# RNA editing (ADAR) therapeutics Engineered oligonucleotides that recruit the cell's endogenous ADAR enzymes to rewrite a pathogenic adenosine to inosine on disease transcripts — a reversible, titratable alternative to DNA editing now in clinical validation, with Wave's WVE-006 (AATD, RestorAATion-2) the lead asset and ProQR's Axiomer platform delivering the first clinical proof of mechanism. Source: https://en.bioecon.ru/technology/rna-editing-adar-therapeutics/ Updated: 2026-08-18 ## Overview and value chain Markers: [EC: FDA orphan-drug designation + accelerated-approval pathway; Directive 2001/83/EC | OECD: Bio-pharma | Regulator: FDA (USA), EMA (European Union), NMPA (China)] RNA editing therapeutics correct disease-causing transcripts at the RNA level rather than in the genome. Engineered oligonucleotides — Wave's AIMers, Korro's OPERA guides, ProQR's Axiomer EONs, HuidaGene's arRNAs — recruit the cell's endogenous adenosine deaminase acting on RNA (ADAR) enzymes to convert a pathogenic adenosine to inosine (A-to-I, read as guanosine), repairing mutant mRNA without any permanent change to the DNA. Because the edit is made on the transcript, it is reversible and dose-titratable, with no bystander edits, no indels and no lasting genome alteration — the safety advantages the modality holds over DNA base editing. The field's lead asset, Wave's WVE-006 (a GalNAc-conjugated AIMer for alpha-1 antitrypsin deficiency, AATD), generated wild-type M-AAT at 64% of total AAT and cut toxic Z-AAT by 71% in the RestorAATion-2 trial, reaching 11.9 µM total AAT with editing sustained for at least three months after the last dose; ProQR's AX-0810 then delivered the first clinical validation of an RNA-editing platform with an 8-fold NTCP target-engagement signal, and Korro's KRRO-111 achieved more than 90% SERPINA1 editing in vivo. Delivery is dominated by subcutaneous GalNAc conjugation that routes the oligo to hepatocytes via ASGPR, avoiding lipid nanoparticles; no RNA-editing drug is approved yet, and FDA feedback on an accelerated-approval pathway for WVE-006 is expected mid-2026. The key directions of RNA editing therapeutics are: 1. **AATD RNA editors (AATD Editor):** GalNAc ADAR-recruiting oligonucleotides that repair the SERPINA1 Z-allele transcript, restoring protective M-AAT and clearing toxic Z-AAT in the liver — Wave (WVE-006), Korro (KRRO-110, KRRO-111). 2. **Liver and metabolic editors (Metabolic Editor):** RNA editing of hepatocyte transporters and metabolic enzymes beyond AATD — ProQR (AX-0810/AX-0811 on NTCP for cholestatic liver disease, AX-2911 on PNPLA3 for MASH). 3. **ADAR-recruitment platforms (Editing Platform):** the guide-RNA and chemically modified oligonucleotide chemistries that recruit endogenous ADAR1/ADAR2 without delivering any exogenous enzyme — Wave AIMer, Korro OPERA, ProQR Axiomer, HuidaGene LEAPER. 4. **CNS and rare-disease editors (CNS Editor):** extension of A-to-I editing to neuronal and rare-genetic targets through partnered programs — ProQR (AX-2402 for Rett syndrome MECP2, with the Rett Syndrome Research Trust; Eli Lilly CNS collaboration). ### Sectoral value chain ``` [pathogenic A-to-I target on mRNA] ──> [ADAR-recruiting oligo (AIMer/EON/arRNA) design + synthesis] ──> [GalNAc-conjugated subcutaneous editor] │ (endogenous ADAR A-to-I edit, reversible) │ ▼ [clinical candidate] <─── [editing PD/PK + Phase 1-2 trials] <─────┘ ``` ### Value chain levels | Level | Description | Key inputs/outputs | |:---|:---|:---| | **Target & SNV selection** | identify a pathogenic G-to-A (A-to-I-correctable) transcript variant and a tractable ADAR-recruitment site | **In:** disease biology.
