Investigational HIV Therapy Effectively Controls Virus in Treatment-Experienced Patients


Fostemsavir (ViiV Healthcare) may be a potential new option for patients with HIV who have become resistant to other medications.

The investigational treatment fostemsavir (ViiV Healthcare) demonstrated positive results in heavily treatment-experienced (HTE) patients with HIV, according to 48-week results from a phase 3 study.

Fostemsavir, a prodrug of the HIV-1 attachment inhibitor class temsavir, is currently being investigated in combination with other antiretroviral (ARV) agents in this patient population. The most recent data at 48 weeks from the phase 3 BRIGHTE study add to the primary endpoint data at 8 days, which were announced last year.

The trial evaluated the safety and efficacy of fostemsavir in 371 HTE adults with HIV-1 infection who had documented resistance, intolerability, and/or contraindication to all antiretroviral (ARV) agents in at least 4 of the 6 available ARV classes.

According to ViiV, fostemsavir does not have in-vitro cross-resistance to other classes of ARVs due to its mechanism of action, which may help patients who have become resistant to most other HIV therapies.

For the trial, patients were divided into 2 cohorts: randomized and non-randomized. Those in the randomized cohort had to have 1, but no more than 2, fully active ARV classes remaining at baseline and were unable to form a viable ARV regimen out of their remaining agents. Patients without any remaining fully-active approved ARVs were assigned to the non-randomized cohort.

Patients in the randomized cohort were either given blinded fostemsavir or blinded placebo in addition to their currently failing regimens for 8 days of functional monotherapy. The non-randomized cohort received open-label fostemsavir plus optimized background therapy (OBT) on day 1. The primary endpoint was mean change in log10 HIV-1 RNA between day 1 and day 8 in the randomized cohort. After day 8, patients in the randomized cohort received open-label fostemsavir plus OBT.

According to the data, fostemsavir maintained virologic suppression from week 24 to week 48 in combination with optimized background treatment (OBT). The results showed that 54% of patients in the randomized cohort achieved virologic suppression (<40 copies/mL) at 48 weeks of treatment. Additionally, patients in the randomized cohort showed immunologic improvement through week 48 as demonstrated by an increase in CD4+ T-cell counts (mean change from baseline of +139 cells/µL), according to the study.

Most patients treated with fostemsavir reported at least 1 adverse event (AE) by week 48, with the most commonly reported AEs being diarrhea, nausea, and headache. One or more serious AEs were reported in 35% of patients, mostly related to infections occurring in the most immunocompromised patients.

Based on these data, ViiV expects to seek regulatory approval for fostemsavir in 2019, according to the release.


ViiV Healthcare announces positive phase 3 results from the BRIGHTE study of fostemsavir in heavily treatment-experienced patients with HIV [news release]. ViiV’s website. Accessed November 7, 2018.

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