Medical Biology - Research Publications
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ItemGalectin-7: A Novel Placental-released Driver of Preeclampsia.(SPRINGER HEIDELBERG, 2020-03-01)
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ItemTreatment and outcomes of unresectable and metastatic pancreatic cancer treated in public and private Australian hospitals(WILEY, 2021-11-23)BACKGROUND: Prior studies have reported for several cancer types that treatment in the private sector is associated with improved survival outcomes. Data for patients with locally advanced unresectable and metastatic pancreatic ductal adenocarcinoma (PDAC) have not previously been reported. METHODS: Analysis of patients from January 2016 to June 2020 registered to a multicentre prospective cancer database. Baseline demographic and clinicopathologic characteristics were compared. The Kaplan-Meier method was used to compare overall survival (OS). Multivariate Cox and logistic regression analyses were used to determine predictors of mortality and first-line chemotherapy treatment, respectively. RESULTS: Of 822 patients, 22.5% received private care. Private patients were older (median 71.5 vs. 68.9 years, p ≤ .05), had better performance status (ECOG 0 to 1: 82.2 vs. 73.5%, p = .05) and more likely to reside in an area with high socioeconomic advantage (67.0 vs. 19.6%, p ≤ .01). Private patients were more likely to receive first-line chemotherapy (69.7 vs. 54.2%, p ≤ .01) with logistic regression demonstrating private care (OR: 1.87, 95% CI: 1.20 to 2.97) as an independent predictor of receiving chemotherapy. Private patients had prolonged survival (median OS: 9.2 vs. 6.9 months, HR 1.2, p = .05). Receiving first-line chemotherapy was an independent predictor of mortality, but private care was not. CONCLUSIONS: Care in the private system is associated with improved OS, with higher uptake of first-line chemotherapy appearing to be the main contributor. Given the discrepancy, further studies are needed to determine what factors are driving this difference.
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ItemNo Preview AvailableInhibition of RNA polymerase I transcription activates targeted DNA damage response and enhances the efficacy of PARP inhibitors in high-grade serous ovarian cancer.(AMER ASSOC CANCER RESEARCH, 2020-07-01)Abstract Introduction: PARP inhibitors (PARPi) have revolutionized disease management of patients with homologous recombination (HR) DNA repair-deficient high-grade serous ovarian cancer (HGSOC). However, acquired resistance to PARPi is a major challenge in the clinic. The specific inhibitor of RNA polymerase I (Pol I) transcription of ribosomal RNA genes (rDNA) has demonstrated single-agent antitumor activity in p53 wild-type and p53-mutant hematologic malignancies (first-in-human trial, dose escalation study of CX-5461 at Peter MacCallum Cancer Centre) (Khot et al., Cancer Discov 2019). CX-5461 has also been reported to exhibit synthetic lethality with BRCA1/2 deficiency through stabilization of G-quadruplex DNA (GQ) structures. Here, we investigate the efficacy of CX-5461 in treating HGSOC. Experimental Design: The mechanisms by which CX-5461 induces DNA damage response (DDR) and displays synthetic lethality in HR-deficient HGSOC cells are explored. We present in vivo data of mice bearing two functionally and genomically profiled HGSOC-patient-derived xenograft (PDX)s treated with CX-5461 and olaparib, alone and in combination. We also investigate CX-5461-sensitivity gene expression signatures in primary and relapsed HGSOC. Results: Utilizing ovarian cancer cell lines, we demonstrate that sensitivity to CX-5461 is associated with “BRCA1 mutation” and “MYC targets” gene expression signatures. In addition, sensitivity to CX-5461 is associated with high basal rates of Pol I transcription. Importantly, we demonstrate a novel mechanism for CX-5461 synthetic lethal interaction with HR deficiency mediated through the induction of replication stress at rDNA repeats. Our data reveal CX-5461-mediated DDR in HR-deficient cells does not involve stabilization of GQ structures as previously proposed. On the contrary, we show definitively that CX-5461 inhibits Pol I recruitment leading to rDNA chromatin defects including stabilization of R-loops, single-stranded DNA, and replication stress at the rDNA. Mechanistically, we demonstrate CX-5461 leads to replication-dependent DNA damage involving MRE11-dependent degradation of replication forks. Importantly, CX-5461 has a different sensitivity spectrum to olaparib and cooperates with PARPi in exacerbating replication stress, leading to enhanced therapeutic efficacy in HR-deficient HGSOC-PDX in vivo compared to single-agent treatment of both drugs. Further, CX-5461 exhibits single-agent efficacy in olaparib-resistant HGSOC-PDX overcoming PARPi-resistance mechanisms involving fork protection. Importantly, we identify CX-5461-sensitivity gene expression signatures in primary and relapsed HGSOC. Conclusions: CX-5461 is a promising therapy alone and in combination therapy with PARPi in HR-deficient HGSOC. CX-5461 also has exciting potential as a treatment option for patients with relapsed HGSOC tumors that have high MYC activity and poor clinical outcome; these patients currently have very limited effective treatment options. This abstract is also being presented as Poster A71. Citation Format: Elaine Sanij, Katherine Hannan, Jiachen Xuan, Shunfei Yan, Jessica A. Ahern, Anna S. Trigos, Natalie Brajanovski, Jinbae Son, Keefe T. Chan, Olga Kondrashova, Elizabeth Lieschke, Matthew J. Wakefield, Sarah Ellis, Carleen Cullinane, Gretchen Poortinga, Kum Kum Khanna, Linda Mileshkin, Grant A. McArthur, John Soong, Els M. Berns, Ross D. Hannan, Clare L. Scott, Karen E. Sheppard, Richard B. Pearson. Inhibition of RNA polymerase I transcription activates targeted DNA damage response and enhances the efficacy of PARP inhibitors in high-grade serous ovarian cancer [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research; 2019 Sep 13-16, 2019; Atlanta, GA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(13_Suppl):Abstract nr PR13.