This section highlights FDA-related milestones and regulatory updates for drugs developed by AC Immune (ACIU).
Over the past two years, AC Immune has reported clinical trial outcomes, regulatory submissions, approvals, and other FDA events for drugs and therapies such as
TDP-43, ACI-24, ACI-19764, ACI-7104.056, ACI-35.030, ACI-24.060, and PI-2620. For definitions of regulatory abbreviations such as NDA, BLA, or PDUFA, see the event status legend.
Select a button below to view the list of FDA events for that drug.
TDP-43 FDA Regulatory Timeline and Events
TDP-43 is a drug developed by AC Immune for the following indication: tracers for imaging.
This drug is under review by the U.S. Food and Drug Administration (FDA).
Below is a timeline of key regulatory milestones for this therapy.
- Drug:
- TDP-43
- Announced Date:
- May 22, 2026
- Indication:
- tracers for imaging
Announcement
AC Immune SA announced the presentation of new preliminary data from a Phase 1 trial of its first-in-class TDP-43 positron emission tomography (PET) tracer ACI-19626 showing increased uptake in the brains of patients with amyotrophic lateral sclerosis (ALS).
AI Summary
AC Immune SA announced new preliminary Phase 1 data for ACI-19626, its first-in-class TDP-43 PET tracer. The results showed higher tracer uptake in the brains of patients with amyotrophic lateral sclerosis (ALS), which may help identify TDP-43 pathology in living patients. The company said ACI-19626 continued to show good safety and tolerability, with radiation exposure within accepted limits. It also showed rapid brain uptake and washout, suggesting a pharmacokinetic profile that could work well for human brain imaging.
These findings may support future use of ACI-19626 not only for diagnosis, but also for measuring how well treatments work against TDP-43-related disease. TDP-43 is linked to ALS and other brain disorders, and better biomarkers are badly needed because these diseases can be hard to tell apart early on.
Read Announcement- Drug:
- TDP-43
- Announced Date:
- March 19, 2026
- Indication:
- tracers for imaging
Announcement
AC Immune SA announced the presentation of Phase 1 data including the first in vivo images of TDP-43 pathology in the human brain, detected using its first-in-class positron emission tomography (PET) tracer ACI-19626, at the International Conference on Alzheimer's and Parkinson's Disease (AD/PD™ 2026).
AI Summary
AC Immune SA reported Phase 1 results showing the first in vivo images of TDP-43 brain pathology in humans, captured with its first‑in‑class PET tracer ACI‑19626 and presented at AD/PD 2026. The initial data show the tracer can visualize TDP‑43 in people, marking a major step for imaging this protein in living patients.
Early findings indicate significantly higher tracer uptake in patients with genetically defined frontotemporal dementia (FTD). ACI‑19626 showed good safety and tolerability and a pharmacokinetic profile suitable for human brain imaging in this Phase 1 study.
TDP‑43 is a key protein in FTD, amyotrophic lateral sclerosis (ALS) and LATE, and often appears with Alzheimer’s and Parkinson’s disease. A reliable TDP‑43 PET tracer could help distinguish overlapping conditions and enable a precision medicine approach across multiple neurodegenerative diseases by providing a needed biomarker for diagnosis and research.
Read Announcement- Drug:
- TDP-43
- Announced Date:
- November 19, 2025
- Indication:
- tracers for imaging
Announcement
Prothena Corporation plc announced a scientific presentation at Neuroscience 2025, hosted by the Society for Neuroscience (SfN) in San Diego, CA.
AI Summary
Prothena Corporation announced a scientific presentation at Neuroscience 2025 in San Diego, CA. The poster (PSTR440.04) titled “Treatment with a Cell-Internalizing CYTOPE® Targeting pTDP-43 Reduces Intraneuronal Pathology in a Mouse Model of ALS” will be shown in session PSTR440: ALS and Motor Neuron Disease on November 19, 2025 at 1pm PT.
Preclinical results show their TDP-43 CYTOPE® therapy, given systemically, quickly reached the brain and other tissues, entered cells, and colocalized with pathological pTDP-43. In an ALS mouse model (rNLS8) it significantly reduced intracellular pTDP-43 in motor cortex and neuromuscular junctions. In human-derived neuronal cells and iPSC motor neurons, CYTOPE entered the cytosol, cleared cytosolic pTDP-43 aggregates, and reduced RNA problems caused by cryptic exon inclusion — key features of TDP-43 diseases.
Prothena says CYTOPE is a new delivery method that helps large molecules escape cellular compartments and act inside cells, potentially targeting previously undruggable disease pathways.
