Preclinical Evaluation Of Efficacy Research Articles

Miniaturization of hiPSC-derived 3D neural cultures in stirred-tank bioreactors for parallelized preclinical assessment of rAAV.

Introduction: Engineered 3D models employing human induced pluripotent stem cell (hiPSC) derivatives have the potential to recapitulate the cell diversity and structure found in the human central nervous system (CNS). Therefore, these complex cellular systems offer promising human models to address the safety and potency of advanced therapy medicinal products (ATMPs), such as gene therapies. Specifically, recombinant adeno-associated viruses (rAAVs) are currently considered highly attractive for CNS gene therapy due to their broad tropism, low toxicity, and moderate immunogenicity. To accelerate the clinical translation of rAAVs, in-depth preclinical evaluation of efficacy and safety in a human setting is primordial. The integration of hiPSC-derived CNS models in rAAV development will require, amongst other factors, robust, small-scale, high-throughput culture platforms that can feed the preclinical trials. Methods: Herein, we pioneer the miniaturization and parallelization of a 200mL stirred-tank bioreactor-based 3D brain cell culture derived from hiPSCs. We demonstrate the applicability of the automated miniaturized Ambr® 15 Cell Culture system for the maintenance of hiPSC-derived neurospheroids (iNSpheroids), composed of neuronal and glial cells. Critical process parameters were optimized, namely, cell density and agitation mode. Results: Under optimized conditions, stable iNSpheroid cultures were attained in the microbioreactors for at least 15days, with high cell viability and astrocytic and neuronal phenotype maintenance. This culture setup allowed the parallelization of different rAAVs, in different multiplicity of infections (MOIs), to address rAAV-host interactions at a preclinical scale. The iNSpheroids were exposed to rAAV2- and rAAV9-eGFP in the microbioreactors. Transgene expression was detected 14days post-transduction, revealing different astrocyte/neuron tropism of the two serotypes. Discussion: We advocate that the iNSpheroid cultures in miniaturized bioreactors are reliable and reproducible screening tools for addressing rAAV transduction and tropism, compatible with preclinical demands.

Evaluation of preclinical efficacy of apremilast-loaded liquid crystalline nanoparticulate gel in amelioration of atopic dermatitis

Apremilast is a phosphodiesterase-4 inhibitor currently under investigation for managing atopic dermatitis, but it is associated with poor physicochemical properties, majorly affecting its bioavailability. To improve the topical delivery, we have encapsulated apremilast into the liquid crystalline nanoparticles and evaluated its preclinical efficacy against atopic dermatitis. The liquid crystalline nanoparticles were manufactured by the melt emulsification method followed by probe sonication. The prepared nanoparticles were evaluated for particle size, zeta potential, encapsulation efficiency and in vitro release. Further, the apremilast liquid crystalline nanoparticles were loaded into the gel base by magnetic stirring. The gel formulation was evaluated for viscosity, textural profile, drug content, ex vivo permeation, and retention in mice skin. The preclinical efficacy of optimized gel formulation was assessed in 2,4-dinitrochlorobenzene induced atopic dermatitis in mice model followed by histopathological examination of skin sections. The apremilast was successfully loaded into the liquid crystalline nanoparticles with an average particle size of 180 ± 0.45 nm and entrapment efficiency of 89.42 ± 4.27 %. The optimized nanoparticles were successfully loaded into gel base showing pseudoplastic shear thinning behaviour. In vivo preclinical efficacy of the optimized gel formulation revealed improved skin structure in comparison with negative control group. The histopathological examination of mice skin treated with optimized gel formulation resulted in decreased epidermal hyperplasia and intactness of outer keratinized epidermal layer with the inner layer. The outcomes of the apremilast-loaded liquid crystalline nanoparticulate gel demonstrated anti-atopic dermatitis potential.

Abstract 2815: Immunotherapy development landscape for bone metastasis - need of predictive preclinical efficacy evaluation for de-risking clinical development

