Combination of co-amorphization with SNEDDS outperforms Ofev® in the oral absorption of nintedanib.

Nintedanib (NTD), approved for the treatment of idiopathic pulmonary fibrosis and advanced non-small cell lung cancer, is one of brick dusts with high melting point. Although NTD has been marketed as Ofev®, a soft capsule of NTD ethanesulfonate (NTD-ESA) suspended in oil components, the oral bioavailability is quite low and highly variable. To improve the oral absorption behavior of NTD, we prepared SNEDDS formulation containing NTD-(+)-10-camphorsulfonic acid (CSA) complex with 2% HPMCP-50. CSA disrupted the high crystallinity of NTD-ESA and the formed complex, NTD-CSA, was found to be amorphous by DSC and XRPD. NTD-CSA provided solubilities in various vehicles much higher than NTD-ESA. Under the gastric luminal condition, NTD-CSA SNEDDS with or without 2% HPMCP-50 and NTD-CSA powder indicated very good dissolution of NTD from early time periods, while NTD was gradually dissolved until around 60 min from NTD-ESA and Ofev®. Under the small intestinal luminal condition, in contrast, both NTD-CSA SNEDDS formulations almost completely dissolved NTD throughout the experiments, while Ofev®, NTD-CSA, and NTD-ESA exhibited a very poor dissolution of NTD. In the in vivo absorption study, NTD-CSA SNEDDS with 2% HPMCP-50 significantly improved NTD absorption and reduced the inter-individual variation in oral absorption behavior compared with Ofev®.

Possible Regulation of P-Glycoprotein Function by Adrenergic Agonists II: Study with Isolated Rat Jejunal Sheets and Caco-2 Cell monolayers.

To clarify the regulation of drug absorption by the enteric nervous system, we investigated how adrenergic agonists (adrenaline (ADR), clonidine (CLO), dobutamine (DOB)) and dibutyryl cAMP (DBcAMP) affected P-glycoprotein (P-gp) function by utilizing isolated rat jejunal sheets and Caco-2 cell monolayers. ADR and CLO significantly decreased the secretory transport (Papptotal) of rhodamine-123 and tended to decrease the transport via P-gp (PappP-gp) and passive transport (Papppassive). In contrast, DBcAMP significantly increased and DOB tended to increase Papptotal and both tended to increase PappP-gpand Papppassive. Changes in P-gp expression on brush border membrane by adrenergic agonists and DBcAMP were significantly correlated with PappP-gp, while P-gp expression was not changed in whole cell homogenates, suggesting that the trafficking of P-gp would be responsible for its functional changes. Papppassive was inversely correlated with transmucosal or transepithelial electrical resistance, indicating that adrenergic agonists affected the paracellular permeability. Adrenergic agonists also changed cAMP levels, which were significantly correlated with PappP-gp. Furthermore, protein kinase A (PKA) or PKC inhibitor significantly decreased PappP-gp in Caco-2 cell monolayers, suggesting that they would partly contribute to the changes in P-gp activity. In conclusion, adrenergic agonists regulated P-gp function and paracellular permeability, which would be caused via adrenoceptor stimulation.

Validation of four-dimensional computed tomography without external reference respiratory signals for radiation treatment planning of lung tumors.

Deviceless four-dimensional (4D) computed tomography (CT) allows the acquisition of respiratory signals from six features without requiring an external device for cine CT processing. This method has been recently introduced in radiation treatment planning of lung tumors. To validate deviceless 4D CT, it must be compared with conventional 4D CT, which requires an external monitoring device. We compared the two methods using a multicell 4D phantom that simulates patient's movement during respiration regarding the target volume (TV), target position (TP), and internal TV for lung tumor radiation therapy. We retrospectively obtained images of 10 patients who underwent radiation treatment planning of lung tumors and compared the two methods, as in the phantom study. For the phantom study, the mean TV, root mean square errors of the TP, and mean internal TV differences between the two methods ranged from -4.5% to 1.2%, 0.7 to 2.6 mm, and -1.1% to 3.4%, respectively. The corresponding results of the clinical study ranged from -1.5% to 14.9%, 0.1 to 5.9 mm, and -9.7% to 10.1%, respectively. The results of deviceless 4D CT for the clinical study were consistent with those of conventional 4D CT, except for target movements with high excursions. Therefore, deviceless 4D CT can be an alternative to conventional 4D CT for radiation treatment planning of lung tumors.

