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HIV-1 InfectionPhase 3NCT04776252

Open-label, Follow-up of Doravirine/Islatravir (DOR/ISL 100 mg/0.75mg) for Participants With Human Immunodeficiency Virus-1 (HIV-1) Infection (MK-8591A-033)

A Phase 3 study testing MK-8591A in people with HIV-1 Infection, run by Merck Sharp & Dohme LLC at 93 sites in 16 countries.

Active, not recruiting

Under way, not looking for participants. Everyone needed has enrolled. The study is still running.

Official record
Search all trials

Trial summary

The safety and tolerability of MK-8591A, a 2-drug fixed dose combination (FDC) of doravirine (100mg) and islatravir (0.75mg) [DOR/ISL 100 mg/0.75 mg) will be evaluated in participants with Human Immunodeficiency Virus -1 (HIV-1) who were treated with DOR and ISL in earlier clinical studies. Read more about this study

Who is it for?
Ages 18 years and older
Conditions the study is for
HIV-1 Infection
What is being tested?
MK-8591A
Type of treatment
Pill or oral medicine
Could I receive a placebo?
No, everyone receives an active treatment
How many people
2,000 participants
Where
93 sitesin 16 countries
Study dates
15 Sep 2021to 29 May 2029
Phase
Phase 3
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • Is currently receiving DOR 100 mg/ISL 0.75 mg adult FDC tablet in an MSD-sponsored clinical study and has completed the last treatment visit.
  • Is considered by the investigator to have derived clinical benefit from receiving DOR/ISL and for whom further treatment with DOR/ISL is considered clinically appropriate.
  • Female is not pregnant or breastfeeding, and at least one of the following conditions applies: Is not a woman of childbearing potential (WOCBP); or is a non-pregnant WOCBP who agrees to the following during the intervention period and for at least 6 weeks after the last dose of study intervention: Not be sexually active, or if sexually active, to use an acceptable method of contraception; or is pregnant and continues to receive study intervention (where allowed by local regulations and as appropriate based on available data/local standard-of-care guidelines)

Who cannot join

  • Is taking or is anticipated to require any prohibited therapies.

Trial locations and contacts

93 sites in 16 countries.

93 sites in 16 countries

United States18 sites

  • St Hope Foundation ( Site 0041)

    Bellaire, Texas, 77401

  • Northstar Healthcare ( Site 0003)

    Chicago, Illinois, 60657

  • North Texas Infectious Diseases Consultants, P.A-Research ( Site 0004)

    Dallas, Texas, 75246

  • Texas Center for Infectious Disease Associates-Clinical Research ( Site 0026)

    Fort Worth, Texas, 76104

  • Midway Immunology and Research Center ( Site 0033)

    Ft. Pierce, Florida, 34982

  • ID Care ( Site 0028)

    Hillsborough, New Jersey, 08844

  • The Crofoot Research Center ( Site 0008)

    Houston, Texas, 77098

  • KC CARE Health Center-Clinical Trials ( Site 0012)

    Kansas City, Missouri, 64111

  • Icahn School of Medicine at Mount Sinai-Clinical and Translational Research Center ( Site 0006)

    New York, New York, 10029

  • Orlando Immunology Center ( Site 0017)

    Orlando, Florida, 32803

  • Bliss Healthcare Services-Research ( Site 0030)

    Orlando, Florida, 32806

  • Penn Medicine: University of Pennsylvania Health System-Perelman Center for Advanced Medicine ( Site

    Philadelphia, Pennsylvania, 19104

  • Pueblo Family Physicians ( Site 0010)

    Phoenix, Arizona, 85015

  • One Community Health ( Site 0045)

    Sacramento, California, 95811

  • Chatham County Health Department - Chatham CARE Center-Infectious Disease ( Site 0015)

    Savannah, Georgia, 31401

  • Whitman-Walker Institute ( Site 0039)

    Washington D.C., District of Columbia, 20005

  • Georgetown University Medical Center-Clinical Trials Unit Division of Infectious Diseases ( Site 002

    Washington D.C., District of Columbia, 20007

  • Triple O Research Institute, P.A ( Site 0031)

    West Palm Beach, Florida, 33407

Other trials in United States

France13 sites

  • Hôpital Avicenne ( Site 1502)

    Bobigny, Île-de-France Region, 93000

  • CHU de Bordeaux Hop St ANDRE-Médecine interne et maladies infectieuses ( Site 1512)

