Tumor heterogeneity in ovarian cancer as demonstrated by in vitro chemoresistance assays

Gynecologic and Breast Cancers: What's New in Chemoresistance and Chemosensitivity Tests?

Gynecological and breast cancers affect women's health worldwide. Although chemotherapy is one of the principal treatments for cancer, it also has limitations owing to toxicity and tumor resistance to the drugs used. Thus, individualized treatment based on personal tumor characteristics is essential for improving therapeutic outcomes and patient survival. Chemoresistance and chemosensitivity tests can be useful for predicting tumor response and guiding chemotherapy choices. This methodology has already been applied to breast, ovarian, cervical, and endometrial cancers, identifying successfully which drugs cause resistance and sensitivity responses for each individual person, influencing their progression-free survival and overall response. In addition, more recent techniques, such as organoids and patient-derived xenografts, can also recapitulate patients' tumor characteristics and contribute to chemo response evaluation. Therefore, this review compiles information on chemoresistance and chemosensitivity tests performed in gynecologic and breast cancers and their main results for women's health improvement.

Estrogen-related receptor alpha copy number variation is associated with ovarian cancer histological grade

AIM

Copy number variations (CNVs) are related to the genetic and phenotypic diversity of cancers and identifying genetic alterations could improve treatment strategies. Here, we used The Cancer Genome Atlas (TCGA) to explore associations between estrogen-related receptor alpha (ESRRA) CNVs and histological grade in patients with ovarian cancer (OC).

METHODS

Gene expression data and clinical information of 620 OC patients were obtained from The Cancer Genome Atlas）TCGA and associations between ESRRA CNVs and clinical characteristics were evaluated. Multivariate logistic regression analyses to obtain odds ratios (ORs) using a 95% confidence interval (CI) were performed, adjusting for race, age, histological grade, and tumor size.

RESULTS

ESRRA CNVs were associated with histological grade (OR 0.6235 [95% CI, 0.3593-0.8877]; p < 0.05) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PPARGC1A) CNVs (OR -0.6298 [95% CI, -0.9011 to -0.3585]; p < 0.05). In multivariate analyses, ESRRA CNVs remained significantly associated with histological grade (OR 0.6492 [95% CI, 0.3549-0.9435]; p < 0.05) and PPARGC1A CNVs (OR -0.6236 [95% CI, -0.9269 to 0.3203]; p < 0.05).

CONCLUSION

There was a significant association between ESRRA CNVs in patients with OC and histological grade of the cancer.

Genome-wide DNA copy number analysis in clonally expanded human ovarian cancer cells with distinct invasive/migratory capacities

Ovarian cancer has the worst prognosis of any gynecological malignancy, and generally presents with metastasis at advanced stages. Copy number variation (CNV) frequently contributes to the alteration of oncogenic drivers. In this study, we sought to identify genetic targets in heterogeneous clones from human ovarian cancers cells. We used array-based technology to systematically assess all the genes with CNVs in cell models clonally expanded from A2780 and SKOV3 ovarian cancer cell lines with distinct highly and minimally invasive/migratory capacities. We found that copy number alterations differed between matched highly and minimally invasive/migratory subclones, differentially affecting specific functional processes including immune response processes, DNA damage repair, cell cycle and cell proliferation. We also identified seven genes as strong candidates, including DDB1, ERCC1, ERCC2, PRPF19, BCAT1, CDKN1B and MARK4, by integrating the above data with gene expression and clinical outcome data. Thus, by determining the molecular signatures of heterogeneous invasive/migratory ovarian cancer cells, we identified genes that could be specifically targeted for the treatment and prognosis of advanced ovarian cancers.

Personalized in vitro cancer models to predict therapeutic response: Challenges and a framework for improvement

Personalized cancer therapy focuses on characterizing the relevant phenotypes of the patient, as well as the patient's tumor, to predict the most effective cancer therapy. Historically, these methods have not proven predictive in regards to predicting therapeutic response. Emerging culture platforms are designed to better recapitulate the in vivo environment, thus, there is renewed interest in integrating patient samples into in vitro cancer models to assess therapeutic response. Successful examples of translating in vitro response to clinical relevance are limited due to issues with patient sample acquisition, variability and culture. We will review traditional and emerging in vitro models for personalized medicine, focusing on the technologies, microenvironmental components, and readouts utilized. We will then offer our perspective on how to apply a framework derived from toxicology and ecology towards designing improved personalized in vitro models of cancer. The framework serves as a tool for identifying optimal readouts and culture conditions, thus maximizing the information gained from each patient sample.

