Drugs / Islatravir
Islatravir
also known as
ISL · Islatravir anhydrous · ISLATRAVIR HYDRATE · Islatravir monohydrate · MK-8591 · MK-8591 MONOHYDRATE
Regulatory milestones approvals, filings & regulatory actions · 3 recorded
| Milestone | Jurisdiction | Brand | Indication | Date | Sentence it was read from |
|---|---|---|---|---|---|
| Filed HIV infectious disease 1 milestone | |||||
| Filed | US (FDA) | — | HIV infectious disease | 2025-07-10 | “today announced that the U.S. Food and Drug Administration (FDA) has accepted for review the New Drug Application (NDA) for doravirine/islatravir” merck.com ↗ |
| Approved Indication not stated 2 milestones | |||||
| Approved | US (FDA) | IDVYNSO | — | 2026-04-20 | fda.gov ↗ |
| Clinical hold | US (FDA) | — | HIV-1 pre-exposure prophylaxis | 2021-12-13 | “FDA has placed clinical holds on the investigational new drug applications (INDs) for the oral and implant formulations of islatravir” merck.com ↗ |
Trials 29
| Phase | Registry id | Dates | Indication | Sponsor | Status | Outcome |
|---|---|---|---|---|---|---|
| Phase 18 trials · 1 met primary | ||||||
| Phase 1 | NCT07086079 | Sep → Dec 2025 | — | Merck Sharp & Dohme LLC | Completed | No outcome recorded |
| Phase 1 | NCT06811246 | Feb → Jul 2024 | — | Merck Sharp & Dohme LLC | Completed | No outcome recorded |
| Phase 1 | NCT06719570 | Jan → Mar 2024 | — | Merck Sharp & Dohme LLC | Completed | No outcome recorded |
| Phase 1 | NCT06619678 | Jan → Jun 2024 | — | Merck Sharp & Dohme LLC | Completed | No outcome recorded |
| Phase 1 | NCT04515641 | Nov 2020 → Sep 2021 | HIV infectious disease | Merck Sharp & Dohme LLC | Completed | No outcome recorded |
| Phase 1 | NCT04568603 | Oct 2020 → Jul 2021 | HIV infectious disease | Merck Sharp & Dohme LLC | Completed | No outcome recorded |
| Phase 1 | NCT04303156 | Jun → Oct 2020 | HIV infectious disease | Merck Sharp & Dohme LLC | Completed | No outcome recorded |
| Phase 1 | NCT02217904 | Sep 2015 → May 2017 | — | Merck Sharp & Dohme LLC | Completed | Met primary |
| Phase 29 trials | ||||||
| Phase 2 | NCT07862569 | Dec 2026 → Sep 2029 expected | HIV infectious disease | Merck Sharp & Dohme LLC | Not yet recruiting | No outcome recorded |
| Phase 2 | NCT06891066 | Apr 2025 → Aug 2027 expected | HIV infectious disease | Merck Sharp & Dohme LLC | Active not recruiting | No outcome recorded |
| Phase 2 | NCT05115838 | Jan 2024 → Oct 2025 | HIV infectious disease | Merck Sharp & Dohme LLC | Withdrawn | No outcome recorded Stop: Business |
| Phase 2 | NCT05130086 | Oct 2022 → Mar 2024 | HIV infectious disease | Merck Sharp & Dohme LLC | Withdrawn | No outcome recorded Stop: Business |
| Phase 2 | NCT05052996 | Oct 2021 → Dec 2023 overdue | HIV infectious disease | Gilead Sciences | Active not recruiting | No outcome recorded |
| Phase 2 | NCT04564547 | Mar 2021 → Jan 2025 | HIV infectious disease | Merck Sharp & Dohme LLC | Completed | No outcome recorded |
| Phase 2 | NCT04295772 | Nov 2020 → Dec 2021 | HIV infectious disease | Merck Sharp & Dohme LLC | Completed | No outcome recorded |
| Phase 2 | NCT04003103 | Sep 2019 → Mar 2022 | HIV infectious disease | Merck Sharp & Dohme LLC | Completed | No outcome recorded |
| Phase 2 | NCT03272347 | Nov 2017 → Mar 2021 | HIV infectious disease | Merck Sharp & Dohme LLC | Completed | No outcome recorded |
