Kristin Bixel

Use and Effectiveness of Neoadjuvant Chemotherapy for Treatment of Ovarian Cancer

Purpose In 2010, a randomized clinical trial demonstrated noninferior survival for patients with advanced ovarian cancer who were treated with neoadjuvant chemotherapy (NACT) compared with primary cytoreductive surgery (PCS). We examined the use and effectiveness of NACT in clinical practice. Patients and Methods A multi-institutional observational study of 1,538 women with stages IIIC to IV ovarian cancer who were treated at six National Cancer Institute-designated cancer centers. We examined NACT use in patients who were diagnosed between 2003 and 2012 (N = 1,538) and compared overall survival (OS), morbidity, and postoperative residual disease in a propensity-score matched sample of patients (N = 594). Results NACT use increased from 16% during 2003 to 2010 to 34% during 2011 to 2012 in stage IIIC disease ( Ptrend < .001), and from 41% to 62% in stage IV disease ( Ptrend < .001). Adoption of NACT varied by institution, from 8% to 30% for stage IIIC disease (P < .001) and from 27% to 61% ( P = .007) for stage IV disease during this time period. In the matched sample, NACT was associated with shorter OS in stage IIIC disease (median OS: 33 v 43 months; hazard ratio [HR], 1.40; 95% CI, 1.11 to 1.77) compared with PCS, but not stage IV disease (median OS: 31 v 36 months; HR, 1.16; 95% CI, 0.89 to 1.52). Patients with stages IIIC and IV disease who received NACT were less likely to have ≥ 1 cm postoperative residual disease, an intensive care unit admission, or a rehospitalization (all P ≤ .04) compared with those who received PCS treatment. However, among women with stage IIIC disease who achieved microscopic or ≤ 1 cm postoperative residual disease, NACT was associated with decreased OS (HR, 1.49; 95% CI, 1.01 to 2.18; P = .04). Conclusion Use of NACT increased significantly between 2003 and 2012. In this observational study, PCS was associated with increased survival in stage IIIC, but not stage IV disease. Future studies should prospectively consider the efficacy of NACT by extent of residual disease in unselected patients.

Elevated STAT3 expression in ovarian cancer ascites promotes invasion and metastasis: A potential therapeutic target

Although activation of the STAT3 pathway has been associated with tumor progression in a wide variety of cancer types (including ovarian cancer), the precise mechanism of invasion and metastasis due to STAT3 are not fully delineated in ovarian cancer. We found that pSTAT3 Tyr705 is constitutively activated in patient ascites and ascites-derived ovarian cancer cells (ADOCCs), and the range of STAT3 expression could be very high to low. In vivo transplantation of ADOCCs with high pSTAT3 expression into the ovarian bursa of mice resulted in a large primary tumor and widespread peritoneal metastases. In contrast, ADOCCs with low STAT3 expression or ADOCCs with STAT3 expression knockdown, led to reduced tumor growth and an absence of metastases in vivo. Cytokines derived from the ADOCC culture medium activate the interleukin (IL)-6/STAT pathway in the STAT3 knockout (KO) cells, compensating for the absence of inherent STAT3 in the cells. Treatment with HO-3867 (a novel STAT3 inhibitor at 100 p.p.m. in an orthotopic murine model) significantly suppressed ovarian tumor growth, angiogenesis and metastasis by targeting STAT3 and its downstream proteins. HO-3867 was found to have cytotoxic effects in ex vivo cultures of freshly collected human ovarian cancers, including those resistant to platinum-based chemotherapy. Our results show that STAT3 is necessary for ovarian tumor progression/metastasis and highlight the potential for targeting STAT3 by HO-3867 as a therapeutic strategy for ovarian cancer.

