Dual-inhibition of NAMPT and PAK4 induces anti-tumor effects in 3D-spheroids model of platinum-resistant ovarian cancer

Ovarian cancer follows a characteristic progression pattern, forming multiple tumor masses enriched with cancer stem cells (CSCs) within the abdomen. Most patients develop resistance to standard platinum-based drugs, necessitating better treatment approaches. Targeting CSCs by inhibiting NAD+ synthesis has been previously explored. Nicotinamide phosphoribosyltransferase (NAMPT), which is the rate limiting enzyme in the salvage pathway for NAD+ synthesis is an attractive drug target in this pathway. KPT-9274 is an innovative drug targeting both NAMPT and p21 activated kinase 4 (PAK4). However, its effectiveness against ovarian cancer has not been validated. Here, we show the efficacy and mechanisms of KPT-9274 in treating 3D-cultured spheroids that are resistant to platinum-based drugs. In these spheroids, KPT-9274 not only inhibited NAD+ production in NAMPT-dependent cell lines, but also suppressed NADPH and ATP production, indicating reduced mitochondrial function. It also downregulated of inflammation and DNA repair-related genes. Moreover, the compound reduced PAK4 activity by altering its mostly cytoplasmic localization, leading to NAD+-dependent decreases in phosphorylation of S6 Ribosomal protein, AKT, and β-Catenin in the cytoplasm. These findings suggest that KPT-9274 could be a promising treatment for ovarian cancer patients who are resistant to platinum drugs, emphasizing the need for precision medicine to identify the specific NAD+ producing pathway that a tumor relies upon before treatment.

UGDH promotes tumor-initiating cells and a fibroinflammatory tumor microenvironment in ovarian cancer

BACKGROUND

Epithelial ovarian cancer (EOC) is a global health burden, with the poorest five-year survival rate of the gynecological malignancies due to diagnosis at advanced stage and high recurrence rate. Recurrence in EOC is driven by the survival of chemoresistant, stem-like tumor-initiating cells (TICs) that are supported by a complex extracellular matrix and immunosuppressive microenvironment. To target TICs to prevent recurrence, we identified genes critical for TIC viability from a whole genome siRNA screen. A top hit was the cancer-associated, proteoglycan subunit synthesis enzyme UDP-glucose dehydrogenase (UGDH).

METHODS

Immunohistochemistry was used to characterize UGDH expression in histological and molecular subtypes of EOC. EOC cell lines were subtyped according to the molecular subtypes and the functional effects of modulating UGDH expression in vitro and in vivo in C1/Mesenchymal and C4/Differentiated subtype cell lines was examined.

RESULTS

High UGDH expression was observed in high-grade serous ovarian cancers and a distinctive survival prognostic for UGDH expression was revealed when serous cancers were stratified by molecular subtype. High UGDH was associated with a poor prognosis in the C1/Mesenchymal subtype and low UGDH was associated with poor prognosis in the C4/Differentiated subtype. Knockdown of UGDH in the C1/mesenchymal molecular subtype reduced spheroid formation and viability and reduced the CD133 + /ALDH high TIC population. Conversely, overexpression of UGDH in the C4/Differentiated subtype reduced the TIC population. In co-culture models, UGDH expression in spheroids affected the gene expression of mesothelial cells causing changes to matrix remodeling proteins, and fibroblast collagen production. Inflammatory cytokine expression of spheroids was altered by UGDH expression. The effect of UGDH knockdown or overexpression in the C1/ Mesenchymal and C4/Differentiated subtypes respectively was tested on mouse intrabursal xenografts and showed dynamic changes to the tumor stroma. Knockdown of UGDH improved survival and reduced tumor burden in C1/Mesenchymal compared to controls.

CONCLUSIONS

These data show that modulation of UGDH expression in ovarian cancer reveals distinct roles for UGDH in the C1/Mesenchymal and C4/Differentiated molecular subtypes of EOC, influencing the tumor microenvironmental composition. UGDH is a strong potential therapeutic target in TICs, for the treatment of EOC, particularly in patients with the mesenchymal molecular subtype.

Overcoming the challenges of drug development in platinum-resistant ovarian cancer

The definition of "platinum-resistant ovarian cancer" has evolved; it now also reflects cancers for which platinum treatment is no longer an option. Standard of care for platinum-resistant ovarian cancer is single-agent, non-platinum chemotherapy with or without bevacizumab, which produces modest response rates, with the greatest benefits achieved using weekly paclitaxel. Several recent phase 3 trials of pretreated patients with prior bevacizumab exposure failed to meet their primary efficacy endpoints, highlighting the challenge in improving clinical outcomes among these patients. Combination treatment with antiangiogenics has improved outcomes, whereas combination strategies with immune checkpoint inhibitors have yielded modest results. Despite extensive translational research, there has been a lack of reliable and established biomarkers that predict treatment response in platinum-resistant ovarian cancer. Additionally, in the platinum-resistant setting, implications for the time between the penultimate dose of platinum therapy and platinum retreatment remain an area of debate. Addressing the unmet need for an effective treatment in the platinum-resistant setting requires thoughtful clinical trial design based on a growing understanding of the disease. Recent cancer drug approvals highlight the value of incorporating molecular phenotypes to better define patients who are more likely to respond to novel therapies. Clinical trials designed per the Gynecologic Cancer InterGroup recommendations-which advocate against relying solely upon the platinum-free interval-will help advance our understanding of recurrent ovarian cancer response where platinum rechallenge in the platinum-resistant setting may be considered. The inclusion of biomarkers in clinical trials will improve patient stratification and potentially demonstrate correlations with biomarker expression and duration of response. With the efficacy of antibody-drug conjugates shown for the treatment of some solid and hematologic cancers, current trials are evaluating the use of various novel conjugates in the setting of platinum-resistant ovarian cancer. Emerging novel treatments coupled with combination trials and biomarker explorations offer encouraging results for potential strategies to improve response rates and prolong progression-free survival in this population with high unmet need. This review outlines existing data from contemporary clinical trials of patients with platinum-resistant ovarian cancer and suggests historical synthetic benchmarks for non-randomized trials.

A Single-Arm, Open-Label Phase II Study of ONC201 in Recurrent/Refractory Metastatic Breast Cancer and Advanced Endometrial Carcinoma

BACKGROUND

ONC201 is a small molecule that can cause nonapoptotic cell death through loss of mitochondrial function. Results from the phase I/II trials of ONC201 in patients with refractory solid tumors demonstrated tumor responses and prolonged stable disease in some patients.

METHODS

This single-arm, open-label, phase II clinical trial evaluated the efficacy of ONC201 at the recommended phase II dose (RP2D) in patients with recurrent or refractory metastatic breast or endometrial cancer. Fresh tissue biopsies and blood were collected at baseline and at cycle 2 day 2 for correlative studies.

RESULTS

Twenty-two patients were enrolled; 10 patients with endometrial cancer, 7 patients with hormone receptor-positive breast cancer, and 5 patients with triple-negative breast cancer. The overall response rate was 0%, and the clinical benefit rate, defined by complete response (CR) + partial response (PR) + stable disease (SD), was 27% (n = 3/11). All patients experienced an adverse event (AE), which was primarily low grade. Grade 3 AEs occurred in 4 patients; no grade 4 AEs occurred. Tumor biopsies did not show that ONC201 consistently induced mitochondrial damage or alterations in tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) or the TRAIL death receptors. ONC201 treatment caused alterations in peripheral immune cell subsets.

CONCLUSION

ONC201 monotherapy did not induce objective responses in recurrent or refractory metastatic breast or endometrial cancer at the RP2D dose of 625 mg weekly but had an acceptable safety profile (ClinicalTrials.gov Identifier: NCT03394027).

Patients' perspectives on prenatal screening results that suggest maternal cancer: A qualitative analysis

OBJECTIVE

To explore patient perspectives after receiving non-invasive prenatal testing (NIPT) results that suggest maternal cancer.

METHODS

Individuals who received non-reportable or discordant NIPT results during pregnancy and enrolled in a study were interviewed prior to and after receiving the outcome of their clinical evaluation for cancer. Interviews were independently coded by two researchers and analyzed thematically.

RESULTS

Forty-nine participants were included. Three themes were identified: 1) limited pre-test awareness of maternal incidental findings caused considerable confusion for participants, whose initial concerns focused on their babies; 2) providers' communication influenced how participants perceived their risk of cancer and the need to be evaluated; and 3) participants perceived value in receiving maternal incidental findings from NIPT despite any stress it caused during their pregnancy.

CONCLUSION

Participants viewed the ability to detect occult malignancy as an added benefit of NIPT and felt strongly that these results should be disclosed. Obstetric providers need to be aware of maternal incidental findings from NIPT, inform pregnant people of the potential to receive these results during pre-test counseling, and provide accurate and objective information during post-test counseling.

CLINICAL TRIAL REGISTRATION

Incidental Detection of Maternal Neoplasia Through Non-Invasive Cell-Free DNA Analysis (IDENTIFY), a Natural History Study, NCT4049604.

NF-κB Signaling Modulates miR-452-5p and miR-335-5p Expression to Functionally Decrease Epithelial Ovarian Cancer Progression in Tumor-Initiating Cells

Epithelial ovarian cancer (EOC) remains the fifth leading cause of cancer-related death in women worldwide, partly due to the survival of chemoresistant, stem-like tumor-initiating cells (TICs) that promote disease relapse. We previously described a role for the NF-κB pathway in promoting TIC chemoresistance and survival through NF-κB transcription factors (TFs) RelA and RelB, which regulate genes important for the inflammatory response and those associated with cancer, including microRNAs (miRNAs). We hypothesized that NF-κB signaling differentially regulates miRNA expression through RelA and RelB to support TIC persistence. Inducible shRNA was stably expressed in OV90 cells to knockdown RELA or RELB; miR-seq analyses identified differentially expressed miRNAs hsa-miR-452-5p and hsa-miR-335-5p in cells grown in TIC versus adherent conditions. We validated the miR-seq findings via qPCR in TIC or adherent conditions with RELA or RELB knocked-down. We confirmed decreased expression of hsa-miR-452-5p when either RELA or RELB were depleted and increased expression of hsa-miR-335-5p when RELA was depleted. Either inhibiting miR-452-5p or mimicking miR-335-5p functionally decreased the stem-like potential of the TICs. These results highlight a novel role of NF-κB TFs in modulating miRNA expression in EOC cells, thus opening a better understanding toward preventing recurrence of EOC.

Abstract 3781: NF-κB classical and alternative signaling differentially regulate miRNA expression in ovarian cancer

The NF-κB signaling pathway has been shown to contribute to epithelial ovarian cancer (EOC) through its classical and alternative pathways, characterized by the RelA and RelB transcription factors respectively. Previous studies have highlighted the role of RelA in sustaining the proliferative cancer cell population, while RelB aids in promoting the survival of chemoresistant, stem-like tumor-initiating cells (TICs) that promote disease relapse. In further characterizing the downstream effects of NF-κB signaling on EOC, we hypothesize NF-κB signaling differentially regulates the expression of several microRNAs (miRNAs) to promote TIC survival and proliferation through its classical and alternative pathways. miRNAs comprise a subset of small, noncoding RNAs that regulate gene expression, making them amenable for therapeutic targeting. Inducible shRNA stably expressed in OV90 EOC cells to knockdown RelA or RelB were analyzed by miR-seq to identify the differential expression of miRNAs in cells grown in TIC vs adherent (adh) conditions. Several miRNAs were differentially expressed in these conditions with RelA or RelB knockdown; we identified and validated the expression of two candidate miRNAs: hsa-miR-452-5p and hsa-miR-335-5p. We observed the decreased expression of hsa-miR-452-5p when either RelA or RelB is knocked down, while also observing the increased expression of hsa-miR-335-5p when RelA is knocked down. By inhibiting miR-452-5p in conjunction with disrupting NF-κB activity, we found changes in cell viability, sphere formation, and expression of the stem cell marker ALDH. Understanding the role of miRNA signaling in the context of NF-κB will better define the transcriptional roles of RelA and RelB in EOC. Ongoing work will further characterize the downstream targets of these miRNAs as potential therapeutic targets.

Citation Format: Rahul D. Kamdar, Brittney S. Harrington, Soumya Korrapati, Emma Attar, Nathan Wong, Carrie D. House, Christina M. Annunziata. NF-κB classical and alternative signaling differentially regulate miRNA expression in ovarian cancer. [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 3781.