Abstract Most cancer deaths are due to metastases, and bone metastases are challenge especially in breast and prostate cancer, being developed in 70-90% of advanced-stage patients. Bone metastases remain incurable causing high mortality, skeletal-related effects and decreased quality of life. Currently used immunotherapies are ineffective in bone metastases. This creates a need to improve understanding immune microenvironment in bone metastases, namely interactions between tumor, immune and bone cells according to the osteoimmuno-oncology (OIO) concept, and ultimately to develop immunotherapies that primarily target bone metastases. We used 1stOncology database, a cancer drug development resource to identify novel immunotherapies in development for breast and prostate cancer bone metastasis. Twenty-four immunotherapies that included evaluation of effects on bone metastasis were identified. Efficacy of only three of the identified therapies had been evaluated in preclinical bone metastasis models, one reason being that such models have not been commonly available. The use of clinically relevant and predictive preclinical bone metastasis models would significantly de-risk decision making when moving to clinical development in bone metastasizing cancers. To support predictive preclinical evaluation of immunotherapies for bone metastatic cancers, we describe a preclinical bone metastasis technology platform for evaluating efficacy of immunotherapies. The platform utilizes tumors growing in bone microenvironment, mimicking growth of bone metastases in patients, and generates tumor-induced bone effects in a cancer-type specific manner. Syngeneic and/or humanized mouse models with tumor and immune cells of the same species are needed for development of immunotherapies, allowing interactions of tumor and immune cells in the bone metastatic microenvironment to support mode-of-action studies. The platform is clinically predictive, as demonstrated with observed effects that align with clinical findings. As an example, anti-PD-1 antibody had no effects on breast and prostate cancer bone metastases, predicting recent clinical findings that demonstrate lack of efficacy in clinical prostate cancer trials. We conclude that tumor microenvironment in bone metastases has unique characteristics and is understudied as a potential primary cause of lack of efficacy of many immunotherapies, especially in breast and prostate cancer. It is prime time to focus on bone metastases by increasing understanding of the immune landscape in the bone tumor microenvironment according to the OIO concept. The biologically relevant and clinically predictive preclinical bone metastasis technology platform should be routinely used to study the mechanism-of-action and efficacy of therapies before entering clinical development in bone metastasizing cancers. Citation Format: Tiina E. Kähkönen, Jussi M. Halleen, Gary MacRitchie, Ronnie M. Andersson, Jenni Bernoulli. Immunotherapy development landscape for bone metastasis - need of predictive preclinical efficacy evaluation for de-risking clinical development [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2815.

Improving the predictive accuracy of efficacy evaluation using tumor orthotopic transplant and resection model.

Preclinical efficacy evaluation and tumor drug sensitivity analysis are two main applications of efficacy evaluation. Preclinical efficacy evaluation is to predict whether candidate drugs or therapies may improve patient outcomes in clinical trials. Tumor drug sensitivity analysis is an approach for the personalized evaluation and optimization of approved anti-cancer drugs and treatment regimens. Overall survival (OS) is the gold standard to evaluate the outcome of drugs or therapies in both clinical trials and clinical treatment. Many efficacy evaluation models, such as cell model, tumor cell-line transplant model, patient-derived tumor xenograft model, tumor organoid model, have been developed to assess the inhibitory effect of tested drugs or therapies on tumor growth. In fact, many treatments may also lead to malignant progression of tumors, such as chemotherapy, which can lead to metastasis. Therefore, tumor growth inhibition does not necessarily predict OS benefit. Whether it can prevent or inhibit tumor recurrence and metastasis is the key to whether drugs and therapies can improve patient outcomes. In this perspective, we summarize the current understanding of the pathological progression of tumor recurrence and metastasis, point out the shortcomings of existing tumor transplant models for simulating the clinical scenario of malignant progression of tumors, and propose five improved indicators for comprehensive efficacy evaluation to predict OS benefit using tumor orthotopic transplant and resection model. Improvement in the accuracy of efficacy evaluation will accelerate the development process of anti-cancer drugs or therapies, optimize treatment regimens to improve OS benefit, and reduce drug development and cancer treatment costs.

Artificial Bear Bile: A Novel Approach to Balancing Medical Requirements and Animal Welfare

Bear bile has been a valuable and effective medicinal material in traditional Chinese medicine (TCM) for over 13 centuries. However, the current practice of obtaining it through bear farming is under scrutiny for its adverse impact on bear welfare. Here, we present a new approach for creating artificial bear bile (ABB) as a high-quality and sustainable alternative to natural bear bile. This study addresses the scientific challenges of creating bear bile alternatives through interdisciplinary collaborations across various fields, including resources, chemistry, biology, medicine, pharmacology, and TCM. A comprehensive efficacy assessment system that bridges the gap between TCM and modern medical terminology has been established, allowing for the systematic screening of therapeutic constituents. Through the utilization of chemical synthesis and enzyme engineering technologies, our research has achieved the environmentally friendly, large-scale production of bear bile therapeutic compounds, as well as the optimization and recomposition of ABB formulations. The resulting ABB not only closely resembles natural bear bile in its composition but also offers advantages such as consistent product quality, availability of raw materials, and independence from threatened or wild resources. Comprehensive preclinical efficacy evaluations have demonstrated the equivalence of the therapeutic effects from ABB and those from commercially available drained bear bile (DBB). Furthermore, preclinical toxicological assessment and phase Ⅰ clinical trials show that the safety of ABB is on par with that of the currently used DBB. This innovative strategy can serve as a new research paradigm for developing alternatives for other endangered TCMs, thereby strengthening the integrity and sustainability of TCM.