The PI3K/AKT/mTOR pathway is a potential predictor of distinct invasive and migratory capacities in human ovarian cancer cell lines

Objectives

To explore the genetic and molecular events that control subclones exhibiting distinct invasive/migratory capacities derived from human epithelial ovarian cancer (EOC) cell line A2780 and SKOV3.

Methods

Single-cell subclones were isolated and established that were derived from the SKOV3 and A2780 cell lines through limiting dilution methodology. Transwell insert assays and MTT assays were performed to screen and identify the subclones exhibiting the highest and the lowest invasive/migratory capacities, and the selected subclones were renamed as A-H (A2780 high), A-L (A2780 low), S-H (SKOV3 high), and S-L (SKOV3 low). Their biological characteristics were evaluated. RNA-Seq was conducted on the targeted subclones.

Results

Compared with their corresponding counterparts, A-H/S-H cells exhibited significantly higher invasive/migratory capacities (P < 0.001 and = 0.001, respectively). A-H/S-H cells displayed a clear reduction in doubling time (P = 0.004 and 0.001, respectively), and a significant increase in the percentage of cells in S phase (P = 0.004 and 0.022, respectively). Additionally, the apoptotic rates of A-H/S-H cells were significantly lower than those of A-L/S-L cells (P = 0.002 and 0.026, respectively). At both mRNA and protein levels, caspase-3 and caspase-7 expression were reduced but Bcl-2 expression was increased in A-H/S-H cells. The TrkB (anoikis-related) and Beclin1 (autophagy-related) levels were consistently high and low, respectively, in both A-H/S-H cells. Resistance to chemotherapy in vitro and higher capacities on tumor formation in vivo was presented in both A-H/S-H cells. PI3K/AKT/mTOR pathway components, PIK3CA, PIK3CD, AKT3, ECM1, GPCR, mTOR and PRKCB were increased but that the Nur77 and PTEN were decreased in A-H/S-H cells, identified by RNA-Seq and consistently confirmed by RT-PCR and Western blot analyses.

Conclusions

Heterogeneous cell subpopulations exhibiting distinct invasive and migratory capacities co-exist within the SKOV3 and A2780 cell lines. PI3K/AKT/mTOR pathway activation is associated with higher invasive and migratory capacities in subpopulations of human ovarian cancer cell lines. Inhibiting this pathway may be useful for the chemoprevention or treatment of EOC.

In vitro chemoresponse in metachronous pairs of gyneclologic cancers

Background

While most gynecologic cancers respond to first-line cytotoxic chemotherapy, treatment of recurrent disease is frequently associated with acquired drug resistance. In order to find an in vitro surrogate of this clinical phenomenon, a tumor chemoresponse assay was studied.

Methods/Materials

Patients who had tissue submitted for repeated chemoresponse testing were identified through a retrospective search. Sixty-three patients met inclusion criteria (chemoresponse testing completed at primary diagnosis and upon recurrence of disease and assays completed ≥90 days apart). The Wilcoxon signed-rank test was used to compare chemoresponse, represented as a response index (RI), between primary and recurrent measurements. In a secondary analysis, response was categorized and coded as Responsive = 3, Intermediately Responsive = 2 and Non-Responsive = 1, and the paired t-test was used to compare chemoresponse between primary and recurrent measurement.

Results

Median time between primary and recurrent tumor testing was 309 days (IQR 208–422). Drugs tested included carboplatin, cisplatin, docetaxel, doxorubicin, gemcitabine, paclitaxel, topotecan, and combination carboplatin/gemcitabine and carboplatin/paclitaxel. There were no differences in chemoresponse between primary and recurrent measurement when chemoresponse was represented by RI scores; although a trend toward increased resistance to paclitaxel upon recurrence was noted. When chemoresponse was analyzed as a continuous variable corresponding to categorized response, a significant shift toward increased resistance to paclitaxel at recurrence, and a marginally significant trend toward increased resistance to carboplatin at recurrence, were observed.