    Bordeaux, Gironde, 33075

  • Centre Hospitalier Universitaire Dijon Bourgogne - Hôpital François Mitterrand ( Site 1516)

    Dijon, Bourgogne-Franche-Comté, 21000

  • Hôpital de la Croix Rousse-Service des Maladies infectieuses et tropicales ( Site 1503)

    Lyon, Rhone, 69004

  • Hospital La Colombière ( Site 1518)

    Montpellier, Herault, 34090

  • Centre Hospitalier Universitaire de Nantes - L' Hopital l'hôtel-Dieu ( Site 1517)

    Nantes, Loire-Atlantique, 44093 Cedex 1

  • Centre Hospitalier Universitaire de Nice - Hôpital l'Archet ( Site 1504)

    Nice, Alpes-Maritimes, 06202

  • Hôpital Bichat - Claude-Bernard-infectious diseases ( Site 1523)

    Paris, 75018

  • Hôpital Saint-Louis-Infectious Diseases and tropical diseases ( Site 1511)

    Paris, Île-de-France Region, 75010

  • Pitie Salpetriere University Hospital-Infectious Disease - Tropical Diseases ( Site 1508)

    Paris, Île-de-France Region, 75013

  • CHU Charles Nicolle-Inefectious disease ( Site 1506)

    Rouen, Haute-Normandie, 76031

  • CHU de Toulouse-Infectious Disease-Tropical Diseases ( Site 1505)

    Toulouse, Haute-Garonne, 31400

  • Tourcoing Hospital-Service Universitaire des Maladies Infectieuses et du Voyageur ( Site 1519)

    Tourcoing, Nord, 59200

Other trials in France

Russia8 sites

  • Republican Clinical Hospital for Infectious Diseases A.F. Agafonova ( Site 2303)

    Kazan', Tatarstan, Respublika, 420140

  • Kuzbasskiy Center for the Prevention and Control of AIDS ( Site 2305)

    Kemerovo, Kemerovo Oblast, 650056

  • Krasnoyarsk Regional Center for the Prevention and Control of AIDS ( Site 2304)

    Krasnoyarsk, Krasnoyarsk Krai, 660049

  • Moscow Infectious Diseases Clinical Hospital Number 2 ( Site 2306)

    Moscow, Moscow, 105275

  • Scientific Advisory Clinical Diagnostic Center Central Resea-Federal AIDS Center ( Site 2302)

    Moscow, Moscow, 105275

  • Republican Clinical Infectious Hospital ( Site 2300)

    Saint Petersburg, Leningradskaya Oblast', 196645

  • Saint-Petersburg Center for Prophylactic of AIDS and Infecti-Saint-Petersburg Center for Prophylact

    Saint Petersburg, Sankt-Peterburg, 190020

  • Smolensk Center for prevention and control of AIDS ( Site 2308)

    Smolensk, Smolensk Oblast, 214006

Other trials in Russia

Canada7 sites

  • Sheldon M. Chumir Health Centre-Southern Alberta Clinic ( Site 0106)

    Calgary, Alberta, T2R 0X7

  • Hamilton Health Sciences- Urgent Care Centre-SIS Clinic ( Site 0109)

    Hamilton, Ontario, L8S 1A4

  • Clinique de médecine Urbaine du Quartier Latin ( Site 0110)

    Montreal, Quebec, H2L 4E9

  • Clinique Medicale lActuel ( Site 0108)

    Montreal, Quebec, H2L 4P9

  • Maple Leaf Research ( Site 0105)

    Toronto, Ontario, M5G 1K2

  • Toronto General Hospital ( Site 0104)

    Toronto, Ontario, M5G 2C4

  • Vancouver Infectious Diseases Centre ( Site 0100)

    Vancouver, British Columbia, V6Z 2C7

Other trials in Canada

Spain7 sites

  • Hospital Germans Trias i Pujol-Fundació Lluita contra la Sida ( Site 1901)

    Badalona, Barcelona, 08916

  • HOSPITAL CLÍNIC DE BARCELONA-Infection Day Hospital ( Site 1900)

    Barcelona, Catalonia, 08036

  • Hospital General Universitario de Elche-Infectius Disease ( Site 1908)

    Elche, Alicante, 03202

  • HOSPITAL GENERAL UNIVERSITARIO GREGORIO MARAÑON-Unidad de Enfermedades Infecciosas ( Site 1903)

    Madrid, Madrid, Comunidad de, 28007

  • Hospital Universitario Infanta Leonor ( Site 1906)

