Hiromasa Kuroda

The PI3K/AKT/mTOR pathway as a therapeutic target in ovarian cancer

The phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway plays a critical role in the malignant transformation of human tumors and their subsequent growth, proliferation, and metastasis. Preclinical investigations have suggested that the PI3K/AKT/mTOR pathway is frequently activated in ovarian cancer, especially in clear cell carcinoma and endometrioid adenocarcinoma. Thus, this pathway is regarded as an attractive candidate for therapeutic interventions, and inhibitors targeting different components of this pathway are in various stages of clinical development. Here, we highlight the recent progress that has been made in our understanding of the PI3K/AKT/mTOR pathway and discuss the potential of therapeutic agents that target this pathway as treatments for ovarian cancer and the obstacles to their development.

Uterine Cervical Cancer Displaying Tumor-Related Leukocytosis : A Distinct Clinical Entity With Radioresistant Feature

BACKGROUND Tumor-related leukocytosis (TRL) is occasionally found in patients with nonhematopoietic malignancies. We investigated the clinical implication of TRL and individualized treatment for TRL-positive cervical cancer, as well as the underlying biological mechanism. METHODS Clinical data from 258 cervical cancer patients treated with definitive radiotherapy were analyzed to investigate the association between TRL and treatment outcome. Clinical samples, cervical cancer cell lines, and a mouse model of cervical cancer were used to examine the mechanisms responsible for TRL in cervical cancer, focusing on the role of tumor-derived granulocyte colony-stimulating factor (G-CSF) and myeloid-derived suppressor cells (MDSCs). All statistical tests were two-sided. RESULTS TRL was statistically significantly associated with younger age (Wilcoxon rank sum test, P = .03), larger tumor size (Wilcoxon rank sum test, P = .006), advanced clinical stage (χ(2) test, P = .01), and shorter overall survival (Cox proportional hazard modeling and Wald tests, P < .001). Among cervical cancer patients, TRL was associated with upregulated tumor G-CSF expression (χ(2) test, P < .001), elevated serum G-CSF levels (Student t test, P = .03), larger spleens (Student t test, P = .045), and increased MDSC frequencies in the blood (Student t test, P < .001) compared with the TRL-negative patients. In vitro and in vivo experiments revealed that tumor-derived G-CSF was involved in the underlying causative mechanism of TRL and MDSCs induced by tumor-derived G-CSF are responsible for the rapidly progressive and radioresistant nature of TRL-positive cervical cancer. The administration of anti-Gr-1 neutralizing antibody or the depletion of MDSCs by splenectomy (n = 6 per group) inhibited tumor growth and enhanced radiosensitivity in TRL-positive cervical cancer xenografts (Wilcoxon rank sum test, P = .008 and P = .02, respectively). CONCLUSIONS TRL is associated with resistance to radiotherapy among cervical cancer patients, and MDSC-targeting treatments may have therapeutic potential in these patients.

The significance of G-CSF expression and myeloid-derived suppressor cells in the chemoresistance of uterine cervical cancer

Granulocyte-colony stimulating factor (G-CSF) producing malignant tumor has been reported to occur in various organs, and has been associated with poor clinical outcome. The aim of this study is to investigate the significance of tumor G-CSF expression in the chemosensitivity of uterine cervical cancer. The clinical data of recurrent or advanced cervical cancer patients who were treated with platinum-based chemotherapy were analyzed. Clinical samples, cervical cancer cell lines, and a mouse model of cervical cancer were employed to examine the mechanisms responsible for the development of chemoresistance in G-CSF-producing cervical cancer, focusing on myeloid-derived suppressor cells (MDSC). As a result, the tumor G-CSF expression was significantly associated with increased MDSC frequencies and compromised survival. In vitro and in vivo experiments demonstrated that the increased MDSC induced by tumor-derived G-CSF is involved in the development of chemoresistance. The depletion of MDSC via splenectomy or the administration of anti-Gr-1 antibody sensitized G-CSF-producing cervical cancer to cisplatin. In conclusion, tumor G-CSF expression is an indicator of an extremely poor prognosis in cervical cancer patients that are treated with chemotherapy. Combining MDSC-targeting treatments with current standard chemotherapies might have therapeutic efficacy as a treatment for G-CSF-producing cervical cancer.

