Subacute administration of both methcathinone and manganese causes basal ganglia damage in mice resembling that in methcathinone abusers.

An irreversible extrapyramidal syndrome occurs in man after intravenous abuse of "homemade" methcathinone (ephedrone, Mcat) that is contaminated with manganese (Mn) and is accompanied by altered basal ganglia function. Both Mcat and Mn can cause alterations in nigrostriatal function but it remains unknown whether the effects of the 'homemade' drug seen in man are due to Mcat or to Mn or to a combination of both. To determine how toxicity occurs, we have investigated the effects of 4-week intraperitoneal administration of Mn (30 mg/kg t.i.d) and Mcat (100 mg/kg t.i.d.) given alone, on the nigrostriatal function in male C57BL6 mice. The effects were compared to those of the 'homemade' mixture which contained about 7 mg/kg of Mn and 100 mg/kg of Mcat. Motor function, nigral dopaminergic cell number and markers of pre- and postsynaptic dopaminergic neuronal integrity including SPECT analysis were assessed. All three treatments had similar effects on motor behavior and neuronal markers. All decreased motor activity and induced tyrosine hydroxylase positive cell loss in the substantia nigra. All reduced 123I-epidepride binding to D2 receptors in the striatum. Vesicular monoamine transporter 2 (VMAT2) binding was not altered by any drug treatment. However, Mcat treatment alone decreased levels of the dopamine transporter (DAT) and Mn alone reduced GAD immunoreactivity in the striatum. These data suggest that both Mcat and Mn alone could contribute to the neuronal damage caused by the 'homemade' mixture but that both produce additional changes that contribute to the extrapyramidal syndrome seen in man.

Verapamil results in increased blood levels of oncolytic adenovirus in treatment of patients with advanced cancer.

Calcium channel blockers including verapamil have been proposed to enhance release and antitumor efficacy of oncolytic adenoviruses in preclinical studies but this has not been studied in humans before. Here, we studied if verapamil leads to increased replication of oncolytic adenovirus in cancer patients, as measured by release of virions from tumor cells into the systemic circulation. The study was conducted as a matched case-control study of advanced cancer patients treated with oncolytic adenoviruses with or without verapamil. We observed that verapamil increased mean virus titers present in blood after treatment (P < 0.05). The frequency or severity of adverse events was not increased, nor were cytokine responses or neutralizing antibody levels different between groups. Signs of possible treatment-related clinical benefits were observed in both groups, but there was no significant difference in responses or survival. Thus, our data suggests that the combination of verapamil with oncolytic adenoviruses is safe and well tolerated. Moreover, verapamil treatment seems to result in higher virus titers in blood, indicating enhanced overall replication in tumors. A randomized trial is needed to confirm these findings and to study if enhanced replication results in benefits to patients.

Integrin targeted oncolytic adenoviruses Ad5-D24-RGD and Ad5-RGD-D24-GMCSF for treatment of patients with advanced chemotherapy refractory solid tumors.

The safety of oncolytic viruses for treatment of cancer has been shown in clinical trials while antitumor efficacy has often remained modest. As expression of the coxsackie-adenovirus receptor may be variable in advanced tumors, we developed Ad5-D24-RGD, a p16/Rb pathway selective oncolytic adenovirus featuring RGD-4C modification of the fiber. This allows viral entry through alpha-v-beta integrins frequently highly expressed in advanced tumors. Advanced tumors are often immunosuppressive which results in lack of tumor eradication despite abnormal epitopes being present. Granulocyte-macrophage colony stimulating factor (GMCSF) is a potent activator of immune system with established antitumor properties. To stimulate antitumor immunity and break tumor associated immunotolerance, we constructed Ad5-RGD-D24-GMCSF, featuring GMCSF controlled by the adenoviral E3 promoter. Preliminary safety of Ad5-D24-RGD and Ad5-RGD-D24-GMCSF for treatment of human cancer was established. Treatments with Ad5-D24-RGD (N = 9) and Ad5-RGD-D24-GMCSF (N = 7) were well tolerated. Typical side effects were grade 1-2 fatigue, fever and injection site pain. 77% (10/13) of evaluable patients showed virus in circulation for at least 2 weeks. In 3 out of 6 evaluable patients, disease previously progressing stabilized after a single treatment with Ad5-RGD-D24-GMCSF. In addition, 2/3 patients had stabilization or reduction in tumor marker levels. All patients treated with Ad5-D24-RGD showed disease progression in radiological analysis, although 3/6 had temporary reduction or stabilization of marker levels. Induction of tumor and adenovirus specific immunity was demonstrated with ELISPOT in Ad5-RGD-D24-GMCSF treated patients. RGD modified oncolytic adenoviruses with or without GMCSF seem safe for further clinical development.

