Development of HIV with drug resistance after CD4 cell count-guided structured treatment interruptions in patients treated with highly active antiretroviral therapy after dual-nucleoside analogue treatment. Structured antiretroviral treatment interruptions in chronically HIV-1-infected subjects. HIV dynamics and T-cell immunity after three structured treatment interruptions in chronic HIV-1 infection. Structured treatment interruption in chronically HIV-1 infected patients after long-term viral suppression. All4You! A randomized trial of an HIV, other STDs, and pregnancy prevention intervention for alternative school students. The virological and immunological consequences of structured treatment interruptions in chronic HIV-1 infection. A prospective, randomized trial of structured treatment interruption for patients with chronic HIV type 1 infection. Stimulation of HIV-specific cellular immunity by structured treatment interruption fails to enhance viral control in chronic HIV infection. Selection of drug-resistant HIV-1 mutants in response to repeated structured treatment interruptions.
For patients with human immunodeficiency virus (HIV) infection, structured treatment interruption (STI) is an attractive alternative strategy to continuous treatment, particularly in resource-restrained settings, because it reduces both side effects and costs. One major concern, however, is the development of resistance to antiretroviral drugs that can occur during multiple cycles of starting and stopping therapy.
                HIV genotypic drug resistance was investigated in 20 HIV-infected Thai patients treated with highly active antiretroviral therapy (HAART) and CD4 cell count-guided STI after dual nucleoside reverse-transcriptase inhibitor (NRTI) treatment. Resistance was tested at the time of the switch from dual-NRTI treatment to HAART and when HAART was stopped during the last interruption.
                After STI, one major drug-resistance mutation occurred (T215Y), and, in the 4 samples with preexisting major mutations (D67N [n=2], K70R [n=2], T215Y [n=2], and T215I [n=1]), the mutations disappeared. All mutations in the HIV protease gene were minor mutations already present, in most cases, before STI was started, and their frequency was not increased through STI, whereas the frequency of reverse-transcriptase gene mutations significantly decreased after the interruptions. After the 48-week study period, no patients had virological failure. Long-term follow-up (108 weeks) showed 1 case of virological failure in the STI arm and 1 in the continuous arm. No virological failure was seen in patients with major mutations.
                Major HIV drug-resistance mutations were not induced through CD4 cell count-guided treatment interruptions in HIV-infected patients successfully treated with HAART after dual-NRTI therapy. The risks and benefits of structured treatment interruption (STI) in HIV-1-infected subjects are not fully understood. A pilot study was performed to compare STI with continuous highly active antiretroviral therapy (HAART) in chronic HIV-1-infected subjects with HIV-1 plasma RNA levels (VL) <400 copies per ml and CD4(+) T cells >400 per microl. CD4(+) T cells, VL, HIV-1-specific neutralizing antibodies, and IFN-gamma-producing HIV-1-specific CD8(+) and CD4(+) T cells were measured in all subjects. STIs of 1-month duration separated by 1 month of HAART, before a final 3-month STI, resulted in augmented CD8(+) T cell responses in all eight STI subjects (P = 0.003), maintained while on HAART up to 22 weeks after STI, and augmented neutralization titers to autologous HIV-1 isolate in one of eight subjects. However, significant decline of CD4(+) T cell count from pre-STI level, and VL rebound to pre-HAART baseline, occurred during STI (P = 0.001 and 0.34, respectively). CD4(+) T cell counts were regained on return to HAART. Control subjects (n = 4) maintained VL <400 copies per ml and stable CD4(+) T cell counts, and showed no enhancement of antiviral CD8(+) T cell responses. Despite increases in antiviral immunity, no control of VL was observed. Future studies of STI should proceed with caution. To evaluate whether controlled re-exposures to autologous HIV-1 could boost HIV-specific immunity and limit virus replication in patients with chronic HIV-1 infection.
                Subjects with at least 2 years virus suppression during antiretroviral therapy and a CD4 : CD8 ratio > 1 were randomly assigned to interrupt highly active antiretroviral treatment (HAART) three times (n = 12) or to continue their previous HAART (n = 14).
                In 10/12 interrupter patients a rebound of HIV-1 RNA was detected in all three structured treatment interruptions (STI). Plasma virus doubling time was shorter during the first STI than in the second and third STI, corresponding to an average 13% reduction in viral basic reproductive rate. However, the mean time before plasma viral load rose to > 50 copies/ml was significantly shorter in the second and third STI. The average frequency of HIV-specific CD8 T cells in the interrupter patients at the end of the third STI cycle was significantly higher compared with the baseline and the end of the first STI. A substantial increase in HIV-specific CD8 T cell frequencies was found in four interrupter patients, whereas there were no changes in all 14 non-interrupter individuals. A weak p24-specific T helper response developed in 5/12 interrupter patients compared with no response in non-interruptors, but these responses were transient and disappeared rapidly.
