Comparison of virologic, immunologic, and clinical response to five different initial protease inhibitor-containing and nevirapine-containing regimens

Comparison of Single and Boosted Protease Inhibitor Versus Nonnucleoside Reverse Transcriptase Inhibitor–Containing cART Regimens in Antiretroviral-Naïve Patients Starting cART After January 1, 2000

BACKGROUND

Few published studies have considered both the short- and long-term virologic or immunologic response to combination antiretroviral therapy (cART) and the impact of different cART strategies.

PURPOSE

To compare time to initial virologic (<500 copies/mL) or immunologic (>200/mm3 cell increase) response in antiretroviral-naïve patients starting either a single protease inhibitor (PI; n = 183), a ritonavir-boosted PI regimen (n = 197), or a nonnucleoside reverse transcriptase inhibitor (NNRTI)-based cART regimen (n = 447) after January 1, 2000, and the odds of lack of virologic or immunologic response at 3 years after starting cART.

METHOD

Cox proportional hazards models and logistic regression.

RESULTS

After adjustment, compared to patients taking an NNRTI-regimen, patients taking a single-PI regimen were significantly less likely to achieve a viral load (VL) <500 copies/mL (relative hazard [RH] 0.74, 95% CI 0.54-0.84, p = .0005); there was no difference between the boosted-PI regimen and the NNRTI regimen (p = .72). There were no differences between regimens in the risk of >200/mm3 CD4 cell increase after starting cART (p > .3). At 3 years after starting cART, patients taking a single-PI-based regimen were more likely to not have virologic suppression (<500 copies/mL; odds ratio [OR] 1.60, 95% CI 1.06-2.40, p = .024), while there were no differences in the odds of having an immunologic response (>200/mm3 increase; p > .15). This model was adjusted for CD4 and VL at starting cART, age, prior AIDS diagnosis, year of starting cART, and region of Europe.

CONCLUSION

Compared to patients starting an NNRTI-based regimen, patients starting a single-PI regimen were less likely to be virologically suppressed at 3 years after starting cART. These results should be interpreted with caution, because of the potential biases associated with observational studies. Ultimately, clinical outcomes, such as new AIDS diagnoses or deaths, will be the measure of efficacy of cART regimens, which requires the follow-up of a very large number of patients over many years.

Clinical audit: virological and immunological response to combination antiretroviral therapy in HIV patients at a Sydney sexual health clinic

AIM

Bigge Park Centre (BPC) is a sexual health clinic located in a socially disadvantaged area in Southwest Sydney. This served as a retrospective clinical audit, documenting patient demographics, identifying factors associated with virological, immunological and discordant responses, evaluating the centre's ability in HIV control and investigating changes in practice from 1996 to 2007.

METHOD

Data including age, gender, ethnicity, mode of transmission, hepatitis co-infection, prior acquired immune deficiency syndrome (AIDS)-defining-illness, HIV-1 RNA and CD4+cell counts of patients on combination antiretroviral therapy (CART) for treatment of HIV with at least 1-year follow up at the BPC were analysed. Results were compared with other cohorts in medical literature.

RESULTS

BPC manages HIV patients from diverse backgrounds. Sequential monotherapy was associated with poor virological control, lower CD4+cell recovery and discordant response. When patients who had sequential monotherapy were excluded, Caucasian race, high viral load at 1 month and triple-NRTI (nucleoside reverse transcriptase inhibitor) regimen were associated with lack of virological control. Lower baseline viral load and triple-NRTI regimen were associated with lower CD4+cell recovery. Lower baseline CD4+cell count and prior diagnosis of AIDS were associated with discordant response. Virological control and CD4+cell recovery achieved were comparable to that documented in medical literature. There was no significant change over time in terms of timing of CART initiation, attainment of immunological response or virological control since the late 1990 s.

CONCLUSION

HIV control achieved at the BPC was comparable to that reported in medical literature. Enhancement of strategies to promote screening and improve adherence as well as performance of HIV resistance assessment and avoidance of triple-NRTI therapy will likely improve patient care.

Cohort studies: to what extent can they inform treatment guidelines?

PURPOSE OF REVIEW

This review examines situations in which information from cohort studies has proved to be useful for the development of treatment guidelines.

RECENT FINDINGS

Although there are several reasons why randomized controlled trials (RCTs) are felt to provide the most robust evidence for treatment guidelines, they may suffer from insufficient duration of follow-up, inadequate power to consider differences in important adverse events and highly selected patient populations. Furthermore, as most RCTs are performed for licensing purposes, strategic treatment decisions often lack supportive evidence from RCTs. Although data from cohort studies may be used to complement information from RCTs, cohort studies themselves are susceptible to several biases (most notably confounding) which may limit their findings. However, in the HIV field, information from such studies has been influential in guiding decisions relating to when to start highly active antiretroviral therapy, what drugs to use in the initial highly active antiretroviral therapy regimen and when to switch highly active antiretroviral therapy should virological failure occur.

