Patient-derived Tumor Spheroids Research Articles

A patient-derived HCC spheroid system to model the tumor microenvironment and treatment response

Background & AimsHepatocellular carcinoma (HCC) is the third leading and fastest rising cause of cancer-related death worldwide. The discovery and preclinical development of compounds targeting HCC is hampered by the absence of authentic tractable systems recapitulating the heterogeneity of patient HCC tumors and the tumor microenvironment (TME). MethodsWe established a novel and simple patient-derived multicellular tumorspheroid model based on clinical HCC tumor tissues, processed using enzymatic and mechanical dissociation. After quality controls, 22 HCC tissues and 17 HCC serum were selected for tumorspheroid generation and perturbation studies. Cells were grown in 3D in optimized medium in presence of patient serum. Characterization of the tumorspheroid cell populations was performed by flow cytometry, immunohistochemistry and functional assays. As a proof of concept, we treated patient-derived spheroids with FDA approved anti-HCC compounds. ResultsThe model was successfully established independently from cancer etiology and grade from 22 HCC tissues. We show that the use of HCC patient serum was essential for tumorspheroid generation, the TME function and to maintain cell viability. The tumorspheroids comprised the main cell compartments including epithelial cancer cells as well as all major cell populations of the TME (cancer-associated fibroblasts, macrophages and T cells, endothelial cells). Tumorspheroids reflect HCC heterogeneity, including variability in cell type proportions and TME, and mimic the original tumor features. Moreover, we observed differential responses to FDA HCC approved drugs between donors as observed in patients. ConclusionThis patient HCC serum-tumorspheroid model provides novel opportunities for drug discovery and development as well as mechanism of action studies including compounds targeting the TME. This model will likely contribute to improve the dismal outcome of patients with HCC. Impact and implicationsHepatocellular carcinoma (HCC) is a leading and fast rising cause of cancer-related death worldwide. Despite approval of novel therapies, the outcome of advanced HCC remains unsatisfactory. By developing a novel patient-derived tumorspheroid model recapitulating tumor heterogeneity and microenvironment, we provide new opportunities for HCC drug development and analysis of mechanism of action in authentic patient tissues. The application of the patient-derived tumorspheroids combined with other HCC models will likely contribute to drug development and to improve the dismal outcome of patients with HCC.

Targeting SRSF10 might inhibit M2 macrophage polarization and potentiate anti-PD-1 therapy in hepatocellular carcinoma.

The efficacy of immune checkpoint blockade therapy in patients with hepatocellular carcinoma (HCC) remains poor. Although serine- and arginine-rich splicing factor (SRSF) family members play crucial roles in tumors, their impact on tumor immunology remains unclear. This study aimed to elucidate the role of SRSF10 in HCC immunotherapy. To identify the key genes associated with immunotherapy resistance, we conducted single-nuclear RNA sequencing, multiplex immunofluorescence, and The Cancer Genome Atlas and Gene Expression Omnibus database analyses. We investigated the biological functions of SRSF10 in immune evasion using in vitro co-culture systems, flow cytometry, various tumor-bearing mouse models, and patient-derived organotypic tumor spheroids. SRSF10 was upregulated in various tumors and associated with poor prognosis. Moreover, SRSF10 positively regulated lactate production, and SRSF10/glycolysis/ histone H3 lysine 18 lactylation (H3K18la) formed a positive feedback loop in tumor cells. Increased lactate levels promoted M2 macrophage polarization, thereby inhibiting CD8+ T cell activity. Mechanistically, SRSF10 interacted with the 3'-untranslated region of MYB, enhancing MYB RNA stability, and subsequently upregulating key glycolysis-related enzymes including glucose transporter 1 (GLUT1), hexokinase 1 (HK1), lactate dehydrogenase A (LDHA), resulting in elevated intracellular and extracellular lactate levels. Lactate accumulation induced histone lactylation, which further upregulated SRSF10 expression. Additionally, lactate produced by tumors induced lactylation of the histone H3K18la site upon transport into macrophages, thereby activating transcription and enhancing pro-tumor macrophage activity. M2 macrophages, in turn, inhibited the enrichment of CD8+ T cells and the proportion of interferon-γ+CD8+ T cells in the tumor microenvironment (TME), thus creating an immunosuppressive TME. Clinically, SRSF10 could serve as a biomarker for assessing immunotherapy resistance in various solid tumors. Pharmacological targeting of SRSF10 with a selective inhibitor 1C8 enhanced the efficacy of programmed cell death 1 (PD-1) monoclonal antibodies (mAbs) in both murine and human preclinical models. The SRSF10/MYB/glycolysis/lactate axis is critical for triggering immune evasion and anti-PD-1 resistance. Inhibiting SRSF10 by 1C8 may overcome anti-PD-1 tolerance in HCC.