                The increase in the control of viral replication, and positive effects of STI on immune responses in this population should encourage the further development of HIV-specific immune-based therapeutic strategies. To investigate the virological and immunological impact of a structured treatment interruption (STI) in a cohort of HIV-1 chronically infected patients with a further long-lasting effective virus suppression.
                Twelve HIV-1 chronically infected adults who had maintained viral suppression (< 20 copies/ml) for more than 2 years, as well as a CD4:CD8 ratio > 1 for a median time of 22 months, were included in the study. Participants interrupted their antiretroviral treatment during a maximum period of 30 days or until a viral load rebound > 3000 copies/ml was detected. The same prior antiretroviral regimen was resumed after STI. Kinetics of plasma viral rebound was evaluated every 2 days during the treatment interruption period. Flow cytometry and cell proliferation assays were performed before and after STI. Genotypic resistance was assessed at the time of treatment resumption.
                No adverse events occurred during the interruption period. In two patients no viral rebound was detected after 30 days of treatment interruption. In the remaining 10 patients, viral load became detectable (> 20 copies/ml) at a median time of 14 days after treatment interruption. Afterwards, viral load increased exponentially with a mean t1/2 of 1.6 days. Treatment was successfully resumed in all patients. No resistance-conferring mutations associated with the pre-interruption antiretroviral regimen were detected. The percentage of CD4 and CD8 lymphocytes did not vary during the STI period; however, the level of expression of T-cell activation antigen CD38 on CD8 T cells increased significantly in response to viral rebound. Four patients gained T-helper cell responses to recall antigens (tuberculin and tetanus toxoid), two of who developed an HIV-specific response to p24.
                STI in chronically HIV-1-infected patients is not associated with reductions in CD4 T lymphocytes or to clinical complications in this group of patients after 2 years of effective plasma viral suppression. Viral load rebounds in most but not all patients, without evidence of selection of resistance-conferring mutations. Thereafter, viraemia can be effectively controlled by antiretroviral agent reintroduction. HIV-specific T-helper cell responses may be achieved after one cycle of treatment interruption suggesting some degree of immune-stimulation. These data do not discard consecutive cycles of STI as a therapeutic strategy to boost HIV-specific immunity in order to maintain viral replication under effective control. This study evaluated All4You!, a theoretically based curriculum designed to reduce sexual risk behaviors associated with HIV, other STDs, and unintended pregnancy among students in alternative schools. The study featured a randomized controlled trial involving 24 community day schools in northern California. A cohort of 988 students was assessed four times during an 18-month period using a self report questionnaire. At the 6-month follow-up, the intervention reduced the frequency of intercourse without a condom during the previous 3 months, the frequency of intercourse without a condom with steady partners, and the number of times students reported having intercourse in the previous 3 months. It also increased condom use at last intercourse. These behavioral effects were no longer statistically significant at the 12- and 18-month follow-ups. The All4You! intervention was effective in reducing selected sexual risk behaviors among students in alternative school settings; however, the effects were modest and short term. Some individuals with chronic HIV-1 infection have discontinued their drug therapy with consequent plasma virus rebound. In a small number of patients, a delayed or absent rebound in plasma virus load has been noted after drug cessation, apparently associated with prior drug interruptions and autologous boosting of HIV-1 specific immune responses. We hypothesized that cyclic structured treatment interruptions structured treatment interruptions (STI) could augment HIV-1 specific immune responses in chronic HIV-1 infection, which might help to control HIV-1 replication off therapy.
                We initiated an STI pilot study in 10 antiretroviral treatment-naive HIV-1 chronically infected subjects with baseline CD4 T-cell counts > 500 x 10(6) cells/l and plasma viral load > 5000 copies/ml who received highly active antiretroviral therapy (HAART) for 1 year with good response (plasma viral load < 20 copies/ml for at least 32 weeks). Three cycles of HAART interruption were performed.
                In all of the patients viral load rebounded, but doubling times increased significantly between the first and third stops (P = 0.008), and by the third stop, six out of nine subjects had a virological set-point after a median 12 months off therapy that was lower than baseline before starting HAART (ranging from 0.6 log(10) to 1.3 log(10) lower than baseline) and in four it remained stable below 5000 copies/ml. Those subjects who controlled viral replication developed significantly stronger HIV-1 specific cellular immune responses than subjects lacking spontaneous decline (P < 0.05). During viral rebounds no genotypic or phenotypic changes conferring resistance to reverse trancriptase inhibitors or protease inhibitors was detected, but mean absolute CD4 T-cell counts declined significantly, although never below 450 x 10(6)/l and the mean value at 12 months off therapy was significantly higher than the pre-treatment level (P = 0.004).
                Our findings suggest that STI in chronic HIV-1 infection might augment HIV-1-specific cellular immune responses associated with a spontaneous and sustained drop in plasma viral load in some subjects but at the potential cost of lower CD4 T-cell counts. Structured treatment interruption was evaluated in 74 patients who had been pretreated with antiretrovirals, consisting of 2 nucleoside reverse-transcriptase inhibitors (NRTIs) for 1 year followed by 3 years of highly active antiretroviral therapy containing a protease inhibitor.