Olaparib in the management of ovarian cancer

Alterations in the homologous repair pathway are thought to occur in 30%–50% of epithelial ovarian cancers. Cells deficient in homologous recombination rely on alternative pathways for DNA repair in order to survive, thereby providing a potential target for therapy. Olaparib, a poly(ADP-ribose) polymerase (PARP) inhibitor, capitalizes on this concept and is the first drug in its class approved for patients with ovarian cancer. This review article will provide an overview of the BRCA genes and homologous recombination, the role of PARP in DNA repair and the biological rationale for the use of PARP inhibitors as cancer therapy, and ultimately will focus on the use of olaparib in the management of ovarian cancer.

PARP inhibition and gynecologic malignancies: A review of current literature and on-going trials

The poly (ADP-ribose) polymerase (PARP) family of enzymes is important in several DNA repair pathways. Drugs that inhibit these enzymes have been investigated in many types of cancer, but their application in the treatment of gynecologic malignancies has rapidly evolved - as manifested by the 2014 FDA approval for olaparib in the treatment of recurrent ovarian cancer associated with a germline BRCA mutation (gBRCA). In efforts to broaden their efficacy, current clinical trials have demonstrated benefit of olaparib, and other PARP inhibitors (PARPi), as single agents and in combination with cytotoxic chemotherapy and biologic agents, in wide ranging populations. Although the majority of data for PARPi in gynecologic malignancies has been specifically regarding ovarian cancer, their role in the treatment of uterine and cervical cancer is currently being investigated. This review will serve as a synopsis of seminal trials to date, summarize the breadth of clinical application in on-going studies, query how these results may change future practice, and reflect on questions yet to be answered.

Targeting STAT3 by HO3867 induces apoptosis in ovarian clear cell carcinoma

Advanced ovarian clear cell carcinoma (OCCC) carries a very poor prognosis in large part secondary to the extremely high rate of resistance to standard platinum and taxane chemotherapy. Signal transducer and activator of transcription 3(STAT3) expression and activation has been shown to regulate tumor progression in various human cancers, though has not been well studied in OCCC. Preliminary work in our lab has demonstrated constitutive activation of STAT3 (pSTAT3Tyr705 or pSTAT3727) in OCCC cell lines as well as human OCCC tumor tissue samples. Significantly, pSTAT3 is expressed in the absence of other forms of activated STAT (pSTAT1, 2, 6). Therefore, this work was planned to investigate the role of STAT3 and examine the efficacy of a novel anti‐cancer compound ‐HO‐3867, which is an inhibitor of STAT3, using known OCCC cell lines. Results demonstrate that treatment with HO‐3867 decreased expression of pSTAT3 Tyr705 as well pSTAT3 Ser727, while total STAT3 remained constant. STAT3 overexpression increased the migration capability in OVTOKO cells in vitro and led to an increased tumor size when injected in vivo. The inhibitory effect of HO‐3867 on cell proliferation and cell survival was accompanied by increased apoptosis, within 24 h post treatment. Treatment with HO‐3867 resulted in a decrease in Bcl‐2 and increase of cleavage of caspase 3, caspase 7, and PARP, confirming induction of apoptosis after treatment with HO‐3867. In addition, HO‐3867 significantly inhibited formation of human umbilical vein endothelial cells capillary‐like structures and invasion at both 5 and 10 µM concentrations. STAT3 expression plays an important role in the spread of OCCC in vitro as well as in vivo. Thus, we can exploit the STAT3 pathway for targeted drug therapy. Inhibition of pSTAT3 using HO‐3867in OCCC cell lines appears to be a promising therapy. This is of utmost importance given the poor response of OCCC to standard chemotherapy regimens.

STAT3/PIAS3 Levels Serve as “Early Signature” Genes in the Development of High-Grade Serous Carcinoma from the Fallopian Tube