SUMMARY

Given the biases that may be present, caution should be exercised when interpreting findings from cohort studies, particularly if comparisons are made of treatment strategies that involve some element of patient or clinician choice.

Hepatotoxicity associated with long- versus short-course HIV-prophylactic nevirapine use: a systematic review and meta-analysis from the Research on Adverse Drug events And Reports (RADAR) project

BACKGROUND AND OBJECTIVE

The antiretroviral nevirapine can cause severe hepatotoxicity when used 'off-label' for preventing mother-to-child HIV transmission (PMTCT), newborn post-exposure prophylaxis and for pre- and post-exposure prophylaxis among non-HIV-infected individuals. We describe the incidence of hepatotoxicity with short- versus long-course nevirapine-containing regimens in these groups.

METHODS

We reviewed hepatotoxicity cases among non-HIV-infected individuals and HIV-infected pregnant women and their offspring receiving short- (or=5 days) nevirapine prophylaxis. Sources included adverse event reports from pharmaceutical manufacturers and the US FDA, reports from peer-reviewed journals/scientific meetings and the Research on Adverse Drug events And Reports (RADAR) project. Hepatotoxicity was scored using the AIDS Clinical Trial Group criteria.

RESULTS

Toxicity data for 8216 patients treated with nevirapine-containing regimens were reviewed. Among 402 non-HIV-infected individuals receiving short- (n=251) or long-course (n=151) nevirapine, rates of grade 1-2 hepatotoxicity were 1.99% versus 5.30%, respectively, and rates of grade 3-4 hepatotoxicity were 0.00% versus 13.25%, respectively (p<0.001 for both comparisons). Among 4740 HIV-infected pregnant women receiving short- (n=3031) versus long-course (n=1709) nevirapine, rates of grade 1-2 hepatotoxicity were 0.62% and 7.04%, respectively, and rates of grade 3-4 hepatotoxicity were 0.23% versus 4.39%, respectively (p<0.001 for both comparisons). The rates of grade 3-4 hepatotoxicity among 3074 neonates of nevirapine-exposed HIV-infected pregnant women were 0.8% for those receiving short-course (n=2801) versus 1.1% for those receiving long-course (n=273) therapy (p<0.72).

CONCLUSIONS

Therapy duration appears to significantly predict nevirapine hepatotoxicity. Short-course nevirapine for HIV prophylaxis is associated with fewer hepatotoxic reactions for non-HIV-infected individuals or pregnant HIV-infected women and their offspring, but administration of prophylactic nevirapine for >or=2 weeks appears to be associated with high rates of hepatotoxicity among non-HIV-infected individuals and HIV-infected pregnant mothers. When full highly active antiretroviral therapy (HAART) regimens are not available, single-dose nevirapine plus short-course nucleoside reverse transcriptase inhibitors to decrease the development of HIV viral resistance is an essential therapeutic option for PMTCT and these data support the safety of single-dose nevirapine in this setting.

Does short-term virologic failure translate to clinical events in antiretroviral-naïve patients initiating antiretroviral therapy in clinical practice?

OBJECTIVE

To determine whether differences in short-term virologic failure among commonly used antiretroviral therapy (ART) regimens translate to differences in clinical events in antiretroviral-naïve patients initiating ART.

DESIGN

Observational cohort study of patients initiating ART between January 2000 and December 2005.

SETTING

The Antiretroviral Therapy Cohort Collaboration (ART-CC) is a collaboration of 15 HIV cohort studies from Canada, Europe, and the United States.

STUDY PARTICIPANTS

A total of 13 546 antiretroviral-naïve HIV-positive patients initiating ART with efavirenz, nevirapine, lopinavir/ritonavir, nelfinavir, or abacavir as third drugs in combination with a zidovudine and lamivudine nucleoside reverse transcriptase inhibitor backbone.

MAIN OUTCOME MEASURES

Short-term (24-week) virologic failure (>500 copies/ml) and clinical events within 2 years of ART initiation (incident AIDS-defining event, death, and a composite measure of these two outcomes).