                Patients with a CD4 cell count of > or =350 cells/microL and a plasma viral load of <50 copies/mL were randomized to 3 therapy arms: (1) continuous therapy, (2) CD4 cell count-guided theory, and (3) week-on/week-off (WOWO) therapy. The efficacy and safety of structured treatment interruption and antiretroviral use were evaluated in human immunodeficiency type 1 (HIV-1)-infected patients. The study end points were percentage of patients who developed AIDS or who died and a CD4 cell count of > or =350 cells/microL. Intergroup differences were analyzed using analysis of variance and Kruskal-Wallis tests.
                Baseline characteristics at the start of the structured treatment interruption were similar. At week 48, no patient had died, and 1 patient in the WOWO group had an AIDS-defining condition. The proportions of patients with a CD4 cell count of > or =350 cells/microL were 100%, 87%, and 96% in treatment arms 1, 2, and 3, respectively. The percentages of weeks of antiretroviral use were 100%, 41.1%, and 69.8% in arms 1, 2, and 3, respectively. The adverse events were not significantly different among arms (P=.27). Thirty-one percent of patients in the WOWO group experienced virological failure.
                WOWO therapy maintained a CD4 cell count of > or =350 cells/microL in almost all patients but was associated with high virological failures rates (possibly resulting from previous dual-NRTI therapy), indicating that this strategy is less useful. Receipt of CD4 cell count-guided therapy resulted in comparable clinical outcomes to continuous therapy and may save antiretroviral-associated costs, but this needs to be confirmed by a larger trial. Potent antiretroviral therapy (ART) suppresses HIV-1 viral replication and results in decreased morbidity and mortality. However, prolonged treatment is associated with drug-induced toxicity, emergence of drug-resistant viral strains, and financial constraints. Structured therapeutic interruptions (STIs) have been proposed as a strategy that could boost HIV-specific immunity, through controlled exposure to autologous virus over limited time periods, and subsequently control viral replication in the absence of ART. Here, we analyzed the impact of repeated STIs on virological and immunological parameters in a large prospective STI study. We show that: (i) the plateau virus load (VL) reached after STIs correlated with pretreatment VL, the amount of viral recrudescence during the treatment interruptions, and the off-treatment viral rebound rate; (ii) the magnitude and the breadth of the HIV-specific CD8(+) T lymphocyte response, despite marked interpatient variability, increased overall with STI. However, the quantity and quality of the post-STI response was comparable to the response observed before any therapy; (iii) individuals with strong and broad HIV-specific CD8(+) T lymphocyte responses at baseline retained these characteristics during and after STI; (iv) the increase in HIV-specific CD8(+) T lymphocyte frequencies induced by STI was not correlated with decreased viral set point after STI; and (v) HIV-specific CD4(+) T lymphocyte responses increased with STI, but were subsequently maintained only in patients with low pretreatment and plateau VLs. Overall, these data indicate that STI-induced quantitative boosting of HIV-specific cellular immunity was not associated with substantial change in viral replication and that STI was largely restoring pretherapy CD8(+) T cell responses in patients with established infection. A new HIV-1 treatment strategy based on repeated structured treatment interruptions (STI) is currently being evaluated in clinical trials to determine whether immune cell-mediated control of viral replication can be stimulated by intermittent periods of viral replication. The potential for selection of drug-resistant quasi-species remains a major concern of such a treatment strategy.
                Plasma and peripheral blood lymphocyte (PBL) samples from 12 patients who had three consecutive STIs were studied. Genotypic analysis was based on population and clonal sequencing. Drug susceptibility and their corresponding replication capacities were evaluated by a single-cycle growth assay.
                Consistent with a loss of phenotypic susceptibility to lamivudine, the M184V mutation was detected by genotypic analysis (direct and clonal sequencing) in plasma samples collected from two patients at the end of the second or third STI. Longitudinal analysis of patient samples revealed a step-wise increase in the M184V mutation in each patient virus population over successive STIs, despite the lower replicative capacity associated with this mutation in the absence of antiviral agents.
                Drug-resistant virus can rise to high frequencies in chronically HIV-1 infected individuals during consecutive STIs. Evolution of resistance is likely to be more important in patients with prior suboptimal therapies, particularly when few mutations are required for resistance. Maximum care should be taken in designing STI protocols that minimize development of drug-resistant mutations that may lead to treatment failure. Thus, drug-resistance testing may be useful before restarting treatment during STI studies.
Timed-cycle STI have not been proven to be safe in the short term. Although CD4-guided STI strategy has reported favorable outcomes in the short term, the long-term safety, efficacy and tolerability of this strategy has not been fully investigated. Based on the studies we reviewed, the evidence to support the use of timed-cycle STI and CD4-guided STI cycles as a standard of care in the management of chronic suppressed HIV infection is inconclusive.