Molecular Therapy Nucleic Acids

Antisense oligonucleotides (ASOs) represent a promising therapeutic modality for RNA-based disease mechanisms, but identifying high-efficacy candidates from large sequence spaces remains a major bottleneck in drug development. Here, we present ASOFormer, a novel Transformer-based neural network that predicts the inhibition efficiency of RNase H-mediated ASOs from sequence, predicted secondary structure, and chemical modification features. ASOFormer was trained on a knockdown efficacy dataset spanning over 170,000 ASO-target pairs compiled largely from published patents. Ablation analysis confirmed that the addition of chemical modification features to the primary sequence drove the largest performance gains, with predicted secondary structure providing complementary benefit when combined with modification information. Further analysis highlighted the importance of the wings of gapmer ASOs and other features. As independent validation, ASOFormer was applied to ASOs targeting seven genes that were not in the training dataset gene list. For four out of the seven genes, the ground truth ASO inhibition efficiency was obtained from a public dataset, whereas the others were measured in-house via qPCR. Compared to two published state-of-the-art methods, ASOFormer achieved the best overall accuracy and prioritized the strongest inhibitors. Crucially, only ASOFormer consistently exceeded random expectation for top-candidate recovery across all seven test genes.

We report a neonate with IOPD who had high pre-existing anti-AAV9 antibody titers, which precluded eligibility for AAV9-mediated gene therapy (GC301). Preconditioning with a single dose of the IgG-degrading enzyme GC801 (0.2 mg/kg) safely reduced serum IgG from 6.25 g/L to a nadir of 0.72 g/L within 5 days. This pharmacological window facilitated successful GC301 vector transduction, driving a robust increase in GAA activity to 19.38 mmol/L/16h by day 84. Crucially, no adverse events beyond the underlying IOPD were observed. Our findings support the potential utility of GC801 as an agent to overcome pre-existing humoral barriers in neonatal gene therapy candidates.

Reactivation of telomerase confers immortality to approximately 90% of human tumors by enabling continuous elongation of the DNA at chromosome ends, or telomeres. The telomerase catalytic subunit TERT adds TTAGGG repeats using a portion of the telomerase RNA component hTR as a template. Because telomerase is inactive in most normal somatic cells, it remains an attractive therapeutic target; however, no telomerase inhibitor has yet demonstrated robust clinical efficacy with acceptable safety. Here we evaluate thiomorpholino oligonucleotides (TMOs) as a new class of antisense oligonucleotides targeting the template region of hTR. TMOs incorporate morpholino rings and phosphorothioate linkages, which enhance nuclease resistance, RNA binding and nuclear uptake. Two anti-hTR TMOs inhibited telomerase activity in vitro with an IC50 below 1 nM, whereas two control TMOs were at least 100-fold less active. HeLa cells treated with anti-hTR TMOs showed progressive telomere shortening, detectable after one week of treatment. Growth inhibition was observed after substantial telomere erosion, and both telomere length and proliferation recovered upon withdrawal of TMOs. These findings establish TMOs as a promising new chemistry for telomerase-targeted therapeutics.

Antisense oligonucleotides (ASOs) inducing exon-skipping during pre-mRNA splicing offer promising treatment for diseases such as Duchenne muscular dystrophy. Recently, dual-targeting ASOs that simultaneously bind two splicing regulatory sequences have been shown to improve exon-skipping efficiency. Current ASOs are designed to interact with target RNAs solely based on Watson-Crick base pairing. Here we report the development of dual-targeting three-dimensional bridge (3D-bridge) ASOs in which tertiary interactions are engineered to increase target-binding affinity and the number of target residues occupied. We designed a 3D-bridge ASO for skipping exon 44 of dystrophin mRNA and biochemically validated its enhanced binding affinity for the target RNA over a similar ASO with the tertiary interactions disrupted. We subsequently optimized the 3D-bridge ASO by varying its ends and ribose chemical modifications using patient-derived induced directly reprogrammed myotubes and identified an LNA/DNA mixmer as the most potent. We further demonstrate enhanced exon-skipping efficacy and potency of the 3D-bridge ASO compared to previously reported ASOs in myotubes differentiated from patient-derived primary myoblasts and MyoD-reprogrammed fibroblasts harboring mutations amenable to reframing through exon 44 skipping. In conclusion, the 3D-bridge ASO technology improves the current dual-targeting design, demonstrating the utility and power of structure-based ASO design methods.

