Human Ovarian Cancer Model Research Articles

A phase 1, first-in-human (FIH) study of adenovirally transduced autologous macrophages engineered to contain an anti-HER2 chimeric antigen receptor (CAR) in subjects with HER2 overexpressing solid tumors.

TPS668 Background: Adoptive T cell therapies have led to remarkable advances among patients with hematologic malignancies, but not in those with solid tumors. Macrophages are actively recruited into, and are abundantly present in the solid tumor microenvironment (sTME). Tumor- associated macrophages typically display immunosuppressive behavior, but when engineered to be proinflammatory, may be an ideal vector to administer adoptive cellular therapy in solid tumors. Furthermore, insertion of a CAR on the macrophages allow them to selectively recognize and phagocytose antigen overexpressing cancer cells. CAR macrophages reprogram the sTME and present neoantigens to T cells, leading to epitope spreading and immune memory. Human Epidermal Growth Factor Receptor 2 (HER2) overexpression promotes tumorigenesis in many cancers (Table). CT-0508 is a cell product comprised of autologous monocyte-derived pro-inflammatory macrophages expressing an anti-HER2 CAR. Pre-clinical studies have shown that CT-0508 induced targeted cancer cell phagocytosis while sparing normal cells, decreased tumor burden and prolonged survival in relevant models. CT-0508 cells were safe and effective in a semi-immunocompetent mouse model of human HER2 overexpressing ovarian cancer. Methods: This is a FIH Phase 1 study to evaluate safety, tolerability, cell manufacturing feasibility, trafficking and preliminary evidence of efficacy of investigational product CT-0508 in 18 subjects with locally advanced (unresectable) or metastatic solid tumors overexpressing HER2, who have failed available therapies, including anti-HER2 therapies when indicated. Filgrastim is being used to mobilize autologous hematopoietic progenitor cells for monocyte collection by apheresis. The CT-0508 CAR macrophage product is manufactured, prepared and cryopreserved from mobilized peripheral blood monocytes. Group 1 subjects receive CT-0508 infusion split over D1, 3 and 5. Dose limiting toxicities will be observed and addressed by a Safety Review Committee. Group 2 subjects will receive the full CT-0508 infusion on D1. Pre and post treatment biopsies and blood samples will be collected to investigate correlates of safety (immunogenicity), trafficking (PCR, RNA scope), CT-0508 persistence in blood and in the tumor, target antigen engagement, TME modulation (single cell RNA sequencing), immune response (TCR sequencing) and others. Clinical trial information: NCT04660929. [Table: see text]

ImmunoPET of Ovarian and Pancreatic Cancer with AR9.6, a Novel MUC16-Targeted Therapeutic Antibody.

Advances in our understanding of the contribution of aberrant glycosylation to the pro-oncogenic signaling and metastasis of tumor cells have reinvigorated the development of mucin-targeted therapies. Here, we validate the tumor-targeting ability of a novel monoclonal antibody (mAb), AR9.6, that binds MUC16 and abrogates downstream oncogenic signaling to confer a therapeutic response. The in vitro and ex vivo validation of the binding of AR9.6 to MUC16 was achieved via flow cytometry, radioligand binding assay (RBA), and immunohistochemistry (IHC). The in vivo MUC16 targeting of AR9.6 was validated by creating a 89Zr-labeled radioimmunoconjugate of the mAb and utilizing immunoPET and ex vivo biodistribution studies in xenograft models of human ovarian and pancreatic cancer. Flow cytometry, RBA, and IHC revealed that AR9.6 binds to ovarian and pancreatic cancer cells in an MUC16-dependent manner. The in vivo radiopharmacologic profile of 89Zr-labeled AR9.6 in mice bearing ovarian and pancreatic cancer xenografts confirmed the MUC16-dependent tumor targeting by the radioimmunoconjugate. Radioactivity uptake was also observed in the distant lymph nodes (LNs) of mice bearing xenografts with high levels of MUC16 expression (i.e., OVCAR3 and Capan-2). IHC analyses of these PET-positive LNs highlighted the presence of shed antigen as well as necrotic, phagocytized, and actively infiltrating neoplastic cells. The humanization of AR9.6 did not compromise its ability to target MUC16-expressing tumors. The unique therapeutic mechanism of AR9.6 combined with its excellent in vivo tumor targeting makes it a highly promising theranostic agent. huAR9.6 is poised for clinical translation to impact the management of metastatic ovarian and pancreatic cancers.

Abstract P001: The anti-angiogenic antibody BD0801 demonstrates better anti-tumor activity than bevacizumab and synergize with chemotherapies in multiple tumor models

