Merck Reveals Phase 3 Results for Once-Daily Doravirine/Islatravir HIV Treatment

Merck, operating as MSD outside the United States and Canada, has announced promising results from two critical Phase 3 clinical studies focused on a new once-daily treatment for adults with HIV-1. This investigational regimen combines doravirine and islatravir into a single oral tablet, aimed at patients whose infections are already controlled through existing antiretroviral therapies. The studies, identified as MK-8591A-051 and MK-8591A-052, explored the efficacy and safety of this new drug combination in comparison to current treatment options.

The primary goal of these trials was to evaluate the efficacy of doravirine/islatravir in maintaining viral suppression, measured by the proportion of participants with HIV-1 RNA levels of at least 50 copies per milliliter at 48 weeks. In both trials, the new regimen met the success criteria. The MK-8591A-051 trial established that doravirine/islatravir was comparable in effectiveness to baseline antiretroviral therapy, while the MK-8591A-052 trial determined it was similarly effective to another established regimen, bictegravir/emtricitabine/tenofovir alafenamide. Although the new regimen did not demonstrate superiority in the MK-8591A-052 trial, its safety profile was successfully achieved in both studies.

Merck plans to unveil more comprehensive data from these trials at an upcoming scientific conference and intends to submit these findings to regulatory bodies. Currently in the U.S., doravirine is available for adults with HIV-1 as a single agent branded as PIFELTRO, or as part of a multi-drug single-tablet combination known as DELSTRIGO.

Dr. Eliav Barr, Merck's senior vice president and head of global clinical development, expressed optimism about these findings, emphasizing the company’s commitment to advancing treatment options for individuals living with HIV. He highlighted the potential of islatravir, which is under extensive clinical evaluation for various dosing options and combinations with other antiretroviral agents.

Islatravir is classified as a nucleoside reverse transcriptase translocation inhibitor (NRTTI), offering innovative mechanisms for inhibiting HIV replication. In addition to the completed studies, further Phase 3 trials are ongoing. These trials include MK-8591A-053, assessing the efficacy of the regimen in patients new to HIV treatment, and MK-8591A-054, evaluating long-term effects in participants from earlier trials.

As for the available treatments, PIFELTRO and DELSTRIGO are indicated in the U.S. for adult patients with HIV-1 who are either treatment-naïve or virologically suppressed with no history of treatment failure and no known resistance mutations. These treatments are essential in maintaining viral suppression and ensuring patient health.

Merck also provides guidance on potential safety concerns related to these medications. For instance, patients should be tested for hepatitis B virus (HBV) before starting treatment, as discontinuation of certain components could exacerbate HBV infections. Additionally, potential drug interactions and side effects, such as severe skin reactions or renal impairment, are highlighted as considerations when prescribing these treatments.

A critical aspect of HIV treatment involves monitoring and managing side effects. The most common adverse reactions to DELSTRIGO include dizziness, nausea, and unusual dreams. As for PIFELTRO, users may experience nausea, dizziness, headache, fatigue, diarrhea, abdominal pain, and abnormal dreams. Long-term studies such as DRIVE-FORWARD and DRIVE-AHEAD have provided valuable insights into these potential side effects, ensuring healthcare providers can better manage patient outcomes.

Furthermore, Merck outlines the importance of assessing liver and kidney function during treatment, especially in cases of pre-existing conditions. The company is also focused on ensuring safe use during pregnancy and breastfeeding, encouraging healthcare providers to register pregnant patients with the Antiretroviral Pregnancy Registry for monitoring.

Through ongoing research and development, Merck remains committed to discovering and advancing new HIV treatment options. The company’s work over the past 35 years has led to significant scientific breakthroughs, providing hope and improved care for those affected by HIV. By continuously developing innovative therapies, Merck aims to reduce the global impact of HIV, striving for a future where the virus no longer defines individuals’ lives.