Extensive improvement of oral bioavailability of mebendazole, a brick dust, by polymer-containing SNEDDS preparation: Disruption of high crystallinity by utilizing its counter ion.

Poorly water-soluble and poorly lipid-soluble drugs are called as "brick dust" and it is very hard for them to be formulated as some dosage form which can provide an effective bioavailability after oral administration. Mebendazole (MBZ), an anti-helminthic drug having anti-cancer properties, is one of the brick dusts and its poor bioavailability has been well known. The strategy of the current study was to improve the oral absorption of MBZ by SNEDDS formulation prepared by utilizing an MBZ-counter ion complex, of which the formation would disrupt the high crystallinity of MBZ. Among five different counter ions examined, (+)-10-camphorsulfonic acid (CSA), 2-naphthalene-sulfonic acid (NSA) and p-toluenesulfonic acid (TSA) largely improved MBZ solubility in the SNEDDS vehicle by forming the complex with MBZ. The solid state of these complexes, MBZ-CSA, MBZ-NSA and MBZ-TSA, was suggested to be amorphous by XRPD and DSC. SNEDDS formulations of the three complexes extensively improved MBZ dissolution under gastric and intestinal luminal conditions, compared with MBZ crystalline powder. However, since the dissolved concentrations of MBZ were time-dependently decreased so much by precipitation, we tried to maintain the high dissolution property by applying some polymer for SNEDDS preparation of MBZ-CSA which provided the highest solubility in the SNEDDS vehicle. Among ten different polymers examined, HPMCP-50 successfully maintained the high dissolution property of MBZ-CSA SNEDDS under both gastric and intestinal luminal conditions. In the in vivo oral administration study, SNEDDS preparations for the three MBZ complexes significantly improved MBZ absorption compared with MBZ crystalline powder, but 2% HPMCP-50-containing SNEDDS of MBZ-CSA provided further improvement of MBZ absorption, resulting in around 10-fold of crystalline powder in AUC.

Effect of Doxorubicin Release Rate From Polyethylene Glycol-Modified Liposome on Anti-tumor Activity in B16-BL6 Tumor-Bearing Mice.

To investigate the effect of doxorubicin (DOX) release rates from polyethylene glycol (PEG)-liposomes on the anti-tumor activity, several in-vitro and in-vivo studies were performed by utilizing three types of DOX-PEG-liposomes showing the slow (L-Slow), middle (L-Mid) and fast (L-Fast) release rates of DOX. L-Mid provided the highest anti-tumor activity in B16-BL6 tumor-bearing mice, although the largest amount of DOX distribution into the tumor tissue was observed in L-Slow-administered mice and the lowest was in L-Fast-administered mice. To elucidate the reason for this discrepancy, DOX distribution into cancer cells constituting the tumor tissue was determined and the highest DOX distribution into cancer cells was observed in L-Mid-administered mice. These results clearly indicate that the adequate drug release rate from liposome should make it possible to deliver the substantial amounts of drugs into cancer cells, leading to the actual anti-tumor activity.

Sequential administration of PEG-Span 80 niosome enhances anti-tumor effect of doxorubicin-containing PEG liposome.