| Phase 2/31 trial | ||||||
| Phase 2/3 | NCT07266831 | Dec 2025 → Feb 2029 expected | HIV infectious disease | Merck Sharp & Dohme LLC | Recruiting | No outcome recorded |
| Phase 311 trials · 7 met primary | ||||||
| Phase 3 | NCT06630286 | Oct 2024 → Apr 2026 overdue | HIV infectious disease | Gilead Sciences | Active not recruiting | Met primary |
| Phase 3 | NCT06630299 | Oct 2024 → Apr 2026 overdue | HIV infectious disease | Gilead Sciences | Active not recruiting | Met primary |
| Phase 3 | NCT05766501 | Mar 2023 → Oct 2025 overdue | HIV infectious disease | Merck Sharp & Dohme LLC | Active not recruiting | No outcome recorded |
| Phase 3 | NCT05705349 | Mar 2023 → Oct 2025 overdue | HIV infectious disease | Merck Sharp & Dohme LLC | Active not recruiting | Met primary |
| Phase 3 | NCT05631093 | Feb 2023 → Oct 2024 overdue | HIV infectious disease | Merck Sharp & Dohme LLC | Active not recruiting | Met primary |
| Phase 3 | NCT05630755 | Feb 2023 → Oct 2024 overdue | HIV infectious disease | Merck Sharp & Dohme LLC | Active not recruiting | Met primary |
| Phase 3 | NCT04776252 | Sep 2021 → May 2029 expected | HIV infectious disease | Merck Sharp & Dohme LLC | Active not recruiting | No outcome recorded |
| Phase 3 | NCT04652700 | Mar 2021 → Aug 2023 | — | Merck Sharp & Dohme LLC | Terminated | No outcome recorded |
| Phase 3 | NCT04644029 | Feb 2021 → Jul 2023 | HIV infectious disease | Merck Sharp & Dohme LLC | Terminated | No outcome recorded |
| Phase 3 | NCT04223791 | Feb 2020 → Aug 2021 | HIV infectious disease | Merck Sharp & Dohme LLC | Completed | Met primary |
| Phase 3 | NCT04223778 | Feb 2020 → Sep 2021 | HIV infectious disease | Merck Sharp & Dohme LLC | Completed | Met primary |
News releases announcing trial results or a regulatory action · 28
| Date | Issuer | Release |
|---|---|---|
| 2026-08-05 | MSD R&D (China) Co., Ltd. | Results 週1回経口投与のHIV治療薬として開発中のイスラトラビル／レナカパビル配合剤、抗レトロウイルス療法から切り替えた成人HIV陽性者においてウイルス学的抑制を維持 msd.co.jp ↗
主要評価項目である48週時点の結果では、週1回経口投与のHIV治療薬として開発中のイスラトラビル2 mg／レナカパビル300 mg（ISL/LEN）配合錠は、世界の主要なガイドラインで推奨されるBIKTARVY®（ビクテグラビル50 mg／エムトリシタビン200 mg／テノホビルアラフェナミド25 mg配合錠、B/F/TAF）（ISLEND-1試験）またはその他の標準治療で毎日経口投与する抗レトロウイルス療法（ISLEND-2試験）から切り替えたウイルス学的抑制が得られている成人HIV陽性者において、有効性が示されました。 |
| 2026-08-04 | Merck Sharp & Dohme LLC | Results Merck & Co., Inc., Rahway, N.J., USA Announces Second-Quarter 2026 Financial Results; Highlights Key Regulatory and Clinical Milestones Across Broad, Diverse Pipeline merck.com ↗
In collaboration with Gilead, presented first Phase 3 results for islatravir/lenacapavir (ISL/LEN), an investigational oral once-weekly single-tablet HIV treatment regimen, which maintained virological suppression in adults with HIV who switched antiretroviral therapy. |
| 2026-05-15 | MSD R&D (China) Co., Ltd. | Regulatory FDA、1日1回投与のIDVYNSO™（ドラビリン／イスラトラビル）を承認 msd.co.jp ↗
FDA、1日1回投与のIDVYNSO™（ドラビリン／イスラトラビル）を承認 |
| 2026-04-21 | Merck Sharp & Dohme LLC | Regulatory FDA Approves Merck’s Once-Daily IDVYNSO™ (doravirine/islatravir) merck.com ↗
IDVYNSO is approved for adults with virologically suppressed HIV-1 with no history of virologic treatment failure and no known substitutions associated with resistance to doravirine |
