PET imaging

Utilizing integrin-targeted PET imaging and therapeutics to predict and treat radiation-induced pulmonary fibrosis

Project Summary/Abstract. Lung cancer is the leading cause of cancer death in the US, with over 125,000 deaths annually. Radiation therapy (RT) is a critical component of curative lung cancer treatment for many patients. However, radiationinduced pulmonary fibrosis (RIPF) is a common side effect that carries a poor prognosis with limited treatment options. Up to 40% of patients with lung cancer who receive RT may experience RIPF. RIPF is a late effect of RT, typically occurring 3 or more months after treatment. The symptoms of RIPF can include shortness of breath, pleural effusions, decreased lung function, and respiratory failure. Cell surface integrin heterodimers play a key role in the pathogenesis of RIPF. In particular, the integrin αvβ6, which is expressed at a low level in the alveolar epithelium at baseline, is significantly upregulated upon RT damage. The key role of integrin αvβ6 in RIPF is illustrated by studies in which mice lacking integrin αvβ6, or treated with an αvβ6-blocking antibody, do not develop RIPF. Here, we propose to translate this mechanistic understanding of RIPF into novel approaches for monitoring and treating RIPF. We hypothesize that non-invasive αvβ6 PET imaging will be safe and can specifically bind to αvβ6 in patients with RIPF. Additionally, we hypothesize that a novel small-molecule integrin antagonist, IDL2965, can mitigate and treat RIPF in mice. In this project, we are utilizing mice to model RIPF, as mice develop RIPF that mimics human disease. In addition, cellular and in vitro models do not approximate the complex biology leading to the development of RIPF. Our data using [64Cu]Cu-DOTA-αvβ6-BP to detect early RIPF in mice are compelling in both single-fraction high-dose RT and lower dose-larger volume RT models (Lo et. al, IJROBP 2025). However, to progress to clinical trials in patients with cancer, we will obtain data to submit an Investigational New Drug (IND) application to the FDA. Importantly, we propose translating [64Cu]Cu-DOTA-αvβ6-BP PET imaging into patients with lung cancer, allowing us to better identify RIPF and develop a tool to determine the efficacy of IDL-2965 in future clinical studies. The specific aims of the proposal are: (1) Characterize the utility of [64Cu]Cu-DOTA-αvβ6-BP in mice with conventionally fractionated RT and identify circulating biomarkers of RIPF, and determine the in vivo toxicology of [64Cu]Cu-DOTA-αvβ6-BP to prepare and submit an exploratory Investigational New Drug (eIND) application to the FDA, (2) Conduct a first-in-human clinical trial of [64Cu]Cu-DOTA-αvβ6-BP to determine its safety and human dosimetry in patients with evidence of RIPF from computed tomography or in healthy controls, and (3) Determine the effect of integrin antagonism using IDL-2965 on mitigating RIPF in preclinical mouse models. The goals of this proposal are two-fold: (1) demonstrate safety and target specificity for [64Cu]Cu-DOTA-αvβ6-BP so that it can be used in future studies to identify RIPF and evaluate the efficacy of anti-fibrotic therapies, and 2) determine the ability of IDL-2965 to prevent RIPF in preclinical mouse models.