Autophagy-mediated ID1 turnover dictates chemo-resistant fate in ovarian cancer stem cells

BackgroundThe mechanisms enabling dynamic shifts between drug-resistant and drug-sensitive states in cancer cells are still underexplored. This study investigated the role of targeted autophagic protein degradation in regulating ovarian cancer stem cell (CSC) fate decisions and chemo-resistance.MethodsAutophagy levels were compared between CSC-enriched side population (SP) and non-SP cells (NSP) in multiple ovarian cancer cell lines using immunoblotting, immunofluorescence, and transmission electron microscopy. The impact of autophagy modulation on CSC markers and differentiation was assessed by flow cytometry, immunoblotting and qRT-PCR. In silico modeling and co-immunoprecipitation identified ID1 interacting proteins. Pharmacological and genetic approaches along with Annexin-PI assay, ChIP assay, western blotting, qRT-PCR and ICP-MS were used to evaluate effects on cisplatin sensitivity, apoptosis, SLC31A1 expression, promoter binding, and intracellular platinum accumulation in ID1 depleted backdrop. Patient-derived tumor spheroids were analyzed for autophagy and SLC31A1 levels.ResultsOvarian CSCs exhibited increased basal autophagy compared to non-CSCs. Further autophagy stimulation by serum-starvation and chemical modes triggered proteolysis of the stemness regulator ID1, driving the differentiation of chemo-resistant CSCs into chemo-sensitive non-CSCs. In silico modeling predicted TCF12 as a potent ID1 interactor, which was validated by co-immunoprecipitation. ID1 depletion freed TCF12 to transactivate the cisplatin influx transporter SLC31A1, increasing intracellular cisplatin levels and cytotoxicity. Patient-derived tumor spheroids exhibited a functional association between autophagy, ID1, SLC31A1, and platinum sensitivity.ConclusionsThis study reveals a novel autophagy-ID1-TCF12-SLC31A1 axis where targeted autophagic degradation of ID1 enables rapid remodeling of CSCs to reverse chemo-resistance. Modulating this pathway could counter drug resistance in ovarian cancer.

Enhancement of gemcitabine sensitivity in intrahepatic cholangiocarcinoma through Saikosaponin-a mediated modulation of the p-AKT/BCL-6/ABCA1 axis

BackgroundIntrahepatic cholangiocarcinoma (ICC) remains a significant challenge in cancer therapy, especially due to its resistance to established treatments like Gemcitabine, necessitating novel therapeutic approaches. MethodsThis study utilized Gemcitabine-resistant cell lines, patient-derived organotypic tumor spheroids (PDOTs), and patient-derived xenografts (PDX) to evaluate the effects of Saikosaponin-a (SSA) on ICC cellular proliferation, migration, apoptosis, and its potential synergistic interaction with Gemcitabine. Techniques such as transcriptome sequencing, Luciferase reporter assays, and molecular docking were employed to unravel the molecular mechanisms. ResultsSSA exhibited antitumor effects in both in vitro and PDX models, indicating its considerable potential for ICC treatment. SSA markedly inhibited ICC progression by reducing cellular proliferation, enhancing apoptosis, and decreasing migration and invasion. Crucially, it augmented Gemcitabine's efficacy by targeting the p-AKT/BCL6/ABCA1 signaling pathway. This modulation led to the downregulation of p-AKT and suppression of BCL6 transcriptional activity, ultimately reducing ABCA1 expression and enhancing chemosensitivity to Gemcitabine. Additionally, ABCA1 was validated as a predictive biomarker for drug resistance, with a direct correlation between ABCA1 expression levels and the IC50 values of various small molecule drugs in ICC gene profiles. ConclusionThis study highlights the synergistic potential of SSA combined with Gemcitabine in enhancing therapeutic efficacy against ICC and identifies ABCA1 as a key biomarker for drug responsiveness. Furthermore, the introduction of the novel PDOTs microfluidic model provides enhanced insights into ICC research. This combination strategy may provide a novel approach to overcoming treatment challenges in ICC.

Chimeric Antigen Receptor T Cell with an Inducible Caspase-9 Suicide Gene Eradicates Uveal Melanoma Liver Metastases via B7-H3 Targeting.

Uveal melanoma (UM) is the most common intraocular malignant tumor. Despite successful treatment of the primary tumor, about 50% of patients will recur with systemic diseases for which there are no effective treatment strategies. Here we investigated the preclinical efficacy of a chimeric antigen receptor (CAR) T-cell-based immunotherapy targeting B7-H3. B7-H3 expression on primary and metastatic human UM samples and cell lines was assessed by RNA sequencing, flow cytometry, and immunohistochemistry. Antitumor activity of CAR T cells targeting B7-H3 was tested in vitro with UM cell lines, patient-derived organotypic tumor spheroids from patients with metastatic UM, and in immunodeficient and humanized murine models. B7-H3 is expressed at high levels in >95% UM tumor cells in vitro and in vivo. We generated a B7-H3 CAR with an inducible caspase-9 (iCas9) suicide gene controlled by the chemical inducer of dimerization AP1903, which effectively kills UM cells in vitro and eradicates UM liver metastases in murine models. Delivery of iCas9.B7-H3 CAR T cells in experimental models of UM liver metastases demonstrates a durable antitumor response, even upon tumor rechallenge or in the presence of a significant metastatic disease burden. We demonstrate effective iCas9.B7-H3 CAR T-cell elimination in vitro and in vivo in response to AP1903. Our studies demonstrate more effective tumor suppression with iCas9.B7-H3 CAR T cells as compared to a B7-H3-targeted humanized monoclonal antibody. These studies support a phase I clinical trial with iCas9.B7-H3 CAR T cells to treat patients with metastatic UM.

