Monitoring of cancer ferroptosis with [F]hGTS13, a system xc- specific radiotracer.

Glioblastoma multiforme (GBM) is the most common and aggressive primary brain tumor in adults, characterized by resistance to conventional therapies and poor survival. Ferroptosis, a form of regulated cell death driven by lipid peroxidation, has recently emerged as a promising therapeutic target for GBM treatment. However, there are currently no non-invasive imaging techniques to monitor the engagement of pro-ferroptotic compounds with their respective targets, or to monitor the efficacy of ferroptosis-based therapies.

An engineered NKp46 antibody for construction of multi-specific NK cell engagers.

Recent developments in cancer immunotherapy have highlighted the potential of harnessing natural killer (NK) cells in the treatment of neoplastic malignancies. Of these, bispecific antibodies, and NK cell engager (NKCE) protein therapeutics in particular, have been of interest. Here, we used phage display and yeast surface display to engineer RLN131, a unique cross-reactive antibody that binds to human, mouse, and cynomolgus NKp46, an activating receptor found on NK cells.

PET imaging of focused-ultrasound enhanced delivery of AAVs into the murine brain.

Despite recent advances in the use of adeno-associated viruses (AAVs) as potential vehicles for genetic intervention of central and peripheral nervous system-associated disorders, gene therapy for the treatment of neuropathology in adults has not been approved to date. The currently FDA-approved AAV-vector based gene therapies rely on naturally occurring serotypes, such as AAV2 or AAV9, which display limited or no transport across the blood-brain barrier (BBB) if systemically administered. Recently developed engineered AAV variants have shown broad brain transduction and reduced off-target liver toxicity in non-human primates (NHPs).

Development of [F]DASA-10 for enhanced imaging of pyruvate kinase M2.

Purpose: The aim of this study was to develop a positron emission tomography (PET) radiotracer for measuring pyruvate kinase M2 (PKM2) with improved physicochemical and pharmacokinetic properties compared to [F]DASA-23.

Experimental Design: First, we synthesized [F]DASA-10 and tested its uptake and retention compared to [F]DASA-23 in human and mouse glioma cell lines. We then confirmed the specificity of [F]DASA-10 by transiently modulating the expression of PKM2 in DU145 and HeLa cells.

Clinical Radiosynthesis and Translation of [F]OP-801: A Novel Radiotracer for Imaging Reactive Microglia and Macrophages.

Positron emission tomography (PET) is a powerful tool for studying neuroinflammatory diseases; however, current PET biomarkers of neuroinflammation possess significant limitations. We recently reported a promising dendrimer PET tracer ([F]OP-801), which is selectively taken up by reactive microglia and macrophages. Here, we describe further important characterization of [F]OP-801 in addition to optimization and validation of a two-step clinical radiosynthesis.

Multimodal imaging of capsid and cargo reveals differential brain targeting and liver detargeting of systemically-administered AAVs.

The development of gene delivery vehicles with high organ specificity when administered systemically is a critical goal for gene therapy. We combine optical and positron emission tomography (PET) imaging of 1) reporter genes and 2) capsid tags to assess the temporal and spatial distribution and transduction of adeno-associated viruses (AAVs). AAV9 and two engineered AAV vectors (PHP.

Radiosynthesis and initial preclinical evaluation of [C]AZD1283 as a potential P2Y12R PET radiotracer.

Intro: Chronic neuroinflammation and microglial dysfunction are key features of many neurological diseases, including Alzheimer's Disease and multiple sclerosis. While there is unfortunately a dearth of highly selective molecular imaging biomarkers/probes for studying microglia in vivo, P2Y12R has emerged as an attractive candidate PET biomarker being explored for this purpose. Importantly, P2Y12R is selectively expressed on microglia in the CNS and undergoes dynamic changes in expression according to inflammatory context (e.

A Clinical PET Imaging Tracer ([F]DASA-23) to Monitor Pyruvate Kinase M2-Induced Glycolytic Reprogramming in Glioblastoma.

Purpose: Pyruvate kinase M2 (PKM2) catalyzes the final step in glycolysis, a key process of cancer metabolism. PKM2 is preferentially expressed by glioblastoma (GBM) cells with minimal expression in healthy brain. We describe the development, validation, and translation of a novel PET tracer to study PKM2 in GBM.

Minicircles for a two-step blood biomarker and PET imaging early cancer detection strategy.

Early cancer detection can dramatically increase treatment options and survival rates for patients, yet detection of early-stage tumors remains difficult. Here, we demonstrate a two-step strategy to detect and locate cancerous lesions by delivering tumor-activatable minicircle (MC) plasmids encoding a combination of blood-based and imaging reporter genes to tumor cells. We genetically engineered the MCs, under the control of the pan-tumor-specific Survivin promoter, to encode: 1) Gaussia Luciferase (GLuc), a secreted biomarker that can be easily assayed in blood samples; and 2) Herpes Simplex Virus Type 1 Thymidine Kinase mutant (HSV-1 sr39TK), a PET reporter gene that can be used for highly sensitive and quantitative imaging of the tumor location.

