Differential CD4 T-cell response in HIV-1-infected patients using protease inhibitor-based or nevirapine-based highly active antiretroviral therapy

Is immune recovery different depending on the use of integrase strand transfer inhibitor-, non-nucleoside reverse transcriptase- or boosted protease inhibitor-based regimens in antiretroviral-naive HIV-infected patients?

OBJECTIVES

To analyse whether integrase inhibitor (InSTI)-based regimens achieve better immunological recovery than NNRTI- or boosted PI (bPI)-based regimens as initial ART.

METHODS

In a retrospective analysis, we selected patients who initiated ART with two NRTIs plus an InSTI, an NNRTI or a bPI and maintained both the same 'third drug' and an HIV-RNA <50 copies/mL in ≥95% of determinations once undetectable viral load had been achieved. We compared CD4+ count, %CD4+ and CD4+/CD8+ ratio recovery over 2 years. Data were analysed using mixed-effects regression models for repeated measures.

RESULTS

Of the 836 patients included, 208, 481 and 147 initiated with InSTI, NNRTI and bPI, respectively. For CD4+, %CD4+ and CD4+/CD8+ two main slopes were identified: from month 0 to month 6, with the highest increments; and from month 6 to month 24, with smaller increases every semester. Although the patients on InSTI achieved undetectable viral load faster, for CD4+ and %CD4+ there were no differences in the slopes of change according to the third drug either for the first phase (P=0.137 and P=0.393, respectively) or from month 6 onwards (P=0.834 and P=0.159, respectively). The increase in CD4+/CD8+ was slightly higher for bPI compared with InSTI (difference of 0.0119, 95% CI 0.0020-0.0205; P=0.018), but clinically negligible. From month 6 onwards, no differences were found between treatment groups (P=0.176).

CONCLUSIONS

Immune restoration measured as CD4+ count, %CD4+ and CD4+/CD8+ increases was independent of the third antiretroviral drug class used when given with two NRTIs.

CD4:CD8 ratio comparison between cohorts of HIV-positive Asians and Caucasians upon commencement of antiretroviral therapy

BACKGROUND

In the era of effective antiretroviral treatment (ART) CD4:CD8 ratio is proposed as a potential marker for HIV-positive (HIV+) patients at increased risk for non-AIDS comorbidities. The current study aims to compare CD4:CD8 ratio between Asian and Caucasian HIV+ patients.

METHODS

HIV+ patients from the Australian HIV Observational Database (AHOD) and the TREAT Asia HIV Observational Database (TAHOD) meeting specific criteria were included. In these analyses Asian and Caucasian status were defined by cohort. Factors associated with a low CD4:CD8 ratio (cutoff <0.2) prior to ART commencement, and with achieving a normal CD4:CD8 ratio (>1) at 12 and 24 months post ART commencement were assessed using logistic regression.

RESULTS

There were 591 patients from AHOD and 2,620 patients from TAHOD who met the inclusion criteria. TAHOD patients had a significantly (P<0.001) lower odds of having a baseline (prior to ART initiation) CD4:CD8 ratio greater than 0.2. After 12 months of ART, AHOD patients were more than twice as likely to achieve a normal CD4:CD8 ratio compared to TAHOD patients (15% versus 6%). However, after adjustment for confounding factors there was no significant difference between cohorts in the odds of achieving a CD4:CD8 ratio >1 (P=0.475).

CONCLUSIONS

We found a significantly lower CD4:CD8 ratio prior to commencing ART in TAHOD compared to AHOD even after adjusting for confounders. However, after adjustment, there was no significant difference between the cohorts in odds of achieving normal ratio. Baseline CD4⁺ and CD8⁺ counts seem to be the main driver for this difference between these two populations.

