The TAF-MS study

Treatment tested

• Tenofovir alafenamide

  Human immunodeficiency virus type 1 reverse transcriptase inhibitor

Placebo or sham

• Capsule coated tablets

Other measures (3)

Inclusion: - 1. Age ≥ 18 to ≤ 70 years, both male and female patients - 2. Diagnosis of RRMS using revised McDonald criteria of clinically definite MS.1 - 3. Currently treated with natalizumab - 4. Demonstrated shedding of EBV in salvia (Shedding is defined as at least one salvia sample with >5.8 virus copies/µL cut-off) Exclusion: - 1. Known hypersensitivity or other serious adverse reaction to the active agent or other component of the study medication. - 4. History of pancreatitis - 5. Prior or current disorders influencing the patient’s ability to give an informed consent or to comply with treatment and follow-up of the protocol - 6. Current users of medications that could interact with the study medication (listed in paragraph 5.6) - 7. Patients who previously have been treated with hematopoietic stem cell transplantation (HSCT) - 8. WBC < 1.5 x 109 /L if not caused by a reversible effect of documented ongoing medication. If WBC < 1.5 x 109 /L is caused by a reversible effect of documented ongoing medication the WBC count must be > 1,5 x 109 /L before start of study treatment. - 9. Platelet (thrombocyte) count < 100 x 109 /L - Creatinin clearance < 15 ml/min - 10. ALAT more than 2 times the upper normal reference limit (ULN) - 11. Serum creatinine > 200 µmol/L - 12. Serum bilirubin > 2 times the ULN - 13. Any other disease that can influence the patient safety and compliance, or the evaluation of outcome - 14. Currently enrolled in other trials of an investigational drug, or less than 30 days since ending another investigational drug. - 15. Contraindications to undergo MRI such as a history of claustrophobia, inability to lie flat for approximately one hour, or metal implants (metal pins or plates, extensive non-removable dental work, cerebral aneurysm clips, pacemaker) as assessed by a standardized screening form - 2. Women who are pregnant, as verified by a serum pregnancy test at screening and during follow-up, or lactating - 3. Any ongoing infection with HIV, chronic active hepatitis, hepatitis C, or hepatitis B surface antigen positivity

The objective of the study is to determine the safety of TAF as an add-on therapy to natalizumab.