DCE-MRI biomarkers for monitoring an anti-angiogenic triple combination therapy in experimental hypopharynx carcinoma xenografts with immunohistochemical validation.

BACKGROUND: Novel anti-angiogenic treatments are increasingly complementing established cancer therapy strategies in head and neck tumors. Contrast-enhanced magnetic resonance imaging (MRI) can be applied for early and non-invasive therapy monitoring by non-invasive quantitative assessment of tumor microcirculation as in vivo imaging biomarkers of therapy response. PURPOSE: To monitor the anti-angiogenic effects of a novel combination therapy on experimental head and neck squamous cell carcinomas (HNSCC) with dynamic contrast-enhanced (DCE)-MRI. MATERIAL AND METHODS: Athymic rats (n = 18) with subcutaneous HNSCC xenografts were investigated by DCE-MRI before and after 7 days of a daily triple therapy regimen combining the COX-II-inhibitor celecoxib, the matrix-metalloproteinase-inhibitor GM6001, and the uPA-inhibitor upamostat. Quantitative measurements of tumor blood flow (tBF), tumor blood volume (tBV), and permeability-surface area product (PS) were calculated and validated by immunohistochemistry. RESULTS: Mean tBF and tBV in triple-therapy animals decreased significantly from day 0 to day 7 (tBF, 41.0 ± 14.2 to 20.4 ± 5.7 mL/100 mL/min; P < 0.01; tBV, 17.7 ± 3.9 to 7.5 ± 3.3%; P < 0.01). No significant effects on PS were observed in either group (P > 0.05). Immunohistochemical analysis showed a significantly lower tumor vascularity in the therapy group than in the control group (CD31), significantly fewer Ki-67+ proliferating tumor cells and significantly more Capase-3+ apoptotic tumor cells (P < 0.05). Significant (P < 0.05) correlations were observed between tBF/tBV and CD31 (tBF, r = 0.84; tBV, r = 0.70), tBV and Ki-67 (r = 0.62), as well as tBF and caspase-3 (r = -0.64). CONCLUSION: DCE-MRI may be a suitable tool for the non-invasive monitoring of the anti-vascular effects of this innovative triple therapy regimen with potential for clinical translation.

Concomitant gemcitabine therapy negatively affects DC vaccine-induced CD8(+) T-cell and B-cell responses but improves clinical efficacy in a murine pancreatic carcinoma model.

BACKGROUND: Multiple studies have shown that dendritic cell (DC)-based vaccines can induce antitumor immunity. Previously, we reported that gemcitabine enhances the efficacy of DC vaccination in a mouse model of pancreatic carcinoma. The present study aimed at investigating the influence of gemcitabine on vaccine-induced anti-tumoral immune responses in a syngeneic pancreatic cancer model. MATERIALS AND METHODS: Subcutaneous or orthotopic pancreatic tumors were induced in C57BL/6 mice using Panc02 cells expressing the model antigen OVA. Bone marrow-derived DC were loaded with soluble OVA protein (OVA-DC). Animals received gemcitabine twice weekly. OVA-specific CD8(+) T-cells and antibody titers were monitored by FACS analysis and ELISA, respectively. RESULTS: Gemcitabine enhanced clinical efficacy of the OVA-DC vaccine. Interestingly, gemcitabine significantly suppressed the vaccine-induced frequency of antigen-specific CD8(+) T-cells and antibody titers. DC migration to draining lymph nodes and antigen cross-presentation were unaffected. Despite reduced numbers of tumor-reactive T-cells in peripheral blood, in vivo cytotoxicity assays revealed that cytotoxic T-cell (CTL)-mediated killing was preserved. In vitro assays revealed sensitization of tumor cells to CTL-mediated lysis by gemcitabine. In addition, gemcitabine facilitated recruitment of CD8(+) T-cells into tumors in DC-vaccinated mice. T- and B-cell suppression by gemcitabine could be avoided by starting chemotherapy after two cycles of DC vaccination. CONCLUSIONS: Gemcitabine enhances therapeutic efficacy of DC vaccination despite its negative influence on vaccine-induced T-cell proliferation. Quantitative analysis of tumor-reactive T-cells in peripheral blood may thus not predict vaccination success in the setting of concomitant chemotherapy.

Quantification of coronary artery calcium on the basis of dual-energy coronary CT angiography.

