Repurposing a Combination Antiretroviral Drug Therapy to Target Retrotransposons and Treat Early Alzheimer's Disease

The goal of this clinical trial is to determine the safety, tolerability, drug levels and biological effects of two doses of emtricitabine (FTC) and tenofovir disoproxil fumarate (TDF) combination administered daily for 4 weeks in older adults with early Alzheimer's disease. The main questions it aims to answer are:

• Is FTC-TDF combination safe in older adults who have early Alzheimer's disease.
• To measure the FTC-TDF levels at different times.
• To measure the biological effects of FTC-TDF combination.
• To measure the effects of FTC-TDF combination on inflammation.

Researchers will compare two doses of FTC-TDF combination to a placebo (a look-alike substance that contains no drug) to see if FTC-TDF combination is safe in older adults who have early Alzheimer's disease.

Participants will:

• Take FTC-TDF combination or a placebo every day for 28 days.
• Have 10 clinic visits over approximately 3 months.
• Undergo blood tests, physical exams, cognitive testing, and scans of their brain.

Study Overview

• Status: Not yet recruiting
• Conditions: Alzheimer's Disease
• Intervention / Treatment: Drug: Emtricitabine and tenofovir disoproxil fumarate combination; Drug: Placebo

Detailed Description

Objectives:

To conduct a phase 1b trial to determine the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of multiple ascending doses of emtricitabine (FTC) and tenofovir disoproxil fumarate (TDF) combination administered daily for 4 weeks in older adults with early Alzheimer's disease (AD).

Primary:

1) To evaluate safety and tolerability, we will conduct structured monitoring of adverse events (AEs) and serious AEs (SAEs). Additionally, we will perform safety laboratory tests including blood counts and chemistries, coagulation profile, physical exams, vital signs, and electrocardiogram (ECG).

Secondary:

1. To study the PK of two ascending dose regimens of FTC-TDF combination, we will measure the circulating levels of these drugs pre-dose and at 0.5, 1, 2, 4, 8, and 24 hours on Days 0 and 28. Additional single nadir blood samples will be obtained on days 3, 7, and 14 approximately 24 hours following the previous dose. Single and multiple dose PK parameters will be calculated using nonparametric methods on days 0 and 28: Caverage 0-24h, Cmax, Tmax, lambda z, AUClast, AUC24hr, and T1/2.
2. The trial's primary PD endpoint reflecting target engagement will be the steady-state serum concentration of the active metabolites, tenofovir biphosphate (TBP) and emtricitabine triphosphate (ETP), in peripheral blood mononuclear cells (PBMCs) measured pre-dose and at 4 and 8 hours after administration of study drug on days 0 and 28.
3. We will measure the activity of reverse transcriptase for the human active Long Interspersed Nuclear Elements (LINE-1) in PBMCs using reverse transcription coupled with polymerase chain reaction (PCR) for human LINE-1 transposon sequences on days 0 and 28.
4. We will measure hsCRP, IL-6, and TNF alpha as markers of systemic inflammation on days 0, 14, and 28.

Study Design/ Methodology:

This is a phase 1b, single-center, placebo-controlled, multiple ascending dose study of 20 participants with early AD.

The intervention duration is 28 days. Please see the Schedule of Events table.

There will be a single performance site for the clinical trial at the Center for Alzheimer Research and Treatment (CART) at Brigham and Women's Hospital (BWH).

Starting on day 0, the study participants will be randomized to either placebo or active drug (two dose strengths). The participants will take the study drug orally once daily for 28 days.

Questionnaires will be administered at screening (Clinical Dementia Rating [CDR], Mini-Mental State Exam [MMSE], Logical Memory, 15-item Geriatric Depression Scale [GDS], and Columbia-Suicide Severity Rating Scale [C-SSRS]), which will last up to 45 days.

Number of Participants:

A total of 20 participants will be enrolled in this trial. Participants discontinued from study for any reason or lost-to-follow up before completing the study will be replaced.

Investigational Product, Dosage and Mode of Administration:

Product: FTC and TDF combination tablets at two dose strengths that are in clinical use: 133 mg FTC plus 200 mg TDF, and 200 mg FTC plus 300 mg TDF.

Dosing Cohort: Two dosing cohorts of 10 participants each will be studied successively in ascending order. The first cohort of 10 participants will receive either one tablet of FTC (133 mg) and TDF (200 mg) combination once daily (n=7), or one placebo tablet daily (n=3) for 28 consecutive days. The second cohort of 10 participants will receive either one tablet of FTC (200 mg) and TDF (300 mg) combination once daily (n=7) or one placebo tablet once daily (n=3) for 28 consecutive days.

