Safety and Efficacy of Reduced Versus Standard Dose Efavirenz (EFV) Plus Two Nucleotides in Antiretroviral-naïve Adults. (ENCORE1)

A Randomised, Double-blind, Placebo-controlled, Trial to Compare the Safety and Efficacy of Reduced Dose Versus Standard Dose EFV Plus Two Nucleotides (N(t)RTI) in Antiretroviral-naïve HIV-infected Adults Over 96 Weeks

Clinical data suggests that the standard dose of the anti-HIV medication, efavirenz (EFV), could be reduced without compromising its effectiveness. Lower drug doses could have fewer side effects and would make EFV more affordable. The purpose of this study is to compare the safety and effectiveness, over 96 weeks, of standard (600mg) versus reduced dose (400mg) EFV in controlling HIV as part of initial combination antiretroviral therapy.

Study Overview

• Status: Completed
• Conditions: HIV Infections
• Intervention / Treatment: Drug: Efavirenz 600mg; Drug: Efavirenz 400mg

Detailed Description

In this international, multicenter trial, 630 HIV infected patients who have not received any previous treatment for their HIV-infection will be enrolled. Participants will be randomized equally (1:1) to receive Truvada (tenofovir and emtricitabine) with either the standard or reduced dose of EFV. Neither the study doctor nor the participant will know which treatment the participant is receiving. Physical examinations, laboratory analyses and questionnaires will be performed at the 11 study visits at screening, baseline (Week 0), Weeks 4, 12, 24, 36, 48, 60, 72, 84 and 96. The primary aim of this study is to compare between treatment groups the proportion of patients with undetectable HIV viral load (HIV RNA < 200 copies/mL) after 48 weeks. Information on immune function, drug adherence, resistance to antiretrovirals, quality of life, mental state and HIV-related conditions will also be collected. Blood samples will be collected for future testing. Interim analyses will be performed when the first 125 participants in each treatment group reach week 24 and when all participants reach week 24. These interim analyses will provide an early check that the reduced dose of EFV suppresses HIV infection as effectively as the standard dose of EFV. A follow-up analysis will be performed when all participants reach week 96.

• Study Type: Interventional
• Enrollment (Actual): 636
• Phase: Phase 3

Contacts and Locations

Study Locations

• Australia
  • New South Wales
    • Sydney, New South Wales, Australia, 2010
      • St Vincent's Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 16 years and older (ADULT, OLDER_ADULT, CHILD)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• HIV-1 positive by licensed diagnostic test
• aged >16 years of age (or minimum age as determined by local regulations or as legal requirements dictate)
• 50 < cluster of differentiation (CD)4 <500 cells/µL
• No prior AIDS-defining illness, using the Center for Diseases Control 1993 Case Definition (except pulmonary tuberculosis)
• HIV RNA ≥1000 copies/mL
• no prior exposure to antiretroviral therapy (ART) (including short course ART for preventing MTCT)
• calculated creatinine clearance (CLCr) more than or equal to 50 mL/min (Cockcroft-Gault formula)
• provision of written informed consent.

Exclusion Criteria:

• the following laboratory values:

  • absolute neutrophil count (ANC) <500 cells/μL
  • hemoglobin <7.0 g/dL
  • platelet count <50,000 cells/μL
  • alanine aminotransferase and/or aspartate aminotransferase >5 x upper limit of normal
• pregnant women or nursing mothers
• active opportunistic or malignant disease not under adequate control
• use of immunomodulators within 30 days prior to screening
• use of any prohibited medications
• current alcohol or illicit substance use that might adversely affect study participation

Study Plan

How is the study designed?

Design Details

• Primary Purpose: TREATMENT
• Allocation: RANDOMIZED
• Interventional Model: PARALLEL
• Masking: DOUBLE

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
ACTIVE_COMPARATOR: 600 milligram (mg) Efavirenz; Eligible patients will be centrally randomised to receive tenofovir (TDF) (300mg qd)/emtricitabine (FTC) (200mg qd) + EFV (600mg qd; 3 x 200mg qd)	Drug: Efavirenz 600mg; 3 x EFV 200 milligram (mg) tablets once daily; Other Names: Matrix EFV 200mg tablets
EXPERIMENTAL: 400mg Efavirenz; Eligible patients will be centrally randomised to receive TDF (300mg qd)/FTC (200mg qd) + EFV (400mg qd; 2 x 200mg + 1 x 200mg placebo qd).	Drug: Efavirenz 400mg; 2 x EFV 200 milligram (mg) tablets plus 1x matched EFV placebo tablet once daily; Other Names: Matrix EFV 200mg tablets; Matrix EFV 200mg matched placebo tablets.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Percentage of Participants With Plasma HIV-1 RNA <200 Copies/mL 48 Weeks After Randomisation	Percentage of participants in each of the treatment arms with centrally quantified plasma HIV-1 RNA viral load <200 copies/mL 48 weeks after randomisation.	48 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Percentage of Participants With Plasma HIV-1 RNA <400 Copies/mL and <50 Copies/mL at 48 and 96 Weeks After Randomisation	Percentage of participants in each of the two treatment arms with plasma HIV-1 RNA <400 copies/mL and <50 copies/mL at 48 and 96 weeks after randomisation	Baseline and 2 years
Mean Change From Baseline in CD4+ T-cell Count	Mean change from baseline to week 96 in CD4+ T-cell count/mm3 between the two treatment arms	Baseline and 2 years
Clinical Endpoints: Opportunistic Disease or Death, and Serious Non-AIDS-defining Events and Non-AIDS-related Mortality	Number of participants in each randomised arm diagnosed with a serious non-AIDS defining event, who die from an AIDS-defining event, who die from a non-AIDS-defining event	up to 2 years
Change From Baseline in Metabolic Endpoints	Change from baseline to week 96 in fasted total cholesterol, high density cholesterol and low density cholesterol, and glucose between randomised treatment arms	Baseline and 2 years
Adherence: Median Scores of Self-reported Adherence to Randomised Study Medications	AIDS Clinical Trials Group (ACTG) 7-day adherence questionnaire scores. Maximum value is all pills taken every day; minimum value is no pills taken per day. Higher scores indicate a better outcome.	2 years
Change From Baseline in Fasted Insulin Levels	Change from baseline to week 96 in fasted insulin levels	Baseline and 2 years
Change in Selected Serum Biochemical Parameters	Change from baseline to week 96 in alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase levels between randomised treatment arms	Baseline and 2 years
Change From Baseline in Estimate Creatinine Clearance	Change from baseline to week 96 in estimate creatinine clearance between randomised treatment arms	Baseline and 2 years
Steady-state Efavirenz Concentrations	Steady-state efavirenz mid-dosing interval plasma concentrations	Week 4

