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Research Letter

Alpha interferon administration during structured interruptions of combination antiretroviral therapy in patients with chronic HIV-1 infection: INTERVAC ANRS 105 trial

Boué, Françoisa; Reynes, Jacquesb; Rouzioux, Christinec; Emilie, Dominiqued; Souala, Faouzie; Tubiana, Rollandf; Goujard, Cécileg; Lancar, Rémih; Costagliola, Dominiqueh,g

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doi: 10.1097/QAD.0b013e328340a1e7
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Abstract

Antiretroviral treatment interruption is usually associated with a viral rebound and a decline in the CD4 cell count. Some trials have suggested that successive short-structured treatment interruptions may attenuate the viral rebound and activate HIV-specific CD4 and CD8 T-cell-mediated immunity [1]. Interferon-α might be beneficial in this setting, because it stimulates infected cells to produce antiviral proteins and also stimulates the antiviral immune response mediated by natural killer cells and B and CD8+ T lymphocytes [2–15]. Here we examined whether interferon-α administration during structured antiretroviral treatment interruptions postpones the need for treatment resumption.

The multicenter, randomized, open-label, phase III study (NCT 00125814) involved HIV-infected adults who had been receiving the same continuous combination antiretroviral therapy (cART) regimen and whose viral load had been below 400 copies/ml for at least 6 months prior to inclusion. The CD4 cell count had to be above 350/μl and the CD4 nadir at least 100 cells/μl. Patients with chronic active hepatitis B or C were excluded. The study protocol was approved by the institutional review board of Bicêtre Hospital and the patients provided their written informed consent. Randomization was stratified according to participation in an immunovirological substudy.

In each arm, cART was interrupted for 4 weeks then resumed for 12 weeks, three times. Treatment was then suspended until the end of the trial (from week 48 to week 72) or until the patient reached a predefined endpoint and agreed to resume treatment. Patients randomized to STI-Inf received four subcutaneous injections of pegylated α-interferon (1.5 μg/kg) weekly from day 15 during each STI to day 8 after each cART resumption.

The primary endpoint was the proportion of patients who did not meet the criteria for antiretroviral treatment resumption by week 72. These criteria were viral load above 30 000 copies/ml in two consecutive samples 1 month apart, and/or a CD4 cell count below 350/μl (with a decline of at least 20% from baseline) in two consecutive samples 1 month apart.

It was expected that 60% of patients in the experimental arm (STI-Inf) and 40% of patients in the control arm (STI alone) would remain off treatment from week 48 to week 72. With 98 assessable patients in each arm, the study would have 80% power to detect a 20% difference in a bilateral log-rank test with a type 1 error of 0.05. Changes in the CD4 cell count, HIV-RNA, HIV-DNA [in peripheral blood mononuclear cell (PBMC)], and proliferation to p24 antigen were compared by using the Mann–Whitney test. Factors associated with the time-to-treatment resumption were identified by applying univariate and backward multivariate Cox proportional hazards models to the whole population and to the immunovirological substudy population. In the substudy, HIV-DNA levels in PBMC and lymphocyte proliferation to HIV-1 p24 were measured as previously described [16,17].

Between December 2001 and July 2003, 168 patients were randomized, 84 to STI alone and 84 to STI-Inf. Between week 0 and week 48, one patient in the STI-only arm and 6 patients in the STI-Inf arm left the study. One hundred and sixty-one patients were still eligible for analysis at week 48 (end of the STI phase) and 157 patients at week 72.

Patients in the two arms had similar baseline characteristics. The median CD4 cell count at inclusion was 688/μl, the median CD4 nadir was 323 cells/μl, and 98% of patients had HIV RNA below 400 copies/ml. The 60 patients enrolled in the substudy were not significantly different from the other patients.

The CD4 cell decline between week 0 and week 48 was significantly larger in the STI-Inf arm (-69/μl) than in the STI-only arm (+6/μl) (P = 0.0032). In contrast, the plasma HIV RNA rebound at the end of each treatment interruption was significantly smaller in the interferon arm (3715 vs. 56886 copies/ml, P < 0.001 at week 4; 884 vs. 17 296 copies/ml, P < 0.001 at week 20; 839 vs. 17 985 copies/ml, P < 0.001 at week 36). In both arms the viral rebound was significantly smaller at the end of the second and third interruptions than after the first interruption (P < 0.001). The proportions of patients with viral load below 400 copies/ml at the end of the first, second and third treatment interruptions in the STI-only and STI-Inf arms were, respectively, 7% vs. 35% (P < 0.001), 8% vs. 43% (P < 0.001), and 10% vs. 44% (P < 0.001). Just before the end of the third treatment period (week 48), only seven patients, all receiving two nucleoside reverse transcriptase inhibitors (NRTIs) + one non-nucleoside reverse transcriptase inhibitor (NNRTI), had viral load above 400 copies/ml (four in the STI-only arm and three in the STI-Inf arm). The virus could be amplified and sequenced in five of these patients, revealing NRTI resistance mutations in four patients (M184V in three cases, T215 in three cases, K70R in two cases) and NNRTI resistance mutations in three patients (K103N in two cases and G190A in one case).