Abstract 5654: A therapeutic humanized anti-carcinoma monoclonal antibody (mAb) NEO-201 can also target human granulocytic myeloid-derived suppressor cells (gMDSCs) and regulatory T (Tregs) cells

Background: NEO-201 is a humanized IgG1 mAb reactive against multiple human cancers but not against most normal epithelial tissues. NEO-201 binds to core 1 or extended core 1 O-glycans expressed by its target cells, including neutrophils, various carcinomas, and some human hematological malignancies. NEO-201 can mediate antitumor activity through antibody-dependent cellular cytotoxicity (ADCC), complement dependent cytotoxicity (CDC), and blockade of the CEACAM5/CEACAM1 ICI pathway. A previous study using flow cytometry demonstrated that NEO-201+/CD4+ T cells were also CD25+/CD127−/Foxp3+/CD15s+ using PBMCs from healthy donors (HD). NEO-201 can kill these Treg cells through CDC in vitro. NEO-201 does not bind to the majority of CD4+ T cells and to other immune subsets. Human gMDSCs are increased in cancer patients and are a population of immature MDSCs deriving from immature neutrophils and alternative activation of mature neutrophils. gMDSC are characterized by HLA-DR−, CD11b+, CD33+, CD15+phenotype.We have shown that NEO-201 recognizes and kill human neutrophils through ADCC. This current investigation was designed to evaluate whether NEO-201 can target and mediate ADCC activity against human gMDSCs.

Methods: gMDSCs were generated from human neutrophils from 5 HD isolated using EasySepTM direct human neutrophil isolation kit. Isolated neutrophils were cultured in complete RPMI1640 medium supplemented with human GM-CSF and human IL-6 for 7 days. Phenotypic analysis by flow cytometry was performed on the generated gMDSCs using NEO-201 and mAbs against human CD33, HLA-DR, CD15, CD14, CD66b. Flow cytometry based ADCC assay was performed using gMDSCs stained with both CD33 and HLA-DR as target. PBMCs from a separate HD were used as effectors at different E:T ratios. The ADCC activity of NEO-201 was evaluated comparing the percentage of CD33+/HLA-DR− viable cells in gMDSCs incubated with medium alone to the percentage of CD33+/HLA-DR− viable cells incubated with PBMCs alone and with PBMCs plus NEO-201.

Results: Flow cytometry analysis revealed that gMDSCs can be generated from human neutrophils after 7 days of culture with GM-CSF and IL-6 and that they express the following phenotype: HLA-DR−/CD33+/CD15+/CD14−/CD66b+. NEO-201 bound to the majority of these gMDSCs. NEO-201 was functional in mediating ADCC to kill these gMDSCs.

Conclusion: This study demonstrated that NEO-201 can be used to identify and kill suppressive gMDSCs in addition to Treg cells. Depletion of suppressive Tregs and gMDSCs in the TME could be an effective strategy to prevent hyperprogressive disease when anti-PD-1 is used in cancer immunotherapy. These data support the rationale for the ongoing phase II clinical trial using NEO-201 in combination with pembrolizumab in checkpoint refractory patients with metastatic solid tumors.

Citation Format: Massimo Fantini, Christina M. Annunziata, Philip M. Arlen, Kwong Y. Tsang. A therapeutic humanized anti-carcinoma monoclonal antibody (mAb) NEO-201 can also target human granulocytic myeloid-derived suppressor cells (gMDSCs) and regulatory T (Tregs) cells. [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 5654.

First-in-human phase 1 clinical trial of anti-core 1 O-glycans targeting monoclonal antibody NEO-201 in treatment-refractory solid tumors

BACKGROUND

NEO201 is a humanized IgG1 monoclonal antibody (mAb) generated against tumor-associated antigens from patients with colorectal cancer. NEO-201 binds to core 1 or extended core 1 O-glycans expressed by its target cells. Here, we present outcomes from a phase I trial of NEO-201 in patients with advanced solid tumors that have not responded to standard treatments.

METHODS

This was a single site, open label 3 + 3 dose escalation clinical trial. NEO-201 was administered intravenously every two weeks in a 28-day cycle at dose level (DL) 1 (1 mg/kg), DL 1.5 (1.5 mg/kg) and DL 2 (2 mg/kg) until dose limiting toxicity (DLT), disease progression, or patient withdrawal. Disease evaluations were conducted after every 2 cycles. The primary objective was to assess the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D) of NEO-201. The secondary objective was to assess the antitumor activity by RECIST v1.1. The exploratory objectives assessed pharmacokinetics and the effect of NEO-201 administration on immunologic parameters and their impact on clinical response.

RESULTS

Seventeen patients (11 colorectal, 4 pancreatic and 2 breast cancers) were enrolled; 2 patients withdrew after the first dose and were not evaluable for DLT. Twelve of the 15 patients evaluable for safety discontinued due to disease progression and 3 patients discontinued due to DLT (grade 4 febrile neutropenia [1 patient] and prolonged neutropenia [1 patient] at DL 2, and grade 3 prolonged (> 72 h) febrile neutropenia [1 patient] at DL 1.5). A total of 69 doses of NEO-201 were administered (range 1-15, median 4). Common (> 10%) grade 3/4 toxicities occurred as follows: neutropenia (26/69 doses, 17/17 patients), white blood cell decrease (16/69 doses, 12/17 patients), lymphocyte decrease (8/69 doses, 6/17 patients). Thirteen patients were evaluable for disease response; the best response was stable disease (SD) in 4 patients with colorectal cancer. Analysis of soluble factors in serum revealed that a high level of soluble MICA at baseline was correlated with a downregulation of NK cell activation markers and progressive disease. Unexpectedly, flow cytometry showed that NEO-201 also binds to circulating regulatory T cells and reduction of the quantities of these cells was observed especially in patients with SD.

CONCLUSIONS

NEO-201 was safe and well tolerated at the MTD of 1.5 mg/kg, with neutropenia being the most common adverse event. Furthermore, a reduction in the percentage of regulatory T cells following NEO-201 treatment supports our ongoing phase II clinical trial evaluating the efficiency of the combination of NEO-201 with the immune checkpoint inhibitor pembrolizumab in adults with treatment-resistant solid tumors.

TRIAL REGISTRATION

NCT03476681 . Registered 03/26/2018.

SMAC Mimetics Synergistically Cooperate with HDAC Inhibitors Enhancing TNF-α Autocrine Signaling

The overexpression of inhibitor of apoptosis (IAP) proteins is strongly related to poor survival of women with ovarian cancer. Recurrent ovarian cancers resist apoptosis due to the dysregulation of IAP proteins. Mechanistically, Second Mitochondrial Activator of Caspases (SMAC) mimetics suppress the functions of IAP proteins to restore apoptotic pathways resulting in tumor death. We previously conducted a phase 2 clinical trial of the single-agent SMAC mimetic birinapant and observed minimal drug response in women with recurrent ovarian cancer despite demonstrating on-target activity. Accordingly, we performed a high-throughput screening matrix to identify synergistic drug combinations with birinapant. SMAC mimetics in combination with an HDAC inhibitor showed remarkable synergy and was, therefore, selected for further evaluation. We show here that this synergy observed both in vitro and in vivo results from multiple convergent pathways to include increased caspase activation, HDAC inhibitor-mediated TNF-α upregulation, and alternative NF-kB signaling. These findings provide a rationale for the integration of SMAC mimetics and HDAC inhibitors in clinical trials for recurrent ovarian cancer where treatment options are still limited.

Intraperitoneal Monocytes plus IFNs as a Novel Cellular Immunotherapy for Ovarian Cancer: Mechanistic Characterization and Results from a Phase I Clinical Trial

PURPOSE

Ovarian cancer is the most lethal gynecologic cancer and intrinsically resistant to checkpoint immunotherapies. We sought to augment innate immunity, building on previous work with IFNs and monocytes.

PATIENTS AND METHODS

Preclinical experiments were designed to define the mechanisms of cancer cell death mediated by the combination of IFNs α and γ with monocytes. We translated these preclinical findings into a phase I trial of autologous IFN-activated monocytes administered intraperitoneally to platinum-resistant or -refractory ovarian cancer patients.

RESULTS

IFN-treated monocytes induced caspase 8-dependent apoptosis by the proapoptotic TRAIL and mediated by the death receptors 4 and 5 (DR4 and DR5, respectively) on cancer cells. Therapy was well tolerated with evidence of clinical activity, as 2 of 9 evaluable patients had a partial response by RECIST criteria, and 1 additional patient had a CA-125 response. Upregulation of monocyte-produced TRAIL and cytokines was confirmed in peripheral blood. Long-term responders had alterations in innate and adaptive immune compartments.

CONCLUSIONS

Given the mechanism of cancer cell death, and the acceptable tolerability of the clinical regimen, this platform presents a possibility for future combination therapies to augment anticancer immunity. See related commentary by Chow and Dorigo, p. 299.

Flotillin-2 regulates epidermal growth factor receptor activation, degradation by Cbl-mediated ubiquitination, and cancer growth

Epidermal growth factor receptor (EGFR) signaling is frequently dysregulated in various cancers. The ubiquitin ligase Casitas B-lineage lymphoma proto-oncogene (Cbl) regulates degradation of activated EGFR through ubiquitination and acts as an adaptor to recruit proteins required for trafficking. Here, we used stable isotope labeling with amino acids in cell culture mass spectrometry to compare Cbl complexes with or without epidermal growth factor (EGF) stimulation. We identified over a hundred novel Cbl interactors, and a secondary siRNA screen found that knockdown of Flotillin-2 (FLOT2) led to increased phosphorylation and degradation of EGFR upon EGF stimulation in HeLa cells. In PC9 and H441 cells, FLOT2 knockdown increased EGF-stimulated EGFR phosphorylation, ubiquitination, and downstream signaling, reversible by EGFR inhibitor erlotinib. CRISPR knockout (KO) of FLOT2 in HeLa cells confirmed EGFR downregulation, increased signaling, and increased dimerization and endosomal trafficking. Furthermore, we determined that FLOT2 interacted with both Cbl and EGFR. EGFR downregulation upon FLOT2 loss was Cbl dependent, as coknockdown of Cbl and Cbl-b restored EGFR levels. In addition, FLOT2 overexpression decreased EGFR signaling and growth. Overexpression of wildtype (WT) FLOT2, but not the soluble G2A FLOT2 mutant, inhibited EGFR phosphorylation upon EGF stimulation in HEK293T cells. FLOT2 loss induced EGFR-dependent proliferation and anchorage-independent growth. Lastly, FLOT2 KO increased tumor formation and tumor volume in nude mice and NSG mice, respectively. Together, these data demonstrated that FLOT2 negatively regulated EGFR activation and dimerization, as well as its subsequent ubiquitination, endosomal trafficking, and degradation, leading to reduced proliferation in vitro and in vivo.

Identification of the O-Glycan Epitope Targeted by the Anti-Human Carcinoma Monoclonal Antibody (mAb) NEO-201

Simple Summary

Glycosylation is an important post-translational modification made on mammalian proteins and lipids. In cancer cells, the disruption of several glycosylation patterns, such as the O-glycosylation, has been observed. The expression of incomplete/truncated O-glycans in cancer cells occurs in both solid and liquid tumors and is correlated with poor prognosis and tumor progression. The employment of monoclonal antibodies (mAbs) targeting truncated O-glycans in cancer cells could serve as an effective strategy to counteract tumor growth. In previous studies, we reported that the IgG1-humanized mAb NEO-201 binds specifically to tumor-associated variants of CEACAM5 and CEACAM6 expressed by colon, ovarian, pancreatic, non-small cell lung, head and neck, cervical, uterine and breast cancers but is not reactive against most normal tissues. Since CEACAMs are highly glycosylated proteins, in this article, we evaluated whether the epitope recognized by NEO-201 is an O-glycan. This study demonstrated that NEO-201 binds to core 1 O-glycans and targets and kills cancer cells expressing core 1 and extended core 1 O-glycans. Usually, GalNAc residue can be added on to threonine and serine to form O-glycans, suggesting that NEO-201 binds to core 1 and extended core 1 O-glycans attached to any protein carrying amino acid regions containing serine and threonine

Abstract

Truncated O-glycans expressed in cancer cells support tumor progression, and they may serve as potential targets to improve the monitoring and treatment of cancers. Previously, we reported that NEO-201 binds to several tumors expressing tumor-associated CEACAM5 and CEACAM6 variants but does not bind to those expressed in healthy tissues. This specific binding may be associated with the presence of truncated O-glycans attached on the protein sequence of these variants. To evaluate the glycosylation pattern targeted by NEO-201 we performed an O-glycan array consisting of 94 O-glycans. O-glycan profiles were elucidated from the human pancreatic cancer cell line CFPAC-1, human hematological neoplastic cells (HL-60, U937, K562) and human neutrophils. The O-glycan array analysis showed that NEO-201 interacts with core 1-4 O-glycans and that the binding to a specific core 1 O-glycan was the strongest. The O-glycan profiling of the NEO-201-reactive cells CFPAC-1, HL-60, U937 and human neutrophils showed that cells recognized by NEO-201 express mostly core 1 and/or extended core 1 O-glycans. In addition, NEO-201 mediates antibody-dependent cell-mediated cytotoxicity (ADCC) against tumor cells expressing core 1 or extended core 1 O-glycan profiles. These results demonstrated that NEO-201 binds to core 1 and extended core 1 O-glycans expressed in its target cells. Since GalNAc residue can be added onto threonine and serine to form O-glycans, it is very likely that NEO-201 recognizes these O-glycans attached to any protein with amino acid regions containing serine and threonine.

