Reflections on the state of telehealth and cancer care research and future directions.

Telemedicine has routinely been used in cancer care delivery for the past 3 years. The current state of digital health provides convenience and efficiency for both health-care professional and patient, but challenges exist in equitable access to virtual services. As increasingly newer technologies are added to telehealth platforms, it is essential to eliminate barriers to access through technical, procedural, and legislative improvements. Moving forward, implementation of new strategies can help eliminate disparities in virtual cancer care, facilitate delivery of treatment in the home, and improve real-time data collection for patient safety and clinical trial participation. The ultimate goal will be to extend high-quality survival for all patients with cancer through improved digital delivery of cancer care.

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 ß-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.

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.

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.

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.

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).

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

Smac-mimetic enhances antitumor effect of standard chemotherapy in ovarian cancer models via Caspase 8-independent mechanism.

Ovarian cancer is the most lethal gynecological cancer in the US. Standard treatment consists of surgery followed by chemotherapies relying on apoptotic tumor cell death. Most women with advanced stage disease will relapse, suggesting that this disease is characterized by primary and acquired resistance to chemotherapy, and novel approaches to treatment are greatly needed. Low Caspase 8 expression levels in ovarian cancers correlate with resistance to apoptotic chemotherapy, and a subpopulation of patients with low Caspase 8 levels exhibit poorer overall survival after standard-of-care treatment. We hypothesized that low Caspase 8 function reduces the ability of cancer cells to undergo apoptosis when exposed to standard chemotherapy and that second mitochondria-derived activator of caspases (Smac)-mimetics could increase cell death in combination with chemotherapy. Here we show that combination treatment with a Smac-mimetic can target tumor cells with low Caspase 8 and induce necroptotic cell death. We investigated the in vitro effect of Smac-mimetic added to carboplatin and paclitaxel treatment of ovarian cancer cells expressing wild type and low Caspase 8 levels, which resulted in a 2-4-fold enhancement of cell death. Mice bearing subcutaneous or intraperitoneal ovarian xenografts showed greater aggressiveness of Caspase 8-deficient versus wild-type tumors; combined in vivo treatment with chemotherapy and Smac-mimetic resulted in >50% decrease in low Caspase 8 xenograft growth, as well as significantly enhanced overall survival, especially when given simultaneously with paclitaxel. Surprisingly, Smac-mimetic on the same day as carboplatin decreased mouse survival compared to when it was given on a sequential day of treatment. The antagonism was associated with a decrease in DNA damage markers, emphasizing the importance of optimizing timing of drug administration. Clinical validation of such approaches is needed to increase the effectiveness of current standard ovarian cancer treatment.