A novel cell line panel reveals non-genetic mediators of platinum resistance and phenotypic diversity in high grade serous ovarian cancer.

OBJECTIVES: Resistance to cancer therapy is an enduring challenge and accurate and reliable preclinical models are lacking. We interrogated this unmet need using high grade serous ovarian cancer (HGSC) as a disease model. METHODS: We created five in vitro and two in vivo platinum-resistant HGSC models and characterised the entire cell panel via whole genome sequencing, RNASeq and creation of intraperitoneal models. RESULTS: Mutational signature analysis indicated that platinum-resistant cell lines evolved from a pre-existing ancestral clone but a unifying mutational cause for drug resistance was not identified. However, cisplatin-resistant and carboplatin-resistant cells evolved recurrent changes in gene expression that significantly overlapped with independent samples obtained from multiple patients with relapsed HGSC. Gene Ontology Biological Pathways (GOBP) related to the tumour microenvironment, particularly the extracellular matrix, were repeatedly enriched in cisplatin-resistant cells, carboplatin-resistant cells and also in human resistant/refractory samples. The majority of significantly over-represented GOBP however, evolved uniquely in either cisplatin- or carboplatin-resistant cell lines resulting in diverse intraperitoneal behaviours that reflect different clinical manifestations of relapsed human HGSC. CONCLUSIONS: Our clinically relevant and usable models reveal a key role for non-genetic factors in the evolution of chemotherapy resistance. Biological pathways relevant to the extracellular matrix were repeatedly expressed by resistant cancer cells in multiple settings. This suggests that recurrent gene expression changes provide a fitness advantage during platinum therapy and also that cancer cell-intrinsic mechanisms influence the tumour microenvironment during the evolution of drug resistance. Candidate genes and pathways identified here could reveal therapeutic opportunities in platinum-resistant HGSC.

Correction: Safety and utility of image-guided research biopsies in relapsed high-grade serous ovarian carcinoma-experience of the BriTROC consortium.

This article was originally published under a CC BY NC SA License, but has now been made available under a CC BY 4.0 License.

Safety and utility of image-guided research biopsies in relapsed high-grade serous ovarian carcinoma-experience of the BriTROC consortium.

BACKGROUND: Investigating tumour evolution and acquired chemotherapy resistance requires analysis of sequential tumour material. We describe the feasibility of obtaining research biopsies in women with relapsed ovarian high-grade serous carcinoma (HGSC). METHODS: Women with relapsed ovarian HGSC underwent either image-guided biopsy or intra-operative biopsy during secondary debulking, and samples were fixed in methanol-based fixative. Tagged-amplicon sequencing was performed on biopsy DNA. RESULTS: We screened 519 patients in order to enrol 220. Two hundred and two patients underwent successful biopsy, 118 of which were image-guided. There were 22 study-related adverse events (AE) in the image-guided biopsies, all grades 1 and 2; pain was the commonest AE. There were pre-specified significant AE in 3/118 biopsies (2.5%). 87% biopsies were fit-for-purpose for genomic analyses. Median DNA yield was 2.87 µg, and was higher in biopsies utilising 14 G or 16 G needles compared to 18 G. TP53 mutations were identified in 94.4% patients. CONCLUSIONS: Obtaining tumour biopsies for research in relapsed HGSC is safe and feasible. Adverse events are rare. The large majority of biopsies yield sufficient DNA for genomic analyses-we recommend use of larger gauge needles and methanol fixation for such biopsies, as DNA yields are higher but with no increase in AEs.

Extracellular matrix educates an immunoregulatory tumor macrophage phenotype found in ovarian cancer metastasis.

Recent studies have shown that the tumor extracellular matrix (ECM) associates with immunosuppression, and that targeting the ECM can improve immune infiltration and responsiveness to immunotherapy. A question that remains unresolved is whether the ECM directly educates the immune phenotypes seen in tumors. Here, we identify a tumor-associated macrophage (TAM) population associated with poor prognosis, interruption of the cancer immunity cycle, and tumor ECM composition. To investigate whether the ECM was capable of generating this TAM phenotype, we developed a decellularized tissue model that retains the native ECM architecture and composition. Macrophages cultured on decellularized ovarian metastasis shared transcriptional profiles with the TAMs found in human tissue. ECM-educated macrophages have a tissue-remodeling and immunoregulatory phenotype, inducing altered T cell marker expression and proliferation. We conclude that the tumor ECM directly educates this macrophage population found in cancer tissues. Therefore, current and emerging cancer therapies that target the tumor ECM may be tailored to improve macrophage phenotype and their downstream regulation of immunity.

