Sialyl-Tn serves as a potential therapeutic target for ovarian cancer.

BACKGROUND: Ovarian cancer remains the deadliest of the gynecologic cancers in the United States. There have been limited advances in treatment strategies that have seen marked increases in overall survival. Thus, it is essential to continue developing and validating new treatment strategies and markers to identify patients who would benefit from the new strategy. In this report, we sought to further validate applications for a novel humanized anti-Sialyl Tn antibody-drug conjugate (anti-STn-ADC) in ovarian cancer. METHODS: We aimed to further test a humanized anti-STn-ADC in sialyl-Tn (STn) positive and negative ovarian cancer cell line, patient-derived organoid (PDO), and patient-derived xenograft (PDX) models. Furthermore, we sought to determine whether serum STn levels would reflect STn positivity in the tumor samples enabling us to identify patients that an anti-STn-ADC strategy would best serve. We developed a custom ELISA with high specificity and sensitivity, that was used to assess whether circulating STn levels would correlate with stage, progression-free survival, overall survival, and its value in augmenting CA-125 as a diagnostic. Lastly, we assessed whether the serum levels reflected what was observed via immunohistochemical analysis in a subset of tumor samples. RESULTS: Our in vitro experiments further define the specificity of the anti-STn-ADC. The ovarian cancer PDO, and PDX models provide additional support for an anti-STn-ADC-based strategy for targeting ovarian cancer. The custom serum ELISA was informative in potential triaging of patients with elevated levels of STn. However, it was not sensitive enough to add value to existing CA-125 levels for a diagnostic. While the ELISA identified non-serous ovarian tumors with low CA-125 levels, the sample numbers were too small to provide any confidence the STn ELISA would meaningfully add to CA-125 for diagnosis. CONCLUSIONS: Our preclinical data support the concept that an anti-STn-ADC may be a viable option for treating patients with elevated STn levels. Moreover, our STn-based ELISA could complement IHC in identifying patients with whom an anti-STn-based strategy might be more effective.

Targeting Galectin 3 illuminates its contributions to the pathology of uterine serous carcinoma.

BACKGROUND: Uterine serous cancer (USC) comprises around 10% of all uterine cancers. However, USC accounts for approximately 40% of uterine cancer deaths, which is attributed to tumor aggressiveness and limited effective treatment. Galectin 3 (Gal3) has been implicated in promoting aggressive features in some malignancies. However, Gal3's role in promoting USC pathology is lacking. METHODS: We explored the relationship between LGALS3 levels and prognosis in USC patients using TCGA database, and examined the association between Gal3 levels in primary USC tumors and clinical-pathological features. CRISPR/Cas9-mediated Gal3-knockout (KO) and GB1107, inhibitor of Gal3, were employed to evaluate Gal3's impact on cell function. RESULTS: TCGA analysis revealed a worse prognosis for USC patients with high LGALS3. Patients with no-to-low Gal3 expression in primary tumors exhibited reduced clinical-pathological tumor progression. Gal3-KO and GB1107 reduced cell proliferation, stemness, adhesion, migration, and or invasion properties of USC lines. Furthermore, Gal3-positive conditioned media (CM) stimulated vascular tubal formation and branching and transition of fibroblast to cancer-associated fibroblast compared to Gal3-negative CM. Xenograft models emphasized the significance of Gal3 loss with fewer and smaller tumors compared to controls. Moreover, GB1107 impeded the growth of USC patient-derived organoids. CONCLUSION: These findings suggest inhibiting Gal3 may benefit USC patients.

Structural basis for antibody recognition of the proximal MUC16 ectodomain.

