Lopinavir/Ritonavir Plus Nevirapine as a Nucleoside-Sparing Approach in Antiretroviral-Experienced Patients (NEKA Study)

Rilpivirine plus cobicistat-boosted darunavir as a two-drug switch regimen in HIV-infected, virologically suppressed subjects on steady standard three-drug therapy: a randomized, controlled, non-inferiority trial (PROBE 2)

BACKGROUND

We explored the combination of rilpivirine plus cobicistat-boosted darunavir [a two-drug regimen (2DR)] when switching from standard triple combined ART.

METHODS

In this randomized, open-label, non-inferiority trial, participants had an HIV-RNA <50 copies/mL on a stable (>6 months) three-drug regimen. The primary endpoint was proportion with HIV-RNA <50 copies/mL at Week 24 (snapshot algorithm), with a -12% non-inferiority margin. ClinicalTrials.gov: NCT04064632.

RESULTS

One hundred and sixty patients were allocated (1:1) to 2DR or to continue current ART (CAR). At Week 24, 72 (90.0%) of participants with 2DR and 75 (93.8%) with CAR maintained HIV-RNA <50 copies/mL [difference -3.75% (95% CI = -11.63 to 5.63)], confirming non-inferiority. Non-inferiority was confirmed considering an HIV-RNA >50 copies/mL (0% for 2DR; 3.7% for CAR; 95% CI = -0.4 to 7.9). Four patients reported adverse events not leading to treatment discontinuation (one patient in the 2DR group and three patients in the CAR group); eight subjects discontinued therapy in the 2DR group and three in the CAR group. With 2DR, lipid serum concentrations increased, but differences were statistically significant only for tenofovir disoproxil fumarate-containing CAR and in 2DR patients receiving a pre-switch regimen including tenofovir disoproxil fumarate. Median bone stiffness decreased in the CAR group from 86.1 g/cm2 (IQR = 74-98) to 83.2 g/cm2 (IQR = 74-97) and increased in the 2DR group from 84.9 g/cm2 (IQR = 74-103) to 85.5 g/cm2 (IQR = 74-101). The reduction within the CAR group was significant (P = 0.043).

CONCLUSIONS

Once-daily rilpivirine plus cobicistat-boosted darunavir is an effective 2DR that combines a high virological efficacy with a potential to avoid major NRTI toxicities.

AIDS Clinical Research in Spain-Large HIV Population, Geniality of Doctors, and Missing Opportunities

The first cases of AIDS in Spain were reported in 1982. Since then over 85,000 persons with AIDS have been cumulated, with 60,000 deaths. Current estimates for people living with HIV are of 145,000, of whom 20% are unaware of it. This explains the still high rate of late HIV presenters. Although the HIV epidemic in Spain was originally driven mostly by injection drug users, since the year 2000 men having sex with men (MSM) account for most new incident HIV cases. Currently, MSM represent over 80% of new yearly HIV diagnoses. In the 80s, a subset of young doctors and nurses working at Internal Medicine hospital wards became deeply engaged in attending HIV-infected persons. Before the introduction of antiretrovirals in the earlier 1990s, diagnosis and treatment of opportunistic infections was their major task. A new wave of infectious diseases specialists was born. Following the wide introduction of triple combination therapy in the late 1990s, drug side effects and antiretroviral resistance led to built a core of highly devoted HIV specialists across the country. Since then, HIV medicine has improved and currently is largely conducted by multidisciplinary teams of health care providers working at hospital-based outclinics, where HIV-positive persons are generally seen every six months. Antiretroviral therapy is currently prescribed to roughly 75,000 persons, almost all attended at clinics belonging to the government health public system. Overall, the impact of HIV/AIDS publications by Spanish teams is the third most important in Europe. HIV research in Spain has classically been funded mostly by national and European public agencies along with pharma companies. Chronologically, some of the major contributions of Spanish HIV research are being in the field of tuberculosis, toxoplasmosis, leishmaniasis, HIV variants including HIV-2, drug resistance, pharmacology, antiretroviral drug-related toxicities, coinfection with viral hepatitis, design and participation in clinical trials with antiretrovirals, immunopathogenesis, ageing, and vaccine development.

