Patient-derived Tumor Xenograft Models Research Articles

IMPA1-derived inositol maintains stemness in castration-resistant prostate cancer via IMPDH2 activation.

Acquisition of prostate cancer stem cells (PCSCs) manifested during androgen ablation therapy (ABT) contributes to castration-resistant prostate cancer (CRPC). However, little is known about the specific metabolites critically orchestrating this process. Here, we show that IMPA1-derived inositol enriched in PCSCs is a key metabolite crucially maintaining PCSCs for CRPC progression and ABT resistance. Notably, conditional Impa1 knockout in the prostate abrogates the pool and properties of PCSCs to orchestrate CRPC progression and prolong the survival of TRAMP mice. IMPA1-derived inositol serves as a cofactor that directly binds to and activates IMPDH2, which synthesizes guanylate nucleotides for maintaining PCSCs with ARlow/- features leading to CRPC progression and ABT resistance. IMPA1/inositol/IMPDH2 axis is upregulated in human prostate cancer, and its overexpression predicts poor survival outcomes. Genetically and pharmacologically targeting the IMPA1/inositol/IMPDH2 axis abrogates CRPC and overcomes ABT resistance in various CRPC xenografts, patient-derived xenograft (PDX) tumor models, and TRAMP mouse models. Our study identifies IMPDH2 as an inositol sensor whose activation by inositol represents a key mechanism for maintaining PCSCs for CRPC and ABT resistance.

Ex Vivo Intestinal Organoid Models: Current State-of-the-Art and Challenges in Disease Modelling and Therapeutic Testing for Colorectal Cancer

Despite improvements in participation in population-based screening programme, colorectal cancer remains a major cause of cancer-related mortality worldwide. Targeted interventions are desirable to reduce the health and economic burden of this disease. Two-dimensional monolayers of colorectal cancer cell lines represent the traditional in vitro models for disease and are often used for diverse purposes, including the delineation of molecular pathways associated with disease aetiology or the gauging of drug efficacy. The lack of complexity in such models, chiefly the limited epithelial cell diversity and differentiation, attenuated mucus production, lack of microbial interactions and mechanical stresses, has driven interest in the development of more holistic and physiologically relevant in vitro model systems. In particular, established ex vivo patient-derived explant and patient-derived tumour xenograft models have been supplemented by progress in organoid and microfluidic organ-on-a-chip cultures. Here, we discuss the applicability of advanced culturing technologies, such as organoid systems, as models for colorectal cancer and for testing chemotherapeutic drug sensitivity and efficacy. We highlight current challenges associated with organoid technologies and discuss their future for more accurate disease modelling and personalized medicine.

Establishment of matched bladder cancer PDX and PDX-derived organoid model and evaluation of anti-tumor efficacy of abemaciclib.

Bladder cancer is one of the most common malignancies of the urinary system and there's a significant unmet need for new effective therapeutics for bladder cancer. The limited number of available models to study malignant bladder tumors is one of the obstructions in developing bladder cancer therapeutics. Patient-derived xenograft (PDX) and organoid (PDO) models are more representatives of human cancer than cell lines and cell line-derived xenograft (CDX) and are likely to be more promising and efficient in predicting drug response and finding new therapeutics. Three pairs of patient-derived xenograft (PDX) models of bladder cancer and their corresponding PDX-derived organoids (PDXOs) were successfully established. These models were utilized to assess the efficacy of abemaciclib. The sensitivity of the drug was determined through the Cell Counting Kit-8 (CCK8) assay in PDXO cultures, corroborated by the EdU incorporation assay. Additionally, the in vivo tumor growth was monitored in the matched PDX models. In vitro PDXO cultures and in vivo PDX tumor models consistently demonstrated that abemaciclib had varying degrees of inhibitory effects across different bladder cancer (BC) patients. Notably, our study further revealed that treatment with abemaciclib significantly modified the expression patterns of CyclinD1/CDK4. This was achieved by not only diminishing their expression levels but also by shifting their expression from a membrane-associated localization to the nucleus. Our research provided compelling evidence attesting to the reliability and potential of PDX and PDXO models in the realm of precision medicine. These models are instrumental in identifying patients who are likely to respond favorably to a specific drug treatment.

