Investigation of the Impact of the H310A FcRn Region Mutation on Zr-Immuno-PET Brain Imaging with a BBB-Shuttle Anti‑Amyloid Beta Antibody.

Purpose: In the emerging field of antibody treatments for neurodegenerative diseases, reliable tools are needed to evaluate new therapeutics, diagnose and select patients, monitor disease progression, and assess therapy response. Immuno-PET combines the high affinity and exceptional specificity of monoclonal antibodies with the non-invasive imaging technique positron emission tomography (PET). Its application in neurodegenerative disease brain imaging has been limited due to the marginal uptake across the blood-brain barrier (BBB).

Navigating the landscape of PD-1/PD-L1 imaging tracers: from challenges to opportunities.

Immunotherapy targeted to immune checkpoint inhibitors, such as the program cell death receptor (PD-1) and its ligand (PD-L1), has revolutionized cancer treatment. However, it is now well-known that PD-1/PD-L1 immunotherapy response is inconsistent among patients. The current challenge is to customize treatment regimens per patient, which could be possible if the PD-1/PD-L1 expression and dynamic landscape are known.

Synthesis and preclinical evaluation of [C]EAI045 as a PET tracer for imaging tumors expressing mutated epidermal growth factor receptor.

Background: Mutations in the epidermal growth factor receptor (EGFR) kinase domain are common in non-small cell lung cancer. Conventional tyrosine kinase inhibitors target the mutation site in the ATP binding pocket, thereby inhibiting the receptor's function. However, subsequent treatment resistance mutations in the ATP binding site are common.

Development of F-Labeled PET Tracer Candidates for Imaging of the Abelson Non-receptor Tyrosine Kinase in Parkinson's Disease.

Activated Abelson non-receptor tyrosine kinase (c-Abl) plays a harmful role in neurodegenerative conditions such as Parkinson's disease (PD). Inhibition of c-Abl is reported to have a neuroprotective effect and be a promising therapeutic strategy for PD. We have previously identified a series of benzo[]thiazole derivatives as selective c-Abl inhibitors from which one compound showed high therapeutic potential.

Synthesis and Preclinical Evaluation of [-C]brigatinib as a PET Tracer Targeting Both Mutated Epidermal Growth Factor Receptor and Anaplastic Lymphoma Kinase.

Brigatinib, a tyrosine kinase inhibitor (TKI) with specificity for gene rearranged anaplastic lymphoma kinase (ALK), such as the EML4-ALK, has shown a potential to inhibit mutated epidermal growth factor receptor (EGFR). In this study, -desmethyl brigatinib was successfully synthesized as a precursor in five steps. Radiolabeling with [C]methyl iodide produced [-C]brigatinib in a 10 ± 2% radiochemical yield, 91 ± 17 GBq/μmol molar activity, and ≥95% radiochemical purity in 49 ± 4 min.

Synthesis and preclinical evaluation of two osimertinib isotopologues labeled with carbon-11 as PET tracers targeting the tyrosine kinase domain of the epidermal growth factor receptor.

Introduction: Osimertinib is a third-generation tyrosine kinase inhibitor (TKI) that is able to inhibit the EGFR treatment resistance mutation T790M and primary EGFR mutations Del19 and L858R. The aim of the study was to evaluate the potential of carbon-11 labeled osimertinib to be used as a tracer for the PET imaging of tumors bearing the T790M mutation.

Methods: Osimertinib was labeled with carbon-11 at two positions, and the effect of the labeling position on the metabolism and biodistribution was studied in female nu/nu mice.

Imaging the TGFβ type I receptor in pulmonary arterial hypertension.

Transforming growth factor β (TGFβ) activity is perturbed in remodelled pulmonary vasculature of patients with pulmonary arterial hypertension (PAH), cancer, vascular diseases and developmental disorders. Inhibition of TGFβ, which signals via activin receptor-like kinase 5 (ALK5), prevents progression and development of experimental PAH. The purpose of this study was to assess two ALK5 targeting positron emission tomography (PET) tracers ([C]LR111 and [F]EW-7197) for imaging ALK5 in monocrotaline (MCT)- and Sugen/hypoxia (SuHx)-induced PAH.

Advancing Zr-immuno-PET in neuroscience with a bispecific anti-amyloid-beta monoclonal antibody - The choice of chelator is essential.

