Controversies over anti-amyloid immunotherapies underscore the need to elucidate their mechanisms of action. Here we demonstrate that Lecanemab, a leading anti-β-amyloid (Aβ) antibody, mediates amyloid clearance by activating microglial effector functions. Using a human microglia xenograft mouse model, we show that Lecanemab significantly reduces Aβ pathology and associated neuritic damage, while neither fragment crystallizable (Fc)-silenced Lecanemab nor microglia deficiency elicits this effect despite intact plaque binding. Single-cell RNA sequencing and spatial transcriptomic analyses reveal that Lecanemab induces a focused transcriptional program that enhances phagocytosis, lysosomal degradation, metabolic reprogramming, interferon γ genes and antigen presentation. Finally, we identify SPP1 /osteopontin as a major factor induced by Lecanemab treatment and demonstrate its role in promoting Aβ clearance. These findings highlight that effective amyloid removal depends on the engagement of microglia through the Fc fragment, providing critical insights for optimizing anti-amyloid therapies in Alzheimer’s disease.

Early assessment of metabolism pathways of new chemical entities (NCEs) guides the understanding of drug-drug interactions (DDIs). Selective enzyme inhibitors are indispensable in cytochrome P450 (CYP) reaction phenotyping. The most commonly applied CYP2C19 inhibitor, omeprazole, lacks selectivity. Two promising alternatives, (+)-N-3-benzylnirvanol and (-)-N-3-benzylphenobarbital, are already used as CYP2C19 inhibitors in some in vitro studies with suspended human hepatocytes. However, a full validation proving their suitability in terms of CYP and non-CYP selectivity has not been presented in literature. The present study provides a thorough comparison between omeprazole, (+)-N-3-benzylnirvanol, and (-)-N-3-benzylphenobarbital in terms of potency and selectivity, and shows the superiority of (-)-N-3-benzylphenobarbital as a CYP2C19 inhibitor in suspended human hepatocytes. Furthermore, we evaluated the application of (-)-N-3-benzylphenobarbital to predict the in vivo contribution of CYP2C19 to drug metabolism (fm_CYP2C19). A set of ten clinically used CYP2C19 substrates with reported in vivo fm_CYP2C19 data was evaluated. Fm_CYP2C19, which was predicted using datafrom suspended human hepatocyte incubations, underestimated the in vivo fm_CYP2C19. The use of a different hepatocyte batch with a different CYP3A4/CYP2C19 activity ratio, showed the impact of intrinsic CYP activities on the determination of fm_CYP2C19. Overall, this study confirms the selective CYP2C19 inhibition by (-)-N-3-benzylphenobarbital over other CYP isoforms (CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2D6, and CYP3A4) and clinically relevant non-CYP enzymes (AO, FMO3, NAT2, UGT1A1, UGT1A4, UGT2B7, UGT2B15) in suspended human hepatocytes. (-)-N-3-benzylphenobarbital is therefore the preferred CYP2C19 inhibitor to assess fm_CYP2C19 in suspended human hepatocytes in comparison to omeprazole and (+)-N-3-benzylnirvanol. Significance Statement (-)-N-3-benzylphenobarbital is a more potent and selective inhibitor of CYP2C19 in suspended human hepatocytes than omeprazole. (-)-N-3-benzylphenobarbital can be used to predict the fraction metabolized by CYP2C19 in suspended human hepatocytes.

DNA-based antibody therapy seeks to administer the encoding nucleotide sequence rather than the antibody protein. To further improve the in vivo monoclonal antibody (mAb) expression, a better understanding of what happens after the administration of the encoding plasmid DNA (pDNA) is required. This study reports the quantitative evaluation and localization of the administered pDNA over time and its association with corresponding mRNA levels and systemic protein concentrations. pDNA encoding the murine anti-HER2 4D5 mAb was administered to BALB/c mice via intramuscular injection followed by electroporation. Muscle biopsies and blood samples were taken at different time points (up to 3 months). In muscle, pDNA levels decreased 90% between 24 h and one week post treatment (p < 0.0001). In contrast, mRNA levels remained stable over time. The 4D5 antibody plasma concentrations reached peak levels at week two followed by a slow decrease (50% after 12 weeks, p < 0.0001). Evaluation of pDNA localization revealed that extranuclear pDNA was cleared fast, whereas the nuclear fraction remained relatively stable. This is in line with the observed mRNA and protein levels over time and indicates that only a minor fraction of the administered pDNA is ultimately responsible for the observed systemic mAb levels. In conclusion, this study demonstrates that durable expression is dependent on the nuclear uptake of the pDNA. Therefore, efforts to increase the protein levels upon pDNA-based gene therapy should focus on strategies to increase both cellular entry and migration of the pDNA into the nucleus. The currently applied methodology can be used to guide the design and evaluation of novel plasmid-based vectors or alternative delivery methods in order to achieve a robust and prolonged protein expression.