Abstract LB218: Advanced ex vivo platform for drug response analysis: Evaluating the potent effects of NMC-521 mAb on mouse-and patient-derived organotypic tumor spheroids

Abstract In response to the high failure rate of new drugs in clinical trials, we have developed an innovative organotypic tumor spheroids platform, designed to mitigate the risks associated with advancing drugs to clinical stages. Utilizing patient-derived organotypic tumor spheroids (PDOTS), this platform uniquely captures both the phenotype and genotype of individual patient tumor microenvironments. This approach not only enhances the precision of preclinical models but also bridges the gap between laboratory research and clinical applicability. In this study, we assess the effectiveness of the first-in-class monoclonal antibody NMC-521 (NomoCan Pharmaceuticals, NY) using our ex vivo platform. Targeting the novel cancer-specific antigen NMC-1, NMC-521 exhibited significant growth inhibition of CT-26 tumors in syngeneic BALB/c mice, reducing tumor size by approximately 55% compared to the control. Similarly, in ex vivo settings with freshly excised CT-26 tumors (n=18), NMC-521 demonstrated a dose-dependent cytotoxic effect, achieving about a 65% reduction in tumor viability with an effective dose (ED50) of 10 µg/ml. Further insights were gained into NMC-521's mechanism of action using our ex vivo platform. The drug’s ability to induce tumor cell death in CT26 ex vivo was significantly reversed (p<0.01) when co-treated with α-NKG2D but not α-CD8, indicating a critical role for natural killer (NK) cells in its therapeutic effect. Complementing these findings, our analyses on freshly excised patient tumors (n=15) corroborated the cytotoxic effects of this drug on colorectal cancer but not to the same magnitude as in the CT-26 model. Furthermore, unlike the syngeneic murine tumor model, the response rate was (8 of 15 responsive patient tumors. Gene expression profiling indicated that NK cell-associated RNAs were elevated in NMC-521 treated PDOTS. Additionally, combination therapy studies using NMC-521 and nivolumab within our platform mirrored murine in vivo results, enhancing our understanding of the drug's potential in clinical settings. Intriguingly, an observed elevation in IL-15 levels in patient tumors treated with NMC-521 suggests an increased presence of NK cell activity when compared to treatments with nivolumab. This research underscores the potential of our organotypic tumor spheroids platform as a transformative tool in cancer drug development, offering an accurate and patient-specific method to evaluate new therapies, thereby increasing the likelihood of successful translation from the laboratory to patient care. Citation Format: Amir Aref, Alyssa Martin, Hamidreza Aboulkheyr Es, Patryk Krzesaj, Victor Adler, Kirti Khardenavis, Ehsan Sarafraz-Yazdi, Michael A. Perricone. Advanced ex vivo platform for drug response analysis: Evaluating the potent effects of NMC-521 mAb on mouse-and patient-derived organotypic tumor spheroids [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB218.

Abstract 4003: TBK1 inhibition enhances CAR-T cell efficacy against patient-derived organotypic tumor spheroids

Abstract Novel therapeutic strategies are needed to improve the efficacy of chimeric antigen receptor (CAR)-T cells in the treatment of solid tumors. Here, we set out to evaluate novel therapeutic strategies to improve the efficacy of B7-H3 (CD276) directed (B7-H3.CAR-T) using 3D microfluidic cultures of patient-derived organotypic tumor spheroids (PDOTS). PDOTS are generated from fresh patient tumor tissue and contain tumor cells, autologous immune cells and stromal cells, therefore recapitulating key features of the tumor microenvironment (TME), enabling the study of tumor-immune dynamics. We confirmed activity of B7-H3.CAR-T in PDOTS, although a strong correlation between B7-H3 expression and CAR-T efficacy was not observed. Mechanistic studies subsequently demonstrated dynamic upregulation of co-inhibitory receptors on CAR-T cells following target cell encounter leading to CAR-T cell dysfunction and limiting CAR-T efficacy in B7-H3 expressing tumors. PD-1 blockade restored CAR-T activity in monotypic and organotypic tumor spheroids with improved tumor control and upregulation of effector cytokines. Given the emerging role of TANK-binding kinase 1 (TBK1) as an immune evasion gene, we examined the effect of TBK1 inhibition on CAR-T efficacy. Similar to PD-1 blockade, TBK1 inhibition restored CAR-T activity in monotypic and organotypic tumor spheroids, prevented CAR-T cell dysfunction, and enhanced T cell proliferation. Inhibition or deletion of TBK1 also enhanced sensitivity of cancer cells to immune-mediated killing. Taken together, our results demonstrate the feasibility and utility of ex vivo profiling of CAR-T cells using PDOTS, and suggest that targeting TBK1 is a novel strategy to enhance CAR-T efficacy by overcoming tumor-intrinsic and -extrinsic resistance mechanisms. Citation Format: Luke Maggs, Yi Sun, Giulia Cattaneo, Marco Ventin, Feng Chen, Martin Q. Rasmussen, Xinhui Wang, Cristina R. Ferrone, Soldano Ferrone, Russell W. Jenkins. TBK1 inhibition enhances CAR-T cell efficacy against patient-derived organotypic tumor spheroids [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 4003.