The interaction between UBR7 and PRMT5 drives PDAC resistance to gemcitabine by regulating glycolysis and immune microenvironment

Pancreatic ductal adenocarcinoma (PDAC) is a common malignant tumor of the digestive tract. Although gemcitabine and other therapeutic agents are effective in patients with advanced and metastatic pancreatic cancer, drug resistance has severely limited their use. However, the mechanisms of gemcitabine resistance in pancreatic cancer are poorly understood. In this study, ATAC-seq, ChIP-seq, and RNA-seq were performed to compare chromatin accessibility and gene expression in a patient-derived tumor xenograft (PDX) model of pancreatic cancer with or without gemcitabine resistance. Analyzing these sequencing data, we found a dramatic change in chromatin accessibility in the PDX model of gemcitabine-resistant tissues and identified a key gene, UBR7, which plays an important role in mediating gemcitabine resistance. Further research found that depletion of UBR7 significantly increased pancreatic carcinogenesis and the immunosuppressive microenvironment. Mechanistically, depleted UBR7 increased the stability of PRMT5, thereby promoting glycolysis in pancreatic cancer cells. Finally, an inhibitor that blocks PRMT5 (DS-437) significantly reduced gemcitabine resistance in pancreatic cancer caused by UBR7 depletion. In conclusion, our results illustrate that the UBR7-PRMT5 axis is a key metabolic regulator of PDAC and a promising target for the clinical treatment of gemcitabine resistance in PDAC.

Nifuratel Induces Triple-Negative Breast Cancer Cell G2/M Phase Block and Apoptosis by Regulating GADD45A.

(1) Background: Nifuratel (NF113), derived from nitrofuran, has a specific anti-tumor effect. However, the potential mechanisms of NF113 in triple-negative breast cancer remain unknown. (2) Methods: In the study, CCK8 assay and colony formation assays were used to evaluate the inhibition effect of NF113 on cell proliferation. Apoptosis and cell cycle distribution were tested by flow cytometry. The mechanism of NF113's anti-tumor effect was predicted by transcriptome sequencing and verified by using PCR and Western blot experiments. Breast cancer organoids constructed from the patient-derived tumor xenograft model and the MDA-MB-468 xenograft mouse model were established to evaluate the effect of NF113. (3) Results: Our study showed that NF113 had an anti-tumor effect on triple-negative breast cancer both in vitro and in vivo. NF113 also induced apoptosis and G2/M phase arrest in triple-negative breast cancer cells. Our experimental data further verified that NF113 reduced GADD5A mRNA and protein expression, which were significantly upregulated in breast cancer, with downstream CDC25C and AKT phosphorylation changes. (4) Conclusions: Our data provided compelling evidence that NF113 inhibited breast cancer growth via upregulating GADD45A. Conclusion: NF113 was able to exert inhibitory effects on the proliferation of triple-negative breast cancer in vivo and in vitro, which may induce G2/M phase arrest via the GADD45A/CyclinB/CDK1 pathway and apoptosis via GADD45A/JNK/P38.

Preclinical Evaluation of AZD6422, an Armored Chimeric Antigen Receptor T Cell Targeting CLDN18.2 in Gastric, Pancreatic, and Esophageal Cancer.

CLDN18.2 is a surface membrane protein crucial for maintaining tight junctions in gastric mucosal cells and is highly expressed in gastric, esophageal, and pancreatic cancers. Thus, CLDN18.2 is suited for exploration as a clinical target for chimeric antigen receptor T-cell (CAR-T) therapy in these indications. Although CAR-T therapies show promise, a challenge faced in their development for solid tumors is the immunosuppressive tumor microenvironment, often characterized by the presence of immune and stromal cells secreting high levels of transforming growth factor beta (TGF-β). Addition of TGF-β armoring can potentially expand CAR-T activity in solid tumors. We report on the preclinical development of a CLDN18.2-targeting CAR-T showing effectiveness in CLDN18.2-positive gastric, esophageal, and pancreatic tumor models. The lead lentivirus product contains a unique single-chain variable fragment, CD28 and CD3z costimulatory and signaling domains, and dominant negative TGF-β receptor armoring, enhancing targeting and safety and counteracting suppression. We developed a shortened cell manufacturing process to enhance the potency of the final product, AZD6422. AZD6422 exhibited significant antitumor activity and tolerability in multiple patient-derived tumor xenograft models with various CLDN18.2 and TGF-β levels, as determined by immunohistochemistry. Efficacy of armored CAR-Ts in tumor models with elevated TGF-β was increased in vitro and in vivo. In vitro restimulation assays established greater persistence and cytolytic function of AZD6422 compared with a traditionally manufactured CAR-T. AZD6422 was safe and efficacious in patient-derived, CLDN18.2-positive murine models of gastrointestinal cancers. Our data support further clinical development of AZD6422 for patients with these cancers.

Highly Efficient Synergistic Chemotherapy and Magnetic Resonance Imaging for Targeted Ovarian Cancer Therapy Using Hyaluronic Acid-Coated Coordination Polymer Nanoparticles.