Preclinical Efficacy for AKT Targeting in Clear Cell Carcinoma of the Ovary

The aim of this study was to determine the role of AKT as a therapeutic target in ovarian clear cell carcinoma (CCC), an aggressive, chemoresistant histologic subtype of ovarian cancer. AKT activation was assessed by immunohistochemistry (IHC) using human tissue microarrays of primary ovarian cancers, composed of both CCC and serous adenocarcinoma (SAC). The growth-inhibitory effect of AKT-specific targeting by the small-molecule inhibitor, perifosine, was examined using ovarian CCC cell lines in vitro and in vivo. Finally, the activity of perifosine was examined using in CCC-derived tumors that had acquired resistance to anti-VEGF or chemotherapeutics such as bevacizumab or cisplatin, respectively. Interestingly, AKT was frequently activated both in early-stage and advanced-stage CCCs. Treatment of CCC cells with perifosine attenuated the activity of AKT–mTORC1 signaling, inhibited proliferation, and induced apoptosis. The effect of perifosine was more profound under conditions of high AKT activity compared with low AKT activity. Increased AKT activation and enhanced sensitivity to perifosine were observed in the context of cisplatin-resistant CCC. Treatment with perifosine concurrently with cisplatin significantly enhanced the antitumor effect of cisplatin. Moreover, perifosine showed significant antitumor activity in CCC-derived tumors that had acquired resistance to bevacizumab or cisplatin. Collectively, these data reveal that AKT is frequently activated in ovarian CCCs and is a promising therapeutic target in aggressive forms of ovarian cancer. Implications: AKT-targeted therapy has value in a first-line setting as well as a second-line treatment for recurrent disease developing after platinum-based chemotherapy or bevacizumab treatment. Mol Cancer Res; 13(4); 795–806. ©2014 AACR.

Prognostic significance of systemic neutrophil and leukocyte alterations in surgically treated endometrial cancer patients: A monoinstitutional study

OBJECTIVE The aim of this study was to investigate the prognostic significance of an elevated neutrophil count at the time of the initial diagnosis in patients with surgically treated endometrial cancer. METHODS The baseline characteristics and outcome data of patients who were diagnosed with endometrial cancer between January 2000 and December 2010 were collected and retrospectively reviewed. The patients were separated into two groups according to their neutrophil counts. The clinicopathological characteristics and overall survival rates of the two groups were compared. A Cox proportional hazard regression model was used to investigate the prognostic significance of an elevated neutrophil count among patients with surgically treated endometrial cancer. RESULTS An elevated neutrophil count was found to be associated with an advanced clinical stage (P<0.0001), lymphovascular space involvement (P=0.0003), cervical involvement (P=0.0049), the proportion of patients that received adjuvant therapy (P=0.0020), elevated NLR (P<0.0001), and treatment failure (P<0.0001). Multivariate analyses demonstrated that age (hazard ratio (HR)=2.23, 95% confidence interval (95% CI)=1.30 to 3.91; P=0.0035), clinical stage (HR=4.72, 95% CI=2.61 to 8.90; P<0.0001), lymphovascular space involvement (HR=3.15, 95% CI=1.60 to 6.68; P=0.0007), an elevated neutrophil count (HR=2.76, 95% CI=1.43 to 5.03; P=0.0033), and an elevated white blood cell count (HR=2.79, 95% CI=1.50 to 4.96; P=0.0017) were significant predictors of survival. CONCLUSION The elevated neutrophil or leukocyte counts at the time of the initial diagnosis are independent prognostic factors in patients with surgically treated endometrial cancer.

