversely, although the RPE sheet ensures targeted delivery with correct cell polarity, it requires invasive surgery, and graft preparation is time-consuming. We previously reported hiPSC-RPE strips as a form of quick cell aggregate that allows for reliable cell delivery to the target area with minimal invasiveness. In this study, we used a microsecond pulse laser to create a local RPE ablation model in cynomolgus monkey eyes. The hiPSC-RPE strips were transplanted into the RPE-ablated and intact sites. The hiPSC-RPE strip stably survived in all transplanted monkey eyes. The expansion area of the RPE from the engrafted strip was larger at the RPE injury site than at the intact site with no tumorigenic growth. Histological observation showed a monolayer expansion of the transplanted RPE cells with the expression of MERTK apically and collagen type 4 basally. The hiPSC-RPE strip is considered a beneficial transplantation option for RPE cell therapy.

Striking the Balance with a PD-L1×4-1BB Bispecific Antibody.

Antibody-based immune checkpoint blockade therapy has revolutionized the field of cancer immunotherapy, yet its efficacy remains limited in immunologically cold tumors. Combining checkpoint inhibitors with costimulatory agonists improves tumoricidal activity of T cells but also can lead to off-target hepatotoxicity. Although bispecific antibodies confer tumor selectivity to alleviate undesirable adverse effects, toxicity concerns persist with increased dosing. In this issue of Cancer Research, Yuwen and colleagues introduce ATG-101, a tetravalent PD-L1×4-1BB bispecific antibody with high programmed death ligand 1 (PD-L1) affinity and low 4-1BB affinity, aiming to mitigate hepatotoxicity. ATG-101 demonstrates PD-L1-dependent 4-1BB activation, leading to selective T-cell activation within the tumor microenvironment. ATG-101 exhibits potent antitumor activity, even in large, immunologically cold, and monotherapy-resistant tumor models. Single-cell RNA sequencing reveals significant shifts of immune cell populations in the tumor microenvironment from protumor to antitumor phenotypes following ATG-101 treatment. In cynomolgus monkeys, no serious cytokine storm and hepatotoxicity are observed after ATG-101 treatment, indicating a broad therapeutic window for ATG-101 in cancer treatment. This study highlights the potential of tetravalent bispecific antibodies in cancer immunotherapy, with implications for various antibody-based treatment modalities across different fields. See related article by Yuwen et al., p. 1680.

Preclinical efficacy and pharmacokinetics of an RNA-encoded T cell-engaging bispecific antibody targeting human claudin 6.

We present the preclinical pharmacology of BNT142, a lipid nanoparticle (LNP)-formulated RNA (RNA-LNP) encoding a T cell-engaging bispecific antibody that monovalently binds the T cell marker CD3 and bivalently binds claudin 6 (CLDN6), an oncofetal antigen that is absent from normal adult tissue but expressed on various solid tumors. Upon BNT142 RNA-LNP delivery in cell culture, mice, and cynomolgus monkeys, RNA is translated, followed by self-assembly into and secretion of the functional bispecific antibody RiboMab02.1. In vitro, RiboMab02.1 mediated CLDN6 target cell-specific activation and proliferation of T cells, and potent target cell killing. In mice and cynomolgus monkeys, intravenously administered BNT142 RNA-LNP maintained therapeutic serum concentrations of the encoded antibody. Concentrations of RNA-encoded RiboMab02.1 were maintained longer in circulation in mice than concentrations of directly injected, sequence-identical protein. Weekly injections of mice with BNT142 RNA-LNP in the 0.1- to 1-µg dose range were sufficient to eliminate CLDN6-positive subcutaneous human xenograft tumors and increase survival over controls. Tumor regression was associated with an influx of T cells and depletion of CLDN6-positive cells. BNT142 induced only transient and low cytokine production in CLDN6-positive tumor-bearing mice humanized with peripheral blood mononuclear cells (PBMCs). No signs of adverse effects from BNT142 RNA-LNP administration were observed in mice or cynomolgus monkeys. On the basis of these and other findings, a phase 1/2 first-in-human clinical trial has been initiated to assess the safety and preliminary efficacy of BNT142 RNA-LNP in patients with CLDN6-positive advanced solid tumors (NCT05262530).