Time-course transcriptome analysis of a double challenge bleomycin-induced lung fibrosis rat model uncovers ECM homoeostasis-related translationally relevant genes

BackgroundIdiopathic pulmonary fibrosis (IPF) is an irreversible disorder with a poor prognosis. The incomplete understanding of IPF pathogenesis and the lack of accurate animal models is limiting the development of...

Establishment of a primary renal lymphoma model and its clinical relevance.

Extranodal dissemination is an important feature of aggressive B-cell lymphoma. Owing to the lack of available animal models, the study on extranodal dissemination of lymphoma is greatly limited. Here, we identified a novel cell line, named MA-K, which originated from the Eμ-Myc;Cdkn2a-/- cell line, named MA-LN in this study. Compared to MA-LN, MA-K tended to disseminate in the kidney rather than the lymph nodes in the lymphoma transplantation model, resembling human primary renal lymphoma. The transcriptome analysis revealed that MA-K had undergone transcriptional evolution during the culture. The specialized transcriptional pattern analysis we proposed in this study identified that the FOXO1-BTG1-MYD88 pattern was formed in MA-K. Further analysis found that the translation pathway was the most enriched pathway in specially expressed genes (SEGs) in MA-K. Among the SEGs, three upregulated genes, RPLP2, RPS16, and MRPS16, and five downregulated genes, SSPN, CD52, ANKRD37, CCDC82, and VPREB3, in MA-K were identified as promising biomarkers to predict the clinical outcomes of human DLBCL. Moreover, the joint expression of the five-gene signature could effectively predict clinical outcomes of human DLBCL in three groups. These findings suggested that the MA-K cell line had strong clinical relevance with human aggressive B-cell lymphoma. Moreover, the MA-K primary renal lymphoma model, as a novel syngenetic mouse model, will be greatly useful for both basic research on lymphoma dissemination and preclinical efficacy evaluation of chemotherapy and immunotherapy.

Abstract 5206: A novel mouse model for preclinical efficacy evaluation of anti-CD3/GPRC5D bispecific antibodies

Abstract The FDA has granted Breakthrough Therapy Designation (BTD) for talquetamab, which targets both GPRC5D on multiple myeloma cells and CD3 on T-cells, for treating adult patients with relapsed or refractory multiple myeloma. Results showed that patients who received talquetamab experienced adverse events, including cytokine release syndrome (CRS), neutropenia, skin-related adverse events and dysgeusia. To allow preclinical in vivo evaluation of anti-human CD3/GPRC5D bispecific antibodies, we developed a BALB/c-hCD3EDG mouse model and a human GPRC5D-expressing A20 murine lymphoma cell line. The BALB/c-hCD3EDG cohort (6-8 weeks old) was subcutaneously inoculated with A20-hGPRC5D cells and then treated with anti-CD3/GPRC5D bispecific antibodies. As expected, anti-CD3/GPRC5D bispecific antibody treatment strongly inhibited the growth of A20-hGPRC5D tumors in BALB/c-hCD3EDG mice. To allow a comprehensive safety evaluation of anti-CD3/GPRC5D candidates, including the possibility of CRS and target organ toxicity, we engineered BALB/c-hCD3EDG mice that express hGPRC5D, denoted BALB/c-hCD3EDG/hGPRC5D. Human GPRC5D was detected in the liver, lung, thymus, adipose tissue, and thyroid. In vivo evaluation of anti-CD3/GPRC5D therapy in this mice is currently underway. In conclusion, BALB/c-hCD3EDG/hGPRC5D and BALB/c-hCD3EDG mice bearing A20-hGPRC5D tumors are suitable models for preclinical studies testing anti-CD3/GPRC5D bispecific antibodies. Citation Format: Xiaoliu Yang, Xinyuan Liang, Mingkun Zhang, Santi Suryani Chen, Zhiying Li, Erica Trujillo, Mark Wade Moore, Jing Zhao, Xiang Gao, Cunxiang Ju. A novel mouse model for preclinical efficacy evaluation of anti-CD3/GPRC5D bispecific antibodies. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5206.