Conclusions

We observed a trend toward increased chemoresistance at recurrence for paclitaxel, and a marginally significant trend toward increased chemoresistance to carboplatin, but no change in chemoresponsiveness between primary diagnosis and recurrence of disease for other common chemotherapy drugs, including common second-line agents such as doxorubicin, gemcitabine, and topotecan.

Harnessing the potential of lipid-based nanomedicines for type-specific ovarian cancer treatments

Epithelial ovarian cancers are a group of at least five histologically and clinically distinct diseases, yet at this time patients with these different diseases are all treated with the same platinum and taxane-based chemotherapeutic regimen. With increased knowledge of histotype-specific differences that correlate with treatment responses and resistance, novel treatment strategies will be developed for each distinct disease. Type-specific or resistance-driven molecularly targeted agents will provide some specificity over traditional chemotherapies and it is argued here that nanoscaled drug delivery systems, in particular lipid-based formulations, have the potential to improve the delivery and specificity of pathway-specific drugs and broad-spectrum cytotoxic chemotherapeutics. An overview of the current understanding of ovarian cancers and the evolving clinical management of these diseases is provided. This overview is needed as it provides the context for understanding the current role of drug delivery systems in the treatment of ovarian cancer and the need to design formulations for treatment of clinically distinct forms of ovarian cancer.

Chemotherapeutic drug sensitivity of primary cultures of epithelial ovarian cancer cells from patients in relation to tumour characteristics and therapeutic outcome

BACKGROUND

A number of chemotherapeutic drugs are active in epithelial ovarian cancer (EOC) but so far choice of drugs for treatment is mostly empirically based. Testing of drug activity in tumour cells from patients might provide a rationale for a more individualised approach for drug selection.

MATERIAL AND METHODS

Sensitivity of EOC to chemotherapeutic drugs was analysed in 125 tumour samples from 112 patients using a short-term primary culture assay based on the concept of total cell kill. Sensitivity was related to tumour histology, treatment status and clinical tumour response.

RESULTS

For most EOC standard drugs serous high grade and clear cell EOC were the most sensitive subtypes and the mucinous tumours the most resistant subtype. Docetaxel, however, tended to show the opposite pattern. Samples from previously treated patients tended to be more resistant than those from treatment naïve patients. The activity of cisplatin correlated with that of other drugs with the exception of docetaxel. Tumour samples from two sites in the same patient at the same occasion showed similar cisplatin sensitivity in contrast to samples taken at different occasions. Samples from patients responding in the clinic to treatment were more sensitive to most drugs than samples from non-responding patients. At the individual patient level, drug sensitivity in vitro compared with clinical response showed sensitivities and specificities in the 83-100% and 55-83% ranges, respectively.

CONCLUSIONS

Assessment of EOC tumour cell drug sensitivity in vitro provides clinically relevant and potentially useful information for the optimisation of drug treatment.

Predicting platinum resistance in primary advanced ovarian cancer patients with an in vitro resistance index

PURPOSE

We aimed to identify primary platinum resistance in epithelial ovarian cancer (OC) patients with FIGO stage III-IV disease by an in vitro drug-response assay and to correlate the findings with clinical response. We considered whether neoadjuvant chemotherapy or anatomic sample site and tumor heterogeneity would influence the results.

METHODS

We combined the ATP-based tumor-chemosensitivity and the extreme drug resistance assays for testing of 85 biopsies from 58 patients. Tumors were classified as sensitive or resistant by a resistance index (RI). We did separate analyses of primary tumors and metastases and compared chemo-naïve samples with samples obtained after neoadjuvant chemotherapy. Results were analyzed for association with clinical platinum resistance, progression-free survival (PFS), and overall survival (OS).

RESULTS

RI · 250 predicted primary platinum resistance, without misclassification of sensitive patients. The test sensitivity for primary tumors was 15/15, specificity 3/10, negative predictive value 3/3, and positive predictive value 15/22. Patients with in vitro platinum-resistant samples had shorter PFS compared with patients with sensitive samples (3.4 vs. 10.0 months, p = 0.02). Comparing patient-matched primary and metastatic samples, there was about 1/3 mismatch in resistance. RI for platinum was lower in primary tumors exposed to neoadjuvant chemotherapy than in chemo-naïve tumors (p < 0.01).

