LAUSANNE, Switzerland, August 20, 2026
AC Immune SA announced positive preliminary Phase 1 clinical data for ACI-19764, its wholly owned, orally available small-molecule inhibitor targeting the NLRP3 inflammasome. The first-in-human study showed that ACI-19764 was safe and well tolerated across single- and multiple-ascending-dose cohorts, with no serious adverse events or treatment withdrawals reported to date. Importantly, the investigational therapy demonstrated confirmed brain penetration through cerebrospinal fluid (CSF) exposure), supporting its potential development for neurological and neuroinflammatory conditions. Pharmacokinetic findings indicate that therapeutic exposure may be achievable at doses of 10 mg or less once daily, while the company continues to evaluate the candidate’s pharmacodynamic activity.
AC Immune Confirms Brain Penetration and Dose Potential
Preliminary results from the Phase 1 study in healthy volunteers showed a serum half-life of more than 30 hours, with ACI-19764 evaluated at doses of up to 20 mg per day in the single-ascending-dose cohorts. The study also demonstrated dose-dependent inhibition of IL-1β release in blinded whole-blood assay analysis, providing early evidence that the compound is engaging its intended inflammatory pathway. According to AC Immune, daily doses of ≤10 mg achieved pharmacokinetic concentrations above the IC90, supporting the company’s expectation that a therapeutic dose could potentially be at or below this level. The observed CSF exposure is particularly important for the program because NLRP3-driven inflammation is being investigated as a potential contributor to several central nervous system diseases.
AC Immune Starts Phase 1b Cardiovascular Risk Cohort
The company has now expanded the study into a Phase 1b cardiovascular risk cohort to rapidly assess the anti-inflammatory activity of ACI-19764. Participants are being selected based on elevated high-sensitivity C-reactive protein (hsCRP) levels together with either type 2 diabetes and/or obesity. The cohort is designed to provide an early clinical assessment of whether NLRP3 inhibition can reduce a measurable inflammatory biomarker in people with cardiovascular risk factors. Initial results are expected before the end of 2026, making this the next major clinical milestone for ACI-19764. Full results from the ongoing Phase 1/1b study are expected in the first half of 2027, providing additional information on safety, pharmacokinetics and pharmacodynamic activity.
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ACI-19764 Targets Inflammation Across Neurological Diseases
ACI-19764 is an orally available, brain-penetrant NLRP3 inhibitor designed to selectively target the intracellular NLRP3 inflammasome and reduce production of downstream pro-inflammatory factors, including IL-1β. AC Immune is developing the candidate with potential applications across neurodegenerative, inflammatory and metabolic diseases, reflecting the broad biological role of chronic inflammation. Preclinical studies showed inhibition of neuroinflammation through reduced activation of Iba1-positive microglial cells and GFAP-positive astrocytes in experimental models. The company is positioning ACI-19764 as a wholly owned clinical-stage program within its broader neuroscience pipeline, alongside its α-synuclein-targeting immunotherapy ACI-7104. The emerging Phase 1 data now provide the first human evidence supporting further clinical evaluation of the NLRP3 therapeutic approach, with biomarker data from the cardiovascular-risk cohort expected to help determine the program’s next development steps
Source: AC Immune,, press relese
