A Study to Assess THN391 in Subjects With Alzheimer's Disease

Condition(s) studied

Investigational drug(s) / intervention(s)

THN391: THN391, IV infusion, 3\*Q4W (every 4 weeks)

Placebo: Placebo for comparison with THN391, IV infusion, 3\*Q4W

THN391: THN391, IV infusion, 6\*Q4W (every 4 weeks)

Placebo: Placebo for comparison with THN391, IV infusion, 6\*Q4W

Study summary

This is a Phase 1b study to evaluate different doses of the drug and see whether a drug is safe and how it behaves in the body.

THN391 has already been assessed in healthy people without Alzheimer's disease. This is the first study of THN391 in patients with Early Alzheimer's disease. Later studies will evaluate THN391 to see if it is effective for the treatment of Alzheimer's disease.

In this study, THN391 will be compared with a placebo (a look-alike substance that contains no drug). The study duration depends on the number of dose administrations: for the 3 doses administration, the duration is approx. 8 months, in which the participants will visit the clinic approximately 13 times and have 2 telephone calls with the site. For the 6 doses administration group (starting in Jan 2026), the duration is approx. 11 months, with 19 clinic visits and 5 telephone calls with the site.

Patients who fulfill all criteria to participate in the study, will receive 3 or 6 times a monthly dose of THN391 or placebo in the clinic.

Assessments that will be done at several timepoints during the study will be blood collection, physical examinations and neurological examinations, 5-7x an MRI-scan of the head, 3x a spinal tap and some testing of the memory and thinking skills.

Eligibility

Primary outcome measure(s)

• To assess the safety and tolerability of multiple doses of THN391 in Early AD subjects via AEs — From enrollment to the end of the follow-up period (6 months post dosing)
  Incidence of Adverse Events (AEs)
• To assess the safety and tolerability of multiple doses of THN391 in Early AD subjects via SAEs — From enrollment to the end of the follow-up period (6 months post dosing)
  Incidence of Serious Adverse Events (SAEs)
• To assess the pharmacokinetics (PK) of multiple doses of THN391 in Early AD subjects — From the first dosing to the end of the follow-up period (6 months post dosing)
  Serum and CSF concentration of THN391 using validated analytical method at specified timepoints The PK parameters will be determined or calculated using non-compartmental analysis from the serum concentration time data for THN391. A complete list of PK parameters will be provided in the statistical analysis plan (SAP).
• To assess the maximum plasma concentration (Cmax) for THN391 in Early AD subjects — From the first dosing to the end of the follow-up period (6 months post dosing)
  Evaluate Cmax for serum and CSF concentration of THN391 at specified time points
• To assess area under the curve concentration (AUC) for THN391 in Early AD subjects — From the first dosing to the end of the follow-up period (6 months post dosing)
  Evaluate AUC for serum and CSF concentration of THN391 at specified time points
• To measure the half-life (t1/2) of THN391 in Early AD subjects — From the first dosing to the end of the follow-up period (6 months post dosing)
  Evaluate PK in serum and CSF concentration of THN391 at specified time points

Trial sites (4)