Abstract 5198: Humanized mice for preclinical efficacy evaluation of drugs targeting GARP

Abstract Introduction: GARP (Glycoprotein-A repetitions predominant) is a cell surface receptor which is coded by Lrrc32 (Leucine rich repeat containing protein 32) and involved in the activation of TGF-beta. The expression of GARP has been widely found in various cells including Treg, activated B cells, mesenchymal stromal cells and many types of cancer cells. In the tumor microenvironment (TME), GARP from Treg promotes the growth of tumor via secretion of immune suppressive TGF-beta. Result: We established GARP humanized mouse model (hGARP) on C57BL/6 background in which the signal peptide and extracellular domain of mouse GARP (mGARP) was replaced by human GARP (hGARP). Similar expression level of hGARP on Treg cells in splenocytes from C57BL/6-hGARP mice was observed compared with mGARP in wildtype mice. After treating with anti-hGARP antibody, tumor growth was inhibited in the cohort engrafted with MC38 colorectal cancer cell line. Flow cytometry analysis of the tumor infiltrating lymphocytes revealed an abundant accumulation of hGARP on the Treg cells suggesting that blocking of hGARP in Treg cells contributed to the therapeutic efficiency. In addition, hGARP expression was also found on platelet cells from C57BL/6-hGARP mice, which is similar to human. After treating with anti-hGARP, we also found a significant reduction of platelet cells in C57BL/6-hGARP mice. In vivo assay suggested that the reduction of platelet cells from C57BL/6-hGARP mice correlated well with the binding of anti-hGARP. Conclusion: C57BL/6-hGARP is a well-established mouse model for the pre-clinical evaluation of both therapeutic effect and toxicity of anti-hGARP therapy. Citation Format: Xing Liu, Meirong Wu, Huiyi Wang, Weiwei Yu, Jianming Xu, Hongyan Sun, Cunxiang Ju, Hongyu Wang, Santi Suryani Chen, Zhiying Li, Mark Wade Moore, Jing Zhao, Xiang Gao. Humanized mice for preclinical efficacy evaluation of drugs targeting GARP. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5198.

Evaluation of preclinical efficacy of human umbilical cord mesenchymal stem cells in ankylosing spondylitis.

Umbilical cord mesenchymal stem cells (UCMSCs) have significant regenerative, tissue repair, and immunomodulatory properties that can help reduce inflammatory responses in patients with ankylosing spondylitis (AS). In this study, we used a combination of bovine proteoglycan and dimethyldioctadecylammonium (DDA) to establish a mouse model of proteoglycan-induced spondylitis (PGISp). To evaluate the therapeutic effects of UCMSCs, we treated PGISp mice with different doses of hUCMSCs via tail vein injection. At week 13, the PGISp mice exhibited thickened, erythematous paws, erythema in the extremities, and lameness. CT scans revealed necrotic lysis of chondrocytes, formation of fissures, visible hemorrhage, connective tissue hyperplasia, and focal infiltration of lymphocytes in the intervertebral discs. At week 14, the PGISp mice were randomly divided into three groups and administered different doses of hUCMSCs (0.25, 0.5, and 1.0×107 cells/kg, iv, QOW×2, n=10). To assess the therapeutic effects of hUCMSCs, we evaluated Th cell subsets in the spleen, spleen and thymus coefficients, peripheral blood inflammatory factors, and pathological and imaging observations of the spines and lumbar spines in the PGISp mice. The results demonstrated that injection of hUCMSCs shifted the balance axis between Th1 and Th2 cells in the spleen towards Th2 cells. Moreover, the spleen coefficient and levels of inflammatory cytokines (TNF-α and CCL-2) in the serum decreased after hUCMSC injection. CT imaging and pathological analysis indicated that hUCMSC treatment inhibited ectopic osteogenesis and maintained clear small joint gaps, which slowed down the progression of structural lesions in the disc, nucleus pulposus, fibrous ring, and cartilage in PGISp mice. Administering hUCMSCs at the 14th week after modeling proved to be an effective treatment for PGISp mice. This experiment offers a valuable reference for the pre-clinical use of hUCMSCs in the treatment of AS.

