Safety and Efficacy of Tenofovir DF in HIV-1 Infected Adolescents Failing Their Current Antiretroviral Therapy

• Time-weighted Average Change From Baseline Through Week 48 (DAVG48) in Plasma HIV-1 RNA [ Time Frame: Baseline to 48 weeks ] [ Designated as safety issue: No ]
  DAVG48 was defined as the time-weighted average between the first postbaseline value through the last value up to Week 48 minus the baseline value. DAVG48 was calculated using the trapezoidal rule with all available postbaseline data minus the baseline value.
• Change From Baseline to Week 24 in HIV-1 RNA [ Time Frame: Baseline to 24 weeks ] [ Designated as safety issue: No ]
  Change = Week 24 value minus baseline value
• Change From Baseline to Week 48 in HIV-1 RNA [ Time Frame: Baseline to 48 weeks ] [ Designated as safety issue: No ]
  Change = Week 48 value minus baseline value
• Change From Baseline to Week 96 in HIV-1 RNA [ Time Frame: Baseline to 96 weeks ] [ Designated as safety issue: No ]
  Change = Week 96 value minus baseline value
• Change From Baseline to Week 144 in HIV-1 RNA [ Time Frame: Baseline to 144 weeks ] [ Designated as safety issue: No ]
  Change = Week 144 value minus baseline value
• Change From Baseline to Week 192 in HIV-1 RNA [ Time Frame: Baseline to 192 weeks ] [ Designated as safety issue: No ]
• Change From Baseline to Week 240 in HIV-1 RNA [ Time Frame: Baseline to 240 weeks ] [ Designated as safety issue: No ]
• Change From Baseline to Week 288 in HIV-1 RNA [ Time Frame: Baseline to 288 weeks ] [ Designated as safety issue: No ]
• Change From Baseline to Week 336 in HIV-1 RNA [ Time Frame: Baseline to 336 weeks ] [ Designated as safety issue: No ]
• Change From Baseline to Week 24 in Cluster Determinant 4 (CD4) Count [ Time Frame: Baseline to 24 weeks ] [ Designated as safety issue: No ]
  Change = Week 24 value minus baseline value
• Change From Baseline to Week 48 in CD4 Count [ Time Frame: Baseline to 48 weeks ] [ Designated as safety issue: No ]
  Change = Week 48 value minus baseline value
• Change From Baseline to Week 96 in CD4 Count [ Time Frame: Baseline to 96 weeks ] [ Designated as safety issue: No ]
  Change = Week 96 value minus baseline value
• Change From Baseline to Week 144 in CD4 Count [ Time Frame: Baseline to 144 weeks ] [ Designated as safety issue: No ]
  Change = Week 144 value minus baseline value
• Change From Baseline to Week 192 in CD4 Count [ Time Frame: Baseline to 192 weeks ] [ Designated as safety issue: No ]
• Change From Baseline to Week 240 in CD4 Count [ Time Frame: Baseline to 240 weeks ] [ Designated as safety issue: No ]
• Change From Baseline to Week 288 in CD4 Count [ Time Frame: Baseline to 288 weeks ] [ Designated as safety issue: No ]
• Change From Baseline to Week 336 in CD4 Count [ Time Frame: Baseline to 336 weeks ] [ Designated as safety issue: No ]
• Change From Baseline to Week 24 in CD4 Percentage [ Time Frame: Baseline to 24 weeks ] [ Designated as safety issue: No ]
  Change = Week 24 value minus baseline value. CD4 percentage is the percentage of total lymphocytes that are CD4 cells.
• Change From Baseline to Week 48 in CD4 Percentage [ Time Frame: Baseline to 48 weeks ] [ Designated as safety issue: No ]