Abstract Vascular endothelial growth factor (VEGF) and its receptor (VEGFR) play a fundamental role in tumor growth and angiogenesis. An increasing number of evidences have suggested enhanced anti-tumor activity when combining anti-angiogenic agents with chemotherapies in the clinic. To support the clinical development of BD0801, a humanized rabbit anti-VEGF monoclonal antibody, we assessed anti-tumor activities of BD0801 using a series of preclinical tumor mouse models including human ovarian cancer OVCAR-8 and SK-OV-3, human non-small cell lung cancer (NSCLC) NCI-H460, and human renal cancer Caki-1 models, with bevacizumab being used as a benchmark. We also investigated the pharmacological kinetics (PK) of BD0801 in cynomolgus monkeys. BD0801 or bevacizumab were intravenously injected into tumor bearing mice at 0.8 mg/kg, 2.5 mg/kg or 7.5 mg/kg twice a week. Combinations of chemotherapy and BD0801 or bevacizumab were also investigated in some of the tumor models. BD0801 presented more potent anti-tumor activities than bevacizumab in ovarian cancer, NSCLC and renal cancer mouse models in a dose-dependent manner. The tumor growth inhibition of BD0801 was 2-20%, 34-66%, or 32-84% when dosed at 0.8 mg/kg, 2.5 mg/kg or 7.5 mg/kg, respectively. Besides, combination of 2.5 mg/kg BD0801 and 10 mg/kg paclitaxel presented a statistically stronger antitumor activity in human ovarian cancer models compared to both single treatments (P<0.05). Combination of 2.5 mg/kg BD0801, 10 mg/kg paclitaxel, and 80 mg/kg carboplatin also presented a stronger antitumor activity than BD0801 or chemotherapy alone in the human NSCLC model. In cynomolgus monkeys received a single intravenous injection of BD0801 at 1.5, 5, and 15 mg/kg, the half-life (t1/2) of BD0801 was 39.4-142 h, the clearance (Cl) was 0.321-0.900 mL/h/kg, and the apparent volume of distribution (Vd) was 49.5-64.4 mL/kg. The peak concentrations (Cmax) of BD0801 were proportional to the doses administered. No difference on the PK parameters was observed between female and male monkeys. Taken together, this study has demonstrated BD0801 as a more potent molecule than bevacizumab in some preclinical tumor models, supporting further clinical development plans for BD0801, especially in combination with chemotherapeutics. Citation Format: Liting Xue, Jianxing Tang, Yuyin Ding, Lei Song, Shansen Xu, Yue Huang, Yan Wu, Wenjie Song, Renhong Tang, Wenqing Yang. The anti-angiogenic antibody BD0801 demonstrates better anti-tumor activity than bevacizumab and synergize with chemotherapies in multiple tumor models [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P001.

The effect of folate-appended methyl-β-cyclodextrin increases on survival rates in a peritoneal dissemination mouse models of human ovarian cancer

The effect of folate-appended methyl-β-cyclodextrin increases on survival rates in a peritoneal dissemination mouse models of human ovarian cancer

A HER2 Tri-Specific NK Cell Engager Mediates Efficient Targeting of Human Ovarian Cancer.

Simple SummaryHER2 is a marker known to be over-expressed on breast cancer, rendering it one of the most useful solid tumor targets for antibody-based therapies. Despite expression on ovarian cancer, results targeting HER2 in this setting have been disappointing, thus requiring more aggressive approaches. Natural killer (NK) cells are known as principal mediators of cancer cell killing, but cancer cells find ways to deter them. We devised a tri-specific biological drug containing antibody fragments that simultaneously binds NK cells and cancer cells and at the same time delivers a natural cytokine signal that triggers robust NK cell expansion. In vitro studies show the drug augments NK cell killing of a number of HER2-positive human cell lines, while enhancing NK cell activation and proliferation. Studies in mice engrafted with human ovarian cancer showed the drug has anti-tumor efficacy, clearly demonstrating its ability to bolster NK cells in their ability to contain tumor cell growth. Clinical studies validated antibodies directed against HER2, trastuzumab, and pertuzumab, as useful methodology to target breast cancer cases where HER2 is expressed. The hope was that HER2 targeting using these antibodies in ovarian cancer patients would prove useful as well, but clinical studies have shown lackluster results in this setting, indicating a need for a more comprehensive approach. Immunotherapy approaches stimulating the innate immune system show great promise, although enhancing natural killer (NK) function is not an established mainstream immunotherapy. This study focused on a new nanobody platform technology in which the bispecific antibody was altered to incorporate a cytokine. Herein we describe bioengineered CAM1615HER2 consisting of a camelid VHH antibody fragment recognizing CD16 and a single chain variable fragment (scFv) recognizing HER2 cross-linked by the human interleukin-15 (IL-15) cytokine. This tri-specific killer engager (TriKETM) showed in vitro prowess in its ability to kill ovarian cancer human cell lines. In addition, we demonstrated its efficacy in inducing potent anti-cancer effects in an in vivo xenograft model of human ovarian cancer engrafting both cancer cells and human NK cells. While previous approaches with trastuzumab and pertuzumab faltered in ovarian cancer, the hope is incorporating targeting and cytokine priming within the same molecule will enhance efficacy in this setting.