**Out:** editable SNV. | | **arRNA/EON design** | engineer the ADAR-recruiting oligonucleotide (AIMer/EON/arRNA) with stereopure and bulge chemistry | **In:** target sequence.
**Out:** editing oligo. | | **GalNAc conjugation & CMC** | GalNAc conjugation for ASGPR hepatocyte uptake, stereopure oligonucleotide GMP synthesis | **In:** oligo chemistry.
**Out:** drug substance. | | **Preclinical & clinical** | editing-efficiency and PK studies, IND filing, Phase 1-2 human trials | **In:** drug, subjects.
**Out:** clinical data. | | **Regulatory & approval** | NDA (US) / MAA (EU) as an oligonucleotide therapeutic, orphan-drug and accelerated-approval pathways | **In:** data, dossier.
**Out:** approval. | | **Launch & PV** | market access and post-market pharmacovigilance of a reversible-edit drug | **In:** approval, field.
**Out:** revenue, safety. | Cross-cutting technologies of the sector: - **Endogenous ADAR recruitment (ADAR Recruitment):** all four platforms recruit the cell's own ADAR1/ADAR2 via a guide oligo, avoiding exogenous-protein delivery and so lowering cargo size and immunogenicity versus CRISPR-base-editor proteins. - **GalNAc hepatocyte delivery (GalNAc Delivery):** subcutaneous GalNAc conjugation routes the editor to hepatocytes through the asialoglycoprotein receptor, enabling liver-directed A-to-I editing without lipid nanoparticles and supporting infrequent (monthly or longer) dosing. - **Reversible, titratable editing (Reversible Editing):** because the edit sits on the transcript and not the genome, RNA editing is transient and dose-adjustable, with no bystander edits or permanent genome change — the central safety differentiator versus DNA editing. --- ## US The US leads RNA-editing therapeutics clinically, with the field's two most advanced AATD programs — Wave's WVE-006 in Phase 1b/2a and Korro's OPERA platform — both run from Cambridge, MA, under an FDA framework built on orphan-drug designation and the accelerated-approval pathway. ### Wave, Korro, FDA - **Wave Life Sciences:** WVE-006, a GalNAc-conjugated AIMer for AATD, is the modality's lead asset; RestorAATion-2 data (May 2026) showed 64% wild-type M-AAT, a 71% reduction in toxic Z-AAT, 11.9 µM total AAT on 200 mg biweekly dosing (13.6 µM on 400 mg monthly), and editing sustained at least three months after the last dose, with no liver toxicities; FDA feedback on an accelerated-approval pathway is expected mid-2026. - **Korro Bio:** the OPERA (Oligonucleotide Promoted Editing of RNA) platform underpins KRRO-110 (in the REWRITE Phase 1/2a study, with FDA orphan-drug designation granted in March 2025) and the newly selected development candidate KRRO-111, which achieved more than 90% SERPINA1 transcript editing and roughly 90% repaired functional AAT protein in a PiZZ mouse model; the company held $157.1M in cash and marketable securities at 31 March 2026, with a runway into H2 2028. - **FDA framework:** RNA-editing oligonucleotides are reviewed under the FDA's oligonucleotide-therapeutics pathway, with orphan-drug designation and the accelerated-approval route available for AATD (a rare disease affecting fewer than 200,000 people in the US); WVE-006's mid-2026 regulatory feedback is the modality's first such checkpoint. --- ## CN China's RNA-editing strength is foundational rather than commercial: Wensheng Wei's group at Peking University and Changping Laboratory originated the LEAPER platform, whose 2026 LEAPER 3.0 iteration is the field's leading structure-guided guide-RNA design, with HuidaGene as the translation vehicle. ### HuidaGene, LEAPER, NMPA - **HuidaGene:** is commercializing the LEAPER (Leveraging Endogenous ADAR for Programmable Editing of RNA) platform from Wei's PKU lab; LEAPER uses a single engineered ADAR-recruiting RNA (arRNA) to direct endogenous ADAR to a target adenosine, with no exogenous enzyme and therefore low immunogenicity and a small delivery payload. - **LEAPER lineage:** LEAPER 1.0 was published in Nature Biotechnology in 2019 (linear arRNA), LEAPER 2.0 in 2022 introduced circular circ-arRNA for higher editing efficiency and lower off-target editing, and LEAPER 3.0 (Cell, 10 June 2026) uses AlphaFold 3 structural prediction to design dual-bulge arRNAs that expand the set of editable sites and eliminate bystander editing. - **NMPA framework:** RNA-editing therapeutics are reviewed under the NMPA's oligonucleotide and biologics framework; the LEAPER platform's progress rests on National Natural Science Foundation of China funding (grants 82341207 and 31930016) and Beijing municipal science-and-technology support, with clinical translation still ahead of the US leaders. --- ## EU Europe's role in RNA editing is concentrated in ProQR Therapeutics (Leiden, NL), whose Axiomer platform delivered the first clinical validation of an RNA-editing oligonucleotide and is scaled through a deepening Eli Lilly partnership. ### ProQR, Axiomer, EMA - **ProQR Therapeutics:** the Axiomer platform uses ADAR-recruiting editing oligonucleotides (EONs); AX-0810, a GalNAc-conjugated EON modulating NTCP for cholestatic liver disease, produced the first clinical validation of the platform in 2026 — a dose-dependent up to 8-fold rise in total bile acids at 6 mg/kg (above the 2-fold target-engagement threshold) with an estimated half-life of about 8 weeks and no serious adverse events; the follow-on AX-0811 has a clinical-trial application planned mid-2026, and development candidates AX-2402 (Rett syndrome) and AX-2911 (MASH) extend the pipeline. - **Eli Lilly partnership:** Lilly has been tied to the Axiomer platform since 2021 (liver and nervous-system targets), expanded in 2022, with ProQR eligible for up to about $3.75bn in milestones plus royalties; Lilly maintained its pro-rata ownership in ProQR's $59.2M June 2026 raise (buying about $9.2M of shares alongside a $50M public offering at $1.81 per share). - **EMA framework:** RNA-editing oligonucleotides will be reviewed as MAA drugs by the European Medicines Agency under Directive 2001/83/EC; ProQR divested its late-stage ophthalmic assets (sepofarsen, ultevursen) in 2023 to focus entirely on Axiomer, and no RNA-editing drug is yet EU-approved. --- ## Leading companies and research institutes | Company / Institute | Country | Key products / platforms | Tech features | Status 2026 | |:---|:---|:---|:---|:---| | **Wave Life Sciences** | 🇺🇸 USA | *WVE-006 (AATD)* | GalNAc AIMer, A-to-I editor | operating | | **Korro Bio** | 🇺🇸 USA | *KRRO-110 / KRRO-111 (AATD)* | OPERA ADAR-recruiting editor | operating | | **ProQR Therapeutics** | 🇳🇱 Netherlands | *AX-0810 (NTCP)* | Axiomer EON platform | operating | | **HuidaGene** | 🇨🇳 China | *LEAPER platform* | arRNA ADAR-recruiting editor | research | --- ## Tech stack and innovations The stack pairs ADAR-recruiting oligonucleotide chemistry with GalNAc hepatocyte delivery and structure-guided guide-RNA design, yielding a reversible A-to-I edit on a disease transcript. 