To improve the anti-tumor effect of polyethylene glycol-modified liposome containing doxorubicin (DOX-PEG liposome), the effect of sequential administration of PEG-Span 80 niosome was investigated for Colon-26 cancer cells (C26)-bearing mice. The concept of the current study is as follows: Since both particulates would be accumulated in the tumor tissue due to the enhanced permeability and retention (EPR) effect, PEG-Span 80 niosome, mainly composed of synthetic surfactant (Span 80), would interact with DOX-PEG liposome and be a trigger to induce the release of DOX from the liposome within the tumor tissue, leading to the improvement of anti-tumor effect of DOX-PEG liposome. To find out an adequate liposome for this strategy, several PEG liposomes with different compositions were examined in terms of drug release enhancement and it was found that PEG-Span80 niosome could significantly enhance the release of calcein and DOX from a PEG liposome composed of 90% hydrogenated soybean phosphatidylcholine (HSPC) and 10% cholesterol. The sequential administration of PEG-Span 80 niosome at 24 or 48 h after dosing of DOX-PEG liposome provided a higher anti-tumor effect than the single dose of DOX-PEG liposome in the C26-bearing mice. Particularly, the 24 h-later dosing of PEG-Span 80 niosome has been found to be more effective than the 48 h-later dosing. It was also confirmed that the coexistence of PEG-Span 80 niosome with DOX-PEG liposome in 50% serum or in 50% supernatant of tumor tissue homogenate significantly increased DOX release from PEG liposome, suggesting that DOX release from DOX-PEG liposome within tumor tissue would be enhanced via the interaction with PEG-Span 80 niosome. This strategy would lead to the safer and more inexpensive chemotherapy, since it could make it possible to provide the better anti-tumor effect by utilizing the lower dose of DOX.

PC3-Secreted Microprotein Is Expressed in Glioblastoma Stem-Like Cells and Human Glioma Tissues.

Glioblastoma multiforme (GBM) is the most prevalent malignant primary brain tumor with a high recurrence rate. Despite multimodal therapy including surgical resection, chemotherapy, and radiotherapy, the median survival time after the initial diagnosis of GBM is approximately 14 months. Since cancer stem cells (CSCs) are considered the leading cause of cancer recurrence, glioblastoma stem cell-targeted therapy is a promising strategy for the treatment of GBM. However, because CSC heterogeneity has been implicated in the difficulties of CSC-target therapy, more in-depth knowledge of CSC biology is still required to develop novel therapies. In this study, we established single cell-derived tumorspheres from human glioblastoma U87MG cells. One of these tumorspheres, P4E8 clone, showed CSC-like phenotypes, such as self-renewal capacity, expression of CSC markers, resistance to anti-cancer agents, and in vivo tumorigenicity. Therefore, we used P4E8 cells as a cell-based model of glioblastoma stem cells (GSCs). Gene expression analysis using microarray indicated that the most highly expressed genes in P4E8 cells compared to the parental U87MG were PC3-secreted microprotein (MSMP). Furthermore, MSMP was expressed in patient-derived GSCs and human glioma tissues at the protein level, implying that MSMP might contribute to glioma development and progression.

Impact of four-dimensional cone-beam computed tomography on target localization for gastric mucosa-associated lymphoid tissue lymphoma radiotherapy: reducing planning target volume.

BACKGROUND: Radiotherapy of gastric mucosa-associated lymphoid tissue (MALT) lymphoma should be delivered to the entire stomach with planning target volume (PTV) that accounts for variations in stomach volume, respiratory movement, and patient set-up error. In this study, we evaluated whether the use of four-dimensional cone-beam computed tomography (4D-CBCT) reduces the PTV. METHODS: Eight patients underwent radiotherapy with 15 fractions of gastric MALT lymphoma using 4D-CBCT. PTV structures of 5-30 mm margins (5 mm intervals) from the clinical target volume (CTV) delineated based on the 4D-CT images (CTV-4D) were generated. For the target localization, we performed matching based on skin marking (skin matching), bone anatomy (bone matching), and stomach anatomy (4D soft-tissue matching) based on registration between planning CT and 4D-CBCT images from 10 phases. For each patient, we calculated the covering ratio (CR) of the stomach with variable PTV structures, based on the 4D-CBCT images, with a total of 150 phases [CR (%) = (number of covering phases/150 phases) × 100], for three target localization methods. We compared the CR values of the different target localization methods and defined the PTV with an average CR of ≥ 95% for all patients. RESULTS: The average CR for all patients increased from 17.9 to 100%, 19.6 to 99.8%, and 33.8 to 100%, in the skin, bone, and 4D soft-tissue matchings, respectively, as the PTV structures increased from 5 to 30 mm. The CR obtained by 4D soft-tissue matching was superior to that obtained by skin (P = 0.013) and bone matching (P = 0.008) for a PTV structure of 15 mm margin. The PTV required an additional margin of 20 mm (average CR: 95.2%), 25 mm (average CR: 99.1%), and 15 mm (average CR: 98.0%) to CTV-4D for the skin, bone, and 4D soft-tissue matchings, respectively. CONCLUSIONS: This study demonstrates that the use of 4D-CBCT reduces the PTV when applying 4D soft-tissue matching, compared to skin and bone matchings. Additionally, bone matching does not reduce the PTV as compared with traditional skin matching.

