Atsushi Komaru

Sustained and NK/CD4+ T Cell-Dependent Efficient Prevention of Lung Metastasis Induced by Dendritic Cells Harboring Recombinant Sendai Virus

We recently demonstrated efficient antitumor immunity against murine tumors using dendritic cells (DCs) activated by recombinant Sendai viruses (rSeVs), and proposed a new concept, “immunostimulatory virotherapy,” for cancer immunotherapy. However, there has been little information on the efficacy of this method in preventing metastatic diseases. In this study, we investigated the efficacy of vaccinating DCs activated by fusion gene-deleted nontransmissible rSeV (rSeV/dF) using a murine model of lung metastasis. Bolus and i.v. administration of DCs harboring rSeV/dF-expressing GFP without pulsation of tumor Ag (DC-rSeV/dF-GFP) 2 days before tumor inoculation showed efficient prevention against lung metastasis of c1300 neuroblastoma, but not of RM-9 prostatic cancer. We found that the timing of DC therapy was critical for the inhibition of pulmonary metastasis of RM-9, and that the optimal effect of DCs was seen 28 days before tumor inoculation. Interestingly, the antimetastatic effect was sustained for over 3 mo, even when administered DCs were already cleared from the lung and organs related to the immune system. Although NK cell activity had already declined to baseline at the time of tumor inoculation, Ab-mediated depletion studies revealed that CD4+ cells as well as the presence of, but not the activation of, NK cells were crucial to the prevention of lung metastasis. These results are the first demonstration of efficient inhibition of lung metastasis via bolus administration of virally activated DCs that was sustained and NK/CD4+ cell-dependent, and may suggest a potentially new mechanism of DC-based immunotherapy for advanced malignancies.

Generation of optimized and urokinase-targeted oncolytic Sendai virus vectors applicable for various human malignancies

We previously reported the development of a prototype ‘oncolytic Sendai virus (SeV) vector’ formed by introducing two major genomic modifications to the original SeV, namely deletion of the matrix (M) gene to avoid budding of secondary viral particles and manipulation of the trypsin-dependent cleavage site of the fusion (F) gene to generate protease-specific sequences. As a result, the ‘oncolytic SeV’ that was susceptible to matrix metalloproteinases (MMPs) was shown to selectively kill MMP-expressing tumors through syncytium formation in vitro and in vivo. However, its efficacy has been relatively limited because of the requirement of higher expression of MMPs and smaller populations of MMP-expressing tumors. To overcome these limitations, we have designed an optimized and dramatically powerful oncolytic SeV vector. Truncation of 14-amino acid residues of the cytoplasmic domain of F protein resulted in dramatic enhancement of cell-killing activities of oncolytic SeV, and the combination with replacement of the trypsin cleavage site with the new urokinase type plasminogen activator (uPA)-sensitive sequence (SGRS) led a variety of human tumors, including prostate (PC-3), renal (CAKI-I), pancreatic (BxPC3) and lung (PC14) cancers, to extensive death through massive cell-to-cell spreading without significant dissemination to the surrounding noncancerous tissue in vivo. These results indicate a dramatic improvement of antitumor activity; therefore, extensive utility of the newly designed uPA-targeted oncolytic SeV has significant potential for treating patients bearing urokinase-expressing cancers in clinical settings.

Complete elimination of established neuroblastoma by synergistic action of |[gamma]|-irradiation and DCs treated with rSeV expressing interferon-|[beta]| gene