Mitochondrial Matrix Protease ClpP Agonists Inhibit Cancer Stem Cell Function in Breast Cancer Cells by Disrupting Mitochondrial Homeostasis

Mitochondria are multifaceted organelles which are important for bioenergetics, biosynthesis and signaling in metazoans. Mitochondrial functions are frequently altered in cancer to promote both the energy and the necessary metabolic intermediates for biosynthesis required for tumor growth. Cancer stem cells (CSCs) contribute to chemotherapy resistance, relapse, and metastasis. Recent studies have shown that while non-stem, bulk cancer cells utilize glycolysis, breast CSCs are more dependent on oxidative phosphorylation (OxPhos) and therefore targeting mitochondria may inhibit CSC function. We previously reported that small molecule ONC201, which is an agonist for the mitochondrial caseinolytic protease (ClpP), induces mitochondrial dysfunction in breast cancer cells. In this study, we report that ClpP agonists inhibit breast cancer cell proliferation and CSC function in vitro and in vivo. Mechanistically, we found that OxPhos inhibition downregulates multiple pathways required for CSC function, such as the mevalonate pathway, YAP, Myc, and the HIF pathway. ClpP agonists showed significantly greater inhibitory effect on CSC functions compared with other mitochondria-targeting drugs. Further studies showed that ClpP agonists deplete NAD(P)+ and NAD(P)H, induce redox imbalance, dysregulate one-carbon metabolism and proline biosynthesis. Downregulation of these pathways by ClpP agonists further contribute to the inhibition of CSC function. In conclusion, ClpP agonists inhibit breast CSC functions by disrupting mitochondrial homeostasis in breast cancer cells and inhibiting multiple pathways critical to CSC function.

Significance

ClpP agonists disrupt mitochondrial homeostasis by activating mitochondrial matrix protease ClpP. We report that ClpP agonists inhibit cell growth and cancer stem cell functions in breast cancer models by modulating multiple metabolic pathways essential to cancer stem cell function.

Development and Characterization of an Anti-Cancer Monoclonal Antibody for Treatment of Human Carcinomas

NEO-201 is an IgG1 humanized monoclonal antibody (mAb) that binds to tumor-associated variants of carcinoembryonic antigen-related cell adhesion molecule (CEACAM)-5 and CEACAM-6. NEO-201 reacts to colon, ovarian, pancreatic, non-small cell lung, head and neck, cervical, uterine and breast cancers, but is not reactive against most normal tissues. NEO-201 can kill tumor cells via antibody-dependent cell-mediated cytotoxicity (ADCC) and complement dependent cytotoxicity (CDC) to directly kill tumor cells expressing its target. We explored indirect mechanisms of its action that may enhance immune tumor killing. NEO-201 can block the interaction between CEACAM-5 expressed on tumor cells and CEACAM-1 expressed on natural killer (NK) cells to reverse CEACAM-1-dependent inhibition of NK cytotoxicity. Previous studies have demonstrated safety/tolerability in non-human primates, and in a first in human phase 1 clinical trial at the National Cancer Institute (NCI). In addition, preclinical studies have demonstrated that NEO-201 can bind to human regulatory T (Treg) cells. The specificity of NEO-201 in recognizing suppressive Treg cells provides the basis for combination cancer immunotherapy with checkpoint inhibitors targeting the PD-1/PD-L1 pathway.

Abstract CT113: A phase II study of prexasertib, a cell cycle checkpoint kinase 1 (CHK1) inhibitor, in platinum-resistant recurrent high-grade serous ovarian cancer (HGSOC) with BRCA wild-type (BRCAwt)

Background: Platinum-resistance is associated with a poor prognosis in HGSOC and has limited treatment options. Inhibition of CHK1 has shown activity in BRCAwt HGSOC. Here, we report the clinical activity and tolerability of the second generation CHK1 inhibitor, prexasertib, in platinum-resistant BRCAwt HGSOC (NCT02203513).

Methods: Eligibility included platinum-resistant recurrent HGSOC women without germline or somatic BRCA mutation, ECOG PS 0-2, good end organ function, and measurable disease. The primary endpoint was response rate (RR). Secondary endpoints were progression-free survival (PFS) and safety. Prexasertib was given at 105 mg/m2 IV every 14 days in a 28-day cycle. CT scans were performed every 2 cycles for RECIST v1.1 evaluation, and safety evaluation using CTCAE v4.0 every cycle. CBC was performed on day 8 of cycle 1 for ANC nadir. Pretreatment clinical samples were collected for biomarker analysis including HR deficiency and circulating tumor cells (CTC).

Results: Between January 2017 and November 2020, 49 patients (median age 64.1 years [IQR 56.8 - 69.9]) received at least one dose. 12 (24.5%) patients were primary platinum-resistant, and 37 (75.5%) were secondary platinum-resistant. All were heavily pretreated (median 4 prior systemic therapies [IQR 3 - 7]), including bevacizumab (79%), PARP inhibitors (44%), and both (2%). 39 patients were evaluable by RECIST and RR was 30.7%. The median PFS was 5.8 months (range 1.7-26.4 months). The median duration of response among PRs was 5.5 months (range 1-19.8 months). The clinical benefit rate (PR+CR+SD >4 months) was 84.6%. 10 patients were inevaluable due to: withdrawal of consent (n=2), intercurrent illness related to disease (tumor invasion of mainstem bronchus (n=1) or vaginal wall (n=1), small bowel obstruction (n=2), infection (n=2), failure to thrive (n=1), and pneumothorax secondary to thoracentesis (n=1) during cycle 1. The common (>10%) grade 3 or 4 adverse events (AEs) included neutropenia (85%, 42/49) based on the cycle 1 day 8 CBC at the time of ANC nadir, lymphocytopenia (46%, 23/49), thrombocytopenia (40%, 20/49), anemia (30%, 15/49), and febrile neutropenia (12%, 5/49). 83% (41/49) of patients received growth factors support to avoid subsequent treatment delays. There were no deaths on the study. No significant difference of RECIST response or PFS was observed in patients with high (≥2) vs low (<2) CTC at baseline.

Conclusions: Prexasertib monotherapy resulted in clinical benefit in subgroups of heavily pretreated BRCAwt platinum-resistant HGSOC. Prexasertib was well tolerated with manageable grade 3/4 AEs. Further studies on predictive biomarkers are ongoing.

Citation Format: Grant Zurcher, Ann McCoy, Brooke Solarz, Jay Nair, Min-Jung Lee, Jane B. Trepel, Christina M. Annunziata, Jung-Min Lee. A phase II study of prexasertib, a cell cycle checkpoint kinase 1 (CHK1) inhibitor, in platinum-resistant recurrent high-grade serous ovarian cancer (HGSOC) with BRCA wild-type (BRCAwt) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT113.

Abstract 3577: First-in-human phase I study of intraperitoneally administered interferon-activated autologous monocytes in platinum-resistant ovarian cancer

Background: Ovarian cancer is the most lethal gynecologic cancer and is intrinsically resistant to immunotherapies. Previous work has demonstrated superior response rates with intraperitoneally (IP) directed therapies, providing the rationale for IP immunotherapy.

Methods: A previously published model system in which OVCAR ovarian cancer spheroids are killed by IFN-activated human monocytes was further characterized using confocal microscopy, global gene expression analysis, flow cytometry, and knockout/knockdown of key genes in the TRAIL-DR4/DR5 pathway. These results were translated into a phase I dose escalation trial in which 3-6 patients with platinum-resistant or refractory ovarian cancer were enrolled into 4 cohorts and treated IP q28 days with Peginterferon alfa-2b (25-250 mcg) and Interferon gamma-1b (5-50 mcg), with or without autologous monocytes (75-750 x 106 cells), in order to determine the recommended phase II dose (RP2D).

Results: Confocal microscopy of IFN-activated monocytes demonstrated migration into OVCAR spheroids and destruction of the spheroids and global gene expression analysis identified TRAIL as a ligand on monocytes upregulated by IFN treatment. Disruption of TRAIL receptors DR4/DR5 or deletion of CASPASE8 on OVCAR cells largely abrogated killing. IFN-activated human monocytes were able to kill IP-injected OVCAR tumor cells in a mouse xenograft model, and IFN-activated monocytes from ovarian cancer patients were able to kill OVCAR spheroids as effectively as those from healthy donors. 18 patients were subsequently enrolled on a phase I trial (median age, 61 years; median 5 prior therapies). 1 of 3 patients at the second dose level experienced a dose-limiting toxicity (grade 3 anemia) and no subsequent DLTs were observed. The RP2D was defined as 250mcg IFNa/50mcg IFNg/750 x 106 cells. The only treatment-related grade 3 or higher adverse events occurring in more than one patient were lymphocyte decrease (33.3%) and abdominal pain (11.1%). The best response observed was partial response (PR) in 2/9 RECIST-evaluable patients, and 1 additional patient had a CA-125 response with >50% reduction. 4/9 patients had stable disease. Four patients were able to receive 5+ cycles (range 1-10 cycles). Biomarker analyses demonstrated that these long-term responders had a lower level of T-regulatory cells at baseline, but exhibited marked increase in myeloid derived suppressor cells (MDSC) at the time of tumor progression.

Conclusion: These findings characterize the mechanism of a novel cellular immunotherapy for ovarian cancer which is well tolerated with evidence of clinical activity in a heavily pretreated patient population. This therapy may serve as the backbone for a combination immunotherapy regimen incorporating additional agents targeting T-regulatory cells and/or MDSCs.

Citation Format: Christopher B. Cole, Daniel S. Green, Franklin Ning, Kathryn Zoon, Lindsey B. Rosen, Steven M. Holland, Christina M. Annunziata. First-in-human phase I study of intraperitoneally administered interferon-activated autologous monocytes in platinum-resistant ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3577.

Abstract 5727: Using ChIP-seq to identify genes regulated by RelA or RelB that support ovarian cancer tumor-initiating cell (TIC) characteristics

Ovarian cancer is the most lethal gynecologic malignancy in the US. Although high-grade serous ovarian cancer (HGSOC) patients initially respond to chemotherapy, over 70% relapse in two years. This paradigm can be understood through ovarian cancer’s pronounced heterogeneity whereby a majority of cancer cells are highly proliferative and chemosensitive and a minority of cells, termed tumor-initiating cells (TICs), are relatively quiescent and chemoresistant stem-like cells. Both are presumed to be important for tumor repopulation. Our lab previously demonstrated that TICs exhibit an upregulation of stem cell genes and NF-κB signaling. RNA sequencing of cells grown in TIC enhancing, non-adherent conditions shows significantly increased expression of NF-kB genes NFKB2, RELA, and RELB, as well as stem cell genes SOX2 and ALDH1A2. In this study, we are investigating the mechanism through which the NF-κB transcription factors RelA and RelB support TICs to promote relapse in ovarian cancer. RNA sequencing of shRNA knockdowns of RELA or RELB from cells grown in TIC conditions shows that RELA knockdown impacts 1415 unique genes, RELB knockdown impacts 2016 unique genes, and RELA or RELB knockdown decreases expression of 1912 shared genes. Gene ontology analysis suggests RELA regulates genes in growth and differentiation pathways while RELB regulates genes in metabolic pathways. Specifically, RELA knockdown significantly decreased expression of NF-kB pathway genes (RELA, RELB, NFKB2) as well as stem cell genes CD117 and ALDH1A2. RELB knockdown significantly decreased expression of NF-kB pathway genes (RELA, RELB) as well as stem cell genes CD117, CD133, ALDH1A1, and ALDH1A2. To expand on these findings we performed ChIP-sequencing of RelA and RelB in OV90 cells cultured in TIC enhancing or adherent monolayer conditions. Our results show that both RelA and RelB bind at promoter sites for NFKBIA and NUAK1 in both conditions. In monolayer cultures RelA uniquely binds 14 different genes, including lncRNAs, miRNAs, and Cyclin L1, important in G0-G1 cell cycle progression. In TIC conditions, RelB uniquely binds 16 different genes, including lncRNAs, miRNAs, and WNT10A, important in stem cell self-renewal. Experiments are underway to validate our top hits in ovarian cancer, using siRNA knockdowns to corroborate the genes and pathways through which RelB supports self-renewal and RelA supports cell cycle progression. The ultimate goal of this project is to identify downstream pathways regulated by NF-kB that can be targeted to overcome relapse in HGSOC.