  Change = Week 48 value minus baseline value. CD4 percentage is the percentage of total lymphocytes that are CD4 cells.
• Change From Baseline to Week 96 in CD4 Percentage [ Time Frame: Baseline to 96 weeks ] [ Designated as safety issue: No ]
  Change = Week 96 value minus baseline value
• Change From Baseline to Week 144 in CD4 Percentage [ Time Frame: Baseline to 144 weeks ] [ Designated as safety issue: No ]
  Change = Week 144 value minus baseline value
• Change From Baseline to Week 192 in CD4 Percentage [ Time Frame: Baseline to 192 weeks ] [ Designated as safety issue: No ]
• Change From Baseline to Week 240 in CD4 Percentage [ Time Frame: Baseline to 240 weeks ] [ Designated as safety issue: No ]
• Change From Baseline to Week 288 in CD4 Percentage [ Time Frame: Baseline to 288 weeks ] [ Designated as safety issue: No ]
• Change From Baseline in Week 336 in CD4 Percentage [ Time Frame: Baseline to 336 weeks ] [ Designated as safety issue: No ]
• Percentage of Participants With an HIV-1 RNA Decrease of >= 1.0 log10 Copies/mL From Baseline to Week 24 [ Time Frame: Baseline to 24 weeks ] [ Designated as safety issue: No ]
  The percentage of participants achieving a plasma HIV-1 RNA decrease of >= 1.0 log10 copies/mL from baseline at Week 24 was summarized.
• Percentage of Participants With an HIV-1 RNA Decrease of >= 1.0 log10 Copies/mL From Baseline to Week 48 [ Time Frame: Baseline to 48 weeks ] [ Designated as safety issue: No ]
  The percentage of participants achieving a plasma HIV-1 RNA decrease of >= 1.0 log10 copies/mL from baseline at Week 48 was summarized.
• Percentage of Participants With an HIV-1 RNA Decrease of >= 1.0 log10 Copies/mL From Baseline to Week 96 [ Time Frame: Baseline to 96 weeks ] [ Designated as safety issue: No ]
  The percentage of participants achieving a plasma HIV-1 RNA decrease of >= 1.0 log10 copies/mL from baseline at Week 96 was summarized.
• Percentage of Participants With an HIV-1 RNA Decrease of >= 1.0 log10 Copies/mL From Baseline to Week 144 [ Time Frame: Baseline to 144 weeks ] [ Designated as safety issue: No ]
  The percentage of participants achieving a plasma HIV-1 RNA decrease of >= 1.0 log10 copies/mL from baseline at Week 144 was summarized.
• Percentage of Participants With an HIV-1 RNA Decrease of >= 1.0 log10 Copies/mL From Baseline to Week 192 [ Time Frame: Baseline to 192 weeks ] [ Designated as safety issue: No ]
• Percentage of Participants With an HIV-1 RNA Decrease of >= 1.0 log10 Copies/mL From Baseline to Week 240 [ Time Frame: Baseline to 240 weeks ] [ Designated as safety issue: No ]
• Percentage of Participants With an HIV-1 RNA Decrease of >= 1.0log10 Copies/mL From Baseline to Week 288 [ Time Frame: Baseline to 288 weeks ] [ Designated as safety issue: No ]
• Percentage of Participants With an HIV-1 RNA Decrease of >= 1.0log10 Copies/mL From Baseline to Week 336 [ Time Frame: Baseline to 336 weeks ] [ Designated as safety issue: No ]
• Percentage of Participants With HIV-1 RNA < 400 Copies/mL at Week 24 [ Time Frame: Week 24 ] [ Designated as safety issue: No ]
  The percentage of participants with plasma HIV-1 RNA < 400 copies/mL at Week 24 was summarized.
• Percentage of Participants With HIV-1 RNA < 400 Copies/mL at Week 48 [ Time Frame: Week 48 ] [ Designated as safety issue: No ]