CONCLUSIONS

This in vitro assay predicted primary platinum resistance, without misclassification of sensitive OC patients, and the results were significantly associated with PFS. We suggest that samples from primary tumor and metastatic samples have different responses to chemotherapy and that exposure to chemotherapy might induce in vitro platinum resistance.

Sensor-based cell and tissue screening for personalized cancer chemotherapy

Personalized tumor chemotherapy depends on reliable assay methods, either based on molecular "predictive biomarkers" or on a direct, functional ex vivo assessment of cellular chemosensitivity. As a member of the latter category, a novel high-content platform is described monitoring human mamma carcinoma explants in real time and label-free before, during and after an ex vivo modeled chemotherapy. Tissue explants are sliced with a vibratome and laid into the microreaction chambers of a 24-well sensor test plate. Within these ~23 μl volume chambers, sensors for pH and dissolved oxygen record rates of cellular oxygen uptake and extracellular acidification. Robot-controlled fluid system and incubation are parts of the tissue culture maintenance system while an integrated microscope is used for process surveillance. Sliced surgical explants from breast cancerous tissue generate well-detectable ex vivo metabolic activity. Metabolic rates, in particular oxygen consumption rates have a tendency to decrease over time. Nonetheless, the impact of added drugs (doxorubicin, chloroacetaldehyde) is discriminable. Sensor-based platforms should be evaluated in explorative clinical studies for their suitability to support targeted systemic cancer therapy. Throughput is sufficient for testing various drugs in a range of concentrations while the information content obtained from multiparametric real-time analysis is superior to conventional endpoint assays.

Combination of CA125 and RECAF biomarkers for early detection of ovarian cancer

Ovarian cancer can be cured in up to 90% of cases if diagnosed early. CA125, the most studied ovarian cancer biomarker, exhibits poor sensitivity for detecting early disease stages and low specificity to malignancy. RECAF, the alpha-fetoprotein receptor, is a wide-spectrum oncofetal antigen with clinical potential for cancer diagnosis, screening, and monitoring. This study evaluated the performance of RECAF as a diagnostic tool and the sensitivity of a combination of RECAF and CA125 to detect early stages of ovarian cancer at a cutoff resulting in 100% specificity among healthy women. This retrospective case–control study was designed to measure the serum levels of RECAF and CA125 in normal individuals (n = 106) and cancer patients stages I/II (RECAF, n = 32; CA125, n = 35) and III/IV (RECAF, n = 49; CA125, n = 51). A competitive chemiluminescence assay was developed to measure the circulating RECAF. To eliminate any false positives, we classified as positive any patient with a RECAF or a CA125 value higher than their respective 100% specificity cutoff. We have shown that RECAF discriminated cancer and healthy donors better than CA125, particularly in the early stages (AUC_RECAF = 0.96 and AUC_CA125 = 0.805). CA125 sensitivity was lower in the early stages than in the advance stages; RECAF sensitivity was high at all stages. A combination of CA125 and RECAF detected three out of four early-stage patients, with no false positives. In conclusion, the combination of RECAF and CA125 serum values provides the specificity and the sensitivity necessary to screen for ovarian cancer and in particular, to detect early stages of the disease.

Heterogeneity in primary tumors and corresponding metastases: could it provide us with any hints to personalize cancer therapy?

Interpatient variability in response to anticancer drugs is associated with different clinical outcomes, which is partially owing to the individual differences among patients. Many investigators have hoped that tumor heterogeneity would help to reveal the underlying mechanism of interpatient variability in response to anticancer therapy. Numerous studies have demonstrated the presence of intratumor heterogeneity and the heterogeneity in primary tumors and corresponding metastases in a wide range of tumors at different levels and have indicated that the heterogeneity might make sense as a potential determinant of anticancer therapy response. This article discusses tumor heterogeneity, focusing on the heterogeneity in primary tumors and corresponding metastases as well as the effect on anticancer therapy response. Furthermore, an idea of tumor-site-based personalized cancer therapy for patients with metastatic malignancies was hypothesized, and a strategy using a patient-derived tumor tissue xenograft model to realize this idea is also proposed in this article.

Prevalence of in vitro chemotherapeutic drug resistance in primary malignant pleural mesothelioma: result in a cohort of 203 resection specimens

OBJECTIVE

Optimizing the multimodality treatment of malignant pleural mesothelioma depends on many factors including an adequate chemotherapeutic response. Currently, chemotherapy regimens for patients with mesothelioma are empirically selected. In vitro chemotherapy resistance in human mesothelioma has not been reported. Our goal was to determine the prevalence of drug resistance in a large sample of malignant pleural mesothelioma using a commercially available assay.