Induction of interferon pathways mediates in vivo resistance to oncolytic adenovirus.

Oncolytic adenoviruses are an emerging experimental approach for treatment of tumors refractory to available modalities. Although preclinical results have been promising, and clinical safety has been excellent, it is also apparent that tumors can become virus resistant. The resistance mechanisms acquired by advanced tumors against conventional therapies are increasingly well understood, which has allowed development of countermeasures. To study this in the context of oncolytic adenovirus, we developed two in vivo models of acquired resistance, where initially sensitive tumors eventually gain resistance and relapse. These models were used to investigate the phenomenon on RNA and protein levels using two types of analysis of microarray data, quantitative reverse transcriptase-polymerase chain reaction and immunohistochemistry. Interferon (IFN) signaling pathways were found upregulated and Myxovirus resistance protein A (MxA) expression was identified as a marker correlating with resistance, while transplantation experiments suggested a role for tumor stroma in maintaining resistance. Furthermore, pathway analysis suggested potential therapeutic targets in oncolytic adenovirus-resistant cells. Improved understanding of the antiviral phenotype causing tumor recurrence is of key importance in order to improve treatment of advanced tumors with oncolytic adenoviruses. Given the similarities between mechanisms of action, this finding might be relevant for other oncolytic viruses as well.

Switching the fiber knob of oncolytic adenoviruses to avoid neutralizing antibodies in human cancer patients.

BACKGROUND: Oncolytic adenoviruses are an attractive strategy for treating cancers resistant to conventional treatments. However, their systemic utility could be limited as a result of the high prevalence of pre-existing immunity towards the vector. Furthermore, neutralizing antibodies (NAbs) may prevent successful intravenous readministration of the same agent. Previous preclinical reports indicate that the NAb response can be partially overcome by modifying the adenoviral fiber knob. However, to date, this strategy has not been evaluated in human patients. METHODS: Twenty-four human patients with advanced cancer were treated with two cycles of oncolytic adenoviruses, featuring three capsid variants: unmodified adenovirus serotype 5 (Ad5), serotype 5 with RGD motif in the HI-loop of the fiber knob (Ad5-RGD) and serotype 5 carrying fiber knob from serotype 3 (Ad5/3). A virus with different fiber structure was used for the second round of treatment and patient serum was analyzed for a neutralizing effect. RESULTS: All patients developed NAbs against the virus that they were treated with. However, the magnitude and velocity of the response varied considerably. When measured just before the second treatment cycle, a differential in serum NAb titer against the first versus second virus was seen in 83% of cases, suggesting that even minor changes in the fiber knob can circumvent neutralization in cancer patients. No correlation between NAb titers and outcome variables was observed. CONCLUSIONS: The results obtained in the present study extend previous preclinical reports into human cancer patients and suggest that modification of the fiber knob is a feasible strategy for circumventing the NAb response in patients receiving multiple rounds of oncolytic adenoviruses.

Safety of glucocorticoids in cancer patients treated with oncolytic adenoviruses.