  The percentage of participants with plasma HIV-1 RNA < 400 copies/mL at Week 48 was summarized.
• Percentage of Participants With HIV-1 RNA < 400 Copies/mL at Week 96 [ Time Frame: Week 96 ] [ Designated as safety issue: No ]
  The percentage of participants with plasma HIV-1 RNA < 400 copies/mL at Week 96 was summarized.
• Percentage of Participants With HIV-1 RNA < 400 Copies/mL at Week 144 [ Time Frame: Week 144 ] [ Designated as safety issue: No ]
  The percentage of participants with plasma HIV-1 RNA < 400 copies/mL at Week 144 was summarized.
• Percentage of Participants With HIV-1 RNA < 400 Copies/mL at Week 192 [ Time Frame: Week 192 ] [ Designated as safety issue: No ]
• Percentage of Participants With HIV-1 RNA < 400 Copies/mL at Week 240 [ Time Frame: Week 240 ] [ Designated as safety issue: No ]
• Percentage of Participants With HIV-1 RNA < 400 Copies/mL at Week 288 [ Time Frame: Week 288 ] [ Designated as safety issue: No ]
• Percentage of Participants With HIV-1 RNA < 400 Copies/mL at Week 336 [ Time Frame: Week 336 ] [ Designated as safety issue: No ]
• Percentage of Participants With HIV-1 RNA < 50 Copies/mL at Week 24 [ Time Frame: Week 24 ] [ Designated as safety issue: No ]
  The percentage of participants with plasma HIV-1 RNA < 50 copies/mL at Week 24 was summarized.
• Percentage of Participants With HIV-1 RNA < 50 Copies/mL at Week 48 [ Time Frame: Week 48 ] [ Designated as safety issue: No ]
  The percentage of participants with plasma HIV-1 RNA < 50 copies/mL at Week 48 was summarized.
• Percentage of Participants With HIV-1 RNA < 50 Copies/mL at Week 96 [ Time Frame: Week 96 ] [ Designated as safety issue: No ]
  The percentage of participants with plasma HIV-1 RNA < 50 copies/mL at Week 96 was summarized.
• Percentage of Participants With HIV-1 RNA < 50 Copies/mL at Week 144 [ Time Frame: Week 144 ] [ Designated as safety issue: No ]
  The percentage of participants with plasma HIV-1 RNA < 50 copies/mL at Week 144 was summarized.
• Percentage of Participants With HIV-1 RNA < 50 Copies/mL at Week 192 [ Time Frame: Week 192 ] [ Designated as safety issue: No ]
• Percentage of Participants With HIV-1 RNA < 50 Copies/mL at Week 240 [ Time Frame: Week 240 ] [ Designated as safety issue: No ]
• Percentage of Participants With HIV-1 RNA < 50 Copies/mL at Week 288 [ Time Frame: Week 288 ] [ Designated as safety issue: No ]
• Percentage of Participants With HIV-1 RNA < 50 Copies/mL at Week 336 [ Time Frame: Week 336 ] [ Designated as safety issue: No ]
• Percentage of Participants With Virologic Failure at Week 48 [ Time Frame: 48 weeks ] [ Designated as safety issue: No ]
  Virologic failure was defined as participants who never responded (response was defined as either a >= 0.5 log10 decrease from baseline in HIV-1 RNA in 2 consecutive visits or HIV-1 RNA < 400 copies/mL in 2 consecutive visits) or who had a rebound after achieving a response (rebound was defined as >= 1 log10 increase from nadir, or >= the baseline value, or > 1000 copies/mL in 2 consecutive visits). The virologic failure rate at Week 48 was estimated from Kaplan-Meier product limit method by including all HIV-1 RNA data collected during the double-blind phase.

