Shin-ei Noda

Radiotherapy-induced anti-tumor immunity contributes to the therapeutic efficacy of irradiation and can be augmented by CTLA-4 blockade in a mouse model.

Purpose There is growing evidence that tumor-specific immune responses play an important role in anti-cancer therapy, including radiotherapy. Using mouse tumor models we demonstrate that irradiation-induced anti-tumor immunity is essential for the therapeutic efficacy of irradiation and can be augmented by modulation of cytotoxic T lymphocyte (CTL) activity. Methods and Materials C57BL/6 mice, syngeneic EL4 lymphoma cells, and Lewis lung carcinoma (LL/C) cells were used. Cells were injected into the right femurs of mice. Ten days after inoculation, tumors were treated with 30 Gy of local X-ray irradiation and their growth was subsequently measured. The effect of irradiation on tumor growth delay (TGD) was defined as the time (in days) for tumors to grow to 500 mm3 in the treated group minus that of the untreated group. Cytokine production and serum antibodies were measured by ELISA and flow cytometry. Results In the EL4 tumor model, tumors were locally controlled by X-ray irradiation and re-introduced EL4 cells were completely rejected. Mouse EL4-specific systemic immunity was confirmed by splenocyte cytokine production and detection of tumor-specific IgG1 antibodies. In the LL/C tumor model, X-ray irradiation also significantly delayed tumor growth (TGD: 15.4 days) and prolonged median survival time (MST) to 59 days (versus 28 days in the non-irradiated group). CD8(+) cell depletion using an anti-CD8 antibody significantly decreased the therapeutic efficacy of irradiation (TGD, 8.7 days; MST, 49 days). Next, we examined whether T cell modulation affected the efficacy of radiotherapy. An anti-CTLA-4 antibody significantly increased the anti-tumor activity of radiotherapy (TGD was prolonged from 13.1 to 19.5 days), while anti-FR4 and anti-GITR antibodies did not affect efficacy. Conclusions Our results indicate that tumor-specific immune responses play an important role in the therapeutic efficacy of irradiation. Immunomodulation, including CTLA-4 blockade, may be a promising treatment in combination with radiotherapy.

Radiotherapy plus Concomitant Adjuvant Temozolomide for Glioblastoma: Japanese Mono-Institutional Results

This study was conducted to investigate the feasibility and survival benefits of combined treatment with radiotherapy and temozolomide (TMZ), which has been covered by the national health insurance in Japanese patients with glioblastoma since September 2006. Between September 2006 and December 2011, 47 patients with newly diagnosed and histologically confirmed glioblastoma received radiotherapy for 60 Gy in 30 fractions. Among them, 45 patients (TMZ group) received concomitant TMZ (75 mg/m2/day, every day) and adjuvant TMZ (200 mg/m2/day, 5 days during each 28-days). All 36 of the glioblastoma patients receiving radiotherapy between January 1988 and August 2006 were analyzed as historical controls (control group). All patients were followed for at least 1 year or until they died. The median survival was 15.8 months in the TMZ group and 12.0 months in the control group after a median follow-up of 14.0 months. The hazard ratio for death in the TMZ group relative to the control group was 0.52 (P<0.01); the 2-year survival rate was 27.7% in the TMZ group and 14.6% in the control group. Hematologic toxicity of grade 3 and higher was observed in 20.4% in the TMZ group. Multivariate analysis showed that extent of surgery had the strongest impact on survival (P<0.01), while the use of TMZ had the second largest impact on survival (P = 0.035). The results indicate that combined treatment with radiotherapy and TMZ has a significant survival benefit for Japanese patients with newly diagnosed glioblastoma with slightly higher toxicities than previously reported.

