Objective Homologous recombination (HR) proficient ovarian cancers, including CCNE1 (cyclin E)-amplified tumors, are resistant to poly (ADP-ribose) polymerase inhibitors (PARPi). Histone deacetylase inhibitors (HDACi) are effective in overcoming tumor resistance to DNA damaging drugs. Our goal was to determine whether panobinostat, a newly FDA-approved HDACi, can sensitize cyclin E, HR-proficient ovarian cancer cells to the PARPi olaparib. Methods Expression levels of CCNE1 (cyclin E), BRCA1, RAD51 and E2F1 in ovarian tumors and cell lines were extracted from The Cancer Genome Atlas (TCGA) and Broad-Novartis Cancer Cell Line Encyclopedia (CCLE). In HR-proficient ovarian cancer cell line models (OVCAR-3, OVCAR-4, SKOV-3, and UWB1.289 + BRCA1 wild-type), cell growth and viability were assessed by sulforhodamine B and xenograft assays. DNA damage and repair (pH2AX and RAD51 co-localization and DRGFP reporter activity) and apoptosis (cleaved PARP and cleaved caspase-3) were assessed by immunofluorescence and Western blot assays. Results TCGA and CCLE data revealed positive correlations (Spearman) between cyclin E E2F1, and E2F1 gene targets related to DNA repair (BRCA1 and RAD51). Panobinostat downregulated cyclin E and HR repair pathway genes, and reduced HR efficiency in cyclin E-amplified OVCAR-3 cells. Further, panobinostat synergized with olaparib in reducing cell growth and viability in HR-proficient cells. Similar co-operative effects were observed in xenografts, and on pharmacodynamic markers of HR repair, DNA damage and apoptosis. Conclusions These results provide preclinical rationale for using HDACi to reduce HR in cyclin E-overexpressing and other types of HR-proficient ovarian cancer as a means of enhancing PARPi activity.

Key Points Question Did racial and ethnic minority adults with cancer in the United States experience more cancer care delays and adverse social and economic effects than White adults during the COVID-19 pandemic? Findings In this survey study of 1240 US adults with cancer, Black and Latinx adults reported experiencing higher rates of delayed cancer care and more adverse social and economic effects than White adults. Meaning This study suggests that the COVID-19 pandemic is associated with disparities in the receipt of timely cancer care among Black and Latinx adults.

Objective: Ovarian cancer is the second most common gynecological cancer and the number one cause of cancer death in gynecological cancers. In the United States alone, there are about 21,290 expected new cases in 2015 and about 14,180 expected deaths. Approximately 95% of ovarian malignancies are epithelial ovarian cancer (EOC). Most (50%) of these EOC tumors have BRCAness features - contain molecular defect in homologous recombination (HR) DNA repair pathways. About 20% of the non-BRACness subtypes of EOC exhibit increased expression of cyclin E (CCNE1) which is associated with resistance to DNA damaging drugs and increased mortality. A first-in-class drug, a poly(ADP-ribose) polymerase inhibitor (PARPi) olaparib was approved by the FDA for the treatment of advanced ovarian cancer patients with BRCA mutations who have had three or more lines chemotherapy. PARPi efficacy is lower in non-BRCAness tumors but may be enhanced by other drug combinations. Our group has shown that epigenetic histone deacetylase inhibitor (HDACi) therapy sensitizes ovarian cancer cells to various chemotherapeutic drugs. Our goal is to expand olaparib therapy to patients with chemoresistant tumors by sensitizing CCNE1 amplified EOC with the potent HDACi, panobinostat. Method: Ovarian cancer cell lines used were OVCAR-3 (CCNE1-amplified) and SKOV3 (CCNE1-non-amplified). They were co-treated with 0.01% DMSO vehicle, olaparib, panobinostat or olaparib/panobinostat combination. Sulforhodamine B (SRB) assays assessed cytotoxicity and immunofluorescence (IF) assessed markers of apoptosis (cleaved caspase-3). Images were analyzed using the Adobe Photoshop counting tool. Data analysis was performed via the Microsoft Excel average and percentage functions. Figures and p-value analysis were created using GraphPad Prism. Results: Our previous studies have demonstrated through western blot analysis of cleaved PARP expression that panobinostat enhances the pro-apoptotic effect of olaparib in CCNE1 amplified OVCAR-3 ovarian cancer cells. In this current study, IF was used to assess the established marker of apoptosis, cleaved caspase-3, in OVCAR3 and SKOV3 cells. Compared to vehicle-treated cells, olaparib alone induced no difference in the number of cleaved caspase-3 expression in both SKOV3 and OVCAR3 cells. However, there was significant upregulation in the percentage of cells positive for cleaved caspase-3 expression in combination treatments compared to single drug treatments in both cell lines. These data were supported by SRB cytotoxicity assays, where the combination of panobinostat and olaparib synergized in both OVCAR-3 and SKOV3 cells. Conclusion: The response of ovarian cancer cells to the PARPi olaparib is enhanced by co-treatment with HDACi panobinostat in vitro. This indicates that, responses to olaparib in HR-proficient EOC can be improved by combination therapy with panobinostat. Thus we have identified a novel way to expand the use of olaparib for the treatment of advanced ovarian cancer to patients with non-BRCA tumors. Note: This abstract was not presented at the conference. Citation Format: Kofi Sarfo-Kantanka, Andrew J. Wilson, Alexandra Steck, Jeanette Saskowski, Dineo Khabele. The histone deacetylase inhibitor panobinostat sensitizes cyclin E-amplified ovarian cancer cells to poly (ADP-ribose) polymerase inhibitor olaparib. [abstract]. In: Proceedings of the Eighth AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 13-16, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2016;25(3 Suppl):Abstract nr C79.