Citation Format: Emily M. Mu, Samuel F. Gilbert, Mikella Robinson, Jacqueline Lara, Omar Lujano-Olazaba, Christina M. Annunziata, Carrie D. House. Using ChIP-seq to identify genes regulated by RelA or RelB that support ovarian cancer tumor-initiating cell (TIC) characteristics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5727.

Abstract 3188: Modulating UGDH expression in ovarian cancer tumor-initiating cells alters the tumor microenvironment

Epithelial ovarian cancer (EOC) is a global health burden, with the poorest five-year survival rate of the gynecological malignancies due to diagnosis at advanced stage and high recurrence rate. Recurrence in EOC is driven by the survival of chemoresistant, stem-like tumor-initiating cells (TICs) that are supported by a complex extracellular matrix (ECM) and immunosuppressive microenvironment. To target TICs to prevent recurrence, we identified genes critical for TIC viability from a whole genome siRNA screen. A top hit was the cancer-associated, ECM synthesis enzyme UDP-glucose dehydrogenase (UGDH). Immunohistochemistry was used to delineate UGDH expression in histological and molecular subtypes of EOC. Clustering analysis was performed to characterize EOC cell lines to aligned to the molecular subtypes observed in tumors. UGDH expression was modulated in the cell lines using inducible shRNA, and the effects on TICs and on the cells in the supporting microenvironment were examined. High UGDH expression was observed in the majority of high-grade serous ovarian cancers and variable expression was observed in clear cell, mucinous and endometrioid histotypes. A distinctive survival prognostic for UGDH expression was revealed when serous cancers were stratified by molecular subtype, where high UGDH was associated with a poor prognosis in the mesenchymal subtype. Using OV90 as a representative cell line for the mesenchymal subtype, we examined the effect of UGDH knockdown on the tumor cells alone, and on mesothelial support cells in co-culture with the tumor cells. Knock down of UGDH in the OV90 cells reduced the viability, sphere-formation and colony formation capacity of TICs and reduced extracellular hyaluronan production. Knocking down UGDH in the tumors affected the mesothelial cells in co-culture by significantly reducing the expression of ECM signaling and remodeling proteins Versican, Vitronectin, Laminin and matrix metalloprotease 1. These data show that modulation of UGDH expression in tumors influences cells in the microenvironment and reveal a distinct role for UGDH in the mesenchymal molecular subtype of EOC. UGDH is a strong prospective therapeutic target in TICs, for the treatment of metastatic and recurrent EOC, particularly in patients with the mesenchymal molecular subtype.

Citation Format: Brittney S. Harrington, Rahul Kamdar, Nathan Wong, Carrie D. House, Christina M. Annunziata. Modulating UGDH expression in ovarian cancer tumor-initiating cells alters the tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3188.

Abstract 5820: NF-κB signaling regulates miRNA expression in ovarian cancer

Epithelial ovarian cancer (EOC) remains the fifth leading cause of cancer related death in women worldwide, partly due to the survival of chemoresistant, stem-like tumor-initiating cells (TICs) that promote disease relapse. Previous studies described the role of the NF-kB pathway in promoting TIC chemoresistance and survival through the action of key transcription factors (TFs) like RelA and RelB. These TFs serve as key master regulators of genes important for the inflammatory response, which also overlap with the regulation of targets associated with cancer promotion. We previously showed that RelA and RelB exert different effects in ovarian cancer cells, with RelB relatively more important for tumor initiation. In this study, we hypothesize that NF-kB signaling regulates the expression of several microRNAs (miRNAs) differentially through RelA and RelB to promote TIC survival and proliferation. miRNAs comprise a subset of small, noncoding RNAs that regulate gene expression and present potential therapeutic targets for clinical use. Inducible shRNA stably was expressed in OV90 EOC cells to knockdown RelA or RelB; cells were subsequently analyzed by miR-seq to identify differentially expressed miRNAs in cells grown in TIC vs adherent (adh) conditions. To validate the miR-seq findings, we performed qPCR assays of the candidate miRNAs differentially expressed in TIC or adh conditions with RelA or RelB knocked down. We confirmed the decreased expression of oncogenic miRNAs hsa-miR-105-5p and hsa-miR-452-5p, while also confirming the increased expression of tumor suppressive miRNA hsa-miR-34a-5p observed in the miR-seq using OV90 cells. Ongoing work will validate these expression changes in additional cell lines and conduct functional assays to characterize the effect of mimicking or inhibiting these miRNAs of interest. The identification of miRNAs differentially expressed in TICs under the control of RelA or RelB will provide key insights in designing treatments against them to prevent disease relapse in patients with EOC.

Citation Format: Rahul D. Kamdar, Brittney S. Harrington, Soumya Korrapati, Nathan Wong, Carrie D. House, Christina M. Annunziata. NF-κB signaling regulates miRNA expression in ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5820.

Abstract 4185: Targeting variant of CEACAM5 and CEACAM6 using NEO-201 and IL-15 in gynecologic cancers

Background: Uterine and ovarian cancers express glycosylated forms of CEACAMs 5 and 6 that regulate interactions with the tumor microenvironment. NEO-201 is a novel monoclonal antibody that binds a glycosylated variant of these CEACAMs that is upregulated in cancer compared to normal uterine or ovarian epithelia. Previous work has shown that NEO-201 induced cancer cell death predominantly by antibody-dependent cellular cytotoxicity (ADCC) that can be enhanced by the addition of IL-15.

Methods: NEO-201 target expression was assessed on uterine and ovarian cancer cell lines, as well as a tissue microarray of primary uterine cancer samples. Cell lines were profiled with DNA and RNA sequencing. Chromium-release assays were performed to quantify ADCC without and with varying concentrations of IL-15 and varying target to effector ratios. In vivomodeling was performed using ovarian cancer cell line OV90, and mice were treated with NEO-201, with PBMC or NK cells, with or without IL-15.

Results: NEO-201 target antigen was highly expressed in uterine cancer cell line ACI158 and ovarian cancer cell line OV90. The antigen was expressed in primary uterine cancer samples as well. IL-15 consistently increased the in vitro killing of both cell lines and was further enhanced with the use of NK cells compared to PBMC. These findings were replicated in the in vivo mouse model, where mice survived longest with the combination of NEO-201, IL-15 and NK cells.

Conclusions: The ADCC activity of NEO-201 monoclonal antibody was enhanced with the addition of IL-15, especially in the presence of purified NK cells. NEO-201 with IL-15 shows promising results as a potential treatment for biomarker-selected gynecologic cancers.

Citation Format: Maria Pia Morelli, Massimo Fantini, Kwong Y. Tsang, Phillip Arlen, Paulette Fauceglia, Lidia Hernandez, Soumya Korrapati, Elijah Edmonson, Christopher Cole, Christina M. Annunziata. Targeting variant of CEACAM5 and CEACAM6 using NEO-201 and IL-15 in gynecologic cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4185.

Another Wrinkle with Age: Aged Collagen and Intra-peritoneal Metastasis of Ovarian Cancer

Background

Age is the most significant risk factor for ovarian cancer (OvCa), the deadliest gynecologic malignancy. Metastasizing OvCa cells adhere to the omentum, a peritoneal structure rich in collagen, adipocytes, and immune cells. Ultrastructural changes in the omentum and the omental collagen matrix with aging have not been evaluated.

Aim

The aim of this study was to test the hypothesis that age-related changes in collagen in the ovarian tumor microenvironment promote OvCa metastatic success in the aged host.

Methods/Results

Young (3-6 months) and aged mice (20-23 months) were used to study the role of aging in metastatic success. Intra-peritoneal (IP) injection of ID8Trp53 ^-/- ovarian cancer cells showed enhanced IP dissemination in aged vs young mice. In vitro assays using purified collagen demonstrated reduced collagenolysis of aged fibers, as visualized using scanning electron microscopy (SEM) and quantified with a hydroxyproline release assay. Omental tumors in young and aged mice showed similar collagen deposition; however enhanced intra-tumoral collagen remodeling was seen in aged mice probed with a biotinylated collagen hybridizing peptide (CHP). In contrast, second harmonic generation (SHG) microscopy showed significant differences in collagen fiber structure and organization in omental tissue and SEM demonstrated enhanced omental fenestration in aged omenta. Combined SHG and Alexa Fluor-CHP microscopy in vivo demonstrated that peri-tumoral collagen was remodeled more extensively in young mice. This collagen population represents truly aged host collagen, in contrast to intra-tumoral collagen that is newly synthesized, likely by cancer associated fibroblasts (CAFs).

Conclusions

Our results demonstrate that tumors in an aged host can grow with minimal collagen remodeling, while tumors in the young host must remodel peri-tumoral collagen to enable effective proliferation, providing a mechanism whereby age-induced ultrastructural changes in collagen and collagen-rich omenta establish a permissive pre-metastatic niche contributing to enhanced OvCa metastatic success in the aged host.

Phase I clinical trial of NEO-201, an anti-tumor-associated CEACAM-5/6 monoclonal antibody in solid tumors

2531

Background: NEO201 is a humanized IgG1 monoclonal antibody generated against tumor-associated antigens from colorectal cancer which binds specifically to tumor-associated CEACAM-5 and CEACAM-6 variants without binding CECAM 5/6 on normal epithelial tissues. NEO-201 reactivity is positive in the majority of adenocarcinomas including colon (85%), pancreas (86%), lung (79%), and breast (53%). Preclinical data showed that NEO-201 exerts anti-tumor activity through antibody dependent cellular cytotoxicity and complement dependent cytotoxicity. Here we present outcomes from a phase I trial of NEO-201 in advanced solid tumors (NCT03476681). Methods: This was a classic 3+3 dose escalation trial, with cohort expansion at the RP2D. NEO-201 was administered intravenously every two weeks in a 28-day cycle. The primary objective was to assess the MTD/RP2D of NEO-201 in patients with advanced solid tumors. The secondary objective was to assess the preliminary antitumor activity and exploratory objectives assessed pharmacokinetics and the effect of NEO-201 administration on immunologic parameters and possible relationships with response. Of 17 patients enrolled, 11 had colorectal, 4 had pancreatic and 2 had breast cancer. 4 patients received NEO-201 at dose level (DL) 1 (1 mg/kg), 6 patients at DL 1.5 (1.5 mg/kg) and 7 patients at dose DL 2 (2 mg/kg). Results: At the time of data cutoff, all patients had discontinued therapy. 11 of 14 evaluable patients discontinued due to disease progression and 3 patients discontinued due to DLT (grade 4 febrile neutropenia and prolonged neutropenia, each in 1/6 patients at DL2, and grade 3 febrile neutropenia in 1/6 patients at DL 1.5). Most common grade 3/4 toxicities were neutropenia (94%), white blood cell decrease (59%), lymphocyte decrease (29%), and febrile neutropenia (24%). Protocol was modified to allow administration of G-CSF and based on safety and PK data the RP2D was established as 1.5mg/Kg. Median number of doses received was 4.7. 13 subjects were able to undergo disease assessment after two cycles. The best response observed was stable disease (SD) in 5/9 evaluable patients with colorectal cancer. Minor CA-19-9 reductions were observed in two pancreatic cancer patients at DL 1.5. Correlative endpoints revealed that all patients enrolled in the trial expressed NEO-201 target antigen on their tumor tissue. Analysis of soluble factors in serum revealed that a high level of soluble MICA at baseline was correlated with a downregulation of NK cell activation markers and progressive disease. Unexpectedly, flow cytometry showed that NEO-201 also binds to circulating T regulatory cells and depleted these cells especially in patients with SD. Conclusions: NEO-201 was safe and well tolerated at the MTD of 1.5 mg/kg. Depletion of T regulatory cells suggests that the combination of NEO-201 with immune checkpoint inhibitor should be tested in future clinical trials. Clinical trial information: NCT03476681.

