Summary: Researchers have reported the successful completion of a Phase 1b clinical trial of a novel immunotherapy for Alzheimer’s disease. The investigational agent, IBC-Ab002, is a humanized anti-PD-L1 monoclonal antibody designed to rejuvenate systemic immune responses rather than directly remove neurotoxic amyloid beta plaques in the brain.
Key Facts
- Established safety profile: The Phase 1b trial demonstrated that IBC-Ab002 was safe and well tolerated at all tested dose levels in patients with early-stage Alzheimer’s disease.
- A non-amyloid therapeutic paradigm: IBC-Ab002 does not act by clearing amyloid plaques directly. Instead, it transiently blocks the PD-1/PD-L1 immune checkpoint to reactivate peripheral immune signaling, promoting clearance of senescent cells and reducing brain inflammation.
- Biomarker improvements: Biological assessments found reductions in biomarkers of active neuronal injury and changes consistent with improved synaptic health following treatment.
- Targeting systemic contributors to brain aging: The therapy addresses age-related immune exhaustion, based on the premise that systemic immune decline drives neuroinflammation and accelerates neurodegeneration.
- International, multicenter trial: The study enrolled 40 participants across 11 clinical sites in the United Kingdom, Israel and the Netherlands.
Source: Weizmann Institute
Multiple research teams worldwide are pursuing ways to prevent, slow or reverse Alzheimer’s disease, which develops in the brain over many years before symptoms appear. While progress has been made, there remains a need for therapies that more effectively change the disease trajectory. This investigational immunotherapy represents an alternative strategy focused on restoring immune function rather than directly targeting amyloid plaques.
Professor Michal Schwartz of the Weizmann Institute’s Brain Sciences Department has led work showing the brain depends on an effective immune system for maintenance and repair. Her research overturned the long-standing idea that the brain is entirely isolated from the immune system or that any immune activity in the brain is necessarily harmful. Schwartz and colleagues demonstrated that age-related immune dysfunction contributes directly to brain inflammation and neurodegeneration, suggesting that targeting immune decline can be a therapeutic strategy for Alzheimer’s disease.
Building on preclinical studies, Schwartz and her team showed in animal models that intermittent relaxation of immune checkpoint inhibition can mobilize peripheral immune responses to reduce brain inflammation, clear dysfunctional cells, and improve cognitive measures. These findings led to the development of an anti-PD-L1 antibody tailored for neurodegenerative disease: IBC-Ab002.
ImmunoBrain, a company co-founded to translate this work, licensed the technology from the Weizmann Institute’s technology transfer office and engineered IBC-Ab002 to have a short-lived systemic action with diminished Fc-mediated effects—properties intended to engage the immune system transiently while limiting prolonged activation. Although it targets the same PD-L1 molecule as some oncology immunotherapies, IBC-Ab002’s design and dosing strategy are optimized for the goal of restoring beneficial immune support to the brain.
A randomized, double-blind Phase 1b clinical trial enrolled 40 participants with early-stage Alzheimer’s disease across five ascending dose cohorts (1–30 mg kg−1) at 11 medical centers in the UK, Israel and the Netherlands. The trial, led clinically by Dr. Tommaso Croese with academic collaboration from Professor Catherine J. Mummery of University College London, evaluated safety and tolerability as the primary endpoints and included exploratory biomarker assessments.
Results indicated IBC-Ab002 was well tolerated at all doses, with no treatment-related serious adverse events and no evidence of amyloid-related imaging abnormalities. Exploratory analyses at week 48 showed dose-directional reductions in cerebrospinal fluid markers of neuronal and synaptic damage, particularly at the highest tested dose, though the small sample size limited statistical power. Overall, the biological activity observed matched the agent’s intended mechanism of transient immune reactivation and supports continued clinical development.
Contributors to the clinical program included investigators from Tel Aviv Sourasky University Medical Center, Tel Aviv University and several ImmunoBrain team members. The research underscores aging immune function as a key modifiable factor in Alzheimer’s disease progression and positions systemic, intermittent immune modulation as a promising therapeutic avenue for further study.
“Aging is the greatest risk factor for Alzheimer’s disease,” says Professor Schwartz. “Our work shows that decline of the immune system fuels chronic brain inflammation, which accelerates disease progression. Restoring the immune system’s youthful capacity to support brain maintenance could slow or even reverse disease-related damage.”
Funding: Prof. Michal Schwartz’s work was supported by the Sagol Institute for Longevity Research, the Thompson Family Foundation Alzheimer’s Disease Research Fund, and the Estate of Daisy Pinchas.
Key Questions Answered:
A: Traditional monoclonal antibodies for Alzheimer’s typically bind amyloid beta in the brain to remove plaques. IBC-Ab002 instead targets the peripheral immune system by briefly blocking PD-L1, restoring immune signaling that helps reduce systemic inflammation and promote clearance of senescent cells that contribute to brain pathology.
A: With age, immune cells become functionally exhausted through inhibitory pathways such as PD-1/PD-L1, impairing the body’s ability to resolve chronic neuroinflammation. Temporarily blocking PD-L1 lifts these inhibitory signals, enabling peripheral immune responses to mitigate inflammation in the central nervous system and support tissue maintenance.
A: In addition to meeting primary safety endpoints, the trial showed target engagement and directional reductions in cerebrospinal fluid biomarkers associated with structural neuronal damage and synaptic loss, especially at the highest dose studied, supporting additional clinical investigation.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The journal paper was reviewed in full.
- Additional context was added by staff.
About this Alzheimer’s disease research news
Author: Gizel Maimon
Source: Weizmann Institute
Contact: Gizel Maimon – Weizmann Institute
Image credit: Neuroscience News
Original Research: Open access. “Immunotherapy with a short-lived anti-PD-L1 antibody in Alzheimer’s disease: a phase 1b, randomized, double-blind trial” by Tommaso Croese, Catherine J. Mummery, Noa Bregman, Dalia Bracha, Kuti Baruch, Alexander Kertser, Sharona Raveh, Eliezer Shochat & Michal Schwartz. DOI: 10.1038/s43856-026-01767-4
Abstract
Immunotherapy with a short-lived anti-PD-L1 antibody in Alzheimer’s disease: a phase 1b, randomized, double-blind trial
Although Alzheimer’s disease begins with amyloid plaque accumulation, disease progression is driven in part by chronic neuroinflammation that the aging brain cannot resolve when systemic immune support is impaired by age-related decline. Preclinical rodent studies demonstrated that transient systemic blockade of PD-L1 reduces neuroinflammation, provides neuroprotection and slows disease progression. Based on this mechanism, IBC-Ab002 was engineered as a short-lived anti-PD-L1 antibody with Fc-effector silencing and reduced FcRn binding.
This first-in-human, randomized, double-blind Phase 1b trial in early Alzheimer’s disease assessed safety and tolerability as primary endpoints. Forty participants were enrolled across five ascending dose cohorts (1–30 mg kg−1) and received four doses at three-month intervals. Treatment was well tolerated, with no treatment-related serious adverse events or amyloid-related imaging abnormalities observed. Exploratory analyses at week 48 revealed directional changes in cerebrospinal fluid biomarkers of neuronal and synaptic injury favoring the 30 mg kg−1 dose, although small cohort sizes limited statistical significance. The safety and tolerability profile supports further clinical development of intermittently administered systemic IBC-Ab002 in early Alzheimer’s disease. ClinicalTrials.gov registration: NCT05551741.