Bio-distribution and toxicity potential of human umbilical cord mesenchymal stem cells in cynomolgus monkeys.

Mesenchymal stem cells (MSCs) have demonstrated promising advantages in the therapies of many diseases, while its multi-directional differentiation potential and immunotoxicity are the major concerns hindered their clinical translation. In this study, human umbilical Mesenchymal stem cell (hUC-MSCs) were labeled with a near-infrared fluorescent dye DiR before infused into cynomolgus monkeys, and the amount of hUC-MSCs in the peripheral blood were dynamically estimated from 5 min to 28 days post a single administration at 3 × 106 cells/kg and 2 × 107 cells/kg intravenously. As results, some hUC-MSCs distributed to the whole body within 5 min, while most of the cells accumulate in the lungs along with the systemic blood circulation, and subsequently released into the blood. The toxicity potentials of hUC-MSCs were investigated in another 30 cynomolgus monkeys, and the cells were repeatedly administrated at doses of 3 × 106 cells/kg and 2 × 107 cells/kg for 5 times on a weekly basis, with a recovery period of 1 months. hUC-MSCs showed no obvious toxic effects in cynomolgus monkeys, except xenogeneic immune rejection to human stem cells. Low levels of the hUC-MSC gene were detected in the peripheral blood of a few animals administered 2 × 107 cells/kg at 30 min subsequent to the first and last administration, and there was no significant difference in the copy number of the hUC-MSC gene in the blood samples compared with the first and last administration, indicating that the hUC-MSC was not significantly amplified in vivo, and it its safe in non-human primates. Our study for the first time verified the safety of long-term use of hUC-MSCs in primates. We have pioneered a technology for the real-time detection of hUC-MSCs in peripheral blood and provide dynamicand rapid monitoring of the distribution characteristics of hUC-MSCs in vivo. Here, we provide data supporting the application of such products for clinical treatment and the application of stem cells in major refractory diseases and regenerative medicine.

Pharmacokinetics and safety of LEAD-452, an EGFR-specific 4-1BB-agonistic trimerbody in non-human primates.

LEAD-452 is a humanized bispecific EGFR-targeted 4-1BB-agonistic trimerbody with a unique trimeric configuration compared to other 4-1BB-specific antibodies that are currently in development. Indeed, enhanced tumor-specific costimulation and very remarkable safety and efficacy profiles have been observed in mouse models. Here, we conducted for the first time a preclinical pharmacokinetic and toxicity study in non-human primates (NHP) (Macaca fascicularis). LEAD-452 exhibits comparable binding affinity for human and macaque targets, indicating its pharmacological significance for safety testing across species. The NHP were administered LEAD-452 in a series of ascending doses, ranging from 0.1 mg/kg to 10 mg/kg, and repeated doses up to 20 mg/kg. The administration of LEAD-452 was found to be clinically well tolerated, with no major related adverse effects observed. Furthermore, there have been no reported cases of liver toxicity, thrombocytopenia, and neutropenia, which are commonly associated with treatments using conventional anti-4-1BB IgG-based antibodies. In addition, neither IgM nor IgG-based anti-drug antibodies were detected in serum samples from NHP during the study, regardless of the dose of LEAD-452 administered. These results support the clinical development of LEAD-452 for the treatment of solid tumors.

Targeting CEACAM5-positive solid tumors using NILK-2401, a novel CEACAM5xCD47 κλ bispecific antibody.

