MSD (Merck & Co) has secured a US approval for its two-drug human immunodeficiency virus (HIV) combination therapy, Idvynso (doravirine/islatravir), as the company looks to secure a slice of the lucrative market.
Once-daily Idvynso was given the US regulatory greenlight based on the results of the Phase III MK-8591A-051 and MK-8591A-052 (NCT05631093; NCT05630755) trials, which found that patients switched from Gilead’s SoC therapy, Biktarvy (bictegravir/emtricitabine/tenofovir alafenamide), maintained viral suppression at a non-inferior level when taking Idvynso daily.
This means that American patients who are virologically suppressed and on a stable antiretroviral (ART) regimen can now be switched to Idvynso, provided they have not previously experienced virologic treatment failure or doravirine resistance.
According to Anaelle Tannen, infectious disease analyst at GlobalData, Idvynso’s regulatory greenlight reflects a broader shift in the HIV treatment landscape away from traditional three-drug combinations toward simpler, potentially more tolerated options.
Currently, the HIV market is dominated by Gilead’s three-drug regimen, Biktarvy, though GSK’s dual therapy, Dovato (dolutegravir/lamivudine), also holds a strong share. Unlike Biktarvy and Dovato, however, Idvynso does not contain an integrase strand transfer inhibitor (INSTI), which can be linked to tolerability issues.
Because of its departure from reliance on INSTIs, Tannen says that Idvynso will likely see virologically suppressed patients switch, particularly those who need alternatives due to “tolerability or class-related issues”.
However, Tannen does not foresee Idvynso displacing established first-line SoC therapies like Biktarvy, as they have better physician familiarity and established safety and efficacy in HIV. According to patient-based forecasts from GlobalData, parent company of Pharmaceutical Technology, Biktarvy’s sales will peak at $13.2bn in 2032, while Idvynso will pull in $1.6bn that same year.
For Idvynso to differentiate itself in the long term, Tannen notes that the drug must demonstrate “clear advantages in weight neutrality or reduced metabolic impact”, which has been a side effect linked to INSTIs like dolutegravir and bictegravir.
Idvynso’s combinatory potential
While analysts do not predict that Idvynso will have a SoC-changing market impact as a monotherapy, MSD is taking another shot at glory on the HIV market through a late-stage combination programme, which will see the company gauge the potential of Idvynso plus Gilead’s HIV drug, Sunlenca (lenacapavir), as a once-weekly treatment option.
The therapeutic duo has already shown promise in a Phase II trial, where it maintained viral suppression on a weekly dosing regimen for two years. If approved, Idvynso-Sunleca could become the first oral treatment option for HIV with this dosing pattern.
A recent report from GlobalData projects the global HIV marketplace to experience modest growth during the forecast period, as the indication becomes increasingly competitive.