PURPOSE: To evaluate the feasibility of using virtual noncontrast material-enhanced (VNC) computed tomographic (CT) series derived from dual-energy CT imaging studies for coronary artery calcium quantification. MATERIALS AND METHODS: This HIPAA-compliant study was institutional review board approved; all patients provided written informed consent. Thirty-six patients prospectively underwent noncontrast-enhanced CT calcium scoring followed by coronary CT angiography performed in dual-energy mode. By using different reconstruction algorithms, three VNC series were generated and evaluated for noise and efficiency of virtual iodine removal. Two readers independently quantified calcium on VNC images and true noncontrast-enhanced conventional calcium scoring series. A leave-one-out cross validation was used to assess the accuracy of calcium score prediction from VNC series by means of linear regression. RESULTS: CT value histograms of the VNC series closely resembled the profile in the true noncontrast-enhanced series. There was excellent correlation between calcium volumes on the VNC series and true noncontrast-enhanced series on a per-patient (r = 0.94, P < .001, n = 36) and per-vessel (r = 0.94, 0.91, and 0.92 for the three coronary arteries, all P < .001, n = 36 each) level. The ability of a linear regression model to predict actual calcium scores from calcium volumes on VNC series was excellent (r = 0.82). Multiethnic Study of Atherosclerosis rankings that were derived from the predicted calcium scores also showed excellent agreement (intraclass correlation coefficient = 0.909). CONCLUSION: Coronary artery calcium identification and quantification based on dual-energy coronary CT angiographic studies may obviate the need for dedicated CT calcium scoring studies.

Dendritic cell-based vaccination of patients with advanced pancreatic carcinoma: results of a pilot study.

BACKGROUND AND AIMS: Dendritic cell (DC)-based vaccination can induce antitumor T cell responses in vivo. This clinical pilot study examined feasibility and outcome of DC-based tumor vaccination for patients with advanced pancreatic adenocarcinoma. METHODS: Tumor lysate of patients with pancreatic carcinoma was generated by repeated freeze-thaw cycles of surgically obtained tissue specimens. Patients were eligible for DC vaccination after recurrence of pancreatic carcinoma or in a primarily palliative situation. DC were generated from peripheral blood mononuclear cells (PBMC), loaded with autologous tumor lysate, stimulated with TNF-α and PGE(2) and injected intradermally. All patients received concomitant chemotherapy with gemcitabine. Disease response was the primary endpoint. Individual immunological responses to DC vaccination were analyzed by T cell-based immunoassays using pre- and post-vaccination samples of non-adherent PBMC. RESULTS: Twelve patients received DC vaccination and concomitant chemotherapy. One patient developed a partial remission, and two patients remained in stable disease. Median survival was 10.5 months. No severe side effects were observed. Tumor-reactive T cells could be detected prior to vaccination. DC vaccination increased the frequency of tumor-reactive cells in all patients tested; however, the degree of this increase varied. To quantify the presence of tumor-reactive T cells, stimulatory indices (SI) were calculated as the ratio of proliferation-inducing capacity of lysate-loaded versus -unloaded DC. The patient with longest overall survival of 56 months had a high SI of 6.49, indicating that the presence of a pre-vaccination antitumor T cell response might be associated with prolonged survival. Five patients survived 1 year or more. CONCLUSION: DC-based vaccination can stimulate an antitumoral T cell response in patients with advanced or recurrent pancreatic carcinoma receiving concomitant gemcitabine treatment.

Organ doses to adult patients for chest CT.

PURPOSE: The goal of this study was to estimate organ doses for chest CT examinations using volume computed tomography dose index (CTDIvol) data as well as accounting for patient weight. METHODS: A CT dosimetry spreadsheet (ImPACT CT patient dosimetry calculator) was used to compute organ doses for a 70 kg patient undergoing chest CT examinations, as well as volume computed tomography dose index (CTDIvol) in a body CT dosimetry phantom at the same CT technique factors. Ratios of organ dose to CTDIvoI (f(organ)) were generated as a function of anatomical location in the chest for the breasts, lungs, stomach, red bone marrow, liver, thyroid, liver, and thymus. Values of f(organ) were obtained for x-ray tube voltages ranging from 80 to 140 kV for 1, 4, 16, and 64 slice CT scanners from two vendors. For constant CT techniques, we computed ratios of dose in water phantoms of differing diameter. By modeling patients of different weights as equivalent water cylinders of different diameters, we generated factors that permit the estimation of the organ doses in patients weighing between 50 and 100 kg who undergo chest CT examinations relative to the corresponding organ doses received by a 70 kg adult. RESULTS: For a 32 cm long CT scan encompassing the complete lungs, values of f(organ) ranged from 1.7 (thymus) to 0.3 (stomach). Organs that are directly in the x-ray beam, and are completely irradiated, generally had f(organ), values well above 1 (i.e., breast, lung, heart, and thymus). Organs that are not completely irradiated in a total chest CT scan generally had f(organ) values that are less than 1 (e.g., red bone marrow, liver, and stomach). Increasing the x-ray tube voltage from 80 to 140 kV resulted in modest increases in f(organ) for the heart (9%) and thymus (8%), but resulted in larger increases for the breast (19%) and red bone marrow (21%). Adult patient chests have been modeled by water cylinders with diameters between approximately 20 cm for a 50 kg patient and approximately 28 cm for a 100 kg patient. At constant x-ray techniques, a 50 kg patient is expected to have doses that are approximately 18% higher than those in a 70 kg adult, whereas a 100 kg patient will have doses that are apparoximately 18% lower. CONCLUSIONS: We describe a practical method to use CTDI data provided by commercial CT scanners to obtain patient and examination specific estimates of organ dose for chest CT examinations.