RESULTS

Compared with efavirenz as initial third drug, short-term virologic failure was more common with all other third drugs evaluated; nevirapine (adjusted odds ratio = 1.87, 95% confidence interval (CI) = 1.58-2.22), lopinavir/ritonavir (1.32, 95% CI = 1.12-1.57), nelfinavir (3.20, 95% CI = 2.74-3.74), and abacavir (2.13, 95% CI = 1.82-2.50). However, the rate of clinical events within 2 years of ART initiation appeared higher only with nevirapine (adjusted hazard ratio for composite outcome measure 1.27, 95% CI = 1.04-1.56) and abacavir (1.22, 95% CI = 1.00-1.48).

CONCLUSION

Among antiretroviral-naïve patients initiating therapy, between-ART regimen, differences in short-term virologic failure do not necessarily translate to differences in clinical outcomes. Our results should be interpreted with caution because of the possibility of residual confounding by indication.

Persistent low-level viraemia and virological failure in HIV-1-infected patients treated with highly active antiretroviral therapy

OBJECTIVE

To assess the prognostic significance of persistent low-level viraemia (PLV, defined as persistent plasma viral loads of 51-1000 HIV-1 RNA copies/mL for at least 3 months) in patients who had achieved viral suppression on antiretroviral therapy (ART).

METHODS

A retrospective cohort of HIV-infected patients who received ART, were followed-up for > or =12 months, made regular visits to the clinic during which blood tests were performed for an ultrasensitive HIV RNA assay every 3 months, and achieved viral loads <50 copies/mL were evaluated. Virological failure was defined as two consecutive viral load measurements >1000 copies/mL.

RESULTS

Of 362 patients, 78 (27.5%) experienced PLV. The demographics of patients with and without PLV were similar. PLV occurred at a mean (+/-standard deviation) of 22.6+/-16.9 months after ART initiation and lasted for 6.4+/-3.4 months. During a median follow-up of 29.5 months, patients with PLV had a higher rate of virological failure (39.7% vs 9.2%; P < 0.001). The median time to failure was 68.4 months [95% confidence interval (CI) 37.0-99.7] for patients with PLV and >72 months for patients without PLV (log rank test, P < 0.001). By Cox regression, patients with PLV had a greater risk of virological failure [hazard ratio (HR) 3.8; 95% CI 2.2-6.4; P < 0.001]. Among patients with PLV, a PLV of >400 copies/mL (HR 3.3; 95% CI 1.5-7.1; P = 0.003) and a history of ART (HR 2.4; 95% CI 1.0-5.7; P = 0.042) predicted virological failure.

CONCLUSIONS

PLV is associated with virological failure. Patients with a PLV >400 copies/mL and a history of ART experience are more likely to experience virological failure. Patients with PLV should be considered for treatment optimization and interventional studies.

Predictors of antiretroviral treatment failure in an urban HIV clinic

BACKGROUND

Predictors of antiretroviral treatment (ART) failure are not well characterized for heterogeneous clinic populations.

METHODS

A retrospective analysis was conducted of HIV-infected patients followed in an urban HIV clinic with an HIV RNA measurement < or =400 copies/mL on ART between January 1, 2003, and December 31, 2004. The primary endpoint was treatment failure, defined as virologic failure (> or =1 HIV RNA measurement >400 copies/mL), unsanctioned stopping of ART, or loss to follow-up. Prior ART adherence and other baseline patient characteristics, determined at the time of the first suppressed HIV RNA load on or after January 1, 2003, were extracted from the electronic health record (EHR). Predictors of failure were assessed using proportional hazards modeling.

RESULTS

Of 829 patients in the clinic, 614 had at least 1 HIV RNA measurement < or =400 copies/mL during the study period. Of these, 167 (27.2%) experienced treatment failure. Baseline characteristics associated with treatment failure in the multivariate model were: poor adherence (hazard ratio [HR] = 3.44; 95% confidence interval [CI]: 2.34 to 5.05), absolute neutrophil count <1000/mm (HR = 2.90, 95% CI: 1.26 to 6.69), not suppressed on January 1, 2003 (HR = 2.69, 95% CI: 1.78 to 4.07) or <12 months of suppression (HR = 1.64, 95% CI: 1.10 to 2.45), CD4 count <200 cells/mm (HR = 1.90, 95% CI: 1.31 to 2.76), nucleoside-only regimen (HR = 1.75, 95% CI: 1.08 to 2.82), prior virologic failure (HR = 1.70, 95% CI: 1.22 to 2.39) and > or =1 missed visit in the prior year (HR = 1.56, 95% CI: 1.13 to 2.16).

CONCLUSIONS

More than one quarter of patients in a heterogeneous clinic population had treatment failure over a 2-year period. Prior ART adherence and other EHR data readily identify patient characteristics that could trigger specific interventions to improve ART outcomes.

