Assessing Different Chronic Wasting Disease Training Aids for Use with Detection Dogs.

Chronic wasting disease (CWD) is a highly infectious, fatal prion disease that affects cervid species. One promising method for CWD surveillance is the use of detection dog-handler teams wherein dogs are trained on the volatile organic compound signature of CWD fecal matter. However, using fecal matter from CWD-positive deer poses a biohazard risk; CWD prions can bind to soil particles and remain infectious in contaminated areas for extended periods of time, and it is very difficult to decontaminate the affected areas. One solution is to use noninfectious training aids that can replicate the odor of fecal matter from CWD-positive and CWD-negative deer and are safe to use in the environment. Trained CWD detection dogs' sensitivity and specificity for different training aid materials (cotton, GetXent tubes, and polydimethylsiloxane, or PDMS) incubated with fecal matter from CWD-positive and CWD-negative deer at two different temperatures (21 °C and 37 °C) for three different lengths of time (6 h, 24 h, and 48 h) were evaluated. Cotton incubated at 21 °C for 24 h was identified as the best aid for CWD based on the dogs' performance and practical needs for training aid creation. Implications for CWD detection training and for training aid selection in general are discussed.

A feasibility study of a deuterium-deuterium neutron generator-based boron neutron capture therapy system for treatment of brain tumors.

PURPOSE: Boron neutron capture therapy (BNCT) is a binary treatment modality that uses high LET particles to achieve tumor cell killing. Deuterium-deuterium (DD) compact neutron generators have advantages over nuclear reactors and large accelerators as the BNCT neutron source, such as their compact size, low cost, and relatively easy installation. The purpose of this study is to design a beam shaping assembly (BSA) for a DD neutron generator and assess the potential of a DD-based BNCT system using Monte Carlo (MC) simulations. METHODS: The MC model consisted of a head phantom, a DD neutron source, and a BSA. The head phantom had tally cylinders along the centerline for computing neutron and photon fluences and calculating the dose as a function of depth. The head phantom was placed at 4 cm from the BSA. The neutron source was modeled to resemble the source of our current DD neutron generator. A BSA was designed to moderate and shape the 2.45-MeV DD neutrons to the epithermal (0.5 eV to 10 keV) range. The BSA had multiple components, including moderator, reflector, collimator, and filter. Various materials and configurations were tested for each component. Each BSA layout was assessed in terms of the in-air and in-phantom parameters. The maximum brain dose was limited to 12.5 Gray-Equivalent (Gy-Eq) and the skin dose to 18 Gy-Eq. RESULTS: The optimized BSA configuration included 30 cm of lead for reflector, 45 cm of LiF, and 10 cm of MgF2 for moderator, 10 cm of lead for collimator, and 0.1 mm of cadmium for thermal neutron filter. Epithermal flux at the beam aperture was 1.0 × 105  nepi /cm2 -s; thermal-to-epithermal neutron ratio was 0.05; fast neutron dose per epithermal was 5.5 × 10-13  Gy-cm2 /φepi , and photon dose per epithermal was 2.4 × 10-13  Gy-cm2 /φepi . The AD, AR, and the advantage depth dose rate were 12.1 cm, 3.7, and 3.2 × 10-3  cGy-Eq/min, respectively. The maximum skin dose was 0.56 Gy-Eq. The DD neutron yield that is needed to irradiate in reasonable time was 4.9 × 1013  n/s. CONCLUSIONS: Results demonstrated that a DD-based BNCT system could be designed to produce neutron beams that have acceptable in-air and in-phantom characteristics. The parameter values were comparable to those of existing BNCT facilities. Continuing efforts are ongoing to improve the DD neutron yield.

Block Copolymer-Encapsulated CaWO4 Nanoparticles: Synthesis, Formulation, and Characterization.