Two‐photon polymerization (TPP) is an additive manufacturing technique with micron‐scale resolution that is rapidly gaining ground for a range of biomedical applications. TPP is particularly attractive for the creation of microscopic three‐dimensional structures in biocompatible and noncytotoxic resins. Here, TPP is used to develop microfluidic interfaces which provide chronic fluidic access to the brain of preclinical research models. These microcatheters can be used for either convection‐enhanced delivery (CED) or for the repeated collection of liquid biopsies. In a brain phantom, infusions with the micronozzle result in more localized distribution clouds and lower backflow compared to a control catheter. In mice, the delivery interface enables faster, more precise, and physiologically less disruptive fluid injections. A second microcatheter design enables repeated, longitudinal sampling of cerebrospinal fluid (CSF) over time periods as long as 250 days. Moreover, further in vivo studies demonstrate that the blood‐CSF barrier is intact after chronic implantation of the sampling interface and that samples are suitable for downstream molecular analysis for the identification of nucleic acid‐ or peptide‐based biomarkers. Ultimately, the versatility of this fabrication technique implies a great translational potential for simultaneous drug delivery and biomarker tracking in a range of human neurological diseases.

Background: Therapeutic antibodies for the treatment of neurological disease show great potential, but their applications are rather limited due to limited brain exposure. The most well-studied approach to enhance brain influx of protein therapeutics, is receptor-mediated transcytosis (RMT) by targeting nutrient receptors to shuttle protein therapeutics over the blood-brain barrier (BBB) along with their endogenous cargos. While higher brain exposure is achieved with RMT, the timeframe is short due to rather fast brain clearance. Therefore, we aim to increase the brain half-life of antibodies by binding to myelin oligodendrocyte glycoprotein (MOG), a CNS specific protein. Methods: Alpaca immunization with mouse/human MOG, and subsequent phage selections and screenings for MOG binding VHHs were performed to find mouse/human cross-reactive VHHs. Their ability to increase the brain half-life of antibodies was evaluated by coupling two different MOG VHHs (low/high affinity) in a mono- and bivalent format to an anti-β-secretase 1 or anti-SarsCov2 antibody fused to an anti-transferrin receptor (TfR) VHH for active transport over the BBB. Brain pharmacokinetics and pharmacodynamics, CNS and peripheral biodistribution, and brain toxicity were evaluated after intravenous administration to balb/c mice. Results: Additional binding to MOG increases the C _max and brain half-life of antibodies that are actively shuttled over the BBB. biMOG _Low :monoTfR:SarsCov antibodies could be detected in brain 49 days after a single intravenous injection, which is a major improvement compared to monoTfR:SarsCov antibodies which cannot be detected in brain anymore one week post treatment. Additional MOG binding of antibodies does not affect peripheral biodistribution but alters brain distribution to white matter localization and less neuronal internalization. Conclusions: We have discovered mouse/human/cyno cross-reactive anti-MOG VHHs which have the ability to drastically increase brain exposure of antibodies. Combining MOG and TfR binding leads to distinct PK, biodistribution, and brain exposure, differentiating it from the highly investigated TfR- shuttling. It is the first time such long brain antibody exposure is demonstrated after one single dose. This new approach of adding a binding moiety for brain specific targets to RMT shuttling antibodies is a huge advancement for the field and paves the way for further research into brain half-life extension.

A bstract: Here, we used micron-scale 3D printing to develop microfluidic interfaces which provide chronic fluidic access to the brain of preclinical research models. In mice, we show the delivery interface enables faster, more precise and physiologically less disruptive fluid injection. Moreover, we demonstrate the blood brain barrier (BBB) is intact after chronic implantation of the sampling interface and establish frequent, longitudinal sampling of CSF and biomarkers from the ventricle over long time periods of up to 200 days.