Panobinostat enhances olaparib efficacy by modifying expression of homologous recombination repair and immune transcripts in ovarian cancer

Histone deacetylase inhibitors (HDACi) sensitize homologous recombination (HR)-proficient human ovarian cancer cells to PARP inhibitors (PARPi). To investigate mechanisms of anti-tumor effects of combined HDACi/PARPi treatment we performed transcriptome analysis in HR- proficient human ovarian cancer cells and tested drug effects in established immunocompetent mouse ovarian cancer models. Human SKOV-3 cells were treated with vehicle (Con), olaparib (Ola), panobinostat (Pano) or Pano+Ola and RNA-seq analysis performed. DESeq2 identified differentially expressed HR repair and immune transcripts. Luciferised syngeneic mouse ovarian cancer cells (ID8-luc) were treated with the HDACi panobinostat alone or combined with olaparib and effects on cell viability, apoptosis, DNA damage and HR efficiency determined. C57BL/6 mice with intraperitoneally injected ID8-luc cells were treated with panobinostat and/or olaparib followed by assessment of tumor burden, markers of cell proliferation, apoptosis and DNA damage, tumor-infiltrating T cells and macrophages, and other immune cell populations in ascites fluid. There was a significant reduction in expression of 20/37 HR pathway genes by Pano+Ola, with immune and inflammatory-related pathways also significantly enriched by the combination. In ID8 cells, Pano+Ola decreased cell viability, HR repair, and enhanced DNA damage. Pano+Ola also co-operatively reduced tumor burden and proliferation, increased tumor apoptosis and DNA damage, enhanced infiltration of CD8+ T cells into tumors, and decreased expression of M2-like macrophage markers. In conclusion, panobinostat in combination with olaparib targets ovarian tumors through both direct cytotoxic and indirect immune-modulating effects

Stimulating TAM-mediated anti-tumor immunity with mannose-decorated nanoparticles in ovarian cancer

BACKGROUND: Current cancer immunotherapies have made tremendous impacts but generally lack high response rates, especially in ovarian cancer. New therapies are needed to provide increased benefits. One understudied approach is to target the large population of immunosuppressive tumor-associated macrophages (TAMs). Using inducible transgenic mice, we recently reported that upregulating nuclear factor-kappaB (NF-κB) signaling in TAMs promotes the M1, anti-tumor phenotype and limits ovarian cancer progression. We also developed a mannose-decorated polymeric nanoparticle system (MnNPs) to preferentially deliver siRNA payloads to M2, pro-tumor macrophages in vitro. In this study, we tested a translational strategy to repolarize ovarian TAMs via MnNPs loaded with siRNA targeting the inhibitor of NF-κB alpha (IκBα) using mouse models of ovarian cancer. METHODS: We evaluated treatment with MnNPs loaded with IκBα siRNA (IκBα-MnNPs) or scrambled siRNA in syngeneic ovarian cancer models. ID8 tumors in C57Bl/6 mice were used to evaluate consecutive-day treatment of late-stage disease while TBR5 tumors in FVB mice were used to evaluate repetitive treatments in a faster-developing disease model. MnNPs were evaluated for biodistribution and therapeutic efficacy in both models. RESULTS: Stimulation of NF-κB activity and repolarization to an M1 phenotype via IκBα-MnNP treatment was confirmed using cultured luciferase-reporter macrophages. Delivery of MnNPs with fluorescent payloads (Cy5-MnNPs) to macrophages in the solid tumors and ascites was confirmed in both tumor models. A three consecutive-day treatment of IκBα-MnNPs in the ID8 model validated a shift towards M1 macrophage polarization in vivo. A clear therapeutic effect was observed with biweekly treatments over 2-3 weeks in the TBR5 model where significantly reduced tumor burden was accompanied by changes in immune cell composition, indicative of reduced immunosuppressive tumor microenvironment. No evidence of toxicity associated with MnNP treatment was observed in either model. CONCLUSIONS: In mouse models of ovarian cancer, MnNPs were preferentially associated with macrophages in ascites fluid and solid tumors. Evidence of macrophage repolarization, increased inflammatory cues, and reduced tumor burden in IκBα-MnNP-treated mice indicate beneficial outcomes in models of established disease. We have provided evidence of a targeted, TAM-directed approach to increase anti-tumor immunity in ovarian cancer with strong translational potential for future clinical studies

Chromosome 3 Anomalies Investigated by Genome Wide SNP Analysis of Benign, Low Malignant Potential and Low Grade Ovarian Serous Tumours

Ovarian carcinomas exhibit extensive heterogeneity, and their etiology remains unknown. Histological and genetic evidence has led to the proposal that low grade ovarian serous carcinomas (LGOSC) have a different etiology than high grade carcinomas (HGOSC), arising from serous tumours of low malignant potential (LMP). Common regions of chromosome (chr) 3 loss have been observed in all types of serous ovarian tumours, including benign, suggesting that these regions contain genes important in the development of all ovarian serous carcinomas. A high-density genome-wide genotyping bead array technology, which assayed >600,000 markers, was applied to a panel of serous benign and LMP tumours and a small set of LGOSC, to characterize somatic events associated with the most indolent forms of ovarian disease. The genomic patterns inferred were related to TP53, KRAS and BRAF mutations. An increasing frequency of genomic anomalies was observed with pathology of disease: 3/22 (13.6%) benign cases, 40/53 (75.5%) LMP cases and 10/11 (90.9%) LGOSC cases. Low frequencies of chr3 anomalies occurred in all tumour types. Runs of homozygosity were most commonly observed on chr3, with the 3p12-p11 candidate tumour suppressor region the most frequently homozygous region in the genome. An LMP harboured a homozygous deletion on chr6 which created a GOPC-ROS1 fusion gene, previously reported as oncogenic in other cancer types. Somatic TP53, KRAS and BRAF mutations were not observed in benign tumours. KRAS-mutation positive LMP cases displayed significantly more chromosomal aberrations than BRAF-mutation positive or KRAS and BRAF mutation negative cases. Gain of 12p, which harbours the KRAS gene, was particularly evident. A pathology review reclassified all TP53-mutation positive LGOSC cases, some of which acquired a HGOSC status. Taken together, our results support the view that LGOSC could arise from serous benign and LMP tumours, but does not exclude the possibility that HGOSC may derive from LMP tumours

Ovarian cancer

Ovarian cancer is not a single disease and can be subdivided into at least five different histological subtypes that have different identifiable risk factors, cells of origin, molecular compositions, clinical features and treatments. Ovarian cancer is a global problem, is typically diagnosed at a late stage and has no effective screening strategy. Standard treatments for newly diagnosed cancer consist of cytoreductive surgery and platinum-based chemotherapy. In recurrent cancer, chemotherapy, anti-angiogenic agents and poly(ADP-ribose) polymerase inhibitors are used, and immunological therapies are currently being tested. High-grade serous carcinoma (HGSC) is the most commonly diagnosed form of ovarian cancer and at diagnosis is typically very responsive to platinum-based chemotherapy. However, in addition to the other histologies, HGSCs frequently relapse and become increasingly resistant to chemotherapy. Consequently, understanding the mechanisms underlying platinum resistance and finding ways to overcome them are active areas of study in ovarian cancer. Substantial progress has been made in identifying genes that are associated with a high risk of ovarian cancer (such as BRCA1 and BRCA2), as well as a precursor lesion of HGSC called serous tubal intraepithelial carcinoma, which holds promise for identifying individuals at high risk of developing the disease and for developing prevention strategies