Three-fraction CyberKnife radiotherapy for brain metastases in critical areas: referring to the risk evaluating radiation necrosis and the surrounding brain volumes circumscribed with a single dose equivalence of 14 Gy (V14)

The efficacy and toxicity of three-fraction CyberKnife radiotherapy were evaluated in patients with brain metastases in critical areas. One hundred and fifty-nine metastases in 145 patients including tumors >10 cm3 were treated with three-fraction CyberKnife radiotherapy with a median marginal dose of 27 Gy at a median prescribed isodose of 60%. Changes in the neurological manifestations, local tumor control and adverse effects were investigated after treatment. The surrounding brain volumes circumscribed with 23.1 Gy (single dose equivalence of 14 Gy: V14) were measured to evaluate the risk of adverse effects. Neurological manifestations, such as motor weakness, visual disturbances and aphasia improved in 26 of 97 patients (26.8%). Local tumor control was obtained in 137 of 143 metastases (95.8%) during a median follow-up of 7 months. Nine patients had symptomatic edema and three of them (2.1%) required surgical resection because of radiation necrosis. The V14 of these patients was 4.6–31.5 cm3. There were 35 lesions with a V14 of 7 cm3 or more and three of them developed extensive brain edema due to radiation necrosis. None of the patients with a V14 of <7 cm3 exhibited edema requiring an operation. We therefore conclude that a high rate of local tumor control and low rates of complications are obtained after three-fraction CyberKnife radiotherapy for metastases in critical areas. The V14 of the surrounding brain therefore seems to be a useful indicator for the risk evaluation of radiation necrosis in patients with larger metastases.

Reduction of nitric oxide level enhances the radiosensitivity of hypoxic non-small cell lung cancer

The epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (E‐TKI) resistance has emerged as an important clinical issue. To overcome this resistance, researchers have examined different modalities, either for use as a monotherapy or in combination with E‐TKI therapy. In the present study, we investigated whether a decrease in nitric oxide (NO) levels affects the radiosensitization of non‐small cell lung cancer (NSCLC) cell lines. A549 and H3255 NSCLC cells were examined. They were subjected to hypoxic conditions and monotherapy, or combined therapy using radiation and NG‐monomethyl‐l‐arginine, monoacetate (LNMMA). Reductions in nitric oxide levels enhanced the radiosensitivity of both cell lines and significantly reduced the expression of both hypoxia‐inducible factor‐1α (HIF‐1α) and EGFR in H3255 cells compared to A549 cells. Since NO is significantly associated with cell metabolism, we measured the levels of pyruvate dehydrogenase kinase‐1 (PDK‐1), reactive oxygen species, and oxygen and observed that the expression of PDK‐1 was significantly reduced. This reduction was seen simultaneously after the silencing of HIF‐1α; however, not following LNMMA treatment. The oxygen concentration was significantly increased in the treated cells, and their viability decreased in parallel. Reactive oxygen species were decreased after LNMMA and radiation treatment. Adding EGFR–TKI to cells with reduced NO levels further suppressed cell viability when combined with radiation. This study suggests that a reduction in the NO level might substantially overcome the radioresistance of mutant NSCLC cells. (Cancer Sci 2011; 102: 2150–2156)

Five-fraction CyberKnife radiotherapy for large brain metastases in critical areas: impact on the surrounding brain volumes circumscribed with a single dose equivalent of 14 Gy (V14) to avoid radiation necrosis

The efficacy and toxicity of five-fraction CyberKnife radiotherapy were evaluated in patients with large brain metastases in critical areas. A total of 85 metastases in 78 patients, including tumors >30 cm3 (4 cm in diameter) were treated with five-fraction CyberKnife radiotherapy with a median marginal dose of 31 Gy at a median prescribed isodose of 58%. Changes in the neurological manifestations, local tumor control, and adverse effects were investigated after treatment. The surrounding brain volumes circumscribed with 28.8 Gy (single dose equivalent to 14 Gy: V14) were measured to evaluate the risk of radiation necrosis. Neurological manifestations, such as motor weakness, visual disturbances and aphasia improved in 28 of 55 patients (50.9%). Local tumor control was obtained in 79 of 85 metastases (92.9%) during a median follow-up of eight months. Symptomatic edema occurred in 10 patients, and two of them (2.6%) required surgical resection because of radiation necrosis. The V14 of these patients was 3.0–19.7 cm3. There were 16 lesions with a V14 of ≥7.0 cm3, and two of these lesions developed extensive brain edema due to radiation necrosis. None of the patients with a V14 of <7.0 cm3 exhibited edema requiring surgical intervention. We therefore conclude that a high rate of local tumor control and low rates of complications can be obtained after five-fraction CyberKnife radiotherapy for large metastases in critical areas. The V14 of the surrounding brain is therefore a useful indicator for the risk of radiation necrosis in patients with large metastases.