The diagnosis and treatment of ovarian cancer (OC) are still a grand challenge, more than 70% of patients are diagnosed at an advanced stage with a dismal prognosis. Magnetic resonance imaging (MRI) has shown superior results to other examinations in preoperative assessment, while cisplatin-based chemotherapy is the first-line treatment for OC. However, few previous studies have brought together the two rapidly expanding fields. Here a technique is presented using cisplatin prodrug (Pt-COOH), Fe3+, and natural polyphenols (Gossypol) to construct the nanoparticles (HA@PFG NPs) that have a stable structure, controllable drug release behavior, and high drug loading capacity. The acidic pH values in tumor sites facilitate the release of Fe3+, Pt-COOH, and Gossypol from HA@PFG NPs. Pt-COOH with GSH consumption and cisplatin-basedchemotherapy plus Gossypol with pro-apoptotic effects displays asynergisticeffect forkillingtumorcells. Furthermore, the release of Fe3+ at the tumor sites promotes ferroptosis and enables MRI imaging of OC. Inthe patient-derived tumor xenograft (PDX)model, HA@PFG NPs alleviate the tumor activity. RNA sequencing analysis reveals that HA@PFG NPs ameliorate OC symptoms mainly through IL-6 signal pathways. This work combines MRI imaging with cisplatin-based chemotherapy, which holds great promise for OC diagnosis and synergistic therapy.

Characterizing the Cell-Free Transcriptome in a Humanized Diffuse Large B-Cell Lymphoma Patient-Derived Tumor Xenograft Model for RNA-Based Liquid Biopsy in a Preclinical Setting.

The potential of RNA-based liquid biopsy is increasingly being recognized in diffuse large B-cell lymphoma (DLBCL), the most common subtype of non-Hodgkin's lymphoma. This study explores the cell-free transcriptome in a humanized DLBCL patient-derived tumor xenograft (PDTX) model. Blood plasma samples (n = 171) derived from a DLBCL PDTX model, including 27 humanized (HIS) PDTX, 8 HIS non-PDTX, and 21 non-HIS PDTX non-obese diabetic (NOD)-scid IL2Rgnull (NSG) mice were collected during humanization, xenografting, treatment, and sacrifice. The mice were treated with either rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP), CD20-targeted human IFNα2-based AcTaferon combined with CHOP (huCD20-Fc-AFN-CHOP), or phosphate-buffered saline (PBS). RNA was extracted using the miRNeasy serum/plasma kit and sequenced on the NovaSeq 6000 platform. RNA sequencing data of the formalin-fixed paraffin-embedded (FFPE) tissue and blood plasma samples of the original patient were included. Flow cytometry was performed on immune cells isolated from whole blood, spleen, and bone marrow. Bulk deconvolution was performed using the Tabula Sapiens v1 basis matrix. Both R-CHOP and huCD20-Fc-AFN-CHOP were able to control tumor growth in most mice. Xenograft tumor volume was strongly associated with circulating tumor RNA (ctRNA) concentration (p < 0.001, R = 0.89), as well as with the number of detected human genes (p < 0.001, R = 0.79). Abundance analysis identified tumor-specific biomarkers that were dynamically tracked during tumor growth or treatment. An 8-gene signature demonstrated high accuracy for assessing therapy response (AUC 0.92). The tumoral gene detectability in the ctRNA of the PDTX-derived plasma was associated with RNA abundance levels in the patient's tumor tissue and blood plasma (p < 0.001), confirming that tumoral gene abundance contributes to the cell-free RNA (cfRNA) profile. Decomposing the transcriptome, however, revealed high inter- and intra-mouse variability, which was lower in the HIS PDTX mice, indicating an impact of human engraftment on the stability and profile of cfRNA. Immunochemotherapy resulted in B cell depletion, and tumor clearance was reflected by a decrease in the fraction of human CD45+ cells. Lastly, bulk deconvolution provided complementary biological insights into the composition of the tumor and circulating immune system. In conclusion, the blood plasma-derived transcriptome serves as a biomarker source in a preclinical PDTX model, enables the assessment of biological pathways, and enhances the understanding of cfRNA dynamics.

Dronedarone inhibits the proliferation of esophageal squamous cell carcinoma through the CDK4/CDK6-RB1 axis in vitro and in vivo.

