High efficacy of particle beam therapies against tumors under hypoxia and prediction of the early stage treatment effect using 3'-deoxy-3'-[18F]fluorothymidine positron emission tomography

OBJECTIVE

Compared with radiation therapy using photon beams, particle therapies, especially those using carbons, show a high relative biological effectiveness and low oxygen enhancement ratio. Using cells cultured under normoxic conditions, our group reported a greater suppressive effect on cell growth by carbon beams than X-rays, and the subsequent therapeutic effect can be predicted by the cell uptake amount of 3'-deoxy-3'-[18F]fluorothymidine (18F-FLT) the day after treatment. On the other hand, a hypoxic environment forms locally around solid tumors, influencing the therapeutic effect of radiotherapy. In this study, the influence of tumor hypoxia on particle therapies and the ability to predict the therapeutic effect using 18F-FLT were evaluated.

METHODS

Using a murine colon carcinoma cell line (colon 26) cultured under hypoxic conditions (1.0% O2 and 5.0% CO2), the suppressive effect on cell growth by X-ray, proton, and carbon irradiation was evaluated. In addition, the correlation between decreased 18F-FLT uptake after irradiation and subsequent suppression of cell proliferation was investigated.

RESULTS

Tumor cell growth was suppressed most efficiently by carbon-beam irradiation. 18F-FLT uptake temporarily increased the day after irradiation, especially in the low-dose irradiation groups, but then decreased from 50 h after irradiation, which is well correlated with the subsequent suppression on tumor cell growth.

CONCLUSIONS

Carbon beam treatment shows a strong therapeutic effect against cells under hypoxia. Unlike normoxic tumors, it is desirable to perform 18F-FLT positron emission tomography 2-3 days after irradiation for early prediction of the treatment effect.

Exposure of the cytoplasm to low-dose X-rays modifies ataxia telangiectasia mutated-mediated DNA damage responses

We recently showed that when a low X-ray dose is used, cell death is enhanced in nucleus-irradiated compared with whole-cell-irradiated cells; however, the role of the cytoplasm remains unclear. Here, we show changes in the DNA damage responses with or without X-ray microbeam irradiation of the cytoplasm. Phosphorylated histone H2AX foci, a surrogate marker for DNA double-strand breaks, in V79 and WI-38 cells are not observed in nucleus irradiations at ≤ 2 Gy, whereas they are observed in whole-cell irradiations. Addition of an ataxia telangiectasia mutated (ATM) kinase inhibitor to whole-cell irradiations suppresses foci formation at ≤ 2 Gy. ABL1 and p73 expression is upregulated following nucleus irradiation, suggesting the induction of p73-dependent cell death. Furthermore, CDKN1A (p21) is upregulated following whole-cell irradiation, indicating the induction of cell cycle arrest. These data reveal that cytoplasmic radioresponses modify ATM-mediated DNA damage responses and determine the fate of cells irradiated at low doses.

Stability of daily rectal movement and effectiveness of replanning protocols for sparing rectal doses based on the daily CT images during proton treatment for prostate cancer

PURPOSE

To evaluate the optimal period of replanning to spare the rectal dose by investigating daily rectal movements during computed tomography (CT) image-guided proton therapy for prostate cancer.

MATERIALS AND METHODS

To evaluate the optimum reference period for replanning, we analyzed 1483 sets of daily CT (dCT) images acquired from 40 prostate cancer patients and measured the daily rectal movement along the anterior-posterior direction based on the simulator CT (sCT) images and dCT images. We calculated daily dose distributions based on initial plans on the sCT images and replans on the dCT images for 13 representative patients, and evaluated daily dose volume histograms (DVHs) for the prostate, seminal vesicles, and rectum.