A multicentre retrospective cohort study of ovarian germ cell tumours: Evidence for chemotherapy de-escalation and alignment of paediatric and adult practice.

BACKGROUND: Adult guidelines recommend BEP (bleomycin, etoposide, cisplatin) for all ovarian germ cell tumours, causing debilitating toxicities in young patients who will survive long term. Paediatricians successfully reduce toxicities by using lower bleomycin doses and substituting carboplatin for cisplatin, while testicular and paediatric immature teratomas (ITs) are safely managed with surgery alone. AIM: The aim was to determine whether reduced-toxicity treatment could rationally be extended to patients older than 18 years. METHODS: Multicentre cohort study was carried out in four large UK cancer centres over 12 years. RESULTS: One hundred thirty-eight patients were enrolled. Overall survival was 93%, and event-free survival (EFS) was 72%. Neoadjuvant/adjuvant chemotherapy (82% BEP) caused 27 potentially chronic toxicities, and one patient subsequently died from acute lymphoblastic leukaemia. There was no difference in histology, stage or grade in patients ≤/>18 years, and EFS was not different in these age groups (≤18:28% and >18:28%; log-rank P = 0.96). Histological subtype powerfully predicted EFS (log-rank P = 4.9 × 10-7). Neoadjuvant/adjuvant chemotherapy reduced future relapse/progression in dysgerminoma (n = 37, chemo:0% vs. no chemo:20%), yolk sac tumour (n = 23, 26.3% vs.75%) and mixed germ cell tumour (n = 32, 40%vs.70%) but not in IT (n = 42, 33% vs.15%). Additionally, we observed no radiological responses to chemotherapy in ITs, pathological IT grade did not predict EFS (univariate hazard ratio 0.82, 95% confidence interval: 0.57-1.19, P = 0.94) and there were no deaths in this subtype. CONCLUSION: Survival was excellent but chemotherapy toxicities were severe, implying significant overtreatment. Our data support the extension of reduced-toxicity, paediatric regimens to adults. Our practice-changing findings that IT was chemotherapy resistant and pathological grade uninformative strongly endorse exclusive surgical management of ovarian ITs at all ages.

Pharmacokinetics and tissue penetration of temocillin.

The pharmacokinetics of intravenous (bolus) temocillin 1 g were studied in 6 healthy male volunteers, and a cantharides blister method was used to estimate tissue penetration of the antibiotic. The mean elimination half-life was 4.5 hours. Temocillin penetrated blister fluid rapidly and reached concentrations of about 50% of those in serum by 2 to 3 hours after administration. Over an 8-hour period, the serum and blister fluid concentrations exceeded the MIC90 of susceptible bacteria by 2-fold or greater, suggesting that twice or even once daily dosing with temocillin may be sufficient.

A prospective survey of hospital cross-infection with Streptococcus pneumoniae.

A prospective survey of pneumococcal carriage and infection between October 1984 and April 1985 in a male medical ward of a district general hospital is reported. In the hospital as a whole, pneumococcal infection, acquired more than 5 days after admission, accounted for some 20% of all pneumococcal infection.

Oncolytic adenoviral mutants induce a novel mode of programmed cell death in ovarian cancer.

Oncolytic adenoviral mutants have considerable activity in ovarian cancer. However, the mechanisms by which they induce cell death remain uncertain. dl922-947, which contains a 24 bp deletion in E1A CR2, is more potent than both E1A wild-type adenoviruses and the E1B-55K deletion mutant dl1520 (Onyx-015). We investigated the mode of death induced by three E1A CR2-deleted replicating adenoviruses in models of ovarian cancer and also the importance of E3 11.6 (adenovirus death protein) in determining this mode of death. Ovarian cancer cells were infected with dl922-947 (E3 11.6+) and dlCR2 (E3 11.6-). We also generated dlCR2 tSmac, which also encodes the gene for processed Smac/DIABLO. Classical apoptosis does not occur in adenoviral cell death and there is no role for mitochondria. Expression of Smac/DIABLO does not enhance cytotoxicity nor increase apoptotic features. A role for cathepsins and lysosomal membrane permeability was excluded. Autophagy is induced, but is not the mode of death and may act as a cell survival mechanism. There is no evidence of pure necrosis, while the presence of E3 11.6 does not modulate the mode or extent of cell death. Thus, E1A CR2-deleted oncolytic adenoviral cytotoxicity in ovarian cancer may define a novel mode of programmed cell death.

