The Generative Brain
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Ionis Pharmaceuticals

US antisense company (Carlsbad, California) that develops ION717, the first PrP-lowering drug tested in people, in the PrProfile trial. Its neurology franchise is led by Holly Kordasiewicz, who became chief development officer in 2026. Ionis alone sponsors and controls the program, with the Broad team as scientific collaborators since 2014.

Key facts

  • Vallabh and Minikel connected with Ionis in 2014; in December 2024 Ionis announced the early clinical trial of ION717 was fully enrolled; ASO candidates screened for PRNP mRNA cleavage by RNase H.
  • Evaluates CSF PrP as a pharmacodynamic biomarker using 253 human CSF samples; survival benefit dose-responsive and across all strains tested; discloses that Vallabh consults for Alnylam and has research support from Ionis, and that Kordasiewicz is an Ionis employee.
  • Ionis reports a neurology franchise with three approved medicines and a pipeline of investigational disease-modifying treatments; ION717 was added to the pipeline and PrProfile started in December 2023.
  • Ionis describes ION717 as an antisense medicine designed to inhibit production of prion protein for prion disease and says there are no effective disease-modifying treatments, with most people dying within a year of symptoms.
  • The company neurology pipeline page lists prion disease (PRNP) alongside Alexander disease, Alzheimer disease, Parkinson disease and Huntington disease programs.
  • PrProfile (Phase 1/2a) enrolled 56 symptomatic patients in 2024, has three regimens and a 142-week open-label extension, and reopened with regimen 3 in March 2026; the registry estimates primary completion in February 2027.
  • The NPDPSC treatment-trials page states the trial has reopened for US enrolment, while the registry still shows active, not recruiting, so the two sources lag each other.
  • Pre-symptomatic people at risk are not eligible for PrProfile; the company is developing ION717 itself and said data will be shared at future medical meetings.
  • Ionis expects to report data after primary completion; no timeline for a pre-symptomatic study has been announced in the sources read.

Timeline

  1. 2014First contact with the Vallabh and Minikel team.
  2. 2023PrProfile begins.
  3. 2024PrProfile announced fully enrolled.
  4. 2026Holly Kordasiewicz scheduled to become chief development officer.
  5. 2026Ionis announces regimen 3 and reopens PrProfile.
  6. 2027Estimated primary completion of PrProfile.
Sources for this page