Abstract
Background/Aim: Many anticancer agents including molecularly-targeted drugs have been developed for ovarian cancer. However, the prognosis of recurrent ovarian cancer remains extremely poor. Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is reported as a rational target for ovarian cancer therapy. Moreover, serum HB-EGF expression is recognized as a biomarker in patients with primary ovarian cancer. Materials and Methods: We analysed serum samples with recurrent ovarian cancer at the Fukuoka University Hospital from April 2009 to March 2014. To assess the clinical significance of serum HB-EGF in recurrent ovarian cancer, the association between serum HB-EGF levels and prognosis in patients with recurrent ovarian cancer was examined using ELISA. Results: Patients with high serum HB-EGF expression showed a significantly poor response to second-line chemotherapeutic agents compared with patients with low HB-EGF levels. Conclusion: HB-EGF expression in serum may be a potential therapeutic indicator for novel HB-EGF-targeted therapy in recurrent ovarian cancer.
Ovarian cancer is the most lethal malignancy in gynecological oncology and is characterized by an extremely poor prognosis because of the spread of ovarian cancer cells into the peritoneal cavity (1). Epithelial ovarian cancer cells can easily and rapidly metastasize through the transcoelomic, hematogenous, or lymphatic routes (2). Thus, ovarian cancer patients are often diagnosed at an advanced stage. Cytoreductive surgery and the introduction of platinum plus taxane-based chemotherapies have improved survival in the last decade (3, 4), but the prognosis of patients with recurrent ovarian cancer remains extremely poor following treatment with standard primary chemotherapy (5-10). Moreover, there are currently no effective conventional anticancer agents for ovarian cancer patients who have recurred within 6 months of treatment (5-10). Thus, the development of novel targeted agents as well as companion diagnostics for recurrent ovarian cancer are urgently required.
Heparin-binding epidermal growth factor-like growth factor (HB-EGF) belongs to the EGF receptor (EGFR) family of ligands (11-13). Many reports have indicated HB-EGF as a rational target in breast, gastric, and ovarian cancer, as well as others (14-20). Two molecularly-target agents against HB-EGF have been reported: one is an inhibitory antibody against HB-EGF (KHK2866), and the other is BK-UM, the active ingredient of an investigational drug that was originally isolated as a non-toxic mutant form of diphtheria toxin (DT) (21-24). The administration of KHK2866 or CRM197 reduced serum HB-EGF levels of patients in phase I studies (25-27). It is important, therefore, to establish the clinical features of ovarian cancer patients with high serum expression of HB-EGF. Serum HB-EGF expression was significantly correlated with clinical stage in primary ovarian cancer, suggesting that it is involved in tumor growth and metastasis (28). Furthermore, a serum HB-EGF level of more than 230 pg/ml was also significantly correlated with clinical prognosis in patients with ovarian cancer (28). Thus, it is plausible that a serum HB-EGF level of ≥230 pg/ml may be also associated with clinical prognosis in patients with recurrent ovarian cancer.
To investigate the clinical significance of serum HB-EGF levels in recurrent ovarian cancer, clinical characteristics and outcome in patients with recurrent ovarian cancer who exhibited serum HB-EGF levels of ≥230 pg/ml were evaluated.
Materials and Methods
Patients. This study analysed serum samples from 39 patients with recurrent ovarian cancer who were treated at Fukuoka University Hospital from April 2009 to March 2014. All patients underwent cytoreductive surgery followed by platinum plus taxane-based chemotherapy as the adjuvant primary chemotherapy. None of the patients received preoperative radiotherapy or chemotherapy. Tumor stage was determined according to the International Federation of Gynaecology and Obstetrics (FIGO) staging system (29). All patients received six courses of paclitaxel and carboplatin as the adjuvant primary chemotherapy, and none had any evidence of disease at the time of the final course of the adjuvant primary chemotherapy. After completion of adjuvant primary chemotherapy, all patients were followed-up every two months for as long as there was a diagnosis of recurrent disease. When disease recurrence was confirmed, conventional chemotherapy was administered for as long as there was a diagnosis of progressive disease or for six courses in patients with stable disease (SD), partial response (PR), or complete response (CR) as for the effects of second-line chemotherapy. HB-EGF values were obtained from patient blood samples on day 1 of second-line chemotherapy. Such follow-up data include duration of follow-up, response to second-line chemotherapy, and date of death. The patients provided written informed consent, and the study was approved by the ethics committees of Fukuoka University Hospital.
Serum samples and HB-EGF ELISA. All serum samples were obtained from the 39 patients on the first day of second-line chemotherapy. Plasma was prepared by centrifugation (3,000×g for 15 min) and stored at −80°C until required. Serum HB-EGF concentrations were determined using a commercially available sandwich ELISA (DuoSet Kit; R&D Systems, Minneapolis, MN, USA). The assay was performed using a modified protocol (30) in which the concentration of capture antibody (anti-human HB-EGF antibody) was four-fold higher than in the manufacturer's protocol, and serum HB-EGF concentrations were calculated using a parallel line method.
Statistical analysis. The Mann–Whitney U-test was used for univariate analysis of the association between serum HB-EGF concentrations and clinicopathological factors. Progression-free and overall survival were calculated using the Kaplan–Meier test, with 95% confidence intervals computed by the asymmetrical method using a log-rank test. A p-value of <0.05 was considered statistically significant. Analyses were performed using GraphPad Prism (GraphPad Software, La Jolla, CA, USA).
