Positron Emission Tomography Imaging of Infection Using a Nitro-Prodrug Analogue of 2-[F]F--Aminobenzoic Acid.

Deep-seated bacterial infections caused by pathogens such as are difficult to diagnose and treat and are thus a major threat to human health. In previous work we demonstrated that positron emission tomography (PET) imaging with 2-[F]F--aminobenzoic acid (2-[F]F-PABA) could noninvasively identify, localize, and monitor infection with excellent sensitivity and specificity in a rodent soft tissue infection model. However, 2-[F]F-PABA is rapidly N-acetylated and eliminated, and in an attempt to improve radiotracer accumulation in bacteria we adopted a prodrug strategy in which the acid was protected by an ester and the amine was replaced with a nitro group.

Complement factor H-deficient mice develop spontaneous hepatic tumors.

Hepatocellular carcinoma (HCC) is difficult to detect, carries a poor prognosis, and is one of few cancers with an increasing yearly incidence. Molecular defects in complement factor H (CFH), a critical regulatory protein of the complement alternative pathway (AP), are typically associated with inflammatory diseases of the eye and kidney. Little is known regarding the role of CFH in controlling complement activation within the liver.

Positron Emission Tomography Imaging with 2-[F]F- p-Aminobenzoic Acid Detects Staphylococcus aureus Infections and Monitors Drug Response.

Staphylococcus aureus is the leading cause of life-threatening infections, frequently originating from unknown or deep-seated foci. Source control and institution of appropriate antibiotics remain challenges, especially with infections due to methicillin-resistant S. aureus (MRSA).

GABA Receptor Availability Changes Underlie Symptoms in Isolated Cervical Dystonia.

GABA receptor availability changes within sensorimotor regions have been reported in some isolated forms of dystonia. Whether similar abnormalities underlie symptoms in cervical dystonia is not known. In the present study, a total of 15 cervical dystonia patients and 15 age- and sex-matched controls underwent C-flumazenil PET/CT scanning.

I-124 codrituzumab imaging and biodistribution in patients with hepatocellular carcinoma.

Background: I-124 codrituzumab (aka GC33), an antibody directed at Glypican 3, was evaluated in patients with hepatocellular carcinoma (HCC). Fourteen patients with HCC underwent baseline imaging with I-124 codrituzumab (~ 185 MBq, 10 mg). Seven of these patients undergoing sorafenib/immunotherapy with 2.

The biodistribution of 5-[18F]fluoropyrazinamide in Mycobacterium tuberculosis-infected mice determined by positron emission tomography.

5-[18F]F-pyrazinamide (5-[18F]F-PZA), a radiotracer analog of the first-line tuberculosis drug pyrazinamide (PZA), was employed to determine the biodistribution of PZA using PET imaging and ex vivo analysis. 5-[18F]F-PZA was synthesized in 60 min using a halide exchange reaction. The overall decay-corrected yield of the reaction was 25% and average specific activity was 2.

Phase Ib study of codrituzumab in combination with sorafenib in patients with non-curable advanced hepatocellular carcinoma (HCC).

Purpose: Codrituzumab, a humanized antibody against glypican-3, is highly expressed in HCC. A phase I study evaluated the combination with sorafenib in HCC.

Patients And Methods: In a 3 + 3 design, codrituzumab was given intravenously in various doses with sorafenib 400 mg twice daily to patients with advanced HCC, age ≥18, ECOG 0-1, Child-Pugh A and B7, adequate organ functions, and no prior systemic therapy, with tumor assessment by RECIST 1.

Utility of positron emission tomography for drug development for heart failure.

Only about 1 in 5,000 investigational agents in a preclinical stage acquires Food and Drug Administration approval. Among many reasons for this includes an inefficient transition from preclinical to clinical phases, which exponentially increase the cost and the delays the process of drug development. Positron emission tomography (PET) is a nuclear imaging technique that has been used for the diagnosis, risk stratification, and guidance of therapy.

Copper-64 trastuzumab PET imaging: a reproducibility study.

Background: The current study aims to assess the safety, pharmacokinetics, feasibility, and reproducibility of immunoPET imaging with copper-64 (64Cu) trastuzumab.

Methods: An IV injection of 296-370 MBq/5 mg 64Cu-trastuzumab was administered between 1 to 4 hours after routine trastuzumab treatment. Whole-body PET scans were performed immediately post-injection and at 24 hours post-injection.

Radiosynthesis of the iodine-124 labeled Hsp90 inhibitor PU-H71.