Circadian regulation of reperfusion efficacy in acute ischemic stroke

Reperfusion with thrombectomy has changed the clinical landscape for ischemic stroke. Recently, some studies suggest that patients with “large cores” may still benefit from reperfusion. Why? If these “cores” represent dead brain, why should reperfusion help? One logical explanation is that currently used neuroimaging “cores”, do not always identify uniformly dead tissue. Our pilot data suggest that these “cores” include tissue with a wide range of injury, indicated as changes in relative CT Hounsfield Units (rHU). Importantly, circadian mechanisms may be involved. Ischemic tissue with less severe changes in rHU tend to occur in the morning (active phase) when responses to reperfusion are better. In mouse models of stroke, ischemic injury is also less severe when strokes occur during the nighttime (active phase for nocturnal animals). In contrast, more severe ischemic injury during the daytime (inactive phase for mice) is accompanied by dampened vasodilation and CBF response along with increased immunothrombosis and neutrophil extracellular traps (NETosis). Is it possible that understanding these circadian mechanisms may help identify patients who respond best to reperfusion? And is it possible that targeting these circadian mechanisms can help convert non- responders into responders? In this multi-PI project, we use a translational approach (clinical neuroimaging and biomarkers in stroke patients, mouse models of stroke, CT-PET imaging of tissue viability, molecular pharmacology) with three integrated aims that can be pursued in parallel. Aim 1 will use neuroimaging in stroke patients to show that less severe rHU values in reperfusion-responsive “cores” tend to occur in the morning, whereas more severe rHU values in reperfusion-non-responsive “cores” occur later. Aim 2 will use clinical biomarkers to show that more severe rHU “cores” that are not reperfusion-responsive correlate with circadian effects on vasodilation and immunothrombosis. Aim 3 will use mouse stroke models to test whether targeting these circadian mechanisms of vasodilation and immunothrombosis can convert reperfusion-non-responders into reperfusion-responders. Patients cannot choose when they have a stroke. So why should we pay attention to circadian mechanisms? There may be 2 reasons that are addressed by the present project. First, thrombectomy is resource-intensive, and in spite of the very low number-needed-to-treat, only 20% of “large core” patients do well after reperfusion. Our studies may help identify who (when) these responders are. Second, the pathophysiologic mechanisms of cerebral ischemia differ depending on time-of-day. Therefore, understanding and then targeting these circadian mechanisms may allow us to convert reperfusion non-responders into responders.

PET imaging in brain diseases

Talk 1. PET based biomarkers of treatment efficacy in temporal lobe epilepsy A critical aspect of drug development involves identifying robust biomarkers of treatment response for use as surrogate endpoints in clinical trials. However, these biomarkers also have the capacity to inform mechanisms of disease pathogenesis and therapeutic efficacy. In this webinar, Dr Bianca Jupp will report on a series of studies using the GABAA PET ligand, [18F]-Flumazenil, to establish biomarkers of treatment response to a novel therapeutic for temporal lobe epilepsy, identifying affinity at this receptor as a key predictor of treatment outcome. Dr Bianca Jupp is a Research Fellow in the Department of Neuroscience, Monash University and Lead PET/CT Scientist at the Alfred Research Alliance–Monash Biomedical Imaging facility. Her research focuses on neuroimaging and its capacity to inform the neurobiology underlying neurological and neuropsychiatric disorders. Talk 2. The development of a PET radiotracer for reparative microglia Imaging of neuroinflammation is currently hindered by the technical limitations associated with TSPO imaging. In this webinar, Dr Lucy Vivash will discuss the development of PET radiotracers that specifically image reparative microglia through targeting the receptor kinase MerTK. This includes medicinal chemistry design and testing, radiochemistry, and in vitro and in vivo testing of lead tracers. Dr Lucy Vivash is a Research Fellow in the Department of Neuroscience, Monash University. Her research focuses on the preclinical development and clinical translation of novel PET radiotracers for the imaging of neurodegenerative diseases.

Growing a world-class precision medicine industry

Monash Biomedical Imaging is part of the new $71.2 million Australian Precision Medicine Enterprise (APME) facility, which will deliver large-scale development and manufacturing of precision medicines and theranostic radiopharmaceuticals for industry and research. A key feature of the APME project is a high-energy cyclotron with multiple production clean rooms, which will be located on the Monash Biomedical Imaging (MBI) site in Clayton. This strategic co-location will facilitate radiochemistry, PET and SPECT research and clinical use of theranostic (therapeutic and diagnostic) radioisotopes produced on-site. In this webinar, MBI’s Professor Gary Egan and Dr Maggie Aulsebrook will explain how the APME will secure Australia’s supply of critical radiopharmaceuticals, build a globally competitive Australian manufacturing hub, and train scientists and engineers for the Australian workforce. They will cover the APME’s state-of-the-art 30 MeV and 18-24 MeV cyclotrons and radiochemistry facilities, as well as the services that will be accessible to students, scientists, clinical researchers, and pharmaceutical companies in Australia and around the world. The APME is a collaboration between Monash University, Global Medical Solutions Australia, and Telix Pharmaceuticals. Professor Gary Egan is Director of Monash Biomedical Imaging, Director of the ARC Centre of Excellence for Integrative Brain Function and a Distinguished Professor at the Turner Institute for Brain and Mental Health, Monash University. He is also lead investigator of the Victorian Biomedical Imaging Capability, and Deputy Director of the Australian National Imaging Facility. Dr Maggie Aulsebrook obtained her PhD in Chemistry at Monash University and specialises in the development and clinical translation of radiopharmaceuticals. She has led the development of several investigational radiopharmaceuticals for first-in-human application. Maggie leads the Radiochemistry Platform at Monash Biomedical Imaging.