Abstract 4252: Evaluation of NXI-101 in non-small cell lung cancer (NSCLC) using patient-derived organotypic tumor spheroids (PDOTS): Targeting a novel tumorigenic pathway

Abstract ONCOKINE-1 (OK-1), a soluble protein that is released by tumor cells, is implicated in the resistance of immunotherapy. Here we evaluated the efficacy of NXI-101, a monoclonal antibody that binds and neutralizes OK-1, in a model of patient-derived organotypic tumor spheroids (PDOTS) derived from non-small cell lung carcinoma (NSCLC) patients. NSCLC PDOTS were treated with NXI-101 and the effects of the drug were evaluated on day 3 post-treatment. Cytotoxicity was measured by Hoechst/Propidium Iodide staining and quantified by measuring the area-weighted percentage of cell death. Significant cytotoxicity was observed in 2 out of 10 patient tumors (20%) as a monotherapy and 4 out of 10 (40%) when used in combination with atezolizumab. The therapeutic response for both treatments was positively correlated (p<0.05) with the level of OK-1 expression, determined by immunohistochemistry using tissue sections taken on the day of tumor specimen collection. NXI-101 alone and in combination with atezolizumab had immunomodulatory effects that were associated with cytotoxic response. For example, transcriptomic analysis, Nanostring IO 360 Panel, indicated that the drug treatments resulted in the inhibition of TGF-β pathways and stimulated a number of immune pathways in 3 of the 4 responsive PDOTS. These pathways include interferon-α, JAK-STAT, and dendritic cell activation markers. We also observed evidence of activation of these same pathways in 2 of the 6 non-responsive PDOTS. These data support the prospects of NXI-101 as a first-in-class therapeutic for the treatment of NSCLC when used alone or in combination with an immune checkpoint inhibitor. Moreover, the findings highlight the PDOTS platform's substantial value in capturing patient-specific tumor response variability and providing robust support for the mechanistic evaluation of cancer therapeutics. Citation Format: Julia Vail, Hyung Gun Maeng, Je Woong Jang, Kyungjin Boo, Je-In Youn, Alyssa Martin, Aaron Goldman, Kyoung Wan Yoon, Michael A. Perricone. Evaluation of NXI-101 in non-small cell lung cancer (NSCLC) using patient-derived organotypic tumor spheroids (PDOTS): Targeting a novel tumorigenic pathway [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 4252.

Abstract 6733: Multiomics analysis of impact of CD8+ and other cell populations in STING agonist treated ex vivo mesothelioma samples

Abstract Background: Collective evidence highlights that agonism of the host STING pathway plays a critical role in eliciting robust and durable anti-tumor immunity. Dazostinag (TAK-676) is a novel systemically delivered STING agonist that ignites the innate immune system and mobilizes adaptive immunity. Preclinical studies with dazostinag demonstrated a strong, persistent CD8+ T cell anti-tumor response driven by innate immune derived type I IFN and pro-inflammatory cytokines. The role of CD8+ T cells in response to dazostinag was further supported by a previously demonstrated correlation between response and CD8+ T cell frequency in a patient-derived organotypic tumor spheroids (PDOTS) model of mesothelioma. Within the current work, we sought to determine the extent to which response to dazostinag in mesothelioma depends on CD8+ T cells versus the contribution of other immune cells. Methods: Surgical mesothelioma cases were collected along with clinicopathological variables at Brigham and Women’s Hospital under an IRB-approved protocol. PDOTS were generated as described previously. Ex vivo response was determined by fluorescent life/dead imaging, and orthogonally evaluated by multiplexed cytokine array, immunofluorescence, and flow cytometry; subset of tumors was studied using single cell RNA sequencing (scRNAseq). Results: Dazostinag-driven tumor cell killing was evaluated in 20 mesothelioma PDOTS. 11 samples were characterized as responders (R) with a cut-off of >30% reduction in live cell area; 9 as non-responders (NR). In 12 out of 20 PDOTS, CD8 neutralization effect was assessed: four were TAK-676 NR, and out of 8 R 4 had at least 20% killing abrogated by aCD8. Effect did not depend on the baseline amount of CD8+ T cells in the sample. scRNAseq analysis showed that R and NR T cells have different activation/exhaustion phenotypes and varying levels of interferon stimulated genes (ISG) in response to STING agonism. Other cell populations emerged as candidates for dazostinag resistance: NR cases carried remodeled immunosuppressive myeloid cells or matrix metalloproteinases-expressing fibroblasts. In general, myeloid cell abundance at baseline characterized by flow had a trend in negatively correlating with dazostinag response. Intrinsic expression of type I interferons shown by multiplexed cytokine array was linked to dazostinag sensitivity (R vs. NR IFN-β p=0.028; IFNα2a p=0.016) and can potentially be used as a predictor for response. Conclusion: We evaluated immune modulations in mesothelioma after treatment with a systemic STING agonist dazostinag using human tumor ex vivo culture. Innate interferon type I expression was higher in responding samples. TAK-676 efficacy was partially reduced in absence of effector lymphocytes, however other cells, such as immunosuppressive myeloid cells and fibroblasts, can have a negative impact on dazostinag response in mesothelioma. Citation Format: Elena Ivanova, Sung R. Park, Ari P. Zlota, Nathaniel Spicer, Minh Ha, Sophie Kivlehan, Iliana Gjeci, Simona Innocenti, Lauren Zasadil, Patrick Lizotte, Michael Y. Tolstorukov, Kai Ding, Adnan O. Abu-Yousif, Jeffrey Raizer, Vicky A. Appleman, Raphael Bueno, David A. Barbie, Cloud P. Paweletz. Multiomics analysis of impact of CD8+ and other cell populations in STING agonist treated ex vivo mesothelioma samples [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 6733.