• Time-weighted Average Change From Baseline Through Week 48 (DAVG48) in Plasma HIV-1 RNA [ Time Frame: Baseline to 48 weeks ] [ Designated as safety issue: No ]
  DAVG48 was defined as the time-weighted average between the first postbaseline value through the last value up to Week 48 minus the baseline value. DAVG48 was calculated using the trapezoidal rule with all available postbaseline data minus the baseline value.
• Change From Baseline to Week 24 in HIV-1 RNA. [ Time Frame: Baseline to 24 weeks ] [ Designated as safety issue: No ]
  Change = Week 24 value minus baseline value.
• Change From Baseline to Week 48 in HIV-1 RNA. [ Time Frame: Baseline to 48 weeks ] [ Designated as safety issue: No ]
  Change = Week 48 value minus baseline value.
• Change From Baseline to Week 24 in CD4 Count. [ Time Frame: Baseline to 24 weeks ] [ Designated as safety issue: No ]
  Change = Week 24 value minus baseline value.
• Change From Baseline to Week 48 in CD4 Count. [ Time Frame: Baseline to 48 weeks ] [ Designated as safety issue: No ]
  Change = Week 48 value minus baseline value.
• Change From Baseline to Week 24 in CD4 Percentage. [ Time Frame: Baseline to 24 weeks ] [ Designated as safety issue: No ]
  Change = Week 24 value minus baseline value. CD4 percentage is the percentage of total lymphocytes that are CD4 cells..
• Change From Baseline to Week 48 in CD4 Percentage. [ Time Frame: Baseline to 48 weeks ] [ Designated as safety issue: No ]
  Change = Week 48 value minus baseline value. CD4 percentage is the percentage of total lymphocytes that are CD4 cells.
• Percentage of Participants With an HIV-1 RNA Decrease of >= 1.0 log10 Copies/mL From Baseline to Week 24. [ Time Frame: Baseline to 24 weeks ] [ Designated as safety issue: No ]
  The percentage of participants achieving a plasma HIV-1 RNA decrease of >= 1.0 log10 copies/mL from baseline at Week 24 were summarized.
• Percentage of Participants With an HIV-1 RNA Decrease of >= 1.0 log10 Copies/mL From Baseline to Week 48. [ Time Frame: Baseline to 48 weeks ] [ Designated as safety issue: No ]
  The percentage of participants achieving a plasma HIV-1 RNA decrease of >= 1.0 log10 copies/mL from baseline at Week 48 were summarized.
• Percentage of Participants With HIV-1 RNA < 400 Copies/mL at Week 24. [ Time Frame: Week 24 ] [ Designated as safety issue: No ]
  The percentage of participants with plasma HIV-1 RNA < 400 copies/mL at Week 24 were summarized.
• Percentage of Participants With HIV-1 RNA < 400 Copies/mL at Week 48. [ Time Frame: Week 48 ] [ Designated as safety issue: No ]
  The percentage of participants with plasma HIV-1 RNA < 400 copies/mL at Week 48 were summarized.
• Percentage of Participants With HIV-1 RNA < 50 Copies/mL at Week 24. [ Time Frame: Week 24 ] [ Designated as safety issue: No ]
  The percentage of participants with plasma HIV-1 RNA < 50 copies/mL at Week 24 were summarized.
• Percentage of Participants With HIV-1 RNA < 50 Copies/mL at Week 48. [ Time Frame: Week 48 ] [ Designated as safety issue: No ]
  The percentage of participants with plasma HIV-1 RNA < 50 copies/mL at Week 48 were summarized.
• Percentage of Participants With Virologic Failure at Week 48 [ Time Frame: 48 weeks ] [ Designated as safety issue: No ]
  Participants who met the analysis definition of virologic failure (VF) were considered to have failed at the time of the first of two consecutive measurements. Time to VF for the 48-week analysis was assessed up to the date of the last nonmissing HIV-1 RNA assessment during the double-blind phase. The distribution of time to VF was estimated using the Kaplan-Meier product limit method. Participants without VF were censored at the time of their last HIV-1 RNA assessment prior to the extension phase, or at their last HIV assessment within 2 days of the last study drug dose.
• Change From Baseline to Week 96 in HIV-1 RNA. [ Time Frame: Baseline to 96 weeks ] [ Designated as safety issue: No ]
  Change = Week 96 value minus baseline value.
• Change From Baseline to Week 144 in HIV-1 RNA. [ Time Frame: Baseline to 144 weeks ] [ Designated as safety issue: No ]
  Change = Week 144 value minus baseline value.
• Change From Baseline to Week 192 in HIV-1 RNA. [ Time Frame: Baseline to 192 weeks ] [ Designated as safety issue: No ]
  Change = Week 192 value minus baseline value.
• Change From Baseline to Week 240 in HIV-1 RNA. [ Time Frame: Baseline to 240 weeks ] [ Designated as safety issue: No ]
  Change = Week 240 value minus baseline value.
• Change From Baseline to Week 96 in CD4 Count. [ Time Frame: Baseline to 96 weeks ] [ Designated as safety issue: No ]