    Madrid, 28031

  • Hospital Universitario Fundación Jiménez Díaz-Internal Medicine. Infectious disease ( Site 1902)

    Madrid, 28040

  • Hospital Universitario La Paz-Internal Medicine ( Site 1904)

    Madrid, 28046

Other trials in Spain

South Africa6 sites

  • Josha Research ( Site 2403)

    Bloemfontein, Free State, 9300

  • Desmond Tutu Health Foundation ( Site 2402)

    Cape Town, Western Cape, 7925

  • King Edward VIII Hospital ( Site 2410)

    Durban, KwaZulu-Natal, 4001

  • Wentworth Hospital ( Site 2400)

    Durban, KwaZulu-Natal, 4052

  • Ezintsha ( Site 2404)

    Johannesburg, Gauteng, 2193

  • Mediclinc Muelmed ( Site 2401)

    Pretoria, Gauteng, 0083

Other trials in South Africa

Switzerland6 sites

  • University Hospital Basel-Infectiology ( Site 2002)

    Basel, Canton of Aargau, 4031

  • Inselspital Bern-Inselspital Infektiologie ( Site 2003)

    Bern, 3010

  • Hôpitaux Universitaires de Genève (HUG)-Infectious Disease Department ( Site 2004)

    Geneva, Canton of Geneva, 1211

  • Ospedale Regionale di Lugano, Sede Civico-Servizio Malattie Infettive ( Site 2005)

    Lugano, Canton Ticino, 6903

  • Cantonal Hospital St.Gallen ( Site 2001)

    Sankt Gallen, Canton of St. Gallen, 9007

  • UniversitätsSpital Zürich ( Site 2000)

    Zurich, Canton of Zurich, 8091

Other trials in Switzerland

Japan5 sites

  • National Hospital Organization Nagoya Medical Center ( Site 0903)

    Nagoya, Aichi-ken, 460-0001

  • National Hospital Organization - Osaka National Hospital - Institute For Clinical Research ( Site 09

    Osaka, 540-0006

  • Tokyo Medical University Hospital ( Site 0904)

    Shinjuku-ku, Tokyo, 160-0023

  • Center Hospital of the National Center for Global Health and Medicine ( Site 0901)

    Shinjyuku-ku, Tokyo, 162-8655

  • Tokyo Metropolitan Komagome Hospital ( Site 0906)

    Tokyo, 113-8677

Other trials in Japan

United Kingdom5 sites

  • Southmead Hospital ( Site 2103)

    Bristol, Bristol, City of, BS10 5NB

  • Brighton and Sussex University Hospitals NHS Trust ( Site 2104)

    East Sussex, Brighton And Hove, BN2 5BE

  • Royal Free Hospital ( Site 2102)

    London, England, NW32QG

  • King's College Hospital ( Site 2101)

    London, England, SE5 9RS

  • North Manchester General Hospital ( Site 2105)

    Manchester, M8 5RB

Other trials in United Kingdom

Chile4 sites

  • Biomedica Research Group-Infectology ( Site 0201)

    Santiago, Region M. de Santiago, 7500710

  • Centro de Investigacion Clinicadela Universidad Catolica ( Site 0204)

    Santiago, Region M. de Santiago, 8330034

  • Universidad de Chile - Hospital Clínico Universidad de Chile ( Site 0200)

    Santiago, Region M. de Santiago, 8380420

  • Hospital hernan henriquez aravena de temuco-Unidad de Investigación Clínica ( Site 0202)

    Temuco, Araucania, 4781151

Other trials in Chile

Italy4 sites

  • Ospedale San Raffaele-U.O. Malattie Infettive ( Site 1602)

    Milan, Lombardy, 20127

  • Ospedale Luigi Sacco-UOC Malattie Infettive I ( Site 1600)

    Milan, Milano, 20157

  • Fondazione IRCCS Policlinico San Matteo-Dipartimento di Malattie Infettive: SC Malattie Infettive (

    Pavia, Lombardy, 27100

  • Fondazione Policlinico Universitario Agostino Gemelli-UOC Malattie Infettive ( Site 1606)

    Rome, Lazio, 00168

Other trials in Italy

Poland4 sites

  • WSS im. W Bieganskiego O. Chorob Zakaznych i Hepatologii-F ( Site 1701)

    Ód, Łódź Voivodeship, 90-001

  • Wojewódzki Szpital Zakaźny w Warszawie ( Site 1702)