Duration of Treatment:

Participants will take FTC and TDF combination or placebo tablets once daily for 28 days.

Reference Therapy, Dosage and Mode of Administration:

Placebo tablets once daily for 28 days.

Statistical Methods:

Statistical Power and Sample Size Estimation:

By convention, the sample size of 10 participants per dose group (7 active, 3 placebo) is considered sufficient for evaluation of safety, tolerability, PK, and PD. In previous PK studies of FTC and TDF in adults without HIV infection, the changes from baseline in the plasma concentrations of these drugs were large (>2 standard deviation [SD]); the proposed sample size will provide >80% power to detect changes of similar magnitude in this phase 1b trial. All P values will be considered nominal.

Statistical Analyses:

Safety Analysis: Safety assessments will be based on AE reports and the results of vital signs, ECGs, physical examinations, and laboratory tests, with particular attention to gastrointestinal symptoms, transaminases, creatinine and eGFR, glycosuria, hypophosphatemia, amylase, and lipase. All AEs will be coded and summarized by system organ class (SOC), and preferred term using Medical Dictionary for Regulatory Activities (MedDRA), and Common Terminology Criteria for Adverse Events (CTCAE) version 5.0.

Changes in laboratory measures from baseline to final visit will be compared across groups using mixed-model repeated measures regression (MMRM) with treatment, visit, treatment-by-visit interaction and baseline value adjusted for sex. Shift tables will be generated for the ECG changes from baseline to the post dose by dose groups. Relationship between dose level (linear and discrete) and safety data (change from baseline) will be explored by mixed-effects regression model. Estimates and 95% confidence intervals (CIs) extracted from this model will also be provided. Type 1 error will be set at 0.05, no adjustment will be made for multiplicity, and results will be reported as relative risks and corresponding 95% CIs. In addition to the frequency of AEs, the seriousness and nature of AEs will be considered.

PK Analysis: The PK parameters will be calculated from TDF and FTC plasma concentrations and will include maximum and minimum concentration (Cmax, Cmin), time of the maximum concentration (tmax), area under the concentration curve (AUC) over 24 hours (AUC0-24h), average steady-state concentration (Cssave), AUC from the time of dosing to the last measurable concentration (AUC0-tlast), AUC extrapolated to infinity (AUC0-∞) (where estimable), and terminal phase half-life (t1/2). PK modeling will utilize the Phoenix WinNonlin for non-compartmental analysis, widely considered the industry standard and accepted by the FDA. The following conventions will be utilized: 1) for initial time points, concentrations below the lowest limit of quantification (LLOQ) will be treated as "zero", embedded and/or termination concentrations below the LLOQ are not expected in our assay, but, if observed, will be treated as missing.

Standard single and multiple dose PK parameters will be summarized by dose group using descriptive statistics. Geometric means and coefficients of variation will be presented for Cmax, AUC0-24h, AUClast, and AUCinf. Median and ranges will be presented for Tmax. Means and standard deviations will be provided for the other PK parameters. Dose proportionality will be analyzed using linear regression adjusting for baseline values. Cssave will be compared with historical values from healthy control participants receiving the standard FTC-TDF dose where the same assay and procedures were used.

PD Analysis: Only participants with available baseline values and at least one post-dose value for PD parameters will be included in the change from baseline analyses. The changes from baseline over the 28-day treatment period in the PBMC TDF-DP and FTC-TP concentrations, normalized by DNA content, by dose group will be compared using MMRM with treatment, visit, treatment-by-visit interaction adjusted for baseline. An unstructured covariance matrix will be used to account for intra-individual serial correlation of measures. If unstructured covariance structure matrix results in a lack of convergence, a compound symmetry covariance structure will be employed. The same MMRM approach will be used for the analyses of the change in reverse transcriptase activity in the PBMCs.

PD assessments will be summarized using descriptive statistics for each dose and time point. PD effects will be evaluated in relation to the TDF-DP and FTC-TP exposure (Cssave) by participant and/or by group according to dose level. Time course of PD effects will be plotted.

PK/PD Analysis: Relation between dose level and PK parameters will be analyzed using linear regression models. Estimates and 95% CIs extracted from this model will be employed to assess magnitude of the association. In addition to the PD analysis above, a population PK-PD model will be developed to describe the time course and relation of plasma and TDF-DP and FTC-TP concentrations and PD markers.