Treatment options for patients with esophageal squamous cell carcinoma (ESCC) often result in poor prognosis and declining health-related quality of life. Screening FDA-approved drugs for cancer chemoprevention is a promising and cost-efficient strategy. Here, we found that dronedarone, an antiarrhythmic drug, could inhibit the proliferation of ESCC cells. Moreover, we conducted phosphorylomics analysis to investigate the mechanism of dronedarone-treated ESCC cells. Through computational docking models and pull-down assays, we demonstrated that dronedarone could directly bind to CDK4 and CDK6 kinases. We also proved that dronedarone effectively inhibited ESCC proliferation by targeting CDK4/CDK6 and blocking the G0/G1 phase through RB1 phosphorylation inhibition by in vitro kinase assays and cell cycle assays. Subsequently, we found that knocking out CDK4 and CDK6 decreased the susceptibility of ESCC cells to dronedarone. Furthermore, dronedarone suppressed the growth of ESCC in patient-derived tumor xenograft models in vivo. Thus, our study demonstrated that dronedarone could be repurposed as a CDK4/6 inhibitor for ESCC chemoprevention.

C-Myc alone is enough to reprogram fibroblasts into functional macrophages

BackgroundMacrophage-based cell therapy is promising in solid tumors, but the efficient acquisition of macrophages remains a challenge. Induced pluripotent stem cell (iPSC)-induced macrophages are a valuable source, but time-consuming and costly. The application of reprogramming technologies allows for the generation of macrophages from somatic cells, thereby facilitating the advancement of cell-based therapies for numerous malignant diseases.MethodsThe composition of CD45+ myeloid-like cell complex (MCC) and induced macrophage (iMac) were analyzed by flow cytometry and single-cell RNA sequencing. The engraftment capacity of CD45+ MCC was evaluated by two transplantation assays. Regulation of c-Myc on MafB was evaluated by ChIP-qPCR and promoter reporter and dual luciferase assays. The phenotype and phagocytosis of iMac were explored by flow cytometry and immunofluorescence. Leukemia, breast cancer, and patient-derived tumor xenograft models were used to explore the anti-tumor function of iMac.ResultsHere we report on the establishment of a novel methodology allowing for reprogramming fibroblasts into functional macrophages with phagocytic activity by c-Myc overexpression. Fibroblasts with ectopic expression of c-Myc in iPSC medium rapidly generated CD45+ MCC intermediates with engraftment capacity as well as the repopulation of distinct hematopoietic compartments. MCC intermediates were stably maintained in iPSC medium and continuously generated functional and highly pure iMac just by M-CSF cytokine stimulation. Single-cell transcriptomic analysis of MCC intermediates revealed that c-Myc up-regulated the expression of MafB, a major regulator of macrophage differentiation, to promote macrophage differentiation. Characterization of the iMac activity showed NF-κB signaling activation and a pro-inflammatory phenotype. iMac cells displayed significantly increased in vivo persistence and inhibition of tumor progression in leukemia, breast cancer, and patient-derived tumor xenograft models.ConclusionsOur findings demonstrate that c-Myc alone is enough to reprogram fibroblasts into functional macrophages, supporting that c-Myc reprogramming strategy of fibroblasts can help circumvent long-standing obstacles to gaining “off-the-shelf” macrophages for anti-cancer immunotherapy.

The PARP1 selective inhibitor saruparib (AZD5305) elicits potent and durable antitumor activity in patient-derived BRCA1/2-associated cancer models

BackgroundPoly (ADP-ribose) polymerase 1 and 2 (PARP1/2) inhibitors (PARPi) are targeted therapies approved for homologous recombination repair (HRR)-deficient breast, ovarian, pancreatic, and prostate cancers. Since inhibition of PARP1 is sufficient to cause synthetic lethality in tumors with homologous recombination deficiency (HRD), PARP1 selective inhibitors such as saruparib (AZD5305) are being developed. It is expected that selective PARP1 inhibition leads to a safer profile that facilitates its combination with other DNA damage repair inhibitors. Here, we aimed to characterize the antitumor activity of AZD5305 in patient-derived preclinical models compared to the first-generation PARP1/2 inhibitor olaparib and to identify mechanisms of resistance.MethodsThirteen previously characterized patient-derived tumor xenograft (PDX) models from breast, ovarian, and pancreatic cancer patients harboring germline pathogenic alterations in BRCA1, BRCA2, or PALB2 were used to evaluate the efficacy of AZD5305 alone or in combination with carboplatin or an ataxia telangiectasia and Rad3 related (ATR) inhibitor (ceralasertib) and compared it to the first-generation PARPi olaparib. We performed DNA and RNA sequencing as well as protein-based assays to identify mechanisms of acquired resistance to either PARPi.ResultsAZD5305 showed superior antitumor activity than the first-generation PARPi in terms of preclinical complete response rate (75% vs. 37%). The median preclinical progression-free survival was significantly longer in the AZD5305-treated group compared to the olaparib-treated group (> 386 days vs. 90 days). Mechanistically, AZD5305 induced more replication stress and genomic instability than the PARP1/2 inhibitor olaparib in PARPi-sensitive tumors. All tumors at progression with either PARPi (39/39) showed increase of HRR functionality by RAD51 foci formation. The most prevalent resistance mechanisms identified were the acquisition of reversion mutations in BRCA1/BRCA2 and the accumulation of hypomorphic BRCA1. AZD5305 did not sensitize PDXs with acquired resistance to olaparib but elicited profound and durable responses when combined with carboplatin or ceralasertib in 3/6 and 5/5 models, respectively.ConclusionsCollectively, these results show that the novel PARP1 selective inhibitor AZD5305 yields a potent antitumor response in PDX models with HRD and delays PARPi resistance alone or in combination with carboplatin or ceralasertib, which supports its use in the clinic as a new therapeutic option.