| 2026-03-13 | MSD R&D (China) Co., Ltd. | Results Merck & Co., Inc., Rahway, NJ, USA、HIV-1感染症成人患者を対象とした1日1回投与のドラビリン／イスラトラビル（DOR/ISL）の2剤配合錠について、第3相試験の最新のデータ３件をCROI 2026で発表 msd.co.jp ↗
Merck & Co., Inc., Rahway, NJ, USA（米国とカナダ以外ではMSD）は本日、開発中の1日1回経口投与のドラビリン／イスラトラビル［DOR/ISL（100 mg/0.25 mg）、（MK-8591A）］2剤配合錠について、HIV-1感染症成人患者を対象とする3件のピボタル第3相試験の結果を発表しました。 |
| 2026-02-25 | Merck Sharp & Dohme LLC | Results Merck Announces Late-Breaking Data from Three Phase 3 Trials Evaluating Doravirine/Islatravir (DOR/ISL), an Investigational, Once-Daily, Two-Drug Regimen for the Treatment of Adults Living with HIV-1 at CROI 2026 merck.com ↗
DOR/ISL is the first non-INSTI, two-drug regimen to demonstrate non-inferiority and a similar safety profile at Week 48 to BIC/FTC/TAF in adults living with HIV-1 who had not previously received antiretroviral treatment |
| 2025-11-19 | Merck Sharp & Dohme LLC | Results Merck Announces Positive Topline Results from the Pivotal Phase 3 Trial Evaluating Investigational, Once-Daily, Oral, Two-Drug, Single-Tablet Regimen of Doravirine/Islatravir (DOR/ISL) in Treatment-Naïve Adults with HIV-1 Infection merck.com ↗
The success criterion for the primary efficacy hypothesis, as measured by the percentage of participants with HIV-1 RNA levels <50 copies/mL at Week 48, was met, with DOR/ISL demonstrating non-inferiority to once-daily oral bictegravir/emtricitabine/tenofovir alafenamide i [BIC/FTC/TAF (50 mg/200 mg/25 mg)]. |
| 2025-10-15 | Merck Sharp & Dohme LLC | Results Merck Announces New Data from Phase 3 Trials Evaluating the Investigational, Once-Daily, Oral, Two-Drug Regimen of Doravirine/Islatravir (DOR/ISL) in Adults with Virologically Suppressed HIV-1 Infection merck.com ↗
In trial MK-8591A-052, adults living with virally suppressed HIV-1 infection who switched to DOR/ISL from BIC/FTC/TAF showed minimal changes in weight and body composition at Week 48 (exploratory endpoints). |
| 2025-10-15 | Gilead Sciences | Results Gilead Presents New HIV Research Data at EACS 2025 – Driving Scientific Innovation in Treatment and Prevention gilead.com ↗
The investigational combination has the potential to be the first twice-yearly complete regimen. |
| 2025-07-10 | Merck Sharp & Dohme LLC | Regulatory U.S. FDA Accepts New Drug Application for Merck’s Doravirine/Islatravir, an Investigational, Once-Daily, Oral, Two-Drug Regimen for Treatment of Adults with Virologically Suppressed HIV-1 Infection merck.com ↗
Merck (NYSE: MRK), known as MSD outside of the United States and Canada, today announced that the U.S. Food and Drug Administration (FDA) has accepted for review the New Drug Application (NDA) for doravirine/islatravir (DOR/ISL) |
| 2025-03-12 | Merck Sharp & Dohme LLC | Results Merck Announces Positive Data from Phase 3 Trials that Show the Investigational, Once-Daily, Oral, Two-Drug Regimen of Doravirine/Islatravir (DOR/ISL) Maintained HIV-1 Viral Suppression at Week 48 merck.com ↗
In both trials, DOR/ISL met the primary efficacy success criterion for non-inferiority to comparator antiretroviral therapies and primary safety objectives at Week 48. |
| 2025-01-14 | MSD R&D (China) Co., Ltd. | Results Merck & Co., Inc., Rahway, NJ, USA、ウイルス学的抑制が得られているHIV-1感染症成人患者の治療薬として1日1回経口投与のドラビリン／イスラトラビル（DOR/ISL）2剤配合錠を評価するピボタル第3相試験のトップラインデータを発表 msd.co.jp ↗
