Study of the efficacy of initial intensification with enfuvirtide in a first-line triple therapy regimen in HIV-1-infected patients with severe immunodeficiency
Last updated on 24 September 2025
The aim of the Apollo study is to investigate whether enfuvirtide (ENF) added to basic combination antiretroviral therapy (cART) improves the CD4 cell count response at week 24 in treatment-naive patients with advanced HIV disease.
The primary objective of the trial is to study the immunological efficacy at week 24 of an induction-maintenance strategy using initial intensification of antiretroviral triple therapy with enfuvirtide. The efficacy of this strategy is being evaluated in a randomised manner in HIV-1-infected patients who are antiretroviral-naive and have severe immunodeficiency leading to a high risk of clinical disease progression. These patients receive a combination of antiretroviral drugs including emtricitabine/tenofovir disoproxil fumarate, efavirenz or lopinavir/ritonavir, initially intensified or not with enfuvirtide.
The analysis included 194 participating patients (100 in the ‘intensification’ group and 94 in the ‘standard’ group).
The majority of patients were male, with an average age of 44, and were in an advanced stage of the disease, with severe immunodeficiency and high HIV viremia. 81% of patients received lopinavir/ritonavir and 19% received efavirenz (antiretroviral drug chosen by the investigator).
At week 24, 34% of patients in the ‘intensification’ group and 38% of those in the ‘standard’ group had CD4 counts ≥200/mm3 (primary endpoint, p=0.53). The proportions of patients with plasma HIV-1 RNA <50 copies/ml were 74% and 58% at week 24, respectively (p<0.02). At week 48, 79% of patients had viraemia <50 copies/ml in both groups.
The conclusion of the Apollo study is that the addition of enfuvirtide to standard triple therapy in patients with severe immunodeficiency and high HIV viral replication did not induce a higher CD4 immune response at 48 weeks. Nevertheless, the decline in viraemia was faster in the group receiving intensified treatment. The treatments were generally well tolerated with expected side effects, and discontinuation of enfuvirtide was most often due to difficulties in using this drug.
For more details, see the fact sheets available at the bottom of this page.
The secondary objectives of the Apollo study were to compare the two groups (with or without enfuvirtide intensification) at week 24 and week 48:
Pathology
HIV
Status
Completed
Number of participants
220
Sponsorship
ANRS MIE
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