Preclinical Evaluation of Effi cacy of Processed PRP and Fresh PRP in Diabetic Wound Healing

Background: One in four people with diabetes will experience diabetic wounds at some point in their lifespan, which is among the diabetes complications that have the worst eff ects on quality of life. The study’s objective was a comparative preclinical study of the effi cacy of fresh platelet-rich plasma (PRP) Vs L-PRP in diabetic wound. Methods: Twenty four rabbits were used to study the effi cacy. Diabetes was generated in the rabbits, and the diabetic wound’s perilesional region received PRP treatment. The comparative evaluation by done by counting the wound area and rate of healing. Results: There was more than three folds rise in growth factors in lyophillised-PRP than compared to fresh PRP. The rate of wound healing was much fast in lyophilised PRP group. In the control group the wound was unhealed by 30th day and also showed pus cell formation and symptoms of infection. However, it was completely healed on 25th day when treated with L-PRP stored at 8℃. Conclusion: The outcomes prompted clinical research to compare L-PRP to fresh PRP’s effi cacy.

Pre-Clinical Evaluation of Efficacy and Safety of Human Limbus-Derived Stromal/Mesenchymal Stem Cells with and without Alginate Encapsulation for Future Clinical Applications.

Corneal opacification or scarring is one of the leading causes of blindness worldwide. Human limbus-derived stromal/mesenchymal stem cells (hLMSCs) have the potential of clearing corneal scarring. In the current preclinical studies, we aimed to determine their ability to heal the scarred corneas, in a murine model of corneal scar, and examined their ocular and systemic toxicity after topical administration to rabbit eyes. The hLMSCs were derived from human donor corneas and were cultivated in a clean room facility in compliance with the current good manufacturing practices (cGMP). Before the administration, the hLMSCs were analyzed for their characteristic properties including immunostaining, and were further subjected to sterility and stability analysis. The corneas (right eye) of C57BL/6 mice (n = 56) were stripped of their central epithelium and superficial anterior stroma using a rotary burr (Alger Brush® II). Few mice were left untreated (n = 8), while few (n = 24) were treated immediately with hLMSCs after debridement (prophylaxis group). The rest (n = 24, scar group) were allowed to develop corneal scarring for 2 weeks and then treated with hLMSCs. In both groups, the treatment modalities included encapsulated (En+) and non-encapsulated (En-) hLMSCs and sham (vehicle) treatment. The follow-up (4 weeks) after the treatment or debridement included clinical photography, fluorescein staining, and optical coherence tomography at regular intervals. All the images and scans were analyzed using ImageJ software to assess the changes in corneal haze, scar area, and the reflectivity ratio of the epithelium to the stroma. The scar area and the scar intensity were found to be decreased in the groups that received hLMSCs. The reflectivity of the stroma was found to be normalized to the baseline levels before the debridement in the eyes that were treated with hLMSCs, relative to the untreated. In the safety study, the central corneas of the left eye of 18 New Zealand rabbits were scraped with a needle and then treated with En+ hLMSCs, En- hLMSCs, and the sham (n = 6 each). Rabbits were then followed up for 4 weeks, during which blood and tear samples were collected at regular intervals. These rabbits were then assessed for changes in the quantities of inflammatory markers (TNF-α, IL-6, and IgE) in the sera and tears, changes in the ocular surface observations such as intraocular pressure (IOP), and the hematological and clinical chemistry parameters. Four weeks later, the rabbits were euthanized and examined histopathologically. No significant changes in conjunctival congestion, corneal clarity, or IOP were noticed during the ophthalmic examination. The level of inflammatory molecules (TNF-α and IL-6 TNF-α) and the hematological parameters were similar in all groups without any significant changes. Histological examination of the internal organs and ocular tissues did not reveal any abnormalities. The results of these studies summarize that the En+ and En- hLMSCs are not harmful to the recipient and potentially restore the transparency of debrided or scarred corneas, indicating that hLMSCs can be assessed for clinical use in humans.

Pre-clinical efficacy evaluation of human umbilical cord mesenchymal stem cells for ischemic stroke.