DOR/ISLは、非盲検のMK-8591A-051試験でbARTに対する非劣性、二重盲検のMK-8591A-052試験でBIC/FTC/TAFに対する非劣性を示しました。 |
| 2024-12-19 | Merck Sharp & Dohme LLC | Results Merck Announces Topline Results from Pivotal Phase 3 Trials Evaluating Investigational, Once-Daily, Oral, Two-Drug, Single-Tablet Regimen of Doravirine/Islatravir (DOR/ISL) for the Treatment of Adults with Virologically Suppressed HIV-1 Infection merck.com ↗
The success criterion for the primary efficacy hypothesis, as measured by the percentage of participants with HIV-1 RNA levels ≥50 copies/mL at Week 48, was met in both trials. |
| 2024-10-19 | Merck Sharp & Dohme LLC | Results Gilead and Merck Announce Phase 2 Data Showing a Treatment Switch to an Investigational Oral Once-Weekly Combination Regimen of Islatravir and Lenacapavir Maintained Viral Suppression in Adults at Week 48 merck.com ↗
At 48 weeks, the novel investigational combination maintained a high rate (n=49; 94.2%) of viral suppression (HIV-1 RNA <50 copies/mL) in virologically suppressed adults, a secondary endpoint of the study. |
| 2024-03-06 | Merck Sharp & Dohme LLC | Results Gilead and Merck Announce Phase 2 Data Showing an Investigational Oral Once-Weekly Combination Regimen of Islatravir and Lenacapavir Maintained Viral Suppression at Week 24 merck.com ↗
At 24 weeks, the novel investigational combination maintained a high rate (94.2%) of viral suppression (HIV-1 RNA <50 copies/mL), which is a secondary endpoint of the study. |
| 2021-12-13 | Merck Sharp & Dohme LLC | Regulatory Merck Announces Clinical Holds on Studies Evaluating Islatravir for the Treatment and Prevention of HIV-1 Infection merck.com ↗
The FDA’s clinical hold is based on previously announced observations of decreases in total lymphocyte and CD4+ T-cell counts in some participants receiving islatravir in clinical studies. |
| 2021-11-18 | Merck Sharp & Dohme LLC | Results Merck Provides Update on Phase 2 Clinical Trial of Once-Weekly Investigational Combination of MK-8507 and Islatravir for the Treatment of People Living with HIV-1 merck.com ↗
Decreases in total lymphocyte and CD4+ T-cell counts were observed in study participants randomized to receive ISL+MK-8507. |
| 2021-10-27 | Merck Sharp & Dohme LLC | Results Merck Presents New Data from Ongoing Phase 2b Clinical Trial Evaluating Efficacy and Safety of Investigational Islatravir in Combination With Doravirine Through 144 Weeks for HIV-1 Treatment at EACS 2021 merck.com ↗
Phase 2b data through 144 weeks demonstrated that islatravir combined with doravirine continued to maintain viral suppression, as measured by the number of study participants achieving HIV-1 RNA levels <50 copies/mL, similar to DOR/3TC/TDF. |
| 2021-10-25 | Merck Sharp & Dohme LLC | Results Merck Announces Positive Top-Line Results from Pivotal Phase 3 Trials Evaluating Investigational, Once-Daily Oral Fixed Dose Combination of Doravirine/Islatravir for the Treatment of People with HIV-1 Infection merck.com ↗
At 48 weeks, both trials met their primary efficacy endpoint of percentage of participants with HIV-1 RNA levels ≥50 copies/mL, demonstrating that antiviral efficacy was comparable between DOR/ISL and ART (ILLUMINATE SWITCH A) and between DOR/ISL and BIC/FTC/TAF (ILLUMINATE SWITCH B). |