Results
Clinical characteristics of patients. Thirty-nine patients were divided into two groups: a low group (n=31) consisting of patients with <230 pg/ml serum HB-EGF, and a high group (n=8) consisting of patients with serum HB-EGF values of ≥230 pg/ml. The clinicopathological characteristics of the patients, including age at diagnosis, histological subtype, cytoreductive surgery status, tumour stage, and HB-EGF value are described in Table I and Figure 1. The high group showed a significantly low reduction rate compared with that in the low group (p<0.05).
Association between serum HB-EGF value and clinical outcome in recurrent ovarian cancer patients. To investigate clinical outcome associated with serum HB-EGF concentration, drug resistance to conventional chemotherapy was examined in patients with recurrent ovarian cancer. All eight patients in the high group recurred within 6 months after administration of adjuvant primary chemotherapy, indicating significant drug resistance in this group compared with the low group (Table II). In addition, all patients in the high group demonstrated the same poor response to second-line chemotherapy as the adjuvant primary chemotherapy, while two, three, and seven patients in the low group exhibited complete response, partial response, or stable disease, respectively (Table III). The incidence of death from ovarian cancer within one year in the high group was significantly increased compared with the low group (Table IV). According to these lines of evidence, it is plausible that serum HB-EGF concentration is a promising biomarker in drug resistance.
Discussion
In this study, it was found that recurrent ovarian cancer patients with serum HB-EGF values of ≥230 pg/ml exhibited a poor response to standard chemotherapy as well as second-line chemotherapy compared to patients with serum HB-EGF levels of <230 pg/ml, suggesting that serum HB-EGF may be a valuable biomarker in recurrent ovarian cancer.
All patients with ≥230 pg/ml serum HB-EGF who had recurred within 6 months after primary standard chemotherapy administration, demonstrated resistance to primary standard chemotherapy as well as to second-line chemotherapy. Serum HB-EGF level is thought to be dependent on tumor volume and malignancy potential (28). In patients with ovarian cancer, tumor volume should be very small when recurrence is diagnosed after the completion of primary treatment. It is consistent, therefore, that a high level of serum HB-EGF in patients with recurrent ovarian cancer results from high cellular malignancy.
In recurrent ovarian cancer, bevacizumab or olaparib indicates a significantly favourable clinical outcome regarding prognosis (31-33). Bevacizumab is well-known as an anti-cancer agent against VEGF, a growth factor identified in colon, lung, and ovarian cancers amongst others (34, 35). However, serum VEGF expression or VEGF immunostaining are not suitable for application to companion diagnostic techniques for treatment with bevacizumab. Since VEGF expression is mediated by many pathways, VEGF in serum is probably produced by many organs and tissues including cancer tissue (34, 35). Thus, it is speculated that serum VEGF may not be influenced by the properties of cancer cells. In principle, HB-EGF promotes VEGF signalling (36-38). Therefore, bevacizumab seems to be ineffective for patients with recurrent ovarian cancer who exhibited serum HB-EGF values of ≥230 pg/ml. Olaparib, a PPAR inhibitor, has been reported to be effective for platinum-sensitive relapsed ovarian cancer (32, 33). In this study, patients with platinum-sensitive relapsed ovarian cancer had serum HB-EGF levels of <230 pg/ml. To date, there are no molecularly-targeted agents available for patients with high serum HB-EGF levels.
Clinical characteristics of the patients in this study.
Drug resistant to the adjuvant primary chemotherapy in this study.
Drug resistant to second-line chemotherapy in this study.
The incidence of death from cancer in this study.
Distribution of serum HB-EGF levels in patients with recurrent ovarian cancer. The low group included patients with serum HB-EGF values of <230 pg/ml. Closed circle indicates each serum HB-EGF value in the low group. The high group included patients with serum HB-EGF levels of ≥230 pg/ml. Closed square indicates each serum HB-EGF value in the high group. Each bar indicates the mean.
HB-EGF targeted agents have been reported in two clinical trials (26, 27): a monoclonal inhibitory antibody against HB-EGF (KHK2866), and BK-UM. Both agents can suppress high expression of serum HB-EGF. However, KHK2866 is not suitable as a cancer treatment because KHK2866 antibody induces reversible neuropsychiatric toxicity (26). BK-UM was declared to be safe and tolerable as an anticancer drug in a phase I study (27); further clinical trials for patients with high serum expression of HB-EGF would allow us to develop BK-UM or another molecularly-targeted agent against HB-EGF.
Acknowledgements
This work was supported in part by a Grant-in-Aid from the Kakihara Science and Technology Foundation (Fukuoka, Japan), a Grant-in-Aid for Young Scientists (B) (no. 227790536), and by grants from Challenging Exploratory Research (no. 26670731); Scientific Research (B) (no. 26293362); Scientific Research (C) (no. 23592470); the Central Research Institute of Fukuoka University (141011); the Center for Advanced Molecular Medicine, Fukuoka University; the Ministry of Education, Culture, Sports, Science and Technology (Tokyo, Japan); and the Princess Takamatsu Cancer Research Fund to S. Miyamoto. The Authors thank H. Nikki March, PhD, from Edanz Group (www.edanzediting.com/ac) for editing a draft of this manuscript.
Footnotes
↵* These Authors contributed equally to this study.
Conflicts of Interest
The Authors declare that they have no conflicts of interest.
- Received April 11, 2018.
- Revision received June 7, 2018.
- Accepted June 15, 2018.
- Copyright© 2018, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved
References
In this issue
Jump to section
Related Articles
Cited By...
- No citing articles found.