Sir Peter MacCallum Department of Oncology - Research Publications

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Author: Au-Yeung, George × Author: Bowtell, David × Author: Mileshkin, Linda ×

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    Small-scale mutations are infrequent as mechanisms of resistance in post-PARP inhibitor tumour samples in high grade serous ovarian cancer
    Burdett, NL ; Willis, MO ; Pandey, A ; Fereday, S ; DeFazio, A ; Bowtell, DDL ; Christie, EL (NATURE PORTFOLIO, 2023-12-10)
    While the introduction of poly-(ADP)-ribose polymerase (PARP) inhibitors in homologous recombination DNA repair (HR) deficient high grade serous ovarian, fallopian tube and primary peritoneal cancers (HGSC) has improved patient survival, resistance to PARP inhibitors frequently occurs. Preclinical and translational studies have identified multiple mechanisms of resistance; here we examined tumour samples collected from 26 women following treatment with PARP inhibitors as part of standard of care or their enrolment in clinical trials. Twenty-one had a germline or somatic BRCA1/2 mutation. We performed targeted sequencing of 63 genes involved in DNA repair processes or implicated in ovarian cancer resistance. We found that just three individuals had a small-scale mutation as a definitive resistance mechanism detected, having reversion mutations, while six had potential mechanisms of resistance detected, with alterations related to BRCA1 function and mutations in SHLD2. This study indicates that mutations in genes related to DNA repair are detected in a minority of HGSC patients as genetic mechanisms of resistance. Future research into resistance in HGSC should focus on copy number, transcriptional and epigenetic aberrations, and the contribution of the tumour microenvironment.
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    Multiomic analysis of homologous recombination-deficient end-stage high-grade serous ovarian cancer
    Burdett, NL ; Willis, MO ; Alsop, K ; Hunt, AL ; Pandey, A ; Hamilton, PT ; Abulez, T ; Liu, X ; Hoang, T ; Craig, S ; Fereday, S ; Hendley, J ; Garsed, DW ; Milne, K ; Kalaria, S ; Marshall, A ; Hood, BL ; Wilson, KN ; Conrads, KA ; Pishas, K ; Ananda, S ; Scott, CL ; Antill, Y ; McNally, O ; Mileshkin, L ; Hamilton, A ; Au-Yeung, G ; Devereux, L ; Thorne, H ; Bild, A ; Bateman, NW ; Maxwell, GL ; Chang, JT ; Conrads, TPP ; Nelson, BH ; Bowtell, DDL ; Christie, ELL (NATURE PORTFOLIO, 2023-03)
    High-grade serous ovarian cancer (HGSC) is frequently characterized by homologous recombination (HR) DNA repair deficiency and, while most such tumors are sensitive to initial treatment, acquired resistance is common. We undertook a multiomics approach to interrogate molecular diversity in end-stage disease, using multiple autopsy samples collected from 15 women with HR-deficient HGSC. Patients had polyclonal disease, and several resistance mechanisms were identified within most patients, including reversion mutations and HR restoration by other means. We also observed frequent whole-genome duplication and global changes in immune composition with evidence of immune escape. This analysis highlights diverse evolutionary changes within HGSC that evade therapy and ultimately overwhelm individual patients.
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    CCNE1 Amplification as a Therapeutic Target
    Au-Yeung, G ; Mileshkin, L ; Bowtell, DDL (LIPPINCOTT WILLIAMS & WILKINS, 2023-03-20)
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    Endometriosis and menopausal hormone therapy impact the hysterectomy-ovarian cancer association.