Abstract 5235: Combination STING agonist and NK cellular therapy in patient derived organotypic tumor spheroids

Abstract Background: Increasing the immunogenicity of solid tumors may potentiate durable anti-tumor immunity. Targeting innate pattern recognition receptor signaling is a promising strategy to repolarizing the suppressive tumor immune microenvironment (TME). A potential synergistic approach is the addition of cellular therapy. Tumor models expressing high levels of endogenous STING, but where the pathway is not active, were considered for evaluating STING agonism as a potential intervention. Additionally, prior work has demonstrated that STING induction is toxic to T cells; however, natural killer (NK) cells are unaffected, due to their differential regulation of autophagy. Here we investigate the immunomodulatory properties of STING agonism alone and in combination with NK cells using short-term microfluidic culture of fresh patient-derived organotypic tumor spheroids (PDOTS). Methods: Surgical cases from Brigham and Women’s Hospital under an IRB-approved protocol were studied. PDOTS were generated as previously described. Ex vivo response was assessed by fluorescent live/dead imaging, immunofluorescence (IF), multiplexed cytokine array, and single cell RNA sequencing (scRNAseq). Baseline immune phenotypes were analyzed by FACS from single cells isolated during tumor sample preparation. Results: Twelve explants were studied. Two specimens were excluded from viability assessment due to excess of fibrotic material and low viability. Using a cut-off of -40%, three cases were characterized as responders (R) and seven as non-responders (NR). We observed significant induction of CXCL10 in all samples treated with STING agonist. IFN-β, IFN-γ, TNF-α, and MIP1-α were also consistently induced by STING agonist treatment. More detailed analysis of two samples by scRNAseq revealed a strong interferon stimulated genes (ISG) signature in STING agonist conditions; the cellular source of CXCL10 secretion in STING agonist treatment was tumor cells and fibroblasts. We also observed profound changes in myeloid biology, indicating that these cells polarized to a more pro-inflammatory and antigen-presenting phenotype with STING agonism. Interestingly, NK-based cell therapy added to PDOTS cultures displayed better persistence and enhanced effector function relative to endogenous NK cells, with and without STING agonism. Conclusions: Using tumor explants and a variety of orthogonal techniques, we investigated the response to STING agonism and NK cellular therapy ex vivo. Our results indicate that STING agonism remodels the TME, creating a more immune-permissive environment. STING agonism induces secretion of chemoattractant CXCL10 by tumor cells and fibroblasts. STING agonism does not abrogate NK cell effector function and therefore, may synergize with NK cell therapies. Citation Format: Patrick H. Lizotte, Elena Ivanova, Sung Park, Nathaniel Spicer, Sophie Kivlehan, Iliana Gjeci, Stefan Kiesgen, Vicky Appleman, LeeAnn Talarico, Michael Y. Tolstorukov, Raphael Bueno, David A. Barbie, Cloud P. Paweletz. Combination STING agonist and NK cellular therapy in patient derived organotypic tumor spheroids [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 5235.

Abstract 4073: Decoy-resistant IL-18 enhances checkpoint inhibitor combinations beyond anti-PD-1 in vitro and in vivo

Abstract Background: Interleukin-18 (IL18) is a proinflammatory cytokine that modulates both innate and adaptive immune responses. Historically, wild-type recombinant IL-18 has shown limited anti-tumor efficacy in preclinical models and clinical trials, likely due to upregulation of IL-18 binding protein (IL-18BP), a negative regulator of the IL-18 signaling axis. Accordingly, an engineered IL-18 cytokine capable of interacting with the IL-18 receptor, but resistant to IL-18BP interactions (i.e., “Decoy-Resistant IL-18”, DR-18), has demonstrated enhanced therapeutic potential in mouse tumor models, both as a single agent and in combination with anti-PD-1 [1, 2]. Here we evaluated murine DR-18 in combination with additional checkpoint inhibitors beyond anti-PD-1 in a set of mouse tumor models, and tested human DR-18 activity in vitro/ex vivo for activation of human immune cells and anti-tumor activity. Results: Treatment with mDR-18 elicited strong efficacy as a single agent and combination activity with immune checkpoint inhibitors (ICIs) across diverse syngeneic mouse models of solid tumors. As a single agent, mDR-18 demonstrated robust single agent activity in tumor growth inhibition for MC38 (>80%), CT26 (>60%) and B16-F10 (>55%). Combination treatment of mDR-18 with anti-PD-1, anti-CTLA-4, or anti-LAG-3 increased the efficacy for the MC38 (>85-95%), CT26 models (>80-85%), while the B16-F10 (>60%) showed smaller efficacy enhancement with the combinations. In vitro assays revealed human DR-18 (ST-067) activated immune cells and enhanced A549 tumor cell killing over 72hrs. Furthermore, ex vivo studies of 3D patient-derived tumor spheroids demonstrated that ST-067 impaired growth and increased immune cell infiltration, highlighting the potential of hDR-18 to enhance immune activity within the human tumor microenvironment. Conclusion: These studies expand the breadth of IL-18/checkpoint synergism beyond anti-PD-1 and confirm enhanced human immune response in vitro with the clinical candidate ST-067. Taken together, these findings strengthen the rationale for clinical combination of ST-067 with ICI agents in patients with solid tumors. 1.Zhou T, Damsky W, Weizman OE, et al. IL-18BP is a secreted immune checkpoint and barrier to IL-18 immunotherapy. Nature. 2020;583(7817):609-614. doi:10.1038/s41586-020-2422-62.Minnie SA, Waltner OG, Ensbey KS, et al. Depletion of exhausted alloreactive T cells enables targeting of stem-like memory T cells to generate tumor-specific immunity. Sci Immunol. 2022;7(76):eabo3420. doi:10.1126/sciimmunol.abo3420 Citation Format: Jeffrey N. Lindquist, Kai Qin, Aaron M. Ring, Hirdesh Uppal. Decoy-resistant IL-18 enhances checkpoint inhibitor combinations beyond anti-PD-1 in vitro and in vivo [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 4073.