Disulfiram Transcends ALDH Inhibitory Activity When Targeting Ovarian Cancer Tumor-Initiating Cells

Epithelial ovarian cancer (EOC) is a global health burden and remains the fifth leading cause of cancer related death in women worldwide with the poorest five-year survival rate of the gynecological malignancies. EOC recurrence is considered to be driven by the survival of chemoresistant, stem-like tumor-initiating cells (TICs). We previously showed that disulfiram, an ALDH inhibitor, effectively targeted TICs compared to adherent EOC cells in terms of viability, spheroid formation, oxidative stress and also prevented relapse in an in vivo model of EOC. In this study we sought to determine whether specific targeting of ALDH isoenzyme ALDH1A1 would provide similar benefit to broader pathway inhibition by disulfiram. NCT-505 and NCT-506 are isoenzyme-specific ALDH1A1 inhibitors whose activity was compared to the effects of disulfiram. Following treatment with both the NCTs and disulfiram, the viability of TICs versus adherent cells, sphere formation, and cell death in our in vitro relapse model were measured and compared in EOC cell lines. We found that disulfiram decreased the viability of TICs significantly more effectively versus adherent cells, while no consistent trend was observed when the cells were treated with the NCTs. Disulfiram also affected the expression of proteins associated with NFκB signaling. Comparison of disulfiram to the direct targeting of ALDH1A1 with the NCTs suggests that the broader cellular effects of disulfiram are more suitable as a therapeutic to eradicate TICs from tumors and prevent EOC relapse. In addition to providing insight into a fitting treatment for TICs, the comparison of disulfiram to NCT-505 and -506 has increased our understanding of the mechanism of action of disulfiram. Further elucidation of the mechanism of disulfiram has the potential to reveal additional targets to treat EOC TICs and prevent disease recurrence.

Abstract P127: Mitochondrial matrix protease ClpP agonists suppress breast cancer stem cell function by downregulating multiple stem cell regulatory mechanisms

Background: We previously reported that small molecule ONC201 induces mitochondrial structural and functional damage, leading to death in breast cancer cells. Subsequent studies demonstrated that ONC201 and the related analogs TR compounds are agonists of mitochondrial caseinolytic protease P (ClpP), an essential protein for maintenance of mitochondrial protein homeostasis. Recent studies have shown that cancer stem cells (CSCs) preferentially use mitochondrial oxidative metabolism for energy production. Here, we report that ClpP agonists inhibit breast CSCs by unique mechanisms targeting pathways vital to maintain CSC function. Methods: ONC201 and other ClpP agonists (TR-57, 65), other mitochondria-targeting drugs, such as oligomycin, metformin, CPI-613 were used. MDA-MB231 cell line was used as a primary in vitro model system. CLPP knockout (KO) cells were generated by CRISPR/Cas9 technology. Seahorse XF analyzer was used for cellular respiration analysis. Luminescence-based assays were used for cell viability and metabolism assays. Protein expression was examined by Western blotting. Aldefluor assay and SORE6 (OCT4/SOX2 response element)-reporter gene were used to monitor CSC fraction. Mammosphere formation assay was used to evaluate CSC function in vitro. In vivo limiting dilution analysis was used to evaluate tumor initiation capability of cells injected into mammary fat pad of athymic nude female mice. Results: Seahorse XF analyzer showed that mammospheres are more dependent on OxPhos than glycolysis compared with cells grown in 2D, supporting the hypothesis that breast CSCs rely on OxPhos. ClpP agonists reduced the CSC fraction in both Aldefluor and SORE6 reporter assays. ClpP agonists inhibited mammosphere formation in CLPP WT, but not in CLPP KO cells, demonstrating the on-target effects on CSC function. In in vivo assays, tumor formation was significantly (p<0.001) inhibited in the ClpP agonist-treated group compared with the control group, and the effect was CLPP-dependent. Altogether, these findings support that ClpP agonists inhibit CSC in breast cancers. We found that ClpP agonists downregulate multiple pathways and proteins critical for CSC maintenance including mevalonate pathway, HIF1a, EPAS1, YAP, and Myc. We also observed that other mitochondria targeting drugs such as oligomycin, metformin downregulate these signaling pathways and proteins to some extent. Importantly, however, ClpP agonists showed significantly greater impact in mammosphere formation and cell growth assays, compared with other mitochondria-targeting drugs. Further studies revealed that ClpP agonists uniquely deplete NAD+/NADH and promote reactive oxygen species, both of which are shown as key factors to maintain pluripotency of stem cells. Moreover, ClpP agonists uniquely inhibited enzymes involved with glutamine catabolism and proline biosynthesis, vital to amino acids and nucleotide synthesis. Conclusion: ClpP agonists inhibit cell growth and tumor initiation in breast cancer cells by targeting multiple pathways essential to maintain CSC function.

Citation Format: Yoshimi E. Greer, Lidia Hernandez, Donna Voeller, Raj Chari, Binwu Tang, Christina M. Annunziata, Sam Gilbert, Lalage Wakefield, Edwin Iwanowicz, Lee M. Graves, Stanley Lipkowitz. Mitochondrial matrix protease ClpP agonists suppress breast cancer stem cell function by downregulating multiple stem cell regulatory mechanisms [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 P127.

Pilot Study Assessing Tolerability and Metabolic Effects of Metformin in Patients With Li-Fraumeni Syndrome

Background

Li-Fraumeni syndrome (LFS) is a highly penetrant autosomal dominant cancer predisposition disorder caused by germline TP53 pathogenic variants. Patients with LFS have increased oxidative phosphorylation capacity in skeletal muscle and oxidative stress in blood. Metformin inhibits oxidative phosphorylation, reducing available energy for cancer cell proliferation and decreasing production of reactive oxygen species that cause DNA damage. Thus, metformin may provide pharmacologic risk reduction for cancer in patients with LFS, but its safety in nondiabetic patients with germline TP53 pathogenic variants has not been documented.

Methods

This study assessed safety and tolerability of metformin in nondiabetic LFS patients and measured changes in metabolic profiles. Adult patients with LFS and germline TP53 variant received 14 weeks of metformin. Blood samples were obtained for measurement of serum insulin-like growth factor-1, insulin, and insulin-like growth factor binding protein 3. Hepatic mitochondrial function was assessed with fasting exhaled CO₂ after ingestion of ¹³C-labeled methionine. Changes in serum metabolome were measured. All statistical tests were 2-sided.

Results

We enrolled 26 participants: 20 females and 6 males. The most common adverse events were diarrhea (50.0%) and nausea (46.2%). Lactic acidosis did not occur, and there were no changes in fasting glucose. Cumulative mean ¹³C exhalation was statistically significantly suppressed by metformin (P = .001). Mean levels of insulin-like growth factor binding protein 3 and insulin-like growth factor-1 were statistically significantly lowered (P = .02). Lipid metabolites and branched-chain amino acids accumulated.

Conclusions

Metformin was safe and tolerable in patients with LFS. It suppressed hepatic mitochondrial function as expected in these individuals. This study adds to the rationale for development of a pharmacologic risk-reduction clinical trial of metformin in LFS.

Driving Immune Responses in the Ovarian Tumor Microenvironment

Ovarian cancer is the leading cause of death among gynecological neoplasms, with an estimated 14,000 deaths in 2019. First-line treatment options center around a taxane and platinum-based chemotherapy regimen. However, many patients often have recurrence due to late stage diagnoses and acquired chemo-resistance. Recent approvals for bevacizumab and poly (ADP-ribose) polymerase inhibitors have improved treatment options but effective treatments are still limited in the recurrent setting. Immunotherapy has seen significant success in hematological and solid malignancies. However, effectiveness has been limited in ovarian cancer. This may be due to a highly immunosuppressive tumor microenvironment and a lack of tumor-specific antigens. Certain immune cell subsets, such as regulatory T cells and tumor-associated macrophages, have been implicated in ovarian cancer. Consequently, therapies augmenting the immune response, such as immune checkpoint inhibitors and dendritic cell vaccines, may be unable to properly enact their effector functions. A better understanding of the various interactions among immune cell subsets in the peritoneal microenvironment is necessary to develop efficacious therapies. This review will discuss various cell subsets in the ovarian tumor microenvironment, current immunotherapy modalities to target or augment these immune subsets, and treatment challenges.

Rapid image deconvolution and multiview fusion for optical microscopy

The contrast and resolution of images obtained with optical microscopes can be improved by deconvolution and computational fusion of multiple views of the same sample, but these methods are computationally expensive for large datasets. Here we describe theoretical and practical advances in algorithm and software design that result in image processing times that are tenfold to several thousand fold faster than with previous methods. First, we show that an 'unmatched back projector' accelerates deconvolution relative to the classic Richardson-Lucy algorithm by at least tenfold. Second, three-dimensional image-based registration with a graphics processing unit enhances processing speed 10- to 100-fold over CPU processing. Third, deep learning can provide further acceleration, particularly for deconvolution with spatially varying point spread functions. We illustrate our methods from the subcellular to millimeter spatial scale on diverse samples, including single cells, embryos and cleared tissue. Finally, we show performance enhancement on recently developed microscopes that have improved spatial resolution, including dual-view cleared-tissue light-sheet microscopes and reflective lattice light-sheet microscopes.

Leveraging locus-specific epigenetic heterogeneity to improve the performance of blood-based DNA methylation biomarkers

BACKGROUND

Variation in intercellular methylation patterns can complicate the use of methylation biomarkers for clinical diagnostic applications such as blood-based cancer testing. Here, we describe development and validation of a methylation density binary classification method called EpiClass (available for download at https://github.com/Elnitskilab/EpiClass ) that can be used to predict and optimize the performance of methylation biomarkers, particularly in challenging, heterogeneous samples such as liquid biopsies. This approach is based upon leveraging statistical differences in single-molecule sample methylation density distributions to identify ideal thresholds for sample classification.

RESULTS

We developed and tested the classifier using reduced representation bisulfite sequencing (RRBS) data derived from ovarian carcinoma tissue DNA and controls. We used these data to perform in silico simulations using methylation density profiles from individual epiallelic copies of ZNF154, a genomic locus known to be recurrently methylated in numerous cancer types. From these profiles, we predicted the performance of the classifier in liquid biopsies for the detection of epithelial ovarian carcinomas (EOC). In silico analysis indicated that EpiClass could be leveraged to better identify cancer-positive liquid biopsy samples by implementing precise thresholds with respect to methylation density profiles derived from circulating cell-free DNA (cfDNA) analysis. These predictions were confirmed experimentally using DREAMing to perform digital methylation density analysis on a cohort of low volume (1-ml) plasma samples obtained from 26 EOC-positive and 41 cancer-free women. EpiClass performance was then validated in an independent cohort of 24 plasma specimens, derived from a longitudinal study of 8 EOC-positive women, and 12 plasma specimens derived from 12 healthy women, respectively, attaining a sensitivity/specificity of 91.7%/100.0%. Direct comparison of CA-125 measurements with EpiClass demonstrated that EpiClass was able to better identify EOC-positive women than standard CA-125 assessment. Finally, we used independent whole genome bisulfite sequencing (WGBS) datasets to demonstrate that EpiClass can also identify other cancer types as well or better than alternative methylation-based classifiers.

CONCLUSIONS

Our results indicate that assessment of intramolecular methylation density distributions calculated from cfDNA facilitates the use of methylation biomarkers for diagnostic applications. Furthermore, we demonstrated that EpiClass analysis of ZNF154 methylation was able to outperform CA-125 in the detection of etiologically diverse ovarian carcinomas, indicating broad utility of ZNF154 for use as a biomarker of ovarian cancer.

