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VCU Theses and Dissertations

Indocyanine green (IC-Green), the only FDA approved near-infrared (NIR) fluorophore for clinical use, is attractive to researchers for the development of targeted optical imaging agents by modification of its structure and conjugation to monoclonal antibodies (mAbs) or their fragments. IC-Green derivative, ICG-sulfo-OSu (ICG-sOSu), is frequently used for antibody conjugation. However, ICG-sOSu is amphiphilic and readily facilitates aggregation of mAbs that is not easily separable from the desired immunoconjugates. Complications originating from this behavior are frequently overlooked by researchers. This study examined detailed chemical and biological characteristics of an ICG-sOSu-labeled mAb, panitumumab, and provided a clinically applicable strategy to deliver a pure conjugation product. Size-exclusion high-performance liquid chromatography (SE-HPLC) analysis of conjugation reactions, performed at molar reaction ratios of ICG-sOSu: mAb of 5, 10, or 20, resulted in isolable desired ICG-sOSu-panitumumab conjugation product in 72%, 53%, and 19% yields, respectively, with the remainder consisting of high molecular weight aggregates (>150 kDa) 14%, 30%, and 51%, respectively. The HPLC-purified ICG-sOSu-panitumumab products were analyzed by native and SDS polyacrylamide gel electrophoresis (PAGE) followed by optical imaging. Results indicated that the interaction between ICG-sOSu and panitumumab was due to both covalent and noncovalent binding of the ICG-sOSu to the protein. Noncovalently bound dye in the ICG-sOSu-panitumumab conjugate products was removed by extraction with ethyl acetate to further purify the HPLC-isolated conjugation products. With conserved immunoreactivity, excellent target-specific uptake of the doubly purified bioconjugates was observed with minimal liver retention in athymic nude mice bearing HER1-expressing tumor xenografts. In summary, the preparation of well-defined bioconjugate products labeled with commercial ICG-sOSu dye is not a simple process and control of the conjugation reaction ratio and conditions is crucial. Furthermore, absolute purification and characterization of the products is necessitated prior to in vivo optical imaging. Use of validated and characterized dye conjugate products should facilitate the development of clinically viable and reproducible IC-Green derivative and other NIR dye mAb conjugates for optical imaging applications.

The hedgehog (Hh) pathway is aberrantly activated in a number of tumors. In medulloblastoma, basal cell carcinoma, and rhabdomyosarcoma, mutations in Hh pathway genes lead to ligand-independent pathway activation. In many other tumor types, ligand-dependent activation of Hh signaling is potentiated through crosstalk with other critical molecular signaling pathways. Among such pathways, RAS/RAF/MEK/ERK, PI3K/AKT/mTOR, EGFR, and Notch are of particular interest because agents that selectively inhibit these pathways are available and can be readily combined with agents such as vismodegib, sonidegib (LDE225), and BMS-833923, which target smoothened-a key Hh pathway regulator. Numerous preclinical studies have revealed the ways in which Hh intersects with each of these pathways, and combination therapies have resulted in improved antitumor efficacy and survival in animal models. Hh also plays an important role in hematopoiesis and in the maintenance of BCR-ABL-driven leukemic stem cells. Thus, combined inhibition of the Hh pathway and BCR-ABL has emerged as a promising potential therapeutic strategy in chronic myeloid leukemia (CML). A number of clinical trials evaluating combinations of Hh inhibitors with other targeted agents are now underway in CML and a variety of solid tumors. This review highlights these trials and summarizes preclinical evidence of crosstalk between Hh and four other actionable pathways-RAS/RAF/MEK/ERK, PI3K/AKT/mTOR, EGFR, and Notch-as well as the role of Hh in the maintenance of BCR-ABL-driven leukemic stem cells.

Intracellular mRNA localization is a conserved mechanism for spatially regulating protein production in polarized cells, such as neurons. The mRNA encoding the translational repressor Nanos (Nos) forms ribonucleoprotein (RNP) particles that are dendritically localized inDrosophilalarval class IV dendritic arborization (da) neurons. Innosmutants, class IV da neurons exhibit reduced dendritic branching complexity, which is rescued by transgenic expression of wild-typenosmRNA but not by a localization-compromisednosderivative. While localization is essential fornosfunction in dendrite morphogenesis, the mechanism underlying the transport ofnosRNP particles was unknown. We investigated the mechanism of dendriticnosmRNA localization by analyzing requirements fornosRNP particle motility in class IV da neuron dendrites through live imaging of fluorescently labelednosmRNA. We show that dynein motor machinery components mediate transport ofnosmRNA in proximal dendrites. Two factors, the RNA-binding protein Rumpelstiltskin and the germ plasm protein Oskar, which are required for diffusion/entrapment-mediated localization ofnosduring oogenesis, also function in da neurons for formation and transport ofnosRNP particles. Additionally, we show thatnosregulates neuronal function, most likely independent of its dendritic localization and function in morphogenesis. Our results reveal adaptability of localization factors for regulation of a target transcript in different cellular contexts.

Introduction Alpha particles possess an exquisite degree of cytotoxicity when employed for targeted α-particle therapy (TAT) or radioimmunotherapy (RIT). 212 Pb, which acts as an in vivo generator of the α-emitting nuclide 212 Bi has shown great promise in pre-clinical studies when used to label the HER2 binding antibody, trastuzumab. Currently, the first RIT clinical trial employing 212 Pb radiolabeled trastuzumab is in progress. This report provides detailed current protocol operations and steps that were generated for use in the clinical trial as well as the relevant pre-clinical experimentation, and describes in detail the labeling of proteins or peptides with 212 Pb as provided via a 224 Ra based generator system. Methods 212 Pb was eluted from the 224 Ra/ 212 Pb generator using hydrochloric acid (2M). The generator eluate was evaporated and digested with nitric acid (8M) followed by extraction of the 212 Pb with dilute nitric acid (0.1M). The dilute nitric acid solution of 212 Pb was used to label the immunoconjugate Trastuzumab-TCMC (2-(4-isothiocyanatobenzyl-1,4,7,10-tetraaza-1,4,7,10,tetra-(2-carbamonylmethyl)-cyclododecane) at pH5.5. Results Elution of 212 Pb from the generator was efficient yielding>90% of available 212 Pb. Trastuzumab-TCMC was efficiently labeled with a radiochemical yield of 94%±4% (n=7) by ITLC and an isolated yield of 73%±3% (n=7). Conclusions The results show the feasibility of generating radioimmunoconjugates and peptide conjugates for use as in vivo α generator systems in the clinic. The technology holds promise in applications involving the treatment of minimal disease such as micrometastases and residual tumor after surgical debulking, hematological cancers, infections, and compartmental cancers, such as ovarian cancer.

Despite the great potential of targeted α-radioimmunotherapy (RIT) as demonstrated by pre-clinical and clinical trials, limited progress has been made on the improvement of chelation chemistry for (212)Bi and (213)Bi. A new bifunctional ligand 3p-C-NETA was evaluated for targeted α RIT using (212)Bi and (213)Bi.Radiolabeling of 3p-C-NETA with (205/6)Bi, a surrogate of (212)Bi and (213)Bi, was evaluated at pH5.5 and room temperature. In vitro stability of the (205/6)Bi-3p-C-NETA-trastuzumab conjugate was evaluated using human serum (pH7, 37 °C). Immunoreactivity and specific activity of the (205/6)Bi-3p-C-NETA-trastuzumab conjugate were measured. An in vivo biodistribution study was performed to evaluate the in vivo stability and tumor targeting properties of the (205/6)Bi-3p-C-NETA-trastuzumab conjugate in athymic mice bearing subcutaneous LS174T tumor xenografts.The 3p-C-NETA-trastuzumab conjugate was extremely rapid in complexing with (205/6)Bi, and the corresponding (205/6)Bi-3p-C-NETA-trastuzumab was stable in human serum. (205/6)Bi-3p-C-NETA-trastuzumab was prepared with a high specific activity and retained immunoreactivity. (205/6)Bi-3p-C-NETA-trastuzumab conjugate displayed excellent in vivo stability and targeting as evidenced by low normal organ and high tumor uptake.The results of the in vitro and in vivo studies indicate that 3p-C-NETA is a promising chelator for RIT applications using (212)Bi and (213)Bi. Further detailed in vivo evaluations of 3p-C-NETA for targeted α RIT are warranted.

The studies described herein assess the potential of combining platinum-based chemotherapy with high-linear energy transfer (LET) α-particle-targeted radiation therapy using trastuzumab as the delivery vehicle. An initial study explored the combination of cisplatin with (213)Bi-trastuzumab in the LS-174T i.p. xenograft model. This initial study determined the administration sequence of cisplatin and (213)Bi-trastuzumab. Cisplatin coinjected with (213)Bi-trastuzumab increased the median survival (MS) to 90 days versus 65 days for (213)Bi-trastuzumab alone. Toxicity was observed with a weight loss of 17.6% in some of the combined treatment groups. Carboplatin proved to be better tolerated. Maximal therapeutic benefit, that is, a 5.1-fold increase in MS, was obtained in the group injected with (213)Bi-trastuzumab, followed by carboplatin 24 hours later. This was further improved by administration of multiple weekly doses of carboplatin. The MS achieved with administration of 3 doses of carboplatin was 180 days versus 60 days with (213)Bi-trastuzumab alone. The combination of carboplatin with (212)Pb radioimmunotherapy was also evaluated. The therapeutic efficacy of (212)Pb-trastuzumab (58-day MS) increased when the mice were pretreated with carboplatin 24 hours prior (157-day MS). These results again demonstrate the necessity of empirically determining the administration sequence when combining therapeutic modalities.