This study explored the underlying therapeutic mechanism of human umbilical cord mesenchymal stem cells (hUCMSCs) for ischemic stroke (IS), and determined the optimal administration time windows and dose-effect relationship. The levels of SDF-1α, IL-10, IL-6, TNF-α, BDNF, IL-1β, and VEGF-A factors in serum and brain tissue lysate were measured by ELISA. The pathological status of brain tissues was evaluated by Hematoxylin-Eosin (HE) staining, and apoptosis of nerve cells was detected by tunel. The protein expression of CXCR-4, NeuN, and Nestin in the brain tissues was assessed through immunofluorescence. The balance beam, forelimb muscle strength, and limb placement were tested on MCAO rats at different time points and doses. The infarct area of the rat brain tissues was measured at the end of the experiment. The hUCMSC treatment during the acute phase of MCAO significantly reduced the secretion of IL-6, TNF-α, IL-1β but increased IL-10 in serum, and the levels of SDF-α and BDNF in serum and brain tissues lysate were also increased. The pathological results showed that there were more neurons in the treatment group compared to the model group. Immunofluorescence assays showed that the expression of CXCR4、Nestin、NeuN was relatively higher than that in the model group. The d4 and d7 treatment significantly improves the motor function, promotes the recovery of forelimb muscle strength, increases the forelimb placement rate and reduces the scope of cerebral infarction, but the d14 treatment group has less therapeutic effect compared to the d4 and d7 treatment. The 2×107/kg treatment showed the best therapeutic effect, followed by the 1×107/kg treatment, and the worst is 0.5×107/kg treatment from the test of balance beam, forelimb muscle strength, limb placement and the infarct area of the rat brain tissues. The hUCMSCs can inhibit the infiltration of inflammatory cells in the brain tissue, and promote the repair of brain tissue structure and function. Early intervention by injecting high-dose of hUCMSCs can significantly improve the recovery of neurological/motor function and reduce the size of cerebral infarction in rats.

Abstract 590: Humanized PD-1/LAG-3 mice for preclinical evaluation of combination therapy

Abstract Lymphocyte activation gene 3 (LAG-3) is a member of the immunoglobulin superfamily which shares homolog with CD4 and binds to MHC II with higher affinity. It is expressed on activated T cells, regulatory T cells (Tregs), natural killer cells and plasmacytoid dendritic cells, and inhibits their activation. Blocking LAG-3 activity is expected to provide therapeutic benefits in the treatment of cancer, especially when combined with PD-1 blockade. Due to the low homology between human and mouse LAG-3 and PD-1 and in order to enable increased translatability of preclinical in-vivo efficacy evaluation of immune checkpoint antibodies, we generated double humanized mice by replacing the extracellular domain of mouse LAG-3 and PD-1 with the corresponding human sequences. Homozygous double humanized mice express chimeric LAG-3 and PD-1 at comparable levels to mouse LAG-3 and PD-1 respectively in wildtype mice. When treated with human LAG-3 antibody (anti-LAG-3) or human PD-1 antibody (anti-PD-1), CT26 tumor growth was inhibited in a dose-dependent manner, proving that both humanized proteins are functional. However, not all tumor types respond to anti-LAG-3 or anti-PD-1 the same. To identify the suitable tumor models for preclinical efficacy evaluation of anti-LAG-3 and anti-PD-1 combo therapy, we engrafted several syngeneic tumor models onto our mice. The growth of subcutaneously engrafted MC38 colon tumor was mildly inhibited by anti-PD-1, but strongly inhibited in the presence of anti-LAG-3. Similarly, B16F10 melanoma tumor showed modest growth inhibition when treated with anti-PD-1 or anti-LAG-3 separately, while combination therapy significantly repressed tumor growth. However, neither monotherapies of anti-LAG-3 and anti-PD-1 nor combination treatment effectively inhibited tumorigenesis of LLC1 derived lung cancer, indicating that this tumor is likely insensitive to PD-1 and LAG-3 blockade. Collectively, these data indicate that double humanized PD-1 and LAG-3 mice are a powerful tool to evaluate the therapeutic efficacies of anti-hPD-1 and anti-hLAG-3 treatment in different types of tumor in vivo. Citation Format: Feifei Duan, Xiaoliu Yang, Cunxiang Ju, Jing Zhao, Xiang Gao, Santi Suryani Chen. Humanized PD-1/LAG-3 mice for preclinical evaluation of combination therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 590.

Abstract 1665: Humanized mice for preclinical efficacy evaluation of drugs targeting CD73

