TILT: a randomized controlled trial of interruption of antiretroviral therapy with or without interleukin-2 in HIV-1 infected individuals

Clinical trials of antiretroviral treatment interruption in HIV-infected individuals

: Despite the benefits of antiretroviral therapy (ART) for people living with HIV, there has been a long-standing research interest in interrupting ART as a strategy to minimize adverse effects of ART as well as to test interventions aiming to achieve a degree of virological control without ART. We performed a systematic review of HIV clinical studies involving treatment interruption from 2000 to 2017 to describe the differences between treatment interruption in studies that contained and didn't contain an intervention. We assessed differences in monitoring strategies, threshold to restart ART, duration and adverse outcomes of treatment interruption, and factors aimed at minimizing transmission. We found that treatment interruption has been incorporated into 159 clinical studies since 2000 and is increasingly being included in trials to assess the efficacy of interventions to achieve sustained virological remission off ART. Great heterogeneity was noted in immunological, virological and clinical monitoring strategies, as well as in thresholds to recommence ART. Treatment interruption in recent intervention studies were more closely monitored, had more conservative thresholds to restart ART and had a shorter treatment interruption duration, compared with older treatment interruption studies that didn't include an intervention.

Soluble mediators of inflammation in HIV and their implications for therapeutics and vaccine development

From early in the HIV epidemic it was appreciated that many inflammatory markers such as neopterin and TNF-α were elevated in patients with AIDS. With the advent of modern technology able to measure a broad array of cytokines, we now know that from the earliest points of infection HIV induces a cytokine storm. This review will focus on how cytokines are disturbed in HIV infection and will explore potential therapeutic uses of cytokines. These factors can be used directly as therapy during HIV infection, either to suppress viral replication or prevent deleterious immune effects of infection, such as CD4+ T cell depletion. Cytokines also show great promise as adjuvants in the development of HIV vaccines, which would be critical for the eventual control of the epidemic.

Role of interleukin-2 in patients with HIV infection

Control of viral replication to below the level of quantification using combination antiretroviral therapy (ART) [cART] has led to a dramatic fall in mortality and morbidity from AIDS. However, despite the success of cART, it has become apparent that many patients do not achieve normalized CD4+ T-cell counts despite virological suppression to below the level of quantification (<50 copies/mL). Increasing data from cohort studies and limited data from clinical trials, such as the SMART study, have shown that higher CD4+ T-cell counts are associated with reductions in morbidity and mortality from both AIDS and serious non-AIDS (SNA) conditions, including cardiovascular disease. Enhancement of immune restoration over and above that achievable with ART alone, using a number of strategies including cytokine therapy, has been of interest for many years. The most studied cytokine in this setting is recombinant interleukin (IL)-2 (rIL-2). The purpose of this review is to describe the current status of rIL-2 as a therapeutic agent in the treatment of HIV-1 infection. The review focuses on the rationale underpinning the exploration of rIL-2 in HIV infection, summarizing the phase II and III findings of rIL-2 as an adjunctive therapy to ART and the phase II studies of rIL-2 as an antiretroviral-sparing agent. The phase II studies demonstrated the potential utility of continuous intravenous IL-2 and subsequently intermittent dosing with subcutaneous rIL-2 as a cytokine that could expand the CD4+ T-cell pool in HIV-1-infected patients without any significant detrimental effect on HIV viral load and with an acceptable adverse-effect profile. These data were utilized in designing the phase II studies of rIL-2 as an ART-sparing agent and, more importantly, the large phase III clinical endpoint studies of rIL-2 in HIV-1-infected adults, ESPRIT and SILCAAT. In the latter, subcutaneous rIL-2 was given intermittently (5 days of twice-daily dosing at 4.5-7.5 million international units per dose every 8 weeks) to HIV-1-infected adults receiving cART using an induction/maintenance strategy. Both studies explored the clinical benefit of intermittent subcutaneous rIL-2 with cART versus cART in HIV-infected adults with CD4+ T-cell counts > or = 300 cells/microL (ESPRIT study) and 50-299 cells/microL (SILCAAT study). Both studies showed that receipt of rIL-2 conferred no clinical benefit despite a significantly higher CD4+ T-cell count in the rIL-2 arms of both studies. Moreover, there was an excess of grade 4 clinical events in ESPRIT rIL-2 recipients. The results of the phase III clinical endpoint studies showed that rIL-2 has no place as a therapeutic agent in the treatment of HIV infection.