The impact of initial highly active antiretroviral therapy on future treatment sequences in HIV infection

OBJECTIVES

To determine whether the initial use of non-nucleoside reverse transcriptase inhibitors (NNRTI) or protease inhibitors (PI) differentially influences subsequent HIV therapy.

DESIGN

A cohort study using a prospective clinical database in a university-based HIV clinic.

SUBJECTS

A total of 440 HIV-seropositive patients, naive or nucleoside experienced, initiating therapy with either an NNRTI or PI between January 1998 and July 2003 and followed to December 2003.

MAIN OUTCOME MEASURES

Time until stopping the first regimen and until exposure to all antiretroviral classes (excluding tenofovir and enfuvirtide) according to the type of initial regimen.

RESULTS

A total of 291 subjects initiated HAART with PI and 149 with NNRTI; median follow-up 3.1 and 2.3 years, respectively. Subjects starting NNRTI remained on their initial regimens longer (median time to change 2.1 versus 1.6 years; log rank P = 0.03). Overall, subjects initiating NNRTI-based regimens were less likely to alter their therapy. Previous nucleoside exposure was an important predictor of treatment modification. Subjects initiating NNRTI-based HAART were also less likely to experience virological failure than those initiating PI-based HAART. Individuals starting with NNRTI were exposed to fewer regimens (15 versus 25% received three or fewer regimens), and showed a trend towards lower rates of three-class exposure (7 versus 12%).

CONCLUSION

There is a high rate of treatment modification among patients initiating HAART. The initial use of NNRTI-based HAART was associated with more durable treatment and lower rates of virological failure, which may translate into a reduced need for multiple salvage therapies.

Serious Adverse Cutaneous and Hepatic Toxicities Associated With Nevirapine Use by Non???HIV-Infected Individuals

BACKGROUND

Nevirapine is a nonnucleoside reverse transcriptase antiretroviral agent. Among HIV-infected individuals, rare instances (<1%) of serious cutaneous and hepatic toxicity have been reported. Because of its favorable pharmacokinetic profile, non-HIV-infected individuals have received nevirapine-containing postexposure prophylaxis (PEP).

OBJECTIVE

To describe the clinical features of cutaneous and hepatic toxicity that occurred when nevirapine was administered to non-HIV-infected individuals.

METHODS

Reports of nevirapine-associated cutaneous or hepatic toxicity occurring among non-HIV-infected individuals were obtained from the US Food and Drug Administration's adverse event reporting system, the pharmaceutic manufacturer, occupational health programs in Chicago, physicians, and case reports. The Eastern Cooperative Oncology Group (ECOG) scoring system was used to grade toxicity.

RESULTS

Twelve non-HIV-infected individuals developed severe cutaneous toxicity, including 3 with Stevens-Johnson syndrome, after 7 to 12 days of nevirapine-containing PEP regimens. Thirty non-HIV-infected individuals developed hepatotoxicity after 8 to 35 days of single-agent nevirapine (n = 8) or a nevirapine-containing PEP regimen (n = 22). Findings included ECOG grade 3 or 4 hepatotoxicity (n = 14), fevers (n = 11), skin rashes (n = 8), eosinophilia (n = 6), and fulminant hepatic necrosis requiring an orthotopic liver transplant (n = 1). Rates of severe hepatotoxicity (grade 3 or 4) in non-HIV-infected individuals ranged from 10% (4/41) to 62% (5/8). Liver biopsy material from 2 individuals was consistent with a hypersensitivity syndrome.

CONCLUSIONS

Serious hepatic and cutaneous toxicities can occur in non-HIV-infected individuals who receive short-term nevirapine therapy. The rate of severe hepatotoxicity appears to be greater in non-HIV-infected individuals than in HIV-infected persons and may be associated with higher CD4 counts. The use of PEP regimens containing nevirapine should be discouraged.

Provider bias in the selection of non-nucleoside reverse transcriptase inhibitor and protease inhibitor-based highly active antiretroviral therapy and HIV treatment outcomes in observational studies

OBJECTIVE

To compare the characteristics of patients prescribed non-nucleoside reverse transcriptase inhibitors (NNRTI) and protease inhibitors (PI), and evaluate treatment outcomes in a setting in which nevirapine has been preferentially recommended since 1998.

METHODS

A population-based analysis of antiretroviral-naive adults who started highly active antiretroviral therapy (HAART) between 1 August 1996 and 31 July 2000, and who were followed until 31 March 2002. We compared baseline characteristics, and evaluated virological responses and mortality.