The accelerated approval of the monoclonal antibody (mAb) aducanumab as a treatment option for Alzheimer's Disease and the continued discussions about its efficacy have shown that a better understanding of immunotherapy for the treatment of neurodegenerative diseases is needed. Zr-immuno-PET could be a suitable tool to open new avenues for the diagnosis of CNS disorders, monitoring disease progression, and assessment of novel therapeutics. Herein, three different Zr-labeling strategies and direct radioiodination with I of a bispecific anti-amyloid-beta aducanumab derivate, consisting of aducanumab with a C-terminal fused anti-transferrin receptor binding single chain Fab fragment derived from 8D3 (Adu-8D3), were compared and with regard to brain uptake and target engagement in an APP/PS1 Alzheimer's disease mouse model and wild type animals.

Synthesis and preclinical evaluation of [C]LR111 and [F]EW-7197 as PET tracers of the activin-receptor like kinase-5.

The transforming growth factor β (TGFβ) pathway plays a complex role in cancer biology, being involved in both tumour suppression as well as promotion. Overactive TGFβ signalling has been linked to multiple diseases, including cancer, pulmonary arterial hypertension, and fibrosis. One of the key meditators within this pathway is the TGFβ type I receptor, also termed activin receptor-like kinase 5 (ALK5).

Pretargeted PET Imaging with a TCO-Conjugated Anti-CD44v6 Chimeric mAb U36 and [Zr]Zr-DFO-PEG-Tz.

The recent advances in the production of engineered antibodies have facilitated the development and application of tailored, target-specific antibodies. Positron emission tomography (PET) of these antibody-based drug candidates can help to better understand their behavior. In this study, we report an proof-of-concept pretargeted immuno-PET study where we compare a pretargeting vs targeted approach using a new Zr-labeled tetrazine as a bio-orthogonal ligand in an inverse electron demand Diels-Alder (IEDDA) click reaction.

Immuno-PET Imaging of Atherosclerotic Plaques with [Zr]Zr-Anti-CD40 mAb-Proof of Concept.

Non-invasive imaging of atherosclerosis can help in the identification of vulnerable plaque lesions. CD40 is a co-stimulatory molecule present on various immune and non-immune cells in the plaques and is linked to inflammation and plaque instability. We hypothesize that a Zr-labeled anti-CD40 monoclonal antibody (mAb) tracer has the potential to bind to cells present in atherosclerotic lesions and that CD40 Positron Emission Tomography (PET) can contribute to the detection of vulnerable atherosclerotic plaque lesions.

α-Synuclein Radiotracer Development and In Vivo Imaging: Recent Advancements and New Perspectives.

α-Synucleinopathies including idiopathic Parkinson's disease, dementia with Lewy bodies and multiple systems atrophy share overlapping symptoms and pathological hallmarks. Selective neurodegeneration and Lewy pathology are the main hallmarks of α-synucleinopathies. Currently, there is no imaging biomarker suitable for a definitive early diagnosis of α-synucleinopathies.

Folate Receptor Beta for Macrophage Imaging in Rheumatoid Arthritis.

Non-invasive imaging modalities constitute an increasingly important tool in diagnostic and therapy response monitoring of patients with autoimmune diseases, including rheumatoid arthritis (RA). In particular, macrophage imaging with positron emission tomography (PET) using novel radiotracers based on differential expression of plasma membrane proteins and functioning of cellular processes may be suited for this. Over the past decade, selective expression of folate receptor β (FRβ), a glycosylphosphatidylinositol-anchored plasma membrane protein, on myeloid cells has emerged as an attractive target for macrophage imaging by exploiting the high binding affinity of folate-based PET tracers.

Novel Thienopyrimidine-Based PET Tracers for P2Y Receptor Imaging in the Brain.

The P2Y receptor (P2YR) is uniquely expressed on microglia in the brain, and its expression level directly depends on the microglial activation state. Therefore, P2YR provides a promising imaging marker for distinguishing the pro- and anti-inflammatory microglial phenotypes, both of which play crucial roles in neuroinflammatory diseases. In this study, three P2YR antagonists were selected from the literature, radiolabeled with carbon-11 or fluorine-18, and evaluated in healthy Wistar rats.

Synthesis and evaluation of [F]cinacalcet for the imaging of parathyroid hyperplasia.

Introduction: Parathyroid hyperplasia is a disease characterized by overactive parathyroid glands secreting increased levels of parathyroid hormone. Surgical removal of the parathyroid glands is the standard treatment but requires precise pre-operative localization of the glands. However, currently available imaging modalities show limited sensitivity.

Towards PET imaging of the dynamic phenotypes of microglia.

