Margaret Whicker

Efficacy and Safety of Higher Dose Stereotactic Radiosurgery for Functional Pituitary Adenomas: A Preliminary Report

OBJECTIVE Single fraction stereotactic radiosurgery (SRS) is a common adjuvant therapy for hormonally active pituitary adenomas when surgical resection fails to control tumor growth or normalize hypersecretory activity. Marginal doses of 20-24 Gy are used at many centers and here we report our outcome data in patients treated with a higher marginal dose of 35 Gy. METHODS Thirty-one patients with secretory pituitary adenomas (adrenocorticotropic hormone, n = 15; growth hormone, n = 13; prolactin, n = 2; thyroid-stimulating hormone, n = 1) were treated with 35 Gy to the 50% isodose line, and had a mean follow-up time of 40.2 months (range = 12-96). All patients were evaluated post-SRS for time to hormonal normalization, time to relapse, as well as incidence and time course of radiation-induced hypopituitarism and cranial neuropathies. RESULTS Initial normalization of hypersecretion was achieved in 22 patients (70%) with a median time to remission of 17.7 months. After initial hormonal remission, 7 patients (32%) experienced an endocrine relapse, with a mean time to relapse of 21 months. New endocrine deficiency within any of the five major hormonal axes occurred in 10 patients (32%). One patient (3%) developed new-onset unilateral optic nerve pallor within the temporal field 3 years after SRS. Three patients (10%) reported transient new or increasing frontal headaches of unclear etiology following their procedures. CONCLUSION Time to endocrine remission was more rapid in patients treated with 35 Gy, as compared to previously reported literature using marginal doses of 20-24 Gy. Rates of endocrine remission and relapse, post-SRS hypopituitarism, and radiation-induced sequelae were not increased following higher dose treatment.

Triapine Disrupts CtIP-mediated Homologous Recombination Repair and Sensitizes Ovarian Cancer Cells to PARP and Topoisomerase Inhibitors

PARP inhibitors exploit synthetic lethality to target epithelial ovarian cancer (EOC) with hereditary BRCA mutations and defects in homologous recombination repair (HRR). However, such an approach is limited to a small subset of EOC patients and compromised by restored HRR due to secondary mutations in BRCA genes. Here, it was demonstrated that triapine, a small-molecule inhibitor of ribonucleotide reductase, enhances the sensitivity of BRCA wild-type EOC cells to the PARP inhibitor olaparib and the topoisomerase II inhibitor etoposide. Triapine abolishes olaparib-induced BRCA1 and Rad51 foci, and disrupts the BRCA1 interaction with the Mre11–Rad50–Nbs1 (MRN) complex in BRCA1 wild-type EOC cells. It has been shown that phosphorylation of CtIP (RBBP8) is required for the interaction with BRCA1 and with MRN to promote DNA double-strand break (DSB) resection during S and G2 phases of the cell cycle. Mechanistic studies within reveal that triapine inhibits cyclin-dependent kinase (CDK) activity and blocks olaparib-induced CtIP phosphorylation through Chk1 activation. Furthermore, triapine abrogates etoposide-induced CtIP phosphorylation and DSB resection as evidenced by marked attenuation of RPA32 phosphorylation. Concurrently, triapine obliterates etoposide-induced BRCA1 foci and sensitizes BRCA1 wild-type EOC cells to etoposide. Using a GFP-based HRR assay, it was determined that triapine suppresses HRR activity induced by an I-SceI–generated DSB. These results suggest that triapine augments the sensitivity of BRCA wild-type EOC cells to drug-induced DSBs by disrupting CtIP-mediated HRR. Implications: These findings provide a strong rationale for combining triapine with PARP or topoisomerase inhibitors to target HRR-proficient EOC cells. Mol Cancer Res; 12(3); 381–93. ©2014 AACR.

Triapine potentiates platinum-based combination therapy by disruption of homologous recombination repair

Background:Platinum resistance may be attributable to inherent or acquired proficiency in homologous recombination repair (HRR) in epithelial ovarian cancer (EOC). The objective of this study was to evaluate the efficacy of the small molecule inhibitor triapine to disrupt HRR and sensitise BRCA wild-type EOC cells to platinum-based combination therapy in vitro and in vivo.Methods:The sensitivity of BRCA wild-type cancer cells to olaparib, cisplatin, carboplatin, doxorubicin, or etoposide in combination with triapine was evaluated by clonogenic survival assays. The effects of triapine on HRR activity in cells were measured with a DR-GFP reporter assay. The ability of triapine to enhance the effects of the carboplatin-doxil combination on EOC tumour growth delay was determined using a xenograft tumour mouse model.Results:Platinum resistance is associated with wild-type BRCA status. Triapine inhibits HRR activity and enhances the sensitivity of BRCA wild-type cancer cells to cisplatin, olaparib, and doxorubicin. However, sequential combination of triapine and cisplatin is necessary to achieve synergism. Moreover, triapine potentiates platinum-based combination therapy against BRCA wild-type EOC cells and produces significant delay of EOC tumour growth.Conclusions:Triapine promises to augment the clinical efficacy of platinum-based combination regimens for treatment of platinum-resistant EOC with wild-type BRCA and proficient HRR activity.