Abstract CD73 expressed in Treg surface facilities the hydrolysis of AMP into adenosine which inhibits the activation, expansion and homing of T effector cells.Therapeutic efficiency of CD73 mAb had been studied in C57BL/6 and BALB/C mice xenografted with several murine cancer cell lines. However, for human CD73 mAb with no binding to murine CD73, CD73 humanized mouse models are essential for medicinal development.We established CD73 humanized mouse model (hCD73) on C57BL/6 and BALB/c background in which the mCD73 was replaced with hCD73. Similar expression level of hCD73 in peripheral blood was observed compared with mCD73 in wildtype mice. Besides, the proportion of T, B and NK cells in spleen of hCD73 mice were also analogy to that in wildtype mice. After treating with anti-hCD73 antibody, tumor growth was inhibited in our CT-26-hCD73 tumor model.Furthermore, hPD1/hPDL1/hCD73 mouse models were also established on C57BL/6 and BALB/c backgrounds based on hCD73 mice. However, a better anti-tumor effect of anti-CD73 antibody was found on BALB/c-hPD1/hPDL1/hCD73 bearing CT26 than that on B6-hPD1/hPDL1/hCD73 bearing MC38. Besides, Combination of anti-CD73 and anti-PD1 significant elevated anti-tumor effect comparing with anti-CD73 and anti-PD1 mono therapy in BALB/c-hPD1/hPDL1/hCD73 mice bearing CT26-hPDL1hCD73.In conclusion, BALB/c-hPD1/hPDL1/hCD73 is a well efficient mouse model for therapeutic effect study of anti-CD73 and relevant combination therapy. Citation Format: Xing Liu, Cunxiang Ju, Hongyan Sun, Jing Zhao, Xiang Gao, Zhiying Li. Humanized mice for preclinical efficacy evaluation of drugs targeting CD73 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1665.

Abstract 5623: CD137 humanized mice for preclinical efficacy evaluation of therapeutic antibodies

Abstract CD137 (41-BB, tumor necrosis factor receptor superfamily 9), expressed on activated T cells and NK cells, has gained increased attention as an anti-tumor target because of remarkable clinical efficacy using either a single agent or in combination with other immune checkpoint inhibitors. We constructed CD137 humanized mice based on two different backgrounds, C57BL6 and BALB/c mice, as well as dual-target and triple-target mice crossbred with PD1/PDL1 humanized mice to create an ideal model to study CD137 target drugs. The normal immune cell population in peripheral blood were not affected in CD137 humanized mice, and hCD137 was expressed on T cells after the stimulation with a anti CD3 antibody. We verified the efficacy of anti-CD137 drugs in BALB/c-hCD137 mice inoculated with different cancer cell lines (i.e. CT26, EMT6 and 4T1). The drug Urelumab showed a dramatic response in the hCD137 mice model inoculated with CT26 and EMT6 but not with 4T1 cell line. In a rechallenge study, no tumors grew in tumor-free mice previously treated with Urelumab, with effector memory T cells increased in peripheral blood, indicating Urelumab has a relatively long-lasting anti-tumor effect. The combination of Urelumab and anti-PD1 has a stronger tumor growth inhibition effect than that of anti-CD137 or anti-PD1 monotherapy on dual-target or triple target mice. These data show that the humanized CD137 mouse is a suitable model for evaluating the monotherapies or combination therapies targeting CD137. Citation Format: Yunlong Jiang, Tingting Gu, Weiwei Yu, Hongyan Sun, Mingkun Zhang, Juan Liang, Shuai Li, Cunxiang Ju, Jing Zhao, Xiang Gao, Mark W. Moore. CD137 humanized mice for preclinical efficacy evaluation of therapeutic antibodies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5623.

Abstract 5194: BALB/c mice with humanized VISTA: A novel GEMM for preclinical evaluation of therapeutic antibodies against VISTA

Abstract VISTA, also known as PD1H, is an immune-checkpoint receptor mainly expressed in immune cells, including macrophages, conventional dendritic cells, monocytes and circulating neutrophils. As a negative regulator of T cell activation, VISTA inhibits T cell proliferation and attenuates the production of cytokines. Studies have shown that VISTA expression is increased in infiltrating immune cells found in the tumor microenvironment and that blocking pathways that lead to VISTA activation can enhance antitumor immune responses in mice. Based on this, antibodies targeting VISTA are promising leads for cancer therapy. Preclinical efficacy evaluation of antibodies again human VISTA requires the expression of human VISTA in animal models, since difference in extracellular domains may affect antibody recognition while the overall homology between the two proteins is only 77%. To meet this need, we established a humanized mouse model in which the extracellular domain of mVISTA is replaced with that of hVISTA while the trans-membrane and cytoplasmic domains remain intact. In order to confirm the activity of the chimeric protein in our mice, we evaluated the anti-tumor effect of proven VISTA antibodies in homozygous hVISTA mice engrafted with CT26 tumor subcutaneously. Consistent with previous studies, the growth of CT26 tumor was inhibited after VISTA antibody treatment, indicating the humanized VISTA mice are suitable for efficacy evaluation of human VISTA antibodies. Moreover, we evaluated the anti-tumor effect of a combination of PD-L1 antibody and VISTA antibody in these mice. Interestingly, the combined use of PD-L1 antibody and VISTA antibody led to significantly enhanced tumor regression than either antibody. Taken together, BALB/c-hVISTA mouse is a novel non-human animal model appropriate for preclinical efficacy study of human VISTA antibodies. Citation Format: Weiwei Yu, Honghong Bao, Shuai Li, Chao Ju, Hongyan Sun, Hao Qi, Cunxiang Ju, Jing Zhao, Xiang Gao. BALB/c mice with humanized VISTA: A novel GEMM for preclinical evaluation of therapeutic antibodies against VISTA [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5194.