Abstract 3582: Drugs targeting ovarian cancer tumor-initiating cells enhance oxidative stress and prevent disease recurrence

Ovarian cancer (OC) is a global health burden with the poorest 5-year survival rate of the gynecological malignancies. Disease recurrence is the major cause of morbidity and mortality of OC, likely driven by the survival of chemoresistant, self-renewing tumor-initiating cells (TICs). The TIC population in OC acquires features to survive cellular stress and avoid apoptosis but these can also be targeted as vulnerabilities specific to the TIC population of OC to prevent recurrence. To reveal these vulnerabilities, a high-throughput drug screen was performed to identify drugs that showed increased efficacy against OC cells grown in TIC-enriching spheroid (TES) conditions compared to adherently grown cells. Four drugs were selected for further investigation. Disulfiram, Bardoxolone Methyl, Elesclomol and Salinomycin were tested in vitro to confirm the effects on viability of OC cells in adherent or TES conditions. The drugs' efficacy against sphere formation and expression of markers of stemness as high ALDH activity and CD133 expression (ALDH+CD133+) as single agents or in combination with carboplatin was also investigated in vitro. Disulfiram showed the greatest efficacy against spheroid viability and decreased the ALDH+CD133+ population of several OC cell lines. This effect was enhanced when combined with carboplatin. Bardoxolone Methyl, Elesclomol and Salinomycin showed similar efficacy against cell viability in OC cells grown adherently or in TES conditions; Elesclomol significantly inhibited the ALDH+CD133+ population of the OC cells which was again enhanced in combination with carboplatin. RNAseq analysis revealed a strong enrichment of genes involved in oxidative phosphorylation and reactive oxygen species (ROS) pathways in TES conditions compared to adherent conditions. The drugs were investigated for their ability to promote oxidative stress and OC cells were measured for accumulation of intracellular ROS and mitochondrial superoxide after exposure to the drugs. OC cells grown in TES conditions had higher basal intracellular ROS levels than adherently grown cells and the level of ROS was significantly enhanced in TES cells treated with Elesclomol or Disulfiram but no differences were seen in adherently grown cells. Salinomycin and Bardoxolone Methyl increased mitochondrial superoxide accumulation in some OC cell lines under TES conditions. In a model of OC relapse in vitro, Disulfiram and Elesclomol following carboplatin treatment significantly increased cell death compared to carboplatin alone. Disulfiram and Salinomycin were incorporated into a mouse model to test their ability to prevent OC relapse after chemotherapy in vivo. These results demonstrate that targeting key pathways mediating increased oxidative stress in TICs can eliminate this population and provide a means to prevent OC recurrence.

Citation Format: Brittney S. Harrington, Christina M. Annunziata. Drugs targeting ovarian cancer tumor-initiating cells enhance oxidative stress and prevent disease recurrence [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 3582.

Combination of PARP Inhibitor Olaparib, and PD-L1 Inhibitor Durvalumab, in Recurrent Ovarian Cancer: a Proof-of-Concept Phase II Study

PURPOSE

Preclinical studies suggest PARP inhibition (PARPi) induces immunostimulatory micromilieu in ovarian cancer thus complementing activity of immune checkpoint blockade. We conducted a phase II trial of PARPi olaparib and anti-PD-L1 durvalumab and collected paired fresh core biopsies and blood samples to test this hypothesis.

PATIENTS AND METHODS

In a single-center, proof-of-concept phase II study, we enrolled women aged ≥18 with recurrent ovarian cancer. All patients were immune checkpoint inhibitor-naïve and had measurable disease per RECISTv1.1, ECOG performance status 0-2, and adequate organ and marrow function. Patients received olaparib 300 mg twice daily and durvalumab 1,500 mg intravenously every 4 weeks until disease progression, unacceptable toxicity, or withdrawal of consent. Primary endpoint was overall response rate (ORR). Secondary objectives were safety and progression-free survival (PFS). Translational objectives included biomarker evaluation for relationships with clinical response and immunomodulatory effects by treatment.

RESULTS

Thirty-five patients with ovarian cancer [median, four prior therapies (IQR, 2-5.5), predominantly platinum-resistant (86%), BRCA wild-type (77%)] received at least one full cycle of treatment. ORR was 14% [5/35; 95% confidence interval (CI), 4.8%-30.3%]. Disease control rate (PR+SD) was 71% (25/35; 95% CI, 53.7%-85.4%). Treatment enhanced IFNγ and CXCL9/CXCL10 expression, systemic IFNγ/TNFα production, and tumor-infiltrating lymphocytes, indicating an immunostimulatory environment. Increased IFNγ production was associated with improved PFS [HR, 0.37 (95% CI, 0.16-0.87), P = 0.023], while elevated VEGFR3 levels were associated with worse PFS (HR, 3.22 (95% CI, 1.23-8.40), P = 0.017].

CONCLUSIONS

The PARPi and anti-PD-L1 combination showed modest clinical activity in recurrent ovarian cancer. Our correlative study results suggest immunomodulatory effects by olaparib/durvalumab in patients and indicate that VEGF/VEGFR pathway blockade would be necessary for improved efficacy of the combination.

Abstract 4534: A therapeutic humanized anti-carcinoma monoclonal antibody (mAb) can enhance NK activity and target immunosuppressive regulatory T cells

Background: NEO-201 is a therapeutic IgG1 humanized mAb reactive against many different carcinomas, but not reactive against most normal tissues. No reactivity was observed with NEO-201 in subsets of hematopoietic cells except CD15+ granulocytes. Functional analysis revealed that NEO-201 is capable of engaging in ADCC and CDC to kill tumor cells. Previous studies showed that NEO-201 attenuates growth of human tumor xenografts in mice and demonstrates safety/tolerability in non-human primates with a transient decrease in neutrophils being the only adverse effect observed. A first in human clinical trial evaluating NEO-201 in adults with chemo-resistant solid tumors is ongoing at the NIH clinical Center. NEO-201 recognizes tumor-associated variants of CEACAM5 and 6. CEACAM1 is a potent inhibitor of natural killer (NK) cell function; binding between CEACAM1 on NK cells and CEACAM1 or CEACAM5 on tumor cells inhibits activation signaling by NKG2D, which prevents NK cell cytolysis and permits tumor cells to evade NK killing. Preclinical evaluation showed that NEO-201 reacts against human regulatory T cells (Tregs). This study was designed to assess NK enhancing pathway and further investigated the phenotypic and functional effects of NEO-201 on human Tregs in vitro.

Materials & Methods: Various human tumor cell lines were used as target cells and NK-92 cells (CEACAM1+/CD16-) were used as effectors to assess the ability of NEO-201 to block the interaction between CEACAM5 on tumor cells and CEACAM1 on NK cells in order to enhance the in vitro killing of tumor cells. Phenotypic analysis was conducted by flow cytometry for Treg markers: CD4, CD25, CD127, FoxP3, CD15s, CD45RA, CCR4, NEO-201 antigen, CEACAM5 and CEACAM6.

Results: Functional analysis revealed that NEO-201 is capable of engaging enhancing NK-92 activity to kill tumor cells. Expression profiling revealed that various tumor cell lines expressed different levels of CEACAM5+ and NEO-201+ cells. Addition of NEO-201 significantly enhanced NK-92 cell cytotoxicity against highly CEACAM5+/NEO-201+ cells, suggesting that its activity is correlated with the level of CEACAM5+/NEO-201+ tumor cells. Furthermore, the % of NEO-201+ cells in the population of CD4+CD25highCD127negFoxP3+CD15s+CCR4+Tregs ranged from 60%-80%. NEO-201 mAb mediated CDC activity against Tregs.

Conclusions: This study demonstrates NEO-201 can block the interaction between tumor cell CEACAM5 and NK cell CEACAM1 to reverse CEACAM1-dependent inhibition of NK killing. NEO-201 can also target and eliminate human immunosuppressive regulatory T cells (Tregs).

Citation Format: Massimo Fantini, Maria Pia Morelli, Christina M. Annunziata, Philip M. Arlen, Kwong Y. Tsang. A therapeutic humanized anti-carcinoma monoclonal antibody (mAb) can enhance NK activity and target immunosuppressive regulatory T cells [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 4534.

Phase II trial of bevacizumab and sorafenib in recurrent ovarian cancer patients with or without prior-bevacizumab treatment

OBJECTIVE

To examine whether blocking multiple points of the angiogenesis pathway by addition of sorafenib, a multi-kinase inhibitor against VEGFR2/3, Raf, c-Kit, and PDGFR, to bevacizumab would yield clinical activity in ovarian cancer (OvCa).

METHODS

This phase II study tested bevacizumab plus sorafenib in two cohorts; bevacizumab-naïve and bevacizumab-exposed patients. Bevacizumab (5 mg/kg IV every 2 weeks) was given with sorafenib 200 mg bid 5 days-on/2 days-off. The primary objective was response rate using a Simon two-stage optimal design. Progression-free survival (PFS) and toxicity were the secondary endpoints. Exploratory correlative studies included plasma cytokine concentrations, tissue proteomics and dynamic contrast-enhanced-magnetic resonance imaging (DCE-MRI).

RESULTS

Between March 2007 and August 2012, 54 women were enrolled, 41 bevacizumab-naive and 13 bevacizumab-prior, with median 5 (2-9) and 6 (5-9) prior systemic therapies, respectively. Nine of 35 (26%) evaluable bevacizumab-naive patients attained partial responses (PR), and 18 had stable disease (SD) ≥ 4 months. No responses were seen in the bevacizumab-prior group and 7 (54%) patients had SD ≥ 4 months, including one exceptional responder with SD of 27 months. The overall median PFS was 5.5 months (95%CI: 4.0-6.8 months). Treatment-related grade 3/4 adverse events (≥5%) included hypertension (17/54 [31%]; grade 3 in 16 patients and grade 4 in one patient) and venous thrombosis or pulmonary embolism (5/54 [9%]; grade 3 in 4 patients and grade 4 in one patient). Pretreatment low IL8 concentration was associated with PFS ≥ 4 months (p = .031).

CONCLUSIONS

The bevacizumab and sorafenib combination did not meet the pre-specified primary endpoint although some clinical activity was seen in heavily-pretreated bevacizumab-naive OvCa patients with platinum-resistant disease. Anticipated class toxicities required close monitoring and dose modifications.

Drugs Targeting Tumor-Initiating Cells Prolong Survival in a Post-Surgery, Post-Chemotherapy Ovarian Cancer Relapse Model

Disease recurrence is the major cause of morbidity and mortality of ovarian cancer (OC). In terms of maintenance therapies after platinum-based chemotherapy, PARP inhibitors significantly improve the overall survival of patients with BRCA mutations but is of little benefit to patients without homologous recombination deficiency (HRD). The stem-like tumor-initiating cell (TIC) population within OC tumors are thought to contribute to disease recurrence and chemoresistance. Therefore, there is a need to identify drugs that target TICs to prevent relapse in OC without HRD. RNA sequencing analysis of OC cells grown in TIC conditions revealed a strong enrichment of genes involved in drug metabolism, oxidative phosphorylation and reactive oxygen species (ROS) pathways. Concurrently, a high-throughput drug screen identified drugs that showed efficacy against OC cells grown as TICs compared to adherent cells. Four drugs were chosen that affected drug metabolism and ROS response: disulfiram, bardoxolone methyl, elesclomol and salinomycin. The drugs were tested in vitro for effects on viability, sphere formation and markers of stemness CD133 and ALDH in TICs compared to adherent cells. The compounds promoted ROS accumulation and oxidative stress and disulfiram, elesclomol and salinomycin increased cell death following carboplatin treatment compared to carboplatin alone. Disulfiram and salinomycin were effective in a post-surgery, post-chemotherapy OC relapse model in vivo, demonstrating that enhancing oxidative stress in TICs can prevent OC recurrence.

Evaluation of the Anti-Tumor Activity of the Humanized Monoclonal Antibody NEO-201 in Preclinical Models of Ovarian Cancer

Purpose: Despite high initial response rates with cytoreductive surgery, conventional chemotherapy and the incorporation of biologic agents, ovarian cancer patients often relapse and die from their disease. New approaches are needed to improve patient outcomes. This study was designed to evaluate the antitumor activity of NEO-201 monoclonal antibody (mAb) in preclinical models of ovarian cancer where the NEO-201 target is highly expressed.

