RNA Editing Breakthrough
ProQR Reports Positive Phase 1 Data for AX-0810, Validating RNA Editing Platform
Key Points
AX-0810 is a GalNAc-conjugated, subcutaneously administered Axiomer RNA editing oligonucleotide designed to selectively modulate the NTCP transporter.
The Phase 1 multiple-ascending-dose study enrolled 33 healthy volunteers, with 24 receiving AX-0810 and 9 receiving placebo across the 3 mg/kg, 6 mg/kg, and 9 mg/kg cohorts.
ProQR characterized the AX-0810 data as the first clinical validation of its Axiomer RNA editing platform, highlighting the potential for disease-modifying effects in biliary atresia and related cholestatic diseases.
The company plans to advance AX-0811, a next-generation NTCP-targeting RNA editing oligonucleotide, and intends to submit a Clinical Trial Application to progress into later-stage studies, with patient follow-up through the planned 12-week period.
ProQR Therapeutics announced positive Phase 1 data for AX-0810, its first RNA editing drug, showing an eightfold increase in serum bile acids in healthy volunteers — four times the company's own target, according to Nasdaq. The result marks what CEO Daniel de Boer called "the first clinical validation" of ProQR's Axiomer RNA editing platform, a technology designed to change how genes behave without permanently altering DNA.
The news landed alongside a $59.2 million capital raise, including a $9.2 million private placement by partner Eli Lilly, signaling continued institutional confidence in the approach, according to BriefGlance.
AX-0810 Clears Its Key Hurdle with Room to Spare
The Phase 1 study enrolled 33 healthy volunteers — 24 on AX-0810, 9 on placebo — across three dose levels: 3, 6, and 9 mg/kg, according to QuiverQuant. ProQR set a 2-fold rise in serum bile acids as its bar for meaningful target engagement. The 6 mg/kg cohort hit 8-fold. That result, Chief Medical Officer Cristina Lopez Lopez said, showed "concordant responses across all three predefined biomarkers," providing "compelling clinical target engagement evidence."
The drug also drove changes in bile acid profiles, TUDCA markers, and increased urinary excretion of conjugated bile acids, according to TipRanks. Together, those signals confirm that AX-0810 is doing its job: reducing the liver's uptake of toxic bile acids and routing them safely out through urine. Safety was clean — zero serious adverse events and zero cases of pruritus, a common side effect in liver drugs.
How RNA Editing Works and Why NTCP Is the Target
AX-0810 uses ProQR's Axiomer platform to recruit the body's own ADAR enzymes. Those enzymes convert a single genetic letter — adenosine to inosine — inside a RNA molecule. The cell reads inosine as guanosine, effectively changing a protein's behavior without touching DNA. Think of it as correcting a typo in a working draft, rather than rewriting the master copy.
The target is NTCP, a transporter that pulls bile acids from the blood into the liver. In cholestatic diseases like biliary atresia — a rare condition affecting roughly 1 in 8,000 to 18,000 newborns — bile flow is blocked, and toxic bile acids build up. AX-0810 mimics a naturally protective genetic variant called Q68R to dial down NTCP activity, according to GuruFocus. Biliary atresia is the leading cause of pediatric liver transplants worldwide.
An Eight-Week Half-Life Points Toward Infrequent Dosing
Pharmacokinetic data showed AX-0810 has a half-life of roughly eight weeks, according to QuiverQuant. That means the drug stays active in the body for a long time after a single subcutaneous injection. The implication is significant: patients may eventually need only once-monthly or even less frequent dosing. That kind of schedule is far easier to manage than daily pills, especially for children.
Eli Lilly SVP Andrew Adams said his company has "conviction that RNA editing can be an important alternative to other more permanent therapies," a statement that carries weight given Lilly's original $50 million upfront deal in 2021 and up to $3.75 billion in potential milestones. Lilly's decision to join the private placement in June 2026 underlines that view, according to BriefGlance.
Next Steps: AX-0811, Phase 2, and a Race to the Clinic
ProQR plans to submit a Clinical Trial Application for AX-0811, a next-generation NTCP candidate, in mid-2026, according to TipRanks. AX-0811 is designed for higher potency than AX-0810. A Phase 2 study in biliary atresia is also in the works, with an investigator-initiated pediatric trial planned for China in H1 2027. Patient follow-up for the current Phase 1 study continues through 12 weeks.
The $59.2 million raise extends ProQR's cash runway through mid-2027, starting from a base of €81.1 million on hand as of March 31, 2026, according to BriefGlance. Analysts at Leerink Partners and TipRanks carry Buy ratings with price targets of $12 to $14. One note of caution: some observers point out that ProQR has not yet disclosed an explicit editing efficiency figure — the actual percentage of RNA successfully changed — unlike rival Wave Life Sciences, which reported roughly 30% editing in human liver cells.
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