RESULTS

Overall, 439 patients (28.8%) started HAART with NNRTI (94.1% used nevirapine), 100 (6.6%) used a double PI, and 983 (64.6%) used a single PI-based regimen. Substantial differences were observed between the baseline clinical characteristics of these populations. In adjusted analyses, in comparison with single PI therapy, only the use of NNRTI was associated with more rapid HIV-RNA suppression [relative hazard (RH) 1.42; 95% confidence interval (CI) 1.22-1.65; P < 0.001]. A total of 204 deaths were identified in the study population [42 (9.6%) NNRTI; 11 (11%) double PI; 151 (15.4%) single PI, respectively]. In adjusted analysis, NNRTI (RH 1.01; 95% CI 0.71-1.45) and double PI-based HAART (RH 0.74; 95% CI 0.40-1.39) had similar mortality rates to the single PI reference category.

CONCLUSION

NNRTI use was associated with more rapid virological suppression, whereas similar rates of rebound and mortality were found. Nevertheless, major baseline differences existed between patients prescribed the various initial regimens. As such, it is likely that similar selection factors may explain why our findings contrast with several non-randomized studies showing worse clinical outcomes of patients prescribed nevirapine.

Primary nelfinavir (NFV)-associated resistance mutations during a follow-up period of 108 weeks in protease inhibitor naïve patients treated with NFV-containing regimens in an HIV clinic cohort

BACKGROUND

Nelfinavir (NFV) is a widely prescribed HIV-1 specific protease inhibitor (PI). However, there are only a few reports that have described the long-term effects of NFV-containing regimens, especially with regard to the emergence of drug resistance in inner-city clinics.

OBJECTIVES

The aim of this study was to investigate the clinical and virologic responses to treatment with NFV-containing regimens for up to 108 weeks and determine the timing and rate of emergence of primary NFV-resistance associated mutations in daily clinical practice.

STUDY DESIGN

A cohort study in an inner-city clinic. Our study included 51 consecutive patients who were PI-nai;ve and commenced therapy in February 1997 through April 1999.

RESULTS AND CONCLUSIONS

The proportions of patients who continued the same therapeutic regimen and showed virologic success (viral load <400 copies/ml) up to 108 weeks were 78 and 63%, respectively, based on intent-to-treat analysis. Among patients with a viral load persistently >400 copies/ml at week 12 (n=30), 11 developed primary NFV-resistance associated mutations by 108 weeks (stratified log-rank test; P<0.05). The Cox proportional hazard model showed that prior use of reverse transcriptase inhibitors (n=22) (relative hazard (RH); 2.10, 95% CI; 0.67-6.62), prior AIDS diagnosis (n=6) (RH; 1.70, 95% CI; 0.37-7.77), CD4 < 200/microl at baseline (n=19) (RH; 2.48, 95% CI; 0.78-7.81) and viral load >30,000 copies/ml at baseline (n=21) (RH; 2.10, 95% CI; 0.67-6.62) were not independent predictors of the NFV-resistance, although some tendency was noted. In total, 77% of the patients continued NFV-containing treatment without the NFV-resistance for 108 weeks. The viral load at week 12 could be used as a predictor of treatment success in our cohort study.

[Diarrhea and HIV infection]

The development of Highly Active Antiretroviral Therapies and of protease inhibitors in particular has permitted in the last ten years to dramatically improve the viral replication in HIV infected patients but the incidence of side effects and of diarrhoea in particular remains high. In general practice, the occurrence of diarrhoea should systematically lead to eliminate an infectious ætiology of diarrhoea. Many studies have demonstrated that diarrhoea under protease inhibitors and nelfinavir in particular are of a low grade severity, occurring usually at the onset of therapy and are responsible for discontinuation of treatment in less than 2% of cases. The medium term follow up of patients cohorts demonstrates the lack of impact of diarrhoea on the antiretroviral efficacy of protease inhibitors. Nevertheless, coexisting diarrhoea is a factor of poor quality of life. This should lead to propose to patients several simple therapies, including dietetic rules, in order to limit the incidence of diarrhoea and to improve its consequences on the quality of life of patients.

Virologic and Immunologic Response to Highly Active Antiretroviral Therapy

Highly active antiretroviral therapy (HAART) delays clinical progression to AIDS by suppressing viral replication, allowing the immune system to reconstitute. These virologic and immunologic consequences do not occur uniformly among HAART users; markers of HIV disease stage at the time of HAART initiation are critical determinants of the progression while under HAART. In this paper, we review studies describing the heterogeneous virologic and immunologic progression following the initiation of HAART, and update findings obtained in the Multicenter AIDS Cohort Study that show that CD4 cell count and history of antiretroviral therapy at the time of initiation are independent determinants of response.