Experimental Design: Functional analysis of NEO-201 against tumor cell lines was performed by antibody-dependent cellular cytotoxicity (ADCC) assays. Binding of NEO-201 to tumor tissues and cell lines were determined by immunohistochemistry (IHC) and flow cytometry, respectively. Further characterization of the antigen recognized by NEO-201 was performed by mass spectrometry. Ovarian cancer models were used to evaluate the anti-tumor activity of NEO-201 in vivo. NEO-201 at a concentration of 250 g/mouse was injected intraperitoneally (IP) on days 1, 4, and 8. Human PBMCs were injected IP simultaneously as effector cells.

Results: Both IHC and flow cytometry revealed that NEO-201 binds prominently to the colon, pancreatic, and mucinous ovarian cancer tissues and cell lines. Immunoprecipitation of the antigen recognized by NEO-201 was performed in human ovarian, colon, and pancreatic cancer cell lines. From these screening, carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) and CEACAM6 were identified as the most likely targets of NEO-201. Our results confirmed that NEO-201 binds different types of cancers; the binding is highly selective for the tumor cells without cross reactivity with the surrounding healthy tissue. Functional analysis revealed that NEO-201 mediates ADCC killing against human ovarian and colorectal carcinoma cell lines in vitro. In addition, NEO-201 inhibited tumor growth in the presence of activated human PBMCs in orthotopic mouse models of both primary and metastatic ovarian cancer. Importantly, NEO-201 prolonged survival of tumor-bearing mice.

Conclusions: These data suggested that NEO-201 has an antitumor activity against tumor cells expressing its antigen. Targeting an antigen expressed in tumors, but not in normal tissues, allows patient selection for optimal treatment. These findings strongly indicate that NEO-201 warrants clinical testing as both a novel therapeutic and diagnostic agent for treatment of ovarian carcinomas. A first in human clinical trial evaluating NEO-201 in adults with chemo-resistant solid tumors is ongoing at the NIH clinical Center.

Feasibility and preliminary safety and efficacy of first-in-human intraperitoneal delivery of MCY-M11, anti-human-mesothelin CAR mRNA transfected into peripheral blood mononuclear cells, for ovarian cancer and malignant peritoneal mesothelioma

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Background: MCY-M11 is a mesothelin-targeting chimeric antigen receptor (CAR) therapy made by a non-viral, mRNA-based platform, for rapid ( < 1 day) CAR manufacturing. We are conducting a phase I dose escalation trial in ovarian cancer and malignant peritoneal mesothelioma (MPM) (NCT03608618). Methods: MCY-M11 are fresh, non-expanded, autologous peripheral blood mononuclear cells (PBMCs) transfected by flow electroporation with mRNA encoding a human anti-mesothelin CAR. Following a 3+3 design, patients are treated in dose level (DL) escalating cohorts (DL1 1.0 x 107, DL2 5.0 x 107, DL3 1.0 x 108, DL4 5.0 x 108 cells/dose), in one cycle of weekly x 3 doses, intraperitoneal (ip) without preconditioning chemotherapy. Results: By January 2020, CP-M11-101 study successfully completed DL1 and DL2 without safety concerns. Based on 11 patients treated in DL1, DL2 and DL3, ip infusion of MCY-M11 is safe and well tolerated. No infusion-related adverse events and no dose limiting toxicities (DLTs) have occurred. No neurotoxicity has been observed. Most reported treatment-related adverse events have been Grades 1-2 per NCI CTCAE. One patient in DL3 presented with G2 pericarditis, fever and transient neutropenia clinically assessed as related SAEs, that resolved without further complications. These events were assessed as on-target off-tumor effects and possibly G1 cytokine release syndrome (CRS). Two unrelated SAEs (G2 confusion in a patient in DL2; G3 enterocutaneous fistula in a patient in DL3) were reported. These 2 patients have been replaced as they did not complete the evaluation period (3 weekly infusions and the DLT 43 day follow up). There have been no treatment-related discontinuations or deaths. Three patients in DL2 showed stable disease (SD) by RECIST 1.1 at the end of the DLT period. Of them, 1 completed the study and did not participate in additional follow up, 1 remained in SD 6 months, and 1 remained in SD 2 months. In DL3, 1 patient remains in SD at 2 months, and evaluation is pending for the other 2 patients. Enrollment is ongoing. Conclusions: Feasibility of 1-day manufacturing of MCY-M11 for ip delivery is demonstrated. Treatment has been safe. Initial SD observed in DL2 and DL3 with one-cycle infusions is encouraging and supports exploration of additional strategies such as the addition of preconditioning chemotherapy and multiple cycles to increase efficacy. Clinical trial information: NCT03608618 .

Correlation of clinical activity of NEO201 mAb with the expression of NK activation markers and levels of soluble factors

e15002

Background: NEO-201 is a humanized IgG1 mAb that targets tumor-associated variants of CEACAM-5/6. NEO201 exerts anti-tumor activity by (NK)-mediated ADCC, CDC, and by enhancing NK cell cytotoxicity through blockade of CEACAM5-CEACAM1 interaction. The first in human phase I clinical trial is ongoing. Neutropenia caused DLT and was observed at 2mg/kg (DL 2). At DL2, 2/6 patients with colorectal cancers had stable disease. In the present study we evaluated the correlation between response, NK status, and profiles of soluble factors. Methods: This is a classic 3+3 dose escalation. NEO-201 is administered intravenously every 2 weeks, with 4 dose levels planned (DL1 = 1mg/kg, DL2 = 2mg/kg, DL3 = 4mg/kg and DL4 = 6mg/kg). So far, 3 patients received DL1 and 6 patients DL2. Safety is evaluated according to CTCAEv5.0, and response according to RECISTv1.1. Biological samples are collected at baseline, at 4, 24 and 72 hours after the first dose, and before C1D15 dose to understand NEO-201 pharmacokinetics (PK), effects on immune profile and correlation with treatment toxicity and response. CD56+/CD16+ NK cells were evaluated for modulation of NKG2D, CD107a, NKp46 (activation markers), and CEACAM1 (inhibitory marker) by flow cytometry. Soluble factors (cytokines, sMICA and sCEACAM5) were evaluated by ELISA. Results: Among the 3 patients achieving radiological SD, one (DL1) had clinical progression (PD) without radiological progression after 2 cycles due to mucous producing disease, a second patient (DL2) went off study after 2 cycles for drug unrelated issues, and the third patient (DL2) has stable disease (SD) for 6 months without significant toxicity. All other patients had radiologic PD after 2 cycles. Interestingly, baseline CD56+/CD16+ NK cells from the two patients with SD showed an increase in NKG2D, CD107a and NKp46, and a low expression of CEACAM1. They also had low serum levels of sMICA, sCEACAM5 and IL-6. On contrary, CD56+/CD16+ NK cells from patients with PD had low expression of NKG2D and CD107a, high expression of CEACAM1, and high levels of sMICA. Conclusions: High expression of activating markers and low expression of CEACAM1 on CD56+/CD16+ NK cells, as well as low levels of sMICA and sCEACAM5 correlate with clinical response to NEO-201. Thus, the activity of NK cells may serve as predictors for efficacy of tumor-targeting antibody therapy. Further correlation of these biomarkers with PK and CEACAM1/5/6 expression in patients’ tissue samples will provide further support for optimizing the use of NEO201. Clinical trial information: NCT03476681 .

Prexasertib, a cell cycle checkpoint kinase 1 inhibitor, in BRCA mutant recurrent high-grade serous ovarian cancer (HGSOC): A proof-of-concept single arm phase II study

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Background: Preclinical data suggest cell cycle checkpoint inhibition induces greater cell death in BRCA mutant HGSOC by causing replication stress and dysregulation of DNA damage responses. We hypothesized that prexasertib, a cell cycle checkpoint kinase 1 (CHK1) inhibitor, would be active in BRCA mutated HGSOC patients. Methods: We conducted a single center, two-stage phase II study of prexasertib (105mg/m2 IV every 2 weeks) in HGSOC patients with known germline or somatic BRCA mutations. The primary endpoint was RECIST response rate (RR). Progression-free survival (PFS) and safety (CTCAE v4) were secondary endpoints. Baseline research biopsies and blood samples were collected for exploratory biomarker endpoints. Results: Between February 2015 and July 2019, 22 heavily pretreated (median 5 prior systemic therapies [1-12]) women with BRCA mutant HGSOC (median age 58.7 [44-74.8]) received at least one dose of prexasertib. 13 (59%) patients were secondary platinum-resistant (median 8 [3-12] prior therapies) and 9 (41%) maintained platinum-sensitivity (median 4 [1-5] prior therapies). All but one received prior PARP inhibitor (PARPi) either in combination (10 [48%]) or as monotherapy (11 [52%]), with a median 5 month [mo; 1-29] PARPi-free interval prior to study entry. There was one complete response (41+mo, platinum-sensitive, no prior PARPi) and one partial response (9+mo, platinum-sensitive, 13.5mo PARPi-free interval) yielding an 11% RR (2/18 evaluable). No response was seen in platinum-resistant patients with prior PARPi. Median duration on study treatment was 4mo [1-9] among 21 patients with prior PARPi and 4mo [1.5-9] among 17 evaluable patients with prior PARPi. Common (>10%) grade 3/4 adverse events were neutropenia (82%), leukopenia (64%), and thrombocytopenia (14%); only one patient had grade 3 febrile neutropenia. 16 of 18 (89%) patients with grade 3/4 neutropenia received prophylactic growth factors for subsequent treatments. Conclusions: Prexasertib is tolerable and has modest activity in heavily pretreated BRCA mutant HGSOC patients. Further evaluation of predictive biomarkers for exceptional responders is ongoing. Clinical trial information: NCT02203513.

Germline and Somatic Tumor Testing in Epithelial Ovarian Cancer: ASCO Guideline

PURPOSE

To provide recommendations on genetic and tumor testing for women diagnosed with epithelial ovarian cancer based on available evidence and expert consensus.

METHODS

A literature search and prospectively defined study selection criteria sought systematic reviews, meta-analyses, randomized controlled trials (RCTs), and comparative observational studies published from 2007 through 2019. Guideline recommendations were based on the review of the evidence.

RESULTS

The systematic review identified 19 eligible studies. The evidence consisted of systematic reviews of observational data, consensus guidelines, and RCTs.

RECOMMENDATIONS

All women diagnosed with epithelial ovarian cancer should have germline genetic testing for BRCA1/2 and other ovarian cancer susceptibility genes. In women who do not carry a germline pathogenic or likely pathogenic BRCA1/2 variant, somatic tumor testing for BRCA1/2 pathogenic or likely pathogenic variants should be performed. Women with identified germline or somatic pathogenic or likely pathogenic variants in BRCA1/2 genes should be offered treatments that are US Food and Drug Administration (FDA) approved in the upfront and the recurrent setting. Women diagnosed with clear cell, endometrioid, or mucinous ovarian cancer should be offered somatic tumor testing for mismatch repair deficiency (dMMR). Women with identified dMMR should be offered FDA-approved treatment based on these results. Genetic evaluations should be conducted in conjunction with health care providers familiar with the diagnosis and management of hereditary cancer. First- or second-degree blood relatives of a patient with ovarian cancer with a known germline pathogenic cancer susceptibility gene variant should be offered individualized genetic risk evaluation, counseling, and genetic testing. Clinical decision making should not be made based on a variant of uncertain significance. Women with epithelial ovarian cancer should have testing at the time of diagnosis.