Semi-automated prediction approach of target shifts using machine learning with anatomical features between planning and pretreatment CT images in prostate radiotherapy.

The goal of this study was to develop a semi-automated prediction approach of target shifts using machine learning architecture (MLA) with anatomical features for prostate radiotherapy. Our hypothesis was that anatomical features between planning computed tomography (pCT) and pretreatment cone-beam computed tomography (CBCT) images could be used to predict the target, i.e. clinical target volume (CTV) shifts, with small errors. The pCT and daily CBCT images of 20 patients with prostate cancer were selected. The first 10 patients were employed for the development, and the second 10 patients for a validation test. The CTV position errors between the pCT and CBCT images were determined as reference CTV shifts (teacher data) after an automated bone-based registration. The anatomical features associated with rectum, bladder and prostate were calculated from the pCT and CBCT images. The features were fed as the input with the teacher data into five MLAs, i.e. three types of artificial neural networks, support vector regression (SVR) and random forests. Since the CTV shifts along the left-right direction were negligible, the MLAs were developed along the superior-inferior and anterior-posterior directions. The proposed framework was evaluated from the residual errors between the reference and predicted CTV shifts. In the validation test, the mean residual error with its standard deviation was 1.01 ± 1.09 mm in SVR using only one feature (one click), which was associated with positional difference of the upper rectal wall. The results suggested that MLAs with anatomical features could be useful in prediction of CTV shifts for prostate radiotherapy.

Comparison of rigid and deformable image registration for nasopharyngeal carcinoma radiotherapy planning with diagnostic position PET/CT.

PURPOSE: This observer study aimed to compare rigid image registration (RIR) with deformable image registration (DIR) for diagnostic position (DP) positron emission tomography/computed tomography (PET/CT) images in the delineation of gross tumor volumes (GTVs) in nasopharyngeal carcinoma (NPC) radiotherapy planning. MATERIALS AND METHODS: Four radiation oncologists individually delineated the GTVs, GTVRIR, and GTVDIR, on planning CT (pCT) images registered with DP-PET/CT images using RIR and B-spline-based DIR, respectively. Reference GTVs were independently delineated by all radiation oncologists using radiotherapy position (RP)-PET/CT images. DP- and RP-PET/CT images for 14 patients with NPC were acquired using early and delayed scans, respectively. Dice's similarity coefficient (DSC), mean distance to agreement, and volume agreement with reference GTVs were compared by considering the interobserver variability in reference contours. RESULTS: The average DSCs for GTVRIR and GTVDIR were 0.77 and 0.77, which were acceptable for GTV delineation. There were no statistically significant differences between GTVRIR and GTVDIR in all evaluation indexes (p > 0.05). Furthermore, the correlation between neck flexion angle differences and GTV accuracy was not statistically significant (p > 0.05). CONCLUSION: RIR was a feasible choice compared with the B-spline-based DIR in GTV delineation for NPC under variations of neck flexion angle.

ICOSLG-mediated regulatory T-cell expansion and IL-10 production promote progression of glioblastoma.

