graph TD
A["APP"] --> B["alpha-Secretase Cleavage"]
B --> C["sAPPalpha (Neuroprotective)"]
A --> D["BACE1 beta-Secretase Cleavage"]
D --> E["sAPPbeta + C99 Fragment"]
E --> F["gamma-Secretase Cleavage"]
F --> G["Abeta40 (Less Toxic)"]
F --> H["Abeta42 (Aggregation-Prone)"]
H --> I["Oligomer Formation"]
I --> J["Synaptic Toxicity"]
I --> K["Amyloid Plaque"]
J --> L["Cognitive Decline"]
K --> M["Microglial Activation"]
M --> N["Neuroinflammation"]
N --> L
O["BACE1 Inhibitors"] --> P["Reduced Abeta Production"]
style D fill:#ef5350,color:#e0e0e0
style H fill:#ef5350,color:#e0e0e0
style C fill:#1b5e20,color:#e0e0e0
style O fill:#006494,color:#e0e0e0
BACE1 (Beta-Site [Amyloid Precursor Protein](/entities/app-protein) Cleaving Enzyme 1), also known as [beta-secretase](/entities/bace1), is a crucial enzyme in the production of [amyloid-beta](/proteins/amyloid-beta) (Aβ) peptides that accumulate in the brains of Alzheimer's disease patients. BACE1 inhibitors represent one of the most intensively pursued therapeutic strategies for Alzheimer's disease prevention and treatment, targeting the upstream amyloid cascade.
Mechanism of Action
BACE1 is an aspartyl protease that catalyzes the first and rate-limiting step in the amyloidogenic processing of amyloid precursor protein (APP). The enzymatic cleavage produces sAPPβ and C99, which is subsequently cleaved by [gamma-secretase](/entities/gamma-secretase) to release amyloid-beta peptides (Aβ40 and Aβ42).
The BACE1 reaction is the initial and rate-limiting step in amyloid-beta generation, making it an attractive therapeutic target for reducing amyloid-beta production.
Clinical Development
Failed Trials
Several BACE1 inhibitors have progressed to late-stage clinical trials but failed due to safety concerns or lack of efficacy:
Ongoing Trials
Some BACE1 inhibitors continue to be investigated:
Blarcamesine (ANAVEX2-73): Sigma-1 receptor agonist with BACE1 modulation properties