Graphene Nanoflake Antibody Conjugates for Multimodal Imaging of Tumors

Graphene‐based materials are promising scaffolds for use in the design of tailored‐made nanomedicines. Herein, the synthesis and characterization of a series of multifunctional carboxylated graphene nanoflakes (GNFs) conjugated to monoclonal antibodies (mAbs) for tumor‐specific binding and modulation of pharmacokinetics is presented. GNF–mAb constructs are coupled to a fluorophore (4,4‐difluoro‐4‐bora‐3a,4a‐diaza‐s‐indacene [BODIPY]) for applications in optical imaging, a paramagnetic Gd3+ complex, [GdDOTAGA(H2O)]−, and the hexadentate chelate desferrioxamine B (DFO) for radiolabeling with 89Zr4+ (t1/2 = 78.41 h) ions and applications in dual‐modality positron emission tomography/magnetic resonance imaging (PET/MRI). Experimental properties of [89Zr]GdDOTAGA–ZrDFO–GNF–trastuzumab are tested in extensive chemical, spectroscopic, radiochemical, and cellular assays in vitro, and assessment of the pharmacokinetics by PET imaging in mice bearing a human ovarian cancer model illustrates the potential of using GNF–mAbs to develop multifunctional PET/MRI probes.

Abstract CT204: A phase 1, first in human (FIH) study of adenovirally transduced autologous macrophages engineered to contain an anti-HER2 chimeric antigen receptor (CAR) in subjects with HER2 overexpressing solid tumors

Abstract Background: Adoptive T cell therapies have led to remarkable advances among patients with hematologic malignancies, but not in those with solid tumors. Macrophages are actively recruited into, and abundantly present in the solid tumor microenvironment (sTME). Tumor- associated macrophages typically evince immunosuppressive behavior, but when engineered to be proinflammatory, may be an ideal vector to administer adoptive cellular therapy in solid tumors. Furthermore, insertion of a CAR confers on the macrophages the ability to selectively recognize and phagocytose antigen overexpressing cancer cells. Additionally, CAR macrophages reprogram the sTME and present neoantigens to T cells, leading to epitope spreading and immune memory. Human Epidermal Growth Factor Receptor 2 (HER2) is overexpressed in many cancers, including but not limited to breast and gastroesophageal cancers. CT-0508 is a cell product comprised of autologous monocyte-derived pro-inflammatory macrophages expressing an anti-HER2 CAR. Pre-clinical studies have shown that CT-0508 induced targeted cancer cell phagocytosis while sparing normal cells, decreased tumor burden and prolonged survival in relevant models. CT-0508 cells were safe in a semi-immunocompetent mouse model of human HER2 overexpressing ovarian cancer. Methods: This is a FIH Phase 1 study to evaluate safety, tolerability, cell manufacturing feasibility, trafficking, and preliminary evidence of efficacy of investigational product CT-0508 in approximately 18 subjects with locally advanced (unresectable) or metastatic solid tumors overexpressing HER2 who have failed available therapies including anti-HER2 therapies when indicated. Filgrastim will be used to mobilize autologous hematopoietic progenitor cells for monocyte collection by apheresis. The CT-0508 CAR macrophage product will be manufactured, prepared and cryopreserved from mobilized peripheral blood monocytes. Group 1 subjects will receive CT-0508 infusion split over D1, 3 and 5. Subjects will be continually assessed for acute and cumulative toxicity. Dose limiting toxicities will be observed and addressed by a Safety Review Committee. Group 2 subjects will receive the full CT-0508 infusion on D1. Pre and post treatment biopsies and blood samples will be collected to investigate correlates of safety (immunogenicity), trafficking (PCR, RNA scope), persistence, target antigen engagement, TME modulation (single cell RNA sequencing), immune response (TCR sequencing) and others. Clinical trial registry number: NCT04660929 Citation Format: Joshua Bauml, Debora Barton, Amy Ronczka, Daniel Cushing, Michael Klichinsky, Elizabeth C. Dees. A phase 1, first in human (FIH) study of adenovirally transduced autologous macrophages engineered to contain an anti-HER2 chimeric antigen receptor (CAR) in subjects with HER2 overexpressing solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT204.

Therapeutic Overcoming of Cancer Stem Cell-Featured Chemo-Resistant Ovarian Cancer via Photodynamic Therapy and Cascadic Chemotherapy Combined Hyaluronan Nanoparticles

In this study, we designed combination cancer therapeutic hyaluronan nanoparticles (NIR-responsive ROS-generating pheophorbide A and ROS-cleavable thioketal-linked SN38; PheoA-SN38-HC NPs). And the combined therapeutic effects of PheoA-SN38-HC NPs were investigated against HEY-T30 human ovarian cancer (OC) model which highly co-expresses cancer stem cell (CSC) markers and exhibits strong chemo-resistance. Clinical Proteomic Tumor Analysis Consortium (CPTAC) data showed that the expression of CSC markers (CD44, ALDH1A1, and CD117) rather than folic acid receptor is highly associated with poor clinical outcomes in OC patients. Western assay, migration and colony forming assay proved chemo-resistant HEY-T30 cells overexpress CSC markers and much more invasive than other cancer cells. Synthesized NPs were ~250 nm and spherical by DLS and TEM analysis. FACS and microscopic analysis revealed the active targeting property of PheoA-SN38-HC NPs in CD44+ HEY-T30 cells. Moreover, synergistic effects of the combination therapy of photodynamic ROS generation and ROS-triggered SN38 release were clearly demonstrated with in vitro HEY-T30 cells and an in vivo xenograft mouse model. In particular, the paracrine cytotoxic effect of SN38 released by ROS-trigger suggested that combination design could compensate for the clinical limitation of photodynamic therapy.