BACKGROUND: Targeting immune checkpoint proteins has recently gained substantial attention due to the dramatic success of this strategy in clinical trials for some cancers. Inducible T-cell co-stimulator ligand (ICOSLG) is a member of the B7 family of immune regulatory ligands, expression of which in cancer is implicated in disease progression due to regulation of antitumor adaptive immunity. Although aberrant ICOSLG expression has been reported in glioma cells, the underlying mechanisms that promote glioblastoma (GBM) progression remain elusive. METHODS: Here, we investigated a causal role for ICOSLG in GBM progression by analyzing ICOSLG expression in both human glioma tissues and patient-derived GBM sphere cells (GSCs). We further examined its immune modulatory effects and the underlying molecular mechanisms. RESULTS: Bioinformatics analysis and GBM tissue microarray showed that upregulation of ICOSLG expression was associated with poor prognosis in patients with GBM. ICOSLG expression was upregulated preferentially in mesenchymal GSCs but not in proneural GSCs in a tumor necrosis factor-α/nuclear factor-kappaB-dependent manner. Furthermore, ICOSLG expression by mesenchymal GSCs promoted expansion of T cells that produced interleukin-10. Knockdown of the gene encoding ICOSLG markedly reduced GBM tumor growth in immune competent mice, with a concomitant downregulation of interleukin-10 levels in the tumor microenvironment. CONCLUSIONS: Inhibition of the ICOSLG-inducible co-stimulator axis in GBM may provide a promising immunotherapeutic approach for suppressing a subset of GBM with an elevated mesenchymal signature.

Image quality evaluation of in-treatment four-dimensional cone-beam computed tomography in volumetric-modulated arc therapy for stereotactic body radiation therapy.

In this study, the image quality of in-treatment four-dimensional cone-beam computed tomography (In-4D-CBCT) obtained with various prescription doses (PDs) were quantitatively evaluated in volumetric-modulated arc therapy (VMAT) for stereotactic body radiation therapy (SBRT) of the lungs and liver. To assess image quality, we used a dynamic thorax phantom and three-dimensional (3D) abdominal phantom; In-4D-CBCT images were acquired with various PDs (from 5 to 12 Gy). The In-4D-CBCT with various PDs were compared with the reference images (pre-4D-CBCT). The image quality was evaluated using the signal-to-noise ratio (SNR), the contrast-to-noise ratio (CNR), and the Dice similarity coefficient (DSC). The fiducial marker positions with various PDs were compared with those of the reference images. For the dynamic thorax phantom, the difference between pre- and In-4D-CBCT in terms of SNR and CNR decreased, as the PD increased from 6 to 12 Gy. The median DSC ranged from 0.7 to 0.74, and showed good similarity. For the 3D abdominal phantom, the difference between pre- and In-4D-CBCT in terms of SNR and CNR decreased as the PD increased from 5 to 6 Gy; conversely, it increased as the PD increased from 7 to 8 Gy. The fiducial marker positions were within 1.0 mm for all PDs. We concluded that the image quality of In-4D-CBCT degraded compared with the reference image; however, it was sufficiently accurate for assessing the intra-fractional tumor position in VMAT for SBRT of the lungs and liver both in terms of the target volume similarity and accuracy of the fiducial marker position.

Commissioning and validation of fluence-based 3D VMAT dose reconstruction system using new transmission detector.

In this study, we evaluated the basic performance of the three-dimensional dose verification system COMPASS (IBA Dosimetry). This system is capable of reconstructing 3D dose distributions on the patient anatomy based on the fluence measured using a new transmission detector (Dolphin, IBA Dosimetry) during treatment. The stability of the absolute dose and geometric calibrations of the COMPASS system with the Dolphin detector were investigated for fundamental validation. Furthermore, multileaf collimator (MLC) test patterns and a complicated volumetric modulated arc therapy (VMAT) plan were used to evaluate the accuracy of the reconstructed dose distributions determined by the COMPASS. The results from the COMPASS were compared with those of a Monte Carlo simulation (MC), EDR2 film measurement, and a treatment planning system (TPS). The maximum errors for the absolute dose and geometrical position were - 0.28% and 1.0 mm for 3 months, respectively. The Dolphin detector, which consists of ionization chamber detectors, was firmly mounted on the linear accelerator and was very stable. For the MLC test patterns, the TPS showed a > 5% difference at small fields, while the COMPASS showed good agreement with the MC simulation at small fields. However, the COMPASS produced a large error for complex small fields. For a clinical VMAT plan, COMPASS was more accurate than TPS. COMPASS showed real delivered-dose distributions because it uses the measured fluence, a high-resolution detector, and accurate beam modeling. We confirm here that the accuracy and detectability of the delivered dose of the COMPASS system are sufficient for clinical practice.