Trends in CD4 cell count response to first-line antiretroviral treatment in HIV-positive patients from Asia, 2003-2013: TREAT Asia HIV Observational Database Low Intensity Transfer

Antiretroviral treatment (ART) guidelines have changed over the past decade, recommending earlier initiation and more tolerable regimens. The study objective was to examine the CD4 response to ART, depending on the year of ART initiation, in HIV-positive patients in the Asia-Pacific. We included HIV-positive adult patients who initiated ART between 2003 and 2013 in our regional cohort from eight urban referral centres in seven countries within Asia. We used mixed-effects linear regression models to evaluate differences in CD4 response by year of ART initiation during 36 months of follow-up, adjusted a priori for other covariates. Overall, 16,962 patients were included. Patients initiating in 2006-9 and 2010-13 had an estimated mean CD4 cell count increase of 8 and 15 cells/µl, respectively, at any given time during the 36-month follow-up, compared to those in 2003-5. The median CD4 cell count at ART initiation also increased from 96 cells/µl in 2003-5 to 173 cells/µl in 2010-13. Our results suggest that the CD4 response to ART is modestly higher for those initiating ART in more recent years. Moreover, fewer patients are presenting with lower absolute CD4 cell counts over time. This is likely to reduce their risk of opportunistic infections and future non-AIDS defining cancers.

Clinical predictors of immune reconstitution following combination antiretroviral therapy in patients from the Australian HIV Observational Database

Background

A small but significant number of patients do not achieve CD4 T-cell counts >500cells/µl despite years of suppressive cART. These patients remain at risk of AIDS and non-AIDS defining illnesses. The aim of this study was to identify clinical factors associated with CD4 T-cell recovery following long-term cART.

Methods

Patients with the following inclusion criteria were selected from the Australian HIV Observational Database (AHOD): cART as their first regimen initiated at CD4 T-cell count <500cells/µl, HIV RNA<500copies/ml after 6 months of cART and sustained for at least 12 months. The Cox proportional hazards model was used to identify determinants associated with time to achieve CD4 T-cell counts >500cells/µl and >200cells/µl.

Results

501 patients were eligible for inclusion from AHOD (n = 2853). The median (IQR) age and baseline CD4 T-cell counts were 39 (32–47) years and 236 (130–350) cells/µl, respectively. A major strength of this study is the long follow-up duration, median (IQR) = 6.5(3–10) years. Most patients (80%) achieved CD4 T-cell counts >500cells/µl, but in 8%, this took >5 years. Among the patients who failed to reach a CD4 T-cell count >500cells/µl, 16% received cART for >10 years. In a multivariate analysis, faster time to achieve a CD4 T-cell count >500cells/µl was associated with higher baseline CD4 T-cell counts (p<0.001), younger age (p = 0.019) and treatment initiation with a protease inhibitor (PI)-based regimen (vs. non-nucleoside reverse transcriptase inhibitor, NNRTI; p = 0.043). Factors associated with achieving CD4 T-cell counts >200cells/µl included higher baseline CD4 T-cell count (p<0.001), not having a prior AIDS-defining illness (p = 0.018) and higher baseline HIV RNA (p<0.001).

Conclusion

The time taken to achieve a CD4 T-cell count >500cells/µl despite long-term cART is prolonged in a subset of patients in AHOD. Starting cART early with a PI-based regimen (vs. NNRTI-based regimen) is associated with more rapid recovery of a CD4 T-cell count >500cells/µl.

Protease Inhibitors as Immunomodulatory Drugs for HIV Infection

More than 20 drugs from four therapeutic drug classes are widely available for the management of human immunodeficiency virus (HIV) infection, with promising drugs from two new drug classes expected to be approved by the US Food and Drug Administration (FDA) in mid-to-late 2007 (Table 1). When used in combination, these drugs can lead to durable and perhaps indefinite suppression of viral replication.