Background: Paclitaxel has recently been reported by this laboratory to potentiate the high-LET radiation therapeutic 212Pb-TCMC-trastuzumab, which targets HER2. To elucidate mechanisms associated with this therapy, targeted α-particle radiation therapeutic 212Pb-TCMC-trastuzumab together with paclitaxel was investigated for the treatment of disseminated peritoneal cancers. Methods: Mice bearing human colon cancer LS-174T intraperitoneal xenografts were pre-treated with paclitaxel, followed by treatment with 212Pb-TCMC-trastuzumab and compared with groups treated with paclitaxel alone, 212Pb-TCMC-HuIgG, 212Pb-TCMC-trastuzumab and 212Pb-TCMC-HuIgG after paclitaxel pre-treatment. Results: 212Pb-TCMC-trastuzumab with paclitaxel given 24 h earlier induced increased mitotic catastrophe and apoptosis. The combined modality of paclitaxel and 212Pb-TCMC-trastuzumab markedly reduced DNA content in the S-phase of the cell cycle with a concomitant increase observed in the G2/M-phase. This treatment regimen also diminished phosphorylation of histone H3, accompanied by an increase in multi-micronuclei, or mitotic catastrophe in nuclear profiles and positively stained γH2AX foci. The data suggests, possible effects on the mitotic spindle checkpoint by the paclitaxel and 212Pb-TCMC-trastuzumab treatment. Consistent with this hypothesis, 212Pb-TCMC-trastuzumab treatment in response to paclitaxel reduced expression and phosphorylation of BubR1, which is likely attributable to disruption of a functional Aurora B, leading to impairment of the mitotic spindle checkpoint. In addition, the reduction of BubR1 expression may be mediated by the association of a repressive transcription factor, E2F4, on the promoter region of BubR1 gene. Conclusion: These findings suggest that the sensitisation to therapy of 212Pb-TCMC-trastuzumab by paclitaxel may be associated with perturbation of the mitotic spindle checkpoint, leading to increased mitotic catastrophe and cell death.

Purpose To elucidate the mechanism of the therapeutic efficacy of targeted α-particle radiation therapy using 212 Pb-TCMC-trastuzumab together with gemcitabine for treatment of disseminated peritoneal cancers. Methods and Materials Mice bearing human colon cancer LS-174T intraperitoneal xenografts were pretreated with gemcitabine, followed by 212 Pb-TCMC-trastuzumab and compared with controls. Results Treatment with 212 Pb-TCMC-trastuzumab increased the apoptotic rate in the S-phase-arrested tumors induced by gemcitabine at earlier time points (6 to 24 hours). 212 Pb-TCMC-trastuzumab after gemcitabine pretreatment abrogated G2/M arrest at the same time points, which may be associated with the inhibition of Chk1 phosphorylation and, in turn, cell cycle perturbation, resulting in apoptosis. 212 Pb-TCMC-trastuzumab treatment after gemcitabine pretreatment caused depression of DNA synthesis, DNA double-strand breaks, accumulation of unrepaired DNA, and down-regulation of Rad51 protein, indicating that DNA damage repair was blocked. In addition, modification in the chromatin structure of p21 may be associated with transcriptionally repressed chromatin states, indicating that the open structure was delayed at earlier time points. Conclusion These findings suggest that the cell-killing efficacy of 212 Pb-TCMC-trastuzumab after gemcitabine pretreatment may be associated with abrogation of the G2/M checkpoint, inhibition of DNA damage repair, and chromatin remodeling.

With the advent of molecularly targeted agents, treatment of metastatic renal cell carcinoma (mRCC) has improved significantly. Agents targeting the vascular endothelial growth factor receptor (VEGFR) and the mammalian target of rapamycin complex 1 (mTORC1) are more effective and less toxic than previous standards of care involving cytotoxic and cytokine therapies. Unfortunately, many patients relapse following treatment with VEGFR and mTORC1 inhibitors as a result of acquired resistance mechanisms, which are thought to lead to the reestablishment of tumor vasculature. Specifically, the loss of negative feedback loops caused by inhibition of mTORC1 leads to upregulation of downstream effectors of the phosphoinositide 3-kinase (PI3K)/AKT/mTOR pathway and subsequent activation of hypoxia-inducible factor, an activator of angiogenesis. De novo resistance involving activated PI3K signaling has also been observed. These observations have led to the development of novel agents targeting PI3K, mTORC1/2 and PI3K/mTORC1/2, which have demonstrated antitumor activity in preclinical models of RCC. Several agents--BKM120, BEZ235 and GDC-0980--are being investigated in clinical trials in patients with metastatic/advanced RCC, and similar agents are being tested in patients with solid tumors. The future success of mRCC treatment will likely involve a combination of agents targeting the multiple pathways involved in angiogenesis, including VEGFR, PI3K and mTORC1/2.

An α-particle, a 4He nucleus, is exquisitely cytotoxic and indifferent to many limitations associated with conventional chemo- and radiotherapy. The exquisite cytotoxicity of α-radiation, the result of its high mean energy deposition [high linear energy transfer (LET)] and limited range in tissue, provides for a highly controlled therapeutic modality that can be targeted to selected malignant cells [targeted α-therapy (TAT)] with minimal normal tissue effects. A burgeoning interest in the development of TAT is buoyed by the increasing number of ongoing clinical trials worldwide. The short path length renders α-emitters suitable for treatment and management of minimal disease such as micrometastases or residual tumor after surgical debulking, hematologic cancers, infections, and compartmental cancers such as ovarian cancer or neoplastic meningitis. Yet, despite decades of study of high LET radiation, the mechanistic pathways of the effects of this modality remain not well defined. The modality is effectively presumed to follow a simple therapeutic mechanism centered on catastrophic double-strand DNA breaks without full examination of the actual molecular pathways and targets that are activated that directly affect cell survival or death. This Molecular Pathways article provides an overview of the mechanisms and pathways that are involved in the response to and repair of TAT-induced DNA damage as currently understood. Finally, this article highlights the current state of clinical translation of TAT as well as other high-LET radionuclide radiation therapy using α-emitters such as 225Ac, 211At, 213Bi, 212Pb, and 223Ra. Clin Cancer Res; 19(3); 530–7. ©2012 AACR.

We have created a potential targeted drug delivery platform with three imaging reporters by coupling the magnetic properties of USPIOs with near infrared fluorescence of Cy5.5 and γ-emissions of 111In that is chelated to a conjugated antibody. The nanoparticle will allow for not only triple verification of localization, but also quantification. During each phase of development, the nanoparticles have been characterized for surface charge and structure by transmission electron microscopy and dynamic light scattering. Magnetic properties including hysteresis measurements and field cooling analyses were conducted using a superconducting quantum interference device. In vitro analyses of flow cytometry and cell viability as well as in vivo imaging studies have been conducted.

IgG has a long half-life through engagement of its Fc region with the neonatal Fc receptor (FcRn). The FcRn binding site on IgG1 has been shown to contain I253 and H310 in the CH2 domain and H435 in the CH3 domain. Altering the half-life of IgG has been pursued with the aim to prolong or reduce the half-life of therapeutic IgGs. More recent studies have shown that IgGs bind differently to mouse and human FcRn. In this study we characterize a set of hu3S193 IgG1 variants with mutations in the FcRn binding site. A double mutation in the binding site is necessary to abrogate binding to murine FcRn, whereas a single mutation in the FcRn binding site is sufficient to no longer detect binding to human FcRn and create hu3S193 IgG1 variants with a half-life similar to previously studied hu3S193 F(ab')2 (t1/2β, I253A, 12.23 h; H310A, 12.94; H435A, 12.57; F(ab')2, 12.6 h). Alanine substitutions in S254 in the CH2 domain and Y436 in the CH3 domain showed reduced binding in vitro to human FcRn and reduced elimination half-lives in huFcRn transgenic mice (t1/2β, S254A, 37.43 h; Y436A, 39.53 h; wild-type, 83.15 h). These variants had minimal effect on half-life in BALB/c nu/nu mice (t1/2β, S254A, 119.9 h; Y436A, 162.1 h; wild-type, 163.1 h). These results provide insight into the interaction of human Fc by human FcRn, and are important for antibody-based therapeutics with optimal pharmacokinetics for payload strategies used in the clinic.