BACKGROUND: Mucin 16 (MUC16) overexpression is linked with cancer progression, metastasis, and therapy resistance in high grade serous ovarian cancer and other malignancies. The cleavage of MUC16 forms independent bimodular fragments, the shed tandem repeat sequence which circulates as a protein bearing the ovarian cancer biomarker (CA125) and a proximal membrane-bound component which is critical in MUC16 oncogenic behavior. A humanized, high affinity antibody targeting the proximal ectodomain represents a potential therapeutic agent against MUC16 with lower antigenic potential and restricted human tissue expression. RESULTS: Here, we demonstrate the potential therapeutic versatility of the humanized antibody as a monoclonal antibody, antibody drug conjugate, and chimeric antigen receptor. We report the crystal structures of 4H11-scFv, derived from an antibody specifically targeting the MUC16 C-terminal region, alone and in complex with a 26-amino acid MUC16 segment resolved at 2.36 Å and 2.47 Å resolution, respectively. The scFv forms a robust interaction with an epitope consisting of two consecutive ß-turns and a ß-hairpin stabilized by 2 hydrogen bonds. The VH-VL interface within the 4H11-scFv is stabilized through an intricate network of 11 hydrogen bonds and a cation-π interaction. CONCLUSIONS: Together, our studies offer insight into antibody-MUC16 ectodomain interaction and advance our ability to design agents with potentially improved therapeutic properties over anti-CA125 moiety antibodies.

Dual Fluorescence Isogenic Synthetic Lethal Kinase Screen and High-Content Secondary Screening for MUC16/CA125-Selective Agents.

Significant strides have been made in the development of precision therapeutics for cancer. Aberrantly expressed glycoproteins represent a potential avenue for therapeutic development. The MUC16/CA125 glycoprotein serves as a biomarker of disease and a driver of malignant transformation in epithelial ovarian cancer. Previously, we demonstrated a proof-of-principle approach to selectively targeting MUC16+ cells. In this report, we performed a synthetic lethal kinase screen using a human kinome RNAi library and identified key pathways preferentially targetable in MUC16+ cells using isogenic dual-fluorescence ovarian cancer cell lines. Using a separate approach, we performed high-content small-molecule screening of six different libraries of 356,982 compounds for MUC16/CA125-selective agents and identified lead candidates that showed preferential cytotoxicity in MUC16+ cells. Compounds with differential activity were selected and tested in various other ovarian cell lines or isogenic pairs to identify lead compounds for structure-activity relationship (SAR) selection. Lead siRNA and small-molecule inhibitor candidates preferentially inhibited invasion of MUC16+ cells in vitro and in vivo, and we show that this is due to decreased activation of MAPK, and non-receptor tyrosine kinases. Taken together, we present a comprehensive screening approach to the development of a novel class of MUC16-selective targeted therapeutics and identify candidates suitable for further clinical development.

Effect of Mismatch Repair Status on Outcome of Early-Stage Grade 1 to 2 Endometrial Cancer Treated With Vaginal Brachytherapy.

OBJECTIVES: The objective of this study was to determine if deficiency of mismatch repair (dMMR) proteins in patients with early-stage favorable endometrial cancer treated with vaginal brachytherapy (VB) is associated with increased recurrence. MATERIALS AND METHODS: A multi-institutional retrospective cohort study of 141 patients with stage I to II grade 1 and 2 endometrioid adenocarcinoma treated with surgery and adjuvant VB was performed to compare recurrence risk in dMMR (n=41) versus MMR-preserved (pMMR) (n=100). Additional clinical and pathologic risk factors were also collected. Univariate analysis and multivariable analysis Cox regression analysis was performed to identify factors associated with any recurrence. Kaplan-Meier method and log rank test were used to compare recurrence free survival and overall survival (OS). RESULTS: Median follow up was 42 months. Forty-one patients (29%) were dMMR. There were 7 recurrences (17%) in dMMR versus 4 recurrences (4%) in pMMR (P=0.009). On univariate analysis of any recurrence, both dMMR (hazard ratio: 5.3, P=0.008) and stage (hazard ratio: 3.8, P=0.05) were statistically significantly associated with time to first recurrence. The 5-year recurrence free survival was 90% (95% CI: 73%-96%) in pMMR versus 61.0% (95% CI: 19%-86%) in dMMR (P=0.003). Five-year OS was 96% (95% CI: 76%-99%) in pMMR versus 86% (95% CI: 62%-95%) in dMMR (P=0.03). CONCLUSIONS: MMR deficiency in stage I to II grade 1 to 2 endometrial cancer patients treated with adjuvant VB alone was associated with statistically significant increased risk for any recurrence and worse OS. MMR status may be an important prognosticator in this cohort of patients warranting adjuvant treatment intensification in the clinical trial setting.

