Dual therapy consists of two active ingredients instead of the usual three. One possible advantage of dual therapy is that it contains fewer active ingredients than triple therapy, so it may cause fewer side effects. Dual therapy may also be less expensive than triple therapy.
First Approved Combination: Dolutegravir and Rilpivirine
In May 2017, I reported that the first dual therapy had been approved by the EMA. This first dual therapy consists on one pill which contains dolutegravir and rilpivirine. Findings from the SWORD-1 and SWORD-2 studies show that this drug is non-inferior in suppressing the virus in people with an undetectable viral load. This means that this dual therapy works just as well as various triple therapies with which it was compared. There were slightly fewer side effects for people who took dual therapy than for those who took triple therapy. Meanwhile, this drug is now available for prescription in the Netherlands.
New: Dolutegravir and Lamivudine
During AIDS2018, the results of the GEMINI-1 and GEMINI-2 studies were presented. These studies looked at whether dual therapy containing dolutegravir and lamivudine is effective and safe. These studies involved therapy-naive people. This means people who have never used HIV inhibitors before.
The GEMINI 1 and GEMINI 2 studies both have the same setup. Each study included around 700 people; one half of these people received dual therapy containing dolutegravir and lamivudine and the other received triple therapy containing dolutegravir, emtricitabine and tenofovir.
The studies found that after 48 weeks, the dual therapy was non-inferior to the triple therapy. In other words, both drugs were equally effective at suppressing the virus. About 92% of the group who received dual therapy had an undetectable viral load, compared with 94% of the group who received triple therapy.
However, it did appear that CD4 count had a huge impact on the effectiveness of this therapy for therapy-naive people. The participants who took dual therapy were divided into two groups: one group with more than 200 CD4 cells per mm3 of blood, and one group with fewer than 200 CD4 cells per mm3 of blood. In the group that had more than 200 CD4 cells, 93% had an undetectable viral load. In the group with fewer than 200 CD4 cells, this was only 79%.
There were slightly more side effects reported in the group that received triple therapy, but this difference is probably due to coincidence (it is not statistically significant). A request for approval for this drug is expected to be submitted to the EMA.
Cahn P et al. Non-inferior efficacy of dolutegravir (DTG) plus lamivudine (3TC) versus DTG plus tenofovir/emtricitabine (TDF/FTC) fixed-dose combination in antiretroviral treatment-naïve adults with HIV-1 infection – interim data from the GEMINI studies. 22nd International AIDS Conference (AIDS 2018), Amsterdam, abstract TUAB0106LB, 2018.