Oncolytic adenoviruses are an emerging treatment option for advanced and refractory cancer. Such patients are often treated with corticosteroids to ameliorate tumor associated symptoms. Thus, it is important to evaluate whether safety is affected by immunosuppression possibly induced by corticosteroids. Concurrent low-dose cyclophosphamide, appealing for its immunomodulatory effects, could also impact safety. In a retrospective case-control study, we evaluated the effect of systemic corticosteroid use in cancer patients receiving oncolytic virotherapy. Four treatment groups were identified: (1) oncolytic adenovirus with oral glucocorticoids, (2) virus alone, (3) virus with glucocorticoids and cyclophosphamide and (4) virus with cyclophosphamide. Adverse events, neutralizing antibody titers, viral DNA in circulation and tumor responses were evaluated. The most common adverse effects were grade 1-2 fatigue, nausea, fever and abdominal pain. Common asymptomatic findings included self-limiting grade 1-3 hyponatremia and aspartate aminotransferase increase. Safety was good and no significant differences were observed between the groups. All patients had an increase in neutralizing antibody titers post-treatment, and no trends for differences between groups were observed. There were fewer post-treatment virus genomes circulating in patients receiving glucocorticoids when compared to their control groups. Overall, glucocorticoid use in cancer patients receiving oncolytic adenovirus, with or without low-dose cyclophosphamide, seems safe.

Treatment of cancer patients with a serotype 5/3 chimeric oncolytic adenovirus expressing GMCSF.

Augmenting antitumor immunity is a promising way to enhance the potency of oncolytic adenoviral therapy. Granulocyte-macrophage colony-stimulating factor (GMCSF) can mediate antitumor effects by recruiting natural killer cells and by induction of tumor-specific CD8(+) cytotoxic T-lymphocytes. Serotype 5 adenoviruses (Ad5) are commonly used in cancer gene therapy. However, expression of the coxsackie-adenovirus receptor is variable in many advanced tumors and preclinical data have demonstrated an advantage for replacing the Ad5 knob with the Ad3 knob. Here, a 5/3 capsid chimeric and p16-Rb pathway selective oncolytic adenovirus coding for GMCSF was engineered and tested preclinically. A total of 21 patients with advanced solid tumors refractory to standard therapies were then treated intratumorally and intravenously with Ad5/3-D24-GMCSF, which was combined with low-dose metronomic cyclophosphamide to reduce regulatory T cells. No severe adverse events occurred. Analysis of pretreatment samples of malignant pleural effusion and ascites confirmed the efficacy of Ad5/3-D24-GMCSF in transduction and cell killing. Evidence of biological activity of the virus was seen in 13/21 patients and 8/12 showed objective clinical benefit as evaluated by radiology with Response Evaluation Criteria In Solid Tumors (RECIST) criteria. Antiadenoviral and antitumoral immune responses were elicited after treatment. Thus, Ad5/3-D24-GMCSF seems safe in treating cancer patients and promising signs of efficacy were seen.

Oncolytic adenovirus Ad5/3-delta24 and chemotherapy for treatment of orthotopic ovarian cancer.

OBJECTIVE: Oncolytic adenoviruses capable of replication selectively in tumor cells are an appealing approach for the treatment of neoplastic diseases refractory to conventional therapies. The aim of this study was to evaluate the effect of dose and scheduling of a tropism-modified, adenovirus serotype 3 receptor-targeted, Rb/p16 pathway-selective replication-competent adenovirus, Ad5/3-delta24, against human ovarian adenocarcinoma. As oncolytic viruses and chemotherapy can have synergistic interactions, the antitumor efficacy of Ad5/3-delta24 was also studied in combination with epirubicin and gemcitabine, common second-line treatment options for platinum-resistant ovarian cancer. METHODS: Orthotopic murine models of peritoneally disseminated ovarian cancer were utilized to compare survival of mice treated with either a single viral dose or weekly delivery. The lowest effective dose of intraperitoneal Ad5/3-delta24 was determined. Combinations of Ad5/3-delta24 and gemcitabine or epirubicin were studied in vitro as well as in vivo. RESULTS: Treatment outcome after administration of a single dose of Ad5/3-delta24 was as effective as delivery of several weekly doses. Our results also demonstrate that a single intraperitoneal injection of 100 viral particles significantly increased the survival of mice compared to untreated animals. Further, combining Ad5/3-delta24 with either gemcitabine or epirubicin resulted in greater therapeutic benefit than either agent alone. CONCLUSION: These preclinical data suggest that Ad5/3-delta24 represents a promising treatment strategy for advanced ovarian cancer as a single agent or in combination with chemotherapy.