Antibody-Peptide Epitope Conjugates for Personalized Cancer Therapy.

Antibody-peptide epitope conjugates (APEC) are a new class of modified antibody-drug conjugates that redirect T-cell viral immunity against tumor cells. APECs contain a tumor-specific protease cleavage site linked to a patient-specific viral epitope, resulting in presentation of viral epitopes on cancer cells and subsequent recruitment and killing by CD8+ T cells. Here we developed an experimental pipeline to create patient-specific APECs and identified new preclinical therapies for ovarian carcinoma. Using functional assessment of viral peptide antigen responses to common viruses like cytomegalovirus (CMV) in patients with ovarian cancer, a library of 192 APECs with distinct protease cleavage sequences was created using the anti-epithelial cell adhesion molecule (EpCAM) antibody. Each APEC was tested for in vitro cancer cell killing, and top candidates were screened for killing xenograft tumors grown in zebrafish and mice. These preclinical modeling studies identified EpCAM-MMP7-CMV APEC (EpCAM-MC) as a potential new immunotherapy for ovarian carcinoma. Importantly, EpCAM-MC also demonstrated robust T-cell responses in primary ovarian carcinoma patient ascites samples. This work highlights a robust, customizable platform to rapidly develop patient-specific APECs. SIGNIFICANCE: This study develops a high-throughput preclinical platform to identify patient-specific antibody-peptide epitope conjugates that target cancer cells and demonstrates the potential of this immunotherapy approach for treating ovarian carcinoma.

Addressing cervical cancer screening disparities through advances in artificial intelligence and nanotechnologies for cellular profiling.

Almost all cases of cervical cancer are caused by the human papilloma virus (HPV). Detection of pre-cancerous cervical changes provides a window of opportunity for cure of an otherwise lethal disease when metastatic. With a greater understanding of the biology and natural course of high-risk HPV infections, screening methods have shifted beyond subjective Pap smears toward more sophisticated and objective tactics. This has led to a substantial growth in the breadth and depth of HPV-based cervical cancer screening tests, especially in developed countries without constrained resources. Many low- and middle-income countries (LMICs) have less access to advanced laboratories and healthcare resources, so new point-of-care (POC) technologies have been developed to provide test results in real time, improve the efficiency of techniques, and increase screening adoption. In this Review, we will discuss how novel decentralized screening technologies and computational strategies improve upon traditional methods and how their realized promise could further democratize cervical cancer screening and promote greater disease prevention.

Targeting galectin-3 with a high-affinity antibody for inhibition of high-grade serous ovarian cancer and other MUC16/CA-125-expressing malignancies.

The lectin, galectin-3 (Gal3), has been implicated in a variety of inflammatory and oncogenic processes, including tumor growth, invasion, and metastasis. The interactions of Gal3 and MUC16 represent a potential targetable pathway for the treatment of MUC16-expressing malignancies. We found that the silencing of Gal3 in MUC16-expressing breast and ovarian cancer cells in vitro inhibited tumor cell invasion and led to attenuated tumor growth in murine models. We therefore developed an inhibitory murine monoclonal anti-Gal3 carbohydrate-binding domain antibody, 14D11, which bound human and mouse Gal3 but did not bind human Galectins-1, -7, -8 or -9. Competition studies and a docking model suggest that the 14D11 antibody competes with lactose for the carbohydrate binding pocket of Gal3. In MUC16-expressing cancer cells, 14D11 treatment blocked AKT and ERK1/2 phosphorylation, and led to inhibition of cancer cell Matrigel invasion. Finally, in experimental animal tumor models, 14D11 treatment led to prolongation of overall survival in animals bearing flank tumors, and retarded lung specific metastatic growth by MUC16 expressing breast cancer cells. Our results provide evidence that antibody based Gal3 blockade may be a viable therapeutic strategy in patients with MUC16-expressing tumors, supporting further development of human blocking antibodies against Gal3 as potential cancer therapeutics.