MK-2206 sensitizes BRCA-deficient epithelial ovarian adenocarcinoma to cisplatin and olaparib

BackgroundPlatinum resistance is a major obstacle in the treatment of epithelial ovarian cancer (EOC). Activation of the AKT pathway promotes platinum resistance while inhibition of AKT sensitizes chemoresistant cells. Patients with BRCA mutant EOC, and thus a defect in the homologous recombination (HR) repair pathway, demonstrate greater clinical response to platinum and olaparib therapy than patients with BRCA wild-type EOC. MK-2206, an allosteric inhibitor of AKT phosphorylation, sensitizes a variety of cell types to various anticancer agents and is currently undergoing phase II trials as monotherapy for platinum-resistant ovarian, fallopian tube, and peritoneal cancer. This study examines the differential effects of AKT inhibition with cisplatin and olaparib therapy in BRCA1/2-deficient versus wild-type EOC.MethodsPEO1, a chemosensitive BRCA2-mutant serous ovarian adenocarcinoma, and PEO4, a reverted BRCA2-proficient line from the same patient after the development of chemotherapeutic resistance, were primarily used for the study. In PEO1, MK-2206 demonstrated moderate to strong synergism with cisplatin and olaparib at all doses, while demonstrating antagonism at all doses in PEO4.ResultsBaseline phospho-AKT activity in untreated cells was upregulated in both BRCA1- and 2-deficient cell lines. MK-2206 prevented cisplatin- and olaparib-induced AKT activation in the BRCA2-deficient PEO1 cells. We propose that BRCA-deficient EOC cells upregulate baseline AKT activity to enhance survival in the absence of HR. Higher AKT activity is also required to withstand cytotoxic agent-induced DNA damage, leading to strong synergism between MK-2206 and cisplatin or olaparib therapy in BRCA-deficient cells.ConclusionsMK-2206 shows promise as a chemosensitization agent in BRCA-deficient EOC and merits clinical investigation in this patient population.

Management of sexuality, intimacy, and menopause symptoms in patients with ovarian cancer

&NA; Issues of sexuality, intimacy, and early menopause significantly impact the quality of life of patients following the diagnosis and treatment of ovarian cancer. These are undertreated problems. Successful treatment requires the providers awareness of the problem, ability to identify it, and willingness to treat it. Unfortunately many providers do not address these issues in the pretreatment or perioperative period. Furthermore, patients do not often alert their providers to their symptoms. While systemic hormone therapy may improve many of the issues, they are not appropriate for all patients given their action on estrogen receptors. However, other nonhormonal treatments exist including selective serotonin reuptake inhibitors, antiepileptics, natural remedies, and pelvic floor physical therapy. In addition psychological care and the involvement of the partner can be helpful in managing the sexual health concerns of these patients. At the time of diagnosis or at initial consultation, women should be informed of the potential physiologic, hormonal, and psychosocial effects of ovarian cancer on sexuality and that there is a multimodal approach to dealing with symptoms.

Associated characteristics and impact on recurrence and survival of free-floating tumor fragments in the lumen of fallopian tubes in Type I and Type II endometrial cancer

Objective This study sought to evaluate characteristics of cases of free-floating tumor fragments within the lumen of fallopian tubes (‘floaters’) on final pathology for Type I and Type II endometrial adenocarcinoma, including relationships with disease recurrence and mortality. Methods A single institution experience of 1022 consecutive cases of uterine cancer presenting between 2005 and 2010 was retrospectively reviewed, with data extraction from electronic medical records. Associations of floaters with baseline characteristics were studied with logistic regression, and relationships with disease recurrence and survival were assessed with Cox proportional hazards models. Results Among 816 included cases of Type I or Type II endometrial adenocarcinoma, floaters were identified on final pathology for 20 patients (2.5%). Patient characteristics of cases with floaters mirrored the overall sample. With adjustment, presence of floaters trended towards association with laparoscopic/robotic approach (OR = 3.84; 95%CI 0.98-15.1), and was significantly associated with lymphovascular invasion (OR = 9.65; 95%CI 2.35-39.6) and higher stage disease. Although floaters were associated with increased risk of recurrence in unadjusted analysis (HR = 3.22; 95%CI 1.41-7.37), after adjustment for disease type, stage, and patient comorbidities, no evidence for impact on disease recurrence or overall survival was found. Conclusions The presence of floaters is rare. Floaters were generally associated with more extensive disease, but no evidence was found to show any independent prognostic impact on risk of recurrence or death. In agreement with prior research, this study found a trend towards association of floaters with laparoscopic/robotic approach, indicating the possibility of floaters sometimes being the result of trauma from uterine manipulator insertion.