Antibody-oligonucleotide conjugates (AOCs) offer a promising solution to delivery challenges of therapeutic oligonucleotides. However, the relationship between their complex chemical architectures and biological activity remains poorly understood, limiting the development of important structure-function relationships. For siRNA-containing AOCs, increasing the siRNA-to-antibody ratio beyond one (drug-to-antibody ratio, DAR>1) reduces potency, attributed to altered pharmacokinetics arising from increased negative charge density. Here, we investigated whether simple chemical modifications could improve AOC efficacy and mitigate limitations associated with higher DAR. Introduction of a single C16 lipid modification to the siRNA significantly enhanced target gene silencing compared to the unmodified AOC. Extending this modification to a DAR2 architecture, in which two siRNAs are conjugated per antibody, restored the loss of activity associated with increasing DAR from 1 to 2. Notably, at an equivalent siRNA dose (1 mg/kg), the DAR2-C16 AOC requires half the amount of antibody while achieving knockdown comparable to the DAR1-C16 AOC. We also developed a charge-balancing ionizable linker (CBIL) designed to partially compensate for the negative charge of siRNA. Incorporation of the CBIL enhanced target gene silencing in heart and skeletal muscle without a corresponding increase in hepatic activity, resulting in a shift toward greater extrahepatic activity relative to liver. Together, these findings demonstrate that chemical modification of both the siRNA payload and antibody-siRNA linker can be used to tune AOC potency and tissue activity, while enabling higher payload loading without compromising efficacy. These results establish chemical design as an important strategy for expanding the architecture and therapeutic potential of AOCs.

Despite intensive treatment, high-risk neuroblastoma (HRNB) remains a leading cause of cancer-related mortality in children. Current treatment paradigms include multimodal systemic treatments and multi-agent chemotherapy, which is limited by substantial acute and long-term toxicities. Platinum-based chemotherapy is a cornerstone of this treatment but is fraught with side effects and stands to benefit from dose reduction strategies. MicroRNA (miR)-based therapeutics represent an attractive strategy to simultaneously moderate multiple oncogenic pathways, providing a potential avenue to enhance the efficacy of current treatment regimens. However, the development of miR therapeutics has largely relied on chemically synthesized ones, which are limited by issues of inconsistency and poor in vivo stability. Biologically produced, tRNA/pre-miR containing bioengineered miRs (bioRNAs) address these limitations. We investigated the therapeutic potential of bioRNA encoding miR-124 and miR-34a across molecularly distinct HRNB models and evaluated their ability to enhance cisplatin efficacy. Both bioRNAs significantly suppressed neuroblastoma cell viability in vitro, with proteomic analyses demonstrating preferential induction of neuronal differentiation by miR-124 and apoptotic signaling by miR-34a. Combining bioRNA with cisplatin produced robust synergy across multiple HRNB lines, enhancing apoptosis while simultaneously promoting differentiation-associated phenotypes. In vivo, both bioRNAs suppressed tumor growth as monotherapies, while combination with low-dose cisplatin produced the strongest responses across multiple xenograft models with different HRNB subtypes. Notably, low-dose cisplatin combined with bioRNA therapy frequently achieved tumor control comparable to, or greater than, that observed with high-dose cisplatin monotherapy while maintaining favorable tolerability. These findings establish bioRNAs as potent cisplatin sensitizers and support bioRNA-based combination therapy as a strategy for improving HRNB treatment while reducing chemotherapy-associated toxicity in children.

Recombinant vectors derived from adeno-associated viruses (rAAVs) are a mainstay of human gene therapy. rAAVs are produced from plasmids containing transgene cassettes flanked by inverted terminal repeats (ITRs), which form structured DNA elements that stabilize the ends of the single-stranded viral genome and are the only viral sequences required in cis for genome packaging. For decades, it has been recognized that propagation of ITR-containing plasmids can result in deletions and other mutations, prompting the use of specialized bacterial strains, modified growth conditions, and truncated or altered ITRs. Despite these practices, ITR instability remains a persistent source of plasmid heterogeneity. To identify determinants of ITR stability, we evaluated ITR integrity in one of the original cloned AAV2 genome isolates, a reconstructed AAV2 plasmid, and a synthetic rAAV vector containing full-length native AAV2 ITRs. We established a quantitative bioinformatic workflow for analyzing ITR-containing plasmids and virus preparations from raw Oxford Nanopore sequencing data. These experiments showed that ITRs were highly stable during short-term culture, whereas prolonged culture revealed strong positional effects, with preferential loss or mutation of the ITR nearest the plasmid origin of replication. Consistent with this model, a survey of 7,041 sequence-verifiable AAV plasmids from the Addgene repository identified a widely disseminated 11-bp ITR deletion in 4,773 plasmids; among analyzable two-ITR plasmids, this deletion was located in the origin-proximal ITR in 95.3% of cases. Guided by these findings, we constructed a novel rAAV entry vector with stable full-length native AAV2 ITRs that enabled efficient packaging of a 4,750-bp all-in-one CRISPR-Cas9 cassette. Finally, we developed a cell-based strategy to compare the effects of ITR mutations on rAAV genome integration, providing preliminary evidence that ITR sequence variation can influence integration outcomes. Together, these findings show that ITR instability is a preventable, position-dependent property of plasmid architecture and identify ITR integrity as an important variable in rAAV vector design and quality control.