Preclinical efficacy evaluation of two commercially available anti-snake venom against naja nigricollis induced envenomation

Background: The biochemical and immunological variations of snake venom components lead to many challenges in manufacturing appropriate anti snake venom (ASV). These variations have negatively impacted clinical outcomes due to the availability of ineffffective ASVs in countries where the manufacturing venom does not originate. There are reports of ineffffective ASVs exported to some African countries with public health and economic consequences on the already debilitating crisis. Recently, there have been calls and publications to draw the attention of policymakers and regional regulators on the need for preclinical and clinical data related to ASV, especially when manufactured from other regions. We therefore, screened the two most commercially available antisnake venom in Northern Nigeria against the most medically important cobra venom (N. nigricollis). Methods: N. nigricollis venom was manually milked from fifive N. nigricollis captured from the wild and the LD50 of venom was determined using probit analysis. The effiffifficacy evaluation was conducted using the classical world health organization's preclinical mixing of venom/ASV methods on the lethal, hemorrhagic, hemolytic and necrotic effffect of the venom in mice and rabbit blood. Result: The median lethal dose (LD50) of Naja nigricollis venom was estimated to be 1.0 mg/kg as calculated using Probit analysis. The two ASVs used for this study; EchiTab Plus-ICP and Premium Antivenom (PAV), provided protection (100%) against venom-induced lethality in mice except at the dose of 100l/mouse, where the PAV provided only 33% protection. All the administered doses of both EchiTab-Plus-ICP and PAV showed statistically signifificant reduction (p<0.001) in the mean hemorrhagic diameter when compared with the control group (19.12±1.95 mm). There was also signifificant reduction (p<0.001) in the mean necrotic diameter in all the groups compared to the control group (8.58±1.33 ml). Two dilutions of EchiTab-Plus-ICP (100 and 200 l) were able to signifificantly reduce (>50%) venom-induced hemolysis by 58 and 62% respectively, compared with the venom control group. On the other hand, such reduction was not observed with PAV. Conclusion: The two most commercially available ASV in Northern Nigeria, EchiTab Plus-ICP and Premium Antivenom, were signifificantly (P > 0.01) effffective against lethality and venom-induced pathological parameters from Naja nigricollis envenoming, including; hemolysis, hemorrhagic and necrotic lesions, with EchiTab Plus-ICPshowing better activity.

Evaluation of Preclinical Efficacy of Human Umbilical Cord Mesenchymal Stem Cells in Ankylosing Spondylitis

Evaluation of Preclinical Efficacy of Human Umbilical Cord Mesenchymal Stem Cells in Ankylosing Spondylitis

Cabozantinib for HCC Treatment, From Clinical Back to Experimental Models.

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer-related mortality worldwide. Patients with early-stage HCC can be treated successfully with surgical resection or liver transplantation. However, the usual late diagnosis of HCC precludes curative treatments, and systemic therapies are the only viable option for inoperable patients. Sorafenib, an orally available multikinase inhibitor, is a systemic therapy approved for treating patients with advanced HCC yet providing limited benefits. Consequently, new drugs have been developed to overcome sorafenib resistance and improve patients’ prognoses. A new promising strategy is using c-MET inhibitors, such as cabozantinib, as activation of c-MET occurs in up to 40% of HCC patients. In particular, cabozantinib, in combination with the checkpoint inhibitor atezolizumab, is currently in phase 3 clinical trial for HCC, and the results are eagerly awaited. Herein, we summarize and review the drugs approved for the treatment of advanced HCC, mainly focusing on the clinical and preclinical efficacy evaluation of cabozantinib. Also, we report the available preclinical data on cabozantinib-based combination therapies for HCC, current obstacles for cabozantinib therapy, and the future directions for cabozantinib-based treatment for HCC.