Intraosseous needles in pediatric cadavers: Rate of malposition.

AIM OF THE STUDY: Intraosseous vascular access is a commonly conducted procedure especially in pediatric resuscitation. Very high success rates for intraosseous (IO) devices are reported. Aim of the study was to describe the rates of malposition of intraosseous needles (ION) in pediatric cadavers via post-mortem computed tomography (PMCT). METHODS: 212 consecutive pediatric cadavers underwent PMCT, of which 38 cadavers had visible ION and were included in the study. They were divided into two subgroups depending on their age (n = 22 infant cadavers (age <1 year) and n = 16 child cadavers (age ≥1 year)). Two independent readers evaluated the number and position of ION. RESULTS: In 22 infant cadavers 34 ION were found. Malposition of at least one ION was visible in 14 subjects (64%), among which 7 cadavers (32%) even had no correctly placed ION, thus being without established vascular access. Overall, 16 of the 34 used ION devices (47%) were in malposition. 23 ION were found in 16 child cadavers. In 8 subjects (50%) at least one ION was malpositioned, among which 3 cadavers (19%) had no correctly placed ION, resulting in a complete absence of vascular access. Overall, 9 of the 23 ION devices (39%) were malpositioned. CONCLUSION: Our study showed relatively high malposition rates for ION devices in pediatric cadavers which was not to be assumed regarding the success rates of 80% and higher in previous literature. This should be clarified by further studies in living patients.

Improved prediction of nephron-sparing surgery versus radical nephrectomy by the optimized R.E.N.A.L. Score in patients undergoing surgery for renal masses.

BACKGROUND: One major objective of currently available morphometric scores (MS) for renal masses, i.e., R.E.N.A.L., PADUA classification, Centrality-Index, is the prediction of type of surgery (nephron-sparin surgery [NSS] or radical nephrectomy [RN]). METHODS: Based on a prospective study protocol, various MS were assigned and calculated for 108 patients undergoing surgical treatment for renal masses at a single academic center. MS calculation was based on preoperative computed-tomography or magnet-resonance-imaging and performed by two independent readers blinded for surgical approach and outcome. Multivariable logistic-regression- and ROC-analyses were performed to assess the predictive value of various MS for surgical approach and the correlation of clinical parameters with nephrectomy type. Furthermore, the association with perioperative outcome parameters was evaluated. RESULTS: None of the tested MS was significantly superior to tumor size alone (area under the curve [AUC]=0.82) in predicting RN, with Centrality-Index showing the best association (AUC=0.88). Based on these findings, a simplified and optimized R.E.N.A.L. Score (optR.E.N.A.L.) was developed with different weightings of included parameters, which did not only show a significantly enhanced association with surgery type (AUC=0.93) than tumor size, but also outperformed all 1st and 2nd generation MS tested in the study cohort. Besides a modest correlation with postoperative change in renal function, no association with perioperative outcome variables was found for all MS including optR.E.N.A.L. CONCLUSIONS: optR.E.N.A.L. represents a promising improvement of the preexisting R.E.N.A.L. Score with higher predictive ability for nephrectomy type than established MS and may serve as a benchmarking tool for nephrectomy assessment and comparison of surgical strategies.

Proapoptotic and antiapoptotic proteins of the Bcl-2 family regulate sensitivity of pancreatic cancer cells toward gemcitabine and T-cell-mediated cytotoxicity.