Background: Blocking the CD47 "don't eat me"-signal on tumor cells with monoclonal antibodies or fusion proteins has shown limited clinical activity in hematologic malignancies and solid tumors thus far. Main side effects are associated with non-tumor targeted binding to CD47 particularly on blood cells. Methods: We present here the generation and preclinical development of NILK-2401, a CEACAM5×CD47 bispecific antibody (BsAb) composed of a common heavy chain and two different light chains, one kappa and one lambda, determining specificity (so-called κλ body format). Results: NILK-2401 is a fully human BsAb binding the CEACAM5 N-terminal domain on tumor cells by its lambda light chain arm with an affinity of ≈4 nM and CD47 with its kappa chain arm with an intendedly low affinity of ≈500 nM to enabling tumor-specific blockade of the CD47-SIRPα interaction. For increased activity, NILK-2401 features a functional IgG1 Fc-part. NILK-2401 eliminates CEACAM5-positive tumor cell lines (3/3 colorectal, 2/2 gastric, 2/2 lung) with EC50 for antibody-dependent cellular phagocytosis and antibody-dependent cellular cytotoxicity ranging from 0.38 to 25.84 nM and 0.04 to 0.25 nM, respectively. NILK-2401 binds neither CD47-positive/CEACAM5-negative cell lines nor primary epithelial cells. No erythrophagocytosis or platelet activation is observed. Quantification of the pre-existing NILK-2401-reactive T-cell repertoire in the blood of 14 healthy donors with diverse HLA molecules shows a low immunogenic potential. In vivo, NILK-2401 significantly delayed tumor growth in a NOD-SCID colon cancer model and a syngeneic mouse model using human CD47/human SIRPα transgenic mice and prolonged survival. In cynomolgus monkeys, single doses of 0.5 and 20 mg/kg were well tolerated; PK linked to anti-CD47 and Fc-binding seemed to be more than dose-proportional for Cmax and AUC0-inf. Data were validated in human FcRn TG32 mice. Combination of a CEACAM5-targeting T-cell engager (NILK-2301) with NILK-2401 can either boost NILK-2301 activity (Emax) up to 2.5-fold or allows reaching equal NILK-2301 activity at >600-fold (LS174T) to >3,000-fold (MKN-45) lower doses. Conclusion: NILK-2401 combines promising preclinical activity with limited potential side effects due to the tumor-targeted blockade of CD47 and low immunogenicity and is planned to enter clinical testing.

Preliminary investigation into long-term stress by isolated captivity-related changes of reproduction hormones in Cynomolgus monkey.

BACKGROUND: Stress profoundly affects physical and emotional well-being, extending its physiological influence to the female menstrual cycle, impeding the hypothalamus-pituitary-gonadal (HPG) axis, and affecting fertility by suppressing sex-stimulating hormones. METHODS: In this study, we meticulously analyzed menstrual cycles and corresponding hormonal fluctuations in three female Cynomolgus monkeys. RESULTS: The preliminary findings indicated lower-than-normal levels of cortisol, follicle-stimulating hormone (FSH), and estradiol. Anovulatory bleeding occurred in one monkey, which could be linked to stress. In contrast to cortisol, alkaline phosphatase (ALP), which is correlated to cortisol levels, was consistently elevated in menstruating monkeys, suggesting its potential as a stress indicator. The non-menstruating group exhibited stress-related weight loss, emphasizing the observed ALP trends. CONCLUSIONS: Non-menstruating monkeys may experience more stress than menstruating monkeys. The implications of this study extend beyond the confines of primate studies and offer a valuable method for enhancing the welfare of female Cynomolgus monkeys.

A digoxin derivative that potently reduces intraocular pressure: efficacy and mechanism of action in different animal models.