Mesothelin CAR T Cells Secreting Anti-FAP/Anti-CD3 Molecules Efficiently Target Pancreatic Adenocarcinoma and its Stroma.

Targeting solid tumors with chimeric antigen receptor (CAR) T cells remains challenging due to heterogenous target antigen expression, antigen escape, and the immunosuppressive tumor microenvironment (TME). Pancreatic cancer is characterized by a thick stroma generated by cancer-associated fibroblasts (CAF), which may contribute to the limited efficacy of mesothelin-directed CAR T cells in early-phase clinical trials. To provide a more favorable TME for CAR T cells to target pancreatic ductal adenocarcinoma (PDAC), we generated T cells with an antimesothelin CAR and a secreted T-cell-engaging molecule (TEAM) that targets CAF through fibroblast activation protein (FAP) and engages T cells through CD3 (termed mesoFAP CAR-TEAM cells). Using a suite of in vitro, in vivo, and ex vivo patient-derived models containing cancer cells and CAF, we examined the ability of mesoFAP CAR-TEAM cells to target PDAC cells and CAF within the TME. We developed and used patient-derived ex vivo models, including patient-derived organoids with patient-matched CAF and patient-derived organotypic tumor spheroids. We demonstrated specific and significant binding of the TEAM to its respective antigens (CD3 and FAP) when released from mesothelin-targeting CAR T cells, leading to T-cell activation and cytotoxicity of the target cell. MesoFAP CAR-TEAM cells were superior in eliminating PDAC and CAF compared with T cells engineered to target either antigen alone in our ex vivo patient-derived models and in mouse models of PDAC with primary or metastatic liver tumors. CAR-TEAM cells enable modification of tumor stroma, leading to increased elimination of PDAC tumors. This approach represents a promising treatment option for pancreatic cancer.

Patient-derived tumor spheroid-induced angiogenesis preclinical platform for exploring therapeutic vulnerabilities in cancer

This study addresses the demand for research models that can support patient-treatment decisions and clarify the complexities of a tumor microenvironment by developing an advanced non-animal preclinical cancer model. Based on patient-derived tumor spheroids (PDTS), the proposed model reconstructs the tumor microenvironment with emphasis on tumor spheroid-driven angiogenesis. The resulting microfluidic chip system mirrors angiogenic responses elicited by PDTS, recapitulating patient-specific tumor conditions and providing robust, easily quantifiable outcomes. Vascularized PDTS exhibited marked angiogenesis and tumor proliferation on the microfluidic chip. Furthermore, a drug that targets the vascular endothelial growth factor receptor 2 (VEGFR2, ramucirumab) was deployed, which effectively inhibited angiogenesis and impeded tumor invasion. This innovative preclinical model was used for investigating distinct responses for various drug combinations, encompassing HER2 inhibitors and angiogenesis inhibitors, within the context of PDTS. This integrated platform could potentially advance precision medicine by harmonizing diverse data points within the tumor microenvironment with a focus on the interplay between cancer and the vascular system.

Patient-derived models facilitate precision medicine in liver cancer by remodeling cell-matrix interaction.

Liver cancer is an aggressive tumor originating in the liver with a dismal prognosis. Current evidence suggests that liver cancer is the fifth most prevalent cancer worldwide and the second most deadly type of malignancy. Tumor heterogeneity accounts for the differences in drug responses among patients, emphasizing the importance of precision medicine. Patient-derived models of cancer are widely used preclinical models to study precision medicine since they preserve tumor heterogeneity ex vivo in the study of many cancers. Patient-derived models preserving cell-cell and cell-matrix interactions better recapitulate in vivo conditions, including patient-derived xenografts (PDXs), induced pluripotent stem cells (iPSCs), precision-cut liver slices (PCLSs), patient-derived organoids (PDOs), and patient-derived tumor spheroids (PDTSs). In this review, we provide a comprehensive overview of the different modalities used to establish preclinical models for precision medicine in liver cancer.

Highly Mimetic Ex Vivo Lung-Cancer Spheroid-Based Physiological Model for Clinical Precision Therapeutics.

Lung cancer remains a major health problem despite the considerable research into prevention and treatment methods. Through a deeper understanding of tumors, patient-specific ex vivo spheroid models with high specificity can be used to accurately investigate the cause, metastasis, and treatment strategies for lung cancer. Biofabricate lung tumors are presented, consisting of patient-derived tumor spheroids, endothelial cells, and lung decellularized extracellular matrix, which maintain a radial oxygen gradient, as well as biophysicochemical behaviors of the native tumors for precision medicine. It is also demonstrated that the developed lung-cancer spheroid model reproduces patient responses to chemotherapeutics and targeted therapy in a co-clinical trial, with 85% accuracy, 86.7% sensitivity, and 80% specificity. RNA sequencing analysis validates that the gene expression in the spheroids replicates that in the patient's primary tumor. This model can be used as an ex vivo predictive model for personalized cancer therapy and to improve the quality of clinical care.