METHODS

Tumors specimens (n = 203) were cultured for analysis of chemoresistance using the extreme drug resistance assay. Evaluable results were obtained in 168 (168/203 = 83%) specimens. Each specimen was tested with 3 drugs: cisplatin, gemcitabine, and vinorelbine. Drug resistance was characterized as low, intermediate, or extreme. Median age was 64 years (30-85 years). Forty-four (26%) patients received neoadjuvant chemotherapy before sampling and testing. The distribution of histopathologic cell types was epithelial (103; 61%), mixed (57; 34%), and sarcomatoid (8; 5%).

RESULTS

A significant proportion of tumors had extreme/intermediate drug resistance to cisplatin (27%), gemcitabine (31%), or vinorelbine (59%). Nineteen tumors (11%) had extreme/intermediate resistance to all 3 drugs. Resistance (extreme/intermediate) to cisplatin was more prevalent in epithelial tumors than in nonepithelial (33% vs 18%; P = .0394). No significant differences in chemoresistance were found in tumors of patients who had received neoadjuvant chemotherapy compared with those who had not.

CONCLUSIONS

The feasibility of performing off-site in vitro drug resistance assays on resected malignant mesothelioma specimens is reported. A significant proportion of mesothelioma tumors exhibited extreme/intermediate resistance to cisplatin, gemcitabine, or vinorelbine.

Genomic analysis of genetic heterogeneity and evolution in high-grade serous ovarian carcinoma

Resistance to chemotherapy in ovarian cancer is poorly understood. Evolutionary models of cancer predict that, following treatment, resistance emerges either because of outgrowth of an intrinsically resistant sub-clone or evolves in residual disease under the selective pressure of treatment. To investigate genetic evolution in high-grade serous (HGS) ovarian cancers, we first analysed cell line series derived from three cases of HGS carcinoma before and after platinum resistance had developed (PEO1, PEO4 and PEO6; PEA1 and PEA2; and PEO14 and PEO23). Analysis with 24-colour fluorescence in situ hybridisation and single nucleotide polymorphism (SNP) array comparative genomic hybridisation (CGH) showed mutually exclusive endoreduplication and loss of heterozygosity events in clones present at different time points in the same individual. This implies that platinum-sensitive and -resistant disease was not linearly related, but shared a common ancestor at an early stage of tumour development. Array CGH analysis of six paired pre- and post-neoadjuvant treatment HGS samples from the CTCR-OV01 clinical study did not show extensive copy number differences, suggesting that one clone was strongly dominant at presentation. These data show that cisplatin resistance in HGS carcinoma develops from pre-existing minor clones but that enrichment for these clones is not apparent during short-term chemotherapy treatment.

Clinical relevance of extent of extreme drug resistance in epithelial ovarian carcinoma

OBJECTIVE

The objective of this study was to evaluate the clinical significance of the extent of extreme drug resistance (EDR) in in vitro drug resistance assays in advanced epithelial ovarian, fallopian, and primary peritoneal cancers.

METHODS

A retrospective study was conducted using the database for in vitro drug resistance assay (EDR Assay, Oncotech, Inc.) results for advanced stage ovarian cancer samples obtained at primary surgery between 1995 and 2009. In vitro drug resistance assay results were evaluated for thirteen drugs according to the following two groups: platinum and taxane (primary treatment group) vs remaining agents (secondary treatment group). Dual-resistance was then defined as at least one EDR in the primary and secondary treatment groups. Chemotherapy response and survival outcome were correlated with assay results.

RESULTS

There were 253 cases identified. Dual-resistance (n=53, 20.9%) was not associated with chemotherapy response (p=0.62) or survival outcomes (PFS, p=0.52; OS, p=0.11). Only one (0.4%) case exhibited complete EDR to all tested drugs, and 74 (29.4%) cases showed no EDR. There was no statistical correlation between total number of drugs in the EDR range and chemotherapy response (p=0.55), progression-free survival (PFS) (p=0.18), and overall survival (OS) (p=0.87). Proportion of EDR, defined as the ratio of the number of EDR drugs divided by all drugs for an individual patient, was also not related to chemotherapy response (p=0.37), PFS (p=0.13), or OS (p=0.13).