Read Announcement- Drug:
- TDP-43
- Announced Date:
- October 24, 2025
- Indication:
- tracers for imaging
Announcement
AC Immune SA announced the publication in Nature Communications of preclinical data on its first-in-class brain positron emission tomography (PET) tracers for imaging TDP-43 pathology.
AI Summary
AC Immune SA announced in Nature Communications the first preclinical data for its innovative brain PET tracer, ACI-19626, designed to image TDP-43 pathology. Aggregated TDP-43 is a hallmark of ALS, frontotemporal degeneration, LATE and is seen alongside Alzheimer’s and Parkinson’s diseases. Reliable PET imaging of TDP-43 could help doctors distinguish these overlapping conditions and improve early diagnosis.
The study showed that ACI-19626 binds specifically to pathological TDP-43 aggregates with no off-target effects, rapidly enters the brain, and clears quickly when no target is present. These strong preclinical results led AC Immune to begin a Phase 1 clinical trial, with initial human data expected in Q4 2025. If successful, this tracer could become a vital tool in precision medicine, guiding treatment decisions and speeding the development of new therapies for TDP-43 proteinopathies. It may also help researchers stratify patients and measure target engagement in trials.
Read Announcement
ACI-24 (anti-Abeta vaccine) FDA Regulatory Events
ACI-24 (anti-Abeta vaccine) is a drug developed by AC Immune for the following indication: Alzheimer's disease in patients with Down syndrome.
This drug is under review by the U.S. Food and Drug Administration (FDA).
Below is a timeline of key regulatory milestones for this therapy.
- Drug:
- ACI-24 (anti-Abeta vaccine)
- Announced Date:
- April 30, 2026
- Indication:
- Alzheimer's disease in patients with Down syndrome
Announcement
AC Immune SA announced it dosed the first patients in Cohort AD4 in the ongoing Phase 1b/2 ABATE trial. As a result, AC Immune will receive a $12 million milestone payment from Takeda under the partners' exclusive, worldwide option and license agreement for AC Immune's active immunotherapies targeting toxic forms of amyloid beta (Abeta), including ACI-24 for the treatment of Alzheimer's disease (AD).
AI Summary
AC Immune SA announced it has dosed the first patients in Cohort AD4 of the ongoing Phase 1b/2 ABATE trial. Treatment of the first AD4 patient triggered a $12 million milestone payment from partner Takeda under their exclusive worldwide option and license agreement. AD4 enrolls people with prodromal Alzheimer’s disease and completes the trial’s planned cohorts.
ABATE is testing ACI-24, an active immunotherapy designed to produce antibodies against toxic forms of amyloid beta that drive plaque formation. The randomized, double‑blind, placebo‑controlled trial is assessing safety, tolerability, immunogenicity and pharmacodynamic effects; earlier cohorts showed ACI-24 was generally well tolerated and induced anti‑Abeta antibody responses. AC Immune runs the ABATE trial; if Takeda exercises its option, Takeda would fund and lead further clinical development, global regulatory work and commercialization under the partners’ agreement.
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ACI-19764 FDA Regulatory Events
ACI-19764 is a drug developed by AC Immune for the following indication: an orally administered small molecule inhibitor of the NLRP3 inflammasome.
This drug is under review by the U.S. Food and Drug Administration (FDA).
Below is a timeline of key regulatory milestones for this therapy.
- Drug:
- ACI-19764
- Announced Date:
- February 24, 2026
- Indication:
- an orally administered small molecule inhibitor of the NLRP3 inflammasome.
Announcement
AC Immune SA announced that the first participant has been dosed in a Phase 1 clinical trial of ACI-19764, an orally administered small molecule inhibitor of the NLRP3 inflammasome.
AI Summary
AC Immune SA announced that the first participant has been dosed in a Phase 1 clinical trial of ACI-19764, an orally administered small-molecule inhibitor of the NLRP3 inflammasome. The company, based in Lausanne, is testing this compound in early-stage human studies to begin assessing safety, tolerability, and initial pharmacology in people. This marks the start of first-in-human evaluation for ACI-19764.
Targeting the NLRP3 inflammasome aims to reduce chronic inflammation thought to drive progression in a range of disorders. AC Immune says the approach could be relevant to inflammatory and metabolic conditions as well as neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis (ALS), and frontotemporal dementia. The Phase 1 trial will generate initial human data that will guide whether and how ACI-19764 advances into later-stage studies.
Read Announcement
ACI-7104.056 FDA Regulatory Events
ACI-7104.056 is a drug developed by AC Immune for the following indication: For Parkinson's Disease.