Galectins and Ovarian Cancer.

Ovarian cancer is known for its aggressive pathological features, including the capacity to undergo epithelial to mesenchymal transition, promoting angiogenesis, metastatic potential, chemoresistance, inhibiting apoptosis, immunosuppression and promoting stem-like features. Galectins, a family of glycan-binding proteins defined by a conserved carbohydrate recognition domain, can modulate many of these processes, enabling them to contribute to the pathology of ovarian cancer. Our goal herein was to review specific galectin members identified in the context of ovarian cancer, with emphasis on their association with clinical and pathological features, implied functions, diagnostic or prognostic potential and strategies being developed to disrupt their negative actions.

Radiopharmacologic screening of antibodies to the unshed ectodomain of MUC16 in ovarian cancer identifies a lead candidate for clinical translation.

INTRODUCTION: Despite its limitations, CA125 remains the most widely used biomarker for the diagnosis and treatment monitoring of ovarian cancer. Targeting the unshed portion of serum biomarkers such as CA125/MUC16 may afford more specific imaging and targeting of MUC16-positive tumors in High Grade Serous Ovarian Cancer (HGSOC) patients. METHODS: Six monoclonal antibodies raised against the 58 amino acid sequence between the extracellular cleavage site and the transmembrane region of MUC16 were radiolabeled with [89Zr]Zr4+. The radioimmunoconjugates were evaluated in vitro for molar activities, target binding affinity, cellular internalization and serum stability. In vivo characterization was performed via longitudinal positron emission tomography (PET) imaging and ex vivo biodistribution studies in mice bearing subcutaneous xenografts of SKOV3 cells transfected with the proximal 114 amino-acids of MUC16 carboxy-terminus (SKOV3+). RESULTS: In vitro screening identified 9C9 and 4H11 as the lead antibody candidates based on their comparable binding affinities, serum stability and cellular internalization profiles. Despite an identical molecular footprint for binding to MUC16, [89Zr]Zr-DFO-4H11 yielded a more favorable in vivo radiopharmacologic profile. Furthermore, a humanized variant of 4H11 capable of binding MUC16 in vitro also yielded excellent in vivo profile in subcutaneous xenograft models of SKOV3+, OVCAR3 tumors and a patient-derived xenograft model representative of HGSOC. CONCLUSION: Radiopharmacologic screening of antibodies early during their development can provide crucial information pertinent to the in vitro characterization and in vivo pharmacokinetics. The favorable in vivo profile demonstrated by humanized 4H11 combined with the use of its murine predecessor for immunohistochemical staining of biopsied tumor tissues from HGSOC patients makes a unique pair of antibodies that is poised for clinical translation.

The Metabolic Inhibitor CPI-613 Negates Treatment Enrichment of Ovarian Cancer Stem Cells.

One of the most significant therapeutic challenges in the treatment of ovarian cancer is the development of recurrent platinum-resistant disease. Cancer stem cells (CSCs) are postulated to contribute to recurrent and platinum-resistant ovarian cancer (OvCa). Drugs that selectively target CSCs may augment the standard of care cytotoxics and have the potential to prevent and/or delay recurrence. Increased reliance on metabolic pathway modulation in CSCs relative to non-CSCs offers a possible therapeutic opportunity. We demonstrate that treatment with the metabolic inhibitor CPI-613 (devimistat, an inhibitor of tricarboxylic acid (TCA) cycle) in vitro decreases CD133+ and CD117+ cell frequency relative to untreated OvCa cells, with negligible impact on non-CSC cell viability. Additionally, sphere-forming capacity and tumorigenicity in vivo are reduced in the CPI-613 treated cells. Collectively, these results suggest that treatment with CPI-613 negatively impacts the ovarian CSC population. Furthermore, CPI-613 impeded the unintended enrichment of CSC following olaparib or carboplatin/paclitaxel treatment. Collectively, our results suggest that CPI-613 preferentially targets ovarian CSCs and could be a candidate to augment current treatment strategies to extend either progression-free or overall survival of OvCa.