Immunotherapies in HIV-1 infection

PURPOSE OF REVIEW

The purpose of this review is to describe the current status of immunotherapies for the treatment of HIV-1 infection. This review is timely, as the results of the phase III clinical trials of recombinant interleukin-2 (rIL-2) as adjuncts to combination antiretroviral therapy are about to be released.

RECENT FINDINGS

For many years, the use of rIL-2 in HIV-infected individuals has been explored. Although the results of the clinical endpoint studies of rIL-2 are awaited, there are now further data for rIL-2 as a stand-alone therapy for the treatment of HIV. Maraviroc, a recently approved anti-HIV agent, is a small molecule antagonist of human chemokine receptor-5. The recent observation that maraviroc-treated patients achieved higher CD4 and CD8 T-cell counts compared with comparator regimens (without a chemokine receptor-5 antagonist) for equivalent viral load reductions has fueled interest in using these host-directed therapies to enhance immune restoration.

SUMMARY

This review summarizes the most recent clinical data for rIL-2 and reviews other immunotherapies in earlier development including cytokines rIL-7, rIL-15, rIL-21, new therapeutic vaccination approaches including infusion of overlapping HIV peptides and dendritic cell immunotherapy and novel agents including luteinizing hormone-releasing hormone analogues and vitamin D3-binding protein macrophage activating factor.

Inferiority of IL-2 alone versus IL-2 with HAART in maintaining CD4 T cell counts during HAART interruption: a randomized controlled trial

OBJECTIVE

To evaluate whether interleukin (IL)-2 in patients with chronic HIV infection can maintain CD4 T cell counts during 6 months of HAART interruption.

DESIGN

Prospective, randomized, controlled, open-label phase II noninferiority trial comparing IL-2 with HAART interruption or continuous HAART.

METHODS

Forty-one IL-2-experienced (three or more prior cycles) HIV-1-infected adults with CD4 cell count at least 500 cells/microl were randomized in the ratio 2: 1 to interrupted (I = 27) or continuous (C = 14) HAART for 6 months following an initial IL-2 cycle. Subsequent IL-2 cycles were triggered by CD4 T cell counts less than 90% of baseline. Immune, metabolic, and quality of life indices were compared (Mann-Whitney and Fisher's exact tests), defining noninferiority as a percentage difference (C- I) in treatment success (CD4 T cells > or =90% of baseline at 6 months) with a 95% confidence interval (CI) lower limit greater than -20%.

RESULTS

Demographic and immune parameters were similar between the groups at baseline. Median CD4 T cell count, HIV viral load, and treatment success differed significantly at 6 months (I: 866 cells/microl, 39,389 copies/ml, 48.1%; C: 1246 cells/microl, <50 copies/ml, 92.3%; P < or = 0.001). Group I was inferior to C (% difference = -44.2%; 95% CI: -64.2%, -11.2%; P = 0.013). Minor statistically significant differences in HgbA1c and energy level occurred at 6 months (I > C). Following HAART interruption, single cases of acute retroviral syndrome, secondary syphilis, non-Hodgkin's lymphoma, and Kaposi's sarcoma recurrence were observed.

CONCLUSION

IL-2 alone was inferior to IL-2 with HAART in maintaining baseline CD4 T cell counts. HAART interruption had a small impact on metabolic parameters and quality of life.