Mitochondrial DNA (mtDNA) base editors (mtBEs) are promising tools for studying and correcting pathogenic mtDNA mutations. However, the application of mtBEs is often hindered by substantial mtDNA-wide off-target editing that accumulates with prolonged mtBE expression resulting from plasmid DNA or viral delivery. To overcome this limitation, we developed mtBE-VLPs, a virus-like-particle (VLP) platform for transiently delivering mtBEs in vitro and in vivo with minimal off-target effects. While canonical protein-packaging VLPs yielded undetectable mtDNA base editing, engineered mRNA-packaging VLPs enabled efficient but transient mtBE cargo delivery. By iteratively engineering mRNA-packaging VLP compositions, we improved mtBE-VLP-mediated base editing efficiencies from less than 1% to greater than 50% across multiple target mtDNA loci in bulk populations of treated cultured cells. To further improve the packaging and delivery of certain mtBEs, we developed a strategy to selectively reduce mtBE cargo expression in VLP producer cells but not transduced cells, which increased VLP-mediated base editing efficiencies for certain mtBEs by 7.1-fold. Compared to plasmid DNA delivery in vitro, mtBE-VLPs exhibited equivalent on-target editing but 23- to 41-fold lower mtDNA-wide off-target editing, highlighting the improved editing specificity offered by transient mtBE delivery. mtBE-VLPs efficiently installed a pathogenic mtDNA mutation in mouse embryonic fibroblasts (88% efficiency) and corrected a pathogenic mtDNA mutation in a human patient-derived cell line (41% efficiency). Additionally, a single subretinal injection of mtBE-VLPs yielded 6-20% (average 12%) mtDNA base editing in the mouse retinal pigment epithelium with minimal mtDNA-wide off-target editing. These findings establish mRNA-packaging mtBE-VLPs as promising vehicles for efficient and precise mitochondrial base editing via transient mtBE delivery.

Myotonic dystrophy type 1 (DM1) is caused by a CTG expansion in the 3' untranslated region of the DMPK gene that results in the expression of expanded CUG RNA which trap splicing factors resulting in widespread alternative splicing dysregulation. A panel of these splicing events, or splicing index (SI), is currently used to measure splicing dysregulation in DM1 patients. Despite significant interest in splicing, little is known about its progression over time in DM1. The objective of this study was to evaluate the changes in SI over 3 years in a well-phenotyped cohort of DM1 participants and identify factors contributing to these changes. RNA was extracted from vastus lateralis (VL) biopsies of 20 DM1 participants taken 3 years apart and the SI score was measured using targeted RNA sequencing. Baseline SI scores correlated with percent predicted muscle strength of the ankle dorsiflexors, knee extensors and hand grip. On average, SI scores worsened over 3 years, but the progression varied markedly among participants. Adult/juvenile phenotypes and lower baseline SI scores were among the factors associated with higher progression of SI scores over time. These findings emphasize the importance of integrating clinical phenotype and baseline molecular severity when interpreting longitudinal SI change, particularly in the context of clinical trials.

Adeno-associated viral (AAV) vectors possess immense potential for gene therapy applications. However, microglia can mount an immune response against AAV vectors. Yet, microglia are therapeutic targets since they play a driving role in the progression of neurodegenerative diseases. Thus, it is critical to understand the cellular processes driving the microglia-mediated immune response against AAV vectors. To this end, we modelled AAV6 induced inflammation upon retinal gene therapy in minipigs. Upon AAV6 administration, the IBA1+ cells demonstrated a morphological transition to the amoeboid form, indicating microglial reactivity. We also observed the invasion of peripheral immune cells in the retina. To elucidate the underlying molecular mechanisms, we transduced human iPSC derived microglia-like cells (iMGLs) in vitro with AAV6 and AAV8 respectively. Only AAV6 transduced iMGLs exhibited morphological features and a transcriptomic signature of microglial reactivity. The magnitude of intracellular AAV6 viral genomes was significantly higher as compared to the AAV8 condition. The elevated levels of intracellular AAV6 genomes induced a DNA damage response in AAV6-transduced iMGLs, which is a key feature of neuroinflammation-linked microglial reactivity. Thus, our work highlights the impact of intracellular viral genome accumulation on microglial reactivity and its implications for retinal gene therapy associated inflammation.