RESULTS

The rectal anterior side on the dCT images around the seminal vesicles largely deviated toward the anterior side relative to the position on the reference sCT images, but the deviation decreased by referring to the dCT images and became nearly zero when we referred to the dCT images after 10-day treatment. The daily DVH values for the prostate showed good dose coverage. For six patients showing rectal movement toward the anterior side, the daily rectal DVH (V_77% ) showed a 3.0 ± 1.7 cc excess from the initial plan and this excess was correlated with 9.9 ± 6.8 mm rectal movement. To identify the patients (37.5% in total) for whom the replanning on the 10th-day and 20th-day CT images reduced the V_77% excess to 0.4 ± 1.5 cc and -0.2 ± 1.3 cc, respectively, we evaluated the accumulated mean doses with a 1.2 cc criterion.

CONCLUSION

Our data demonstrate that the daily movement of the rectal anterior side tends to move toward the anterior side, which results in a rectal overdose, and the mean of the movement gradually decreases with the passage of days. In such cases, replanning with the reference CT after 10 days is effective to spare the rectal dose.

ET-13 CONTROL OF ACTIVATED MICROGLIA THROUGH P2X4 RECEPTOR IN RADIATION BRAIN NECROSIS

INTRODUCTION

Brain radiation necrosis (RN) is severe adverse event after radiation therapy for brain tumor patients, especially in case of re-irradiation. Although corticosteroids or vitamin E, etc. are clinically used for RN, the effect is limited and underlying mechanism is to be cleared. Therefore, we established RN mouse model with irradiating right hemisphere of mouse brain using proton beam at dose of 60 Gy [Kondo et al., 2015]. In this study, we investigated change of phospholipids and lipid mediators after irradiation using this RN model in correlation with microglia activation.

METHODS

After irradiation, change of phospholipids and lipid mediators in mouse brain was investigated using imaging mass spectrometry and LC-MS. Immunohistochemistry on microglia and P2X4 receptor, a receptor for lysophosphatidylcholine (LPC) was performed.

RESULTS

In imaging mass spectrometry, 1 and 4 months after irradiation, phosphatidylcholine (PC): (16:0/20:4), (18:0/20:4) decreased in irradiated area compared non-irradiated area. On the other hand, LPC: (16:0) increased in irradiated area compared to non-irradiated area after 1 month and 4 months irradiation. PC (16:0/20:4) is a precursor of LPC (16:0) and arachidonic acid (20:4). By LC-MS, LPC was twice higher in irradiated area compared to non-irradiated, 6 months after irradiation. Microglia was highly activated in irradiated area compared to non-irradiated from 3 months after irradiation to 8 months and strongly co-expressed P2X4 receptor was confirmed in irradiated area after 6 months. Preliminary P2X4 receptor agonist administration test prolonged the RN to 12 months after irradiation.

CONCLUSION

In RN, LPC may continuously activated microglia through P2X4 receptor and cause chronic inflammation after irradiation. P2X4 agonist administration test including action resolution and immunohistochemistry is ongoing.

Biological characteristics of gene expression features in pancreatic cancer cells induced by proton and X-ray irradiation

BACKGROUND

Radiation therapy is an important alternative treatment for advanced cancer. The aim of the current study was to disclose distinct alterations of the biological characteristics of gene expression features in pancreatic cancer cells, MIAPaCa-2, following proton and X-ray irradiation.

MATERIALS AND METHODS

Using cDNA microarray, we examined the gene expression alterations of MIAPaCa-2 cells following proton or X-ray irradiation. We also isolated the surviving MIAPaCa-2 cells after irradiation and analyzed their gene expression profiles.

RESULTS

Although the cytocidal effects of both types of irradiation were similar at sufficient doses in vitro and in vivo, the affected gene expression profile alterations of MIAPaCa-2 cells irradiated with protons were distinct from those irradiated with X-ray. Interestingly, clustering analysis of gene expression of the surviving MIAPaCa-2 cells was also completely discernible between the two types of irradiation. However, a similar cytocidal effect was still observed in the proton- and X-ray-irradiated surviving cells after re-irradiation, commonly showing biological effects related to apoptosis and cell cycle processes.

CONCLUSIONS

Proton irradiation treatment for pancreatic cancer provides the distinct biological effect of steady gene expression alterations compared to X-ray irradiation; however, surviving cells from both types of irradiation were still susceptible to the cytocidal effects induced by proton re-irradiation treatment.