Heat shock protein 90 (Hsp90) is an ATP dependent molecular chaperone protein whose function is critical for maintaining several key proteins involved in survival and proliferation of cancer cells. PU-H71 (1), is a potent purine-scaffold based ATP pocket binding Hsp90 inhibitor which has been shown to have potent activity in a broad range of in vivo cancer models and is currently in Phase I clinical trials in patients with advanced solid malignancies, lymphomas, and myeloproliferative neoplasms. In this report, we describe the radiosynthesis of [(124)I]-PU-H71(5); this was synthesized from the corresponding Boc-protected stannane precursor 3 by iododestannylation with [(124)I]-NaI using chloramine-T as an oxidant for 2 min, followed by Boc deprotection with 6 N HCl at 50 °C for 30 min to yield the final compound.

Theranostic pretargeted radioimmunotherapy of colorectal cancer xenografts in mice using picomolar affinity ⁸⁶Y- or ¹⁷⁷Lu-DOTA-Bn binding scFv C825/GPA33 IgG bispecific immunoconjugates.

Purpose: GPA33 is a colorectal cancer (CRC) antigen with unique retention properties after huA33-mediated tumor targeting. We tested a pretargeted radioimmunotherapy (PRIT) approach for CRC using a tetravalent bispecific antibody with dual specificity for GPA33 tumor antigen and DOTA-Bn-(radiolanthanide metal) complex.

Methods: PRIT was optimized in vivo by titrating sequential intravenous doses of huA33-C825, the dextran-based clearing agent, and the C825 haptens (177)Lu-or (86)Y-DOTA-Bn in mice bearing the SW1222 subcutaneous (s.

PET-based compartmental modeling of (124)I-A33 antibody: quantitative characterization of patient-specific tumor targeting in colorectal cancer.

Purpose: The molecular specificity of monoclonal antibodies (mAbs) directed against tumor antigens has proven effective for targeted therapy of human cancers, as shown by a growing list of successful antibody-based drug products. We describe a novel, nonlinear compartmental model using PET-derived data to determine the "best-fit" parameters and model-derived quantities for optimizing biodistribution of intravenously injected (124)I-labeled antitumor antibodies.

Methods: As an example of this paradigm, quantitative image and kinetic analyses of anti-A33 humanized mAb (also known as "A33") were performed in 11 colorectal cancer patients.

Severe pulmonary hypertension is associated with altered right ventricle metabolic substrate uptake.

In severe pulmonary hypertension (SPH), prior studies have shown an increase in right ventricle (RV) uptake of glucose, but it is unclear whether there is a change in the relative utilization of fatty acids. We hypothesized that in the RV in SPH, as in left ventricular (LV) failure, there is altered substrate utilization, with increased glucose uptake and decreased fatty acid uptake. SPH was induced in rats by treatment with the VEGF receptor inhibitor SU5416 and 3 wk of hypoxia (10% FiO2 ), followed by an additional 4 wk of normoxia (SU-Hx group).

Indium 111-labeled J591 anti-PSMA antibody for vascular targeted imaging in progressive solid tumors.

Background: J591 is a monoclonal antibody that targets the external domain of the prostate-specific membrane antigen (PSMA). Besides prostate cancer cells, it also targets the neovasculature of non-prostate solid tumors. We provide an analysis of the antibody mass-dose dependency of lesion uptake and normal tissue retention, together with an assessment of lesion detectability using (111)In-J591 imaging, compared with conventional imaging in patients with a variety of solid tumors.

Biodistribution and delivery efficiency of unmodified tumor-derived exosomes.

The use of exosomes as a drug delivery vehicle has gained considerable interest. To establish if exosomes could be utilized effectively for drug delivery, a better understanding of their in vivo fate must be established. Through comparisons to liposomal formulations, which have been studied extensively for the last thirty years, we were able to make some comprehensive conclusions about the fate of unmodified tumor-derived exosomes in vivo.

Surface functionalization of exosomes using click chemistry.

A method for conjugation of ligands to the surface of exosomes was developed using click chemistry. Copper-catalyzed azide alkyne cycloaddition (click chemistry) is ideal for biocojugation of small molecules and macromolecules to the surface of exosomes, due to fast reaction times, high specificity, and compatibility in aqueous buffers. Exosomes cross-linked with alkyne groups using carbodiimide chemistry were conjugated to a model azide, azide-fluor 545.

⁸⁹Zr-huJ591 immuno-PET imaging in patients with advanced metastatic prostate cancer.

Purpose: Given the bone tropism of prostate cancer, conventional imaging modalities poorly identify or quantify metastatic disease. (89)Zr-huJ591 positron emission tomography (PET) imaging was performed in patients with metastatic prostate cancer to analyze and validate this as an imaging biomarker for metastatic disease. The purpose of this initial study was to assess safety, biodistribution, normal organ dosimetry, and optimal imaging time post-injection for lesion detection.

Efficient 1-step radiolabeling of monoclonal antibodies to high specific activity with 225Ac for α-particle radioimmunotherapy of cancer.