A human multi-cellular model shows how platelets drive production of diseased extracellular matrix and tissue invasion

SummaryGuided by a multi-level “deconstruction” of omental metastases, we developed a tetra (four cell)-culture model of primary human mesothelial cells, fibroblasts, adipocytes, and high-grade serous ovarian cancer (HGSOC) cell lines. This multi-cellular model replicated key elements of human metastases and allowed malignant cell invasion into the artificial omental structure. Prompted by findings in patient biopsies, we used the model to investigate the role of platelets in malignant cell invasion and extracellular matrix, ECM, production. RNA (sequencing and quantitative polymerase-chain reaction), protein (proteomics and immunohistochemistry) and image analysis revealed that platelets stimulated malignant cell invasion and production of ECM molecules associated with poor prognosis. Moreover, we found that platelet activation of mesothelial cells was critical in stimulating malignant cell invasion. Whilst platelets likely activate both malignant cells and mesothelial cells, the tetra-culture model allowed us to dissect the role of both cell types and model the early stages of HGSOC metastases.

A phase 1, first in human study of adenovirally transduced autologous macrophages engineered to contain an anti-HER2 chimeric antigen receptor (CAR) in subjects with HER2 overexpressing solid tumors.

TPS2660 Background: Adoptive T cell therapies have led to remarkable advances among patients with hematologic malignancies, but not in those with solid tumors. Macrophages are actively recruited into, and abundantly present in the solid tumor microenvironment (sTME). Tumor- associated macrophages typically evince immunosuppressive behavior, but when engineered to be proinflammatory, may be an ideal vector to administer adoptive cellular therapy in solid tumors. Furthermore, insertion of a CAR confers on the macrophages the ability to selectively recognize and phagocytose antigen overexpressing cancer cells. Additionally, CAR macrophages reprogram the sTME and present neoantigens to T cells, leading to epitope spreading and immune memory. Human Epidermal Growth Factor Receptor 2 (HER2) is overexpressed in many cancers, including but not limited to breast and gastroesophageal cancers (Table). CT-0508 is a cell product comprised of autologous monocyte-derived pro-inflammatory macrophages expressing an anti-HER2 CAR. Pre-clinical studies have shown that CT-0508 induced targeted cancer cell phagocytosis while sparing normal cells, decreased tumor burden and prolonged survival in relevant models. CT-0508 cells were safe and effective in a semi-immunocompetent mouse model of human HER2 overexpressing ovarian cancer. Methods: This is a FIH phase 1 study to evaluate safety, tolerability, cell manufacturing feasibility, trafficking, and preliminary evidence of efficacy of investigational product CT-0508 in approximately 18 subjects with locally advanced (unresectable) or metastatic solid tumors overexpressing HER2 who have failed available therapies including anti-HER2 therapies when indicated. Filgrastim will be used to mobilize autologous hematopoietic progenitor cells for monocyte collection by apheresis. The CT-0508 CAR macrophage product will be manufactured, prepared and cryopreserved from mobilized peripheral blood monocytes. The study is enrolling Group 1 subjects, who will receive CT-0508 infusion split over D1, 3 and 5. Subjects will be continually assessed for acute and cumulative toxicity. Dose limiting toxicities will be observed and addressed by a Safety Review Committee. Group 2 subjects will follow, and will receive the full CT-0508 infusion on D1. Pre and post treatment biopsies and blood samples will be collected to investigate correlates of trafficking, persistence, TME modulation, immune response and safety. Clinical trial information: NCT04660929. [Table: see text]

SynNotch CAR circuits enhance solid tumor recognition and promote persistent antitumor activity in mouse models.

The first clinically approved engineered chimeric antigen receptor (CAR) T cell therapies are remarkably effective in a subset of hematological malignancies with few therapeutic options. Although these clinical successes have been exciting, CAR T cells have hit roadblocks in solid tumors that include the lack of highly tumor-specific antigens to target, opening up the possibility of life-threatening "on-target/off-tumor" toxicities, and problems with T cell entry into solid tumor and persistent activity in suppressive tumor microenvironments. Here, we improve the specificity and persistent antitumor activity of therapeutic T cells with synthetic Notch (synNotch) CAR circuits. We identify alkaline phosphatase placental-like 2 (ALPPL2) as a tumor-specific antigen expressed in a spectrum of solid tumors, including mesothelioma and ovarian cancer. ALPPL2 can act as a sole target for CAR therapy or be combined with tumor-associated antigens such as melanoma cell adhesion molecule (MCAM), mesothelin, or human epidermal growth factor receptor 2 (HER2) in synNotch CAR combinatorial antigen circuits. SynNotch CAR T cells display superior control of tumor burden when compared to T cells constitutively expressing a CAR targeting the same antigens in mouse models of human mesothelioma and ovarian cancer. This was achieved by preventing CAR-mediated tonic signaling through synNotch-controlled expression, allowing T cells to maintain a long-lived memory and non-exhausted phenotype. Collectively, we establish ALPPL2 as a clinically viable cell therapy target for multiple solid tumors and demonstrate the multifaceted therapeutic benefits of synNotch CAR T cells.