  Change = Week 96 value minus baseline value.
• Change From Baseline to Week 144 in CD4 Count. [ Time Frame: Baseline to 144 weeks ] [ Designated as safety issue: No ]
  Change = Week 144 value minus baseline value.
• Change From Baseline to Week 192 in CD4 Count. [ Time Frame: Baseline to 192 weeks ] [ Designated as safety issue: No ]
  Change = Week 192 value minus baseline value.
• Change From Baseline to Week 240 in CD4 Count. [ Time Frame: Baseline to 240 weeks ] [ Designated as safety issue: No ]
  Change = Week 240 value minus baseline value.
• Change From Baseline to Week 96 in CD4 Percentage. [ Time Frame: Baseline to 96 weeks ] [ Designated as safety issue: No ]
  Change = Week 96 value minus baseline value. CD4 percentage is the percentage of total lymphocytes that are CD4 cells.
• Change From Baseline to Week 144 in CD4 Percentage. [ Time Frame: Baseline to 144 weeks ] [ Designated as safety issue: No ]
  Change = Week 144 value minus baseline value. CD4 percentage is the percentage of total lymphocytes that are CD4 cells.
• Change From Baseline to Week 192 in CD4 Percentage. [ Time Frame: Baseline to 192 weeks ] [ Designated as safety issue: No ]
  Change = Week 192 value minus baseline value. CD4 percentage is the percentage of total lymphocytes that are CD4 cells.
• Change From Baseline to Week 240 in CD4 Percentage. [ Time Frame: Baseline to 240 weeks ] [ Designated as safety issue: No ]
  Change = Week 240 value minus baseline value. CD4 percentage is the percentage of total lymphocytes that are CD4 cells.
• Percentage of Participants With an HIV-1 RNA Decrease of >= 1.0 log10 Copies/mL From Baseline to Week 96. [ Time Frame: Baseline to 96 weeks ] [ Designated as safety issue: No ]
  The percentage of participants achieving a plasma HIV-1 RNA decrease of >= 1.0 log10 copies/mL from baseline at Week 96 were summarized.
• Percentage of Participants With an HIV-1 RNA Decrease of >= 1.0 log10 Copies/mL From Baseline to Week 144. [ Time Frame: Baseline to 144 weeks ] [ Designated as safety issue: No ]
  The percentage of participants achieving a plasma HIV-1 RNA decrease of >= 1.0 log10 copies/mL from baseline at Week 144 were summarized.
• Percentage of Participants With an HIV-1 RNA Decrease of >= 1.0 log10 Copies/mL From Baseline to Week 192. [ Time Frame: Baseline to 192 weeks ] [ Designated as safety issue: No ]
  The percentage of participants achieving a plasma HIV-1 RNA decrease of >= 1.0 log10 copies/mL from baseline at Week 192 were summarized.
• Percentage of Participants With an HIV-1 RNA Decrease of >= 1.0 log10 Copies/mL From Baseline to Week 240. [ Time Frame: Baseline to 240 weeks ] [ Designated as safety issue: No ]
  The percentage of participants achieving a plasma HIV-1 RNA decrease of >= 1.0 log10 copies/mL from baseline at Week 240 were summarized.
• Percentage of Participants With HIV-1 RNA < 400 Copies/mL at Week 96. [ Time Frame: Week 96 ] [ Designated as safety issue: No ]
  The percentage of participants with plasma HIV-1 RNA < 400 copies/mL at Week 96 were summarized.
• Percentage of Participants With HIV-1 RNA < 400 Copies/mL at Week 144. [ Time Frame: Week 144 ] [ Designated as safety issue: No ]
  The percentage of participants with plasma HIV-1 RNA < 400 copies/mL at Week 144 were summarized.
• Percentage of Participants With HIV-1 RNA < 400 Copies/mL at Week 192. [ Time Frame: Week 192 ] [ Designated as safety issue: No ]
  The percentage of participants with plasma HIV-1 RNA < 400 copies/mL at Week 192 were summarized.
• Percentage of Participants With HIV-1 RNA < 400 Copies/mL at Week 240. [ Time Frame: Week 240 ] [ Designated as safety issue: No ]
  The percentage of participants with plasma HIV-1 RNA < 400 copies/mL at Week 240 were summarized.
• Percentage of Participants With HIV-1 RNA < 50 Copies/mL at Week 96. [ Time Frame: Week 96 ] [ Designated as safety issue: No ]
  The percentage of participants with plasma HIV-1 RNA < 50 copies/mL at Week 96 were summarized.
• Percentage of Participants With HIV-1 RNA < 50 Copies/mL at Week 144. [ Time Frame: Week 144 ] [ Designated as safety issue: No ]
  The percentage of participants with plasma HIV-1 RNA < 50 copies/mL at Week 144 were summarized.
• Percentage of Participants With HIV-1 RNA < 50 Copies/mL at Week 192. [ Time Frame: Week 192 ] [ Designated as safety issue: No ]
  The percentage of participants with plasma HIV-1 RNA < 50 copies/mL at Week 192 were summarized.
• Percentage of Participants With HIV-1 RNA < 50 Copies/mL at Week 240. [ Time Frame: Week 240 ] [ Designated as safety issue: No ]
  The percentage of participants with plasma HIV-1 RNA < 50 copies/mL at Week 240 were summarized.

