Name: ALZ-801
Synonyms: NRM-8499, homotaurine, 3-APS
Therapy Type: Small Molecule (timeline)
Target Type: Amyloid-Related (timeline)
Condition(s): Alzheimer's Disease
U.S. FDA Status: Alzheimer's Disease (Phase 3)
Company: Alzheon Inc.


This is a prodrug of homotaurine, a modified amino acid previously developed under the names tramiprosate and Alzhemed™. ALZ-801 is converted to homotaurine in vivo, but is more easily absorbed and lasts longer in the blood than tramiprosate.

Tramiprosate was reported to inhibit Aβ42 aggregation into toxic oligomers (Gervais et al., 2007; Kocis et al., 2017). Both ALZ-801 and tramiprosate are metabolized to 3-sulfopranpanoic acid (3-SPA), which is normally found in brain and also inhibits Aβ42 aggregation (Hey et al., 2018).

After tramiprosate failed in Phase 3, its maker, NeuroChem, marketed it as a nutritional supplement. Years later, a subgroup analysis of the trial data indicated a signal for a potential positive effect in participants who carried two copies of ApoE4 (Abushakra et al., 2016; Abushakra et al., 2017). Alzheon licensed ALZ-801 from NeuroChem and is developing it for Alzheimer’s disease.


Alzheon published results of a Phase 1 study of safety, tolerability, and pharmacokinetics of single and multiple doses of ALZ-801 in 127 healthy, old volunteers (Hey et al., 2018). The prodrug caused mild nausea and vomiting, which were not dose-related and went away after a week on drug or when taking the drug with food. Other common side effects were headaches, dizziness, and falls, also not dose-related. The drug had a longer half-life and less variability in blood levels between people than tramiprosate, and could be taken with food without affecting plasma concentrations. A dose of 265 mg of ALZ-801 twice daily achieved the same blood exposure as the 150 mg dose twice daily used in the Phase 3 tramiprosate trials, and brain levels five to 15 times higher than required to inhibit Aβ42 aggregation in vitro. 

In October 2017, the U.S. Food and Drug Administration granted ALZ-801 Fast Track designation for the treatment of Alzheimer’s disease. According to Alzheon’s website, the company plans to run a Phase 3 trial in people homozygous for ApoE4 with early to mild AD, who will receive 265 mg of ALZ-801 twice a day for 18 months. The primary endpoint will be change in ADAS-COG; secondary endpoints include disability assessment for dementia (DAD), CDR-SB, and MMSE. The trial will also include biomarker endpoints such as hippocampal volume and cortical thickness MRI, as well as CSF and plasma measures of neurofilament light and p-Tau. The company will also reportedly monitor CSF Aβ oligomer concentration (Tolar et al., 2019).

In December 2019, Alzheon announced that its analysis of ADNI and tramiprosate trial data showed differences in cortical thickness between ApoE3/3 and ApoE4/4 carriers with mild AD, and that cortical thickness would be a secondary outcome in the planned Phase 3 trial (company press release). In August 2020, Alzheon announced that the U.S. National Institute on Aging will fund this trial, with plans to begin enrolling 300 participants in early 2021 (press release).

For all ALZ-801 trials, see

Last Updated: 02 Sep 2020


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Therapeutics Citations

  1. Alzhemed™

Paper Citations

  1. . Clinical Pharmacokinetics and Safety of ALZ-801, a Novel Prodrug of Tramiprosate in Development for the Treatment of Alzheimer's Disease. Clin Pharmacokinet. 2018 Mar;57(3):315-333. PubMed.
  2. . The path forward in Alzheimer's disease therapeutics: Reevaluating the amyloid cascade hypothesis. Alzheimers Dement. 2020 Jan 3; PubMed.
  3. . Targeting soluble Abeta peptide with Tramiprosate for the treatment of brain amyloidosis. Neurobiol Aging. 2007 Apr;28(4):537-47. PubMed.
  4. . Elucidating the Aβ42 Anti-Aggregation Mechanism of Action of Tramiprosate in Alzheimer's Disease: Integrating Molecular Analytical Methods, Pharmacokinetic and Clinical Data. CNS Drugs. 2017 Jun;31(6):495-509. PubMed.
  5. . Clinical Benefits of Tramiprosate in Alzheimer's Disease Are Associated with Higher Number of APOE4 Alleles: The "APOE4 Gene-Dose Effect". J Prev Alzheimers Dis. 2016;3(4):219-228. PubMed.
  6. . Clinical Effects of Tramiprosate in APOE4/4 Homozygous Patients with Mild Alzheimer's Disease Suggest Disease Modification Potential. J Prev Alzheimers Dis. 2017;4(3):149-156. PubMed.

External Citations

  1. Alzheon’s website
  2. company press release
  3. press release

Further Reading


  1. . Aducanumab, gantenerumab, BAN2401, and ALZ-801-the first wave of amyloid-targeting drugs for Alzheimer's disease with potential for near term approval. Alzheimers Res Ther. 2020 Aug 12;12(1):95. PubMed.
  2. . The path forward in Alzheimer's disease therapeutics: Reevaluating the amyloid cascade hypothesis. Alzheimers Dement. 2020 Jan 3; PubMed.