Abstract PO042: Microfluidic modeling of tumor-macrophage signaling in ovarian cancer

Abstract In ovarian cancer, the presence of macrophages in the tumor microenvironment (TME) has been associated with poor clinical outcomes. Understanding mechanisms of macrophage recruitment and signaling with tumor cells in the TME may uncover novel therapeutic targets to block the pro-tumor effects of macrophages and improve patient outcomes. Several tumor secreted factors, such as mCSF, CCL2, IL8, and periostin have been implicated in the recruitment of macrophages to the tumor site. However, previous studies of macrophage recruitment have utilized culture systems that fail to recapitulate TME complexity. Therefore, a 3D physiologically relevant microfluidic platform was used in this work that can accurately control cell-cell interactions. Our microfluidic design incorporates chemokine concentration gradients and allows for the study of the spatiotemporal macrophage infiltration dynamics towards ovarian cancer cells using live cell microscopy. We first studied the abilities of a panel of high grade serous ovarian cancer models comprised of established cancer cell lines (murine ID8 and human CaOV3, OHSAHO, OVCAR8) and patient-derived high-grade serous ovarian cancer xenografts (4 PDX models) to recruit macrophages via microfluidic and collagen-droplet based 3D assays. The presence of tumor cells enhanced macrophage infiltration into collagen 3-fold after 48 hours. We found that ovarian cancer models that efficiently recruited macrophages expressed higher levels of mCSF, CCL2, and IL8 cytokines. Furthermore, tumor cell secreted factors more potently increased macrophage recruitment compared to chemotactic gradients of CCL2 and mCSF, indicating a complex signaling network between tumor cells and macrophages. RAW264.7 murine macrophages additionally induced resistance to cisplatin-induced cell death in ID8 cells proportional to increasing macrophage:tumor cell ratios. We also studied the ability of CSF1R inhibition to block macrophage infiltration. Treatment with BLZ945, a potent CSF1R inhibitor that is evaluated in clinical trials, effectively blocked the recruitment of the RAW264.7 macrophages towards ID8 ovarian cancer cells. We subsequently characterized the attachment and invasion profiles of the human and murine ovarian cancer models in syngeneic and immunocompromised xenografts in vivo. We found that tumor cells attached and invaded the ovaries, abdominal organs, and fatty tissue. In a preliminary analysis, one of the PDX models that efficiently recruited macrophages also formed invasive implants, while another PDX model with poor macrophage infiltration did not exhibit invasive implant formation. This work demonstrates the capability of a microfluidic platform to model macrophage infiltration in ovarian cancer. In ongoing studies using this microfluidic platform we are investigating the effects of chemotherapy-induced changes in the tumor cell secretome on macrophage infiltration and the resulting effects on tumor cell chemotherapy sensitivity. Citation Format: Alexis L. Scott, Oluwadamilola Ayoola, Ioannis K. Zervantonakis. Microfluidic modeling of tumor-macrophage signaling in ovarian cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference on the Evolving Tumor Microenvironment in Cancer Progression: Mechanisms and Emerging Therapeutic Opportunities; in association with the Tumor Microenvironment (TME) Working Group; 2021 Jan 11-12. Philadelphia (PA): AACR; Cancer Res 2021;81(5 Suppl):Abstract nr PO042.

Abstract OT-28-06: A phase 1, first in human study of adenovirally transduced autologous macrophages engineered to contain an anti-HER2 chimeric antigen receptor in subjects with HER2 overexpressing solid tumors

Abstract Adoptive T cell therapies have led to remarkable advances among patients with hematologic malignancies, but not in those with solid tumors. Macrophages are actively recruited into and more abundantly present in the tumor microenvironment (TME) as compared to T cells. Tumor- associated macrophages (TAMs), typically evince immunosuppressive behavior, but when engineered to be proinflammatory, may be an ideal vector to administer adoptive cellular therapy in solid tumors. Furthermore, insertion of a CAR confers on the macrophages the ability to selectively recognize and phagocytose antigen overexpressing cancer cells. CAR macrophages can also potentially interact with, stimulate, and present neoantigens to T cells. Human Epidermal Growth Factor Receptor 2 (HER2) is overexpressed in many cancers, including but not limited to breast and gastroesophageal cancers (Table 1). CT-0508 is a cell product comprised of autologous monocyte-derived pro-inflammatory macrophages expressing an anti-HER2 CAR. In vitro and in vivo studies have shown that CT-0508 leads to cancer cell phagocytosis sparing normal cells, decreased tumor burden and prolonged survival. CT-0508 cells were safe in a semi-immunocompetent mouse model of human HER2 overexpressing ovarian cancer. This is a FIH Phase 1 study to evaluate safety, tolerability, cell manufacturing feasibility, trafficking, and preliminary evidence of efficacy of investigational product CT-0508 on approximately 18 subjects with locally advanced (unresectable) or metastatic solid tumors overexpressing HER2 who have failed available therapies including anti-HER2 therapies when indicated.Filgrastim, will be used to mobilize autologous hematopoietic progenitor cells for monocyte collection by apheresis. CT-0508 cell product will be manufactured, prepared and cryopreserved. Group 1 will receive CT-0508 infusion split over D1, 3 and 5. Subjects will be continually assessed for acute and cumulative toxicity. Dose limiting toxicities will be observed and addressed by a Safety Review Committee. Group 2 will receive the full CT-0508 infusion on D1. Pre and post treatment biopsies and blood samples will be collected to investigate correlates of trafficking, persistence, TME modulation, immune response and safety. Citation Format: Natalie Grover, Debora Barton, Amy Ronczka, Joshua Bauml. A phase 1, first in human study of adenovirally transduced autologous macrophages engineered to contain an anti-HER2 chimeric antigen receptor in subjects with HER2 overexpressing solid tumors [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr OT-28-06.