Positioning accuracy and daily dose assessment for prostate cancer treatment using in-room CT image guidance at a proton therapy facility

PURPOSE

To evaluate the effectiveness of CT image-guided proton radiotherapy for prostate cancer by analyzing the positioning uncertainty and assessing daily dose change due to anatomical variations.

MATERIALS AND METHODS

Patients with prostate cancer were treated by opposed lateral proton beams based on a passive scattering method using an in-room CT image-guided system. The system employs a single couch for both CT scanning and beam delivery. The patient was positioned by matching the boundary between the prostate and the rectum's anterior region identified in the CT images to the corresponding boundary in the simulator images after bone matching. We acquired orthogonal kV x-ray images after couch movement and confirmed the body position by referring to the bony structure prior to treatment. In offline analyses, we contoured the targeted anatomical structures on 375 sets of daily in-room CT images for 10 patients. The uncertainty of the image-matching procedure was evaluated using the prostate contours and actual couch corrections. We also performed dose calculations using the same set of CT images, and evaluated daily change of dose-volume histograms (DVHs) to compare the effectiveness of the treatment using prostate matching to the bone-matching procedure.

RESULTS

The isocenter shifts by prostate matching after bone matching were 0.5 ± 1.8 and -0.8 ± 2.6 mm along the superior-inferior (SI) and anterior-posterior (AP) directions, respectively. The body movement errors (σ) after couch movement were 0.7, 0.5, and 0.3 mm along the lateral, SI and AP direction, respectively, for 30 patients. The estimated errors (σ) in the prostate matching were 1.0 and 1.3 mm, and, in conjunction with the movement errors, the total positioning uncertainty was estimated to be 1.0 and 1.4 mm along the SI and AP directions, respectively. Daily DVH analyses showed that in the prostate matching, 98.7% and 86.1% of the total 375 irradiations maintained a dose condition of V_95%  > 95% for the prostate and a dose constraint of V_77%  < 18% for the rectum, whereas 90.4% and 66.1% of the total irradiations did so when bone matching was used. The dose constraint of the rectum and dose coverage of the prostate were better maintained by prostate matching than bone matching (P < 0.001). The daily variation in the dose to the seminal vesicles (SVs) was large, and only 40% of the total irradiations maintained the initial planned values of V_95% for high-risk treatment. Nevertheless, the deviations from the original value were -4 ± 7% and -5 ± 11% in the prostate and bone matching, respectively, and a better dose coverage of the SV was achieved by the prostate matching.

CONCLUSION

The correction of repositioning along the AP and SI direction from conventional bone matching in CT image-guided proton therapy was found to be effective to maintain the dose constraint of the rectum and the dose coverage of the prostate. This work indicated that prostate cancer treatment by prostate matching using CT image guidance may be effective to reduce the rectal complications and achieve better tumor control of the prostate. However, an adaptive approach is desirable to maintain better dose coverage of the SVs.

Development of the breast immobilization system in prone setup: The effect of bra in prone position to improve the breast setup error

Purpose/objective(s)

Accurate and reproducible positioning of the breast is difficult due to its deformability and softness; thus, targeting a breast tumor or tumor bed with fractionated radiotherapy using external beam radiation is difficult. The aim of this study was to develop a novel bra to aid in breast immobilization in the prone position.

Materials & methods

To assess the accuracy of prone position fixation of breast tumors, 33 breast cancer patients with 34 lesions were recruited. The bra used in this verification was customized from a commercially available bra. Duplicate MRI were acquired in the prone position, alternating with and without the bra, and for each series, patients were asked to step off the MRI table and re‐set up in the prone position. Patients were also asked to remove and re‐fit the bra for the second MRI. Each pair of images were superimposed to match the shape of the skin surface, and the maximum difference in tumor geometric center in three axes was measured. The required set up margin was calculated as: required margin = mean difference in geometric center + 2.5 standard deviation. The volumetric overlap of the tumor, as well as contouring uncertainties, was evaluated using contour analysis software.