At the end of the STI phase, 83 patients in the STI-only arm and 78 patients in the STI-Inf arm stopped treatment and were followed for 6 months. In the STI-only arm, 38 patients reached the criteria for treatment resumption (47% ± 6%), compared to 46 patients in the STI-Inf arm (56% ± 6%) (P = 0.16). Between week 48 and week 72, 39 patients resumed treatment, 17 in the STI-only arm and 22 in the STI-Inf arm. Twenty-five patients had viral load above 30 000 copies/ml (nine and 16 patients, respectively), three had CD4 cell count below 350/μl (one and two patients, respectively), and two patients (one in each arm) met both criteria; nine patients resumed treatment for other reasons (six and three patients, respectively).

Five serious adverse events occurred in the STI-only arm and nine in the STI-Inf arm; none were related to interferon. In the STI-Inf arm, two patients experienced grade 3 neutropenia and one experienced grade 2 hypertriglyceridemia.

The hazard ratio for the risk of meeting the criteria for treatment resumption was 1.43 per 1 log10 increase in pre-cART viral load [95% confidence interval (CI) 1.00–2.03]. As shown in Fig. 1(a), the hazard ratio was 1.13 (95% CI 0.57–2.23) for interferon-treated patients with a CD4 cell nadir above 323/μl, 1.40 (95% CI 0.73–2.69) for patients not treated with interferon whose CD4 cell nadir was below 323/μl, and 2.16 (95% CI 1.13–4.10) for interferon-treated patients with a CD4 cell nadir below 323/μl. Thus, interferon was deleterious in patients with a low CD4 cell nadir.

Fig. 1
Fig. 1:
(a) Kaplan–Meier plots of the time to reach the primary endpoint in the 168 patients, according to the CD4 cell count nadir and the treatment arm. (b) Kaplan–Meier plots of the time to reach the primary endpoint in the immunovirological substudy population (60 patients), according to the baseline HIV-DNA level and treatment arm.

In the substudy population the hazard ratio for the risk of reaching the treatment resumption criteria was 0.44 per log2 increase in the CD4 cell nadir (95% CI 0.22–0.89) and 0.94 per one-point increase in the proliferation index (95% CI 0.90–0.99). As shown in Fig. 1(b), by comparison with patients who did not receive interferon and whose HIV-DNA level at week 48 was below the median value of 480 copies/106 PBMC, the hazard ratio for treatment resumption was 1.08 (95% CI 0.37–3.16) among interferon-treated patients with HIV-DNA levels below 480 copies/106 PBMC, 0.67 (95% CI 0.19–2.32) among patients who were not treated with interferon and whose HIV-DNA level was above 480 copies/106 PBMC, and 4.89 (95% CI 1.75–13.68) in interferon-treated patients with HIV-DNA above 480 copies/106 PBMC. Thus, interferon was also deleterious in patients with high HIV-DNA levels.

The trial shows that interferon-α administration during structured antiretroviral treatment interruptions does not prolong the time-to-treatment resumption. We confirm that the CD4 cell nadir is predictive of treatment resumption, together with pre-cART viral load [6,18–20]. The PBMC HIV-DNA level and the anti-p24 proliferative response at baseline were also predictive of treatment resumption, again confirming the results of a previous study [6].

The safety of antiretroviral treatment interruption is a major concern. However, although this trial was not powered to detect significant differences in clinical events, we observed only two such events (cryptosporidiosis and pneumococcal pneumonia), in line with the results of previous interruption trials involving patients with similar CD4 cell counts [18–20].

Patients receiving NNRTIs represented 38% of our study population. The investigators were advised to stop NNRTIs 7 days before NRTIs, but we nonetheless observed seven cases of viral escape, associated with genotypic mutations in the five patients analyzed. This confirms that treatment interruption should not be attempted in patients on NNRTI-based therapy.

Interferon blunted the viral load rebound during the STI phase, but not after all treatments had been stopped. On the contrary, patients with a low CD4 cell nadir or a high HIV-DNA level who received interferon had a significantly higher risk of reaching a viral load above 30 000 copies/ml or a CD4 cell count below 350/μl, thus requiring treatment resumption.

Our results confirm that the viral rebound during STI correlates with specific anti-HIV immune responses, based on proliferation to p24. This response was not bolstered by STI in either treatment arm (data not shown), and was not enhanced by interferon therapy.

In conclusion, this trial shows that treatment interruption after STI is well tolerated in patients with high baseline CD4 cell counts, and that interferon-α administration during STI is not beneficial.

Acknowledgements

Authors' contributions: F.B., J.R. and D.C. designed the trial and analyzed the results. C.R. and D.E. coordinated the immunovirological study. R.L. did the data analysis. F.S., R.T. and C.G. participated to patient's recruitment.

We thank the members of the Data Safety Monitoring Board: Bernard Hirschel, Fabrice Carrat, Jean-Luc Pellegrin, and Vincent Calvez.

Pegylated α interferon was provided by Schering Plough, France. The French National Agency for Aids and Viral Hepatitis Research (ANRS) sponsored this trial.

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