The initial molecular events that lead to malignant transformation of the fimbria of the fallopian tube (FT) through high-grade serous ovarian carcinoma (HGSC) remain poorly understood. In this study, we report that increased expression of signal transducer and activator of transcription 3 (pSTAT3 Tyr705) and suppression or loss of protein inhibitor of activated STAT3 (PIAS3) in FT likely drive HGSC. We evaluated human tissues-benign normal FT, tubal-peritoneal junction (TPJ), p53 signature FT tissue, tubal intraepithelial lesion in transition (TILT), serous tubal intraepithelial carcinoma (STIC) without ovarian cancer, and HGSC for expression of STAT3/PIAS3 (compared with their known TP53 signature) and their target proliferation genes. We observed constitutive activation of STAT3 and low levels or loss of PIAS3 in the TPJ, p53 signature, TILT, and STIC through advanced stage IV (HGSC) tissues. Elevated expression of pSTAT3 Tyr705 and decreased levels of PIAS3 appeared as early as TPJ and the trend continued until very advanced stage HGSC (compared with high PIAS3 and low pSTAT3 expression in normal benign FT). Exogenous expression of STAT3 in FT cells mediated translocation of pSTAT3 and c-Myc into the nucleus. In vivo experiments demonstrated that overexpression of STAT3 in FT secretory epithelial cells promoted tumor progression and metastasis, mimicking the clinical disease observed in patients with HGSC. Thus, we conclude that the STAT3 pathway plays a role in the development and progression of HGSC from its earliest premalignant states.Significance: Concomitant gain of pSTAT3 Tyr705 and loss of PIAS3 appear critical for initiation and development of high-grade serous carcinoma. Cancer Res; 78(7); 1739-50. ©2018 AACR.

Recurrent low grade serous ovarian cancer in a 20 year old woman: A case from the Ohio State University College of Medicine

A 20 year old with recurrent low-grade serous carcinoma (LGSC) is discussed. The differential diagnosis, pathology, epidemiology, treatment options are discussed. Focus on the molecular pathways of LGSC and the implications of the diagnosis on fertility are highlighted.

Abstract LB-036: Elevated STAT3 expression in ovarian tumor ascites regulates invasion and metastasis: a promising therapeutic target

Objectives: Although, the ovarian cancer patient ascites is a recognized source of metastasis, the expression of oncogenic proteins in ascites and their effects on the tumor metastatic microenvironment still remain poorly understood. In this study, we investigate the role of STAT3 in primary ovarian cancer ascites and STAT3 as a potential target for ovarian tumor therapy in a preclinical animal model using our novel and safe STAT3 inhibitor of HO-3867. Methods: We start with culturing the primary cancer cell lines from various human ascites and confirming the status of STAT3 signaling. The exact role that STAT3 plays in ovarian cancer was addressed using STAT3 knocked down and STAT3 overexpression cell lines. These were further used to develop an orthotopic mouse model of ovarian cancer. In vivo antitumor activity of STAT3 inhibitor of HO-3867 assessment was done by oral administration of HO-3867 in orthotopic tumor mice. using histopathological analysis, RPPA, TUNEL and angiogenesis assays. In vivo bio-absorption of HO-3867 compounds in tumors by EPR and LCMS analysis. Results: We have found that pSTAT3 Tyr705 is constitutively expressed in the patient ascites derived cancer cells (ADCCs) and the range of expression could be very high to low. Subsequent in vivo transplantation of ADCCs with higher pSTAT3 expression injected into mice resulted in a large primary tumor and widespread metastases; while the mice with cells with STAT3 Knocked out had a smaller tumor and no metastases. We further demonstrate that the cytokines secreted into the culture medium can activate the JAK/STAT pathway in the STAT3 Ko cells thereby making up for the absence of inherent STAT3 in the cells. Once we proved the importance of STAT3 in ovarian cancer progression and metastases, we moved on to targeting STAT3 using our novel STAT3 inhibitor and pre-clinical orthotopic tumor model. Treatment with HO-3867 (100 ppm) significantly suppressed ovarian tumor growth and metastasis. A substantial amount of HO-3867 was detected in the ovarian tumor tissues. Suppression of STAT3 and its downstream target proteins were confirmed with reverse phase protein array. In vivo Matrigel assay showed that HO-3867 treated samples had significantly reduced vessel formation (∼4 times) when compared to untreated control. HO-3867 was also found to have cytotoxic effects in ex vivo culture of freshly collected human tumor samples, including patients with chemotherapy-resistant disease. Conclusions: Our study has concluded that constitutive expression of STAT3 in patient ascites is a significant contributor in ovarian tumor invasion and metastasis. STAT3-selective targeting agent HO-3867 in orthotopic ovarian tumor and ex vivo tumor tissue culture, results in inhibition of tumor growth and induction of apoptosis both in vivo and ex vivo, suggesting that HO-3867 is an exciting new cytotoxic agent acting through targeting STAT3; which could have a considerable role in the future treatment of ovarian cancer. Citation Format: Uksha Saini, Shan Naidu, Adam C. ElNaggar, Hemant K. Bid, John Wallbillich, Ross Wanner, Kristin Bixel, Maria Riley, Chelsea Bolyard, Adrian A. Suarez, Balveen Kaur, Periannan Kuppusamy, John Hays, Paul Goodfellow, David E. Cohn, Karuppaiyah Selvendiran. Elevated STAT3 expression in ovarian tumor ascites regulates invasion and metastasis: a promising therapeutic target. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-036.

