New Oral Islatravir/Doravirine Regimen Shows Strong Results in Two Phase 3 Studies

A new HIV treatment, a once-daily pill combining two antiviral drugs—Doravirine (DOR) and Islatravir (ISL) at a dosage of 100 mg and 0.25 mg, respectively—has shown promise in maintaining viral suppression in people living with HIV, according to recent Phase III clinical trials.

The studies, conducted by Merck & Co., Inc., suggest that switching to this new combination therapy is as effective as continuing with existing treatment regimens.

Why This Study Matters

For people living with HIV, maintaining an undetectable viral load is crucial for staying healthy and preventing the transmission of the virus. Many individuals currently take combination antiretroviral therapy (ART), which involves multiple medications. This new research indicates that switching to the once-daily DOR/ISL pill could provide a simpler, equally effective alternative.

Understanding the Studies

Researchers conducted two separate trials to evaluate the effectiveness and safety of switching to DOR/ISL:

1. The First Study: Included 513 participants who were already using Biktarvy (BIC/FTC/TAF), one of the most commonly prescribed single-tablet HIV treatments. This study specifically evaluated switching from this widely used standard regimen. Of these, 342 switched to DOR/ISL (100/0.25 mg), while 171 continued BIC/FTC/TAF.

2. The Second Study: Included 551 participants who were taking a variety of other oral ART regimens, covering all other standard HIV treatment combinations. This study evaluated switching from a broader range of treatment regimens. In this study, 366 switched to DOR/ISL (100/0.25 mg), while 185 continued their baseline ART.

In both studies, participants were randomly assigned to either continue their current treatment or switch to DOR/ISL. Scientists then measured whether the new treatment could keep their viral load suppressed after 48 weeks.

Key Findings

• In the first study, 91.5% of those who switched to DOR/ISL maintained an undetectable viral load, compared to 94.2% of those who continued their existing regimen.
• In the second study, 95.6% of those who switched to DOR/ISL remained undetectable, compared to 91.9% of those who stayed on their previous ART.
• Very few participants (less than 2%) experienced an increase in viral load after switching, showing that DOR/ISL was just as effective as other standard treatments.

What About Side Effects?

Both studies found that DOR/ISL was well tolerated, with side effects similar to existing HIV treatments. The most common issues were mild, including headaches, diarrhea, and fatigue. Serious side effects were rare, and only a small percentage of participants discontinued the new treatment due to adverse effects.

A Step Toward Simpler HIV Treatment

These results are promising for individuals who want a convenient, once-daily pill without compromising effectiveness. A simpler treatment regimen could improve adherence, making it easier for people to stay on their medication and maintain their health.

While further research and regulatory approvals are needed before DOR/ISL becomes widely available, these findings mark an important step toward more accessible and manageable HIV treatment options. If approved, this therapy could provide a new alternative for people living with HIV, seeking a simpler and equally effective regimen.

What’s Next?

Scientists will continue monitoring participants, to ensure long-term effectiveness and safety. If these positive results hold, DOR/ISL could become a key option in the evolving landscape of HIV treatment, offering hope for even more streamlined and effective care in the future.