Results

The median breast size was 498 cc. The required margins for the lateral, vertical, and longitudinal directions were estimated to be 4.1, 4.1, and 5.0 mm, respectively, with the bra, and 5.1, 6.9, and 6.7 mm, respectively, without the bra. These margins covered the dislocation of more than 33 lesions in total. With the bra, 33 lesions had achieved an objective overlap of 95% and 99% with 2 and 4 mm margins, respectively, whereas 4 and 8 mm, respectively, were needed without the bra.

Conclusion

The use of an immobilizing bra reduced the setup margin for prone position fixation of breast tumors.

A Distinct Subpopulation of Bone Marrow Mesenchymal Stem Cells, Muse Cells, Directly Commit to the Replacement of Liver Components

Genotyping graft livers by short tandem repeats after human living-donor liver transplantation (n = 20) revealed the presence of recipient or chimeric genotype cases in hepatocytes (6 of 17, 35.3%), sinusoidal cells (18 of 18, 100%), cholangiocytes (15 of 17, 88.2%) and cells in the periportal areas (7 of 8, 87.5%), suggesting extrahepatic cell involvement in liver regeneration. Regarding extrahepatic origin, bone marrow mesenchymal stem cells (BM-MSCs) have been suggested to contribute to liver regeneration but compose a heterogeneous population. We focused on a more specific subpopulation (1-2% of BM-MSCs), called multilineage-differentiating stress-enduring (Muse) cells, for their ability to differentiate into liver-lineage cells and repair tissue. We generated a physical partial hepatectomy model in immunodeficient mice and injected green fluorescent protein (GFP)-labeled human BM-MSC Muse cells intravenously (n = 20). Immunohistochemistry, fluorescence in situ hybridization and species-specific polymerase chain reaction revealed that they integrated into regenerating areas and expressed liver progenitor markers during the early phase and then differentiated spontaneously into major liver components, including hepatocytes (≈74.3% of GFP-positive integrated Muse cells), cholangiocytes (≈17.7%), sinusoidal endothelial cells (≈2.0%), and Kupffer cells (≈6.0%). In contrast, the remaining cells in the BM-MSCs were not detected in the liver for up to 4 weeks. These results suggest that Muse cells are the predominant population of BM-MSCs that are capable of replacing major liver components during liver regeneration.

Localized radiation necrosis model in mouse brain using proton ion beams

Brain radiation necrosis is the most serious late adverse event that occurs after 6 months following radiation therapy. Effective treatment for this irreversible brain necrosis has not been established yet. This study tries to establish brain radiation necrosis mouse model using proton or helium beam. The right cerebral hemispheres of C57BL/6J mouse brains were irradiated at doses of 40, 50, 60 Gy with charged particles. In 60 Gy group, brain necrosis that recapitulates human disease was detected after 8 months.

Predictive Value of Early-Stage Uptake of 3'-Deoxy-3'-18F-Fluorothymidine in Cancer Cells Treated with Charged Particle Irradiation

The aim of this study was to investigate whether 3'-deoxy-3'-(18)F-fluorothymidine ((18)F-FLT) can monitor the early response of tumor cell proliferation to charged particle irradiation in vitro and in vivo.

METHODS

In vitro, after 0.1, 0.5, 1, 5, and 10 Gy of proton or carbon ion irradiation, (18)F-FLT cell uptake was examined at 24 h and cell proliferation ability was measured from days 1 to 4. In vivo, after 0.5, 1, and 5 Gy of proton or carbon ion irradiation, (18)F-FLT PET imaging was performed on tumor-bearing BALB/c nu/nu mice at 24 h and tumor growth was measured from days 1 to 7. Tumor-to-background ratios of standardized uptake values were calculated to assess the (18)F-FLT accumulation in tumors. Both cells and mice also received x-irradiation as a control.