The purpose of this study was to assess the safety and efficacy of tenofovir disoproxil fumarate (TDF) plus a genotype-guided optimized background regimen (OBR) compared to placebo plus OBR in the treatment of human immunodeficiency virus type 1 (HIV-1) infected antiretroviral treatment-experienced adolescents with plasma HIV-1 ribonucleic acid (RNA) levels greater than or equal to 1000 copies/mL.

This was a 48-week, randomized, double-blind, placebo-controlled, multicenter study of the safety and efficacy of tenofovir DF as part of an optimized antiretroviral regimen in HIV-1 infected adolescents (12 years to < 18 years of age) who were failing their current antiretroviral regimen and had HIV-1 RNA levels >= 1000 copies/mL at screening. Data from three consecutive 96-week study extensions (ongoing) have been used to evaluate the long-term efficacy, safety, and tolerability of open-label tenofovir DF as part of an antiviral regimen, providing data for up to 336 weeks of total drug exposure.

Pretreatment:

HIV-1 genotyping was performed as part of the screening assessments to assist in the construction of an OBR, defined as at least 3, but no more than 5 antiretroviral agents, not including tenofovir DF or placebo.

Randomized Phase:

Participants were randomized in a 1:1 ratio to receive either tenofovir DF + OBR or placebo + OBR. The majority of efficacy and safety assessments were performed at each clinic visit (Weeks 4, 8, 16, 24, 32, 40, and 48). At Week 24, participants who were adherent to study drug (in the opinion of the investigator), but did not demonstrate a >= 0.5 log10 copies/mL decrease from baseline in HIV-1 RNA, were considered to be nonresponders and were unblinded. Nonresponders randomized to the placebo group were given the option to continue on study and receive open-label tenofovir DF with an appropriate background regimen determined by the investigator. Nonresponders randomized to the tenofovir DF treatment group were discontinued from the study.

Extension Phases:

After completing 48 weeks of double-blind treatment with tenofovir DF or placebo, participants who had not reached 18 years of age, and who, in the opinion of the investigator, would derive clinical benefit from the use of open-label tenofovir DF, were given the option to continue (or initiate) treatment with open-label tenofovir DF in the first of three 96 week study extension periods. Nonresponders who received open-label tenofovir DF after Week 24 were also considered eligible for the first study extension if they met the above criteria at Week 48.

After completing the first 96 week study extension, participants who had not reached 18 years of age, and who had shown ongoing clinical benefit from tenofovir DF, were given the option to continue receiving open-label tenofovir DF for an additional 96 weeks or until tenofovir DF became commercially available in the country where the participants were enrolled, whichever occurred first.

After completing the second 96 week study extension, participants who had not reached 18 years of age, and who had shown ongoing clinical benefit from tenofovir DF, were given the option to continue receiving open-label tenofovir DF for an additional 96 weeks or until tenofovir DF became commercially available in the country where the participants were enrolled, whichever occurred first.

Presentation of data:

Participants who were randomized to placebo during the randomized phase of the study and then switched to open-label tenofovir DF had their baseline reset (defined as open-label baseline), and only outcome data collected after (on/after for AEs/concomitant medications) participants received their first dose of open-label tenofovir DF were included in this entry.

• Drug: Tenofovir DF
  Tenofovir DF 300-mg tablet, administered orally, daily + OBR
• Drug: Placebo
  Tenofovir DF Placebo administered orally, daily + OBR

• Experimental: OBR + Tenofovir DF
  Tenofovir DF administered orally, one tablet daily without regard to meals.
  Intervention: Drug: Tenofovir DF
• Placebo Comparator: OBR + Tenofovir DF Placebo
  Intervention: Drug: Placebo

Major Inclusion Criteria:

• Weight greater than or equal to 35 kg
• Documented laboratory diagnosis of HIV infection
• Plasma HIV-1 RNA greater than or equal to 1000 copies/mL
• Prior antiretroviral treatment experience with at least 2 antiretroviral drug classes
• Naive to tenofovir DF
• Absence of K65R mutation on genotypic testing

Exclusion Criteria:

• Patients requiring didanosine in background regimen
• Prior history of significant renal disease
• Prior history of significant bone disease