Glaucoma is a blinding disease. Reduction of intraocular pressure (IOP) is the mainstay of treatment, but current drugs show side effects or become progressively ineffective, highlighting the need for novel compounds. We have synthesized a family of perhydro-1,4-oxazepine derivatives of digoxin, the selective inhibitor of Na,K-ATPase. The cyclobutyl derivative (DcB) displays strong selectivity for the human α2 isoform and potently reduces IOP in rabbits. These observations appeared consistent with a hypothesis that in ciliary epithelium DcB inhibits the α2 isoform of Na,K-ATPase, which is expressed strongly in nonpigmented cells, reducing aqueous humor (AH) inflow. This paper extends assessment of efficacy and mechanism of action of DcB using an ocular hypertensive nonhuman primate model (OHT-NHP) (Macaca fascicularis). In OHT-NHP, DcB potently lowers IOP, in both acute (24 h) and extended (7-10 days) settings, accompanied by increased aqueous humor flow rate (AFR). By contrast, ocular normotensive animals (ONT-NHP) are poorly responsive to DcB, if at all. The mechanism of action of DcB has been analyzed using isolated porcine ciliary epithelium and perfused enucleated eyes to study AH inflow and AH outflow facility, respectively. 1) DcB significantly stimulates AH inflow although prior addition of 8-Br-cAMP, which raises AH inflow, precludes additional effects of DcB. 2) DcB significantly increases AH outflow facility via the trabecular meshwork (TM). Taken together, the data indicate that the original hypothesis on the mechanism of action must be revised. In the OHT-NHP, and presumably other species, DcB lowers IOP by increasing AH outflow facility rather than by decreasing AH inflow.NEW & NOTEWORTHY When applied topically, a cyclobutyl derivative of digoxin (DcB) potently reduces intraocular pressure in an ocular hypertensive nonhuman primate model (Macaca fascicularis), associated with increased aqueous humor (AH) flow rate (AFR). The mechanism of action of DcB involves increased AH outflow facility as detected in enucleated perfused porcine eyes and, in parallel, increased (AH) inflow as detected in isolated porcine ciliary epithelium. DcB might have potential as a drug for the treatment of open-angle human glaucoma.

Nonclinical Investigation of Cytokine Mitigation Strategies for T-cell-Engaging Bispecifics in the Cynomolgus Macaque.

SUMMARY: T-cell-directed cancer therapies such as T-cell-engaging bispecifics (TCBs) are commonly associated with cytokine release syndrome and associated clinical signs that can limit their tolerability and therapeutic benefit. Strategies for reducing cytokine release are therefore needed. Here, we report on studies performed in cynomolgus monkeys to test different approaches for mitigating cytokine release with TCBs. A "priming dose" as well as subcutaneous dosing reduced cytokine release compared with intravenous dosing but did not affect the intended T-cell response to the bispecific. As another strategy, cytokines or cytokine responses were blocked with an anti-IL-6 antibody, dexamethasone, or a JAK1/TYK2-selective inhibitor, and the effects on toxicity as well as T-cell responses to a TCB were evaluated. The JAK1/TYK2 inhibitor and dexamethasone prevented CRS-associated clinical signs on the day of TCB administration, but the anti-IL-6 had little effect. All interventions allowed for functional T-cell responses and expected damage to target-bearing tissues, but the JAK1/TYK2 inhibitor prevented the upregulation of activation markers on T cells, suggesting the potential for suppression of T-cell responses. Our results suggest that short-term prophylactic dexamethasone treatment may be an effective option for blocking cytokine responses without affecting desired T-cell responses to TCBs.

DB-1310, an ADC comprised of a novel anti-HER3 antibody conjugated to a DNA topoisomerase I inhibitor, is highly effective for the treatment of HER3-positive solid tumors.

BACKGROUND: HER3 (ErbB3), a member of the human epidermal growth factor receptor family, is frequently overexpressed in various cancers. Multiple HER3-targeting antibodies and antibody-drug conjugates (ADCs) were developed for the solid tumor treatment, however none of HER3-targeting agent has been approved for tumor therapy yet. We developed DB-1310, a HER3 ADC composed of a novel humanized anti-HER3 monoclonal antibody covalently linked to a proprietary DNA topoisomerase I inhibitor payload (P1021), and evaluate the efficacy and safety of DB-1310 in preclinical models. METHODS: The binding of DB-1310 to Her3 and other HER families were measured by ELISA and SPR. The competition of binding epitope for DB-1310 and patritumab was tested by FACS. The sensitivity of breast, lung, prostate and colon cancer cell lines to DB-1310 was evaluated by in vitro cell killing assay. In vivo growth inhibition study evaluated the sensitivity of DB-1310 to Her3 + breast, lung, colon and prostate cancer xenograft models. The safety profile was also measured in cynomolgus monkey. RESULTS: DB-1310 binds HER3 via a novel epitope with high affinity and internalization capacity. In vitro, DB-1310 exhibited cytotoxicity in numerous HER3 + breast, lung, prostate and colon cancer cell lines. In vivo studies in HER3 + HCC1569 breast cancer, NCI-H441 lung cancer and Colo205 colon cancer xenograft models showed DB-1310 to have dose-dependent tumoricidal activity. Tumor suppression was also observed in HER3 + non-small cell lung cancer (NSCLC) and prostate cancer patient-derived xenograft (PDX) models. Moreover, DB-1310 showed stronger tumor growth-inhibitory activity than patritumab deruxtecan (HER3-DXd), which is another HER3 ADC in clinical development at the same dose. The tumor-suppressive activity of DB-1310 synergized with that of EGFR tyrosine kinase inhibitor, osimertinib, and exerted efficacy also in osimertinib-resistant PDX model. The preclinical assessment of safety in cynomolgus monkeys further revealed DB-1310 to have a good safety profile with a highest non severely toxic dose (HNSTD) of 45 mg/kg. CONCLUSIONS: These finding demonstrated that DB-1310 exerted potent antitumor activities against HER3 + tumors in in vitro and in vivo models, and showed acceptable safety profiles in nonclinical species. Therefore, DB-1310 may be effective for the clinical treatment of HER3 + solid tumors.