Dual Raltegravir-Etravirine Combination as Maintenance Regimen in Virologically Suppressed HIV-1-Infected Patients

Nucleoside reverse transcriptase inhibitor (NRTI)- and protease inhibitor (PI)-sparing antiretroviral regimens may be useful in selected human immune deficiency virus (HIV)-infected patients with resistance or intolerance to these drug classes. This was an observational prospective study of patients on suppressive antiretroviral therapy containing two NRTIs plus one ritonavir-boosted PI who switched to a dual regimen containing raltegravir plus etravirine. Patients were required not to have prior virological failure to raltegravir and to have efficacy of etravirine shown through the genotypic resistance assay in case of prior non-nucleoside reverse transcriptase inhibitor (NNRTI) virological failure. As a whole, 38 patients were enrolled. The mean duration of current regimen was 4.3 years, and the reason for simplification was toxicity in 29 patients and resistance to NRTIs in 9 patients. After switching, the percentage of patients with HIV RNA <20 copies/ml at week 48 was 81.6% in the intent-to-treat-exposed analysis. The switch led to a significant reduction in the mean serum triglyceride levels (-81.2 mg/dl), in the mean total cholesterol levels (-44.3 mg/dl), and in the prevalence of tubular proteinuria (-30.2%), with a significant increase in the mean phosphoremia (+0.52 mg/dl) and in both mean lumbar and femoral neck bone mineral density (+6.5% and +4.7%, respectively). Two patients (5.2%) had virological failure due to suboptimal adherence, and five subjects (13.1%) discontinued treatment due to adverse events. In our study, simplification to the dual-therapy raltegravir plus etravirine was associated with a good efficacy and tolerability, in addition to a favorable effect on kidney, bone, and serum lipids.

Lamivudine/dolutegravir dual therapy in HIV-infected, virologically suppressed patients

BACKGROUND

Little is known about the applicability of dual treatments based on integrase inhibitors. We explored the combination of lamivudine + dolutegravir as an option when switching from standard cART in virologically suppressed patients.

METHODS

In this prospective cohort we enrolled patients previously switched to 3TC + DTG who were 18 years or older, with no previous resistance mutations to the used drugs, having a HIV-RNA <50 copies/ml for 6 months or longer, negative for HBsAg and on a stable (>6 months) cART.

RESULTS

Ninety-four individuals were included. They were mostly men (77.7%) with a mean age of 53 years. They presented 159 co-morbidities including cardiovascular, bone, hepatic, kidney, and CNS diseases. Because of these pathologies, they took 207 non-ARV drugs (mean 2.2 per patient). Median duration of viral suppression was 77.5 months (IQR 61). All subjects were prospectively followed up to week 24 and all remained on dual therapy during the whole period. Neither virological failure, nor viral blip was detected. The median CD4 count rose from 658 cells/mcl (IQR 403) to 724 cells/mcl (IQR 401) (P = 0.006) without a significant (P = 0.44) change in the CD4/CD8 ratio. A significant (P < 0.0001) increment of median creatinine from 0.87 mg/dl (IQR 0.34) to 0.95 mg/dl (IQR 0.29) was observed in the first 2 months but thereafter leveled on these values (1.00 mg/dl; IQR 0.35) (P = 0.111 compared to 2 months). The lipid profile slightly improved. The daily cost of cART was significantly (P < 0.0001) reduced of 6.89 euros (SD 6.10).

DISCUSSION

Switching to a dual cART regimen based on lamivudine + dolutegravir maintains virological efficacy up to week 24, and is associated to slight improvements of the immunologic and metabolic status. The strategy allows to freely using concomitant medications for associated pathologies. The dual therapy is less expensive in economic terms.

CONCLUSION

Although still limited evidence exists, a dolutegravir-based dual therapy in combination with lamivudine shows promising results to be confirmed in larger controlled trials.