We envision that CaWO4 (CWO) nanocrystals have the potential for use in biomedical imaging and therapy because of the unique ways this material interacts with high-energy radiation. These applications, however, require development of nanoparticle (NP) formulations that are suitable for in vivo applications; primarily, the formulated nanoparticles should be sufficiently small, chemically and biologically inert, and stable against aggregation under physiological conditions. The present study demonstrates one such method of formulation, in which CWO nanoparticles are encapsulated in bioinert block copolymer (BCP) micelles. For this demonstration, we prepared three different CWO nanocrystal samples having different sizes (3, 10, and 70 nm in diameter) and shapes (elongated vs truncated rhombic). Depending on the specific synthesis method used, the as-synthesized CWO NPs contain different surfactant materials (citric acid or cetyltrimethylammonium bromide or a mixture of oleic acid and oleylamine) in the coating layers. Regardless of the type of surfactant, the original surfactant coating can be replaced with a new enclosure formed by BCP materials using a solvent-exchange method. Two types of BCPs have been tested: poly(ethylene glycol-block-n-butyl acrylate) (PEG-PnBA) and poly(ethylene glycol-block-D,L-lactic acid) (PEG-PLA). Both BCPs are able to produce fully PEGylated CWO NPs that are stable against aggregation under physiological salt conditions for very long periods of time (at least three months). The optical and radio luminescence properties of both BCP-encapsulated and surfactant-coated CWO NPs were extensively characterized. The study confirms that the BCP coating structure does not influence the luminescence properties of CWO NPs.

IMAGING DIAGNOSIS-NUCLEAR SCINTIGRAPHIC, RADIOLOGICAL, AND PATHOLOGIC CHARACTERISTICS OF METASTATIC PILOMATRICOMA IN A DOG.

A 6-year-old castrated Goldendoodle dog was presented for left-sided lameness of 3 weeks' duration. Focal, moderate to marked increased 99m Tc-methylene diphosphonate (99m Tc-MDP) uptake was detected in the right caudal lung lobe, caudal angle of the left scapula, and the distal aspect of the left femur with whole body bone phase scintigraphy. Radiographs identified a well-circumscribed, oval-shaped soft tissue opaque mass in the right caudal lung lobe; a suspect oval-shaped osteolytic lesion in the proximal third of the left scapula; and an osteolytic lesion in the distal aspect of the left femur. Metastatic pilomatricoma was confirmed histologically at all three sites.

RADIATION THERAPY COMMUNICATION-REIRRADIATION OF A NASAL TUMOR IN A BRACHYCEPHALIC DOG USING INTENSITY MODULATED RADIATION THERAPY.

A 5-year-old spayed female Shih Tzu was referred for evaluation of a nasal transitional carcinoma. A total lifetime dose of 117 Gy was delivered to the intranasal mass in three courses over nearly 2 years using fractionated intensity modulated radiation therapy (IMRT) to spare normal tissues. Clinically significant late normal tissue side effects were limited to bilaterally diminished tear production. The patient died of metastatic disease progression 694 days after completion of radiation therapy course 1. This case demonstrates that retreatment with radiation therapy to high lifetime doses for recurrent local disease may be well tolerated with IMRT.

Ionizing radiation induces neuroendocrine differentiation of prostate cancer cells in vitro, in vivo and in prostate cancer patients.

Prostate cancer remains the most common noncutaneous cancer among American men. Although most patients can be cured by surgery and radiotherapy, 32,050 patients still died of the disease in 2010. Many patients receive radiotherapy either as a primary therapy, salvage therapy, or in combination with surgery or hormonal therapy. Despite initial treatment, several studies suggest that approximately 10% of low-risk prostate cancer patients and up to 30-60% with more advanced cancer patients experience biochemical recurrence within five years after radiotherapy. Thus, elucidating the molecular mechanisms underlying radioresistance and tumor recurrence has the potential to significantly reduce prostate cancer mortality. We previously demonstrated that fractionated ionizing radiation (IR) can induce the prostate cancer cell line LNCaP to undergo neuroendocrine differentiation (NED) by activation of cAMP response element binding protein (CREB) and cytoplasmic sequestration of ATF2, two CRE-binding transcription factors that oppose each other to regulate NED. Importantly, IR-induced NED is reversible and de-differentiated cells are cross-resistant to IR, androgen depletion and docetaxel treatments. These findings suggest that radiation-induced NED may allow prostate cancer cells to survive treatment and contribute to tumor recurrence. In the present study, we further demonstrated that IR also induces NED in a subset of DU-145 and PC-3 cells. In addition, we confirmed that IR induces NED in LNCaP xenograft tumors in nude mice, and observed that the plasma chro-mogranin A (CgA) level, a biomarker for NED, is increased by 2- to 5-fold in tumor-bearing mice after fractionated radiation doses of 20 and 40 Gy, respectively. Consistent with these in vivo findings, a pilot study in prostate cancer patients showed that the serum CgA level is elevated in 4 out of 9 patients after radiotherapy. Taken together, these findings provide evidence that radiation-induced NED is a general therapeutic response in a subset of prostate cancer patients. Thus, a large scale analysis of radiotherapy-induced NED in prostate cancer patients and its correlation to clinical outcomes will likely provide new insight into the role of NED in prostate cancer radiotherapy and prognosis.