| 2021-07-20 | Merck Sharp & Dohme LLC | Results Merck Presents New Data from Ongoing Phase 2a Clinical Trial Evaluating the Safety, Tolerability and Pharmacokinetics of Investigational, Once-Monthly, Oral Islatravir for HIV-1 Prevention at IAS 2021 merck.com ↗
After 24 weeks, once-monthly oral islatravir was generally well tolerated versus placebo. |
| 2021-07-12 | Merck Sharp & Dohme LLC | Results Merck Announces Presentation of New Data from Broad HIV Program at IAS 2021 merck.com ↗
No Pharmacokinetic Interaction Between Novel NNRTI MK-8507 and Islatravir. |
| 2021-03-08 | Merck Sharp & Dohme LLC | Results Merck Presents Results from Phase 1 Trial Evaluating Investigational Islatravir Subdermal Implant for the Prevention of HIV-1 Infection at CROI 2021 merck.com ↗
We are delighted to share our early data at CROI 2021 supporting the potential for a once-yearly dosing regimen for islatravir using a subdermal implant |
| 2021-01-26 | Merck Sharp & Dohme LLC | Results Merck Presents Interim Findings from Phase 2a Clinical Trial Evaluating Investigational Once-Monthly Oral Islatravir for the Prevention of HIV-1 Infection at HIVR4P 2021 merck.com ↗
Interim findings demonstrate that once-monthly oral islatravir achieved the pre-specified efficacy PK threshold for PrEP at both of the two doses studied (60 mg and 120 mg). |
| 2020-10-08 | Merck Sharp & Dohme LLC | Results Merck Announces Week 96 Data from Phase 2b Study Evaluating Islatravir in Combination With Doravirine in Adults With HIV-1 Infection merck.com ↗
Week 96 findings demonstrated that the combination of islatravir and doravirine maintained virologic suppression (as measured by the number of study participants achieving HIV-1 RNA levels <50 copies/mL, similar to DELSTRIGO™ (doravirine/lamivudine/tenofovir disoproxil fumarate)), and the findings were consistent with Week 48 results. |
| 2020-07-06 | Merck Sharp & Dohme LLC | Results Merck Announces New Analyses Showing Additional Safety and Efficacy Data for Investigational Islatravir in Combination with Doravirine in Adults with HIV-1 Infection merck.com ↗
The first sub-analysis further characterized the tolerability and safety profile of islatravir in combination with doravirine (100 mg) through Week 48 across the three dose levels studied (0.25, 0.75, 2.25 mg). |
| 2020-03-02 | Merck Sharp & Dohme LLC | Results Merck Announces New Data from Broad HIV Program at CROI 2020 merck.com ↗
Weekly Oral Islatravir Provides Effective PEP Against IV Challenge with SIVmac251. |
| 2019-07-24 | Merck Sharp & Dohme LLC | Results Merck Announces Presentation of Phase 2b Results for Investigational HIV-1 Therapy Islatravir (MK-8591) at IAS 2019 merck.com ↗
At all dose levels, the combination of islatravir and doravirine maintained antiviral activity as measured by the number of study participants achieving HIV-1 RNA levels <50 copies/mL, similar to DELSTRIGO at Week 48 of the study. |
| 2019-07-23 | Merck Sharp & Dohme LLC | Results Merck Presents Early Evidence on Extended Delivery of Investigational Anti-HIV-1 Agent Islatravir (MK-8591) via Subdermal Implant merck.com ↗ |
All press releases naming this drug 49 releases
Evidence & citations 10 cited values
Every value below carries the sentence it was read from. 32 sources stand behind the page.