Infectivity-enhanced adenoviruses deliver efficacy in clinical samples and orthotopic models of disseminated gastric cancer.

PURPOSE: Metastatic gastric cancer remains a common and devastating disease without curative treatment. Recent proof-of-concept clinical trials have validated gene therapy with adenoviruses as an effective and safe modality for the treatment of cancer. However, expression of the primary coxsackie-adenovirus receptor is variable in advanced cancers, and therefore, the use of heterologous receptors could be advantageous. EXPERIMENTAL DESIGN: Here, we used capsid-modified adenoviruses for increasing the transduction and subsequent antitumor efficacy. 5/3 chimeric viruses have a serotype 3 knob which allows binding to a receptor distinct from coxsackie-adenovirus receptor. The fiber of Ad5lucRGD is modified with an integrin-targeted motif. Polylysine motifs, pK7 and pK21, bind to heparan sulfates. Oncolytic adenoviruses replicate in and kill tumor cells selectively. Gastric cancer cell lines and fresh clinical samples from patients were infected with transductionally targeted viruses. Capsid-modified oncolytic adenoviruses were used in cell killing experiments. To test viral transduction and therapeutic efficacy in vivo, we developed orthotopic mouse models featuring i.p. disseminated human gastric cancer, which allowed the evaluation of biodistribution and antitumor efficacy in a system similar to humans. RESULTS: Capsid modifications benefited gene transfer efficiency and cell killing in gastric cancer cell lines and clinical samples in vitro and in vivo. Modified oncolytic adenoviruses significantly increased the survival of mice with orthotopic gastric cancer. CONCLUSIONS: These preclinical data set the stage for the clinical evaluation of safety and efficacy in patients with disease refractory to current modalities.

Differential Clearance of Rat and Human Bone Marrow-Derived Mesenchymal Stem Cells From the Brain After Intra-arterial Infusion in Rats.

Intra-arterial (IA) delivery of bone marrow-derived mesenchymal stem cells (BM-MSCs) has shown potential as a minimally invasive therapeutic approach for stroke. The aim of the present study was to determine the whole-body biodistribution and clearance of technetium-99m ((99m)Tc)-labeled rat and human BM-MSCs after IA delivery in a rat model of transient middle cerebral artery occlusion (MCAO) using single-photon emission computed tomography (SPECT). Our hypothesis was that xenotransplantation has a major impact on the behavior of cells. Male RccHan:Wistar rats were subjected to sham operation or MCAO. Twenty-four hours after surgery, BM-MSCs (2 × 10(6) cells/animal) labeled with (99m)Tc were infused into the external carotid artery. Whole-body SPECT images were acquired 20 min, 3 h, and 6 h postinjection, after which rats were sacrificed, and organs were collected and weighed for measurement of radioactivity. The results showed that the majority of the cells were located in the brain and especially in the ipsilateral hemisphere immediately after cell infusion both in sham-operated and MCAO rats. This was followed by fast disappearance, particularly in the case of human cells. At the same time, the radioactivity signal increased in the spleen, kidney, and liver, the organs responsible for destroying cells. Further studies are needed to demonstrate whether differential cell behavior has any functional impact.