Over the past decade, aptamers have emerged as promising therapeutics, with cancer therapeutics as a major research area. Existing computational methods, however, either predict aptamer-target pairs or design aptamers against a specific target. In this study, we present AntiCapt, a computational method for identifying single-stranded DNA (ssDNA) anticancer aptamers (ACAs) using sequence descriptors and fine-tuned nucleotide language models. The main dataset comprises 1,021 experimentally validated ACAs and an equal number of non-aptamer sequences. Comparative analysis revealed distinct patterns in the nucleotide, dinucleotide, and trinucleotide compositions associated with ACAs. We developed machine learning (ML) models using composition, autocorrelation, binary profiles and structural features. Among these, the best-performing composition-based model achieved an AUC of 0.93 on an independent dataset, while chemical descriptor-and structural feature-based models achieved a maximum AUC of 0.89. ML models using pretrained and fine-tuned NLM embeddings were also developed, with fine-tuned HyenaDNA embeddings achieving the highest performance, with an independent AUC of 0.94. Furthermore, we developed a model for discriminating anticancer aptamers from general aptamers. The best-performing models were integrated into AntiCapt, a web server and a standalone tool for predicting, designing, and genome-scale scanning anticancer aptamers (https://webs.iiitd.edu.in/raghava/anticapt/).

We describe the concept for a new modality to create multi-specific therapeutics that utilizes modified nucleic acids as a scaffold to concatenate multiple warheads (hence called 'catamers'). Catamers are assembled via Watson-Crick interactions into multi-specific molecules from individual components such as ligand-binding modules, protease-cleavage sites, and toxins. Each warhead is covalently bound to an oligonucleotide, which in turn is connected to the catamer scaffold. Post-synthesis of the individual catamer components, they are annealed together such that Watson-Crick base pairs on the oligonucleotides dictate the organization of the warheads on the complete catamer. Notably, catamers are not aptamers, though they can contain aptamers as warheads, along with small molecules and peptides. By design, catamers are intended to address three key problems that have hamstrung the field of multi-specifics: (i) optimization rate; (ii) manufacturing cost; and (iii) unpredictable immunogenicity (Amash et al., 2024 PMID: 39189686). Catamers are purely synthetic and do not require cultured cells to produce. These advantages are based on the underlying design of the catamer and will require experimental validation in future studies. As a proof-of-concept catamer, we focus on a prostate-specific membrane antigen (PSMA)-targeted toxin conjugate. In molecular simulations, this catamer displays structural characteristics to support its intended pharmacology. Importantly, the design addresses one of the key shortcomings of antibody drug-conjugates (ADCs): off-target toxicity caused by release of the toxin after pinocytosis by healthy cells in contact with the blood.

Pitt-Hopkins syndrome (PTHS) is a severe neurodevelopmental disorder caused by haploinsufficient expression of transcription factor 4 (TCF4). Increasing expression from the remaining functional TCF4 allele could provide a mutation-independent strategy for patients with diverse pathogenic variants. We integrated genomic datasets with strand-specific RNA analysis to identify transcribed regions of the TCF4 promoter suitable for targeting by activating double-stranded RNAs (dsRNAs). Screening of overlapping promoter-targeted dsRNAs identified a hotspot for increased TCF4 expression. Activation was retained by a lead dsRNA containing extensive 2'-fluoro, 2'-O-methyl, and phosphorothioate modifications used in therapeutic oligonucleotides. Anti-AGO2 immunoprecipitation showed association with RNA transcribed from the targeted promoter region. dsRNA-mediated activation was associated with increased RNA polymerase II occupancy. These findings establish promoter-targeted dsRNAs as chemically tractable starting points for increasing TCF4 expression and support their investigation as a mutation-independent strategy for haploinsufficient disease.