Abstract 4515: The anti-CD47 antibody SRF231 increases anti-tumor activity of standard of care chemotherapy in platinum-resistant PDX models of ovarian cancer

Abstract Background: CD47 is a type I integral membrane protein expressed on multiple human tumors, including ovarian cancer, and modulates cell processes such as cell migration, adhesion, T-cell function, and cell death via interaction with multiple ligands. Interaction of CD47 with SIRPα expressed on myeloid cells results in an inhibitory “don't eat me” signal that prevents phagocytosis of CD47-expressing cancer cells. Enhancement of the anti-tumor activity of chemotherapy has also been reported with CD47 antagonists. We investigated the effects of combining SRF231, an investigational fully human IgG4 antibody, with chemotherapy in models of human ovarian cancer. Methods: Expression of CD47 in 8 established platinum-resistant PDX models of ovarian cancer was measured by immunohistochemistry with the anti-CD47 antibody SP279. SRF231-mediated phagocytosis of ovarian cancer cell lines was assessed using a macrophage coculture system. Cell death from combining SRF231 with either doxorubicin or platinum in vitro was assessed by Annexin V assay. The activity of SRF231 combined with doxorubicin in vivo was compared to isotype control, SRF231, or doxorubicin monotherapy in an ovarian cancer subcutaneous xenograft model, OVCAR3. Additionally, the activity of SRF231 combined with platinum was compared to isotype control, SRF231, or platinum monotherapy in two luciferase-expressing intraperitoneal PDX ovarian cancer models, as measured by bioluminescent imaging. Results: CD47 expression was high across all 8 PDX models. SRF231 induced phagocytosis of ovarian cancer cell lines by human monocyte-derived macrophages. SRF231 potentiated doxorubicin- or oxaliplatin-mediated cell death in Jurkat cells in Annexin V assays. In the OVCAR3 xenograft model, the combination of SRF231 and doxorubicin resulted in significant tumor growth inhibition and improved survival compared to isotype control, SRF231 monotherapy, or doxorubicin monotherapy. In the PDX model DF216, which demonstrates no evidence of monotherapy response to SRF231, combination of SRF231 and carboplatin resulted in tumor regression with significantly enhanced anti-tumor activity compared to carboplatin or SRF231 monotherapy, as well as to isotype control. Similarly, in the PDX model DF86, where SRF231 demonstrates modest monotherapy activity, combination SRF231 and carboplatin resulted in tumor regression and significant increase in anti-tumor activity compared to carboplatin or SRF231 monotherapies. Conclusion: Anti-CD47 directed therapy with SRF231, a fully human antibody, demonstrated the ability to significantly increase the anti-tumor activity of standard chemotherapies in xenograft and platinum-resistant PDX models of ovarian cancer. Further exploration of combining anti-CD47 and platinum regimens in ovarian cancer is warranted. Citation Format: Joyce F. Liu, Kshama A. Doshi, Benjamin H. Lee, Marisa O. Peluso, Li Zhang, Shan Zhou, Qing Zeng, Stephen Wang, Paul T. Kirschmeier, Cam A. Tran, Cloud Paweletz, Matthew Rausch, Alison M. Paterson, Prafulla C. Gokhale, Ursula A. Matulonis. The anti-CD47 antibody SRF231 increases anti-tumor activity of standard of care chemotherapy in platinum-resistant PDX models of ovarian cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4515.

Natural compound Tan-I enhances the efficacy of Paclitaxel chemotherapy in ovarian cancer.

BackgroundPaclitaxel is a widely used clinical first line chemotherapy drug for ovarian carcinoma. Tanshinone I (Tan-I) is one of the vital fat-soluble components, which derived from Chinese herbal medicine, Salvia miltiorrhiza Bunge. Herein, we evaluated whether Tan-I could enhance the efficacy of ovarian cancer to chemotherapy of Paclitaxel.MethodsOvarian cancer cells A2780 and ID-8 were exposed with Tan-I (4.8 µg/mL), Paclitaxel (0.1 µg/mL), or Tan-I combination with Paclitaxel for 24 hours. The cell proliferation was analyzed by CCK8 and EdU staining. Cell apoptosis was analyzed by the TUNEL assay and flow cytometry. The protein levels were determined by western blot. Cell migration was analyzed by Transwell and wound healing. Cell senescence was analyzed by senescence-associated b-galactosidase staining. Antitumor activity was analyzed by a subcutaneous tumor xenograft model of human ovarian cancer in nude mice. The protein expression and apoptosis level of tumor tissues were analyzed by immunohistochemistry and TUNEL staining.ResultsTan-I treatment significantly elevated the Paclitaxel-cause reduction of A2780 and ID-8 cell proliferation and cell migration. Tan-I combination with Paclitaxel promotes apoptosis of cancer cells by promoting Bax expression and Bcl-2 expression. Besides, Tan-I treatment can notably increase Paclitaxel-inducing cell senescence by promoting DNA damage and senescence-associated proteins such as p21 and p16. Furthermore, the result of the transplanted tumor model indicated that Tan-I combination with Paclitaxel could inhibit tumor growth in vivo by inhibiting cell proliferation and inducing cell apoptosis.ConclusionsNatural compound Tan-I enhances the efficacy of ovarian cancer to Paclitaxel chemotherapy. The results will help to supply the potential clinical use of ovarian carcinoma cells.

