RESUMO
Understanding small interfering RNA (siRNA) fraction unbound (f u) in relevant physiologic compartments is critical for establishing pharmacokinetic-pharmacodynamic relationships for this emerging modality. In our attempts to isolate the equilibrium free fraction of N-acetylgalactosamine-conjugated siRNA using classic small-molecule in vitro techniques, we found that the hydrodynamic radius was critical in determining the size exclusion limit requirements for f u isolation, largely validating the siRNA "rigid rod" hypothesis. With this knowledge, we developed an orthogonally validated 50 kDa molecular-mass cutoff ultrafiltration assay to quantify f u in biologic matrices including human, nonhuman primate, rat, and mouse plasma, and human liver homogenate. To enhance understanding of the siRNA-plasma interaction landscape, we examined the effects of various common oligonucleotide therapeutic modifications to the ribose and helix backbone on siRNA f u in plasma (f u,plasma) and found that chemical modifications can alter plasma protein binding by at least 20%. Finally, to gain insight into which specific plasma proteins bind to siRNA, we developed a qualitative screen to identify binding "hits" across a panel of select purified human plasma proteins.
Assuntos
Acetilgalactosamina/farmacocinética , Proteínas Sanguíneas/metabolismo , Fígado/metabolismo , RNA Interferente Pequeno/farmacocinética , Acetilgalactosamina/química , Adulto , Animais , Feminino , Humanos , Macaca fascicularis , Camundongos , Ligação Proteica , RNA Interferente Pequeno/química , RatosRESUMO
Antisense oligonucleotides (ASOs) are promising therapeutics for treating various neurological disorders. However, ASOs are unable to readily cross the mammalian blood-brain barrier (BBB) and therefore need to be delivered intrathecally to the central nervous system (CNS). Here, we engineered a human transferrin receptor 1 (TfR1) binding molecule, the oligonucleotide transport vehicle (OTV), to transport a tool ASO across the BBB in human TfR knockin (TfRmu/hu KI) mice and nonhuman primates. Intravenous injection and systemic delivery of OTV to TfRmu/hu KI mice resulted in sustained knockdown of the ASO target RNA, Malat1, across multiple mouse CNS regions and cell types, including endothelial cells, neurons, astrocytes, microglia, and oligodendrocytes. In addition, systemic delivery of OTV enabled Malat1 RNA knockdown in mouse quadriceps and cardiac muscles, which are difficult to target with oligonucleotides alone. Systemically delivered OTV enabled a more uniform ASO biodistribution profile in the CNS of TfRmu/hu KI mice and greater knockdown of Malat1 RNA compared with a bivalent, high-affinity TfR antibody. In cynomolgus macaques, an OTV directed against MALAT1 displayed robust ASO delivery to the primate CNS and enabled more uniform biodistribution and RNA target knockdown compared with intrathecal dosing of the same unconjugated ASO. Our data support systemically delivered OTV as a potential platform for delivering therapeutic ASOs across the BBB.
Assuntos
Barreira Hematoencefálica , Oligonucleotídeos Antissenso , RNA Longo não Codificante , Receptores da Transferrina , Animais , Oligonucleotídeos Antissenso/farmacocinética , Oligonucleotídeos Antissenso/administração & dosagem , Barreira Hematoencefálica/metabolismo , Receptores da Transferrina/metabolismo , Humanos , RNA Longo não Codificante/metabolismo , RNA Longo não Codificante/genética , Camundongos , Transporte Biológico , Macaca fascicularis , Técnicas de Silenciamento de Genes , Distribuição TecidualRESUMO
The phenoxyalkylimidazoles (PAI) are an attractive chemical series with potent anti-tubercular activity targeting Mycobacterium tuberculosis respiration. Our aim was to determine if the PAI compounds are subject to efflux. Two analogs containing an oxadiazole had improved potency in the presence of the efflux inhibitors reserpine and carbonyl cyanide m-chlorophenylhydrazine, whereas the potency of analogs with a diazole was not affected.
Assuntos
Mycobacterium tuberculosis/efeitos dos fármacos , Oxidiazóis/farmacologia , Fenóis/farmacologia , Antituberculosos/farmacologia , Proteínas de Bactérias/efeitos dos fármacos , Carbonil Cianeto m-Clorofenil Hidrazona/metabolismo , Carbonil Cianeto m-Clorofenil Hidrazona/farmacologia , Humanos , Isoniazida/química , Isoniazida/farmacologia , Proteínas de Membrana Transportadoras/efeitos dos fármacos , Testes de Sensibilidade Microbiana/métodos , Oxidiazóis/química , Fenóis/química , Reserpina/metabolismo , Reserpina/farmacologiaRESUMO
Oligonucleotide therapeutics use short interfering RNA (siRNA) or antisense oligonucleotide (ASO) molecules to exploit endogenous systems-neutralizing target RNA to prevent subsequent protein translation. While the potential clinical application is vast, delivery efficiency and extrahepatic targeting is challenging. Bioanalytical assays are important in building understanding of these complex relationships. The literature currently lacks description of robust and sensitive methods to measure siRNA and ASOs in complex biological matrices. Described herein is a non-enzymatic hybridization-based immunoassay that enables quantification of individual siRNA strands (antisense or sense) in serum, urine, bile, and liver and kidney homogenates. Assay utility is also demonstrated in ASOs. The assay improves upon previous works by abolishing enzymatic steps and further incorporating Locked Nucleic Acid (LNA) nucleotide modifications to increase analyte hybridization affinity and improve sensitivity, specificity, and robustness. We report an assay with an ultrasensitive dynamic range of 0.3 to 16,700 pM for siRNA in serum. The assay was submitted to full qualification for accuracy and precision in both serum and tissue matrices and assay performance was assessed with single and mixed analytes. The reliable LNA-hybridization-based approach removes the need for matrix sample extraction, enrichment or amplification steps which may be impeded by more advanced chemical modifications.