Radiolabeled antibodies (mAbs) provide efficient tools for cancer therapy. The combination of low energy β(-)-emissions (500 keVmax; 130 keVave) along with a γ-emission for imaging makes (177)Lu (T1/2 = 6.7 day) a suitable radionuclide for radioimmunotherapy (RIT) of tumor burdens possibly too large to treat with α-particle radiation. RIT with (177)Lu-trastuzumab has proven to be effective for treatment of disseminated HER2 positive peritoneal disease in a pre-clinical model. To elucidate mechanisms originating from this RIT therapy at the molecular level, tumor bearing mice (LS-174T intraperitoneal xenografts) were treated with (177)Lu-trastuzumab comparatively to animals treated with a non-specific control, (177)Lu-HuIgG, and then to prior published results obtained using (212)Pb-trastuzumab, an α-particle RIT agent. (177)Lu-trastuzumab induced cell death via DNA double strand breaks (DSB), caspase-3 apoptosis, and interfered with DNA-PK expression, which is associated with the repair of DNA non-homologous end joining damage. This contrasts to prior results, wherein (212)Pb-trastuzumab was found to down-regulate RAD51, which is involved with homologous recombination DNA damage repair. (177)Lu-trastuzumab therapy was associated with significant chromosomal disruption and up-regulation of genes in the apoptotic process. These results suggest an inhibition of the repair mechanism specific to the type of radiation damage being inflicted by either high or low linear energy transfer radiation. Understanding the mechanisms of action of β(-)- and α-particle RIT comparatively through an in vivo tumor environment offers real information suitable to enhance combination therapy regimens involving α- and β(-)-particle RIT for the management of intraperitoneal disease.

Alpha-particle emitters have a high linear energy transfer and short range, offering the potential for treating micrometastases while sparing normal tissues. We developed a urea-based, 211At-labeled small molecule targeting prostate-specific membrane antigen (PSMA) for the treatment of micrometastases due to prostate cancer (PC). Methods: PSMA-targeted (2S)-2-(3-(1-carboxy-5-(4-211At-astatobenzamido)pentyl)ureido)-pentanedioic acid (211At-6) was synthesized. Cellular uptake and clonogenic survival were tested in PSMA-positive (PSMA+) PC3 PIP and PSMA-negative (PSMA−) PC3 flu human PC cells after 211At-6 treatment. The antitumor efficacy of 211At-6 was evaluated in mice bearing PSMA+ PC3 PIP and PSMA– PC3 flu flank xenografts at a 740-kBq dose and in mice bearing PSMA+, luciferase-expressing PC3-ML micrometastases. Biodistribution was determined in mice bearing PSMA+ PC3 PIP and PSMA– PC3 flu flank xenografts. Suborgan distribution was evaluated using α-camera images, and microscale dosimetry was modeled. Long-term toxicity was assessed in mice for 12 mo. Results: 211At-6 treatment resulted in PSMA-specific cellular uptake and decreased clonogenic survival in PSMA+ PC3 PIP cells and caused significant tumor growth delay in PSMA+ PC3 PIP flank tumors. Significantly improved survival was achieved in the newly developed PSMA+ micrometastatic PC model. Biodistribution showed uptake of 211At-6 in PSMA+ PC3 PIP tumors and in kidneys. Microscale kidney dosimetry based on α-camera images and a nephron model revealed hot spots in the proximal renal tubules. Long-term toxicity studies confirmed that the dose-limiting toxicity was late radiation nephropathy. Conclusion: PSMA-targeted 211At-6 α-particle radiotherapy yielded significantly improved survival in mice bearing PC micrometastases after systemic administration. 211At-6 also showed uptake in renal proximal tubules resulting in late nephrotoxicity, highlighting the importance of long-term toxicity studies and microscale dosimetry.