| Field | Value | Cited text |
|---|---|---|
| Known as | islatravir | “The goal of this clinical study is to learn about the safety and efficacy of switching to once weekly tablet of islatravir/lenacapavir (ISL/LEN) regimen versus continuing...” NCT06630286 ↗26“This is a phase 2 study of the pharmacokinetics, safety, and efficacy of oral doravirine/islatravir (100 mg/0.25 mg) \[MK-8591A\] in pediatric participants with human...” NCT07862569 ↗ “received either doravirine (100 mg) and islatravir (0·25 mg) or bictegravir (50 mg), emtricitabine (200 mg), and tenofovir alafenamide (25 mg) orally once daily.” PMID 41763226 ↗ Feb 2026 “The goal of this study is to learn what happens to doravirine (DOR) and islatravir (ISL) in a healthy lactating female's body over time.” NCT07086079 ↗ “Once-weekly oral islatravir plus lenacapavir (ISL+LEN) has the potential to address adherence challenges with daily HIV-1 treatment.” PMID 41429026 ↗ Dec 2025 “Single tablet combination of 100 mg doravirine (DOR) with 0.25 mg Islatravir (ISL) in tablet form, taken orally, once daily.” NCT05631093 ↗ “Doravirine/Islatravir (DOR/ISL) in Pediatric Participants With Human Immunodeficiency Virus Type 1 (HIV-1)” NCT04295772 ↗ “FDC tablet of 100 mg doravirine, 0.75 mg islatravir taken orally, once daily for up to 192 weeks” NCT04776252 ↗ “FDC tablet of 100 mg doravirine (DOR)/0.25 mg islatravir (ISL) taken once daily” NCT05766501 ↗ “oral Islatravir (ISL) once monthly (QM) as Preexposure Prophylaxis (PrEP)” NCT04652700 ↗ “doravirine (100 mg) and islatravir (0·75 mg)” NCT04223791 ↗ |
| Known as | ISL | “Islatravir (also known as ISL and MK-8591) is a unique nucleoside reverse transcriptase translocation inhibitor in clinical development for treatment of people with HIV-1 infection.” PMID 31911147 ↗ Jan 202010“The goal of this study is to learn what happens to doravirine (DOR) and islatravir (ISL) in a healthy lactating female's body over time.” NCT07086079 ↗ “Once-weekly oral islatravir plus lenacapavir (ISL+LEN) has the potential to address adherence challenges with daily HIV-1 treatment.” PMID 41429026 ↗ Dec 2025 “Islatravir (ISL) is a nucleoside reverse transcriptase translocation inhibitor in development for the treatment of HIV-1 infection.” PMID 40042304 ↗ Mar 2025 “Single tablet combination of 100 mg doravirine (DOR) with 0.25 mg Islatravir (ISL) in tablet form, taken orally, once daily.” NCT05631093 ↗ “FDC tablet of 100 mg doravirine (DOR)/0.25 mg islatravir (ISL) taken once daily” NCT05766501 ↗ “oral Islatravir (ISL) once monthly (QM) as Preexposure Prophylaxis (PrEP)” NCT04652700 ↗ “Group 1: Doravirine/Islatravir (DOR/ISL)” NCT04223778 ↗ “islatravir/lenacapavir (ISL/LEN) regimen” NCT06630299 ↗ |
| Known as | Islatravir anhydrous | ChEMBL registry synonym — accepted as the source's own label CHEMBL517231 ↗ |
| Known as | ISLATRAVIR HYDRATE | ChEMBL registry synonym — accepted as the source's own label CHEMBL517231 ↗ |
| Known as | Islatravir monohydrate | ChEMBL registry synonym — accepted as the source's own label CHEMBL517231 ↗ |
| Known as | MK-8591 | ChEMBL registry synonym — accepted as the source's own label CHEMBL517231 ↗ |
| Known as | MK-8591 MONOHYDRATE | ChEMBL registry synonym — accepted as the source's own label CHEMBL517231 ↗ |
| Action | Inhibit | “a unique nucleoside reverse transcriptase translocation inhibitor” PMID 31911147 ↗ Jan 2020 |
| Modality | Other / unclassified | “a unique nucleoside reverse transcriptase translocation inhibitor” PMID 31911147 ↗ Jan 2020 |
| Route | Oral | “receiving a single oral dose of islatravir” PMID 31911147 ↗ Jan 2020 |