This drug is under review by the U.S. Food and Drug Administration (FDA).
Below is a timeline of key regulatory milestones for this therapy.
- Drug:
- ACI-7104.056
- Announced Date:
- December 11, 2025
- Indication:
- For Parkinson's Disease
Announcement
AC Immune SA announced positive interim safety and efficacy results from the Phase 2 VacSYn trial of its wholly-owned anti-alpha-synuclein (a-syn) active immunotherapy ACI-7104.056 in early Parkinson's disease (PD).
AI Summary
AC Immune announced positive interim safety and efficacy results from the Phase 2 VacSYn trial of its active immunotherapy ACI-7104.056 in early Parkinson’s disease. Results suggest that targeting alpha‑synuclein (a‑syn) with this vaccine may slow PD progression: total CSF a‑syn levels stabilized in treated patients versus a decline in placebo (post‑hoc p=0.018), CSF neurofilament light (NfL) remained stable versus increases in placebo, and plasma GFAP and DaT SPECT imaging showed trends consistent with disease stabilization. Motor scores (MDS‑UPDRS Part III) also suggested stabilization in the active arm. Part 1 included 34 patients treated for at least 12 months, with 20 treated up to 18 months.
All immunogenicity targets were met with a 100% responder rate; serum and CSF antibody titers were over 500‑fold higher than placebo and antibodies crossed the blood‑brain barrier, with strong serum–CSF correlations (Spearman 0.92 at week 24, 0.85 at week 76). ACI‑7104.056 was generally well tolerated with no drug‑related serious adverse events; common side effects were injection site reactions, headaches and fatigue. AC Immune plans to seek regulatory feedback and advance development, with final Part 1 data expected mid‑2026.
Read Announcement- Drug:
- ACI-7104.056
- Announced Date:
- April 2, 2025
- Indication:
- For Parkinson's Disease
Announcement
AC Immune SA announced additional interim safety and positive immunogenicity data from the Phase 2 VacSYn clinical trial evaluating ACI-7104.056, its wholly owned anti-alpha-synuclein (a-syn) active immunotherapy candidate, for the treatment of patients with early Parkinson's disease (PD).
AI Summary
AC Immune SA announced encouraging interim results from its Phase 2 VacSYn trial for early Parkinson’s disease. The study focused on ACI-7104.056, the company’s wholly owned active immunotherapy candidate targeting pathological alpha-synuclein. Interim data showed that repeated immunizations led to a strong immune response, with anti-alpha-synuclein antibody levels increasing over 20 times higher than those seen in the placebo group after four doses. The trial also confirmed that the treatment is well tolerated, with only mild side effects such as injection site reactions and headaches reported. These findings support the boostability of the immune response and underline the potential of ACI-7104.056 as a best-in-class candidate for treating early Parkinson’s disease. AC Immune looks forward to further updates later in 2025 as the study continues to monitor safety and immunogenicity.
Read Announcement
ACI-35.030 FDA Regulatory Timeline and Events
ACI-35.030 is a drug developed by AC Immune for the following indication: Alzheimer’s Disease (AD).
This drug is under review by the U.S. Food and Drug Administration (FDA).
Below is a timeline of key regulatory milestones for this therapy.
- Drug:
- ACI-35.030
- Announced Date:
- September 25, 2025
- Indication:
- Alzheimer’s Disease (AD)
Announcement
AC Immune SA announced the peer-reviewed publication in eBioMedicine of results from the completed Phase 1b/2a trial of active immunotherapy ACI-35.030's (JNJ-2056) partnered with Janssen Pharmaceuticals, Inc., a Johnson & Johnson company.
Read Announcement- Drug:
- ACI-35.030
- Announced Date:
- September 17, 2024
- Indication:
- Alzheimer’s Disease (AD)
Announcement
AC Immune SA announced that it will receive the second ReTain-related milestone payment (CHF 24.6 million) under its agreement with Janssen Pharmaceuticals, Inc. (Janssen), a Johnson & Johnson company.
AI Summary
AC Immune SA announced that it will receive a second milestone payment of CHF 24.6 million from Janssen Pharmaceuticals, a Johnson & Johnson company. This payment was triggered by the rapid prescreening rate in the Phase 2b ReTain trial of its active-immunotherapy candidate ACI-35.030, now called JNJ-2056. The trial is testing the treatment in people with preclinical Alzheimer’s disease, a key stage where the disease is present but symptoms have not yet developed. With this contribution, milestone payments related to the trial now total CHF 40 million. AC Immune stated that the payment underscores the promise of their technology platforms and drug development capabilities in the fight against neurodegeneration. It also strengthens the company’s financial position, supporting ongoing efforts to reach several critical milestones in the fight against Alzheimer’s disease.