Image quality of four-dimensional cone-beam computed tomography obtained at various gantry rotation speeds for liver stereotactic body radiation therapy with fiducial markers.

In this study, qualities of 4D cone-beam CT (CBCT) images obtained using various gantry rotation speeds (GRSs) for liver stereotactic body radiation therapy (SBRT) with fiducial markers were quantitatively evaluated. Abdominal phantom containing a fiducial marker was moved along a sinusoidal waveform, and 4D-CBCT images were acquired with GRSs of 50-200°â€¯min-1. We obtained the 4D-CBCT projection data from six patients who underwent liver SBRT and generated 4D-CBCT images at GRSs of 67-200°â€¯min-1, by varying the number of projection data points. The image quality was evaluated based on the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and structural similarity index (SSIM). The fiducial marker positions with different GRSs were compared with the setup values and a reference position in the phantom and clinical studies, respectively. The root mean square errors (RMSEs) were calculated relative to the reference positions. In the phantom study, the mean SNR, CNR, and SSIM decreased from 37.6 to 10.1, from 39.8 to 10.1, and from 0.9 to 0.7, respectively, as the GRS increased from 50 to 200°â€¯min-1. The fiducial marker positions were within 2.0 mm at all GRSs. Similarly, in the clinical study, the mean SNR, CNR, and SSIM decreased from 50.4 to 13.7, from 24.2 to 6.0, and from 0.92 to 0.73, respectively. The mean RMSEs were 2.0, 2.1, and 3.6 mm for the GRSs of 67, 100, and 200°â€¯min-1, respectively. We conclude that GRSs of 67 and 85°â€¯min-1 yield images of acceptable quality for 4D-CBCT in liver SBRT with fiducial markers.

Plan quality and delivery time comparisons between volumetric modulated arc therapy and intensity modulated radiation therapy for scalp angiosarcoma: A planning study.

INTRODUCTION: Due to its spherical surface, scalp angiosarcoma requires careful consideration for radiation therapy planning and dose delivery. Herein, we investigated whether volumetric modulated arc therapy (VMAT) is superior to intensity modulated radiation therapy (IMRT) in terms of the plan quality and delivery time. METHODS: Three different coplanar treatment plans were created for four patients, comprising a two-arc VMAT plan as well as 5-field and 9-field IMRT plans with 6 MV beams. The X-ray Voxel Monte Carlo algorithm was employed for dose calculation. A radiation therapy dose of 60 Gy was prescribed to the planning target volume (PTV) in 30 fractions. The homogeneity indexes (HIs) and conformity indexes (CIs) of the PTV, organs at risk (OARs) doses and delivery times were calculated and compared. RESULTS: For the VMAT, 5-field and 9-field IMRT plans, the mean HIs were 0.14, 0.16 and 0.15; CIs100% were 0.63, 0.61 and 0.64; CIs98% were 0.72, 0.66 and 0.70 and CIs95% were 0.74, 0.67 and 0.71 respectively. All mean dose parameters of the VMAT and 9-field IMRT plans for the brain were equal to or lower than those of the 5-field IMRT plan. For the 5-field IMRT plan, the dose constraints for the left lens were not satisfied in two patients. The mean delivery times were 3.3, 11.1 and 14.7 min for the VMAT, 5-field and 9-field IMRT plans respectively. CONCLUSION: The VMAT plan quality is comparable to that of 9-field IMRT, with a reduced delivery time. Therefore, VMAT represents a valuable, sophisticated irradiation technique for treating scalp angiosarcoma.