Impact of ethnicity and HIV type 1 subtype on response to first-line antiretroviral therapy

A distinct effectiveness of highly active antiretroviral therapy (HAART) in HIV-infected patients across ethnicities may reflect differences in drug adherence, host genetic factors, and/or predominant HIV subtypes. We investigated the immunologic outcome in 79 drug-naive HIV individuals living in Madrid, 39 of whom were African immigrants, who achieved and maintained undetectable viral load for up to 24 months following initiation of HAART. Overall, 90% of whites were infected with clade B viruses while 80% of Africans carried non-B subtypes. Gender, age, mean baseline viral load, and CD4 counts were comparable in both groups. The mean time to reach undetectable viremia did not differ significantly between groups. CD4 gains at 24 months following HAART initiation were also similar, although Africans showed higher CD4 gains than whites at month 12. In a multivariate analysis neither HIV subtype nor ethnicity was associated with different CD4 gains at any given time point, suggesting that reconstitution of CD4+ T cells under HAART is not influenced by ethnicity.

Efavirenz: a review

Efavirenz is a non-nucleoside reverse transcriptase inhibitor that in most treatment guidelines is recommended to be taken combined with two nucleoside analogue reverse transcriptase inhibitors, as a preferred first-line regimen for the treatment of HIV-1 infection. The antiretroviral efficacy of efavirenz-based combination regimens is good, as has been demonstrated in many clinical trials. Efavirenz has a long plasma half-life, which allows for once-daily dosing, but, as a consequence of this and the low genetic barrier, it is also prone to select for viral resistance when adherence to therapy is suboptimal. The most frequently encountered side effects are neuropsychiatric symptoms. These side effects are usually transient, but have been shown to persist for up to 2 years after initiation of therapy in some patients. This review outlines important and recent pharmacological and clinical data, which explain why efavirenz became a component of preferred treatment regimens today.

Effect of baseline- and treatment-related factors on immunologic recovery after initiation of antiretroviral therapy in HIV-1-positive subjects: results from ACTG 384

OBJECTIVE

To assess the effect of baseline- and treatment-related factors on immunologic recovery after initiation of antiretroviral therapy (ART).

METHODS

Nine hundred eighty antiretroviral-naive HIV-1+ subjects were randomized to start stavudine/didanosine or zidovudine/lamivudine with nelfinavir, efavirenz, or both nelfinavir and efavirenz.

RESULTS

Greater CD4 cell recovery was associated with age of 40 years or younger, female sex, higher baseline naive/memory CD4 cell ratio, higher baseline virus load (VL), and virologic suppression (VS). Most subjects who maintained an undetectable VL had a substantial increase in CD4 cell count, but 13% of the subjects did not, even after 3 years of VS. Persistent T-cell activation was associated with lower CD4 cell recovery, even in subjects who achieved VS. Initial treatment assignment did not affect total CD4 cell recovery, naive/memory CD4 cell reconstitution, or decline in T-cell activation. In addition to CD4 cell recovery, B-cell counts rose substantially after ART initiation.

CONCLUSIONS

In this large randomized trial, younger age, female sex, higher naive/memory CD4 cell ratio, higher baseline VL, and VS were associated with greater CD4 cell increase, whereas persistent T-cell activation was associated with impaired CD4 cell recovery after ART initiation. Initial treatment assignment did not affect CD4 cell reconstitution.

Targeting antiretroviral therapy: lessons from a longitudinal study of morbidity and treatment in relation to CD4 count in Thailand

The aim of the study was to quantify the incidence of illness and treatment behaviour in relation to CD4 count, age, and gender among a cohort of persons living with HIV/AIDS in Thailand. 464 participants with a CD4 count between 50 and 550 cells/mm3 were followed up for 12 months. Multiple Poisson regression was used to model the adjusted incidence rate ratio of illness and care seeking at different levels. The incidence of morbidity and treatment pattern were significantly different among participants with different CD4 count, age and gender. For example, morbidity incidence was significantly higher among participants with CD4 count of less than 200 cells/mm3, among female participants, and participants aged 35 years or over. Females made significantly higher use of hospital ambulatory care and private clinics than males and males made significantly more use of private pharmacies. The potential opportunity cost of not providing ART to these different groups can be estimated and used to inform further economic evaluation and policy decisions on whether to provide ART at all and which patient groups to prioritise.