• Study Type: Interventional
• Enrollment (Estimated): 20
• Phase: Phase 1

Contacts and Locations

• Study Contact: Name: Danielle M Lavey; Phone Number: 617-732-8085; Email: dlavey@bwh.harvard.edu

Study Locations

• United States
  • Massachusetts
    • Boston, Massachusetts, United States, 02115
      • Brigham and Women's Hospital
      • Contact: Danielle M Lavey; Phone Number: 617-732-8085; Email: dlavey@bwh.harvard.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Meets National Institute on Aging-Alzheimer's Association clinical diagnostic criteria for mild cognitive impairment (MCI) or AD dementia.
• Has evidence of AD assessed by plasma p-tau217. Prior cerebrospinal fluid (CSF) or positron emission tomography (PET) amyloid testing (obtained clinically or through previous research) from the past 2 years may be used for eligibility with approval from study investigators.
• Clinical Dementia Rating (CDR) global score of 0.5 or 1.
• Mini-Mental State Exam (MMSE) score of 18 to 30 (inclusive).
• 15-item Geriatric Depression Scale (GDS) score of < 6.
• Impaired memory performance below an education adjusted cut-off score on the Logical Memory II subscale delayed paragraph recall of Wechsler Memory Scale-Revised (WMS-R) (≥16 years: ≤8; 8-15 years: ≤4; 0-7 years: ≤2).
• May take FDA approved medications for the treatment of AD dementia, but if taking such medications, they must be stable for at least 8 weeks before screening (for cholinesterase inhibitors and/or memantine) or 6 months (for lecanemab or donanemab).
• Has adequate visual and auditory acuity to participate in neuropsychological testing and other study outcomes.
• Has availability of a study partner who has regular contact with the participant and knows him/her well.
• Is willing and able to participate in all assessments in English.
• Is capable of providing written informed consent

Exclusion Criteria:

• Neurologic diseases: Neurologic disease other than AD such as Parkinson's disease, vascular dementia, dementia with Lewy bodies, frontotemporal dementia, normal pressure hydrocephalus, corticobasal syndrome, malignant brain tumor (within the last 1 year), multiple sclerosis, or significant head trauma (e.g. with loss of consciousness for 30 minutes or more) followed by persistent neurologic deficits, or significant structural brain abnormalities.
• Neuroimaging: Magnetic resonance imaging (MRI) scan evidence of cortical stroke or macrohemorrhage (>1 cm), strategically located lacunar stroke, or severe small vessel disease.
• Alcohol or substance use disorder or dependence (Diagnostic and Statistical Manual of Mental Disorders version 5 [DSM 5] criteria) within the last 2 years.
• Untreated major depressive disorder (within the last 1 year), bipolar disorder, schizophrenia (DSM 5 criteria), or current major psychotic symptoms or behavioral problems.
• Any systemic illness or unstable medical conditions, which could affect valid cognitive and self-report assessments.
• Excluded medications: Antipsychotic medications; antidepressant medications with anticholinergic side effects. Washout from psychoactive medications for at least 8 weeks before screening.
• Laboratory abnormalities: AST or ALT > 3 times the upper limit of normal; creatinine clearance <60 mL/min; HbA1C > 8.5%.
• Participation in an investigational trial within the past 3 months or 5 half-lives, whichever is shorter
• Conditions which, in the opinion of the investigator, would jeopardize safety or impact the validity of the study results.
• Person who is positive for HBV Surface Antigen.
• Person with a history of osteoporosis or osteomalacia.
• Person taking FTC-TDF for pre-exposure prophylaxis or treatment of HIV.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: FTC and TDF combination tablet; FTC and TDF combination tablets at two dose strengths that are in clinical use: 133 mg FTC plus 200 mg TDF, and 200 mg FTC plus 300 mg TDF. There is a 70% chance participants will receive the FTC-TDF combination.	Drug: Emtricitabine and tenofovir disoproxil fumarate combination; FTC and TDF combination tablets at two dose strengths that are in clinical use: 133 mg FTC plus 200 mg TDF, and 200 mg FTC plus 300 mg TDF.
Placebo Comparator: Placebo; Placebo tablets. There is a 30% chance participants will receive placebo.	Drug: Placebo; Placebo tablets.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Safety and tolerability	Treatment-emergent adverse events (AEs).	28 days
Safety and tolerability	Treatment-emergent serious AEs (SAEs)	28 days
Safety and tolerability	Changes in clinical laboratory tests. Specifically, will report the number of participants with abnormal laboratory values and/or AEs that are related to treatment.	28 days
Safety and tolerability	Changes in blood pressure (systolic and diastolic)	28 days
Safety and tolerability	Changes in physical exams. Specifically, this will reflect new or worsening findings on a general physical exam and a neurological exam performed by a study physician.	28 days
Safety and tolerability	Clinical findings of 12-lead electrocardiograms (ECGs). Specifically, change in QTc interval.	28 days
Safety and tolerability	Changes in pulse	28 days