Validation of a method for in vivo 3D dose reconstruction in SBRT using a new transmission detector.

Stereotactic body radiation therapy (SBRT) involves the delivery of substantially larger doses over fewer fractions than conventional therapy. Therefore, SBRT treatments will strongly benefit patients using vivo patient dose verification, because the impact of the fraction is large. For in vivo measurements, a commercially available quality assurance (QA) system is the COMPASS system (IBA Dosimetry, Germany). For measurements, the system uses a new transmission detector (Dolphin, IBA Dosimetry). In this study, we evaluated the method for in vivo 3D dose reconstruction for SBRT using this new transmission detector. We confirmed the accuracy of COMPASS with Dolphin for SBRT using multi leaf collimator (MLC) test patterns and clinical SBRT cases. We compared the results between the COMPASS, the treatment planning system, the Kodak EDR2 film, and the Monte Carlo (MC) calculations. MLC test patterns were set up to investigate various aspects of dose reconstruction for SBRT: (a) simple open fields (2 × 2-10 × 10 cm2 ), (b) a square wave chart pattern, and (c) the MLC position detectability test in which the MLCs were changed slightly. In clinical cases, we carried out 6 and 8 static IMRT beams for SBRT in the lung and liver. For MLC test patterns, the differences between COMPASS and MC were around 3%. The COMPASS with the dolphin system showed sufficient resolution in SBRT. For clinical cases, COMPASS can detect small changes for the dose profile and dose-volume histogram. COMPASS also showed good agreement with MC. We can confirm the feasibility of SBRT QA using the COMPASS system with Dolphin. This method was successfully operated using the new transmission detector and verified by measurements and MC.

Establishment of a tumor sphere cell line from a metastatic brain neuroendocrine tumor.

Neuroendocrine tumors are rare, and little is known about the existence of cancer stem cells in this disease. Identification of the tumorigenic population will contribute to the development of effective therapies targeting neuroendocrine tumors. Surgically resected brain metastases from a primary neuroendocrine tumor of unknown origin were dissociated and cultured in serum-free neurosphere medium. Stem cell properties, including self-renewal, differentiation potential, and stem cell marker expression, were examined. Tumor formation was evaluated using intracranial xenograft models. The effect of temozolomide was measured in vitro by cell viability assays. We established the neuroendocrine tumor sphere cell line ANI-27S, which displayed stable exponential growth, virtually unlimited expansion in vitro, and expression of stem-cell markers such as CD133, nestin, Sox2, and aldehyde dehydrogenase. FBS-induced differentiation decreased Sox2 and nestin expression. On the basis of real-time PCR, ANI-27S cells expressed the neuroendocrine markers synaptophysin and chromogranin A. Intracranial xenotransplanted brain tumors recapitulated the original patient tumor and temozolomide exhibited cytotoxic effects on tumor sphere cells. For the first time, we demonstrated the presence of a sphere-forming, stem cell-like population in brain metastases from a primary neuroendocrine tumor. We also demonstrated the potential therapeutic effects of temozolomide for this disease.

Tumor motion changes in stereotactic body radiotherapy for liver tumors: an evaluation based on four-dimensional cone-beam computed tomography and fiducial markers.