OP03 Selective extraction of medically-related radionuclides from proton-irradiated thorium targets, V. Radchenko, J.W. Engle, C. Roy, J. Griswold, M.F. Nortier, E.R. Birnbaum, M. Brugh, S. Mirzadeh, K. D. John, M.E. Fassbender, OP04 Comparison of [68Ga]FSC(succ-RGD)3 and [68Ga]NODAGA-RGD for PET imaging of αvβ3 integrin expression, Chuangyan Zhai, Gerben M. Franssen, Milos Petrik, Peter Laverman, Clemens Decristoforo, OP05 A new NPY-Y1R targeting peptide for breast cancer PET imaging, Ait-Mohand Samia, Dumulon-Perreault Véronique, Guérin Brigitte, OP06 The influence of multivalency on CCK 2 receptor targeting, D. Summer, A. Kroess, C. Rangger, H. Haas, P. Laverman, F. Gerben, E. von Guggenberg, C.Decristoforo, OP07 SPECT Imaging of αvβ3 Expression by [99mTc(N)PNP43]- Bifunctional Chimeric RGD Peptide not Cross-Reacting with αvβ5, Cristina Bolzati, Nicola Salvarese, Fiorenzo Refosco, Laura Meléndez-Alafort, Debora Carpanese, Antonio Rosato, Michele Saviano, Annarita Del Gatto, Daniela Comegna, Laura Zaccaro, OP09 New dienophiles for the inverse-electron-demand Diels-Alder reaction and for pretargeted PET imaging, Emilie Billaud, Muneer Ahamed, Frederik Cleeren, Elnaz Shahbazali, Tim Noël, Volker Hessel, Alfons Verbruggen and Guy Bormans, OP10 New complexing agent for Al18F-labelling of heat-sensitive biomolecules: Synthesis and preclinical evaluation of Al18F-RESCA1-HAS, Cleeren F, Lecina J, Koole M, Verbruggen A and Bormans G, OP11 A novel versatile precursor efficient for F-18 radiolabelling via click-chemistry, B. Lugatoa, S. Stucchia, E.A. Turollaa, L. Giulianoa, S.Toddea, P. Ferraboschib, OP12 A general applicable method to quantify unidentified UV impurities in radiopharmaceuticals, R.P. Klok, M.P.J. Mooijer, N.H. Hendrikse, A.D. Windhorst, OP13 Development of [18F]Fluoro-C-glycosides to radiolabel peptides, Collet C., Petry N., Chrétien F., Karcher G., Pellegrini-Moïse N., Lamandé-Langle S., OP14 A Microfluidic Approach for the 68Ga-labeling of PSMAHBED-CC and NODAGA-RGD, Sarah Pfaff, Cecile Philippe, Markus Mitterhauser, Marcus Hacker, Wolfgang Wadsak, OP16 Surprising reactivity of astatine in the nucleophilic substitution of aryliodonium salts: application to the radiolabeling of antibodies, François Guérard, Yong-Sok Lee, Sébastien Gouard, Kwamena Baidoo, Cyrille Alliot, Michel Chérel, Martin W. Brechbiel, Jean-François Gestin, OP17 64Cu-NOTA-pertuzumab F(ab')2 fragments, a second-generation probe for PET imaging of the response of HER2-positive breast cancer to trastuzumab (Herceptin), Lam K, Chan C, Reilly RM, OP18 Development of radiohalogenated analogues of a avb6-specific peptide for high LET particle emitter targeted radionuclide therapy of cancer, Salomé Paillas, John Marshall, Jean-Pierre Pouget, Jane Sosabowski, OP19 Ligand Specific Efficiency (LSE) as a guide in tracer optimization, Emmanuelle Briard, Yves P. Auberson, John Reilly, Mark Healy, David Sykes, OP23 The radiosynthesis of an 18F-labeled triglyceride, developed to visualize and quantify brown adipose tissue activity, Andreas Paulus, Wouter van Marken Lichtenbelt,Felix Mottaghy, Matthias Bauwens, OP24 Influence of the fluorescent dye on the tumor targeting properties of dual-labeled HBED-CC based PSMA inhibitors, Baranski, Ann-Christin, Schäfer, Martin, Bauder-Wüst, Ulrike, Haberkorn, Uwe, Eder, Matthias, Kopka, Klaus, OP25 [18F]MEL050 as a melanin PET tracer : fully automated radiosynthesis and evaluation for the detection of pigmented melanoma in mice pulmonary metastases, Chaussard M, Hosten B, Vignal N, Tsoupko-Sitnikov V, Hernio N, Hontonnou F, Merlet P, Poyet JL, Sarda-Mantel L, Rizzo-Padoin N, OP26 Design and Preclinical Evaluation of Novel Radiofluorinated PSMA Targeting Ligands Based on PSMA-617, J. Cardinale, M. Schäfer, M. Benešová, U. Bauder-Wüst, O. Seibert, F. Giesel, U. Haberkorn, M. Eder, K. Kopka, OP27 A novel radiolabeled peptide for PET imaging of prostate cancer: 64Cu-DOTHA2-PEG-RM26, Mansour Nematallah, Paquette Michel, Ait-Mohand Samia, Dumulon-Perreault Véronique, Lecomte Roger, Guérin Brigitte, OP29 Biodistribution of [18F]Amylovis®, a new radiotracer PET imaging of β-amyloid plaques, Fernandez-Maza L, Rivera-Marrero S, Prats Capote A, Parrado-Gallego A, Fernandez-Gomez I, Balcerzyk M, Sablon-Carrazana M, Perera-Pintado A, Merceron-Martinez D, Acosta-Medina E, Rodriguez-Tanty C, OP30 Synthesis and preclinical evaluation of [11C]-BA1 PET tracer for the imaging of CSF-1R, Bala Attili, Muneer Ahamed, Guy Bormans, OP31 In vivo imaging of the MCHR1 in the ventricular system via [18F]FE@SNAP, C. Philippe, M. Zeilinger, T. Scherer, C. Fürnsinn, M. Dumanic, W. Wadsak, M. Hacker, M. Mitterhauser, OP32 Synthesis of the first carbon-11 labelled P2Y12 receptor antagonist for imaging the anti-inflammatory phenotype of activated microglia, B. Janssen, D.J. Vugts, G.T. Molenaar, U. Funke, P.S. Kruijer, F. Dollé, G. Bormans, A.A. Lammertsma, A.D. Windhorst, OP33 Radiosynthesis of a selective HDAC6 inhibitor [11C]KB631 and in vitro and ex vivo evaluation, Koen Vermeulen, Muneer Ahamed, Michael Schnekenburger, Mathy Froeyen, Dag Erlend Olberg, Marc Diederich, Guy Bormansa, OP34 Improving metabolic stability of fluorine-18 labelled verapamil analogues, Raaphorst RM, Luurtsema G, Lammertsma AA, Elsinga PH, Windhorst AD, OP36 Development of a novel PET tracer for the activin receptor-like kinase 5, Lonneke Rotteveel, Uta Funke, Peter ten Dijke, Harm Jan Bogaard, Adriaan A. Lammertsma, Albert D. Windhorst, OP37 SPECT imaging and biodistribution studies of 111In-EGF-Au-PEG nanoparticles in vivo, Lei Song, Sarah Able, Nadia Falzone, Veerle Kersemans, Katherine Vallis, OP38 Melanoma targeting with [99mTc(N)(PNP3)]-labeled NAPamide derivatives: preliminary pharmacological studies, Davide Carta, Nicola Salvarese, Wiebke Sihver, Feng Gao, Hans Jürgen Pietzsch, Barbara Biondi, Paolo Ruzza, Fiorenzo Refosco, Cristina Bolzati, OP39 [68Ga]NODAGA-RGD: cGMP synthesis and data from a phase I clinical study, Roland Haubner, Armin Finkensted, Armin Stegmair, Christine Rangger, Clemens Decristoforo, Heinz Zoller, Irene J. Virgolin, OP44 Implementation of a GMP-grade radiopharmacy facility in Maastricht, Ivo Pooters, Maartje Lotz, Roel Wierts, Felix Mottaghy, Matthias Bauwens, OP45 Setting up a GMP production of a new radiopharmaceutical, Forsback, Sarita, Bergman Jörgen, Kivelä Riikka, OP48 In vitro and in vivo evaluation of 68-gallium labeled Fe3O4-DPD nanoparticles as potential PET/MRI imaging agents, M. Karageorgou, M. Radović, C. Tsoukalas, B. Antic, M. Gazouli, M. Paravatou-Petsotas, S. Xanthopouls, M. Calamiotou, D. Stamopoulos, S. Vranješ-Durić, P. Bouziotis, OP49 Fast PET imaging of inflammation using 68Ga-citrate with Fe-containing salts of hydroxy acids, A. S. Lunev, A. A. Larenkov, K.A. Petrosova, O. E. Klementyeva, G. E. Kodina, PP01 Installation and validation of 11C-methionine synthesis, Kvernenes, O.H., Adamsen, T.C.H., PP02 Fully automated synthesis of 68Ga-labelled peptides using the IBA Synthera® and Synthera® Extension modules, René Martin, Sebastian Weidlich, Anna-Maria Zerges, Cristiana Gameiro, Neva Lazarova, Marco Müllera, PP03 GMP compliant production of 15O-labeled water using IBA 18 MeV proton cyclotron, Gert Luurtsema, Michèl de Vries, Michel Ghyoot, Gina van der Woude, Rolf Zijlma, Rudi Dierckx, Hendrikus H. Boersma, Philip H. Elsinga, PP04 In vitro Nuclear Imaging Potential of New Subphthalocyanine and Zinc Phthalocyanine, Fatma Yurt Lambrecht, Ozge Er, Mine Ince, Cıgır Biray Avci, Cumhur Gunduz, Fatma Aslihan Sarı, PP05 Synthesis, Photodynamic Therapy Efficacy and Nuclear Imaging Potential of Zinc Phthalocyanines, Kasim Ocakoglu, Ozge Er, Onur Alp Ersoz, Fatma Yurt Lambrecht, Mine Ince, Cagla Kayabasi, Cumhur Gunduz, PP06 Radio-U(H)PLC – the Search on the Optimal Flow Cell for the γ-Detector, Torsten Kniess, Sebastian Meister, Steffen Fischer, Jörg Steinbach, PP07 Radiolabeling, characterization & biodistribution study of cysteine and its derivatives with Tc99m, Rabia Ashfaq, Saeed Iqbal, Atiq-ur-Rehman, Irfan ullah Khan, PP08 Radiolabelling of poly (lactic-co.glycolic acid) (PLGA) nanoparticles with 99mTC, R Iglesias-Jerez, Cayero-Otero, L. Martín-Banderas, A. Perera-Pintado, I. Borrego-Dorado, PP09 Development of [18F]PD-410 as a non-peptidic PET radiotracer for gastrin releasing peptide receptors, Ines Farinha-Antunes, Chantal Kwizera, Enza Lacivita, Ermelinda Lucente, Mauro Niso, Paola De Giorgio, Roberto Perrone, Nicola A. Colabufo, Philip H. Elsinga, Marcello Leopoldo, PP10 An improved nucleophilic synthesis of 2-(3,4-dimethoxyphenyl)-6-(2-[18F]fluoroethoxy) benzothiazole ([18F]FEDMBT), potential diagnostic agent for breast cancer imaging by PET, V.V. Vaulina, O.S. Fedorova, V.V. Orlovskaja, ?