Assuntos
Imunoensaio , Ácidos Nucleicos/análise , RNA Interferente Pequeno/metabolismo , Animais , Humanos , Camundongos , Oligonucleotídeos , Ratos , Ratos Sprague-DawleyRESUMO
After two decades teetering at the intersection of laboratory tool and therapeutic reality, with two siRNA drugs now clinically approved, this modality has finally come into fruition. Consistent with other emerging modalities, initial proof-of-concept efforts concentrated on coupling pharmacologic efficacy with desirable safety profiles. Consequently, thorough investigations of siRNA absorption, distribution, metabolism, and excretion (ADME) properties are lacking. Advancing ADME knowledge will aid establishment of in vitro-in vivo correlations and pharmacokinetic-pharmacodynamic relationships to optimize candidate selection through discovery and translation. Here, we outline the emerging siRNA design principles and discuss the consequences for siRNA disposition and biotransformation. We propose a conceptual framework for siRNA ADME evaluation, contextualizing the site of biotransformation product formation with PK-PD modulation, and end with a discussion around safety and regulatory considerations and future directions for this modality.
Assuntos
Biotransformação , Desenho de Fármacos , Desenvolvimento de Medicamentos , Avaliação Pré-Clínica de Medicamentos , Preparações Farmacêuticas/química , RNA Interferente Pequeno/química , Animais , Humanos , Preparações Farmacêuticas/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/farmacocinética , Distribuição TecidualRESUMO
There has been a renewed interest in therapeutic small interfering RNAs (siRNAs) over the past few years. This is particularly the result of successful and efficient delivery of N-acetylgalactosamine (GalNAc)-conjugated siRNAs to the liver. In general, the lead selection process for siRNA drugs is faster and more straightforward than traditional small molecules. Nevertheless, many siRNAs of different sequences and chemical modification patterns must still be evaluated before arriving at a final candidate. One of the major difficulties in streamlining this workflow is the well-known phenomenon that the in vitro data obtained from oligonucleotides transfected into cells are not directly predictive of their in vivo activity. Consequently, all oligonucleotides with some degree of in vitro activity are typically screened in vivo before final lead selection. Here, we demonstrate that the stability of liver-targeting GalNAc-conjugated siRNAs in a mouse liver homogenate shows an acceptable correlation to their in vivo target knockdown efficacy. Therefore, we suggest the incorporation of an in vitro liver homogenate stability assay during the lead optimization process for siRNAs. The addition of this assay to a flow scheme may decrease the need for animal studies, and it could bring cost savings and increase efficiency in siRNA drug development.
RESUMO
The potential repertoire of short interfering RNA (siRNA) therapeutics is expanding as targeting strategies evolve. One approach to enable organ-specific delivery has been to directly conjugate siRNA to a monoclonal antibody (siRNA-mAb), analogous to antibody-drug conjugates. Detection of intact siRNA-mAb conjugates presents a bioanalytical challenge given that certain synthetic nucleotide chemical modifications and low-temperature requirements render common oligonucleotide detection assays, such as reverse transcription-polymerase chain reaction, incompatible with the immunoassay component. To circumvent these issues, we developed a triplex-forming oligonucleotide ELISA using locked nucleic acid (LNA) containing oligonucleotide probes. We demonstrate that the incorporation of these LNAs allow for an enrichment and immobilization of siRNA directly conjugated to an antibody at nondenaturing temperatures. Without further requirement for extraction or amplification, we can sensitively and specifically detect intact siRNA-mAb conjugates in complex matrices such as serum and tissue homogenate.
Assuntos
Anticorpos Monoclonais/isolamento & purificação , Ensaio de Imunoadsorção Enzimática/métodos , Oligonucleotídeos/isolamento & purificação , RNA Interferente Pequeno/isolamento & purificação , Anticorpos Monoclonais/genética , Anticorpos Monoclonais/imunologia , Humanos , Imunoconjugados/genética , Imunoconjugados/imunologia , Oligonucleotídeos/genética , Oligonucleotídeos/imunologia , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/imunologiaRESUMO
Despite the exquisite potential of siRNA as a therapeutic, the mechanism(s) responsible for the robust indirect exposure-response relationships have not been fully elucidated. To understand the siRNA properties linked to potent activity, requires the disposition of siRNA to be characterized. A technical challenge in the characterization is the detection and quantitation of siRNA from biological samples. Described herein, a Locked Nucleic Acid (LNA) Hybridization-Ligation ECL ELISA was designed for ultra-sensitive quantification of both sense and antisense strands of siRNA independent of structural modifica-tions. This assay was applied to measure siRNA in serum and tissue homogenate in preclinical species. We observed rapid clearance of siRNA from the systemic circulation which contrasted the prolonged accumulation within the tissue. The assay was also able to distinguish and quantify free siRNA from RNA-induced silencing complex (RISC) and Argonaute 2 (Ago2) associated with therapeutic siRNA. We utilized an orthogonal method, LC-MS, to investigate 3' exonuclease activity toward the antisense strand metabolism. Taken together, we have demonstrated that the LNA Hybridization-Ligation ECL ELISA is arobust analytical method with direct application to measuring the exposure of siRNA therapeutics seamlessly across biological matrices.