Vico Therapeutics Announces First Patient Dosed in Phase 1/2a Clinical Trial of VO659 in Huntington’s Disease and Spinocerebellar Ataxia Types 1 and 3 

Apr 3, 2023 | Press Release

  • VO659 is the only clinical-stage candidate targeting the CAG repeat expansion that causes these diseases
  • VO659 was designed to preferentially reduce mutant HTT and spare wild-type HTT
  • Phase 1/2a basket trial design and preclinical VO659 data to be presented at CHDI Foundation’s 18th Annual Huntington’s Disease Therapeutics Conference

LEIDEN, Netherlands, April 3, 2023 /PRNewswire/ — Vico Therapeutics B.V., a clinical-stage genetic medicines company developing therapies for severe neurological diseases, today announced that the first patient has been dosed in a Phase 1/2a clinical study evaluating VO659 for the treatment of Huntington’s disease (HD), spinocerebellar ataxia type 1 (SCA1) and type 3 (SCA3). VO659 is an antisense oligonucleotide (ASO) investigational therapy designed to target the CAG repeat expansion that causes all nine known polyglutamine diseases including HD, SCA1 and SCA3.

“We are encouraged by the continued progress of our development program and very pleased to announce the first patient dosed in this Phase 1/2a study of VO659 in HD, SCA1 and SCA3,” said Scott Schobel, MD, chief medical officer at Vico. “VO659 is the first allele-preferential ASO in clinical development with broad application to all CAG repeat expansion diseases. The robust preclinical data package for VO659 demonstrates favorable brain uptake, potency and durability of effect, and we look forward to assessing the translation of these characteristics in this clinical trial.”

VO659’s unique target and dual mechanism of action enable potent target engagement across multiple disease models. In preclinical studies, significant and dose-dependent reductions of mutant huntingtin protein (mHTT) and improvement in motor function were observed in vivo in disease mouse models of HD. Allele-preferential reductions of mHTT were observed in vitro in HD patient cell models. Preclinical data also showed VO659 induced a significant reduction of mutant ATXN1 (mATXN1) and mutant ATXN3 (mATXN3) protein levels in vivo and in vitro in disease mouse models and patient cell models of SCA1 and SCA3, respectively.

The Phase 1/2a clinical trial is a multi-center, open-label basket study designed to assess the safety and tolerability of multiple ascending doses of VO659 administered intrathecally in participants with early manifest HD or mild to moderate SCA1 or SCA3. Exploratory endpoints include the assessment of pharmacodynamic biomarkers (mHTT, total HTT, mATXN3, total ATXN3 and neurofilament light chain) in cerebrospinal fluid, plasma pharmacokinetics, and clinical outcome measures. The study is expected to enroll approximately 71 participants.

“It is our mission to bring safe, effective therapies to patients and families affected by devastating neurological diseases, and today marks an important milestone in our journey to realize this mission. We are grateful to the trial investigators and patients participating in our Phase 1/2a study as we assess the potential of VO659 in HD, SCA1 and SCA3. We also look forward to sharing more details about the study at CHDI’s Annual Huntington’s Disease Therapeutics Conference later this month,” said Micah Mackison, chief executive officer at Vico.

The company also announced that researchers will be highlighting preclinical data of VO659 in an oral presentation along with poster presentations of the Phase 1/2a trial design and additional preclinical data of VO659 at the CHDI Foundation’s 18th Annual Huntington’s Disease Therapeutics Conference being held in Dubrovnik, Croatia from April 24-27, 2023. Details of Vico’s presentations at CHDI’s Annual Conference are as follows:

Oral Presentation

Title: VO659, an allele-preferential CAG repeat-targeting ASO with therapeutic potential for patients with Huntington’s disease and spinocerebellar ataxia types 1 and 3
Presenter: Nicole Datson, PhD, Chief Scientific Officer, Vico
Session: Session III – Novel mechanisms, modalities, and candidates for HD therapeutics
Date and Time: Wednesday, April 26 at 9:00 am CET

Poster Presentations

Title: VO659, a CAG repeat-targeting ASO, blocks translation of polyQ proteins in a CAG repeat length dependent and allele preferential manner
Presenter: Ruurd Verheul, Scientist, Vico
Date and Time: Monday, April 24 – Thursday, April 27

Title: Design of a first-in-human, phase 1/2a trial of VO659, a CAG repeat-targeting ASO in patients with Huntington’s disease and spinocerebellar ataxia types 1 and 3
Presenter: Katja Obieglo, PhD, Clinical Scientist, Vico
Date and Time: Monday, April 24 – Thursday, April 27

About Vico Therapeutics B.V.

Vico Therapeutics is a clinical-stage genetic medicines company developing antisense oligonucleotide (ASO) RNA modulating therapies for patients with severe neurological diseases. Vico’s platform designs ASOs to modulate RNA through multiple approaches including inhibition of translation, modulation of splicing, editing, degradation, and activation. We apply precision chemistry to identify an RNA modulator that achieves the desired target engagement and safety profile for different diseases. Our lead product candidate, VO659, is currently in Phase 1/2a clinical development for the treatment of Huntington’s disease and spinocerebellar ataxia types 1 and 3. For more information, visit

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SOURCE Vico Therapeutics B.V.