First-in-human phase I study of intraperitoneally administered interferon-activated autologous monocytes in platinum-resistant or refractory ovarian cancer

1

Background: This phase I study evaluated the safety and tolerability of autologous intraperitoneal monocytes treated with SYLATRON (Peginterferon alfa-2b) and ACTIMMUNE (Interferon gamma-1b). Methods: For the dose escalation portion, 3-6 patients with platinum-resistant or refractory ovarian cancer were enrolled into 4 cohorts and treated intraperitoneally (IP) with Peginterferon alfa-2b (25-250 mcg) and Interferon gamma-1b (5-50 mcg), with or without autologous monocytes (75-750 x 106 cells), in order to determine the recommended phase II dose (RP2D). A total of six patients were treated at the RP2D. Patients received the combination of interferons+/- monocytes via IP catheter once every 28 days. Results: 18 patients were enrolled (median age, 61 years; median 5 prior therapies). 1 of 3 patients at the second dose level experienced a dose-limiting toxicity (DLT, grade 3 anemia) and so this cohort was expanded to 6 patients; no subsequent DLTs were observed. The RP2D was defined as 250 mcg/50/mcg/750 x 106 cells on the basis of overall safety and tolerability. The only treatment–related grade 3 or higher adverse events occurring in more than one patient were lymphocyte decrease (33.3%) and abdominal pain (11.1%). Preliminary assessment of efficacy is ongoing. The best response observed has been partial response (PR) in 2/11 evaluable patients, with one patient having a 61% reduction in target lesion size. An additional 4/11 patients had stable disease, and 3 patients remained on treatment for >6 cycles. Exploratory biomarker analyses are ongoing to to further elucidate changes in the immune cell population and correlate with response. An expansion cohort of 10 patients at the RP2D is currently enrolling. Conclusions: This is the first-in-human study of the combination of IP peginterferon alfa-2b, interferon gamma-1b, and autologous monocytes, and the combination displays good tolerability and antitumor activity in a heavily pretreated population, supporting further investigation. Clinical trial information: NCT02948426.

Interferons alpha and gamma with monocytes as a therapeutic strategy for ovarian cancer

9

Background: In the presence of pro-inflammatory cytokines, monocytes are cytotoxic to tumor cells. We previously showed that monocytes stimulated with interferon alpha and gamma result in synergistic killing of ovarian cancer cells in vitro. Here we better characterize monocyte differentiation and their ability to induce cell death through co-culture experiments with spheroids and in mouse xenografts. Methods: OVCAR8 cells were grown in ultra-low attachment conditions for three days before being co-cultured with human monocytes as well as interferon gamma and interferon alpha. Monocytes and OVCAR8s were assayed by flow cytometry for markers of differentiation and viability, respectively. Mouse studies were performed to confirm the viability of human monocytes stimulated with interferon alpha and gamma within the peritoneal cavity seventy-two hours after injection. Subsequent mouse experiments analyzed monocyte differentiation towards M1 or M2 phenotypes by flow cytometry with or without exposure to tumor cells and/or interferons. Results: OVCAR8 spheroids showed decreased viability in the presence of monocytes combined with interferon. We show that monocytes also express a hybrid M1/M2 phenotype when stimulated to IFN and exposed to tumor cells. In mice, monocytes demonstrated a unique differentiation towards both M1 and M2 macrophages as well as plasmacytoid and classic DCs. Various immune cell subsets also differed when comparing peritoneal washes versus tissue digests. Mouse survival studies are ongoing. Conclusions: Monocytes with the combination of interferons alpha and gamma are effective at killing ovarian cancer cells in laboratory models. Phenotypic analyses show a novel pattern of differentiation markers. Our ongoing clinical trial with these agents will incorporate similar studies to correlate monocyte differentiation with anti-tumor activity.

Indirect mechanisms of action of a novel IgG1 monoclonal antibody, NEO-201, to enhance immune killing of tumor

17

Background: NEO-201 is an IgG1 mAb targeting variants of CEACAM5/6 that demonstrates tumor sensitivity and specificity. Functional analysis revealed that NEO-201 is capable of engaging innate immune effector mechanism including ADCC and CDC to directly kill tumor cells expressing its target. Previous studies demonstrated safety/tolerability in non-human primates, and an on going clinical trial at the NCI is currently exploring its dosing and safety. We have explored indirect mechanisms of its action that may enhance immune tumor killing. NEO-201 has the ability to enhance NK activity by blocking the binding of CEACAM5 on tumor cells to CEACAM1 on NK cells. In addition NEO-201 can target and eliminate regulatory T cells (Tregs). Methods: In vitro functional assays, using various human tumor cell lines as target cells and NK-92 cells (CEACAM1+/CD16−) as effectors, were conducted to assess the ability of NEO-201to enhance antitumor cytotoxicity of NK-92 cells by blocking the interaction between CEACAM5 on tumor cells and CEACAM1 on NK cells. In addition, flow cytometry analsyis and CDC assays were performed to evaluate the ability of NEO-201 to target and eliminate human Tregs in vitro. Results: Addition of NEO-201 significantly enhanced NK-92 cell cytotoxicity against highly CEACAM5+/NEO-201+ cells, suggesting that its activity is correlated with the level of CEACAM5+/NEO-201+ tumor cells. Furthermore, NEO-201 targets human Tregs and mediates killing of opsonized T-reg cells via CDC. Conclusions: Previously we have demonstrated the ability of NEO-201 as an IgG1 mab to destroy tumor cells expressing its target directly through both ADCC and CDC. This study suggests that in addition, NEO-201may also mediate immune killing through additional mechanisms including blocking the interaction between CEACAM5 on tumor cells and CEACAM1 on NK cells to reverse CEACAM1-dependent inhibition of NK cytotoxicity. In addition, we have shown that NEO-201 is also able to recognize and eliminate human Tregs. Ongoing studies are looking at leveraging this phenomenon by combining NEO-201 with checkpoint inhibitors.

Phase I with expansion cohorts in a study of NEO-201 in adults with chemo-resistant solid tumors

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Background: NEO-201 is a humanized IgG1 monoclonal antibody (mAb) generated against tumor-associated antigens (TAA) from colorectal cancer. Our preclinical data demonstrated that NEO-201 exerts anti-tumor activity by NK-mediated ADCC and CDC against several tumor types. We identified NEO-201 antigen as a tumor-associated form of CEACAM-5 and -6, which is expressed by tumor tissue but is not present in the surrounding healthy tissue. Methods: This is a first-in-human phase 1 study to determine the maximum tolerated dose (MTD) and recommended phase II dose (RP2D) of NEO-201 in adults with advanced solid tumors that have high likelihood of expression NEO201 antigen and have progressed to standard of treatments. This is a classic 3+3 dose escalation, with cohort expansion at the MTD. NEO-201 is administered intravenously every two weeks, and at four dose levels (DL1 = 1mg/kg, DL2 = 2mg/kg, DL3 = 4mg/kg and DL4 = 6mg/kg). Patients are evaluated for safety according to CTCAEv5.0., and for response according to RECISTv1.1. Biological samples are collected to understand NEO-201 pharmacokinetics, the effects on immune profile and the correlation with treatment toxicity and response. Results: Here we report the safety data and pharmacokinetics from DL1 and 2. A total of 9 evaluable patients were enrolled. Prolonged neutropenia, defined as ³G2 neutropenia lasting for >7 days, was observed at DL2. The cohort was expanded to a total of 6 patients and no further DLTs were observed. Seven out of nine of the patients enrolled had colon cancer, two had pancreatic cancer and one had hormone positive breast cancer. The most frequent treatment-related AEs were infusion reaction which was observed in all patients, and moderate fatigue (33%). Best response was SD observed in two patients (one on each of DL1 and DL2). Dose escalation continues on DL3 and DL4. NEO201 antigen expression in patient tumor tissue, circulating CEACAM6/CEACAM5, and MICA will be evaluated to correlate with response and toxicity. Conclusions: NEO201 has shown some promising activity. PK and PD studies are ongoing to better understand dosing schedule, toxicity profile and to identify biomarkers for patient selection. Clinical trial information: NCT03476681.

The Monoclonal Antibody NEO-201 Enhances Natural Killer Cell Cytotoxicity Against Tumor Cells Through Blockade of the Inhibitory CEACAM5/CEACAM1 Immune Checkpoint Pathway

Background: Natural killer (NK) cells are essential to innate immunity and participate in cancer immune surveillance. Heterophilic interactions between carcinoembryonic antigen (CEA) on tumor cells and carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) on NK cells inhibit NK cell cytotoxicity against tumor cells. NEO-201 is a humanized IgG1 monoclonal antibody that recognizes members of CEACAM family, expressed specifically on a variety of human carcinoma cell lines and tumor tissues. This investigation was designed to determine whether the binding of NEO-201 with CEACAM5 on tumor cells can block the CEACAM5/CEACAM1 interaction to restore antitumor cytotoxicity of NK cells. Materials and Methods: In vitro functional assays, using various human tumor cell lines as target cells and NK-92 cells as effectors, were conducted to assess the ability of NEO-201 to block the interaction between CEACAM5 on tumor cells and CEACAM1 on NK cells to enhance the in vitro killing of tumor cells by NK-92. NK-92 cells were used as a model of direct NK killing of tumor cells because they lack antibody-dependent cellular cytotoxicity activity. Results: Expression profiling revealed that various human carcinoma cell lines expressed different levels of CEACAM5⁺ and NEO-201⁺ cells. Addition of NEO-201 significantly enhanced NK-92 cell cytotoxicity against highly CEACAM5⁺/NEO-201⁺ expressing tumor cells, suggesting that its activity is correlated with the level of CEACAM5⁺/NEO-201⁺ expression. Conclusions: These findings demonstrate that NEO-201 can block the interaction between CEACAM5 on tumor cells and CEACAM1 on NK cells to reverse CEACAM1-dependent inhibition of NK cytotoxicity.

Abstract TMIM-073: THE COMBINATION OF INTERFERONS ALPHA AND GAMMA AND MONOCYTES INDUCES OVARIAN CANCER CELL DEATH AND PROVIDE A RATIONALE FOR A NOVEL, ONGOING, IMMUNOTHERAPY PHASE 1 CLINICAL TRIAL

Standard of care for the treatment of ovarian cancer is surgical tumor debulking, followed by administration of a platinum based compound in combination with a taxane compound. While there is an initial good response to the therapy, especially in optimally debulked tumors, the disease is characterized by a high rate of relapse. There is no definitive second line treatment for patients. Ovarian cancer is largely retained in the peritoneal cavity, with metastases outside of the peritoneum occurring late in the course of the disease. The restriction of the bulk of the tumor burden to the peritoneal cavity makes intraperitoneal (IP) treatment a reasonable approach for ovarian cancer. This strategy was first employed for ovarian cancer using immunotherapy with IP administration of Interferon Alpha. However, one of the hallmarks of ovarian cancer a highly immunosuppressive environment. This environment includes the metastases themselves and the fluid of the peritoneum which contains a mix of pro and anti-inflammatory cells, cytokines and lipids. Tipping the balance towards a pro-inflammatory environment is necessary for the effective treatment of disease.

Herein, we define the mechanisms by which IFNs and monocytes are potent killers of ovarian cancer cells. While patients with ovarian cancer have normal whole blood counts, the tumoricidal activity of their monocytes has never been measured. We demonstrate that ovarian cancer patient monocytes are more tumoricidal when cultured with IFNs than monocytes from sex and age matched controls. In this work, we expand on our previous observations of synergistic killing of ovarian cancer cell lines by monocytes and IFNs by showing that an important mechanism of cell death is mediated by TRAIL expressed on monocytes, and the target cells die in a Caspase-8 dependent mechanism. We also found that the tumoricidal effect of IFNs and monocytes was independent of IRF9 and STAT2 signaling, and was instead dependent on IRF-1 and STAT1 signaling. Together, these data support a new, innate immune based, approach to immunotherapy of ovarian cancer.

We are currently determining the safety of using autologous monocytes treated ex vivo with IFNs and infused into the peritoneal cavity of patients with advanced ovarian cancer in a phase 1 clinical trial (NCT02948426). While the data presented here and previously published works show that innate mediators of the immune system can kill ovarian cancer cells and decrease disease burden, a durable clinical response is dependent on a strong adaptive immune response. In the clinical trial we will identify whether the highly pro-inflammatory properties of the combination of the innate immune effectors monocytes and IFNs can stimulate an existing, but tumor suppressed, adaptive anti-tumor immune response. Here we present a mechanistic understanding of how IFNs and monocytes can kill ovarian cancer cells and provide mechanistic insights into innate immune based immune therapy for the treatment of ovarian cancer.

Citation Format: Daniel S. Green, Chase L. Johnson, Chen-Feng Qi, Kevin W. Tosh, Olena Kamenyeva, Kathryn C. Zoon, Christina M. Annunziata. THE COMBINATION OF INTERFERONS ALPHA AND GAMMA AND MONOCYTES INDUCES OVARIAN CANCER CELL DEATH AND PROVIDE A RATIONALE FOR A NOVEL, ONGOING, IMMUNOTHERAPY PHASE 1 CLINICAL TRIAL [abstract]. In: Proceedings of the 12th Biennial Ovarian Cancer Research Symposium; Sep 13-15, 2018; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2019;25(22 Suppl):Abstract nr TMIM-073.