NRTI Sparing Therapy in Virologically Controlled HIV-1 Infected Subjects: Results of a Controlled, Randomized Trial (Probe)

Dual treatments could help clinicians to avoid drawbacks and toxicities due to the nucleosidic backbone, while maintaining the efficacy and convenience of robust combination antiretroviral therapy (cART). We explored the combination of rilpivirine plus boosted darunavir (DRV) as an option when switching from standard cART in patients who are virologically suppressed. In this randomized, open-label, proof-of-concept, noninferiority trial, we recruited patients aged 18 years or older with chronic HIV-1 infection and on a stable, effective (>6 months) protease inhibitor-based cART including a nucleosidic backbone. The primary endpoint was noninferiority of the virological response between treatment groups, according to FDA snapshot approach. Sixty patients were randomly allocated to dual treatment with rilpivirine plus boosted DRV or to continue their ongoing triple treatment. Noninferiority was shown at the prespecified level of -12% both at 24 and 48 weeks. At week 24, 100% of patients in the dual arm presented a blood HIV-RNA level <50 copies per milliliter compared with 90.1% in the triple drug arm (difference 9.9%, 95% CI: -0.7 to 20.7), whereas, at 48 weeks, the same proportions were 96.7% and 93.4%, respectively (difference 3.3%, 95% CI: -7.15 to 13.5). The mean change in CD4 cell count from baseline was 6.0 cells per microliter (SD, 184) for dual treatment and 16.5 cells per microliter (SD, 142) for triple treatment. A relevant decrement in CD838HLADR cells was observed in both arms. The reduction was, however, significantly more pronounced in the dual-therapy arm. At week 48, the CD838HLADR cell count was 3.4% (SD, 2.2) in the dual-therapy arm and 5.2% (SD, 3.1) in the triple arm (P = 0.018). None of the patients developed severe adverse events nor had to stop treatment because of adverse events or presented grade 3-4 laboratory abnormalities. A greater reduction of bone stiffness (-2.25; SD, 7.1) was observed in patients randomized to continue triple therapy compared with patients switched to dual therapy (-0.32; SD, 8.8). Finally, baseline HIV-DNA content directly correlated with pre-cART viral load of patients (P = 0.021), but not with time on cART or time with HIV-RNA below 50 copies per milliliter. Independently of the study arm, patients with a n HIV-RNA level constantly above 3 copies per milliliter or showing viral blips had baseline HIV-DNA levels significantly higher (64,656 copies per 10 cells; SD, 93057) compared with patients who constantly presented a HIV-RNA level below the detection limit of 3 copies per milliliter (14,457 copies per 10 cells; SD, 14098) (P = 0.001). A rilpivirine-boosted plus ritonavir-boosted DRV therapy was not inferior over 48 weeks to a standard boosted protease inhibitor-based triple cART. The dual therapy did not negatively affect lipid profile and renal function and was more friendly on bone metabolism. This approach constitutes an alternative for patients experiencing nucleoside reverse transcriptase inhibitor-related toxicities.

Dual Therapy Treatment Strategies for the Management of Patients Infected with HIV: A Systematic Review of Current Evidence in ARV-Naive or ARV-Experienced, Virologically Suppressed Patients

Objective

We reviewed the current literature regarding antiretroviral (ARV)-sparing therapy strategies to determine whether these novel regimens can be considered appropriate alternatives to standard regimens for the initial treatment of ARV-naive patients or as switch therapy for those patients with virologically suppressed HIV infection.

Methods

A search for studies related to HIV dual therapy published from January 2000 through April 2014 was performed using Biosis, Derwent Drug File, Embase, International Pharmaceutical Abstracts, Medline, Pascal, SciSearch, and TOXNET databases; seven major trial registries, and the abstracts of major conferences. Using predetermined criteria for inclusion, an expert review committee critically reviewed and qualitatively evaluated all identified trials for efficacy and safety results and potential limitations.

Results

Sixteen studies of dual therapy regimens were critiqued for the ARV-naive population. Studies of a protease inhibitor/ritonavir in combination with the integrase inhibitor raltegravir or the nucleoside reverse transcriptase inhibitor lamivudine provided the most definitive evidence supporting a role for dual therapy. In particular, lopinavir/ritonavir or darunavir/ritonavir combined with raltegravir and lopinavir/ritonavir combined with lamivudine demonstrated noninferiority to standard of care triple therapy after 48 weeks of treatment. Thirteen trials were critiqued in ARV-experienced, virologically suppressed patients. The virologic efficacy outcomes were mixed. Although overall data regarding toxicity are limited, when compared with standard triple therapy, certain dual therapy regimens may offer advantages in renal function, bone mineral density, and limb fat changes; however, some dual combinations may elevate lipid or bilirubin levels.