Technetium-99m-labeled nanofibrillar cellulose hydrogel for in vivo drug release.

Nanoscale celluloses have recently gained an increasing interest in modern medicine. In this study, we investigated the properties of plant derived nanofibrillar cellulose (NFC) as an injectable drug releasing hydrogel in vivo. We demonstrated a reliable and efficient method of technetium-99m-NFC labeling, which enables us to trace the in vivo localization of the hydrogel. The release and distribution of study compounds from the NFC hydrogel after subcutaneous injection in the pelvic region of BALB/c mice were examined with a multimodality imaging device SPECT/CT. The drug release profiles were simulated by 1-compartmental models of Phoenix® WinNonlin®. The NFC hydrogel remained intact at the injection site during the study. The study compounds are more concentrated at the injection site when administered with the NFC hydrogel compared with saline solutions. In addition, the NFC hydrogel reduced the elimination rate of a large compound, technetium-99m-labeled human serum albumin by 2 folds, but did not alter the release rate of a small compound (123)I-ß-CIT (a cocaine analogue). In conclusion, the NFC hydrogels is easily prepared and readily injected, and it has potential use as a matrix for controlled release or local delivery of large compounds. The interactions between NFC and specific therapeutic compounds are possible and should be investigated further.

Synthesis and biological evaluation of novel (123)I-labeled 4-(4-iodophenyl)butanoyl-L-prolyl-(2S)-pyrrolidines for imaging prolyl oligopeptidase in vivo.

Prolyl oligopeptidase (POP) may be associated with neuromodulation and development of neurodegenerative diseases and it was recently shown to participate in the inflammatory cascade along with matrix metalloproteinases. Radiotracers, which can be used for non-invasive imaging, are needed for investigating the role of POP in normal physiology and in pathophysiological conditions in vivo. We synthesized two novel POP-specific (123)I-radiolabeled 4-phenylbutanoyl-L-prolyl-pyrrolidines of which 4-(4-[(123)I]iodophenyl)butanoyl-L-prolyl-2(S)-cyanopyrrolidine ([(123)I]2f, Ki = 4.2 nM) was selected. The selected compound has an electrophilic cyano group that is known to increase the dissociation time of POP inhibitors. [(123)I]2f was synthesized in high radiochemical yield and purity (87 ± 4%, >99%, respectively) and with a specific activity of 456 ± 98 GBq/µmol. [(123)I]2f was evaluated in healthy mice (C57Bl/6JRccHsd) by ex vivo biodistribution studies and SPECT imaging. Pretreatment with the known inhibitor 4-phenylbutanoyl-L-prolyl-(2S)-cyanopyrrolidine (KYP-2047, 2d, Ki = 0.023 nM) showed that binding of [(123)I]2f was POP specific. In addition, [(123)I]2f was evaluated in models of neuroinflammation and acute localized inflammation. A minor increase in binding of [(123)I]2f was observed in the inflamed region in the acute localized inflammation model. Similar increase in binding was not observed in the neuroinflammation model.

Radiolabeled peptides for Alzheimer's diagnostic imaging: mini review.

The pathology of Alzheimer's disease (AD) is characterized by the extracellular and intracellular accumulation of amyloid-ß (Aß) fibrillar plaques formed by the Aß1-42 peptide, neurofibrillary tangles (NFTs) consisting of hyperphosphorylated tau, extensive neuritic and synaptic degradation, and neuron loss. One of the priorities for the treatment of AD is both the early detection and accurate chart progression of the accumulation of Aß plaques in human brains. Molecular imaging tools can provide an in vivo visualization of Aß plaques. Specific identification of amyloid plaques would allow a more accurate prognosis and ensure more effective clinical trials of anti-amyloid agents at earlier disease stage. The emphasis of this review is on the development of Aß peptide radiopharmaceuticals or the ones combined with nanocarrier-based such as Molecular Trojan horses or nanoparticles for applications in in vivo amyloid imaging in AD.