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Pharmacokinetics (PK) Concentration average	PK of two ascending dose regimens of FTC-TDF combination: circulating drug levels pre-dose and at 0.5, 1, 2, 4, 8, and 24 hours on Days 0 and 28; single nadir blood samples on days 3, 7, and 14 approximately 24 hours following the previous dose; single and multiple dose PK parameters calculated using nonparametric methods on days 0 and 28 (Concentration average 0-24 hours)	28 days
Pharmacodynamics (PD)	PD endpoint: steady-state serum concentration of active metabolites (TBP and ETP) in PBMCs pre-dose and at 4 and 8 hours after administration of study drug on days 0 and 28.	28 days
Activity of reverse transcriptase	LINE-1 in PBMCs on days 0 and 28.	28 days
Markers of systemic inflammation	hsCRP, IL-6, and TNF alpha on days 0, 14, and 28.	28 days
Pharmacokinetics (PK) Concentration maximum	PK of two ascending dose regimens of FTC-TDF combination: circulating drug levels pre-dose and at 0.5, 1, 2, 4, 8, and 24 hours on Days 0 and 28; single nadir blood samples on days 3, 7, and 14 approximately 24 hours following the previous dose; single and multiple dose PK parameters calculated using nonparametric methods on days 0 and 28 (Concentration maximum).	28 days
Pharmacokinetics (PK) T max	PK of two ascending dose regimens of FTC-TDF combination: circulating drug levels pre-dose and at 0.5, 1, 2, 4, 8, and 24 hours on Days 0 and 28; single nadir blood samples on days 3, 7, and 14 approximately 24 hours following the previous dose; single and multiple dose PK parameters calculated using nonparametric methods on days 0 and 28 (Time to reach maximum concentration [Tmax]).	28 days
Pharmacokinetics (PK) lambda z	PK of two ascending dose regimens of FTC-TDF combination: circulating drug levels pre-dose and at 0.5, 1, 2, 4, 8, and 24 hours on Days 0 and 28; single nadir blood samples on days 3, 7, and 14 approximately 24 hours following the previous dose; single and multiple dose PK parameters calculated using nonparametric methods on days 0 and 28 (apparent terminal elimination rate constant [lambda z])	28 days
Pharmacokinetics (PK) AUC last	PK of two ascending dose regimens of FTC-TDF combination: circulating drug levels pre-dose and at 0.5, 1, 2, 4, 8, and 24 hours on Days 0 and 28; single nadir blood samples on days 3, 7, and 14 approximately 24 hours following the previous dose; single and multiple dose PK parameters calculated using nonparametric methods on days 0 and 28 (Area Under the Curve to the last quantifiable time-point [AUC last]).	28 days
Pharmacokinetics (PK) AUC 24 hours	PK of two ascending dose regimens of FTC-TDF combination: circulating drug levels pre-dose and at 0.5, 1, 2, 4, 8, and 24 hours on Days 0 and 28; single nadir blood samples on days 3, 7, and 14 approximately 24 hours following the previous dose; single and multiple dose PK parameters calculated using nonparametric methods on days 0 and 28 (Area Under the Curve for 24 hours [AUC 24hr]).	28 days
Pharmacokinetics (PK) T 1/2	PK of two ascending dose regimens of FTC-TDF combination: circulating drug levels pre-dose and at 0.5, 1, 2, 4, 8, and 24 hours on Days 0 and 28; single nadir blood samples on days 3, 7, and 14 approximately 24 hours following the previous dose; single and multiple dose PK parameters calculated using nonparametric methods on days 0 and 28 (half-life [T 1/2]).	28 days

Collaborators and Investigators

• Sponsor: Brigham and Women's Hospital
• Investigators: Principal Investigator: Gad A Marshall, MD, Brigham and Women's Hospital