Abstract 3250: Targeting CD38 on exhausted T cells overcomes resistance to cancer immunotherapy

Abstract Despite the unprecedented success of immune checkpoint blockade (ICB) in melanoma and other cancers, therapeutic resistance remains a major challenge. CD38, an ecto-enzyme involved in NAD+ catabolism, is upregulated in dysfunctional/exhausted CD8+ T cells in human melanoma. As enrichment of dysfunctional CD8+ T cells is associated with lack of response to ICB, and NAD+ depletion via enhanced CD38 activity has been associated with diminished immune response, we hypothesized that CD38 might represent an attractive target to overcome resistance to ICB. While CD38 blockade has been shown to augment response to ICB in murine tumor models, the specific role of CD38 signaling in CD8 T cell exhaustion, and the therapeutic relevance of CD38 in human cancer have not been defined. Here, we confirm and extend previous observations that CD38 is enriched in exhausted CD8+ T cells during tumor progression and in response to ICB. Further, we demonstrate that disrupting CD38 signaling via neutralizing antibodies or pharmacological inhibition enhances response to ICB using established murine tumor models and patient-derived tumor explant models. Notably, we observed 54% response rate to combination PD-1/CD38 blockade using a cohort (n=35) of patient-derived organotypic tumor spheroids (PDOTS) from patients with ICB-refractory melanoma (11.4% response rate to single-agent PD-1 blockade). Supplementation of nicotinamide riboside (NR) to boost NAD+ levels mimicked the effects CD38 blockade/inhibition on PD-1 response, whereas FK866, an inhibitor of NAMPT a key step in NAD+ biosynthesis, blunted the response to combined PD-1/CD38 blockade, suggesting a major role for NAD+ in the efficacy of CD38 blockade/inhibition. Lastly, we demonstrate that in vitro CD38 inhibition/blockade in CD8+ T cells increases the levels of TCF7 (an effector/memory T cell transcription factor), decreases surface expression of co-inhibitory receptors (e.g., TIM-3, CD39, PD-1), and improves effector CD8 T cell function. Taken together, these data confirm a role for CD38 in CD8+ T cell exhaustion in melanoma and support further pre-clinical and clinical development of this novel therapeutic strategy to enhance anti-tumor immune responses. Citation Format: Or-Yam Revach, Angelina M. Cicerchia, Moshe Sade-Feldman, Seth Anderson, Robert T. Manguso, Nir Hacohen, Russell W. Jenkins. Targeting CD38 on exhausted T cells overcomes resistance to cancer immunotherapy [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 3250.

Abstract 3951: Unprecedented forward genetic screens reveal mechanisms of action, drug resistances, and hidden efficacies at amino acid resolution: combination of 5-ALA and Artesunate as a treatment option for glioblastoma multiforme

Abstract Forward genetic screens have revolutionized the field of target discovery, target deconvolution, and target validation, particularly in the cancer field. However, most approaches are limited to the interrogation of non-essential factors and identify gene networks rather than direct target structures. Inspired from work in the nematode C. elegans, we perform forward genetic screens based on chemical mutagenesis. This approach randomly introduces single nucleotide variants into the entire genome resulting in cell populations which carry substitutions in statistically more than 90% of all amino acids. Challenging such mutagenized cell populations with a drug candidate of interest, followed by next generation sequencing and analysis, reveals drug resistance mechanism, direct drug target interactions, and potential concealed efficacies. The alteration of single amino acids thereby allows interrogation of non-essential as well as most essential factors and increases screening resolution to the amino acid level. From such screens we inferred and tested a novel treatment option for glioblastoma multiforme. The natural compound Artemisinin and its derivative Artesunate are widely used anti-malarial drugs. Based on theircytotoxic activity, they are also tested as anti-cancer therapies, while the definite mechanism of action and critical host cell targets have remained largely elusive. Using forward genetic screening approaches, we demonstrate that porphyrin biosynthesis governs Artemisinin’s cytotoxicity. Genetic or pharmacological modulation of porphyrin production is sufficient to alter Artemisinin cytotoxicity in multiple eukaryotic cells, including human cancer cells. Combining Artesunate with 5-ALA treatment we translated the screening results to clinically relevant model systems of brain tumor development, such as glioblastomas in engineered cerebral organoids, patient-derived brain tumor spheroids, and orthotopic xenograft models. 5-ALA is a clinically approved photodynamic porphyrin enhancer and surgical fluorescence marker, which specifically marks tumorigenic brain areas. With this additional level of selectivity, we demonstrate a strong antineoplastic effect of the 5-ALA-Artesunatecombination in all tested model systems. These findings extend to the triple combination with temozolomide and urgently await further testing in clinical setups. Citation Format: Michael Orthofer, Jasmin Taubenschmid-Stowers, Marianna Rozsova, Anna Laemmerer, Daniela Loetsch, Johannes Gojo, Andreas Peyrl, Walter Berger, Ullrich Elling, Moritz Horn, Josef M. Penninger. Unprecedented forward genetic screens reveal mechanisms of action, drug resistances, and hidden efficacies at amino acid resolution: combination of 5-ALA and Artesunate as a treatment option for glioblastoma multiforme. [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 3951.