DR30318, a novel tri-specific T cell engager for Claudin 18.2 positive cancers immunotherapy.

BACKGROUND: Claudin 18.2 (CLDN18.2) is a highly anticipated target for solid tumor therapy, especially in advanced gastric carcinoma and pancreatic carcinoma. The T cell engager targeting CLDN18.2 represents a compelling strategy for enhancing anti-cancer efficacy. METHODS: Based on the in-house screened anti-CLDN18.2 VHH, we have developed a novel tri-specific T cell engager targeting CLDN18.2 for gastric and pancreatic cancer immunotherapy. This tri-specific antibody was designed with binding to CLDN18.2, human serum albumin (HSA) and CD3 on T cells. RESULTS: The DR30318 demonstrated binding affinity to CLDN18.2, HSA and CD3, and exhibited T cell-dependent cellular cytotoxicity (TDCC) activity in vitro. Pharmacokinetic analysis revealed a half-life of 22.2-28.6 h in rodents and 41.8 h in cynomolgus monkeys, respectively. The administration of DR30318 resulted in a slight increase in the levels of IL-6 and C-reactive protein (CRP) in cynomolgus monkeys. Furthermore, after incubation with human PBMCs and CLDN18.2 expressing cells, DR30318 induced TDCC activity and the production of interleukin-6 (IL-6) and interferon-gamma (IFN-γ). Notably, DR30318 demonstrated significant tumor suppression effects on gastric cancer xenograft models NUGC4/hCLDN18.2 and pancreatic cancer xenograft model BxPC3/hCLDN18.2 without affecting the body weight of mice.

Preclinical and translational pharmacology of afucosylated anti-CCR8 antibody for depletion of tumour-infiltrating regulatory T cells.

BACKGROUND AND PURPOSE: RO7502175 is an afucosylated antibody designed to eliminate C-C motif chemokine receptor 8 (CCR8)+ Treg cells in the tumour microenvironment through enhanced antibody-dependent cellular cytotoxicity (ADCC). EXPERIMENTAL APPROACH: We report findings from preclinical studies characterizing pharmacology, pharmacokinetics (PK)/pharmacodynamics (PD) and safety profile of RO7502175 and discuss the translational PK/PD approach used to inform first-in-human (FiH) dosing strategy and clinical development in solid tumour indications. KEY RESULTS: RO7502175 demonstrated selective ADCC against human CCR8+ Treg cells from dissociated tumours in vitro. In cynomolgus monkeys, RO7502175 exhibited a biphasic concentration-time profile consistent with immunoglobulin G1 (IgG1) antibodies, reduced CCR8+ Treg cells in the blood, induced minimal and transient cytokine secretion, and was well tolerated with a no-observed-adverse-effect level (NOAEL) of 100 mg·kg-1. Moreover, RO7502175 caused minimal cytokine release from peripheral blood mononuclear cells (PBMCs) in vitro. A quantitative model was developed to capture surrogate anti-murine CCR8 antibody PK/PD and tumour dynamics in mice and RO7502175 PK/PD in cynomolgus monkeys. Subsequently, the model was used to project RO7502175 human PK and receptor occupancy (RO) in patients. Because traditional approaches resulted in a low FiH dose for this molecule, even with its superior preclinical safety profile, an integrated approach based on the totality of preclinical data and modelling insights was used for starting dose selection. CONCLUSION AND IMPLICATIONS: This work demonstrates a translational research strategy for collecting and utilizing relevant nonclinical data, developing a mechanistic PK/PD model and using a comprehensive approach to inform clinical study design for RO7502175.