Collaborators and Investigators

• Sponsor: Kirby Institute
• Investigators: Principal Investigator: David Cooper, Professor, Kirby Institute

Publications and helpful links

General Publications

• ENCORE1 Study Group. Efficacy of 400 mg efavirenz versus standard 600 mg dose in HIV-infected, antiretroviral-naive adults (ENCORE1): a randomised, double-blind, placebo-controlled, non-inferiority trial. Lancet. 2014 Apr 26;383(9927):1474-1482. doi: 10.1016/S0140-6736(13)62187-X. Epub 2014 Feb 10. Erratum In: Lancet. 2014 Apr 26;383(9927):1464.
• ENCORE1 Study Group; Carey D, Puls R, Amin J, Losso M, Phanupak P, Foulkes S, Mohapi L, Crabtree-Ramirez B, Jessen H, Kumar S, Winston A, Lee MP, Belloso W, Cooper DA, Emery S. Efficacy and safety of efavirenz 400 mg daily versus 600 mg daily: 96-week data from the randomised, double-blind, placebo-controlled, non-inferiority ENCORE1 study. Lancet Infect Dis. 2015 Jul;15(7):793-802. doi: 10.1016/S1473-3099(15)70060-5. Epub 2015 Apr 12. Erratum In: Lancet Infect Dis. 2015 Jul;15(7):761.
• Winston A, Amin J, Clarke A, Else L, Amara A, Owen A, Barber T, Jessen H, Avihingsanon A, Chetchotisakd P, Khoo S, Cooper DA, Emery S, Puls R; ENCORE Cerebrospinal Fluid (CSF) Substudy Team; ENCORE Cerebrospinal Fluid CSF Substudy Team. Cerebrospinal fluid exposure of efavirenz and its major metabolites when dosed at 400 mg and 600 mg once daily: a randomized controlled trial. Clin Infect Dis. 2015 Apr 1;60(7):1026-32. doi: 10.1093/cid/ciu976. Epub 2014 Dec 11. Erratum In: Clin Infect Dis. 2015 Jul 1;61(1):143. Avinghsanon, Anchalee [corrected to Avihingsanon, Anchalee].

Helpful Links

• Kirby Institute (formerly National Centre for HIV Epidemiology and Clinical Research)

Study record dates

Study Major Dates

• Study Start: August 1, 2011
• Primary Completion (ACTUAL): June 1, 2013
• Study Completion (ACTUAL): August 1, 2014

Study Registration Dates

• First Submitted: November 9, 2009
• First Submitted That Met QC Criteria: November 10, 2009
• First Posted (ESTIMATE): November 11, 2009

Study Record Updates

• Last Update Posted (ACTUAL): February 21, 2020
• Last Update Submitted That Met QC Criteria: February 18, 2020
• Last Verified: February 1, 2020

More Information

Terms related to this study

• Keywords: HIV; Dose reduction; Antiretroviral Therapy (ART); Efavirenz (EFV)
• Additional Relevant MeSH Terms: RNA Virus Infections; Virus Diseases; Infections; Blood-Borne Infections; Communicable Diseases; Sexually Transmitted Diseases, Viral; Sexually Transmitted Diseases; Lentivirus Infections; Retroviridae Infections; Immunologic Deficiency Syndromes; Immune System Diseases; HIV Infections; Molecular Mechanisms of Pharmacological Action; Anti-Infective Agents; Antiviral Agents; Reverse Transcriptase Inhibitors; Nucleic Acid Synthesis Inhibitors; Enzyme Inhibitors; Cytochrome P-450 Enzyme Inhibitors; Cytochrome P-450 Enzyme Inducers; Cytochrome P-450 CYP3A Inducers; Cytochrome P-450 CYP2B6 Inducers; Cytochrome P-450 CYP2C9 Inhibitors; Cytochrome P-450 CYP2C19 Inhibitors; Efavirenz
• Other Study ID Numbers: NCHECR-ENCORE1