Safe, efficient gene delivery throughout the CNS remains a central obstacle to treating genetic diseases of the brain and spinal cord. We describe BI-TfR1 CapX, a human transferrin receptor (TfR1)-binding AAV capsid that, after a low intravenous dose in adult humanized TFRC mice, transduced more than 80% of cortical and spinal neurons and ~60% of cortical astrocytes, with reduced distribution and expression in several peripheral tissues relative to AAV9. Unlike other engineered BBB-crossing capsids, CapX bound the CNS vasculature within minutes and a large fraction of its genomes reached parenchymal nuclei within 24 hours. Delivering a Prnp-targeted epigenetic silencer (Prnp-CHARM), CapX reduced brain Prnp mRNA by over 95% requiring 18-fold fewer vector genomes per brain cell than AAV-PHP.eB for 50% lowering. A CapX delivered dual-vector cytosine base editor installed a protein-truncating PRNP stop codon lowering brain prion protein by 80%. These properties make CapX an attractive vehicle for human CNS gene therapy.

Extracellular microRNAs (miRNAs) contribute to metastasis through communication between tumour cells and their microenvironment, yet their sustained, sequence-selective depletion remains challenging. Here we report Programmable RNA-Intercepting Molecular Eraser (PRIME), a membrane-anchored DNA nanomachine that organizes miRNA recognition and catalytic degradation at the cell surface. A double-tetrahedral DNA scaffold positions a programmable recognition hairpin beside RNase H. Target binding generates an RNA/DNA hybrid for RNase H-mediated cleavage, and product release resets the hairpin for subsequent degradation cycles. Membrane-anchored PRIME depleted matched extracellular miRNAs by 70.6-89.4% across lung, breast and cervical cancer cell models. Multi-target PRIME (M-PRIME) inhibited migration by 71.3-96.0% in Transwell assays across these models. To evaluate its therapeutic potential, we established an orthotopic lung-tumour model and an early-intervention breast-cancer lung-colonization model in mice. Aptamer-directed M-PRIME combined with gemcitabine reduced pulmonary tumour burden by 74.5% in established lung tumours and 93.2% in the lung-colonization model. These effects were consistent with PRIME-mediated extracellular miRNA degradation, with circulating target miRNA levels reduced by 77.5-98.7% relative to gemcitabine alone. Together, these findings establish a programmable material strategy for sustained extracellular RNA depletion and support its potential to enhance chemotherapy in preclinical tumour models.

Spinocerebellar ataxia type 3 (SCA3) is most common subtype of autosomal dominant spinocerebellar ataxia worldwide and the most prevalent CAG expansion disorder in the east Asian population, but disease-modifying therapies remain unavailable. SCA3 is caused by the accumulation of polyglutamine- (polyQ-) expanded mutant ataxin-3 (mAtxn3), while the wild-type ataxin-3 (wtAtxn3) plays an important cellular role. Thus, allele-selective clearance of mAtxn3 without affecting wtAtxn3 is highly desired for SCA3 treatment. To achieve this goal, we tested previously reported compounds that have been shown to selectively degrade the Huntingtons disease causing mutant HTT protein by tethering the expanded polyQ to the autophagosome protein LC3. Here, we demonstrated that two of these compounds, AN2 and GW5074, selectively reduced both soluble and aggregated mAtxn3 with expanded polyQ (84Q), but not wtAtxn3, in both cellular and mouse models of SCA3. Mechanistically, both compounds lowered mAtxn3 by enhancing its autophagic degradation without obvious activation of global autophagy. At the molecular level, both compounds increased mAtxn3-LC3 interaction and colocalization to enhance the allele-selectively autophagic degradation of mAtxn3. Phenotypically, both compounds rescued cell viability and ATP content of SCA3 cellular models. In SCA3 patient pluripotent stem cells (iPSCs) derived cortical neurons, both compounds allele-selectively reduced mAtxn3 and partially rescued neurite shortening. Importantly, in a well-established SCA3 transgenic mouse model (MJD84.2), intracerebroventricular, intraperitoneal, and oral administration allele-selectively reduced mAtxn3 in multiple brain regions and rescued motor function deficits. Oral dosing achieved nanomolar cerebellar exposure and showed no overt liver, kidney, or glial toxicity over 28 days. Analyses of 1303 Chinese patients with SCA3 and ATXN3 constructs of different polyglutamine lengths further supported the compounds polyQ length-dependent activity with relative sparing of normal-length ataxin-3. Together, these findings provide preclinical proof of concept that utilizing orally available small molecule compounds to allele-selectively enhance mAtxn3 autophagic degradation for SCA3 treatment. One-sentence summarySmall-molecule autophagosome-tethering compounds selectively lower mutant ataxin-3 through an LC3- and autophagy-dependent mechanism and improve disease-related phenotypes in preclinical models of SCA3.