Translational Studies Using the MALT1 Inhibitor (S)-Mepazine to Induce Treg Fragility and Potentiate Immune Checkpoint Therapy in Cancer.

Regulatory T cells (Tregs) play a critical role in the maintenance of immune homeostasis but also protect tumors from immune-mediated growth control or rejection and pose a significant barrier to effective immunotherapy. Inhibition of MALT1 paracaspase activity can selectively reprogram immune-suppressive Tregs in the tumor microenvironment to adopt a proinflammatory fragile state, which offers an opportunity to impede tumor growth and enhance the efficacy of immune checkpoint therapy (ICT). We performed preclinical studies with the orally available allosteric MALT1 inhibitor (S)-mepazine as a single-agent and in combination with anti-programmed cell death protein 1 (PD-1) ICT to investigate its pharmacokinetic properties and antitumor effects in several murine tumor models as well as patient-derived organotypic tumor spheroids (PDOTS). (S)-mepazine demonstrated significant antitumor effects and was synergistic with anti-PD-1 therapy in vivo and ex vivo but did not affect circulating Treg frequencies in healthy rats at effective doses. Pharmacokinetic profiling revealed favorable drug accumulation in tumors to concentrations that effectively blocked MALT1 activity, potentially explaining preferential effects on tumor-infiltrating over systemic Tregs. The MALT1 inhibitor (S)-mepazine showed single-agent anticancer activity and presents a promising opportunity for combination with PD-1 pathway-targeted ICT. Activity in syngeneic tumor models and human PDOTS was likely mediated by induction of tumor-associated Treg fragility. This translational study supports ongoing clinical investigations (ClinicalTrials.gov Identifier: NCT04859777) of MPT-0118, (S)-mepazine succinate, in patients with advanced or metastatic treatment-refractory solid tumors.

Primary Human Pancreatic Cancer Cells Cultivation in Microfluidic Hydrogel Microcapsules for Drug Evaluation.

Chemotherapy is an essential postoperative treatment for pancreatic cancer, while due to the lack of effective drug evaluation platforms, the therapeutic outcomes are hampered by tumor heterogeneity among individuals. Here, a novel microfluidic encapsulated and integrated primary pancreatic cancer cells platform is proposed for biomimetic tumor 3D cultivation and clinical drug evaluation. These primary cells are encapsulated into hydrogel microcapsules of carboxymethyl cellulose cores and alginate shells based on a microfluidicelectrospraytechnique. Benefiting from the good monodispersity, stability, and precise dimensional controllability of the technology, the encapsulated cells can proliferate rapidly and spontaneously form 3D tumor spheroids with highly uniform size and good cell viability. By integrating these encapsulated tumor spheroids into a microfluidic chip with concentration gradient channels and culture chambers, dynamic and high-throughput drug evaluation of different chemotherapy regimens could be realized. It is demonstrated that different patient-derived tumor spheroids show different drug sensitivity on-chip, which is significantly consistent with the clinical follow-up study after the operation. The results demonstrate that the microfluidic encapsulated and integrated tumor spheroids platform has great application potential in clinical drug evaluation.

Combined mitoxantrone and anti-TGFβ treatment with PD-1 blockade enhances antitumor immunity by remodelling the tumor immune landscape in neuroblastoma

BackgroundPoor infiltration of functioning T cells renders tumors unresponsive to checkpoint-blocking immunotherapies. Here, we identified a combinatorial in situ immunomodulation strategy based on the administration of selected immunogenic drugs and immunotherapy to sensitize poorly T-cell-infiltrated neuroblastoma (NB) to the host antitumor immune response.Methods975A2 and 9464D NB cell lines derived from spontaneous tumors of TH-MYCN transgenic mice were employed to study drug combinations able of enhancing the antitumor immune response using in vivo and ex vivo approaches. Migration of immune cells towards drug-treated murine-derived organotypic tumor spheroids (MDOTS) were assessed by microfluidic devices. Activation status of immune cells co-cultured with drug-treated MDOTS was evaluated by flow cytometry analysis. The effect of drug treatment on the immune content of subcutaneous or orthotopic tumors was comprehensively analyzed by flow-cytometry, immunohistochemistry and multiplex immunofluorescence. The chemokine array assay was used to detect soluble factors released into the tumor microenvironment. Patient-derived organotypic tumor spheroids (PDOTS) were generated from human NB specimens. Migration and activation status of autologous immune cells to drug-treated PDOTS were performed.ResultsWe found that treatment with low-doses of mitoxantrone (MTX) recalled immune cells and promoted CD8+ T and NK cell activation in MDOTS when combined with TGFβ and PD-1 blockade. This combined immunotherapy strategy curbed NB growth resulting in the enrichment of a variety of both lymphoid and myeloid immune cells, especially intratumoral dendritic cells (DC) and IFNγ- and granzyme B-expressing CD8+ T cells and NK cells. A concomitant production of inflammatory chemokines involved in remodelling the tumor immune landscape was also detected. Interestingly, this treatment induced immune cell recruitment against PDOTS and activation of CD8+ T cells and NK cells.ConclusionsCombined treatment with low-dose of MTX and anti-TGFβ treatment with PD-1 blockade improves antitumor immunity by remodelling the tumor immune landscape and overcoming the immunosuppressive microenvironment of aggressive NB.