Usefulness of Intraluminal Brachytherapy Combined With External Beam Radiation Therapy for Submucosal Esophageal Cancer: Long-Term Follow-Up Results

PURPOSE To assess the efficacy of radiation therapy (RT) by using intraluminal brachytherapy (IBT) combined with external beam RT (EBRT) for submucosal esophageal cancer. METHODS AND MATERIALS Between 1991 and 2005, 59 consecutive patients received definitive RT without chemotherapy. IBT was performed after patients completed EBRT as a booster therapy for 17 patients, using low-dose-rate Cs-137 sources until 1997, and for 19 patients, using high-dose-rate Ir-192 sources thereafter. The long-term outcomes were investigated with a median follow-up time of 61 months. RESULTS Logoregional recurrences and distant metastases were observed in 14 patients and in 2 patients in the lung, respectively, and 5 patients were rescued by salvage treatments. The 5-year logoregional control and cause-specific survival rates were 75% and 76%, respectively. The 5-year cause-specific survival rate in the EBRT group was 62%, whereas the corresponding rate in the IBT group was 86% (p = 0.04). Multivariate analysis revealed that IBT was the most powerful predictor of survival but did not reach a significant level (p = 0.07). There were five esophageal ulcers in the IBT group, but no ulcers developed with small fractions of 3 Gy. Grade 2 or higher cardiorespiratory complications developed in 2 patients (5.6%) in the IBT group and in 3 patients (13.0%) in the EBRT group. CONCLUSIONS Combining IBT with EBRT is suggested to be one of the preferable treatment modalities for medically inoperable submucosal esophageal cancer because of its preferable local control and survival probabilities, with appreciably less morbidity.

The radiobiological effectiveness of carbon-ion beams on growing neurons

Purpose: Recently carbon-ion beams have been reported to be remarkably effective for controlling various cancers with less toxicity and are thought to be a promising modality for cancer treatment. However, the biological effect of carbon-ion beams arising on normal neuron remains unknown. Therefore, this study was undertaken to investigate the effect of carbon-ion beams on neurons by using both morphological and functional assays. Materials and methods: Dorsal root ganglia (DRG) and sympathetic ganglion chains (SYMP) were isolated from day-8 and day-16 chick embryos and cultured for 20 h. Cultured neurons were exposed to carbon-ion beams and X-rays. Morphological changes, apoptosis and cell viability were evaluated with the Growth Cone Collapse (GCC), Terminal deoxynucleotidyl Transferase (TdT)-mediated deoxyUridine TriPhosphate (dUTP) nick End Labeling [TUNEL] assay and 4-[3-(4-iodophenyl)- 2-(4-nitrophenyl)- 2H-5-tetrazolio]- 1,3-benzenedisulfonate [WST-1] assays, respectively. Results: Irradiation caused GCC and neurite destruction on a time- and irradiation dose-dependent manner. Changes in morphological characteristics were similar following either irradiation. Morphological and functional assays showed that day-8 neurons were more radiosensitive than day-16 neurons, whereas, radiosensitivity of DRG was comparable to that of SYMP. The dose-response fitting curve utilising both GCC and TUNEL labeling index showed higher relative biological effectiveness (RBE) values were associated with lower lethal dose (LD) values, while lower RBE was associated with higher LD values. Conclusion: Exposure to high-linear energy transfer (LET) irradiation is up to 3.2 more efficient to induce GCC and apoptosis, in early developed neuronal cells, than low-LET irradiation. GCC is a reliable method to assess the radiobiological response of neurons.