Use of force plate analysis to evaluate the efficacy of external beam radiation to alleviate osteosarcoma pain.

A standard of therapy for osteosarcoma includes amputation with or without adjuvant chemotherapy. There is a subset of dogs with osteosarcoma that are unsuitable for amputation. We evaluated kinetic variables in dogs with appendicular osteosarcoma treated with a single 8 Gy dose of radiation. Eighteen pet dogs with appendicular osteosarcoma received one 8 Gy fraction of palliative radiation on day 0. Force plate measurements and clinical assessments were made on days 0, 7, 14, and 21. Peak vertical forces (Fz) were recorded for each limb and a symmetric index (SI) was calculated. There were no significant changes in kinetic parameters after one 8 Gy dose of radiation therapy. Nine of these 18 dogs exhibited increased limb function at day 21 based on force plate analysis. Significant factors affecting Fz included gender and tumor location. There was a significant correlation between Fz and response to therapy based on SI at day 21. SI seems to be useful to objectively assess response in this mixed population of dogs. One 8 Gy fraction of radiation therapy alone did not reduce lameness associated with appendicular osteosarcoma, but a subset of dogs did have improved limb function after a single dose.

Osteoradionecrosis and radiation induced bone tumors following orthovoltage radiation therapy in dogs.

Osteoradionecrosis and radiation-induced bone tumors are rare complications of radiation therapy. Little information regarding these complications is available in veterinary medicine. We characterized these complications and investigated risk factors in 119 dogs (122 sites) that received definitive orthovoltage radiation therapy to appendicular sites. Long-term survival was expected in all dogs. The complications of interest were osteoradionecrosis and secondary bone tumor, evaluated radiographically, histopathologically, or both. Complication rates were estimated using the Kaplan-Meier product-limit method, and Fisher's exact test or chi-square test was used to compare the complication rate. The median survival time was 1405 days, with median follow-up duration of 657 days. There were 10 radiation-induced bone tumors and five radiation-induced fractures, with two dogs developing both, for an overall complication rate of 11%. The latent period ranged from 1.2 to 6.4 years for osteoradionecrosis and from 2.6 to 8.7 years for radiation-induced bone tumor. Complications were significantly higher in the humerus (P < 0.0001), and in dogs younger than 7 years (P = 0.014). Similar assessment of complications in dogs irradiated with megavoltage photons or electrons are needed.

A phase I trial of hyperthermia-induced interleukin-12 gene therapy in spontaneously arising feline soft tissue sarcomas.