High correlation between in vivo [123I]ß-CIT SPECT/CT imaging and post-mortem immunohistochemical findings in the evaluation of lesions induced by 6-OHDA in rats.

BACKGROUND: 6-Hydroxydopamine (6-OHDA) is widely used in pre-clinical animal studies to induce degeneration of midbrain dopamine neurons to create animal models of Parkinson's disease. The aim of our study was to evaluate the potential of combined single-photon emission computed tomography/computed tomography (SPECT/CT) for the detection of differences in 6-OHDA-induced partial lesions in a dose- and time-dependent manner using the dopamine transporter (DAT) ligand 2ß-carbomethoxy-3ß-(4-[123I]iodophenyl)tropane ([123I]ß-CIT). METHODS: Rats were unilaterally lesioned with intrastriatal injections of 8 or 2 × 10 µg 6-OHDA. At 2 or 4 weeks post-lesion, 40 to 50 MBq [123I]ß-CIT was administered intravenously and rats were imaged with small-animal SPECT/CT under isoflurane anesthesia. The striatum was delineated and mean striatal activity in the lesioned side was compared to the intact side. After the [123I]ß-CIT SPECT/CT scan, the rats were tested for amphetamine-induced rotation asymmetry, and their brains were immunohistochemically stained for DAT and tyrosine hydroxylase (TH). The fiber density of DAT- and TH-stained striata was estimated, and TH-immunoreactive cells in the rat substantia nigra pars compacta (SNpc) were stereologically counted. RESULTS: The striatal uptake of [123I]ß-CIT differed significantly between the lesion groups and the results were highly correlated to both striatal DAT- and TH-immunoreactive fiber densities and to TH-immunoreactive cell numbers in the rat SNpc. No clear progression of the lesion could be seen. CONCLUSIONS: [123I]ß-CIT SPECT/CT is a valuable tool in predicting the condition of the rat midbrain dopaminergic pathway in the unilateral partial 6-OHDA lesion model of Parkinson's disease and it offers many advantages, allowing repeated non-invasive analysis of living animals.

Transient proteolytic modification of mesenchymal stromal cells increases lung clearance rate and targeting to injured tissue.

Systemic infusion of therapeutic cells would be the most practical and least invasive method of administration in many cellular therapies. One of the main obstacles especially in intravenous delivery of cells is a massive cell retention in the lungs, which impairs homing to the target tissue and may decrease the therapeutic outcome. In this study we showed that an alternative cell detachment of mesenchymal stromal/stem cells (MSCs) with pronase instead of trypsin significantly accelerated the lung clearance of the cells and, importantly, increased their targeting to an area of injury. Cell detachment with pronase transiently altered the MSC surface protein profile without compromising cell viability, multipotent cell characteristics, or immunomodulative and angiogenic potential. The transient modification of the cell surface protein profile was sufficient to produce effective changes in cell rolling behavior in vitro and, importantly, in the in vivo biodistribution of the cells in mouse, rat, and porcine models. In conclusion, pronase detachment could be used as a method to improve the MSC lung clearance and targeting in vivo. This may have a major impact on the bioavailability of MSCs in future therapeutic regimes.

SPECT/CT imaging of radiolabeled cubosomes and hexosomes for potential theranostic applications.

