Positive topline results were announced from two phase 3 trials evaluating doravirine/islatravir (DOR/ISL) in adults with HIV-1 infection who are virologically suppressed on different antiretroviral therapy regimens or bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF).

The randomized, double-blind ILLUMINATE SWITCH A (ClinicalTrials.gov Identifier: NCT04223778) and SWITCH B (ClinicalTrials.gov Identifier: NCT04223791) trials evaluated the investigational, oral DOR/ISL in adults with HIV-1 who are virologically suppressed. In SWITCH A (N=672) and B (N=641), patients were randomly assigned 1:1 to either switch to DOR/ISL once daily or continue with their current baseline antiretroviral regimen or BIC/FTC/TAF, respectively.

The primary endpoint was the percentage of patients with HIV-1 RNA levels greater than or equal to 50 copies/mL at week 48. Results showed comparable antiviral efficacy between DOR/ISL and prior antiretroviral therapy regimens as well as between DOR/ISL and BIC/FTC/TAF. The safety profile of DOR/ISL was consistent with the previously reported phase 2 studies.

Detailed trial findings will be presented at a future scientific congress and will form the basis of global regulatory applications.

Dr Joan Butterton, vice president, global clinical development, infectious diseases, Merck Research Laboratories, said: “We are encouraged by the results from the phase 3 ILLUMINATE SWITCH A and B trials, in which the DOR/ISL dual regimen efficacy was comparable to certain commonly used 3-drug regimens. We will continue to study doravirine/islatravir in diverse populations of people living with HIV and look forward to sharing data from these trials.”

Doravirine is marketed under the brand name Pifeltro and is indicated for use in combination with other antiretroviral agents for HIV-1 infection in antiretroviral treatment-naïve patients, or to replace the current antiretroviral regimen in virologically suppressed (HIV-1 RNA <50 copies/mL) patients on a stable antiretroviral regimen with no history of treatment failure and no known substitutions associated with resistance to doravirine.


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. News release. Merck. Accessed October 25, 2021. https://www.businesswire.com/news/home/20211025005274/en/Merck-Announces-Positive-Top-Line-Results-from-Pivotal-Phase-3-Trials-Evaluating-Investigational-Once-Daily-Oral-Fixed-Dose-Combination-of-DoravirineIslatravir-for-the-Treatment-of-People-with-HIV-1-Infection