Carbon-ion beams induce production of an immune mediator protein, high mobility group box 1, at levels comparable with X-ray irradiation

X-ray radiotherapy activates tumor antigen-specific T-cell responses, and increases in the serum levels of high mobility group box 1 (HMGB1) induced by X-ray irradiation play a pivotal role in activating anti-tumor immunity. Here, we examined whether carbon-ion beams, as well as X-rays, can induce HMGB1 release from human cancer cell lines. The study examined five human cancer cell lines: TE2, KYSE70, A549, NCI-H460 and WiDr. The proportion of cells surviving X- or carbon-ion beam irradiation was assessed in a clonogenic assay. The D10, the dose at which 10% of cells survive, was calculated using a linear–quadratic model. HMGB1 levels in the culture supernatants were assessed by an ELISA. The D10 dose for X-rays in TE2, KYSE70, A549, NCI-H460 and WiDr cells was 2.1, 6.7, 8.0, 4.8 and 7.1 Gy, respectively, whereas that for carbon-ion beams was 0.9, 2.5, 2.7, 1.8 and 3.5 Gy, respectively. X-rays and carbon-ion beams significantly increased HMGB1 levels in the culture supernatants of A549, NCI-H460 and WiDr cells at 72 h post-irradiation with a D10 dose. Furthermore, irradiation with X-rays or carbon-ion beams significantly increased HMGB1 levels in the culture supernatants of all five cell lines at 96 h post-irradiation. There was no significant difference in the amount of HMGB1 induced by X-rays and carbon-ion beams at any time-point (except at 96 h for NCI-H460 cells); thus we conclude that comparable levels of HMGB1 were detected after irradiation with iso-survival doses of X-rays and carbon-ion beams.

X Irradiation Changes Dendritic Spine Morphology and Density through Reduction of Cytoskeletal Proteins in Mature Neurons

Neurons are essential components of neural circuits and provide brain function organization. We previously reported that X irradiation induces apoptosis in immature neurons. To the best of our knowledge, there have been few reports investigating the effects of X irradiation on mature neurons. We analyzed the effects of X irradiation on the morphology, density and cytoskeletal proteins in dendritic spines on mature neurons. We prepared developing hippocampal neurons from 18 days embryo by using Bankers method. Neurons at 21 days in vitro were X irradiated at several doses and were immediately fixed. To evaluate the dendritic spine morphology and density, the neurons were transfected with a reporter plasmid for enhanced green fluorescent protein (GFP). Changes in the dendritic spines as a result of X irradiation were evaluated using electron microscopy. To analyze the cytoskeletal proteins within the dendritic spines, we performed immunocytochemistry to detect filamentous actin (F-actin), drebrin and PSD-95. X irradiation immediately changed the dendritic spine morphology, and the irradiated spines were significantly thinner and longer than the nonirradiated spines. X irradiation decreased the dendritic spine density in a dose-dependent manner. Electron microscopy confirmed these changes of dendritic spines by X irradiation. Immunohistochemical studies showed that X irradiation decreased the accumulation of drebrin and F-actin, but not PSD-95, within the dendritic spines. These results suggest that X irradiation immediately decreases the dendritic spine density and changes the morphology of mature neurons by reducing the abundance of cytoskeletal proteins. The abnormal dendritic spines may be associated with acute adverse effects after X irradiation in a clinical setting, although further investigations are warranted to validate these findings.

Impact of boost irradiation on pelvic lymph node control in patients with cervical cancer.

Radiation therapy (RT) for metastatic pelvic lymph nodes (PLNs) is not well established in cervical cancer. In this study the correlation between size of lymph nodes and control doses of RT was analyzed. Between January 2002 and December 2007, 245 patients with squamous cell carcinoma of the cervix treated with a combination of external beam irradiation with or without boost irradiation and high-dose rate brachytherapy were investigated. Size of lymph node was measured by computed tomography before RT and just after 50 Gy RT. Of the 245 patients, 78 had PLN metastases, and a total of 129 had enlarged PLNs diagnosed as metastases; 22 patients had PLN failure. The PLN control rate at 5 years was 79.5% for positive cases and 95.8% for negative cases. In cases with positive PLNs, 12 of 129 nodes (9.3%) developed recurrences. There was significant correlation between PLN control rate and size of PLN after 50 Gy (<10 mm: 96.7%, ≥ 10 mm: 75.7 % (P<0.001)). In addition, the recurrence in these poor-response nodes was significantly correlated with dose of RT. Nine of 16 nodes receiving ≤ 58 Gy had recurrence, but none of 21 nodes receiving > 58 Gy had recurrence (P = 0.0003). These results suggested that the response of lymph nodes after RT was a more significant predictive factor for recurrence than size of lymph node before RT, and poor-response lymph nodes might require boost irradiation at a total dose of > 58 Gy.