Therapeutic siRNAs are a major clinical modality for hepatic gene silencing, but efficient extrahepatic delivery and multi-gene modulation remain significant barriers. Nucleic acid nanotechnology offers programmable assembly, but conventional structures suffer from enzymatic instability in vivo . Here we report fully chemically modified RNA nanostructures (FMRNs): a vehicle-free platform entirely composed of stabilized therapeutic nucleic acids that integrate structural precision with metabolic durability. Following systemic administration, FMRNs exhibit enhanced pharmacokinetics and extrahepatic accumulation, with in vivo behavior influenced greatly by hydrodynamic size rather than molecular weight. Using triangular and square geometries, we demonstrate programmable control over siRNA stoichiometry to achieve sustained, simultaneous silencing of up to four genes from a single entity. Nanostructure assembly alone drives productive delivery, especially to heart and muscle, matching lipophilic conjugation. Furthermore, cerebrospinal fluid administration reveals that larger FMRNs improve central nervous system distribution and retention revealing physicochemical parameters that impact brain exposure. FMRNs establish a modular and effective platform combining improved pharmacokinetics, extrahepatic delivery, and multi-gene silencing for complex diseases.

Polymer modification of antibodies has attracted attention for enhancing antibody functionality. Modification with polyethylene glycol (PEG) or biopolymers such as antibody-oligonucleotide conjugates has been investigated. Although direct effects at the modification site have been understood, distal effects of modifications on intrinsic antibody functions such as antigen-binding and Fc receptor-binding activities remain poorly characterized. In this study, we prepared site-specifically PEGylated trastuzumab to evaluate the effects of the modification site and the size of PEG chains on antibody functions. Reporter gene assays revealed a significant reduction in antibody-dependent cell cytotoxicity (ADCC) activity in a site- and size-dependent manner. Both the reduction in interaction with the antigen and Fc{gamma}RIIIa were observed in a size-dependent manner. Interestingly, the effect of the modification site was only observed for ADCC activity, which suggests that the higher-order structure of the modified antibody plays a critical role in effector function. These results provide molecular design guidelines for the polymer modification of antibodies.

Mislocalization and aggregation of the RNA-binding proteins (RBPs) FUS and TDP-43 are pathological hallmarks of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), contributing to combined loss- and gain-of-function toxicity. Here, we present a protein engineering strategy that appends optimized anti-aggregation motifs to FUS and TDP-43, thereby enhancing their nuclear localization and solubility, and enabling functional replacement of disease-associated proteins. We show that these engineered chimeric RBPs reduce levels of aggregation-prone endogenous proteins through autoregulatory mechanisms. In addition, chimeric FUS and TDP-43 recapitulate key nuclear functions, including DNA repair and mRNA processing. Notably, chimeric FUS restores neurite outgrowth in diseased iPSC-derived neurons, while chimeric TDP-43 suppresses cryptic exon inclusion in patient-derived fibroblasts. Collectively, these results demonstrate that engineered chimeric RBPs can rebalance RBP homeostasis by simultaneously addressing protein aggregation and mislocalization, thus mitigating RBP-associated loss- and gain-of-function toxicity, highlighting a generalizable strategy for therapeutic protein replacement in neurodegenerative disease.

Cationic lipid nanoparticles have demonstrated unique potential for extrahepatic mRNA delivery, particularly enabling selective targeting of the pulmonary endothelium. However, their translational development has been hampered by reports of infusion-related immune reactions and innate immune system activation, most notably transient complement activation. Here, we present a case study illustrating the discovery and translational advancement of a selected cationic LNP into non-human primates (NHPs) for initial pharmacokinetic assessment and evaluation of potential immunostimulatory side effects. We show surface charge dependent organ-selective expression of reporter mRNAs from different LNPs in vivo. An mRNA encoding the Tie2 agonist COMP-Angl, was formulated with LNP002, and respective pharmacokinetic and pharmacodynamic readouts were analyzed in two independent non-human primate studies. Notably, dose-dependent transient complement activation could be abrogated by extending the infusion time. Finally, we identified the blood-borne pharmacodynamic biomarker PDGFB for LNP002/mRNA-76 treatment reflecting activated Tie2-signalling in healthy pulmonary endothelium in vivo supported by single cell sequencing and cluster-alignment of downstream effector genes with the same spatial profile as the delivered mRNA.