Effect of ac4C acetyltransferase NAT10 on tumor progression via ATF4/ASNS mediated asparagine biosynthesis in osteosarcoma.

234 Background: Osteosarcoma is the most common primary malignant bone tumor in children and adolescents, characterized by high malignancy, high mortality, and high disability rates. Investigating the mechanism of osteosarcoma progression, identifying new targets, and developing effective therapy are of great significance for improving patient clinical outcomes. NAT10-mediated ac4C modification is widely present in mRNA and plays important roles in multiple biological processes of mRNA. NAT10 and ac4C modification also play a crucial role in the occurrence and development of malignant tumors such as bladder cancer, esophageal cancer, and breast cancer. Methods: Through RNA-seq and functional screening, NAT10 was identified as the potential therapeutic target. The biological functions of NAT10 and ac4C modification in osteosarcoma were explored in vivo and in vitro. Downstream target of NAT10 was identified through acRIP-seq combined with RNA-seq. The ac4C modification of downstream target gene were detected using RIP-qPCR and its regulatory effect on mRNA stability was explored using RNA half-life analysis. Drug screening was performed using FDA-approved drugs and a small molecule compound library to identify NAT10 inhibitors. The efficacy of inhibitors in osteosarcoma treatment is validated through in vivo, in vitro experiments and patient-derived tumor xenograft (PDX) models. Results: Functional screening targeting RNA modification regulatory factors demonstrated that inhibiting NAT10 significantly reduced the proliferation, migration and invasion of osteosarcoma cells. NAT10 knockout significantly inhibited the proliferation and metastasis of osteosarcoma cells, as well as the malignant progression in vivo. The acRIP-seq and RNA-seq revealed that ATF4 is a downstream target gene regulated by NAT10 in osteosarcoma. NAT10 promoted ac4C modification of ATF4 mRNA, enhanced the stability of ATF4 mRNA, and ATF4 promoted the transcription and expression of ASNS. ASNS catalyzes the synthesis of asparagine (Asn), thereby promoting the malignant progression of osteosarcoma. Drug screening identified Paliperidone and AG-401 as potential inhibitors of NAT10. Through cell functional experiments, orthotopic osteosarcoma models, organoids model, and PDX models, it was demonstrated that Paliperidone and AG-401 can inhibit the malignant progression of osteosarcoma. Conclusions: NAT10 was highly expressed in osteosarcoma and associated with patient prognosis. Through ac4C modification, NAT10 regulated the synthesis of asparagine mediated by ATF4/ASNS, providing materials for protein and nucleotide synthesis in tumor cells, thus promoting the malignant progression of osteosarcoma. Paliperidone and AG-401 were identified as potential NAT10 inhibitors and targeting NAT10 could be a promosing strategy in osteosarcoma treatment.

Sanggenol L induces ferroptosis in non-small cell lung cancer cells via regulating the miR-26a-1-3p/MDM2/p53 signaling pathway

Ferroptosis is a regulated cell death marked by iron-dependent lipid peroxidation. Tumor cells that survive by evading chemotherapy-induced apoptosis are vulnerable to ferroptosis. Therefore, it is particularly urgent to explore active ingredients that can selectively induce ferroptosis in cancer cells. Here, we revealed that sanggenol L, the active agent of Morus Bark, predisposed non-small cell lung cancer (NSCLC) cells to ferroptosis, evidenced by reactive oxygen species (ROS) accumulation, glutathione depletion, mitochondrial shrinkage, and lipid peroxidation. Furthermore, the ferroptosis-related miRNA array showed that sanggenol L treatment upregulated the level of miR-26a-1-3p, which directly targeted the E3 ubiquitin ligase MDM2. In addition, silencing MDM2 by miR-26a-1-3p resulted in a notable increase in p53 protein levels and decrease of its downstream target SLC7A11, ultimately triggered ferroptosis. The subcutaneous xenograft model and patient-derived tumor xenograft (PDX) model of NSCLC further confirmed the anti-tumor efficacy and safety of sanggenol L in vivo. Collectively, our data suggest that miR-26a-1-3p/MDM2/p53/SLC7A11 signaling axis plays a key role in sanggenol L-induced ferroptosis, which implies that sanggenol L can serves as an anticancer therapeutic arsenal for NSCLC.