Interleukin-12 (IL-12), a proinflammatory cytokine, shows anticancer properties. Systemically administered IL-12 causes dose-dependent toxicity. To achieve localized intratumoral gene expression, an adenoviral gene therapy vector with IL-12 controlled by a heat-inducible promoter (heat shock promoter 70B) was developed and tested in a phase I clinical trial in cats with spontaneously arising soft tissue sarcoma. A feasibility study was done in 16 cats with soft tissue sarcoma using murine IL-12 and/or enhanced green fluorescent protein adenoviral vectors under cytomegalovirus or heat shock promoter 70 control. Subsequently, we conducted a phase I clinical trial using an adenoviral feline IL-12 construct in 13 cats with soft tissue sarcoma. The soft tissue sarcomas were irradiated (48 Gy/16 fractions) followed by intratumoral injection of adenovirus. Twenty-four hours postinjection, tumors were heated (41 degrees C, 60 min). Tumor expression of feline IL-12 and IFN-gamma was determined. Cats were monitored for systemic toxicity. For the murine IL-12 construct, an association was noted between viral dose and murine IL-12 levels within tumor, whereas serum levels were minimal. Mild toxicity was noted at 10(11) plaque-forming units (pfu). With the feline IL-12 construct, high levels of feline IL-12 mRNA were detected in tumor biopsies with low or absent IFN-gamma mRNA following gene therapy. Hematologic and hepatic toxicities were noted at the highest viral doses and were associated with detection of IFN-gamma mRNA in tumor. It is possible to localize gene expression and limit systemic toxicity of IL-12 using the hyperthermia-induced gene therapy approach. The maximum tolerated dose of the feline IL-12 adenoviral vector was 10(10) pfu/tumor as dose-limiting toxicities were noted at the 4 x 10(10) pfu dose.

Extracellular pH and P-31 magnetic resonance spectroscopic variables are related to outcome in canine soft tissue sarcomas treated with thermoradiotherapy.

PURPOSE: The objective was to test whether tumor pH and (31)P magnetic resonance spectroscopic end points were related to treatment outcome in pet canine patients with spontaneous soft tissue sarcomas treated with thermoradiotherapy. EXPERIMENTAL DESIGN: Forty-two dogs with evaluable (31)P magnetic resonance spectroscopic end points and pH data were included in this study. Tumor variables (grade and volume), extracellular pH (pHe), T(2) relaxation times, intracellular pH, and selected phosphometabolite ratios were examined for correlation with clinical outcome. RESULTS: From 39 dogs, pHe was a predictor of metastasis-free survival (MFS), with hazard ratio (HR, 0.29; P = 0.005) and overall survival (OS) with (HR, 0.36; P = 0.013). Tumor volume (>19 cm(3)) was related to MFS (HR, 2.14; P = 0.04), time to local failure (HR, 3.4; P = 0.025), and OS (HR, 2.27; P = 0.03). There was no association between T(2) or intracellular pH and clinical outcome. Tumor grade (high versus low/intermediate) and phosphodiester/betaATP ratio were identified as significant predictors for MFS, with (HR, 2.66; P = 0.009) and (HR, 0.75; P = 0.027), respectively, and as predictors of OS with (HR, 2.66; P = 0.009) and (HR, 0.76; P = 0.03), respectively. The phosphodiester/phosphocreatinine ratio predicted time to local failure (HR, 1.24; P = 0.017). CONCLUSIONS: pHe was predictive of metastasis and OS in canine spontaneous sarcomas. To our knowledge, this is the first time that pHe has been shown to be predictive of clinical outcome. The results suggest that additional studies should be considered evaluating the prognostic significance of this variable. Phospholipid resonances, related to membrane metabolism, were related to clinical outcome, confirming recent results reported in human patients with soft tissue sarcomas treated with thermoradiotherapy.

Phase I trial of doxorubicin-containing low temperature sensitive liposomes in spontaneous canine tumors.