Critical questions in ovarian cancer research and treatment: Report of an American Association for Cancer Research Special Conference.

Substantial progress has been made in understanding ovarian cancer at the molecular and cellular level. Significant improvement in 5-year survival has been achieved through cytoreductive surgery, combination platinum-based chemotherapy, and more effective treatment of recurrent cancer, and there are now more than 280,000 ovarian cancer survivors in the United States. Despite these advances, long-term survival in late-stage disease has improved little over the last 4 decades. Poor outcomes relate, in part, to late stage at initial diagnosis, intrinsic drug resistance, and the persistence of dormant drug-resistant cancer cells after primary surgery and chemotherapy. Our ability to accelerate progress in the clinic will depend on the ability to answer several critical questions regarding this disease. To assess current answers, an American Association for Cancer Research Special Conference on "Critical Questions in Ovarian Cancer Research and Treatment" was held in Pittsburgh, Pennsylvania, on October 1-3, 2017. Although clinical, translational, and basic investigators conducted much of the discussion, advocates participated in the meeting, and many presentations were directly relevant to patient care, including treatment with poly adenosine diphosphate ribose polymerase (PARP) inhibitors, attempts to improve immunotherapy by overcoming the immune suppressive effects of the microenvironment, and a better understanding of the heterogeneity of the disease.

Losartan treatment enhances chemotherapy efficacy and reduces ascites in ovarian cancer models by normalizing the tumor stroma.

In ovarian cancer patients, tumor fibrosis and angiotensin-driven fibrogenic signaling have been shown to inversely correlate with survival. We sought to enhance drug delivery and therapeutic efficacy by remodeling the dense extracellular matrix in two orthotopic human ovarian carcinoma xenograft models. We hypothesized that targeting the angiotensin signaling axis with losartan, an approved angiotensin system inhibitor, could reduce extracellular matrix content and the associated "solid stress," leading to better anticancer therapeutic effect. We report here four translatable findings: (i) losartan treatment enhances the efficacy of paclitaxel-a drug used for ovarian cancer treatment-via normalizing the tumor microenvironment, resulting in improved vessel perfusion and drug delivery; (ii) losartan depletes matrix via inducing antifibrotic miRNAs that should be tested as candidate biomarkers of response or resistance to chemotherapy; (iii) although losartan therapy alone does not reduce tumor burden, it reduces both the incidence and the amount of ascites formed; and (iv) our retrospective analysis revealed that patients receiving angiotensin system inhibitors concurrently with standard treatment for ovarian cancer exhibited 30 mo longer overall survival compared with patients on other antihypertensives. Our findings provide the rationale and supporting data for a clinical trial on combined losartan and chemotherapy in ovarian cancer patients.

Clinical Utility of Prospective Molecular Characterization in Advanced Endometrial Cancer.

PURPOSE: Advanced-stage endometrial cancers have limited treatment options and poor prognosis, highlighting the need to understand genetic drivers of therapeutic vulnerabilities and/or prognostic predictors. We examined whether prospective molecular characterization of recurrent and metastatic disease can reveal grade and histology-specific differences, facilitating enrollment onto clinical trials. EXPERIMENTAL DESIGN: We integrated prospective clinical sequencing and IHC data with detailed clinical and treatment histories for 197 tumors, profiled by MSK-IMPACT from 189 patients treated at Memorial Sloan Kettering Cancer Center. RESULTS: Patients had advanced disease and high-grade histologies, with poor progression-free survival on first-line therapy (PFS1). When matched for histology and grade, the genomic landscape was similar to that of primary untreated disease profiled by TCGA. Using multiple complementary genomic and mutational signature-based methods, we identified patients with microsatellite instability (MSI), even when standard MMR protein IHC staining failed. Tumor and matched normal DNA sequencing identified rare pathogenic germline mutations in BRCA2 and MLH1. Clustering the pattern of DNA copy-number alterations revealed a novel subset characterized by heterozygous losses across the genome and significantly worse outcomes compared with other clusters (median PFS1 9.6 months vs. 17.0 and 17.4 months; P = 0.006). Of the 68% of patients harboring potentially actionable mutations, 27% were enrolled to matched clinical trials, of which 47% of these achieved clinical benefit. CONCLUSIONS: Prospective clinical sequencing of advanced endometrial cancer can help refine prognosis and aid treatment decision making by simultaneously detecting microsatellite status, germline predisposition syndromes, and potentially actionable mutations. A small overall proportion of all patients tested received investigational, genomically matched therapy as part of clinical trials.