Dendritic cell (DC)-based immunotherapy has been investigated as a new therapeutic approach to intractable neuroblastomas; however, only limited clinical effect has been reported. To overcome the relatively low sensitivity of neuroblastomas against immunotherapy, we undertook a preclinical efficacy study to examine murine models to assess the combined effects of γ-irradiation pretreatment and recombinant Sendai virus (ts-rSeV/dF)-mediated murine interferon-β (mIFN-β) gene transfer to DCs using established c1300 neuroblastomas. Similar to intractable neuroblastomas in the clinic, established c1300 tumors were highly resistant to monotherapy with either γ-irradiation or DCs activated by ts-rSeV/dF without transgene (ts-rSeV/dF-null) that has been shown to be effective against other murine tumors, including B16F10 melanoma. In contrast, immunotherapy using DCs expressing mIFN-β through ts-rSeV/dF (ts-rSeV/dF-mIFNβ-DCs) effectively reduced tumor size, and its combination with γ-irradiation pretreatment dramatically enhanced its antitumor effect, resulting frequently in the complete elimination of established c1300 tumors 7–9 mm in diameter, in a high survival rate among mice, and in the development of protective immunity in the mice against rechallenge by the tumor cells. These results indicate that the combination of ts-rSeV/dF-mIFNβ-DCs with γ-irradiation is a hopeful strategy for the treatment of intractable neuroblastomas, warranting further investigation in the clinical setting.

Treatment outcomes of sorafenib for first line or cytokinerefractory advanced renal cell carcinoma in Japanese patients

The objective of the present study was to document the treatment efficacy and safety of sorafenib in Japanese patients with advanced renal cell carcinoma (RCC). A retrospective analysis of 50 consecutive patients with metastatic RCC between January 2005 and December 2009 was carried out. Patients received sorafenib after failed cytokine therapy or first‐line sorafenib treatment. All received 400 mg of sorafenib orally twice daily. Five of 14 patients with bone metastases were also given bisphosphonates. Tumor response was evaluated every 1–2 months according to the Response Evaluation Criteria in Solid Tumors. Adverse events (AE) were evaluated at each visit during and after treatment, and were recorded according to the National Cancer Institutes Common Terminology Criteria for Adverse Events version 3.0. Dose modification of sorafenib was permitted if grade 3 or 4 AE occurred. Treatment continued until disease progression or treatment intolerance occurred. Partial response, and stable disease as best objective responses were observed in 11 (22%) and 23 (46%) patients, respectively. Median progression‐free survival was 7.3 months and median overall survival was 11.9 months. All patients experienced AE and one or more grade 3/4 AE occurred in 43 of 50 (86%) patients. Although it requires close monitoring, sorafenib treatment seemed to be effective in the present study population.

Implications of Body Mass Index in Japanese Patients with Prostate Cancer Who Had Undergone Radical Prostatectomy

OBJECTIVE To determine the association between obesity and prostate cancer in Japanese recurrence after primary treatment with radical prostatectomy. METHODS The subjects were 173 Japanese patients with prostate cancer who had been treated with radical prostatectomy at Chiba University Hospital between April 1997 and March 2007. Clinicopathological characteristics and biochemical recurrence outcomes after radical prostatectomy were compared between the three body mass index cohorts. RESULTS Mean body mass index was 23.4 kg/m(2) with a standard deviation of 2.4, and mean follow-up period was 37.4 months. Operative time was longer and estimated blood loss was much more in obese patients. Patients with pT3>or= had significantly higher serum prostate-specific antigen, total cholesterol levels, Gleasons sum and positive of surgical margin than pT2 patients. Recurrence rate was significantly higher in the 26.5 kg/m(2) and hyperlipidemia groups in pT3>or= patients. CONCLUSIONS Obesity is an independent predictor of disease recurrence in Japanese patients with pT3>or= prostate cancer who underwent radical prostatectomy. Obese patients who underwent radical prostatectomy require vigilant follow-up care.

Efficacy of traditional and alternative sunitinib treatment schedules in Japanese patients with metastatic renal cell carcinoma

We report the adverse events and efficacy of traditional (4 weeks on 2 weeks off) and alternative sunitinib treatment schedules for Japanese patients with metastatic renal cell carcinoma. We retrospectively investigated 54 patients who received sunitinib for metastatic renal cell carcinoma between May 2006 and June 2012: 32 received a traditional treatment schedule and 22 received an alternative schedule. According to the Memorial Sloan‐Kettering Cancer Center risk classification, five patients had favorable prognoses, 42 had intermediate prognoses and seven had poor prognoses. The mean observation periods were 16.3 and 20 months for the traditional and alternative schedule groups, respectively. Adverse events were significantly less common in the alternative schedule group, including most high‐grade events. In the traditional and alternative schedule groups, median times to failure were 4.1 and 11.6 months (P = 0.040), median progression‐free survival times were 4.1 and 11.3 months (P = 0.031), and median overall survival times were 12.0 and 32.1 months (P = 0.018), respectively. Each of these measures was better in the group of patients who received an alternative treatment schedule, suggesting that individualized changes to the sunitinib administration schedule can be effective.