Objective: Ovarian cancer is the second most common gynecological cancer and the number one cause of cancer death in gynecological cancers. In the United States alone, there are about 21,290 expected new cases in 2015 and about 14,180 expected deaths. Approximately 95% of ovarian malignancies are epithelial ovarian cancer (EOC). Most (50%) of these EOC tumors have BRCAness features - contain molecular defect in homologous recombination (HR) DNA repair pathways. About 20% of the non-BRACness subtypes of EOC exhibit increased expression of cyclin E (CCNE1) which is associated with resistance to DNA damaging drugs and increased mortality. A first-in-class drug, a poly(ADP-ribose) polymerase inhibitor (PARPi) olaparib was approved by the FDA for the treatment of advanced ovarian cancer patients with BRCA mutations who have had three or more lines chemotherapy. PARPi efficacy is lower in non-BRCAness tumors but may be enhanced by other drug combinations. Our group has shown that epigenetic histone deacetylase inhibitor (HDACi) therapy sensitizes ovarian cancer cells to various chemotherapeutic drugs. Our goal is to expand olaparib therapy to patients with chemoresistant tumors by sensitizing CCNE1 amplified EOC with the potent HDACi, panobinostat. Method: Ovarian cancer cell lines used were OVCAR-3 (CCNE1-amplified) and SKOV3 (CCNE1-non-amplified). They were co-treated with 0.01% DMSO vehicle, olaparib, panobinostat or olaparib/panobinostat combination. Sulforhodamine B (SRB) assays assessed cytotoxicity and immunofluorescence (IF) assessed markers of apoptosis (cleaved caspase-3). Images were analyzed using the Adobe Photoshop counting tool. Data analysis was performed via the Microsoft Excel average and percentage functions. Figures and p-value analysis were created using GraphPad Prism. Results: Our previous studies have demonstrated through western blot analysis of cleaved PARP expression that panobinostat enhances the pro-apoptotic effect of olaparib in CCNE1 amplified OVCAR-3 ovarian cancer cells. In this current study, IF was used to assess the established marker of apoptosis, cleaved caspase-3, in OVCAR3 and SKOV3 cells. Compared to vehicle-treated cells, olaparib alone induced no difference in the number of cleaved caspase-3 expression in both SKOV3 and OVCAR3 cells. However, there was significant upregulation in the percentage of cells positive for cleaved caspase-3 expression in combination treatments compared to single drug treatments in both cell lines. Conclusion: The response of ovarian cancer cells to the PARPi olaparib is enhanced by co-treatment with HDACi panobinostat in vitro. This indicates that, responses to olaparib in HR-proficient EOC can be improved by combination therapy with panobinostat. Thus we have identified a novel way to expand the use of olaparib for the treatment of advanced ovarian cancer to patients with non-BRCA tumors. Citation Format: Kofi Sarfo-Kantanka, Andrew J. Wilson, Alexandra Steck, Jeanette Saskowski, Dineo Khabele. The histone deacetylase inhibitor panobinostat sensitizes cyclin E-amplified ovarian cancer cells to poly ADP-ribose polymerase inhibitor olaparib. [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 4730.