CONCLUSIONS

Presence of extreme drug resistance to multiple agents in the in vitro drug resistance assays was not associated with survival outcomes in advanced stage epithelial ovarian, fallopian, and primary peritoneal cancers.

Extreme drug resistance assay results do not influence survival in women with epithelial ovarian cancer

OBJECTIVES

Extreme drug resistance (EDR) assays have been used to identify chemotherapy regimens that are least likely to be of clinical benefit in the treatment of epithelial ovarian cancer (EOC). We sought to examine the impact of EDR assay-guided therapy on the outcome of patients with EOC in the primary and recurrent settings.

METHODS

We conducted a retrospective review of demographic, pathologic, EDR assay and clinical outcome data from 377 patients with EOC who had an assay sent at the time of their primary or subsequent cytoreductive surgeries. Multivariate analyses were performed using Cox proportional hazards method to identify and estimate the impact of independent prognostic factors on time to progression (TTP), overall survival (OS) and survival after recurrence (RS).

RESULTS

Increasing age was associated with a worse OS and RS (HR=1.34; 95% CI, 1.14-1.58 and HR=1.14; 95% CI, 1.00-1.31, respectively for each decade increase in age). Surgical outcome in the setting of primary or secondary cytoreduction remained an important predictor of survival. Compared with patients with microscopic residual disease, patients who were left with 0.1 to 1.0 cm and >1.0 cm residual disease had an increased risk of recurrence (HR=1.94; 95% CI, 1.33 to 2.84 and HR=3.61; 95% CI; 2.07 to 6.39, respectively) and death (HR=1.59; 95% CI, 1.03 to 2.45; and HR=2.14; 95% CI, 1.09 to 4.20, respectively). For patients who recurred, those who did not undergo secondary cytoreductive surgery and patients who were left with >1.0 cm residual had an increased risk of death compared to patients with microscopic residual (HR=2.13; 95% CI, 1.28 to 3.54; and HR=2.84; 95% CI, 1.71 to 4.71, respectively). EDR assay results analyzed for single agents or combinations of chemotherapies failed to independently predict patient outcomes no matter if the assay was performed at the time of the primary surgery or recurrence.

CONCLUSION

EDR assay results do not independently predict or alter the outcomes of patients with EOC who are treated with the current standards of primary cytoreductive surgery followed by platinum and taxane combination chemotherapy.

In vitro extreme drug resistance assay to taxanes or platinum compounds for the prediction of clinical outcomes in epithelial ovarian cancer: a prospective cohort study

PURPOSE

We sought to investigate the efficacy of in vitro extreme drug resistance (EDR) assay for the prediction of drug response, platinum-resistance (progression-free survival, PFS <6 months) and survival in patients with epithelial ovarian cancer (EOC) who received taxane- and platinum-based chemotherapy after surgery.

METHODS

Between December 2005 and August 2007, 43 patients were enrolled prospectively. They underwent staging laparotomy followed by six or nine cycles of taxane- and platinum-based chemotherapy, and their tumors were submitted for in vitro EDR assay to taxanes (paclitaxel or docetaxel) and platinum compounds (carboplatin or cisplatin).

RESULTS

The rates of EDR to taxanes and platinum compounds were 20.9% (9/43) and 23.3% (10/43). Patients with EDR to platinum compounds showed a lower rate of overall response (60 vs. 100%), a higher rate of platinum-resistance (50 vs. 18.2%) and poor overall survival (OS) (median OS; 29.2 vs. 33.7 months) than those without EDR to platinum compounds (P < 0.05), whereas patients with EDR to taxanes showed poor PFS than those without EDR to taxanes (12.5 vs. 19 months, P < 0.01). Moreover, suboptimal debulking surgery and EDR to taxanes were poor prognostic factors for PFS (adjusted hazard ratio 3.215 and 3.984; 95% confidence interval 1.845-7.895 and 3.814-11.674, respectively) although there was no independent risk factor for poor OS by the multivariate Cox's proportional hazard analysis.

CONCLUSIONS

In vitro EDR assay to taxanes and platinum compounds may be helpful for predicting drug response, platinum-resistance and survival in patients with EOC who received taxane- and platinum-based chemotherapy after staging laparotomy.