NMC4 Keynote: A network perspective on cognitive effort

Cognitive effort has long been an important explanatory factor in the study of human behavior in health and disease. Yet, the biophysical nature of cognitive effort remains far from understood. In this talk, I will offer a network perspective on cognitive effort. I will begin by canvassing a recent perspective that casts cognitive effort in the framework of network control theory, developed and frequently used in systems engineering. The theory describes how much energy is required to move the brain from one activity state to another, when activity is constrained to pass along physical pathways in a connectome. I will then turn to empirical studies that link this theoretical notion of energy with cognitive effort in a behaviorally demanding task, and with a metabolic notion of energy as accessible to FDG-PET imaging. Finally, I will ask how this structurally-constrained activity flow can provide us with insights about the brain’s non-equilibrium nature. Using a general tool for quantifying entropy production in macroscopic systems, I will provide evidence to suggest that states of marked cognitive effort are also states of greater entropy production. Collectively, the work I discuss offers a complementary view of cognitive effort as a dynamical process occurring atop a complex network.

Blood phosphorylated tau as biomarkers for Alzheimer’s disease

Alzheimer's disease (AD) is the most common cause of dementia, and its health and socioeconomic burdens are of major concern. Presently, a definite diagnosis of AD is established by examining brain tissue after death. These examinations focus on two major pathological hallmarks of AD in the brain: (i) amyloid plaques consisting of aggregated amyloid beta (Aβ) peptides and (ii) neurofibrillary tangles made of abnormally phosphorylated tau protein. In living individuals, AD diagnosis relies on two main approaches: (i) brain imaging of tau tangles and Aβ plaques using a technique called positron emission tomography (PET) and (ii) measuring biochemical changes in tau (including phosphorylated tau at threonine-181 [p-tau181]) and the Aβ42 peptide metabolized into CSF. Unlike Aβ42, CSF p-tau181 is highly specific for AD but its usability is restricted by the need of a lumbar puncture. Moreover, PET imaging is expensive and only available in specialised medical centres. Due to these shortcomings, a simple blood test that can detect disease-related changes in the brain is a high priority for AD research, clinical care and therapy testing. In this webinar, I will discuss the discovery of p-tau biomarkers in blood and the biochemistry of how these markers differ from those found in CSF. Furthermore, I will critically review the performance of blood p-tau biomarkers across the AD pathological process and how they associate with and predict Aβ and tau pathophysiological and neuropathological changes. Furthermore, I will evaluate the potential advantages, challenges and context of use of blood p-tau in clinical practice, therapeutic trials and population screening.

Development and Application of PET Imaging for Dementia Research

Molecular imaging using Positron Emission Tomography (PET) has become a major biomedical imaging technology. Its application towards characterisation of biochemical processes in disease could enable early detection and diagnosis, development of novel therapies and treatment evaluation. The technology is underpinned by the use of imaging probes radiolabelled with short-lived radioisotopes which can be specific and selective for biological targets in vivo e.g. markers for receptors, protein deposits, enzymes and metabolism. My talk will focus on the increasing development and application of PET imaging to clinical research in neurodegenerative diseases, for which it can be applied to delineate and understand the various pathological components of these disorders.

Evaluation of repetitive mild traumatic brain injury by fluorescence and FDG PET imaging