Ultra-high-frequency radio-frequency acoustic molecular imaging with saline nanodroplets in living subjects.

Molecular imaging is a crucial technique in clinical diagnostics but it relies on radioactive tracers or strong magnetic fields that are unsuitable for many patients, particularly infants and pregnant women. Ultra-high-frequency radio-frequency acoustic (UHF-RF-acoustic) imaging using non-ionizing RF pulses allows deep-tissue imaging with sub-millimetre spatial resolution. However, lack of biocompatible and targetable contrast agents has prevented the successful in vivo application of UHF-RF-acoustic imaging.

Tumor treating fields (TTFields) impairs aberrant glycolysis in glioblastoma as evaluated by [F]DASA-23, a non-invasive probe of pyruvate kinase M2 (PKM2) expression.

Despite the anti-proliferative and survival benefits from tumor treating fields (TTFields) in human glioblastoma (hGBM), little is known about the effects of this form of alternating electric fields therapy on the aberrant glycolysis of hGBM. [F]FDG is the most common radiotracer in cancer metabolic imaging, but its utility in hGBM is impaired due to high glucose uptake in normal brain tissue. With TTFields, radiochemistry, Western blot, and immunofluorescence microscopy, we identified pyruvate kinase M2 (PKM2) as a biomarker of hGBM response to therapeutic TTFields.

PET Reporter Gene Imaging and Ganciclovir-Mediated Ablation of Chimeric Antigen Receptor T Cells in Solid Tumors.

Imaging strategies to monitor chimeric antigen receptor (CAR) T-cell biodistribution and proliferation harbor the potential to facilitate clinical translation for the treatment of both liquid and solid tumors. In addition, the potential adverse effects of CAR T cells highlight the need for mechanisms to modulate CAR T-cell activity. The herpes simplex virus type 1 thymidine kinase (HSV1-tk) gene has previously been translated as a PET reporter gene for imaging of T-cell trafficking in patients with brain tumor.

Intravital imaging reveals synergistic effect of CAR T-cells and radiation therapy in a preclinical immunocompetent glioblastoma model.

Recent advances in novel immune strategies, particularly chimeric antigen receptor (CAR)-bearing T-cells, have shown limited efficacy against glioblastoma (GBM) in clinical trials. We currently have an incomplete understanding of how these emerging therapies integrate with the current standard of care, specifically radiation therapy (RT). Additionally, there is an insufficient number of preclinical studies monitoring these therapies with high spatiotemporal resolution.

Human biodistribution and radiation dosimetry of [F]DASA-23, a PET probe targeting pyruvate kinase M2.

Purpose: To assess the safety, biodistribution, and radiation dosimetry of the novel positron emission tomography (PET) radiopharmaceutical 1-((2-fluoro-6-[[F]]fluorophenyl)sulfonyl)-4-((4-methoxyphenyl)sulfonyl)piperazine ([F]DASA-23) in healthy volunteers.

Methods: We recruited 5 healthy volunteers who provided a written informed consent. Volunteers were injected with 295.

The Characterization of F-hGTS13 for Molecular Imaging of x Transporter Activity with PET.

The aim of this study was development of an improved PET radiotracer for measuring x activity with increased tumor uptake and reduced uptake in inflammatory cells compared with ()-4-(3-F-fluoropropyl)-l-glutamate (F-FSPG). A racemic glutamate derivative, F-hGTS13, was evaluated in cell culture and animal tumor models. F-hGTS13 was separated into C5 epimers, and the corresponding F-hGTS13-isomer1 and F-hGTS13-isomer2 were evaluated in H460 tumor-bearing rats.

Positron emission tomography reporter gene strategy for use in the central nervous system.

There is a growing need for monitoring or imaging gene therapy in the central nervous system (CNS). This can be achieved with a positron emission tomography (PET) reporter gene strategy. Here we report the development of a PET reporter gene system using the PKM2 gene with its associated radiotracer [F]DASA-23.

Evaluation of Glycolytic Response to Multiple Classes of Anti-glioblastoma Drugs by Noninvasive Measurement of Pyruvate Kinase M2 Using [F]DASA-23.

Purpose: Pyruvate kinase M2 (PKM2) catalyzes the final step in glycolysis, the key process of tumor metabolism. PKM2 is found in high levels in glioblastoma (GBM) cells with marginal expression within healthy brain tissue, rendering it a key biomarker of GBM metabolic re-programming. Our group has reported the development of a novel radiotracer, 1-((2-fluoro- 6-[F]fluorophenyl)sulfonyl)-4-((4-methoxyphenyl)sulfonyl)piperazine ([F]DASA- 23), to non-invasively detect PKM2 levels with positron emission tomography (PET).