Tanshinone I attenuates the malignant biological properties of ovarian cancer by inducing apoptosis and autophagy via the inactivation of PI3K/AKT/mTOR pathway.

ObjectivesTanshinone I (Tan‐I) is one of the vital fatsoluble monomer components, which extracted from Chinese medicinal herb Salvia miltiorrhiza Bunge. It has been shown that Tan‐I exhibited anti‐tumour activities on different types of cancers. However, the underlying mechanisms by which Tan‐Ⅰ regulates apoptosis and autophagy in ovarian cancer remain unclear. Thus, this study aimed to access the therapy effect of Tan‐Ⅰ and the underlying mechanisms.MethodsOvarian cancer cells A2780 and ID‐8 were treated with different concentrations of Tan‐Ⅰ (0, 1.2, 2.4, 4.8 and 9.6 μg/mL) for 24 hours. The cell proliferation was analysed by CCK8 assay, EdU staining and clone formation assay. Apoptosis was assessed by the TUNEL assay and flow cytometry. The protein levels of apoptosis protein (Caspase‐3), autophagy protein (Beclin1, ATG7, p62 and LC3II/LC3I) and PI3K/AKT/mTOR pathway were determined by Western blot. Autophagic vacuoles in cells were observed with LC3 dyeing using confocal fluorescent microscopy. Anti‐tumour activity of Tan‐Ⅰ was accessed by subcutaneous xeno‐transplanted tumour model of human ovarian cancer in nude mice. The Ki67, Caspase‐3 level and apoptosis level were analysed by immunohistochemistry and TUNEL staining.ResultsTan‐Ⅰ inhibited the proliferation of ovarian cancer cells A2780 and ID‐8 in a dose‐dependent manner, based on CCK8 assay, EdU staining and clone formation assay. In additional, Tan‐Ⅰ induced cancer cell apoptosis and autophagy in a dose‐dependent manner in ovarian cancer cells by TUNEL assay, flow cytometry and Western blot. Tan‐Ⅰ significantly inhibited tumour growth by inducing cell apoptosis and autophagy. Mechanistically, Tan‐Ⅰ activated apoptosis‐associated protein Caspase‐3 cleavage to promote cell apoptosis and inhibited PI3K/AKT/mTOR pathway to induce autophagy.ConclusionsThis is the first evidence that Tan‐Ⅰ induced apoptosis and promoted autophagy via the inactivation of PI3K/AKT/mTOR pathway on ovarian cancer and further inhibited tumour growth, which might be considered as effective strategy.

Methods for Evaluation of a Snake Venom-Derived Disintegrin in Animal Models of Human Cancer.

Integrin targeting has been shown to be an effective approach for anticancer therapy. We engineered a recombinant disintegrin, vicrostatin (VCN), that binds with high affinity and specificity to the Arg-Gly-Asp (RGD) class of integrins, including αvβ3, αvβ5, and α5β1, involved in tumor invasion and metastasis. We used three different delivery modalities to examine anticancer activity of VCN in mouse models of human ovarian cancer, glioma, and prostate cancer. A female mouse model was used to examine the treatment of established ovarian cancer (OC) using VCN delivered intraperitoneally (IP) weekly either in saline or impregnated in a viscoelastic gel. SKOV3luc cells (a human OC cell line) were directly injected IP into immunodeficient mice. We also examined the antitumor activity of radioiodinated VCN delivered intravenously in a human glioma model in nude mice. We evaluated the effectiveness of 131I-VCN in combination with the DNA alkylating agent temozolomide in limiting glioma growth. Finally, treatment of a bone metastatic model of human prostate cancer (PC) in immunodeficient mice was examined using a liposomal formulation of VCN (LVCN) delivered intravenously. Human PC cells were suspended in a solution of Matrigel and injected into the left tibia of immunodeficient mice. Diameters of both the left and right (control) tibias were measured by caliper repeatedly after VCN treatment was initiated.

Conventional and Chemically Programmed Asymmetric Bispecific Antibodies Targeting Folate Receptor 1.

T-cell engaging bispecific antibodies (biAbs) can mediate potent and specific tumor cell eradication in liquid cancers. Substantial effort has been invested in expanding this concept to solid cancers. To explore their utility in the treatment of ovarian cancer, we built a set of asymmetric biAbs in IgG1-like format that bind CD3 on T cells with a conventional scFv arm and folate receptor 1 (FOLR1) on ovarian cancer cells with a conventional or a chemically programmed Fab arm. For avidity engineering, we also built an asymmetric biAb format with a tandem Fab arm. We show that both conventional and chemically programmed CD3 × FOLR1 biAbs exert specific in vitro and in vivo cytotoxicity toward FOLR1-expressing ovarian cancer cells by recruiting and activating T cells. While the conventional T-cell engaging biAb was curative in an aggressive mouse model of human ovarian cancer, the potency of the chemically programmed biAb was significantly boosted by avidity engineering. Both conventional and chemically programmed CD3 × FOLR1 biAbs warrant further investigation for ovarian cancer immunotherapy.