A Randomized Trial of Prophylactic Extended Carboplatin Infusion to Reduce Hypersensitivity Reactions in Recurrent Ovarian Cancer.

OBJECTIVE: Hypersensitivity with repeated exposure to platinum agents is common and can preclude continued treatment, even in patients with disease that remains platinum sensitive. We sought to compare the effects of prophylactic, extended carboplatin infusion versus standard infusion on the rate of carboplatin hypersensitivity reactions (HSRs) in women with recurrent ovarian cancer. METHODS: This was a single-institution, randomized, nonblinded trial comparing a graded, 3-hour extended infusion of carboplatin with a standard 30-minute infusion in patients with recurrent ovarian cancer who were enrolled from January 2011 to April 2015. The study was designed to detect a decrease in the HSR rate from 20% (standard infusion) to 5% (extended infusion) assuming a type 1 error of 10% and power of 80% using a 1-sided test. RESULTS: Of 146 enrolled patients, 114 were evaluable. Fifteen (13%) had an HSR-11% (6/56) in the extended-infusion and 16% (9/58) in the standard-infusion groups (P = 0.582). Planned treatment completion was achieved in 50 (89%) of 56 patients and 49 (84%) of 58 patients, respectively. Of 25 patients who received single-agent carboplatin, 8 (32%) had an HSR (53% of all patients who had an HSR [8/15]). Of 23 patients who received carboplatin with gemcitabine, 4 (17%) had an HSR (27% of all patients who had an HSR [4/15]). Of 8 patients who received carboplatin with paclitaxel, 3 (38%) had an HSR (20% of all patients who had an HSR [3/15]). There were no HSRs with pegylated liposomal doxorubicin, the most commonly given concurrent chemotherapy (46% of all patients). CONCLUSIONS: A prophylactic, extended carboplatin infusion was not associated with a decreased HSR rate. The overall low HSR rate suggests that premedication may help reduce HSRs.

Impact of race on dose selection of molecular-targeted agents in early-phase oncology trials.

BACKGROUND: We examined the impact of race on the maximum tolerated doses (MTD) and final approved doses (FAD) of single-agent molecular-targeted agents (MTA) in North America/Europe (NA/EU) and Asia. METHODS: We searched PubMed and regulatory databases to identify targeted drugs approved globally and compared their FAD and MTD in corresponding phase I/II studies conducted separately in NA/EU and Asia. To evaluate this further, we conducted parallel, prospective, first-in-human studies of DS-7423, a dual PI3K/mTOR inhibitor, in patients with advanced solid tumours in the US and Japan. We pooled and compared the pharmacokinetics (PK), pharmacodynamics (PD), toxicity, and efficacy between these populations. RESULTS: 17 MTA were approved in NA/EU and Asia from 2001 to 2015. Recommended phase 2 doses (RP2D) were identical across races in 14 of 17 (80%) studies and differences were not clinically meaningful. FAD were identical across all regions. 42 and 27 patients from US and Japan, respectively, were enrolled in the phase I studies of DS-7423. Despite differences in race, body weight, and body mass index, the RP2D were 240 mg/day with no differences in toxicities, PK, PD, or efficacy. CONCLUSIONS: Conducting separate clinical trials of single-agent MTA in Caucasian and Asian populations may be redundant.