Relationship between antiretrovirals used as part of a cART regimen and CD4 cell count increases in patients with suppressed viremia

BACKGROUND

It is unknown if the CD4 cell count response differs according to antiretroviral drugs used in combination antiretroviral therapy (cART) in patients with maximal virological suppression [viral load (VL) < 50 copies/ml].

OBJECTIVES

To compare the change in CD4 cell count over consecutive measurements with VL < 50 copies/ml at both time-points according to nucleoside backbones and other antiretrovirals used.

METHODS

Generalized linear models, accounting for multiple measurements within patients, were used to compare CD4 cell count changes after adjustment for antiretrovirals, time from starting cART, age, CD4 at first VL < 50 copies/ml, prior antiretroviral treatment, and change in CD4 cell count since starting cART.

RESULTS

We studied 28418 instances of VL < 50 copies/ml in 4041 patients. The mean annual change in CD4 cell count was +45.5/microl [95% confidence interval (CI) +39.4 to +51.6/microl). Comparing two drug nucleoside backbones, there was a lower annual change in CD4 cell count for zidovudine/lamivudine (n = 13038; -15.4/microl; P = 0.012) and for those on tenofovir (n = 1809; -27.3/microl; P = 0.029) compared to lamivudine/stavudine (n = 7339). Compared to the boosted-protease inhibitor regimen (n = 5915), use of an abacavir-based triple-nucleoside regimen was associated with a lower annual change in CD4 cell count (n = 2504 pairs; -26.1/microl; P = 0.011).

CONCLUSIONS

A nucleoside backbone of zidovudine/lamivudine or any tenofovir-based backbone was associated with significantly poorer increases in CD4 cell count compared to a nucleoside backbone of stavudine/lamivudine, as was an abacavir-based triple nucleoside regimen compared to a boosted protease inhibitor regimen. Long-term studies are needed to determine whether the differences in immunological response seen here translate into differences in the risk of clinical disease.

The effect of baseline CD4 cell count and HIV-1 viral load on the efficacy and safety of nevirapine or efavirenz-based first-line HAART

BACKGROUND

A substantial number of patients start their first-line antiretroviral therapy at an advanced stage of an HIV-1 infection. Potential differences between specific drug regimens in antiviral efficacy and safety in these patients are of major importance.

METHODS

A post-hoc analysis within the randomized controlled 2NN trial comparing efficacy between regimes containing nevirapine (NVP), efavirenz (EFV), or both, in addition to stavudine and lamivudine.

PRIMARY OUTCOME

risk of virologic failure in different strata of baseline CD4 T-lymphocyte counts and plasma HIV-1 RNA concentrations (pVL). Virologic failure: never reaching a pVL < 400 copies/ml, or a rebound to two consecutive values > 400 copies/ml.

RESULTS

The risk of virologic failure was increased at very low CD4 counts (< 25 x 10(6) cells/l) compared to CD4 counts > 200 x 10(6) cells/l [hazard ratio (HR), 1.28; 95% confidence interval (CI), 0.93-1.77]. The same was seen for a pVL > or = 100,000 copies/ml compared to a lower pVL (HR, 1.20; CI, 0.96-1.50). There were no statistically significant differences between NVP and EFV in risk of virologic failure within any of the CD4 or pVL strata, although EFV performed slightly better in the low CD4 stratum. The incidence of rash in the NVP group was significantly higher in female patients with higher CD4 cell counts, while adverse events in the EFV group were not associated with CD4 cell count.

CONCLUSIONS

Initial antiretroviral therapy including NVP or EFV is effective in patients with an advanced HIV-1 infection. A high baseline CD4 cell count is associated with the occurrence of rash in female patients using NVP.