Characterization of AST-001 non-clinical pharmacokinetics: A novel selective AKR1C3-activated prodrug in mice, rats, and cynomolgus monkeys.

AST-001 is a chemically synthesized inactive nitrogen mustard prodrug that is selectively cleaved to a cytotoxic aziridine (AST-2660) via aldo-keto reductase family 1 member C3 (AKR1C3). The purpose of this study was to investigate the pharmacokinetics and tissue distribution of the prodrug, AST-001, and its active metabolite, AST-2660, in mice, rats, and monkeys. After single and once daily intravenous bolus doses of 1.5, 4.5, and 13.5 mg/kg AST-001 to Sprague-Dawley rats and once daily 1 h intravenous infusions of 0.5, 1.5, and 4.5 mg/kg AST-001 to cynomolgus monkeys, AST-001 exhibited dose-dependent pharmacokinetics and reached peak plasma levels at the end of the infusion. No significant accumulation and gender differences were observed after 7 days of repeated dosing. In rats, the half-life of AST-001 was dose independent and ranged from 4.89 to 5.75 h. In cynomolgus monkeys, the half-life of AST-001 was from 1.66 to 5.56 h and increased with dose. In tissue distribution studies conducted in Sprague-Dawley rats and in liver cancer PDX models in female athymic nude mice implanted with LI6643 or LI6280 HepG2-GFP tumor fragments, AST-001 was extensively distributed to selected tissues. Following a single intravenous dose, AST-001 was not excreted primarily as the prodrug, AST-001 or the metabolite AST-2660 in the urine, feces, and bile. A comprehensive analysis of the preclinical data and inter-species allometric scaling were used to estimate the pharmacokinetic parameters of AST-001 in humans and led to the recommendation of a starting dose of 5 mg/m2 in the first-in-human dose escalation study.

Oral administration of obeldesivir protects nonhuman primates against Sudan ebolavirus.

Obeldesivir (ODV, GS-5245) is an orally administered prodrug of the parent nucleoside of remdesivir (RDV) and is presently in phase 3 trials for COVID-19 treatment. In this work, we show that ODV and its circulating parent nucleoside metabolite, GS-441524, have similar in vitro antiviral activity against filoviruses, including Marburg virus, Ebola virus, and Sudan virus (SUDV). We also report that once-daily oral ODV treatment of cynomolgus monkeys for 10 days beginning 24 hours after SUDV exposure confers 100% protection against lethal infection. Transcriptomics data show that ODV treatment delayed the onset of inflammation and correlated with antigen presentation and lymphocyte activation. Our results offer promise for the further development of ODV to control outbreaks of filovirus disease more rapidly.

Characterization of preclinical Alzheimer's disease model: spontaneous type 2 diabetic cynomolgus monkeys with systemic pro-inflammation, positive biomarkers and developing AD-like pathology.

