Development of novel agents for ovarian cancer

Potential nanotechnologies and molecular targets in the quest for efficient chemotherapy in ovarian cancer

INTRODUCTION

Ovarian cancer, considered one of the most fatal gynecological cancers, goes largely undiagnosed until metastasis presents itself, usually once the patient is in the final stages and thus, too late for worthwhile therapy. Targeting this elusive disease in its early stages would improve the outcome for most patients, while the information generated thereof would increase the possibility of preventative mechanisms of therapy.

AREAS COVERED

This review discusses various molecular targets as possible moieties to be incorporated in a holistic drug delivery system or the more aptly termed 'theranostic' system. These molecular targets can be used for targeting, visualizing, diagnosing, and ultimately, treating ovarian cancer in its entirety. Currently implemented nanoframeworks, such as nanomicelles and nanoliposomes, are described and the effectiveness of nanostructures in tumor targeting, treatment functions, and overcoming the drug resistance challenge is discussed.

EXPERT OPINION

Novel nanotechnology strategies such as the development of nanoframeworks decorated with targeted ligands of a molecular nature may provide an efficient chemotherapy, especially when instituted in combination with imaging, diagnostic, and ultimately, therapeutic moieties. An imperative aspect of utilizing nanotechnology in the treatment of ovarian cancer is the flexibility of the drug delivery system and its ability to overcome standard obstacles such as: i) successfully treating the desired cells through direct targeting; ii) reducing toxicity levels of treatment by achieving direct targeting; and iii) delivery of targeted therapy using an efficient vehicle that is exceptionally degradable in response to a particular stimulus. The targeting of ovarian cancer in its early stages using imaging and diagnostic nanotechnology is an area that can be improved upon by combining therapeutic moieties with molecular biomarkers. The nanotechnology and molecular markers mentioned in this review have generally been used for either imaging or diagnostics, and have not yet been successfully implemented into bi-functional tools, which it is hoped, should eventually include a therapeutic aspect.

Hematopoietic cytokines as tumor markers in gynecological malignancies. A multivariate analysis in epithelial ovarian cancer patients

We investigated plasma levels of selected hematopoietic cytokines: stem cell factor (SCF), granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), and macrophage colony-stimulating factor (M-CSF) and the tumor marker cancer antigen (CA 125) in epithelial ovarian cancer patients as compared with control groups: benign ovarian tumor patients (cysts) and healthy subjects. Cytokine levels were determined by enzyme-linked immunosorbent assay, CA 125 - using the chemiluminescent microparticle immunoassay method. Our results have demonstrated significant differences in the concentrations of M-CSF, G-CSF, SCF (with the exception of GM-CSF), and CA 125 between the groups of ovarian cancer patients, cysts patients, and the healthy controls. When compared with CA 125, M-CSF has equal or higher values of diagnostic sensitivity and specificity. The M-CSF area under the receiver-operating characteristic curve (AUC) was the largest from all the cytokines tested and slightly lower than the AUC of CA 125. These findings suggest the usefulness of M-CSF in diagnosing ovarian cancer, especially when discriminating between cancer and non-carcinoma lesions.

Prognostic impact of concomitant p53 and PTEN on outcome in early stage (FIGO I-II) epithelial ovarian cancer

INTRODUCTION

The objective of the study was to evaluate the prognostic effect of p53, PTEN, and concomitant p53 PTEN status on clinicopathologic features, recurrent disease, and disease-free survival (DFS) of 131 patients in FIGO stages I to II with epithelial ovarian cancer.

METHODS

The technique of tissue microarray and immunohistochemistry was used for the detection of positivity of the biologic markers p53 and PTEN.

RESULTS

In the complete series, the 5-year DFS rate was 68%, and the overall survival rate was 71%. Positive staining for p53 and PTEN was detected in 25% and 22% of cases, respectively. Positivity of p53 was associated with tumor grade in the total series but not in the subgroup of serous tumors. In survival analysis, there was worse survival (P = 0.003) in the group of patients with p53-positive tumors compared with the group of patients with p53-negative tumors with DFS of 62% and 82%, respectively. Furthermore, DFS was 15% for the subgroup of patients with concomitant p53-positivity and PTEN-negativity of tumors compared with DFS of 62% for others in 1 group (p53+PTEN+, p53-PTEN+, p53-PTEN-) at 100 months. The difference was highly significant (P = 0.006). FIGO stage (odds ratio = 8.0) and p53 PTEN status (odds ratio = 0.6) were predictive factors for tumor recurrences in a logistic regression and prognostic factors with hazard ratios (HRs) of 4.0 and 0.6, respectively, in a multivariate Cox regression analysis. In a separate Cox regression analysis, FIGO stage (HR = 3.6) and p53 status (HR = 2.0) were prognostic factors for DFS. For serous tumors (n = 51) recurrent disease was associated with FIGO stage (P = 0.013), and p53 loss (P = 0.029) but not with FIGO grade (P = 0.169).

CONCLUSIONS

p53 status divides ovarian carcinomas into 2 subgroups after prognosis, also in serous tumors. Presence of PTEN in p53-positive tumors seems to protect from bad prognosis and absence of PTEN seems to worsen prognosis in early stages.

Prognostic impact of p53, p27, and C-MYC on clinicopathological features and outcome in early-stage (FIGO I-II) epithelial ovarian cancer

INTRODUCTION

The objective of the study was to evaluate the prognostic effect of p53, p27, and C-MYC on clinicopathological features, recurrent disease, and disease-free survival (DFS) of 131 patients with ovarian cancer in International Federation of Gynecology and Obstetrics (FIGO) stages I-II.

METHODS

The technique of tissue microarray and immunohistochemistry was used for detection of positivity/overexpression of the biological markers p53, p27, and C-MYC.

RESULTS

In the complete series, the 5-year and overall survival rates were 68% and 71%, respectively. Positive staining for p53, p27, and C-MYC was detected in 25%, 57%, and 76% of cases, respectively. Positivity of p53, p27, concomitant p53-p27, C-MYC, and C-MYC-p27 status were associated with tumor grade. Positivity of p27 and concomitant p53-p27 were related to serous tumors. In survival analysis, DFS was related to p53, combined p53-p27, and combined p53-C-MYC status. Significant predictive factors for tumor recurrences were the FIGO stage (odds ratio [OR] = 9.8), status of node sampling (OR = 0.2), and p53 status (OR = 3.7) in a logistic regression analysis. In a multivariate Cox regression analysis, FIGO stage (hazard ratio [HR] = 4.3) and p53 status (HR = 3.0) were significant prognostic factors for DFS. In a separate Cox regression analysis, FIGO stage (HR = 2.0) and concomitant p53-p27-C-MYC status (HR = 0.3) were independent prognostic factors for DFS. It was possible to identify a subgroup, constituting 30% of the patients, who had excellent survival with tumors of concomitant p53 negativity, p27 positivity, and C-MYC positivity apart from the clinicopathological factors. Patients in this subgroup were longtime survivors with DFS of 92% at 5 and 9 years.

CONCLUSIONS

The results of this study strongly suggest that patients with p53-positive tumors (alone/or combined with p27 and/or C-MYC) had significantly worse survival (DFS) compared with patients with p53-negative tumors. Patients with p53-positive tumors continued to have recurrences after the 5-year follow-up and die in disease.