Engineered immune cells as highly sensitive cancer diagnostics.

Endogenous biomarkers remain at the forefront of early disease detection efforts, but many lack the sensitivities and specificities necessary to influence disease management. Here, we describe a cell-based in vivo sensor for highly sensitive early cancer detection. We engineer macrophages to produce a synthetic reporter on adopting an M2 tumor-associated metabolic profile by coupling luciferase expression to activation of the arginase-1 promoter.

The Utility of [F]DASA-23 for Molecular Imaging of Prostate Cancer with Positron Emission Tomography.

Purpose: There is a strong, unmet need for superior positron emission tomography (PET) imaging agents that are able to measure biochemical processes specific to prostate cancer. Pyruvate kinase M2 (PKM2) catalyzes the concluding step in glycolysis and is a key regulator of tumor growth and metabolism. Elevation of PKM2 expression was detected in Gleason 8-10 tumors compared to Gleason 6-7 carcinomas, indicating that PKM2 may potentially be a marker of aggressive prostate cancer.

A novel synthesis of 6''-[ F]-fluoromaltotriose as a PET tracer for imaging bacterial infection.

The aim of this study was to develop a positron emission tomography (PET) tracer to visualize and monitor therapeutic response to bacterial infections. In our continued efforts to find maltose based PET tracers that can image bacterial infections, we have designed and prepared 6''-[ F]fluoromaltotriose as a second generation PET imaging tracer targeting the maltodextrin transporter of bacteria. We have developed methods to synthesize 6''-deoxy-6''-[ F]fluoro-α-D-glucopyranosyl-(1-4)-O-α-D-glucopyranosyl-(1-4)-O-D-glucopyranose (6''-[ F]-fluoromaltotriose) as a bacterial infection PET imaging agent.

Development and Preclinical Validation of a Cysteine Knottin Peptide Targeting Integrin αvβ6 for Near-infrared Fluorescent-guided Surgery in Pancreatic Cancer.

Intraoperative near-infrared fluorescence (NIRF) imaging could help stratification for the proper primary treatment for patients with pancreatic ductal adenocarcinoma (PDAC), and achieve complete resection, as it allows visualization of cancer in real time. Integrin αvβ6, a target specific for PDAC, is present in >90% of patients, and is able to differentiate between pancreatitis and PDAC. A clinically translatable αvβ6-targeting NIRF agent was developed, based on a previously developed cysteine knottin peptide for PET imaging, R01-MG, and validated in preclinical mouse models.

Development of [F]DASA-23 for Imaging Tumor Glycolysis Through Noninvasive Measurement of Pyruvate Kinase M2.

Purpose: A hallmark of cancer is metabolic reprogramming, which is exploited by cancer cells to ensure rapid growth and survival. Pyruvate kinase M2 (PKM2) catalyzes the final step in glycolysis, a key step in tumor metabolism and growth. Recently, we reported the radiosynthesis of the first positron emission tomography tracer for visualizing PKM2 in vivo-i.

Effects of common anesthetic agents on [F]flumazenil binding to the GABA receptor.

Background: The availability of GABA receptor binding sites in the brain can be assessed by positron emission tomography (PET) using the radioligand, [F]flumazenil. However, the brain uptake and binding of this PET radioligand are influenced by anesthetic drugs, which are typically needed in preclinical imaging studies and clinical imaging studies involving patient populations that do not tolerate relatively longer scan times. The objective of this study was to examine the effects of anesthesia on the binding of [F]flumazenil to GABA receptors in mice.

The Recent Development of α7 Nicotinic Acetylcholine Receptor (nAChR) Ligands as Therapeutic Candidates for the Treatment of Central Nervous System (CNS) Diseases.

Homomeric α7 nicotinic acetylcholine receptors (nAChRs) are implicated in the regulation of cognitive processes such as memory and attention and have potential as therapeutic targets for the treatment of the cognitive deficits associated with schizophrenia. Though numerous α7 nAChR agonists have been developed, and several have progressed to clinical trials, these are derived from few common chemotypes. Consequently, many of these α7 nAChR clinical candidates share unfavorable side-effect profile.

The therapeutic potential of α7 nicotinic acetylcholine receptor (α7 nAChR) agonists for the treatment of the cognitive deficits associated with schizophrenia.

Homomeric α7 nicotinic acetylcholine receptors (α7 nAChRs) have implications in the regulation of cognitive processes such as memory and attention, and have shown promise as a therapeutic target for the treatment of the cognitive deficits associated with schizophrenia. Multiple α7 nAChR agonists have entered human trials; however, unfavorable side effects and pharmacokinetic issues have hindered the development of a clinical α7 nAChR agonist. Currently, EVP-6124 is in phase III clinical trials, and several other α7 nAChR agonists (GTS-21 and AQW051) are in earlier stages of development.