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

3014

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

6038

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

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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

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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

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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.