There is increasing evidence showing the heterogeneity of microglia activation in neuroinflammatory and neurodegenerative diseases. It has been hypothesized that pro-inflammatory microglia are detrimental and contribute to disease progression, while anti-inflammatory microglia play a role in damage repair and remission. The development of therapeutics targeting the deleterious glial activity and modulating it into a regenerative phenotype relies heavily upon a clearer understanding of the microglia dynamics during disease progression and the ability to monitor therapeutic outcome in vivo.

Retention of Cu-FLFLF, a Formyl Peptide Receptor 1-Specific PET Probe, Correlates with Macrophage and Neutrophil Abundance in Lung Granulomas from Cynomolgus Macaques.

Neutrophilic inflammation correlates with severe tuberculosis (TB), a disease caused by (). Granulomas are lesions that form in TB, and a PET probe for following neutrophil recruitment to granulomas could predict disease progression. We tested the formyl peptide receptor 1 (FPR1)-targeting peptide FLFLF in -infected macaques.

Performance of nanoScan PET/CT and PET/MR for quantitative imaging of F and Zr as compared with ex vivo biodistribution in tumor-bearing mice.

Introduction: The assessment of ex vivo biodistribution is the preferred method for quantification of radiotracers biodistribution in preclinical models, but is not in line with current ethics on animal research. PET imaging allows for noninvasive longitudinal evaluation of tracer distribution in the same animals, but systemic comparison with ex vivo biodistribution is lacking. Our aim was to evaluate the potential of preclinical PET imaging for accurate tracer quantification, especially in tumor models.

The Role of Zr-Immuno-PET in Navigating and Derisking the Development of Biopharmaceuticals.

The identification of molecular drivers of disease and the compelling rise of biotherapeutics have impacted clinical care but have also come with challenges. Such therapeutics include peptides, monoclonal antibodies, antibody fragments and nontraditional binding scaffolds, activatable antibodies, bispecific antibodies, immunocytokines, antibody-drug conjugates, enzymes, polynucleotides, and therapeutic cells, as well as alternative drug carriers such as nanoparticles. Drug development is expensive, attrition rates are high, and efficacy rates are lower than desired.

PET imaging of P2XR in the experimental autoimmune encephalomyelitis model of multiple sclerosis using [C]SMW139.

Background: Non-invasive imaging of the activation status of microglia and the ability to identify a pro- or anti-inflammatory environment can provide valuable insights not only into pathogenesis of neuro-inflammatory and neurodegenerative diseases but also the monitoring of the efficacy of immunomodulatory therapies. P2XR is highly expressed on pro-inflammatory microglia and [C]SMW139, a specific P2XR tracer for positron emission tomography imaging, showed good pharmacokinetics, stability, and brain permeability in vivo. Our objective was to evaluate the potential of [C]SMW139 for PET imaging of neuroinflammation in vivo in the experimental autoimmune encephalomyelitis (EAE) model.

Head-to-head comparison of DFO* and DFO chelators: selection of the best candidate for clinical Zr-immuno-PET.

Purpose: Almost all radiolabellings of antibodies with Zr currently employ the hexadentate chelator desferrioxamine (DFO). However, DFO can lead to unwanted uptake of Zr in bones due to instability of the resulting metal complex. DFO*-NCS and the squaramide ester of DFO, DFOSq, are novel analogues that gave more stable Zr complexes than DFO in pilot experiments.

Altered secretory and neuroprotective function of the choroid plexus in progressive multiple sclerosis.

The choroid plexus (CP) is a key regulator of the central nervous system (CNS) homeostasis through its secretory, immunological and barrier properties. Accumulating evidence suggests that the CP plays a pivotal role in the pathogenesis of multiple sclerosis (MS), but the underlying mechanisms remain largely elusive. To get a comprehensive view on the role of the CP in MS, we studied transcriptomic alterations of the human CP in progressive MS and non-neurological disease controls using RNA sequencing.

The P2X receptor tracer [C]SMW139 as an in vivo marker of neuroinflammation in multiple sclerosis: a first-in man study.

Purpose: The novel PET tracer [C]SMW139 binds with high affinity to the P2X receptor, which is expressed on pro-inflammatory microglia. The purposes of this first in-man study were to characterise pharmacokinetics of [C]SMW139 in patients with active relapsing remitting multiple sclerosis (RRMS) and healthy controls (HC) and to evaluate its potential to identify in vivo neuroinflammation in RRMS.

Methods: Five RRMS patients and 5 age-matched HC underwent 90-min dynamic [C]SMW139 PET scans, with online continuous and manual arterial sampling to generate a metabolite-corrected arterial plasma input function.