�.L. Chen, G.Y. Li, F.C. Meng, R.S. Liu, H.E. Wang, R.N. Krasikova, PP11 Internal radiation dose assessment of radiopharmaceuticals prepared with accelerator-produced 99mTc, Laura Meléndez-Alafort, Mohamed Abozeid, Guillermina Ferro-Flores, Anna Negri, Michele Bello, Nikolay Uzunov, Martha Paiusco, Juan Esposito, Antonio Rosato, PP12 A specialized five-compartmental model software for pharmacokinetic parameters calculation, Laura Meléndez-Alafort, Cristina Bolzati, Guillermina Ferro-Flores, Nicola Salvarese, Debora Carpanese, Mohamed Abozeid, Antonio Rosato, Nikolay Uzunov, PP13 Molecular imaging of the pharmacokinetic behavior of low molecular weight 18F-labeled PEtOx in comparison to 89Zr-labeled PEtOx, Palmieri L, Verbrugghen T, Glassner M, Hoogenboom R, Staelens S, Wyffels L, PP14 Towards nucleophilic synthesis of the α-[18F]fluoropropyl-L-dihydroxyphenylalanine, V. V. Orlovskaja, O. F. Kuznetsova, O. S. Fedorova, V. I. Maleev, Yu. N. Belokon, A. Geolchanyan, A. S. Saghyan, L. Mu, R. Schibli, S. M. Ametamey, R. N. Krasikova, PP15 A convenient one-pot synthesis of [18F]clofarabine, Revunov, Evgeny, Malmquist, Jonas, Johnström, Peter, Van Valkenburgh, Juno, Steele, Dalton, Halldin, Christer, Schou, Magnus, PP16 BODIPY-estradiol conjugates as multi-modality tumor imaging agents, Samira Osati,Michel Paquette,Simon Beaudoin,Hasrat Ali,Brigitte Guerin, Jeffrey V. Leyton, Johan E. van Lier, PP17 Easy and high yielding synthesis of 68Ga-labelled HBED-PSMA and DOTA-PSMA by using a Modular-Lab Eazy automatic synthesizer, Di Iorio V, Iori M, Donati C, Lanzetta V, Capponi PC, Rubagotti S, Dreger T, Kunkel F, Asti M, PP18 Synthesis and evaluation of fusarinine C-based octadentate bifunctional chelators for zirconium-89 labelling, Chuangyan Zhai, Christine Rangger, Dominik Summer, Hubertus Haas, Clemens Decristoforo, PP19 Fully automated production of [18F]NaF using a re-configuring FDG synthesis module., Suphansa Kijprayoon, Ananya Ruangma, Suthatip Ngokpol, Samart Tuamputsha, PP20 Extension of the Carbon-11 Small Labeling Agents Toolbox and Conjugate Addition, Ulrike Filp, Anna Pees, Carlotta Taddei, Aleksandra Pekošak, Antony D. Gee, Alex J. Poot, Albert D. Windhorst, PP21 In vitro studies on BBB penetration of pramipexole encapsulated theranostic liposomes for the therapy of Parkinson’s disease, Mine Silindir Gunay, A. Yekta Ozer, Suna Erdogan, Ipek Baysal, Denis Guilloteau, Sylvie Chalon, PP22 Factors affecting tumor uptake of 99mTc-HYNIC-VEGF165, Filippo Galli, Marco Artico, Samanta Taurone, Enrica Bianchi, Bruce D. Weintraub, Mariusz Skudlinski, Alberto Signore, PP23 Rhenium-188: a suitable radioisotope for targeted radiotherapy, Nicolas Lepareur, Nicolas Noiret, François Hindré, Franck Lacœuille, Eric Benoist, Etienne Garin, PP24 Preparation of a broad palette of 68Ga radiopharmaceuticals for clinical applications, Trejo-Ballado F, Zamora-Romo E, Manrique-Arias JC, Gama-Romero HM, Contreras-Castañon G, Tecuapetla-Chantes RG, Avila-Rodriguez MA, PP25 68Ga-peptide preparation with the use of two 68Ge/68Ga-generators, H. Kvaternik, D. Hausberger, C. Zink, B. Rumpf, R. M. Aigner, PP26 Assay of HEPES in 68Ga-peptides by HPLC, H. Kvaternik, D. Hausberger, B. Rumpf, R. M. Aigner, PP27 Preparation, in vitro and in vivo evaluation of a 99mTc(I)-Diethyl Ester (S,S)-Ethylenediamine- N,N´-DI-2-(3-Cyclohexyl) Propionic acid as a target-specific radiopharmaceutical, Drina Janković, Mladen Lakić, Aleksandar Savić, Slavica Ristić, Nadežda Nikolić, Aleksandar Vukadinović, Tibor J. Sabo, Sanja Vranješ-Đurić, PP28 90Y-labeled magnetite nanoparticles for possible application in cancer therapy, S. Vranješ-Đurić, M. Radović, D. Janković, N. Nikolić, G. F. Goya, P. Calatayud, V. Spasojević, B. Antić, PP29 Simplified automation of the GMP production of 68Ga-labelled peptides, David Goblet, Cristiana Gameiro, Neva Lazarova, PP30 Combining commercial production of multi-products in a GMP environment with Clinical & R&D activities, Cristiana Gameiro, Ian Oxley, Antero Abrunhosa, Vasko Kramer, Maria Vosjan, Arnold Spaans, PP31 99mTc(CO)3-labeling and Comparative In-Vivo Evaluation of Two Clicked cRGDfK Peptide Derivatives, Kusum Vats, Drishty Satpati, Haladhar D Sarma, Sharmila Banerjee, PP32 Application of AnaLig resin for 99mTc separation from molybdenum excess, Wojdowska W., Pawlak D.W., Parus L. J., Garnuszek P., Mikołajczak R., PP33 Constraints for selection of suitable precursor for one-step automated synthesis of [18F]FECNT, the dopamine transporter ligand, Pijarowska-Kruszyna J, Jaron A, Kachniarz A, Malkowski B, Garnuszek P, Mikolajczak R, PP34 Gamma scintigraphy studies with 99mTc- amoxicillin sodium in bacterially infected and sterile inflamed rats, Derya Ilem-Ozdemir, Oya Caglayan-Orumlu, Makbule Asikoglu, PP35 Preparation of 99mTc- Amoxicillin Sodium Lyophilized Kit, Derya Ilem-Ozdemir, Oya Caglayan-Orumlu, Makbule Asikoglu, PP36 Outfits of Tracerlan FXC-PRO for 11C-Labeling, Arponen Eveliina, Helin Semi, Saarinen Timo, Vauhkala Simo, Kokkomäki Esa, Lehikoinen Pertti, PP37 Microfluidic synthesis of ω-[18F]fluoro-1-alkynes, Mariarosaria De Simone, Giancarlo Pascali, Ludovica Carzoli, Mauro Quaglierini, Mauro Telleschi, Piero A. Salvadori, PP38 Automated 18F-flumazenil production using chemically resistant disposable cassettes, Phoebe Lam, Martina Aistleitner, Reinhard Eichinger, Christoph Artner, PP39 The effect of the eluent solutions (TBAHCO3, Kryptand K2.2.2) on the radiochemical yields of 18F-Fluoromethylcholine, Surendra Nakka, Hemantha Kumara MC, Al-Qahtani Mohammed, PP40 [68Ga]Radiolabeling of short peptide that has a PET imaging potentials, Al-Qahtani, Mohammed, Al-Malki, Yousif, PP41 Is validation of radiochemical purity analysis in a public hospital in a developing country possible?, N Mambilima, SM Rubow, PP42 Improved automated radiosynthesis of [18F]FEPPA, N. Berroterán-Infante, M. Hacker, M. Mitterhauser, W. Wadsak, PP43 Synthesis and initial evaluation of Al18F-RESCA1-TATE for somatostatin receptor imaging with PET, Uta Funke, Frederik Cleeren, Joan Lecina, Rodrigo Gallardo, Alfons M. Verbruggen, Guy Bormans, PP44 Radiolabeling and SPECT/CT imaging of different polymer-decorated zein nanoparticles for oral administration, Rocío Ramos-Membrive, Ana Brotons, Gemma Quincoces, Laura Inchaurraga, Inés Luis de Redín, Verónica Morán, Berta García-García, Juan Manuel Irache, Iván Peñuelas, PP45 An analysis of the quality of 68Ga-DOTANOC radiolabelling over a 3 year period, Trabelsi, M., Cooper M.S., PP46 In vivo biodistribution of adult human mesenchymal stem cells I (MSCS-ah) labeled with 99MTC-HMPAO administered via intravenous and intra-articular in animal model. Preliminary results, Alejandra Abella, Teodomiro Fuente, Antonio Jesús Montellano, Teresa Martínez, Ruben Rabadan, Luis Meseguer-Olmo, PP47 Synthesis of [18F]F-exendin-4 with high specific activity, Lehtiniemi P, Yim C, Mikkola K, Nuutila P, Solin O, PP48 Experimental radionuclide therapy with 177Lu-labelled cyclic minigastrin and human dosimetry estimations, von Guggenberg E, Rangger C, Mair C, Balogh L, Pöstényi Z, Pawlak D, Mikołajczak R, PP49 Synthesis of radiopharmaceuticals for cell radiolabelling using anion exchange column, Socan A, Kolenc Peitl P, Krošelj M, Rangger C, Decristoforo C, PP50 [68Ga]peptide production on commercial synthesiser mAIO, Collet C., Remy S., Didier R,Vergote T.,Karcher G., Véran N., PP51 Dry kit formulation for efficient radiolabeling of 68Ga-PSMA, D. Pawlak, M. Maurin, P. Garnuszek, U. Karczmarczyk, R. Mikołajczak, PP52 Development of an experimental method using Cs-131 to evaluate radiobiological effects of internalized Auger-electron emitters, Pil Fredericia, Gregory Severin, Torsten Groesser, Ulli Köster, Mikael Jensen, PP53 Preclinical comparative evaluation of NOTA/NODAGA/DOTA CYCLO-RGD peptides labelled with Ga-68, R. Leonte, F. D. Puicea, A. Raicu, E. A. Min, R. Serban, G. Manda, D. Niculae, PP54 Synthesizer- and Kit-based preparation of prostate cancer imaging agent 68Ga-RM2, Marion Zerna, Hanno Schieferstein, Andre Müller, Mathias Berndt, PP55 Synthesis of pancreatic beta cell-specific [18F]fluoro-exendin-4 via strain-promoted aza-dibenzocyclooctyne/azide cycloaddition, Cheng-Bin Yim, Kirsi Mikkola, Pirjo Nuutila, Olof Solin, PP56 Automated systems for radiopharmacy, D. Seifert, J. Ráliš, O. Lebeda, PP57 Simple, suitable for everyday routine use quality control method to assess radionuclidic purity of cyclotron-produced 99mTc, Svetlana V. Selivanova, Helena Senta, Éric Lavallée, Lyne Caouette, Éric Turcotte, Roger Lecomte, PP58 Effective dose estimation using Monte Carlo simulation for patients undergoing radioiodine therapy, Marina Zdraveska Kochovska, Emilija Janjevik Ivanovska, Vesna Spasic Jokic, PP59 Chemical analysis of the rituximab radioimmunoconjugates in lyophilized formulations intended for oncological applications, Darinka Gjorgieva Ackova, Katarina Smilkov, Petre Makreski, Trajče Stafilov, Emilija Janevik-Ivanovska, PP61 The need and benefits of established radiopharmacy in developing African countries, Aschalew Alemu, Joel Munene Muchira, David Mwanza Wanjeh, Emilija Janevik-Ivanovska, PP62 University Master Program of Radiopharmacy – step forward for Good Radiopharmacy Education, Emilija Janevik-Ivanovska, Zoran Zdravev, Uday Bhonsle, Osso Júnior João Alberto, Adriano Duatti, Bistra Angelovska, Zdenka Stojanovska, Zorica Arsova Sarafinovska, Darko Bosnakovski, Darinka Gorgieva-Ackova, Katarina Smilkov, Elena Drakalska, Meera Venkatesh, Rubin Gulaboski, PP63 Synthesis and preclinical validations of a novel 18F-labelled RGD peptide prepared by ligation of a 2-cyanobenzothiazole with 1,2-aminothiol to image angiogenesis., Didier J. Colin, James A. H. Inkster, Stéphane Germain, Yann Seimbille