    Warsaw, Masovian Voivodeship, 01-201

  • Wrocl.Centr.Zdrowia SPZOZ Osr. Prof-Lecz Ch. Zak. i Terapii Uzaleznien ( Site 1703)

    Wroclaw, Lower Silesian Voivodeship, 50-136

  • EMC Instytut Medyczny S. A. Przychodnia przy ul. Lowieckiej we Wroclawiu ( Site 1700)

    Wroclaw, Lower Silesian Voivodeship, 50-220

Other trials in Poland

Australia3 sites

  • Holdsworth House Medical Practice ( Site 0700)

    Darlinghurst, New South Wales, 2010

  • Fiona Stanley Hospital ( Site 0706)

    Murdock, Western Australia, 6150

  • St Vincent's Hospital-IBAC ( Site 0702)

    Sydney, New South Wales, 2010

Other trials in Australia

Colombia1 site

  • Fundacion Valle del Lili- CIC ( Site 0300)

    Cali, Valle del Cauca Department, 760032

Other trials in Colombia

Germany1 site

  • Medizinische Hochschule Hannover-Department of Immunology and Rheumatology ( Site 1661)

    Hanover, Lower Saxony, 30625

Other trials in Germany

New Zealand1 site

  • Christchurch Hospital-Infectious Diseases ( Site 0800)

    Christchurch, Canterbury, 8011

Other trials in New Zealand

About this study

Official title: A Phase 3 Open-label Rollover Clinical Study of Doravirine/Islatravir (DOR/ISL) Once-daily for the Treatment of HIV-1 Infection in Participants Who Previously Received DOR/ISL in a Phase 2 or Phase 3 DOR/ISL Clinical Study

The safety and tolerability of MK-8591A, a 2-drug fixed dose combination (FDC) of doravirine (100mg) and islatravir (0.75mg) [DOR/ISL 100 mg/0.75 mg) will be evaluated in participants with Human Immunodeficiency Virus -1 (HIV-1) who were treated with DOR and ISL in earlier clinical studies.

Read the detailed description

As of Amendment 12, participants will have the option to continue receiving DOR/ISL (100 mg/0.75 mg) until treatment alternatives are identified, or up to Week 288 given that participants are still deriving benefit, based on individual benefit/risk assessment.

Conditions
HIV-1 Infection
Being tested
MK-8591A

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • MK-8591ADrug

    FDC tablet of 100 mg doravirine, 0.75 mg islatravir taken orally, once daily for up to 192 weeks

Study groups in NCT04776252
Study groupRoleWhat they receive
MK-8591AExperimentalFixed dose combination (FDC) tablet of 100 mg doravirine, 0.75 mg islatravir taken orally, once daily for up to 192 weeks.
Receives: Drug: MK-8591A

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Participants with serious adverse events (SAEs)

    Percentage of participants with serious adverse events (SAEs)

    Measured: Up to Week 198

  2. Participants who discontinued due to an adverse event (AE)

    Percentage of participants who discontinued study treatment due to an AE.

    Measured: Up to Week 192

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted1 Mar 2021
  2. Study start15 Sep 2021
  3. Primary completion29 May 2029 (estimated)
  4. Study completion29 May 2029 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 3
Primary purpose
Treatment
Allocation
Not applicable
Intervention model
Single group
Masking
None (open label)
Enrolment
2,000 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT04776252
Sponsor's protocol ID
8591A-033
Other IDs
MK-8591A-033, jRCT2031210528, 2024-512215-53-00, U1111-1304-7926, 2020-001191-14
Status last verified
Dec 2025
First submitted
26 Feb 2021
Last updated
23 Dec 2025
Results posted
No
Data monitoring committee
No
FDA-regulated drug
Yes
FDA-regulated device
No
Individual data sharing
Yes: https://trialstransparency.msdclinicaltrials.com/pdf/ProcedureAccessClinicalTrialData.pdf

Questions about this trial

What is this clinical trial studying?

A Phase 3 study testing MK-8591A in people with HIV-1 Infection, run by Merck Sharp & Dohme LLC at 93 sites in 16 countries.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 3 inclusion and 1 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: under way, not looking for participants, as of the sponsor's last update on 23 Dec 2025. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 93 sites in United States, France, Russia, Canada, Spain and 11 more countries. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Participants with serious adverse events (SAEs) (time frame: Up to Week 198). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT04776252.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 23 Dec 2025.

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