Proteomic analysis reveals a role for PAX8 in peritoneal colonization of high grade serous ovarian cancer that can be targeted with micelle encapsulated thiostrepton.

High grade serous ovarian cancer (HGSOC) is the fifth leading cause of cancer deaths among women yet effective targeted therapies against this disease are limited. The heterogeneity of HGSOC, including few shared oncogenic drivers and origination from both the fallopian tube epithelium (FTE) and ovarian surface epithelium (OSE), has hampered development of targeted drug therapies. PAX8 is a lineage-specific transcription factor expressed in the FTE that is also ubiquitously expressed in HGSOC where it is an important driver of proliferation, migration, and cell survival. PAX8 is not normally expressed in the OSE, but it is turned on after malignant transformation. In this study, we use proteomic and transcriptomic analysis to examine the role of PAX8 leading to increased migratory capabilities in a human ovarian cancer model, as well as in tumor models derived from the OSE and FTE. We find that PAX8 is a master regulator of migration with unique downstream transcriptional targets that are dependent on the cell’s site of origin. Importantly, we show that targeting PAX8, either through CRISPR genomic alteration or through drug treatment with micelle encapsulated thiostrepton, leads to a reduction in tumor burden. These findings suggest PAX8 is a unifying protein driving metastasis in ovarian tumors that could be developed as an effective drug target to treat HGSOC derived from both the OSE and FTE.

Abstract 1761: Inhibition of PI3K/AKT/mTOR signaling by a dual PI3K/mTOR inhibitor (LY3023414) potentiates the antitumor efficacy of the Chk1 inhibitor prexasertib (LY2606368) in models of human high-grade serous ovarian cancer (HGSOC)

Abstract HGSOC (characterized by defects in DNA damage repair and high levels of genomic instability and DNA replication stress) is the most lethal gynecological malignancy in the United States. The current treatment options for HGSOC are limited and new approaches are needed. Checkpoint kinase 1 (Chk1), a key protein kinase that regulates the cell cycle, DNA damage and replication stress response, has emerged as an attractive target for anti-cancer therapy. Prexasertib, an ATP-competitive inhibitor of Chk1, is being evaluated in a Phase 2 trial sponsored by NCI (NCT02203513); and the preliminary data showed encouraging results in patients with wild-type BRCA HGSOC. PI3K/AKT/mTOR pathway plays key roles in cancer cell survival, homologous recombination repair and drug resistance. Our previous data showed the expression level of genes related to PI3K/AKT signaling is elevated in prexasertib-resistant TNBC patient-derived xenograft (PDX) tumors. In this study we explored whether the PI3K/AKT/mTOR pathway is involved in prexasertib response of HGSOC and evaluated the combination effect of prexasertib with a PI3K/mTOR inhibitor (LY3023414) on HGSOC in vitro and in vivo. Data from 24 n=1 HGSOC PDX tumors indicated that the tumors with high phospho-AKT were resistant to prexasertib. The PI3K/AKT/mTOR signaling (including p70S6K and S6RP) was activated and correlated with the increased DNA damage (γH2AX) in HGSOC cell lines treated with prexasertib. These data suggest that the PI3K/AKT signaling is associated with prexasertib resistance and the cell survival response to DNA damage induced by prexasertib; and provide the scientific rational for a prexasertib/LY3023414 combination. Indeed the prexasertib/LY3023414 combination induced synergistic or additive inhibition on cell proliferation and colony formation in multiple HGSOC cell lines. This combination enhanced replication stress (phospho-RPA32), DNA damage (γH2AX), S phase arrest and cell death (cleaved PARP and sub-G1) in HGSOC Ovcar-8 cells when compared with single agent activity. Combination efficacy was further tested in HGSOC OV-90 and Cov504 xenograft models. Prexasertib induced tumor inhibition by 58.8% in OV-90 and tumor regression by 37.3% in Cov504, and LY3023414 induced tumor inhibition by 43.37% and 66% in OV-90 and Cov504 tumors, respectively. Prexasertib/LY3023414 combination resulted in tumor regression by 8.9% and 73.7% in OV-90 and Cov504 tumors, respectively, and significantly (p<0.001) enhanced efficacy when compared to singe agent. Taken together, these data support a potential combination strategy of Chk1 inhibitor prexasertib with a PI3K/mTOR inhibitor LY3023414 to treat HGSOC patients. The safety of this combination is being assessed in an ongoing Phase 1b clinical trial (NCT02124148). Citation Format: Jack Dempsey, Greg Donoho, Philip Iversen, Jennifer Stephens, Ann McNulty, Ricardo Martinez, Christoph Reinhard, Louis Stancato, Aimee Lin, Wenjuan Wu. Inhibition of PI3K/AKT/mTOR signaling by a dual PI3K/mTOR inhibitor (LY3023414) potentiates the antitumor efficacy of the Chk1 inhibitor prexasertib (LY2606368) in models of human high-grade serous ovarian cancer (HGSOC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1761.