Read Announcement- Drug:
- ACI-35.030
- Announced Date:
- July 25, 2024
- Indication:
- Alzheimer’s Disease (AD)
Announcement
AC Immune SA announced that its active-immunotherapy candidate, ACI-35.030 (now called JNJ-2056), targeting the pathologic form of the Tau protein, phosphorylated Tau (pTau), has received Fast Track designation from the U.S. Food and Drug Administration (FDA).
AI Summary
AC Immune SA’s active immunotherapy candidate, ACI-35.030—now known as JNJ-2056—has received Fast Track designation from the U.S. FDA. This recognition is granted because the treatment specifically targets phosphorylated Tau (pTau), a toxic form of the Tau protein that is strongly linked to Alzheimer’s disease progression.
The Fast Track status could help speed up the development and regulatory review of JNJ-2056, increasing hope that the therapy will effectively delay or reduce the spread of the pathological pTau in Alzheimer’s patients. This move underlines the therapeutic potential of the candidate, which has already demonstrated its ability to target the harmful form of Tau while sparing the normal protein. Alongside this FDA milestone, AC Immune is advancing its strategy to treat early Alzheimer’s, reinforcing the focus on precision medicine for neurodegenerative diseases.
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ACI-24.060 FDA Regulatory Events
ACI-24.060 is a drug developed by AC Immune for the following indication: To assess the safety, tolerability, immunogenicity, and pharmacodynamic effects of ACI-24.060.
This drug is under review by the U.S. Food and Drug Administration (FDA).
Below is a timeline of key regulatory milestones for this therapy.
- Drug:
- ACI-24.060
- Announced Date:
- December 10, 2024
- Indication:
- To assess the safety, tolerability, immunogenicity, and pharmacodynamic effects of ACI-24.060
Announcement
AC Immune SA announced interim safety and tolerability data from the ABATE Phase 1b/2 trial of ACI-24.060 in individuals living with Down syndrome (DS). Targeting toxic forms of amyloid beta (Abeta), ACI-24.060 is an active immunotherapy covering Abeta 1-15 (excluding Abeta T-cell epitopes).
AI Summary
AC Immune SA announced encouraging interim safety and tolerability data from the ABATE Phase 1b/2 trial of ACI-24.060 in individuals with Down syndrome (DS). The trial focused on using this active immunotherapy, which targets toxic forms of amyloid beta by covering Abeta 1-15 while excluding T-cell epitopes. In the first two cohorts treated for up to one year, no serious adverse events related to the study drug were observed, and there were no cases of amyloid-related imaging abnormalities (ARIA).
Based on these promising findings, the company plans to open the high-dose cohort in DS patients. The results suggest that ACI-24.060 may offer a novel therapeutic option for managing brain Abeta pathology in a vulnerable population at risk for Alzheimer’s disease.
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PI-2620 FDA Regulatory Events
PI-2620 is a drug developed by AC Immune for the following indication: For Alzheimer's disease (AD).
This drug is under review by the U.S. Food and Drug Administration (FDA).
Below is a timeline of key regulatory milestones for this therapy.
- Drug:
- PI-2620
- Announced Date:
- August 28, 2024
- Indication:
- For Alzheimer's disease (AD)
Announcement
AC Immune SA announced that its partner Life Molecular Imaging (LMI) has received Fast Track Designation for the Tau positron emission tomography (PET) diagnostic, [18F]PI-2620, from the U.S. Food and Drug Administration (FDA) in three neurodegenerative conditions.
AI Summary
AC Immune SA announced that its partner, Life Molecular Imaging (LMI), has received Fast Track Designation from the U.S. Food and Drug Administration for its Tau positron emission tomography diagnostic, [18F]PI-2620. This designation covers three serious neurodegenerative conditions: Alzheimer’s disease, progressive supranuclear palsy, and corticobasal degeneration. Fast Track status is designed to speed up the development and review process for medical tools that address unmet needs in serious illnesses.
[18F]PI-2620 is a next-generation PET imaging agent currently in Phase 3 trials for Alzheimer’s disease. It works by detecting abnormal Tau protein deposits in the brain, which are a key marker of these conditions. Early and accurate detection may lead to improved treatment outcomes, making this development a significant step forward in the fight against neurodegenerative diseases.
Read Announcement