Molecular SPECT/CT Profiling of Claudin18.2 Expression In Vivo: Implication for Patients with Gastric Cancer.

Zolbetuximab (IMAB362), a monoclonal antibody targeting Claudin18.2 (CLDN 18.2), demonstrates a significant clinical benefit in patients with advanced gastroesophageal cancers. The noninvasive assessment of CLDN18.2 expression through molecular imaging offers a potential avenue for expedited monitoring and the stratification of patients into risk groups. This study elucidates that CLDN18.2 is expressed at a noteworthy frequency in primary gastric cancers and their metastases. The iodogen method was employed to label IMAB362 with 123I/131I. The results demonstrated the efficient and reproducible synthesis of 123I-IMAB362, with a specific binding affinity to CLDN18.2. Immuno-single-photon emission computed tomography (SPECT) imaging revealed the rapid accumulation of 123I-IMAB362 in gastric cancer xenografts at 12 h, remaining stable for 3 days in patient-derived tumor xenograft models. Additionally, tracer uptake of 123I-IMAB362 in MKN45 cells surpassed that in MKN28 cells at each time point, with tumor uptake correlating significantly with CLDN18.2 expression levels. Positron emission tomography/computed tomography imaging indicated that tumor uptake of 18F-FDG and the functional/viable tumor volume in the 131I-IMAB362 group were significantly lower than those in the 123I-IMAB362 group on day 7. In conclusion, 123I-IMAB362 immuno-SPECT imaging offers an effective method for direct, noninvasive, and whole-body quantitative assessment of tumor CLDN18.2 expression in vivo. This approach holds promise for accelerating the monitoring and stratification of patients with gastric cancer.

CircPDIA3/miR-449a/XBP1 feedback loop curbs pyroptosis by inhibiting palmitoylation of the GSDME-C domain to induce chemoresistance of colorectal cancer

Although oxaliplatin (OXA) is widely used in the frontline treatment of colorectal cancer (CRC), CRC recurrence is commonly observed due to OXA resistance. OXA resistance is associated with a number of factors, including abnormal regulation of pyroptosis. It is therefore important to elucidate the abnormal regulatory mechanism underlying pyroptosis. Here, we identified that the circular RNA circPDIA3 played an important role in chemoresistance in CRC. CircPDIA3 could induce chemoresistance in CRC by inhibiting pyroptosis both in vitro and in vivo. Mechanistically, RIP, RNA pull-down and co-IP assays revealed that circPDIA3 directly bonded to the GSDME-C domain, subsequently enhanced the autoinhibitory effect of the GSDME-C domain through blocking the GSDME-C domain palmitoylation by ZDHHC3 and ZDHHC17, thereby restraining pyroptosis. Additionally, it was found that the circPDIA3/miR-449a/XBP1 positive feedback loop increased the expression of circPDIA3 to induce chemoresistance. Furthermore, our clinical data and patient-derived tumor xenograft (PDX) models supported the positive association of circPDIA3 with development of chemoresistance in CRC patients. Taken together, our findings demonstrated that circPDIA3 could promote chemoresistance by amplifying the autoinhibitory effect of the GSDME-C domain through inhibition of the GSDME-C domain palmitoylation in CRC. This study provides novel insights into the mechanism of circRNA in regulating pyroptosis and providing a potential therapeutic target for reversing chemoresistance of CRC.

A rat-based preclinical platform facilitating transcatheter hepatic arterial infusion in immunodeficient rats with liver xenografts of patient-derived pancreatic ductal adenocarcinoma

Liver metastases from pancreatic ductal adenocarcinoma (PDAC) are highly fatal. A rat-based patient-derived tumor xenograft (PDX) model is available for transcatheter therapy. This study aimed to create an immunodeficient rat model with liver xenografts of patient-derived primary PDAC and evaluate efficacy of hepatic arterial infusion chemotherapy with cisplatin in this model. Three patient-derived PDACs were transplanted into the livers of 21 rats each (totally, 63 rats), randomly assigned into hepatic arterial infusion, systemic venous infusion, and control groups (n = 7 each) four weeks post-implantation. Computed tomography evaluated tumor volumes before and four weeks after treatment. Post-euthanasia, resected tumor specimens underwent histopathological examination. A liver-implanted PDAC PDX rat model was established in all 63 rats, with first CT identifying all tumors. Four weeks post-treatment, arterial infusion groups exhibited significantly smaller tumor volumes than controls for all three tumors on second CT. Xenograft tumors histologically maintained adenocarcinoma features compared to original patient tumors. Ki67 expression was significantly lower in arterial infusion groups than in the other two for the three tumors, indicating reduced tumor growth in PDX rats. A liver-implanted PDAC PDX rat model was established as a rat-based preclinical platform. Arterial cisplatin infusion chemotherapy represents a potential therapy for PDAC liver metastasis.