PURPOSE: To determine the maximum tolerated dose, dose-limiting toxicities, and pharmacokinetic characteristics of doxorubicin encapsulated in a low temperature sensitive liposome (LTSL) when given concurrently with local hyperthermia to canine solid tumors. EXPERIMENTAL DESIGN: Privately owned dogs with solid tumors (carcinomas or sarcomas) were treated. The tumors did not involve bone and were located at sites amenable to local hyperthermia. LTSL-doxorubicin was given (0.7-1.0 mg/kg i.v.) over 30 minutes during local tumor hyperthermia in a standard phase I dose escalation study. Three treatments, given 3 weeks apart, were scheduled. Toxicity was monitored for an additional month. Pharmacokinetics were evaluated during the first treatment cycle. RESULTS: Twenty-one patients were enrolled: 18 with sarcomas and 3 with carcinomas. Grade 4 neutropenia and acute death secondary to liver failure, possibly drug related, were the dose-limiting toxicities. The maximum tolerated dose was 0.93 mg/kg. Other toxicities, with the possible exception of renal damage, were consistent with those observed following free doxorubicin administration. Of the 20 dogs that received > or = 2 doses of LTSL-doxorubicin, 12 had stable disease, and 6 had a partial response to treatment. Pharmacokinetic variables were more similar to those of free doxorubicin than the marketed liposomal product. Tumor drug concentrations at a dose of 1.0 mg/kg averaged 9.12 +/- 6.17 ng/mg tissue. CONCLUSION: LTSL-doxorubicin offers a novel approach to improving drug delivery to solid tumors. It was well tolerated and resulted in favorable response profiles in these patients. Additional evaluation in human patients is warranted.

Relation between pO2, 31P magnetic resonance spectroscopy parameters and treatment outcome in patients with high-grade soft tissue sarcomas treated with thermoradiotherapy.

PURPOSE: In a prior study, the combination of (31)P magnetic resonance spectroscopy (MRS)-based intracellular pH (pHi) and T2 relaxation time was highly predictive of the pathologic complete response (pCR) rate in a small series of patients with soft tissue sarcomas (STSs) treated with thermoradiotherapy. Changes in the magnetic resonance metabolite ratios and pO(2) were related to the pCR rate. Hypoxia also correlated with a greater likelihood for the development of metastases. Because of the limited number of patients in the prior series, we initiated this study to determine whether the prior observations were repeatable and whether (31)P MRS lipid-related resonances were related to a propensity for metastasis. METHODS AND MATERIALS: Patients with high-grade STSs were enrolled in an institutional review board-approved Phase II thermoradiotherapy trial. All tumors received daily external beam radiotherapy (1.8-2.0 Gy, five times weekly) to a total dose of 30-50 Gy. Hyperthermia followed radiotherapy by <1 h and was given two times weekly. Tumors were resected 4-6 weeks after radiotherapy completion. The MRS/MRI parameters included (31)P metabolite ratios, pHi, and T2 relaxation time. The median pO(2) and hypoxic fraction were determined using pO(2) histography. Comparisons between experimental endpoints and the pCR rate and metastasis-free and overall survival were made. RESULTS: Of 35 patients, 21 and 28 had reportable pretreatment MRS/MRI and pO(2) data, respectively. The cutpoints for a previously tested receiver operating curve for a pCR were T2 = 100 and pHi = 7.3. In the current series, few tumors fell below the cutpoints so validation was not possible. The phosphodiester (PDE)/inorganic phosphate (Pi) ratio and hypoxic fraction correlated inversely with the pCR rate in the current series (Spearman correlation coefficient -0.51, p = 0.017; odds ratio of percentage of necrosis > or =95% = 0.01 for a 1% increase in the hypoxic fraction; Wald p = 0.036). The pretreatment phosphomonoester (PME)/Pi ratio also correlated inversely with the pCR rate (odds ratio of percentage of necrosis > or =95% = 0.06 for pretreatment PME/Pi ratio >0.8 vs. < or =0.8, Wald p = 0.023). The pretreatment PME/PDE ratio correlated strongly with metastasis-free survival and overall survival (p = 0.012 and hazard ratio = 5.8, and p = 0.038 and hazard ratio = 6.75, respectively). CONCLUSION: The dual parameter model containing pHi and T2 to predict the pCR in STSs treated with thermoradiotherapy was not verified. However, other parameters were statistically significant, including the PDE/Pi ratio and hypoxic fraction. These relationships may have interfered with our ability to obtain the pCR rate predicted by thermal doses achieved in these patients. The relationship between the PME/PDE ratio and metastasis-free and overall survival was provocative, but requires additional study to verify its predictive capability. Currently, 50% of all STS patients with high-grade tumors develop distant metastasis even when excellent local control is achieved. Parameters that could help select for patients who need adjuvant chemotherapy could have significant clinical benefit.