We have developed a highly efficient method for the radiolabeling of phytantriol (PHYT)/oleic acid (OA)-based hexosomes based on the surface chelation of technetium-99m ((99m)Tc) to preformed hexosomes using the polyamine 1, 12-diamino-3, 6, 9-triazododecane (SpmTrien) as chelating agent. We also report on the unsuccessful labeling of cubosomes using the well-known chelating agent hexamethylpropyleneamine oxime (HMPAO). The (99m)Tc-labeled SpmTrien-hexosomes ((99m)Tc-SpmTrien-hexosomes) were synthesized with good radiolabeling (84%) and high radiochemical purity (>90%). The effect of radiolabeling on the internal nanostructure and the overall size of these aqueous dispersions was investigated by using synchrotron small angle X-ray scattering (SAXS), dynamic light scattering (DLS), and transmission electron cryo microscopy (cryo-TEM). Further, we show the utility of (99m)Tc-SpmTrien-hexosomes for the in vivo imaging of healthy mice using single photon emission computed tomography (SPECT) in combination with computed tomography (CT), i.e. SPECT/CT. SPECT/CT experiments of subcutaneously administered (99m)Tc-SpmTrien-hexosomes to the flank of mice showed a high stability in vivo allowing imaging of the distribution of the radiolabeled hexosomes for up to 24 h. These injected (99m)Tc-SpmTrien-hexosomes formed a deposit within the subcutaneous adipose tissue, displaying a high biodistribution of ≈ 343% injected dose/g tissue (%ID/g), with negligible uptake in other organs and tissues. The developed (99m)Tc labeling method for PHYT/OA-based hexosomes could further serve as a useful tool for investigating and imaging the in vivo performance of cubosomal and hexosomal drug nanocarriers.

Advanced brain dopamine transporter imaging in mice using small-animal SPECT/CT.

BACKGROUND: Iodine-123-ß-CIT, a single-photon emission computed tomography (SPECT) ligand for dopamine transporters (DATs), has been used for in vivo studies in humans, monkeys, and rats but has not yet been used extensively in mice. To validate the imaging and analysis methods for preclinical DAT imaging, wild-type healthy mice were scanned using 123I-ß-CIT. METHODS: The pharmacokinetics and reliability of 123I-ß-CIT in mice (n = 8) were studied with a multipinhole SPECT/CT camera after intravenous injection of 123I-ß-CIT (38 ± 3 MBq). Kinetic imaging of three mice was continued for 7 h postinjection to obtain the time-activity curves in the striatum and cerebellum volumes. Five mice had repeated measures 4 h post-123I-ß-CIT injection to provide an indication of test-retest reliability. The same five mice served as a basis for a healthy mean SPECT template. RESULTS: Specific binding of 123I-ß-CIT within the mouse striatum could be clearly visualized with SPECT. The kinetics of 123I-ß-CIT was similar to that in previously published autoradiography studies. Binding potential mean values of the test-retest studies were 6.6 ± 15.7% and 6.6 ± 4.6%, respectively, and the variability was 9%. The SPECT template was aggregated from the first and second imaging of the test-retest animals. No significant difference between the templates (P > 0.05) was found. From the test template, a striatal volume of 22.3 mm3 was defined. CONCLUSIONS: This study demonstrates that high-resolution SPECT/CT is capable of accurate, repeatable, and semiquantitative measurement of 123I-ß-CIT DAT binding in the mouse brain. This methodology will enable further studies on DAT density and neuroprotective properties of drugs in mice.

Pre-targeting and direct immunotargeting of liposomal drug carriers to ovarian carcinoma.

BACKGROUND: Epidermal growth factor receptor (EGFR) is overexpressed in many solid tumor types, such as ovarian carcinoma. Immunoliposome based drug targeting has shown promising results in drug delivery to the tumors. However, the ratio of tumor-to-normal tissue concentrations should be increased to minimize the adverse effects of cytostatic drugs. METHODOLOGY/PRINCIPAL FINDINGS: We studied the EGFR-targeted doxorubicin immunoliposomes using pre-targeting and local intraperitoneal (i.p.) administration of the liposomes. This approach was used to increase drug delivery to tumors as compared to direct intravenous (i.v.) administration of liposomes. EGFR antibodies were attached on the surface of PEG coated liposomes using biotin-neutravidin binding. Receptor mediated cellular uptake and cytotoxic efficacy of EGFR-targeted liposomes were investigated in human ovarian adenocarcinoma (SKOV-3 and SKOV3.ip1) cells. In vivo distribution of the liposomes in mice was explored using direct and pre-targeting approaches and SPECT/CT imaging. Targeted liposomes showed efficient and specific receptor-mediated binding to ovarian carcinoma cells in vitro, but the difference in cytotoxicity between targeted and non-targeted liposomes remained small. The relatively low cytotoxic efficacy is probably due to insufficient doxorubicin release from the liposomes rather than lack of target binding. Tumor uptake of targeted liposomes in vivo was comparable to that of non-targeted liposomes after both direct and pre-targeting administration. For both EGFR-targeted and non-targeted liposomes, the i.p. administration increased liposome accumulation to the tumors compared to i.v. injections. CONCLUSIONS/SIGNIFICANCE: Intraperitoneal administration of liposomes may be a beneficial approach to treat the tumors in the abdominal cavity. The i.p. pre-targeting method warrants further studies as a potential approach in cancer therapy.

