A Switch to Doravirine/Islatravir (DOR/ISL) in Participants With Human Immunodeficiency Virus Type 1 (HIV-1) Who Are Virologically Suppressed on Antiretroviral Therapy (ART) (MK-8591A-051)
This study, called MK-8591A-051, is looking into a new HIV-1 treatment called Doravirine/Islatravir (DOR/ISL). It's for people who are already taking antiretroviral therapy (ART) and have their HIV-1 virus well controlled. The main goals are to check if switching to DOR/ISL is safe, doesn't cause too many side effects, and works just as well as continuing their current ART. Researchers want to ensure the new medicine keeps the virus levels very low (undetectable) after 48 weeks, similar to their existing treatment. This is a "Phase 3" study, meaning it's a key step to see if DOR/ISL could become a new option for managing HIV-1.
At a glance
Results
Results from this study
Posted November 2025Results have been published for this study.
What is this study about?
When you have HIV-1, medicines called antiretroviral therapy (ART) are used to keep the virus levels in your body very low. This helps you stay healthy and prevents you from passing the virus on to others. This particular study is for people who are already on ART and whose HIV-1 is well controlled, meaning their viral load is undetectable.
The study wants to see if a newer, combined medicine called Doravirine/Islatravir (DOR/ISL) is a good option for people to switch to. Sometimes, new medicines can offer advantages like fewer pills, fewer side effects, or improved convenience. The researchers will compare people who switch to DOR/ISL with people who continue their current ART. They will carefully monitor both groups to ensure the new medicine is safe and keeps the virus under control.
This is an important step in developing new treatments for HIV-1. By taking part, you could help researchers understand if DOR/ISL can offer another effective and safe treatment choice for people living with HIV-1. It's about finding ways to make managing HIV-1 even better for people in the future.
Key takeaways
- This study is testing a new HIV-1 medicine called Doravirine/Islatravir (DOR/ISL).
- It's for people whose HIV-1 is already well-controlled on their current medication.
- The main goal is to see if DOR/ISL is safe and works as well as existing treatments.
- Participation involves switching to the new medicine or continuing your current one, with regular check-ups over about 12 months.
- You would be helping to find new and potentially better treatment options for HIV-1.
Who may be eligible?
To join this study, you must be at least 18 years old and have HIV-1 infection. Importantly, your HIV-1 must already be well controlled and undetectable on your current HIV medication, and you should have been taking this medication steadily for at least three months without any previous treatment failures.
There are also some reasons why you might not be able to join. For example, if you have HIV-2, certain serious medical conditions like active hepatitis B, or a history of specific cancers, you wouldn't be eligible. You also can't join if you're allergic to any of the study medications, or if you're taking other medicines that might interfere with the study drugs. Women who could become pregnant would need to use effective birth control during the study.
Could this study suit you?
Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.
- Are you 18 years old or older?
- Do you have HIV-1, and is your viral load currently undetectable?
- Have you been on your current HIV medication steadily for at least 3 months, with no past treatment failures?
- Do you not have HIV-2 or active hepatitis B?
- Are you not taking any medications that might interfere with the study drugs?
What does participation involve?
If you decide to participate, you would switch from your current HIV medication to the new combination medicine, Doravirine/Islatravir (DOR/ISL), or continue your current medication, depending on which group you are assigned to. You would take the study medication once a day. You'd have regular visits to the clinic for check-ups, blood tests, and to make sure everything is going well. These visits would happen over about 48 weeks, which is roughly 11-12 months, followed by a final safety check-up. The team will explain exactly what each visit involves and how long it might take.
Potential risks and benefits
Locations (53)
- Kaiser Permanente-Infectious Disease ( Site 3014)Verified postcodeLos Angeles, United States
- Palmtree Clinical Research ( Site 3032)Verified postcodePalm Springs, United States
- Zuckerberg San Francisco General Hospital and Trauma Center-UCSF ID Clinical Trials Center ( Site 30Verified postcodeSan Francisco, United States
- Georgetown University Medical Center ( Site 3006)Verified postcodeWashington D.C., United States
- Midway Immunology and Research Center ( Site 3009)Verified postcodeFt. Pierce, United States
- Orlando Immunology Center ( Site 3004)Verified postcodeOrlando, United States
- CAN Community Health - Sarasota ( Site 3017)Verified postcodeSarasota, United States
- Triple O Research Institute, P.A ( Site 3026)Verified postcodeWest Palm Beach, United States
- Infectious Disease Specialists of Atlanta ( Site 3003)Verified postcodeDecatur, United States
- Chatham County Health Department - Chatham CARE Center-Infectious Disease ( Site 3028)Verified postcodeSavannah, United States
- ID Care ( Site 3041)Verified postcodeHillsborough, United States
- Penn Medicine: University of Pennsylvania Health System-Perelman Center for Advanced Medicine ( SiteVerified postcodePhiladelphia, United States
Common questions
What is HIV-1 RNA?
HIV-1 RNA is a way to measure the amount of HIV-1 virus in your blood. "Undetectable" means the virus level is so low it can't be measured.
What does 'non-inferior' mean in this study?
It means the researchers want to show that the new medicine is at least as good as (not worse than) your current treatment, specifically in keeping your virus undetectable.
What is 'Phase 3'?
Phase 3 is an important stage of testing where a new medicine is given to a larger group of people to confirm its effectiveness, monitor side effects, and compare it to existing treatments.
Will I know if I'm taking the new medicine or my old one?
The study design will determine this. Sometimes participants are told, sometimes they are not (this is called 'blinding') to ensure unbiased results.
What if I get pregnant during the study?
Women who could become pregnant must use effective birth control. If you were to become pregnant, the study team would discuss the best and safest steps for your health and the baby's.
How to find out more
Always speak to your GP or specialist before deciding to take part in a study.
Discussion
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