RESULTS

In vitro, (18)F-FLT cell uptake was significantly lower after 1 Gy of proton irradiation (P < 0.05) and carbon ion irradiation (P < 0.05) and after 5 Gy of x-irradiation (P < 0.01), but cell proliferation ability at these doses did not show significant differences until day 3. In vivo, (18)F-FLT tumor uptake was significantly lower after 1 Gy of proton (P < 0.001) and carbon ion irradiation (P < 0.01) and after 5 Gy of x-irradiation (P < 0.001), but tumor growth did not significantly differ at these doses until day 4 after proton irradiation, day 3 after carbon ion irradiation, and day 5 after x-irradiation.

CONCLUSION

The reduction in (18)F-FLT uptake after charged particle irradiation was more rapid than the change in tumor growth in vivo or the change in cell proliferation ability in vitro. Therefore, (18)F-FLT is a promising tracer for monitoring the early response of cancer to charged particle irradiation.

Relative biological effectiveness of therapeutic proton beams for HSG cells at Japanese proton therapy facilities

We investigated the relative biological effectiveness (RBE) of therapeutic proton beams at six proton facilities in Japan with respect to cell lethality of HSG cells. The RBE of treatments could be determined from experimental data. For this purpose, we used a cell survival assay to compare the cell-killing efficiency of proton beams. Among the five linear accelerator (LINAC) X-ray machines at 4 or 6 MeV that were used as reference beams, there was only a small variation (coefficient of variation CV = 3.1% at D10) in biological effectiveness. The averaged value of D10 for the proton beams at the middle position of the spread-out Bragg peak (SOBP) was 4.98. These values showed good agreement, with a CV of 4.3% among the facilities. Thus, the average RBE10 (RBE at the D10 level) at the middle position of the SOBP beam for six facilities in Japan was 1.05 with a CV of 2.8%.

Characterization of neutrons from a thick target 9Be(p, n) reaction by multiple foil activation technique for practical applications: measurement of integral cross sections and their comparison with integrated data from data files

The neutron spectrum in the energy range of 0.1 to 5.85 MeV in the 0○ direction with respect to the incident proton beam accelerated in a Tandem Accelerator of the Wakasa Wan Energy Research Center (WERC), Japan, has been characterized using the multiple foil activation technique. Flux mapping of thermal and epithermal neutrons at 0○, 20○, 40○ and 60○ at downstream of the beam has also been carried out. The fast neutron spectrum averaged cross sections of several threshold reactions were measured. Two monitor reactions, 58Ni(n, p)58Co and 115In(n, n′, γ)115mIn, were used to determine the fast neutron flux. The use of fast neutron flux in validating some excitation functions is described.

Development of a therapeutically important radiation induced promoter

Radio-genetic therapy is a combination of radiation therapy and gene therapy that may solve some of the problems associated with conventional radiotherapy. A promoter responsive to radiation was obtained from a promoter library composed of DNA fragments created by linking the TATA box signal to randomly combined binding sequences of transcription factors that are reactive to radiation. Each promoter connected to the luciferase gene, was evaluated by luciferase expression enhancement in transfected cells after X-ray irradiation. The reactivity of the best promoter was improved by the random introduction of point mutations and the resultant promoter showed more than a 20-fold enhancement of the luciferase expression after X-ray irradiation at 10 Gy. The expression of downstream genes was also enhanced in stably transfected cells not only by X-rays but also by proton beam irradiation; and either enhancement was attenuated when an anti-oxidant was added, thus suggesting the involvement of oxidative stress in the promoter activation. Constructed promoters were also activated in tumors grown in mice. In addition, cell killing with the fcy::fur gene (a suicide gene converting 5-fluorocytosin to highly toxic 5-fluorouracil) increased dose-dependently with 5-fluorocytosin only after X-ray irradiation in vitro. These results suggest that promoters obtained through this method could be used for possible clinical applications.