Inhibition of protein translational machinery in triple-negative breast cancer as a promising therapeutic strategy

Y-box binding protein-1 (YB-1) is a proto-oncogenic protein associated with protein translation regulation. It plays a crucial role in the development and progression of triple-negative breast cancer (TNBC). In this study, we describe a promising approach to inhibit YB-1 using SU056, a small-molecule inhibitor. SU056 physically interacts with YB-1 and reduces its expression, which helps to restrain the progression of TNBC. Proteome profiling analysis indicates that the inhibition of YB-1 by SU056 can alter the proteins that regulate protein translation, an essential process for cancer cell growth. Preclinical studies on human cells, mice, and patient-derived xenograft tumor models show the effectiveness of SU056. Moreover, toxicological studies have shown that SU056 treatment and dosing are well tolerated without any adverse effects. Overall, our study provides a strong foundation for the further development of SU056 as a potential treatment option for patients with TNBC by targeting YB-1.

Abstract 2836: Assessment of therapeutic antibody efficacy without the interference of murine Fc receptors allows for investigation of human antibody-dependent cellular cytotoxicity mediated by NK cells in the FcResolv™ hIL-15 NOG mouse model

Abstract Targeted antibody therapy is applied to treat various cancer types. In addition to the primary mode of action (MOA), which involves direct binding to the tumor antigen, indirect MOA acting through the constant region (Fc) of the antibody can enhance anti-tumor efficacy. Indirect mechanisms engage the innate immune system, mediated by both the complement system (complement-dependent cytotoxicity (CDC)) and immune cells (antibody-dependent cellular phagocytosis (ADCP) and antibody-dependent cellular cytotoxicity (ADCC)). These indirect mechanisms can complicate the evaluation and accurate assessment of antibody-induced ADCC by human NK cells in current mouse models. In immune-deficient mouse strains (e.g. NOG), false positives and/or negatives may occur due to interactions with murine Fc receptors. These can either result in anti-tumor responses via activation of the murine innate immune system or can interfere with the human-targeted therapy's primary MOA. To study the response to anti-cancer antibodies without the interference of these murine Fc receptor interactions and to investigate ADCC mediated by human NK cells, a novel mouse model deficient in Fc receptors and expressing human IL-15 (FcResolv™ hIL-15 NOG) was employed for testing antibody therapies. Methods: Patient-derived xenograft (PDX) tumor models were transplanted into hIL-15 NOG and FcResolv™ hIL-15 NOG mice. A human head and neck squamous cell carcinoma and a lung adenocarcinoma PDX model were both treated with cetuximab. Treatment with pertuzumab and trastuzumab was applied in a breast ductal carcinoma PDX model. Rituximab treatment was tested in two diffuse large B cell lymphoma PDX models. Based on growth kinetics, the lung cancer PDX model was chosen for further testing of ADCC in the NK cell-humanized FcResolv™ hIL-15 NOG mouse. Results and Conclusion: There was no difference in percent tumor growth inhibition between the FcResolv™ hIL-15 NOG and hIL-15 NOG mice with regards to cetuximab treatment in the lung and head and neck cancer or for trastuzumab treatment of breast ductal carcinoma. However, pertuzumab treatment revealed a false positive efficacy, with the false positive effect more pronounced in hIL-15 NOG mice than in FcResolv™ hIL-15 NOG mice. In one of the lymphoma models, a false negative result was observed. Here, rituximab did not show notable tumor inhibition in the hIL-15 NOG mice but did in the FcResolv™ hIL-15 NOG mice. These results demonstrate that FcResolv™ hIL-15 NOG mice serve as a suitable mouse model for a more accurate assessment of the therapeutic efficacy of anti-tumor antibodies. Additionally, evaluation of human-mediated ADCC of therapeutic antibodies in NK cell-humanized FcResolv™ hIL-15 NOG allows detection of effects specifically mediated by human NK cells. Citation Format: Simone Rhein, Maria Stecklum, Monika Buczek, Janell Richardson, Jens Hoffmann. Assessment of therapeutic antibody efficacy without the interference of murine Fc receptors allows for investigation of human antibody-dependent cellular cytotoxicity mediated by NK cells in the FcResolv™ hIL-15 NOG mouse model [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 2836.