Abstract 5405: Targeting STAT3 as a novel therapy for ovarian clear cell carcinoma

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA Objective: Advanced ovarian clear cell carcinoma (OCCC) carries a very poor prognosis in large part secondary to the high rate of resistance to standard platinum and taxane chemotherapy. STAT3 expression and activation has been shown to regulate tumor progression in various human cancers though has not been well studied in OCCC. Preliminary work in our lab has demonstrated constitutive activation of STAT3 (pSTAT3Tyr705 or pSTAT3727) in OCCC cell lines as well as human OCCC tumor tissue samples. Significantly, pSTAT3 is expressed in the absence of other forms of activated STAT (pSTAT1,2,6). Based on our preliminary data, we hypothesized that use of a novel STAT3 inhibitor, HO-3867, would be an effective agent against OCCC cell lines in vitro and in vivo using a novel orthotopic mouse model. Methods: Five OCCC cell lines (JHOC, OVISE, OVTOKO, RMGV, and ES2) were treated with HO-3867, cisplatin, or paclitaxel alone and/or in combination. Protein expression in tumor tissue and cell lines was determined by western blot (WB) and RT PCR was used to analyze RNA expression levels. MTT assay, BrdU assay, ANNEXIN V kit and flow cytometry were used to analyze cell viability, proliferation, apoptosis and cell cycle arrest. We use a novel orthotopic murine model using an ovarian bursal injection which was developed in our laboratory and has demonstrated primary ovarian tumor development and peritoneal carcinomatosis. Results: Treatment with HO-3867 decreased expression of pSTAT3 while total STAT3 remained constant. Treatment with cisplatin or paclitaxel resulted in a relative increase in pSTAT3. The inhibitory effect of HO-3867 on cell proliferation is associated with G2/M phase cell cycle arrest and apoptosis (>45%) within 24 hours of treatment. Treatment with HO-3867 resulted in a decrease in BCL2 and cleavage of caspase 3, caspase 7, and PARP confirming induction of apoptosis after treatment with HO-3867. Treatment with cisplatin or paclitaxel was less effective at decreasing cell viability, reducing proliferation, and inducing apoptosis. In vivo experiments using the orthotopic murine model are ongoing. Conclusion: HO-3867, a novel STAT3 inhibitor, appears to be efficacious against OCCC in vitro as compared to standard chemotherapeutics. Further investigation into this novel therapy is warranted given the generally poor response of OCCC to our standard chemotherapy regimens. Experiments to investigate the efficacy of HO-3867 in OCCC in vivo are underway. Citation Format: Kristin L. Bixel, Uksha Saini, Jack Fowler, Sneja Rajendran, Ross Wanner, Noriomi Matsumura, Kalman Hideg, Ikuo Konishi, David Cohn, Selvendiran Karrupaiyah. Targeting STAT3 as a novel therapy for ovarian clear cell carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5405. doi:10.1158/1538-7445.AM2015-5405