Gadolinium-conjugated dendrimer nanoclusters (DNCs) are a promising platform for the early detection of disease; however, their clinical utility is potentially limited due to safety concerns related to nephrogenic systemic fibrosis (NSF). In this paper, biodegradable DNCs were prepared with polydisulfide linkages between the individual dendrimers to facilitate excretion. Further, DNCs were labeled with premetalated Gd chelates to eliminate the risk of free Gd becoming entrapped in dendrimer cavities. The biodegradable polydisulfide DNCs possessed a circulation half-life of1.6 h in mice and produced significant contrast enhancement in the abdominal aorta and kidneys for as long as 4 h. The DNCs were reduced in circulation as a result of thiol-disulfide exchange, and the degradation products were rapidly excreted via renal filtration. These agents demonstrated effective and prolonged in vivo contrast enhancement and yet minimized Gd tissue retention. Biodegradable polydisulfide DNCs represent a promising biodegradable macromolecular MRI contrast agent for magnetic resonance angiography and can potentially be further developed into target-specific MRI contrast agents.

Methodology for site-specific modification and chelate conjugation of a cyclic RGD (cRGD) peptide for the preparation of a radiotracer molecular imaging agent suitable for detecting α(v)β(3) integrin is described. The method involves functionalizing the peptide with an aldehyde moiety and conjugation to a 1,4,7,10-tetraazacyclododecane-N,N',N″,N‴-tetraacetic acid (DOTA) derivative that possesses an aldehyde reactive aminooxy group. The binding assay of the (111)In-labeled peptide conjugate with α(v)β(3) integrin showed 60% bound when four equivalents of the integrin was added, a reasonable binding affinity for a mono-valent modified RGD peptide.

Integrins are a family of transmembrane glycoproteins with associated α and β subunits forming 25 unique heterodimers that facilitate adhesion and migration of cells on the extracellular matrix proteins found in intercellular spaces and basement membranes.1 One of these integrins, αvβ3 integrin, interacts with vitronectin, fibronectin, fibrinogen, thrombospondin, collagen, laminin and von Willebrand factor. This integrin is over-expressed in tumor induced angiogenic vessels and in various human tumors, but is found at low levels on epithelial and endothelial cells. It is therefore a widely recognized target for the development of molecular probes for imaging angiogenesis and cancer therapy. Towards this end, the tumor imaging capability of several RGD peptides that act as αvβ3 integrin antagonists has been demonstrated by several research groups. Additionally, several of these peptides have been shown to inhibit tumor angiogenesis and interrupt metastasis in many models.2–4 There is growing interest in peptidomimetic αvβ3 integrin antagonists composed of a stable core scaffold with basic and acidic groups that mimic the guanidine and carboxylate pharmacophore of RGD peptides. Peptidomimetics tend to have higher activity, specificity and longer duration of action compared to the peptides. One such peptidomimetic αvβ3 integrin antagonist, 4-[2-(3,4,5,6-tetrahydropyrimidine-2-ylamino)ethyloxy]benzoyl-2-aminoethylsulfonyl-amino-β-alanine (IA) was synthesized by Hood et al.5 Subsequent, modification of IA to the corresponding carbamate derivatives by the Danthi group resulted in 4-[2-(3,4,5,6-tetrahydropyrimidine-2-ylamino)ethyloxy]benzoyl-2-[N-(3-amino-neopenta-1-carbamyl)]-aminoethylsulfonyl-amino-β-alanine (IAC), with a binding affinity 20 times greater than that of IA.6 A SPECT (single photon emission computed tomography) imaging study with 111In-DOTA-Bz-SCN- IAC was also performed and tumor was clearly visualized at 4 h p.i.7111In-DOTA-Bz-SCN- IAC was prepared using the bifunctional chelate DOTA-Bz-SCN which differs from the DOTA-GA described in this study. Clinically, SPECT and PET (positron emission tomography) play significant roles allowing noninvasive imaging of internal physiological and biochemical function and pathologies in vivo. While PET is more expensive, it has significant advantages over SPECT with respect to its ability to better quantify images. Of metallic radionuclides currently being investigated for PET applications, gallium-68 (68Ga) has grown in popularity.8, 9 The popularity of 68Ga stems from the ease of on site production from a long lived generator system (68Ge/68Ga) rather than a cyclotron, and automation for incorporation into radiolabeled compounds.10 The 67.7 min half-life of 68Ga is an appropriate match to the biological half-lives of peptides. Gallium(III) typically binds with chelates possessing multiple anionic oxygen donors preferring a coordination number of six in an octahedral geometry. Fitting these preferences, the macrocyclic ligand, 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA), is well established as forming very stable complexes with a wide variety of metals, Ga(III) being one of them.11 Several NOTA derivatives have been reported (Figure 1) for use in the radiolabeling of proteins and peptides. Recently, Knetsch et al reported a 68Ga-labeled NODA-GA-conjugated RGD peptide ([68Ga]NODAGA-RGD) that showed better tumor to blood ratio in vivo than the corresponding [68Ga]DOTA-RGD derivative.12 Figure 1 Structures of NOTA derivatives. 7-(5-Maleimido-1-ethoxycarbonylphenyl)-1,4,7-triazacyclononane-1,4-diylacetic acid (1), 2-(4-Aminobutyl)-1,4,7-triazacyclononane-1,4,7-triyltriacetic acid (2), nNOTA (3), p-SCN-Bn-NOTA (4), NETA (5), and NODA-GA(tBu)3 ( ... While interest in 68Ga for PET imaging is currently significant, there are Pb(II) isotopes that have also been of interest for biomedical applications. Specifically, 203Pb and 212Pb are radiometals possessing favorable properties for use in nuclear medicine for potential diagnostic and therapeutic applications, respectively.13–21203Lead (t1/2 = 51.9 h) emits a γ-ray (279 keV) that is ideal for single photon emission computed tomography (SPECT) imaging and is suitable for pharmacokinetic and pharmacodynamic tracer studies. In addition, 203Pb can serve as one half of a potential matched-pair of radioisotopes when combined with 212Pb for therapeutic applications.212 Lead (t1/2 = 10.6 h) has been studied as an `in vivo generator' of 212Bi (t1/2 = 60 min) to overcome the short half-life of that daughter isotope. The macrocyclic polyaminocarboxylate chelate DOTA, (1,4,7,10-tetraazacyclododecane-N,N',N”,N”'-tetraacetic acid labeled with 212Pb provides a complex that is adequately stable in vivo to sequester the radionuclide.17 The Macke group in Switzerland have synthesized a DOTA derivative analogous to NOTA-GA, , 1-(1-carboxy-3-carbotertbutoxymethyl)-1,4,7,10-tetraazacyclododecane (DOTA-GA(tBu)4).22 The DOTA-GA(tBu)4 affords four intact carboxylic acid functional groups with a free carboxylate side chain ready for conjugation to the N-terminus of peptides which makes it useful for biomedical applications. In the present study, the objective was to move beyond the use of RGD peptides as delivery vectors to the various integrin targets and explore the utility of IAC for such applications. 68Gallium labeling was investigated for PET applications using NODA-GA and 67Ga as a surrogate for 68Ga, and 203Pb for SPECT imaging using DOTA-GA. To this end, IAC was successfully conjugated to NODAGA (Scheme 1) and DOTA-GA (Scheme 2) and the conjugates were radiolabeled with 111In or 67Ga for the NODA-GA conjugate and 203Pb for the DOTA-GA conjugate. In brief, NODA-GA(tBu)3 or DOTAGA(tBu)4, N-hydroxysuccinimide, and EDC were dissolved in dichloromethane and the reaction mixture was stirred for 24 h. The mixture was extracted with saturated NaCl solution, 5% NaHCO3, and saturated NaCl again. The organic layer was dried over MgSO4, filtered, and dried under vacuum resulting in the formation of yellowish oils 2 or 5. The IAC and 2 or 5 were combined in anhydrous DMF and diisopropylethylamine was added to the mixture which was then stirred overnight at room temperature. Reverse-phase HPLC purification followed by TFA deprotection yielded 1 or 4, respectively.23, 24 To evaluate the radiolabeling efficiency of the NODA-GA and DOTA-GA conjugates,111In, 67Ga and 203Pb were employed to demonstrate facile formation of complexes with these radionuclides. The NODA-GA conjugate 1 was efficiently radiolabeled (> 90 %) with 111In and 67Ga within 30 min (Fig. 2A and 2B, respectively). The radiolabeling of the DOTA-GA conjugate 4 with 203Pb was equally efficient (Fig. 2C). Non-radioactive Ga(III)-1 and Pb(II)-4 were also synthesized in order to characterize the radiolabeled 67Ga and 203Pb complexes.25, 26 Figures 3 and ​and44 demonstrate HPLC profiles of the mixture containing both Ga(III)-1 and 67Ga-1; and Pb(II)-4 and 203Pb-4, respectively. Figure 2 Radio-HPLC profiles of 111In-1, A; 67Ga-1, B; and 203Pb-4, C and Figure 3 HPLC profiles of Ga(III)-1 (top) and 67Ga-1 (bottom) Figure 4 HPLC profiles of Pb(II)-4 (top) and 203Pb-4 (bottom). Scheme 1 Synthesis of compound 1. Scheme 2 Synthesis of compound 4. A radioimmunoassay was performed to assess the binding ability of the radiolabeled NODA-GA and DOTA-GA conjugates with αvβ3 integrin. The 111In-labeled 1 (2 × 106 cpm, 0.47 μM), 67Ga-labeled 1 (5 × 105 cpm, 0.45 μM) or 203Pb-labeled 4 (3 × 105 cpm, 0.5 μM) was incubated with 0, 0.5, 1.0 and 2.0 μM of purified human αvβ3 integrin (MW 237,000) in a total volume of 25 μL PBS for 3 h at 37 °C. For non-specific binding, excess IAC (20 μM) was added to the reaction mixture to block binding. The reaction mixture was then separated on a 10 mL Sephadex G50 column using PBS as eluent. Fractions (0.5 mL) were collected and subsequently counted in a γ-counter. As indicated in Table 1, the labeled conjugates bound the integrin to varying degrees. The binding of 111In-1 was greatest followed by 67Ga-1 and then 203Pb-4. In addition, binding was blocked ~95% by the addition of a 10 to 20-fold molar excess of the cold IAC to the reaction solution indicating specific binding of the labeled conjugates. Furthermore, it is worth noting that the reactivity of the 111In-1 with αvβ3 integrin (88 %) is higher than that reported for 111In-DOTA-IAC (72 %).7 Table 1 Binding of 111In-1, 67Ga-1 and 203Pb-4 to purified αvβ3 integrin. In conclusion, the peptidomimetic αvβ3 integrin antagonist (IAC) was conjugated to NODA-GA and DOTA-GA and successfully radiolabeled with 111In, 67Ga and 203Pb. This promising preliminary data is fueling further investigation of NODA-GA-IAC and DOTA-GA-IAC conjugates for targeting tumor associated angiogenesis and αvβ3 integrin positive tumors using PET and SPECT imaging. Other potential applications include the use of radionuclides such as 90Y, 177Lu and 212Pb for radiotherapy.