Publications and helpful links

General Publications

• Sullivan AC, Zuniga G, Ramirez P, Fernandez R, Wang CP, Li J, Davila L, Pelton K, Gomez S, Sohn C, Gonzalez E, Lopez-Cruzan M, Gonzalez DA, Parker A, Zilli E, de Erausquin GA, Seshadri S, Espinoza S, Musi N, Frost B. A Phase IIa clinical trial to evaluate the effects of anti-retroviral therapy in Alzheimer's disease (ART-AD). NPJ Dement. 2025;1(1):2. doi: 10.1038/s44400-024-00001-z. Epub 2025 Mar 12.
• Wahl D, Smith ME, McEntee CM, Cavalier AN, Osburn SC, Burke SD, Grant RA, Nerguizian D, Lark DS, Link CD, LaRocca TJ. The reverse transcriptase inhibitor 3TC protects against age-related cognitive dysfunction. Aging Cell. 2023 May;22(5):e13798. doi: 10.1111/acel.13798. Epub 2023 Mar 22.
• Wahl D, Grant RA, LaRocca TJ. The reverse transcriptase inhibitor 3TC modulates hippocampal transcriptome signatures of inflammation in tauopathy model mice. Exp Gerontol. 2024 Jul;192:112458. doi: 10.1016/j.exger.2024.112458. Epub 2024 May 21.
• Valles-Saiz L, Avila J, Hernandez F. Lamivudine (3TC), a Nucleoside Reverse Transcriptase Inhibitor, Prevents the Neuropathological Alterations Present in Mutant Tau Transgenic Mice. Int J Mol Sci. 2023 Jul 6;24(13):11144. doi: 10.3390/ijms241311144.
• Frost B, Dubnau J. The Role of Retrotransposons and Endogenous Retroviruses in Age-Dependent Neurodegenerative Disorders. Annu Rev Neurosci. 2024 Aug;47(1):123-143. doi: 10.1146/annurev-neuro-082823-020615. Epub 2024 Jul 1.
• Singh S, Borkar MR, Bhatt LK. Transposable Elements: Emerging Therapeutic Targets in Neurodegenerative Diseases. Neurotox Res. 2024 Jan 25;42(1):9. doi: 10.1007/s12640-024-00688-1.
• Roy N, Haq I, Ngo JC, Bennett DA, Teich AF, De Jager PL, Olah M, Sher F. Elevated expression of the retrotransposon LINE-1 drives Alzheimer's disease-associated microglial dysfunction. Acta Neuropathol. 2024 Nov 27;148(1):75. doi: 10.1007/s00401-024-02835-6.
• Mustafin RN, Khusnutdinova EK. Involvement of transposable elements in Alzheimer's disease pathogenesis. Vavilovskii Zhurnal Genet Selektsii. 2024 Apr;28(2):228-238. doi: 10.18699/vjgb-24-27.
• Evering TH, Marston JL, Gan L, Nixon DF. Transposable elements and Alzheimer's disease pathogenesis. Trends Neurosci. 2023 Mar;46(3):170-172. doi: 10.1016/j.tins.2022.12.003. Epub 2022 Dec 30.
• Yushkova E, Moskalev A. Transposable elements and their role in aging. Ageing Res Rev. 2023 Apr;86:101881. doi: 10.1016/j.arr.2023.101881. Epub 2023 Feb 10.

Study record dates

Study Major Dates

• Study Start (Estimated): December 1, 2026
• Primary Completion (Estimated): July 1, 2028
• Study Completion (Estimated): September 1, 2028

Study Registration Dates

• First Submitted: August 24, 2026
• First Submitted That Met QC Criteria: August 27, 2026
• First Posted (Actual): August 31, 2026

Study Record Updates

• Last Update Posted (Actual): August 31, 2026
• Last Update Submitted That Met QC Criteria: August 27, 2026
• Last Verified: August 1, 2026

More Information

Terms related to this study

• Keywords: Emtricitabine; Tenofovir disoproxil fumarate; Antiretroviral drug therapy; Retrotransposon
• Additional Relevant MeSH Terms: Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Mental Disorders; Neurocognitive Disorders; Dementia; Tauopathies; Neurodegenerative Diseases; Alzheimer Disease; Heterocyclic Compounds, 1-Ring; Heterocyclic Compounds; Nucleic Acids, Nucleotides, and Nucleosides; Deoxycytidine; Cytidine; Pyrimidine Nucleosides; Pyrimidines; Nucleosides; Deoxyribonucleosides; Emtricitabine
• Other Study ID Numbers: 2026P002048; UG3AG104643 (Other Identifier: NIH, award pending)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: All de-identified data will be made available for sharing with other non-profit entities for non-commercial, legitimate scientific reasons upon appropriate request.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: Yes