Abstract 4490: Triapine sensitizes chemoresistant ovarian cancer cells to platinum therapy.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Objectives: Epithelial ovarian cancer (EOC) is the second most common female pelvic reproductive organ cancer in the United States, and carries the highest mortality in this category in the Western world. The progression free survival and overall survival depend greatly on tumor sensitivity to a platinum chemotherapy. Once platinum resistance is encountered, response rates of only 6-30% are achieved. Triapine, a novel small-molecule drug developed in our laboratory, potently inhibits the activity of ribonucleotide reductase involved in the key step of DNA synthesis and replication. Given that triapine caused profound disruption of dNTP levels and S phase progression, we examined the effects of triapine on the repair of replication-associated DSBs and on the sensitivity of platinum resistant EOC to DNA damaging and platinum therapy. Methods: Cell sensitivity to varying ratios of treating drug combinations (triapine/6-thio-guanine alone, triapine/6-thioguanine with cisplatin, carboplatin, doxorubicin, or paclitaxel) was carried out by clonogenic survival assays using multiple EOC cells lines (A2780, CP70, CAOV-3, IGROV-1, BG-1, PEO1, PEO4, SKOV-3). Colonies were stained and counted to determine % survival. DNA replication was determined by EdU incorporation into DNA using flow cytometry and confocal microscopy. Results: Treatment with triapine leads to synergistic sensitization of BRCA wild-type EOC cells to platinum drugs. The degree of sensitization by triapine is more pronounced toward the lower concentrations of platinum drugs, at which DNA replication is still ongoing. Platinum drugs induce DNA double strand breaks (DSBs) and Rad51 foci in BRCA wild type EOC cells. Triapine attenuates formation of Rad51 foci, a marker of DSB repair, in these cells. For EOC cells that are highly platinum resistant, combination of triapine and 6-thioguanine is required to achieve significant sensitization to platinum drugs. Conclusions: Platinum drugs induce replication-associated DSBs and Rad51-dependent repair in BRCA wild-type EOC cells. Triapine inhibits Rad51-dependent repair of DSBs and therefore sensitizes BRCA wild-type EOC cells to platinum drugs. The mechanism by which 6-thioguanine enhances the effects of triapine is currently being investigated. Our findings indicate for the first time that triapine and 6-thioguanine can be used in combination with platinum agents to target BRCA wild-type and platinum-resistant EOC. Citation Format: Elena S. Ratner, Margaret Whicker, Z. Ping Lin, Alan C. Sartorelli. Triapine sensitizes chemoresistant ovarian cancer cells to platinum therapy. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4490. doi:10.1158/1538-7445.AM2013-4490

Abstract 3277: Pifithrin-α and veliparib synergize in the sensitization of p53 wild-type ovarian cells to cisplatin therapy.:

Objectives. Veliparib (ABT), a PARP1/2 inhibitor, has been studied in ovarian adenocarcinoma treatment, particularly in conjunction with platinum therapy, and sensitizes cells to cisplatin (Cis). Pifithrin-α (PFT), a transcriptional inhibitor of p53, sensitizes p53 wild-type ovarian cancer cells to antimicrotubule agent-induced apoptosis. No studies have evaluated the interaction of PFT with platinum drugs or PARP inhibitors. We evaluated the potential synergistic interactions between PFT and ABT/Cis in p53 intact ovarian cancer cells. Methods. We conducted clonogenic assays using BG-1, a human ovarian adenocarcinoma cell line with WT p53 activity. Cells were seeded in 6-well plates and, after 24 hours, treated with combinations of 5μM PFT and multiple doses of ABT and Cis. After 8 days, colony counts were obtained with automated GelDoc software. To identify synergistic interactions, Combination Indices (CI) were calculated with Calcusyn software. Results. At the lowest dose of Cis (0.625μM), relative cell survival is 60.4% with Cis-PFT, 64.9% with Cis-ABT, and 24.5% with Cis-ABT-PFT. At the highest dose (10μM), relative cell survival is 34.3% with Cis-PFT, 5.25% with Cis-ABT, and 0.85% with Cis-ABT-PFT. At low concentrations of Cis, Cis-PFT showed mild to moderate antagonism. At Cis concentrations >2.5μM, moderate synergism developed. At all concentrations, PFT-ABT showed moderate to strong antagonism. Cis-ABT-PFT showed moderate to strong synergism at all concentrations. Conclusions. PFT sensitizes BG-1 cells to Cis in a dose dependent pattern, improving synergism at increasing doses of both Cis and PFT. In contrast, PFT shows marked antagonism to the cytotoxic effects of ABT, independent of ABT dose. The combination of ABT+PFT shows strong, dose-independent synergism in the sensitization of BG-1 cells to Cis and significantly reduces relative survival, suggesting the potential for improved tumor control at reduced doses of cisplatin in p53 WT ovarian cancer. Citation Format: Margaret Whicker, Brian Liang, Z. Ping Lin, Alan Sartorelli, Elena Ratner. Pifithrin-α and veliparib synergize in the sensitization of p53 wild-type ovarian cells to cisplatin therapy. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3277. doi:10.1158/1538-7445.AM2013-3277