Oncolytic adenovirus ICOVIR-7 in patients with advanced and refractory solid tumors.

PURPOSE: Twenty-one patients with cancer were treated with a single round of oncolytic adenovirus ICOVIR-7. EXPERIMENTAL DESIGN: ICOVIR-7 features an RGD-4C modification of the fiber HI-loop of serotype 5 adenovirus for enhanced entry into tumor cells. Tumor selectivity is mediated by an insulator, a modified E2F promoter, and a Rb-binding site deletion of E1A, whereas replication is optimized with E2F binding hairpins and a Kozak sequence. ICOVIR-7 doses ranged from 2 x 10(10) to 1 x 10(12) viral particles. All patients had advanced and metastatic solid tumors refractory to standard therapies. RESULTS: ICOVIR-7 treatment was well tolerated with mild to moderate fever, fatigue, elevated liver transaminases, chills, and hyponatremia. One patient had grade 3 anemia but no other serious side effects were seen. At baseline, 9 of 21 of patients had neutralizing antibody titers against the ICOVIR-7 capsid. Treatment resulted in neutralizing antibody titer induction within 4 weeks in 16 of 18 patients. No elevations of serum proinflammatory cytokine levels were detected. Viral genomes were detected in the circulation in 18 of 21 of patients after injection and 7 of 15 of the samples were positive 2 to 4 weeks later suggesting viral replication. CONCLUSIONS: Overall, objective evidence of antitumor activity was seen in 9 of 17 evaluable patients. In radiological analyses, 5 of 12 evaluable patients had stabilization or reduction in tumor size. These consisted of one partial response, two minor responses and two cases of stable disease, all occurring in patients who had progressive disease before treatment. In summary, ICOVIR-7 treatment is apparently safe, resulting in anticancer activity, and is therefore promising for further clinical testing.

Oncolytic adenovirus coding for granulocyte macrophage colony-stimulating factor induces antitumoral immunity in cancer patients.

Granulocyte macrophage colony-stimulating factor (GMCSF) can mediate antitumor effects by recruiting natural killer cells and by induction of tumor-specific cytotoxic T-cells through antigen-presenting cells. Oncolytic tumor cell-killing can produce a potent costimulatory danger signal and release of tumor epitopes for antigen-presenting cell sampling. Therefore, an oncolytic adenovirus coding for GMCSF was engineered and shown to induce tumor-specific immunity in an immunocompetent syngeneic hamster model. Subsequently, 20 patients with advanced solid tumors refractory to standard therapies were treated with Ad5-D24-GMCSF. Of the 16 radiologically evaluable patients, 2 had complete responses, 1 had a minor response, and 5 had disease stabilization. Responses were frequently seen in injected and noninjected tumors. Treatment was well tolerated and resulted in the induction of both tumor-specific and virus-specific immunity as measured by ELISPOT and pentamer analysis. This is the first time that oncolytic virus-mediated antitumor immunity has been shown in humans. Ad5-D24-GMCSF is promising for further clinical testing.