Studies from this laboratory have demonstrated the potential of targeting HER2 for therapeutic and imaging applications with medically relevant radionuclides. To expand the repertoire of trastuzumab as a radioimmunoconjugate (RIC) vector, use of (177)Lu was investigated. The combination of a 6.7 d half-life, lower energy β(-)-emissions (500 keV max; 130 keV ave), and an imagable γ-emission make (177)Lu an attractive candidate for radioimmunotherapy (RIT) regimens for treatment of larger tumor burdens not possible with α-zparticle radiation. Radiolabeling trastuzumab-CHX-A"-DTPA with (177)Lu was efficient with a specific binding of 60.8 ± 6.8% with HER2 positive SKOV-3 cells. Direct quantitation of tumor targeting and normal tissue uptake was performed with athymic mice bearing subcutaneous and intraperitoneal LS-174T xenografts; a peak tumor %ID/g of 24.70 ± 10.29 (96 h) and 31.70 ± 16.20 (72 h), respectively, was obtained. Normal tissue uptake of the RIC was minimal. Tumor targeting was also demonstrated by γ-scintigraphy. A therapy study administering escalating doses of (177)Lu-trastuzumab to mice bearing three day LS-174T i.p. xenografts established the effective therapeutic dose of i.p. administered (177)Lu-trastuzumab at 375 μCi with a median survival of 124.5 d while a median survival of 10 d was noted for the control (untreated) group. In conclusion, trastuzumab radiolabeled with (177)Lu has potential for treatment of disseminated, HER2 positive, peritoneal disease.

Herein we report the preparation along with the in vivo and in vitro MRI characterization of two generation four and five cystamine core dendrimers loaded with thirty and fifty-eight derivatized Gd-DOTA (G4SS30, G5SS58) respectively. Likewise the development and characterization of two half-dendrimers conjugated to the F(ab')(2) fragment of the monoclonal antibody (mAb) panitumumab functionalized with a maleimide conjugation functional group site (Ab-(G4S15)(4), Ab-(G5S29)(4)) are also described. The in vitro molar relaxivity of the Ab-(G4S15)(4) conjugate, measured at pH 7.4, 22 °C, and 3T showed a moderate increase in relaxivity as compared to Magnevist (6.7 vs 4.0 mM(-1) s(-1)) while the Ab-(G5S29)(4) conjugate was 2-fold higher (9.1 vs 4.0 mM(-1) s(-1)). The data showed that only a high injection dose (0.050 mmol Gd(3+)/kg) produced a detectable contrast enhanced contrast for the Ab-(G4S15)(4) conjugate while a lower dose (0.035 mmol Gd(3+)/kg) was sufficient for the Ab-(G5S29)(4) conjugate. The antibody-SMCC conjugate was purified by a Sephadex G-100 column, and the antibody-dendrimer-based agents were purified by spin filtration using a Centricon filter (50,000 MCO). The protein assay coupled with cysteine and Ellman's assay indicated an antibody to dendrimer ratio of 1:4. The in vivo blood clearance half-lives of the four agents measured at the jugular vein were ~12-22 min.

Development of targeted radionuclide therapy with (90)Y labeled antibodies and peptides has gained momentum in the past decade due to the successes of (90)Y-ibritumomab tiuxetan and (90)Y-DOTA-Phe(1)-Tyr(3)-octreotide in treatment of cancer. (90)Y is a pure β(-)-emitter and cannot be imaged for patient-specific dosimetry which is essential for pre-therapeutic treatment planning and accurate absorbed dose estimation in individual patients to mitigate radiation related risks. This review article describes the utility of (86)Y, a positron emitter (33%) with a 14.7-h half-life that can be imaged by positron emission tomography and used as an isotopically matched surrogate radionuclide for (90)Y radiation doses estimations. This review discusses various aspects involved in the development of (86)Y labeled radiopharmaceuticals with the specific emphasis on the radiochemistry and biological applications with antibodies and peptides.

The advent of molecular targeted therapies offers the hope of therapeutic advance in the fight against cancer. However, this hope is tempered by recent findings that certain targeted therapies may have unique side effects. The Hedgehog (HH) pathway is a potential target for treatment of several cancers, including basal cell carcinoma and a subset of medulloblastoma. Recent clinical trials in adults have shown responses to HH pathway inhibition in both basal cell carcinoma and medulloblastoma. However, concerns have been raised about the use of HH pathway inhibitors in children because of the role the HH pathway plays in development. Indeed, young mice treated with the HH pathway inhibitor HhAntag developed severe bone defects, including premature differentiation of chondrocytes, thinning of cortical bone, and fusion of the growth plate. In an effort to lessen the severity of bone defects caused by HhAntag, we treated young mice simultaneously with HhAntag and parathyroid hormone–related protein (PTHrP), which functions downstream of Indian Hedgehog to maintain chondrocytes in a proliferative state. The results show that whereas treatment with PTHrP causes a significant increase in trabecular bone, it does not prevent fusion of the growth plate induced by HhAntag.

This study aims to develop and characterize the trafficking of a dual-modal agent that identifies primary draining or sentinel lymph node (LN). Herein, a dual-reporting silica-coated iron oxide nanoparticle (SCION) is developed. Nude mice were imaged by magnetic resonance (MR) and optical imaging and axillary LNs were harvested for histological analysis. Trafficking through lymphatics was observed with intravital and ex vivo confocal microscopy of popliteal LNs in B6-albino, CD11c-EYFP, and lys-EGFP transgenic mice. In vivo, SCION allows visualization of LNs. The particle’s size and surface functionality play a role in its passive migration from the intradermal injection site and its minimal uptake by CD11c+ dendritic cells and CD169+ and lys+ macrophages. After injection, SCION passively migrates to LNs without macrophage uptake and then can be used to image LN(s) by MRI and fluorescence. Thus, SCION can potentially be developed for use in sentinel node resections or for intralymphatic drug delivery.

Aim: Imaging of the lymphatic system is critical in preoperative planning of resections of complex lymphatic malformations. However, safe, effective imaging methods with sufficient resolution to identify the lymphatics have been lacking. In this study, we demonstrate the use of gadolinium-labeled dendrimers to image the lymphatics in small and large animal models during magnetic resonance lymphangiography. Methods: Polyamidoamine G6-Gd_1B4M_N-hydroxysuccinimide was synthesized and administered intradermally in the extremities of normal mice and pigs at several doses. Results: The lymphatics were well demonstrated in both animal models and there was rapid uptake in the deep lymphatic system, including the thoracic duct. A significant dose reduction was achieved (1 µmol Gd/kg) in the 35-kg pig compared with mice, while still producing excellent results. No toxicity was observed and only minor inflammatory changes were observed at the injection site 30 days later. Conclusion: We demonstrate that a low dose of a macromolecular magnetic resonance contrast agent can provide rapid imaging of the deep lymphatic system in both small and large animals. This data provides a basis to consider a similar agent in clinical trials.