Abstract 1898: LNCB74 is a potent and safe next-generation antibody-drug-conjugate utilizing a cancer selective linker for the treatment of B7-H4 expressing cancers

Abstract The B7 family protein B7-H4 is highly expressed on a range of solid tumors including breast, ovarian, and endometrial cancers, where it may play a role in immune evasion. In non-cancerous tissues, B7-H4 expression is limited, suggesting it may be a potential target for an antibody drug conjugate (ADC). LNCB74 is a human IgG1 antibody conjugated to the potent microtubule disrupting payload monomethyl auristatin E (MMAE) with a drug-to-antibody ratio of 4 (DAR4). The ADC employs a highly selective B7-H4 antibody based upon NextCure’s expertise in B7-H4 tumor biology coupled with a glucuronidase-cleavable, site-specific linkage to an engineered cysteine in the antibody light chain via LegoChem Biosciences’ ConjuAllTM technology. This improves the safety profile and therapeutic index of the agent by a) increasing stability in circulation, b) selectively releasing payload in tumor cells, and c) reducing payload release in off-target cells. LNCB74 was further engineered with a “LALA”-mutant Fc region to minimize uptake and toxicity to immune cells. In a nonhuman primate (NHP) toxicity study, LNCB74 was well tolerated for repeat dosing and provides evidence for a superior safety profile without noticeable side effects. LNCB74 is rapidly internalized by B7-H4-expressing tumor cells, and demonstrates potent, target-specific cytotoxicity on multiple cancer cell lines. In vivo studies demonstrate a strong bystander effect following a single dose administration of LNCB74. A rapid and durable anti-tumor response has been demonstrated in multiple cell-line derived (CDX) and patient-derived xenograft (PDX) tumor models. In summary, LNCB74 is a promising ADC enabling specific targeting of B7-H4 positive cancers across a spectrum of indications. Citation Format: Daniel P. Fitzgerald, Duc N. Doan, Riley B. Peacock, Shannon M. Kahan, Suvendu Lomash, Stephen Slocum, Kwang Hwa Jung, Hwanhee Oh, Ingrid Meza, Yanira Manzanarez, Shanmugam Selvam, Dallas B. Flies, Chul-Woong Chung, Sol Langermann. LNCB74 is a potent and safe next-generation antibody-drug-conjugate utilizing a cancer selective linker for the treatment of B7-H4 expressing cancers [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 1898.

Abstract 6903: Treatment efficacy of transcatheter hepatic arterial infusion chemotherapy with cisplatin in a severe immunodeficient rat model with patient-derived primary pancreatic ductal adenocarcinoma xenografted into the liver

Abstract Purpose: Liver metastases of pancreatic ductal adenocarcinoma (PDAC) is a highly fatal disease; most patients die within 5 years. There is a critical need to identify appropriate anticancer treatments for these patients. A patient-derived tumor xenograft (PDX) model in severe immunodeficient rat with primary PDAC xenografted into the liver is suitable for evaluating transcatheter hepatic arterial infusion chemotherapy. Materials and Methods: The purpose of this study was to develop a severe immunodeficient rat model with patient-derived primary PDAC xenografted into the liver, and to assess the treatment efficacy of hepatic arterial infusion chemotherapy with cisplatin in this model. Three patient-derived tumors of PDAC were transplanted into the liver of 21 rats each, totaling 63 rats. Four weeks after transplantation, the 21 rats were randomly assigned into three treatment groups of seven rats each: hepatic arterial infusion, systemic venous infusion, and control group. Tumor volumes were evaluated on CT twice at pre-treatment and 4-weeks post-treatment. Following euthanasia of the rats, resected tumor specimens were pathologically analyzed. Results: The liver-implanted PDAC PDX rat model was established in all 63 rats. hepatic arterial infusion chemotherapy and systemic venous infusion chemotherapy with cisplatin were able to be performed in the assigned rats. The hepatic arterial infusion group significantly inhibited tumor growth and reduced Ki67 expression, indicating lower cell proliferation, compared to the control group in three PDX tumors. Conclusion: A rat-based preclinical platform was established by liver-implanted PDAC PDX rat model. Arterial cisplatin infusion chemotherapy would be one of potential therapies for PDAC liver metastases. Citation Format: Ken Kageyama, Akira Yamamoto, Masanori Ozaki, Kenjiro Kimura, Shinpei Eguchi, Ryota Tanaka, Mizue Terai, Takami Sato, Yukio Miki. Treatment efficacy of transcatheter hepatic arterial infusion chemotherapy with cisplatin in a severe immunodeficient rat model with patient-derived primary pancreatic ductal adenocarcinoma xenografted into the liver [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 6903.