Development and External Validation of a Nomogram Predicting the Probability of Significant Gleason Sum Upgrading among Japanese Patients with Localized Prostate Cancer

Objective. The aim of this study is to develop a prognostic model capable of predicting the probability of significant upgrading among Japanese patients. Methods. The study cohort comprised 508 men treated with RP, with available prostate-specific antigen levels, biopsy, and RP Gleason sum values. Clinical and pathological data from 258 patients were obtained from another Japanese institution for validation. Results. Significant Gleason sum upgrading was recorded in 92 patients (18.1%) at RP. The accuracy of the nomogram predicting the probability of significant Gleason sum upgrading between biopsy and RP specimens was 88.9%. Overall AUC was 0.872 when applied to the validation data set. Nomogram predictions of significant upgrading were within 7.5% of an ideal nomogram. Conclusions. Nearly one-fifth of Japanese patients with prostate cancer will be significantly upgraded. Our nomogram seems to provide considerably accurate predictions regardless of minor variations in pathological assessment when applied to Japanese patient populations.

Cytokine-based log-scale expansion of functional murine dendritic cells

Background Limitations of the clinical efficacy of dendritic cell (DC)-based immunotherapy, as well as difficulties in their industrial production, are largely related to the limited number of autologous DCs from each patient. We here established a possible breakthrough, a simple and cytokine-based culture method to realize a log-scale order of functional murine DCs (>1,000-fold), which cells were used as a model before moving to human studies. Methodology/Principal Findings Floating cultivation of lineage-negative hematopoietic progenitors from bone marrow in an optimized cytokine cocktail (FLT3-L, IL-3, IL-6, and SCF) led to a stable log-scale proliferation of these cells, and a subsequent differentiation study using IL-4/GM-CSF revealed that 3-weeks of expansion was optimal to produce CD11b+/CD11c+ DC-like cells. The expanded DCs had typical features of conventional myeloid DCs in vitro and in vivo, including identical efficacy as tumor vaccines. Conclusions/Significance The concept of DC expansion should make a significant contribution to the progress of DC-based immunotherapy.

Prognostic models for renal cell carcinoma recurrence: External validation in a Japanese population

The aim of the present study was to compare the accuracy of three prognostic models in predicting recurrence‐free survival among Japanese patients who underwent nephrectomy for non‐metastatic renal cell carcinoma (RCC). Patients originated from two centers: Chiba University Hospital (n = 152) and Chiba Cancer Center (n = 65). The following data were collected: age, sex, clinical presentation, Eastern Cooperative Oncology Group performance status, surgical technique, 1997 tumor–node–metastasis stage, clinical and pathological tumor size, histological subtype, disease recurrence, and progression. Three western models, including Yaycioglus model, Cindolos model and Kattans nomogram, were used to predict recurrence‐free survival. Predictive accuracy of these models were validated by using Harrells concordance‐index. Concordance‐indexes were 0.795 and 0.745 for Kattans nomogram, 0.700 and 0.634 for Yaycioglus model, and 0.700 and 0.634 for Cindolos model, respectively. Furthermore, the constructed calibration plots of Kattans nomogram overestimated the predicted probability of recurrence‐free survival after 5 years compared with the actual probability. Our findings suggest that despite working better than other predictive tools, Kattans nomogram needs be used with caution when applied to Japanese patients who have undergone nephrectomy for non‐metastatic RCC.

Therapeutic outcomes of neoadjuvant and concurrent androgen-deprivation therapy and intensity-modulated radiation therapy with gold marker implantation for intermediate-risk and high-risk prostate cancer

To investigate the therapeutic outcomes of neoadjuvant and concurrent androgen‐deprivation therapy and intensity‐modulated radiation therapy with gold marker implantation for intermediate‐ and high‐risk prostate cancer.