In de Quervain's with a separate EPB compartment, ultrasound-guided steroid injection is more effective than a clinical injection technique: a prospective open-label study

We compared ultrasonography (US)-guided injection, targeting the extensor pollicis brevis (EPB) in de Quervain's disease (dQD) with septation, to clinical injection. Forty-four wrists were randomly allocated to US-guided or manual (non-US-guided) injection. At 4 weeks, pain was significantly reduced in both groups. Pain on the 100 mm visual analogue scale (VAS) for the US group was 80.3 (SD 19.6) mm at baseline and 25.6 (SD 15.1) mm at 4 weeks after injection (p = 0.004). Values for the manual group were 78.0 (SD 18.5) mm at baseline and 58.2 (SD 21.9) mm at 4 weeks after injection (p = 0.04). Pain on the VAS showed a more significant decrease in the US-guided than in the manual injection group (p = 0.0007) from baseline to 4 weeks after injection. The results of this study suggest US-guided injection targeting the EPB in dQD patients with septation is more effective than manual injection.

A loss-of-function p.G191R variant in the anionic trypsinogen (PRSS2) gene in Japanese patients with pancreatic disorders

OBJECTIVE

There is a concept that pancreatitis results from an imbalance of proteases and their inhibitors within the pancreatic parenchyma. It has been recently shown that a loss-of-function variant, c.571G>A (p.G191R), in the anionic trypsinogen (PRSS2) gene protects against chronic pancreatitis in European populations. Here we examined the association of the p.G191R variant with pancreatic disorders in Japan.

METHODS

Genomic DNA was prepared from 378 healthy controls and 604 patients with pancreatic disorders (241 patients with chronic pancreatitis, 174 with acute pancreatitis, and 189 with pancreatic neoplasm). Mutational analysis of the PRSS2 gene was performed by polymerase chain reaction-restriction fragment length polymorphism and direct sequencing.

RESULTS

The heterozygous p.G191R variant was found in three of 241 (1.2%) patients with chronic pancreatitis, in seven of 174 (4.0%) patients with acute pancreatitis, and in 12 of 189 (6.3%) patients with pancreatic neoplasm. The p.G191R variant was found in 25 (two were homozygous and 23 were heterozygous) of 378 (6.6%) healthy controls. The p.G191R frequency in patients with chronic pancreatitis was lower than that in healthy controls (p = 0.001; odds ratio (OR) 0.178; 95% confidence interval (CI) = 0.057 to 0.561). The p.G191R frequency was lower in patients with alcoholic (0.9%; p = 0.015; OR, 0.132; 95% CI, 0.022 to 0.779) and idiopathic (1.0%; p = 0.025; OR, 0.144; 95% CI, 0.025 to 0.851) chronic pancreatitis than that in healthy controls. There were no statistical differences in the p.G191R frequency between healthy controls and patients with acute pancreatitis or with pancreatic neoplasm. Patients with alcoholic acute pancreatitis (n = 59) had no variant carrier, and the p.G191R frequency was lower than that in healthy controls (p = 0.035).

CONCLUSION

The p.G191R variant protected against alcoholic and idiopathic chronic pancreatitis as well as alcoholic acute pancreatitis in Japan.

Endoscopic mucosal resection for early gastric cancer: comparison of two modifications of the cap method

BACKGROUND AND STUDY AIM

Endoscopic mucosal resection using a cap (EMR-C) is an established method for curative resection of early neoplastic lesions; prelooping of the snare may however be difficult and lead to imprecise resection. We therefore compared two modifications of the conventional technique using outer snare placement with an accessory channel in a prospective, nonrandomized study.

PATIENTS AND METHODS

Between October 2004 and March 2007, 54 patients (men 37, women 17; mean age 71 years) underwent EMR. One method involved an internally retained snare (IRS) cap, with a fixed prelooped snare inside the cap; the other method used an externally guided snare (EGS) cap with the snare guided over an oblique cap. The main outcome parameters were specimen size, en bloc resection, and complications.

RESULTS

There was no difference between use of the IRS and EGS cap methods in relation to specimen size (27.6 vs. 27.1 mm), or rates of en bloc resection (88.9 % vs. 83.3 %); only one perforation occurred, and this was in the EGS group.

CONCLUSION

Both techniques appeared to provide similar efficacy, the inner rim of the IRS cap stabilizes aspiration of the lesion compared with the EGS cap that does not have it.