Sensitivity of carcinoma cells towards gemcitabine (Gem) has been linked to mitochondrial apoptotic proteins. Recently, we described synergistic efficacy of Gem-based chemoimmunotherapy and a dendritic cell (DC) tumor vaccine in a murine pancreatic carcinoma model. Here, we investigated the role of the mitochondrial proteins Bcl-2, Bcl-xL, and Bax for sensitization of pancreatic carcinoma cells toward T-cell-mediated cytotoxicity alone and in combination with Gem. Bcl-2 expression was silenced by siRNA in Panc02 pancreatic cancer cells expressing the model antigen ovalbumin (PancOVA). Tumor cells were treated with Gem and/or siRNA, and cytotoxicity induced by OVA-specific cytotoxic T lymphocytes (CTL) from OT-1 mice was assessed. Gem-induced and T-cell-induced cytotoxicity was also studied in human Colo357 pancreatic cancer cell lines overexpressing Bax or Bcl-xL. Apoptosis induction by Fas-activating antibody was measured by Annexin V staining. The in vivo capacity of Bcl-2 siRNA to augment CTL efficacy induced by DC vaccinations was assessed in C57BL/6 mice bearing PancOVA tumors. PancOVA cells treated with Bcl-2 siRNA were sensitized towards both Gem and T-cell-mediated killing; combination therapy exhibited an additive effect. Bax overexpression sensitized Colo357 cells to both Gem-mediated and T-cell-mediated cytotoxicity, whereas Bcl-xL overexpression was inhibitory. Combining Bcl-2 silencing with DC therapy improved tumor control in the PancOVA model in vivo without affecting the number of tumor-reactive CTL. In conclusion, expression of Bcl-2, Bcl-xL, and Bax in pancreatic tumor cells determines sensitivity towards both Gem-mediated and CTL-mediated toxicity. Bcl-2 silencing could be exploited therapeutically in tumor vaccine approaches.

X-ray beam filtration, dosimetry phantom size and CT patient dose conversion factors.

We examine how the choice of CT x-ray beam filtration and phantom size influences patient dose (D) to computed tomography dose index (CTDI) conversion factors (i.e. D/CTDI). The ratio of head to body phantom CTDI(w) for a defined scan technique is alpha, and the ratio of organ dose when the body filter is changed to the head filter is beta. CTDI and organ doses were obtained using the ImPACT CT patient dosimetry calculator, and values of alpha and beta were determined for 39 CT scanners. The average value of alpha for the 39 CT scanners covering a 20 year period was 1.99 +/- 0.23, but 30% of scanners had alpha values that differed by more than 10% from the average. For GE, the value of alpha has been approximately constant at approximately 2.0. Both Philips and Siemens show a definite upward trend from values well below 2.0 in the early 1990s to well over 2.0 for their latest models. The data for Toshiba show no overall trend with time with half the data points below 2.0 and the remainder above this value. The average value of beta was 1.09 +/- 0.25. All vendors showed a downward trend in the beta parameter, and where the most recent scanners from each vendor had a beta value close to unity. Our results show that average D/CTDI conversion factors for a body phantom/filter combination are typically double those appropriate for a head phantom/filter combination.

Computing effective dose in cardiac CT.

We present a method of estimating effective doses in cardiac CT that accounts for selected techniques (kV mAs(-1)), anatomical location of the scan and patient size. A CT dosimetry spreadsheet (ImPACT CT Patient Dosimetry Calculator) was used to estimate effective doses (E) using ICRP 103 weighting factors for a 70 kg patient undergoing cardiac CT examinations. Using dose length product (DLP) for the same scans, we obtained values of E/DLP for three CT scanners used in cardiac imaging from two vendors. E/DLP ratios were obtained as a function of the anatomical location in the chest and for x-ray tube voltages ranging from 80 to 140 kV. We also computed the ratio of the average absorbed dose in a water cylinder modeling a patient weighing W kg to the corresponding average absorbed dose in a water cylinder equivalent to a 70 kg patient. The average E/DLP for a 16 cm cardiac heart CT scan was 26 microSv (mGy cm)(-1), which is about 70% higher than the current E/DLP values used for chest CT scans (i.e. 14-17 microSv (mGy cm)(-1)). Our cardiac E/DLP ratios are higher because the cardiac region is approximately 30% more radiosensitive than the chest, and use of the ICRP 103 tissue weighting factors increases cardiac CT effective doses by approximately 30%. Increasing the x-ray tube voltage from 80 to 140 kV increases the E/DLP conversion factor for cardiac CT by 17%. For the same incident radiation at 120 kV, doses in 45 kg adults were approximately 22% higher than those in 70 kg adults, whereas doses in 120 kg adults were approximately 28% lower. Accurate estimates of the patient effective dose in cardiac CT should use ICRP 103 tissue weighting factors, and account for a choice of scan techniques (kV mAs(-1)), exposed scan region, as well as patient size.