1. **ADAR-recruiting oligonucleotides (Editing Oligo):** - Wave's AIMer (stereopure), Korro's OPERA, ProQR's Axiomer EON and HuidaGene's arRNA are chemically modified oligos that recruit endogenous ADAR1/ADAR2 to a target adenosine; WVE-006 generated 64% M-AAT with a 71% Z-AAT reduction and editing sustained at least three months, while KRRO-111 reached more than 90% SERPINA1 transcript editing and roughly 90% repaired AAT protein in vivo. 2. **GalNAc hepatocyte delivery (GalNAc Delivery):** - subcutaneous GalNAc conjugation targets the asialoglycoprotein receptor on hepatocytes, enabling liver-directed editing without lipid nanoparticles; AX-0810 showed an 8-fold NTCP target-engagement signal at 6 mg/kg with an approximately 8-week half-life, and WVE-006 is dosed 200 mg biweekly or 400 mg monthly with a dynamic AAT response (up to 20.6 µM total AAT during an acute-phase response). 3. **Structure-guided arRNA design (Guide Design):** - rational engineering of the ADAR-recruiting guide to expand the editable sequence space and remove bystander edits; HuidaGene's LEAPER 3.0 (Cell, 2026) uses AlphaFold 3 to model the ADAR1/ADAR2–double-stranded-RNA interface and introduces inner and outer bulge structures that confine catalysis to the target adenosine. --- ## Value chains and production pipelines ### Industrial pipeline of an ADAR RNA-editing therapeutic (NDA / MAA, Directive 2001/83/EC) ``` ┌───────────────────────────┐ ┌───────────────────────────┐ │ 1. Target & SNV selection │ ───> │ 2. arRNA/EON design │ └───────────────────────────┘ └───────────────────────────┘ │ ▼ ┌───────────────────────────┐ ┌───────────────────────────┐ │ 4. Preclinical & clinical │ <─── │ 3. GalNAc conjugation & │ └───────────────────────────┘ │ CMC │ │ └───────────────────────────┘ ▼ ┌───────────────────────────┐ ┌───────────────────────────┐ │ 5. Regulatory & approval │ ───> │ 6. Launch & PV │ └───────────────────────────┘ └───────────────────────────┘ ``` #### Stage 1: Target and SNV selection A pathogenic G-to-A transcript variant correctable by A-to-I editing is identified (for example the SERPINA1 Z-allele in AATD or the NTCP transporter in cholestatic liver disease), together with an ADAR-recruitment-compatible sequence context around the target adenosine. #### Stage 2: arRNA/EON design An ADAR-recruiting oligonucleotide — an AIMer (Wave), OPERA guide (Korro), Axiomer EON (ProQR) or arRNA (HuidaGene) — is engineered with stereopure chemistry and, in LEAPER 3.0, dual-bulge structures that position endogenous ADAR on the target adenosine while suppressing bystander editing. #### Stage 3: GalNAc conjugation and CMC The editing oligo is conjugated to a GalNAc ligand for ASGPR-mediated hepatocyte uptake and manufactured under stereopure oligonucleotide GMP, yielding a subcutaneously delivered drug substance that avoids lipid-nanoparticle formulation. #### Stage 4: Preclinical and clinical Editing-efficiency, PK and safety studies support IND filing and first-in-human trials; WVE-006 is in the RestorAATion-2 Phase 1b/2a trial (11.9 µM total AAT, 71% Z-AAT reduction, editing held at least three months), KRRO-110 is in the REWRITE Phase 1/2a study, and AX-0810 produced the first clinical target-engagement validation of an RNA-editing platform (8-fold bile-acid response at 6 mg/kg). #### Stage 5: Regulatory and approval A NDA (US) or MAA (EU) is filed as an oligonucleotide therapeutic under Directive 2001/83/EC, with orphan-drug designation and the accelerated-approval pathway available for rare indications such as AATD; FDA feedback on an accelerated-approval route for WVE-006 is expected mid-2026. #### Stage 6: Launch and pharmacovigilance Following approval, the reversible-edit drug launches under the oligonucleotide pharmacovigilance regime, with real-world monitoring of editing durability and re-dosing interval that the modality has not yet seen at scale, no RNA-editing drug being yet approved.