The potential of the HER2-targeting antibody trastuzumab as a radioimmunoconjugate useful for both imaging and therapy was investigated. Conjugation of trastuzumab with the acyclic bifunctional chelator CHX-A"-DTPA yielded a chelate:protein ratio of 3.4 ± 0.3; the immunoreactivity of the antibody unaffected. Radiolabeling was efficient, routinely yielding a product with high specific activity. Tumor targeting was evaluated in mice bearing subcutaneous (s.c.) xenografts of colorectal, pancreatic, ovarian, and prostate carcinomas. High uptake of the radioimmunoconjugate, injected intravenously (i.v.), was observed in each of the models, and the highest tumor %ID/g (51.18 ± 13.58) was obtained with the ovarian (SKOV-3) tumor xenograft. Specificity was demonstrated by the absence of uptake of 111In-trastuzumab by melanoma (A375) s.c. xenografts and 111In-HuIgG by s.c. LS-174T xenografts. Minimal uptake of i.v. injected 111In-trastuzumab in normal organs was confirmed in non-tumor-bearing mice. The in vivo behavior of 111In-trastuzumab in mice bearing intraperitoneal (i.p.) LS-174T tumors resulted in a tumor %ID/g of 130.85 ± 273.34 at 24 h. Visualization of tumor, s.c. and i.p. xenografts, was achieved by γ-scintigraphy and PET imaging. Blood pool was evident as expected, but cleared over time. The blood pharmacokinetics of i.v. and i.p. injected 111In-trastuzumab was determined in mice with and without tumors. The data from these in vitro and in vivo studies supported advancement of radiolabeled trastuzumab into two clinical studies, a Phase 0 imaging study in the Molecular Imaging Program of the National Cancer Institute and a Phase 1 radioimmunotherapy study at the University of Alabama.

Magnetic resonance imaging (MRI) is a powerful imaging modality that can provide an assessment of function or molecular expression in tandem with anatomic detail. Over the last 20–25 years, a number of gadolinium-based MR contrast agents have been developed to enhance signal by altering proton relaxation properties. This review explores a range of these agents from small molecule chelates, such as Gd-DTPA and Gd-DOTA, to macromolecular structures composed of albumin, polylysine, polysaccharides (dextran, inulin, starch), poly(ethylene glycol), copolymers of cystamine and cystine with GD-DTPA, and various dendritic structures based on polyamidoamine and polylysine (Gadomers). The synthesis, structure, biodistribution, and targeting of dendrimer-based MR contrast agents are also discussed.

In this report we directly compare the in vivo and in vitro MRI properties of gadolinium–dendrimer conjugates of derivatized acyclic diethylenetriamine- N , N ′, N ′, N ″, N ″-pentaacetic acid (1B4M-DTPA) and macrocyclic 1,4,7,10-tetraazacyclododecane- N , N ′, N ″, N ‴-tetraacetic acid ( C -DOTA). The metal–ligand chelates were pre-formed in alcohol prior to conjugation to the generation 4 PAMAM dendrimer (G4D), and the dendrimer-based agents were purified by Sephadex® G-25 column. The analysis and SE-HPLC data indicated chelate to dendrimer ratios of 30:1 and 28:1, respectively. Molar relaxivity measured at pH 7.4, 22 °C, and 3T are comparable (29.5 vs 26.9 mM −1 s −1 ), and both conjugates are equally viable as MRI contrast agents based on the images obtained. The macrocyclic agent however exhibits a faster rate of clearance in vivo ( t 1/2 = 16 vs 29 min). Our conclusion is that the macrocyclic-based agent is the more suitable agent for in vivo use for these reasons combined with kinetic inertness associated with the Gd(III) DOTA complex stability properties.

This report presents the preparation and characterization of three [Gd-C-DOTA](-1)-dendrimer assemblies by way of analysis, NMRD spectroscopy, and photon correlation spectroscopy (PCS). The metal-ligand chelates were preformed in alcohol media prior to conjugation to generation 4, 5, and 6 PAMAM dendrimers. The dendrimer-based agents were purified by Sephadex G-25 column chromatography. The combustion analysis, SE-HPLC, and UV-vis data indicated chelate to dendrimer ratios of 28:1, 61:1 and 115:1, respectively. Molar relaxivity measured at pH 7.4, 22 degrees C, and 3 T (29.6, 49.8, and 89.1 mM(-1) s(-1)) indicated the viability of conjugates as MRI contrast agents. 1/T(1) NMRD profiles were measured at 23 degrees C and indicated that at 22 MHz the 1/T(1) reached a plateau at 60, 85, and 140 mM(-1) s(-1) for the generation 4, 5, and 6 dendrimer conjugates, respectively. The PCS data showed the respective sizes of 5.2, 6.5, and 7.8 nm for G-4, 5, and 6 conjugates.

Bevacizumab is a humanized monoclonal antibody that binds to tumor-secreted vascular endothelial growth factor (VEGF)-A and inhibits tumor angiogenesis. In 2004, the antibody was approved by the US Food and Drug Administration (FDA) for the treatment of metastatic colorectal carcinoma in combination with chemotherapy. This report describes the preclinical evaluation of a radioimmunoconjugate, (86)Y-CHX-A″-DTPA-bevacizumab, for potential use in Positron Emission Tomography (PET) imaging of VEGF-A tumor angiogenesis and as a surrogate marker for (90)Y-based radioimmunotherapy. Bevacizumab was conjugated to CHX-A″-DTPA and radiolabeled with (86)Y. In vivo biodistribution and PET imaging studies were performed on mice bearing VEGF-A-secreting human colorectal (LS-174T), human ovarian (SKOV-3) and VEGF-A-negative human mesothelioma (MSTO-211H) xenografts. Biodistribution and PET imaging studies demonstrated highly specific tumor uptake of the radioimmunoconjugate. In mice bearing VEGF-A-secreting LS-174T, SKOV-3 and VEGF-A-negative MSTO-211H tumors, the tumor uptake at 3 days postinjection was 13.6 ± 1.5, 17.4 ± 1.7 and 6.8 ± 0.7 % ID/g, respectively. The corresponding tumor uptake in mice coinjected with 0.05 mg cold bevacizumab were 5.8 ± 1.3, 8.9 ± 1.9 and 7.4 ± 1.0 % ID/g, respectively at the same time point, demonstrating specific blockage of the target in VEGF-A-secreting tumors. The LS-174T and SKOV3 tumors were clearly visualized by PET imaging after injecting 1.8-2.0 MBq (86)Y-CHX-A″-DTPA-bevacizumab. Organ uptake quantified by PET closely correlated (r(2) = 0.87, p = 0.64, n = 18) to values determined by biodistribution studies. This preclinical study demonstrates the potential of the radioimmunoconjugate, (86)Y-CHX-A″-DTPA-bevacizumab, for noninvasive assessment of the VEGF-A tumor angiogenesis status and as a surrogate marker for (90)Y-CHX-A″-DTPA-bevacizumab radioimmunotherapy.

The studies described here are the first to evaluate the in vitro and in vivo properties of (111)In-CHX-A''-panitumumab for radioimmunotherapy (alpha- and beta(-)-emitters) and radioimmunoimaging (single photon emission computed tomography and positron emission tomography).Twenty-seven human carcinoma cell lines were analysed for expression of epidermal growth factor receptors by flow cytometry. Panitumumab was conjugated with CHX-A''-DTPA (diethylenetriamine-pentaacetic acid) and radiolabelled with (111)In. Immunoreactivity of the CHX-A''-DTPA-panitumumab and (111)In-CHX-A''-DTPA-panitumumab was evaluated by radioimmunoassays. Tumour targeting was determined in vivo by direct quantitation of tumour and normal tissues and by gamma-scintigraphy.For 26 of 27 human tumour cell lines, 95% of the cells expressed epidermal growth factor receptors over a range of intensity. Immunoreactivity of panitumumab was retained after modification with CHX-A''-DTPA. Radiolabelling of the immunoconjugate with (111)In was efficient with a specific activity of 19.5 +/- 8.9 mCi.mg(-1) obtained. Immunoreactivity and specificity of binding of the (111)In-panitumumab was shown with A431 cells. Tumour targeting by (111)In-panitumumab was demonstrated in athymic mice bearing A431, HT-29, LS-174T, SHAW or SKOV-3 s.c. xenografts with little uptake observed in normal tissues. The (111)In-panitumumab was also evaluated in non-tumour-bearing mice. Pharmacokinetic studies compared the plasma retention time of the (111)In-panitumumab in both non-tumour-bearing and A431 tumour-bearing mice. Tumour targeting was also visualized by gamma-scintigraphy.Panitumumab can be efficiently radiolabelled with (111)In with high labelling yields. Based on the efficiency in tumour targeting and low normal tissue uptake, panitumumab may be an effective targeting component for radioimmunodiagnostic and radioimmunotherapeutic applications.

Two novel imaging agents trastuzumab-Cy5.5-CHX-A''1 and cetuximab-Cy7-CHX-A''2, bearing both a chelating moiety (CHX-A'') for sequestering metallic radionuclides ((86)Y or (111)In) and the near infrared dye Cy5.5/Cy7, were prepared by a novel modular synthetic strategy as examples of dual-labeled, antibody-based imaging probe library. Fluorescent microscopy illustrated that 1 and 2 strongly bind to HER2-expressing cancer cells (e.g., NIH3T3-HER2(+), SKOV-3) and to EGFR-expressing cancer cells (e.g., A431), respectively, thereby demonstrating that the functionality of the targeting moiety is conserved. Hence, the described novel synthesis strategy can be applied to engineer other tumor-targeted monoclonal antibody based probes for multimodality imaging.