Tomoyuki Sasano

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.

Potential Role of mTORC2 as a Therapeutic Target in Clear Cell Carcinoma of the Ovary

The goal of this study was to examine the role of mTOR complex 2 (mTORC2) as a therapeutic target in ovarian clear cell carcinoma (CCC), which is regarded as an aggressive, chemoresistant histologic subtype. Using tissue microarrays of 98 primary ovarian cancers [52 CCCs and 46 serous adenocarcinomas (SAC)], activation of mTORC2 was assessed by immunohistochemistry. Then, the growth-inhibitory effect of mTORC2-targeting therapy, as well as the role of mTORC2 signaling as a mechanism for acquired resistance to the mTOR complex 1 (mTORC1) inhibitor RAD001 in ovarian CCC, were examined using two pairs of RAD001-sensitive parental (RMG2 and HAC2) and RAD001-resistant CCC cell lines (RMG2-RR and HAC2-RR). mTORC2 was more frequently activated in CCCs than in SACs (71.2% vs. 45.7%). Simultaneous inhibition of mTORC1 and mTORC2 by AZD8055 markedly inhibited the proliferation of both RAD001-sensitive and -resistant cells in vitro. Treatment with RAD001 induced mTORC2-mediated AKT activation in RAD001-sensitive CCC cells. Moreover, increased activation of mTORC2–AKT signaling was observed in RAD001-resistant CCC cells compared with the respective parental cells. Inhibition of mTORC2 during RAD001 treatment enhanced the antitumor effect of RAD001 and prevented CCC cells from acquiring resistance to RAD001. In conclusion, mTORC2 is frequently activated, and can be a promising therapeutic target, in ovarian CCCs. Moreover, mTORC2-targeted therapy may be efficacious in a first-line setting as well as for second-line treatment of recurrent disease developing after RAD001-treatment. Mol Cancer Ther; 12(7); 1367–77. ©2013 AACR.

Impact of the addition of concurrent chemotherapy to pelvic radiotherapy in surgically treated stage IB1-IIB cervical cancer patients with intermediate-risk or high-risk factors: a 13-year experience.

Objectives To identify groups of patients who derive clinical benefit from postoperative adjuvant concurrent chemoradiotherapy (CCRT), we retrospectively investigated the survival outcomes of surgically treated early-stage cervical cancer patients. Methods We reviewed the medical records of 316 patients with FIGO stage IB1-IIB cervical cancer who had been treated with adjuvant radiotherapy (RT) (n = 124, RT group) or adjuvant CCRT (n = 192, CCRT group) after radical hysterectomy between January 1996 and December 2009. Of these, 187 patients displayed high-risk prognostic factors (high-risk group), and 129 displayed intermediate-risk prognostic factors (intermediate-risk group). Sixty patients with 1 intermediate-risk prognostic factor who received no adjuvant therapy were also identified and used as controls (NFT group). Survival was calculated using the Kaplan-Meier method and compared using the log-rank test. Results In the high-risk group, adjuvant CCRT was significantly superior to RT alone with regard to recurrence rate, progression-free survival (PFS), and overall survival. In the intermediate-risk group, CCRT was superior to RT with regard to recurrence rate and PFS in patents with 2 or more risk factors. Among the patients with only 1 intermediate-risk factor, although no survival benefit of CCRT over RT was observed, addition of adjuvant treatment resulted in significantly improved PFS compared with the NFT group in patients with deep stromal invasion (log-rank, P = 0.012). Conclusions Postoperative CCRT improved the prognosis of FIGO stage IB1-IIB cervical cancer patients in the high-risk group and patients who displayed 2 or more intermediate-risk factors. Patients who displayed deep stromal invasion alone also derived clinical benefit from adjuvant treatment.

Reirradiation using high-dose-rate interstitial brachytherapy for locally recurrent cervical cancer: a single institutional experience.

Objectives This study aimed to evaluate the effectiveness and feasibility of reirradiation using high-dose-rate interstitial brachytherapy (HDR-ISBT) in patients with recurrent cervical cancer. Methods The records of 52 consecutive women with central pelvic recurrence who were salvaged with HDR-ISBT–based reirradiation were retrospectively reviewed. Data regarding the primary disease, follow-up findings, recurrence, the treatment outcome, and toxicities were collected. Multivariate analysis was performed using the Cox proportional hazards regression model to identify predictors of the response to HDR-ISBT. Survival rate was calculated using the Kaplan-Meier method and compared using the log-rank test. Results A total of 52 patients who had been treated with HDR-ISBT–based reirradiation were included in our database. The local control rate was 76.9% (40/52), and the median postrecurrence survival period was 32 months. Grade 3 or 4 late toxicities were observed in 13 patients (25%). Multivariate analysis revealed that tumor size and the treatment-free interval were significant poor prognostic factors of postrecurrence survival. In a comparison between the patients who were salvaged with HDR-ISBT–based reirradiation (ISBT group) and those who were treated with palliative therapy alone (palliative group), we found that among the patients who displayed 0 or 1 poor prognostic factors, the patients in the ISBT group survived significantly longer than those in the palliative group. In contrast, similar survival rates were seen in both groups among the patients with 2 or more poor prognostic factors. Conclusions Reirradiation using HDR-ISBT is effective and feasible in patients with recurrent cervical cancer. Our 2-clinical variable prognostic model might enable physicians to identify patients who would not derive clinical benefit from HDR-ISBT and offer them the opportunity to receive other types of treatment.

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.

Utility of serum squamous cell carcinoma antigen levels at the time of recurrent cervical cancer diagnosis in determining the optimal treatment choice

Objective To investigate the utility of serum squamous cell carcinoma antigen (SCC-Ag) levels upon the diagnosis of recurrent cervical cancer for decision making in patient management. Methods Clinical records from 167 cervical cancer patients who developed recurrence between April 1996 and September 2010 were reviewed. A Cox proportional hazards regression model was used to investigate the prognostic significance of serum SCC-Ag levels at the time of recurrence. The effects of various salvage treatments on survival outcomes of recurrent cervical cancer were examined with respect to serum SCC-Ag levels. Results Serum SCC-Ag levels were elevated (>2.0 ng/mL) in 125 patients (75%) when recurrence was diagnosed. These patients exhibited significantly shorter postrecurrence survival than those with normal SCC-Ag levels (log-rank; p=0.033). Multivariate analyses revealed that an elevated serum SCC-Ag level was an independent prognostic factor for poor postrecurrence survival. In patients with SCC-Ag levels <14.0 ng/mL, radiotherapy or surgery resulted in improved survival compared with chemotherapy or supportive care. In contrast, in patients with SCC-Ag levels of ≥14.0 ng/mL, salvage treatment with radiotherapy had only a minimal impact on postrecurrence survival. Conclusion The serum SCC-Ag level measured when cervical cancer recurrence is diagnosed can be useful for deciding upon the appropriate salvage treatment.

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.