BACKGROUND: For stereotactic body radiation therapy (SBRT) of liver tumors, tumor motion induced by respiration must be taken into account in planning and treatment. We evaluated whether liver tumor motion at the planning simulation represents liver tumor motion during SBRT, and estimated inter- and intrafractional tumor motion changes in patients undergoing liver SBRT. METHODS: Ten patients underwent four-dimensional cone-beam computed tomography (4D-CBCT) image-guided liver SBRT with abdominal compression (AC) and fiducial markers. 4D-CBCT was performed to evaluate liver tumor motion at the planning simulation, pre-, and post-SBRT. The translational distances at the center position of the fiducial markers from all 10 phases on the 4D-CBCT images were measured as the extent of the liver tumor motion in the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions. Pearson correlation coefficients were calculated to evaluate the correlation between liver tumor motion of the planning simulation and the mean liver tumor motion of the pre-SBRT. Inter- and intrafractional liver tumor motion changes were measured based on the 4D-CBCT of planning simulation, pre-, and post-SBRT. Significant inter- and intrafractional changes in liver tumor motion were defined as a change of >3 mm. RESULTS: The mean (± SD) liver tumor motion of the planning simulation 4D-CBCT was 1.7 ± 0.8 mm, 2.4 ± 2.2 mm, and 5.3 ± 3.3 mm, in the LR, AP, and SI directions, respectively. Those of the pre-SBRT 4D-CBCT were 1.2 ± 0.7 mm, 2.3 ± 2.3 mm, and 4.5 ± 3.8 mm, in the LR, AP, and SI directions, respectively. There was a strong significant correlation between liver tumor motion of the planning simulation and pre-SBRT in the LR (R = 0.7, P < 0.01), AP (R = 0.9, P < 0.01), and SI (R = 0.9, P < 0.01) directions. Significant inter- and intrafractional liver tumor motion changes occurred in 10 and 2% of treatment fractions, respectively. CONCLUSIONS: Liver tumor motion at the planning simulation represents liver tumor motion during SBRT. Inter- and intrafractional liver tumor motion changes were small in patients with AC.

Comparison of 3-dimensional dose reconstruction system between fluence-based system and dose measurement-guided system.

COMPASS system (IBA Dosimetry, Schwarzenbruck, Germany) and ArcCHECK with 3DVH software (Sun Nuclear Corp., Melbourne, FL) are commercial quasi-3-dimensional (3D) dosimetry arrays. Cross-validation to compare them under the same conditions, such as a treatment plan, allows for clear evaluation of such measurement devices. In this study, we evaluated the accuracy of reconstructed dose distributions from the COMPASS system and ArcCHECK with 3DVH software using Monte Carlo simulation (MC) for multi-leaf collimator (MLC) test patterns and clinical VMAT plans. In a phantom study, ArcCHECK 3DVH showed clear differences from COMPASS, measurement and MC due to the detector resolution and the dose reconstruction method. Especially, ArcCHECK 3DVH showed 7% difference from MC for the heterogeneous phantom. ArcCHECK 3DVH only corrects the 3D dose distribution of treatment planning system (TPS) using ArcCHECK measurement, and therefore the accuracy of ArcCHECK 3DVH depends on TPS. In contrast, COMPASS showed good agreement with MC for all cases. However, the COMPASS system requires many complicated installation procedures such as beam modeling, and appropriate commissioning is needed. In terms of clinical cases, there were no large differences for each QA device. The accuracy of the compass and ArcCHECK 3DVH systems for phantoms and clinical cases was compared. Both systems have advantages and disadvantages for clinical use, and consideration of the operating environment is important. The QA system selection is depending on the purpose and workflow in each hospital.

Dynamic positioning accuracy of a novel multileaf collimator for volumetric modulated arc therapy.

We investigated the dynamic positioning accuracy of Agility (Elekta) for volumetric modulated arc therapy (VMAT). The accuracy of the multileaf collimator (MLC) leaf position during VMAT was evaluated using three different tests: (1) a dynamic multileaf collimator (DMLC) output test with various leaf speeds, and gantry angles; (2) a slit-fence test with and without gantry rotation; and (3) a complicated VMAT plans test with dose distributions compared with measurements using gamma analysis. The DMLC output was within 1.5 % under all test conditions. The agreement between the static and VMAT in the slit-fence test was within 0.5 mm. The pass rate of each complicated VMAT test plan was more than 93.9 % ± 0.36 for gamma analysis. We confirmed the dynamic positioning accuracy of Agility, which during VMAT delivery is within VMAT tolerances. The fastest MLC was found to have the potential to offer clinical advantages, such as high-quality rapid VMAT.