Impact of histological subtype on survival in patients with locally advanced cervical cancer that were treated with definitive radiotherapy: adenocarcinoma/adenosquamous carcinoma versus squamous cell carcinoma

Objective To compare the survival outcomes of patients with cervical squamous cell carcinoma (SCC) and adenocarcinoma/adenosquamous carcinoma (AC/ASC) among patients with locally advanced cervical cancer that were treated with definitive radiotherapy. Methods The baseline characteristics and outcome data of patients with locally advanced cervical cancer who were treated with definitive radiotherapy between November 1993 and February 2014 were collected and retrospectively reviewed. A Cox proportional hazards regression model was used to investigate the prognostic significance of AC/ASC histology. Results The patients with AC/ASC of the cervix exhibited significantly shorter overall survival (OS) (p=0.004) and progression-free survival (PFS) (p=0.002) than the patients with SCC of the cervix. Multivariate analysis showed that AC/ASC histology was an independent negative prognostic factor for PFS. Among the patients who displayed AC/ASC histology, larger tumor size, older age, and incomplete response to radiotherapy were found to be independent prognostic factors. PFS was inversely associated with the number of poor prognostic factors the patients exhibited (the estimated 1-year PFS rates; 100.0%, 77.8%, 42.8%, 0.0% for 0, 1, 2, 3 factors, respectively). Conclusion Locally advanced cervical cancer patients with AC/ASC histology experience significantly worse survival outcomes than those with SCC. Further clinical studies are warranted to develop a concurrent chemoradiotherapy (CCRT) protocol that is specifically tailored to locally advanced cervical AC/ASC.

Preclinical Investigations of PM01183 (Lurbinectedin) as a Single Agent or in Combination with Other Anticancer Agents for Clear Cell Carcinoma of the Ovary

Objective The objective of this study was to evaluate the antitumor effects of lurbinectedin as a single agent or in combination with existing anticancer agents for clear cell carcinoma (CCC) of the ovary, which is regarded as an aggressive, chemoresistant, histological subtype. Methods Using human ovarian CCC cell lines, the antitumor effects of lurbinectedin, SN-38, doxorubicin, cisplatin, and paclitaxel as single agents were assessed using the MTS assay. Then, the antitumor effects of combination therapies involving lurbinectedin and 1 of the other 4 agents were evaluated using isobologram analysis to examine whether these combinations displayed synergistic effects. The antitumor activity of each treatment was also examined using cisplatin-resistant and paclitaxel-resistant CCC sublines. Finally, we determined the effects of mTORC1 inhibition on the antitumor activity of lurbinectedin-based chemotherapy. Results Lurbinectedin exhibited significant antitumor activity toward chemosensitive and chemoresistant CCC cells in vitro. An examination of mouse CCC cell xenografts revealed that lurbinectedin significantly inhibits tumor growth. Among the tested combinations, lurbinectedin plus SN-38 resulted in a significant synergistic effect. This combination also had strong synergistic effects on both the cisplatin-resistant and paclitaxel-resistant CCC cell lines. Everolimus significantly enhanced the antitumor activity of lurbinectedin-based chemotherapies. Conclusions Lurbinectedin, a new agent that targets active transcription, exhibits antitumor activity in CCC when used as a single agent and has synergistic antitumor effects when combined with irinotecan. Our results indicate that lurbinectedin is a promising agent for treating ovarian CCC, both as a first-line treatment and as a salvage treatment for recurrent lesions that develop after platinum-based or paclitaxel treatment.

Predictors of Survival in Patients With FIGO Stage IVB Cervical Cancer.