BACKGROUND: The key to the prevention and treatment of Alzheimer's disease (AD) is to be able to predict and diagnose AD at the preclinical or early stage, but the lack of a preclinical model of AD is the critical factor that causes this problem to remain unresolved. METHODS: We assessed 18 monkeys in vivo evaluation of pro-inflammatory cytokines and AD pathological biomarkers (n = 9 / type 2 diabetic mellitus (T2DM) group, age 20, fasting plasma glucose (FPG) ≥ 100 mg/dL, and n = 9 / negative control (NC) group, age 17, FPG < 100 mg/dL). Levels of pro-inflammatory cytokines and AD pathological biomarkers was measured by ELISA and Simoa Technology, respectively. 9 monkeys evaluated ex vivo for AD-like pathology (n = 6 / T2DM group, age 22.17, FPG ≥ 126 mg/dL, and n = 3 / NC group, age 14.67, FPG < 100 mg/dL). To evaluate the pathological features of AD in the brains of T2DM monkeys, we assessed the levels of Aß, phospho-tau, and neuroinflammation using immunohistochemistry, which further confirmed the deposition of Aß plaques by Bielschowsky's silver, Congo red, and Thioflavin S staining. Synaptic damage and neurodegeneration were assessed by immunofluorescence. RESULTS: We found not only increased levels of pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α) in peripheral blood (PB) and brain of T2DM monkeys but also changes in PB of AD pathological biomarkers such as decreased ß-amyloid (Aß) 42 and Aß40 levels. Most notably, we observed AD-like pathological features in the brain of T2DM monkeys, including Aß plaque deposition, p-tau from neuropil thread to pre-neurofibrillary tangles (NFTs), and even the appearance of extracellular NFT. Microglia were activated from a resting state to an amoeboid. Astrocytes showed marked hypertrophy and an increased number of cell bodies and protrusions. Finally, we observed impairment of the postsynaptic membrane but no neurodegeneration or neuronal death. CONCLUSIONS: Overall, T2DM monkeys showed elevated levels of peripheral and intracerebral inflammation, positive AD biomarkers in body fluids, and developing AD-like pathology in the brain, including Aß and tau pathology, glial cell activation, and partial synaptic damage, but no neuronal degeneration or death as compared to the healthy normal group. Hereby, we consider the T2DM monkeys with elevation of the peripheral pro-inflammatory factors and positive AD biomarkers can be potentially regarded as a preclinical AD model.

Transgene-Free Cynomolgus Monkey iPSCs Generated under Chemically Defined Conditions.

Non-human primates (NHPs) are pivotal animal models for translating novel cell replacement therapies into clinical applications, including validating the safety and efficacy of induced pluripotent stem cell (iPSC)-derived products. Preclinical development and the testing of cell-based therapies ideally comprise xenogeneic (human stem cells into NHPs) and allogenic (NHP stem cells into NHPs) transplantation studies. For the allogeneic approach, it is necessary to generate NHP-iPSCs with generally equivalent quality to the human counterparts that will be used later on in patients. Here, we report the generation and characterization of transgene- and feeder-free cynomolgus monkey (Macaca fascicularis) iPSCs (Cyno-iPSCs). These novel cell lines have been generated according to a previously developed protocol for the generation of rhesus macaque, baboon, and human iPSC lines. Beyond their generation, we demonstrate the potential of the novel Cyno-iPSCs to differentiate into two clinically relevant cell types, i.e., cardiomyocytes and neurons. Overall, we provide a resource of novel iPSCs from the most frequently used NHP species in the regulatory testing of biologics and classical pharmaceutics to expand our panel of iPSC lines from NHP species with high relevance in preclinical testing and translational research.

Bronchioalveolar organoids: A preclinical tool to screen toxicity associated with antibody-drug conjugates.

Despite extensive preclinical testing, cancer therapeutics can result in unanticipated toxicity to non-tumor tissue in patients. These toxicities may pass undetected in preclinical experiments due to modeling limitations involving poor biomimicry of 2-dimensional in vitro cell cultures and due to lack of interspecies translatability in in vivo studies. Instead, primary cells can be grown into miniature 3-dimensional structures that recapitulate morphological and functional aspects of native tissue, termed "organoids." Here, human bronchioalveolar organoids grown from primary alveolar epithelial cells were employed to model lung epithelium and investigate off-target toxicities associated with antibody-drug conjugates (ADCs). ADCs with three different linker-payload combinations (mafodotin, vedotin, and deruxtecan) were tested in bronchioalveolar organoids generated from human, rat, and nonhuman primate lung cells. Organoids demonstrated antibody uptake and changes in viability in response to ADC exposure that model in vivo drug sensitivity. RNA sequencing identified inflammatory activation in bronchioalveolar cells in response to deruxtecan. Future studies will explore specific cell populations involved in interstitial lung disease and incorporate immune cells to the culture.