Enfuvirtide (Fuzeon)

Published March 17, 2003; Updated September 21, 2007
Susa Coffey, MD
http://hivinsite.ucsf.edu/InSite?page=ar-04-01
Selected References
1. Lalezari  JP, Henry  K, O'Hearn  M, Montaner  JS, Piliero  PJ, Trottier  B, Walmsley  S, Cohen  C, Kuritzkes  DR, Eron  JJ, Chung  J, DeMasi  R, Donatacci  L, Drobnes  C, Delehanty  J, Salgo  M; TORO 1 Study Group.
Enfuvirtide, an HIV-1 fusion inhibitor, for drug-resistant HIV infection in North and South America. N Engl J Med. 2003 May;348(22):2175-85
[PubMed ID: 12637625]
Abstract:
BACKGROUND: The T-20 vs. Optimized Regimen Only Study 1 (TORO 1) was a randomized, open-label, phase 3 study of enfuvirtide (T-20), a human immunodeficiency virus type 1 (HIV-1) fusion inhibitor. METHODS: Patients from 48 sites in the United States, Canada, Mexico, and Brazil with at least six months of previous treatment with agents in three classes of antiretroviral drugs, resistance to drugs in these classes, or both, and with at least 5000 copies of HIV-1 RNA per milliliter of plasma were randomly assigned in a 2:1 ratio to receive enfuvirtide plus an optimized background regimen of three to five antiretroviral drugs or such a regimen alone (control group). The primary efficacy end point was the change in the plasma HIV-1 RNA level from base line to week 24. RESULTS: A total of 501 patients underwent randomization, and 491 received at least one dose of study drug and had at least one measurement of plasma HIV-1 RNA after treatment began. The two groups were balanced in terms of the median base-line HIV-1 RNA level (5.2 log10 copies per milliliter in both groups), median CD4+ cell count (75.5 cells per cubic millimeter in the enfuvirtide group, and 87.0 cells per cubic millimeter in the control group), demographic characteristics, and previous antiretroviral therapy. At 24 weeks, the least-squares mean change from base line in the viral load (intention-to-treat, last observation carried forward) was a decrease of 1.696 log10 copies per milliliter in the enfuvirtide group, and a decrease of 0.764 log10 copies per milliliter in the control group (P<0.001). The mean increases in CD4+ cell count were 76 cells per cubic millimeter and 32 cells per cubic millimeter, respectively (P<0.001). Reactions at the site of the injections were reported by 98 percent of patients receiving enfuvirtide. There were more cases of pneumonia in the enfuvirtide group than in the control group. CONCLUSIONS: The addition of enfuvirtide to an optimized antiretroviral regimen provided significant antiretroviral and immunologic benefit through 24 weeks in patients who had previously received multiple antiretroviral drugs and had multidrug-resistant HIV-1 infection.
2. Lazzarin  A, Clotet  B, Cooper  D, Reynes  J, Arastéh  K, Nelson  M, Katlama  C, Stellbrink  HJ, Delfraissy  JF, Lange  J, Huson  L, DeMasi  R, Wat  C, Delehanty  J, Drobnes  C, Salgo  M; TORO 2 Study Group.
Efficacy of enfuvirtide in patients infected with drug-resistant HIV-1 in Europe and Australia. N Engl J Med. 2003 May;348(22):2186-95
[PubMed ID: 12773645]
Abstract:
BACKGROUND: The T-20 vs. Optimized Regimen Only Study 2 (TORO 2) compared the efficacy and safety of 24 weeks of treatment with the fusion inhibitor enfuvirtide in combination with an optimized background antiretroviral regimen with the efficacy and safety of the optimized background regimen alone. METHODS: The patients had previous treatment with each of the three classes of antiretroviral drugs, documented resistance to each class, or both and a plasma level of human immunodeficiency virus type 1 (HIV-1) RNA of at least 5000 copies per milliliter. They were randomly assigned in a 2:1 ratio to receive either enfuvirtide (90 mg twice daily) plus a background regimen optimized with the aid of resistance testing (enfuvirtide group) or the background regimen alone (control group). RESULTS: Of the 512 patients who underwent randomization, 335 in the enfuvirtide group and 169 in the control group received at least one dose of study medication and had at least one follow-up measurement of plasma HIV-1 RNA. The median base-line plasma HIV-1 RNA level was 5.1 log10 copies per milliliter in both groups. The median CD4+ cell count was 98.0 cells per cubic millimeter in the enfuvirtide group and 101.5 cells per cubic millimeter in the control group. Patients had a median of seven years of previous treatment and had received a median of 12 antiretroviral drugs. The background regimen comprised a mean of four antiretroviral drugs in both groups. At 24 weeks, the least-squares mean change from base line in the plasma viral load (intention-to-treat, last observation carried forward) was a decrease of 1.429 log10 copies per milliliter in the enfuvirtide group and a decrease of 0.648 log10 copies per milliliter in the control group, a difference of 0.781 log10 copies per milliliter (P<0.001). The mean increase in the CD4+ cell count was greater in the enfuvirtide group (65.5 cells per cubic millimeter) than in the control group (38.0 cells per cubic millimeter, P=0.02). CONCLUSIONS: The addition of enfuvirtide to an optimized background regimen provided significant viral suppression and immunologic benefit over a 24-week period in HIV-1-infected patients who had previously received multiple antiretroviral drugs.
3. Nelson  M, Arastéh  K, Clotet  B, Cooper  DA, Henry  K, Katlama  C, Lalezari  JP, Lazzarin  A, Montaner  JS, O'Hearn  M, Piliero  PJ, Reynes  J, Trottier  B, Walmsley  SL, Cohen  C, Eron  JJ, Kuritzkes  DR, Lange  J, Stellbrink  HJ, Delfraissy  JF, Buss  NE, Donatacci  L, Wat  C, Smiley  L, Wilkinson  M, Valentine  A, Guimaraes  D, Demasi  R, Chung  J, Salgo  MP.
Durable efficacy of enfuvirtide over 48 weeks in heavily treatment-experienced HIV-1-infected patients in the T-20 versus optimized background regimen only 1 and 2 clinical trials. J Acquir Immune Defic Syndr. 2005 Dec;40(4):404-12
[PubMed ID: 16280694]
Abstract:
BACKGROUND: The T-20 Versus Optimized Background Regimen Only (TORO) 1 and TORO 2 clinical trials are open-label, controlled, parallel-group, phase 3 studies comparing enfuvirtide plus an optimized background (OB) of antiretrovirals (n = 661) with OB alone (n = 334) in treatment-experienced HIV-1-infected patients. METHODS: The primary objective at week 48 was to investigate durability of efficacy, as measured by the percentage of patients maintaining their week 24 response or improving. Efficacy analyses used the intent-to-treat population. RESULTS: A total of 73.7% of patients randomized to the enfuvirtide group remained on treatment through week 48 versus 21.3% originally randomized to the control group. At week 48, a higher proportion of week 24 responders maintained their response or were new responders in the enfuvirtide group than in the control group in each responder category: HIV-1 RNA level > or =1.0 log(10) change from baseline, <400 copies/mL and <50 copies/mL (37.4%, 30.4%, and 18.3% in the enfuvirtide group vs. 17.1%, 12.0%, and 7.8% in the control group, respectively; P < 0.0001 for all comparisons). CD4 cell count increases from baseline were twice as great in the enfuvirtide group as in the control group. CONCLUSION: These data demonstrate durable efficacy of enfuvirtide plus OB over 48 weeks.