Objective The aim of this study was to identify prognostic factors and establish a model for predicting life expectancy in International Federation of Gynecology and Obstetrics stage IVB cervical cancer patients. Methods The baseline characteristics and outcome data of patients with stage IVB cervical cancer between May 1994 and October 2014 were collected and retrospectively reviewed. A Cox proportional hazards regression model was used to identify independent predictors of survival in stage IVB cervical cancer patients. Results A total of 107 patients were included in our database. The median overall survival (OS) period was 16 months. Multivariate analysis revealed that the metastatic site (hazards ratio, 3.09; 95% confidence interval, 1.94–4.88; P < 0.0001) and a white blood cell (WBC) count exceeding 10,000/&mgr;L (hazards ratio, 2.02; 95% confidence interval, 1.19–3.30; P = 0.0102) were significant prognostic factors in terms of OS. Patient survival was inversely correlated with the number of these prognostic factors possessed. When the patients were divided into 3 prognostic groups, the median OS of the patients with 0, 1, or 2 poor prognostic factors was 26, 12, and 7 months, respectively. Among the patients with WBC counts of less than 10,000/&mgr;L, treatment with radiotherapy resulted in improved survival compared with chemotherapy or palliative care alone. In contrast, radiotherapy had minimal effects on survival in patients with WBC counts of greater than 10,000/&mgr;L. Conclusions The metastatic site and an elevated WBC count are significant prognostic factors in patients with stage IVB cervical cancer. Our prognostic model composed of these 2 clinical variables might enable physicians to predict survival more accurately.

Prognostic Significance of Pretreatment Thrombocytosis in Cervical Cancer Patients Treated With Definitive Radiotherapy.

Objective The aim of this study was to investigate the prevalence and prognostic significance of an elevated platelet count at the time of the initial diagnosis in patients with cervical cancer who are treated with definitive radiotherapy. Methods The baseline characteristics and outcome data of cervical cancer patients who were treated with definitive radiotherapy between November 1993 and December 2011 were collected and retrospectively reviewed. The patients were separated into 2 groups according to their platelet counts. The clinicopathological characteristics and overall survival rates of the 2 groups were compared. A Cox proportional hazards regression model was used to investigate the prognostic significance of an elevated platelet count. Results An elevated platelet count was found to be associated with younger age (P = 0.0003), an advanced clinical stage (P < 0.0001), larger tumors (P = 0.0025), lower hemoglobin levels (P < 0.0001), and more frequent treatment failure (P = 0.0015). Multivariate analysis demonstrated that an advanced clinical stage (hazards ratio [HR], 2.93; 95% confidence interval [CI], 1.47–6.70; P = 0.0015), nonsquamous cell carcinoma histology (HR, 2.67; 95% CI, 1.52–4.42; P = 0.0011), larger tumors (HR, 3.86; 95% CI, 2.18–7.03; P < 0.0001), lower hemoglobin levels (HR, 1.99; 95% CI, 1.34–2.93; P = 0.0008), and an elevated platelet count (HR, 1.65; 95% CI, 1.03–2.56; P = 0.0395) were significant predictors of survival. Conclusions An elevated platelet count at the time of the initial diagnosis is an independent prognostic factor in cervical cancer patients who are treated with definitive radiotherapy.

Targeting mTOR Signaling in Ovarian Cancer

The mammalian (mechanistic) target of rapamycin (mTOR) is frequently activated in epithelial ovarian cancer and is regarded as an attractive therapeutic target. Preclinical investigations using mTOR complex 1 (mTORC1) inhibitors have demonstrated promising antitumor activity on ovarian cancer both in the setting of monotherapy and in combination with cytotoxic agents. Based on promising preclinical data, mTORC1 inhibitors are currently being evaluated in phase I/II trials in patients with ovarian cancer. In an effort to overcome resistance to mTORC1 inhibitors, the novel mTOR kinase inhibitors that inhibit both mTORC1 and mTORC2, or dual PI3K/mTOR inhibitor have recently been developed. In this report, we review the scientific rationale and evidence for the potential clinical benefits provided by mTOR inhibitors for patients with epithelial ovarian cancer.