Unlabelled: Targeted α-particle radiation using the radioisotope (225)Ac is a promising form of therapy for various types of cancer. Historic obstacles to the use of (225)Ac have been the difficulty in finding suitable chelators to stably attach it to targeting vehicles such as peptides and monoclonal antibodies, the low specific activities of the products, and the lack of cost-effective radiolabeling procedures. We initially solved the first problem with a procedure involving 2 chemical steps that has been used as a standard in preclinical and clinical studies.

Pilot study of 68Ga-DOTA-F(ab')2-trastuzumab in patients with breast cancer.

Objective: 68Ga-1,4,7,10-Tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA)-F(ab')2-trastuzumab [68Ga-DOTA-F(ab')2-trastuzumab] has been developed at our institution as a positron imaging reagent for assessing human epidermal growth factor receptor 2 (HER2) expression status by in-vivo imaging. Initial studies on animals demonstrated promising results in the monitoring of treatment response to heat shock protein 90-targeted drugs that inhibit the client protein HER2. We report here our initial clinical experience in the assessment of the toxicity, pharmacokinetics, biodistribution, and dosimetry profile of 68Ga-DOTA-F(ab')2-trastuzumab with PET/computed tomography using a mean of 236 MBq/5 mg administered intravenously.

Fluorine-labeled dasatinib nanoformulations as targeted molecular imaging probes in a PDGFB-driven murine glioblastoma model.

Dasatinib, a new-generation Src and platelet-derived growth factor receptor (PDGFR) inhibitor, is currently under evaluation in high-grade glioma clinical trials. To achieve optimum physicochemical and/or biologic properties, alternative drug delivery vehicles may be needed. We used a novel fluorinated dasatinib derivative (F-SKI249380), in combination with nanocarrier vehicles and metabolic imaging tools (microPET) to evaluate drug delivery and uptake in a platelet-derived growth factor B (PDGFB)-driven genetically engineered mouse model (GEMM) of high-grade glioma.

Evolution of bombesin conjugates for targeted PET imaging of tumors.

Bombesin receptors are under intense investigation as molecular targets since they are overexpressed in several prevalent solid tumors. We rationally designed and synthesized a series of modified bombesin (BN) peptide analogs to study the influence of charge and spacers at the N-terminus, as well as amino acid substitutions, on both receptor binding affinity and pharmacokinetics. This enabled development of a novel (64/67)Cu-labeled BN peptide for PET imaging and targeted radiotherapy of BN receptor-positive tumors.

Phase 1 radioimmunotherapy study with lutetium 177-labeled anti-carbonic anhydrase IX monoclonal antibody girentuximab in patients with advanced renal cell carcinoma.

Background: Patients with metastatic clear cell renal cell carcinoma (ccRCC) have a dismal prognosis. Therefore, new and less toxic treatments are needed.

Objective: We determined the maximum tolerated dose (MTD) and potential therapeutic efficacy of multiple infusions of lutetium 177 ((177)Lu)-girentuximab (cG250) on various dose levels in a phase 1 trial in patients with progressive metastasized ccRCC.

ARN-509: a novel antiandrogen for prostate cancer treatment.

Continued reliance on the androgen receptor (AR) is now understood as a core mechanism in castration-resistant prostate cancer (CRPC), the most advanced form of this disease. While established and novel AR pathway-targeting agents display clinical efficacy in metastatic CRPC, dose-limiting side effects remain problematic for all current agents. In this study, we report the discovery and development of ARN-509, a competitive AR inhibitor that is fully antagonistic to AR overexpression, a common and important feature of CRPC.

124I-huA33 antibody uptake is driven by A33 antigen concentration in tissues from colorectal cancer patients imaged by immuno-PET.

Unlabelled: The primary aim of this analysis was to examine the quantitative features of antibody-antigen interactions in tumors and normal tissue after parenteral administration of antitumor antibodies to human patients.

Methods: Humanized anti-A33 antibody (10 mg) labeled with the positron-emitting radionuclide (124)I ((124)I-huA33) was injected intravenously in 15 patients with colorectal cancer. Clinical PET/CT was performed approximately 1 wk later, followed by a detailed assay of surgically removed tissue specimens including radioactivity counting, autoradiography, immunohistochemistry, and antigen density determination.

Affinity-based proteomics reveal cancer-specific networks coordinated by Hsp90.

Most cancers are characterized by multiple molecular alterations, but identification of the key proteins involved in these signaling pathways is currently beyond reach. We show that the inhibitor PU-H71 preferentially targets tumor-enriched Hsp90 complexes and affinity captures Hsp90-dependent oncogenic client proteins. We have used PU-H71 affinity capture to design a proteomic approach that, when combined with bioinformatic pathway analysis, identifies dysregulated signaling networks and key oncoproteins in chronic myeloid leukemia.