Survivin interacts with Smac/DIABLO in ovarian carcinoma cells but is redundant in Smac-mediated apoptosis.

Abnormalities in the control and execution of apoptosis are seen in many malignancies, including ovarian carcinoma. Many of these abnormalities involve the mitochondrial pathway of apoptosis, including overexpression of BIR-containing inhibitor of apoptosis protein (IAP) family proteins as well as dysregulated apoptosome function. We sought to stimulate the mitochondrial pathway of apoptosis by constructing a recombinant adenovirus encoding mature, processed Smac/DIABLO (Ad CMV tSmac), the second mitochondrial activator of caspases. Transfection of ovarian carcinoma cells with Ad CMV tSmac leads to increasing apoptosis in a dose-dependent manner. By contrast, transfection of IOSE397 immortalized normal ovarian surface epithelial cells does not cause apoptosis. We also show that the processed form of Smac is primarily expressed in the cytosol of ovarian carcinoma cells. Smac co-immunoprecipitates with both survivin and XIAP and stimulates survivin, but not XIAP, down-regulation. This down-regulation does not result from transcriptional changes, as determined by quantitative real-time PCR, but cycloheximide treatment indicates that survivin half-life is reduced from 6 to 2 h, which is secondary to ubiquitination and proteasomal degradation. RNA interference, however, suggests that survivin does not act to inhibit Smac-mediated apoptosis, which is confirmed by cotransfection with the phosphorylation mutant, survivin T34A. Finally, intraperitoneal delivery of Ad CMV tSmac increases median survival of mice bearing human ovarian carcinoma xenografts. We believe that expression of Smac/DIABLO can stimulate the intrinsic pathway of apoptosis in ovarian carcinoma without damaging normal ovarian tissue and therefore has therapeutic potential.

The pharmacokinetics of ofloxacin and a review of its tissue penetration.

The pharmacokinetics of ofloxacin were studied in six healthy volunteers following a 600 mg oral dose. The concentration of the compound was measured in serum, inflammatory fluid and urine. Ofloxacin was rapidly absorbed, the mean maximum concentration of ofloxacin being 10.7 mg/l at 1.2 h. The mean serum elimination half-life was 7 h and 80.3% of the administered compound was recovered in the urine by 48 h. Ofloxacin penetrated the inflammatory fluid well, the mean peak level being 5.2 mg/l at 5.3 h. A review of the tissue penetration is presented which indicates that the high volume of distribution of ofloxacin is associated with good tissue penetration.

The pharmacokinetics and tissue penetration of ofloxacin.

The pharmacokinetics of the 4-quinolone agent, ofloxacin, were studied in six healthy volunteers, following a 600 mg oral dose. The levels of the compound were measured by a microbiological assay in serum, blister fluid and urine. The compound was rapidly absorbed, the mean maximum concentration of ofloxacin being 10.7 mg/l at 1.2 h. The mean serum elimination half-life was 7 h and 80.3% of the administered compound was recovered in the urine by 48 h. Ofloxacin penetrated the blister fluid well, the mean peak level being 5.2 mg/l at 5.3 h.

The pharmacokinetics and tissue penetration of imipenem.

Two studies were performed to investigate the penetration of imipenem into chemically induced inflammatory exudate and into peritoneal fluid. In the first study six volunteers received 500 mg of imipenem, alone and with 500 mg cilastatin. Little difference was noted in the pharmacokinetics or inflammatory fluid penetration of imipenem when given with or without cilastatin. The only significant alteration was the urine recovery (an increase from a mean of 14.7% to 55.6% in the presence of the enzyme inhibitor). The mean inflammatory fluid level of imipenem at 30 min was 6.2 mg/l (or 35% of the plasma level). The inflammatory fluid levels exceeded the plasma levels after 2 h. The overall penetration of imipenem/cilastatin into inflammatory fluid was 67.8% (+/- 13.8) and imipenem alone 73.2% (+/- 13.9). The mean elimination half-life of imipenem from plasma was 1.1 h and from inflammatory fluid 1.4 h (with or without cilastatin). In the second study, 29 patients received 1 g imipenem plus cilastatin before elective surgery and plasma and peritoneal levels were measured over 4 h. There was considerable penetration of the peritoneum, imipenem levels in excess of 30 mg/l being found 15 min after administration declining to 5-7 mg/l by 3-4 h. The mean percentage penetration was 73.4% (+/- 22.1). A brief review of the literature on imipenem tissue penetration is included.