    Khoja, L ; Weber, RP ; Australian Ovarian Cancer Study Group, ; Webb, PM ; Jordan, SJ ; Muthukumar, A ; Chang-Claude, J ; Fortner, RT ; Jensen, A ; Kjaer, SK ; Risch, H ; Doherty, JA ; Harris, HR ; Goodman, MT ; Modugno, F ; Moysich, K ; Berchuck, A ; Schildkraut, JM ; Cramer, D ; Terry, KL ; Anton-Culver, H ; Ziogas, A ; Phung, MT ; Hanley, GE ; Wu, AH ; Mukherjee, B ; McLean, K ; Cho, K ; Pike, MC ; Pearce, CL ; Lee, AW (Elsevier BV, 2022-01)
    OBJECTIVE: To evaluate the association between hysterectomy and ovarian cancer, and to understand how hormone therapy (HT) use and endometriosis affect this association. METHODS: We conducted a pooled analysis of self-reported data from 11 case-control studies in the Ovarian Cancer Association Consortium (OCAC). Women with (n = 5350) and without ovarian cancer (n = 7544) who never used HT or exclusively used either estrogen-only therapy (ET) or estrogen+progestin therapy (EPT) were included. Risk of invasive epithelial ovarian cancer adjusted for duration of ET and EPT use and stratified on history of endometriosis was determined using odds ratios (ORs) with 95% confidence intervals (CIs). RESULTS: Overall and among women without endometriosis, there was a positive association between ovarian cancer risk and hysterectomy (OR = 1.19, 95% CI 1.09-1.31 and OR = 1.20, 95% CI 1.09-1.32, respectively), but no association upon adjusting for duration of ET and EPT use (OR = 1.04, 95% CI 0.94-1.16 and OR = 1.06, 95% CI 0.95-1.18, respectively). Among women with a history of endometriosis, there was a slight inverse association between hysterectomy and ovarian cancer risk (OR = 0.93, 95% CI 0.69-1.26), but this association became stronger and statistically significant after adjusting for duration of ET and EPT use (OR = 0.69, 95% CI 0.48-0.99). CONCLUSIONS: The hysterectomy-ovarian cancer association is complex and cannot be understood without considering duration of ET and EPT use and history of endometriosis. Failure to take these exposures into account in prior studies casts doubt on their conclusions. Overall, hysterectomy is not risk-reducing for ovarian cancer, however the inverse association among women with endometriosis warrants further investigation.
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    Resistance to CDK2 Inhibitors Is Associated with Selection of Polyploid Cells in CCNE1-Amplified Ovarian Cancer
    Etemadmoghadam, D ; Au-Yeung, G ; Wall, M ; Mitchell, C ; Kansara, M ; Loehrer, E ; Batzios, C ; George, J ; Ftouni, S ; Weir, BA ; Carter, S ; Gresshoff, I ; Mileshkin, L ; Rischin, D ; Hahn, WC ; Waring, PM ; Getz, G ; Cullinane, C ; Campbell, LJ ; Bowtell, DD (AMER ASSOC CANCER RESEARCH, 2013-11-01)
    PURPOSE: Amplification of cyclin E1 (CCNE1) is associated with poor outcome in breast, lung, and other solid cancers, and is the most prominent structural variant associated with primary treatment failure in high-grade serous ovarian cancer (HGSC). We have previously shown that CCNE1-amplified tumors show amplicon-dependent sensitivity to CCNE1 suppression. Here, we explore targeting CDK2 as a novel therapeutic strategy in CCNE1-amplified cancers and mechanisms of resistance. EXPERIMENTAL DESIGN: We examined the effect of CDK2 suppression using RNA interference and small-molecule inhibitors in SK-OV-3, OVCAR-4, and OVCAR-3 ovarian cancer cell lines. To identify mechanisms of resistance, we derived multiple, independent resistant sublines of OVCAR-3 to CDK2 inhibitors. Resistant cells were extensively characterized by gene expression and copy number analysis, fluorescence-activated cell sorting profiling and conventional karyotyping. In addition, we explored the relationship between CCNE1 amplification and polyploidy using data from primary tumors. RESULTS: We validate CDK2 as a therapeutic target in CCNE1-amplified cells by showing selective sensitivity to suppression, either by gene knockdown or using small-molecule inhibitors. In addition, we identified two resistance mechanisms, one involving upregulation of CDK2 and another novel mechanism involving selection of polyploid cells from the pretreatment tumor population. Our analysis of genomic data shows that polyploidy is a feature of cancer genomes with CCNE1 amplification. CONCLUSIONS: These findings suggest that cyclinE1/CDK2 is an important therapeutic target in HGSC, but that resistance to CDK2 inhibitors may emerge due to upregulation of CDK2 target protein and through preexisting cellular polyploidy.