Conclusions

The potential benefits of dual therapy regimens include reduced toxicity, improved tolerability and adherence, and reduced cost. Although the data reviewed here provide valuable insights into the effectiveness and tolerability of dual therapy regimens, it remains unclear whether these potential benefits can be maintained long-term. Appropriately powered studies with longer follow-up periods are needed to more definitively assess potential toxicity reduction advantages with dual therapy.

Efficacy and safety of darunavir/ritonavir plus etravirine dual regimen in antiretroviral therapy-experienced patients: a multicenter clinical experience

OBJECTIVES

To assess the outcome of a dual regimen combining darunavir/ritonavir plus etravirine in a cohort of antiretroviral therapy (ART)-experienced patients.

METHODS

A retrospective analysis was performed on all ART-experienced patients starting a darunavir/ritonavir plus etravirine regimen at the 3 clinics. Patients were stratified according to HIV RNA detectability (≥ 40 copies/mL) at baseline. Two efficacy endpoints were evaluated by Kaplan-Meier and Cox multivariable models: virological failure (confirmed HIV RNA ≥ 40 copies/mL after 6 months) and therapeutic failure (including virological failure and treatment discontinuation for any reason).

RESULTS

Sixty-eight patients were included in the study. They had a median of 10.8 years on ART and 5 previous ART regimens; 61.3% showed primary protease inhibitor (PI) mutations and 70% showed previous non-nucleoside reverse transcriptase inhibitor (NNRTI) exposure. HIV RNA was detectable in 34 (50%) patients. The median observation period was 21 (interquartile range [IQR], 11.9-25.1) months. After 24 months, 75.1% of the patients were still on the study regimen and 88.8% remained free from virological failure. Although a higher therapeutic failure rate was reported in patients with detectable viremia at baseline, only the immunological status revealed an independent predictive role. No differences in virological failure were observed according to HIV RNA detectability at baseline; a higher number of previous ART regimens was the only predictor. Discontinuation due to adverse events occurred in 5.9%.

CONCLUSIONS

Darunavir/ritonavir plus etravirine regimen proved virological efficacy and safety in heavily pretreated patients with a high rate of virological success, even in patients who switched during virological failure.

Nucleoside-sparing antiretroviral regimens

Nucleoside reverse transcriptase inhibitors (NRTIs) were the first drugs approved for use as antiretroviral therapy in patients infected with HIV. Despite the introduction of other classes of antiretroviral drugs, they remain an important component of combination regimens as recommended by many treatment guidelines. They also continue to be used in prevention of disease from mother to child, postexposure prophylaxis, and more recently for preexposure prophylaxis. Unfortunately, the toxicities associated with this class of drugs can limit their use. Although NRTI-sparing regimens are not currently recommended for first-line therapy there is an increasing amount of data supporting their use in both treatment-naive and in treatment-experienced patients.

Short communication: lamivudine plus a boosted-protease inhibitor as simplification strategy in HIV-infected patients: proof of concept

There are scarce data about the use of a dual therapy with lamivudine plus a ritonavir-boosted protease inhibitor (PI/r) as simplification strategy. We performed a retrospective cohort study of 44 HIV-infected patients on suppressive triple therapy PI/r-based HAART, HBV negative, who discontinued one nucleoside analogue (NA) due to toxicity, and continued dual therapy with lamivudine plus the PI/r. The median time of HIV infection was 18.6 years, and CD4(+) count nadir was 150 cells/μl (6-470). They had received a mean of four regimens before (2-20), and 55% had a previous AIDS diagnosis. In eight cases, a previous resistance test showed two to seven secondary mutations in the protease gene, without resistance to the PI/r. The 184V mutation was not observed, but previous failure with a lamivudine-including regimen had been observed in four patients (9%). At baseline, patients had viral suppression (<50 copies/ml) for a median time of 794 days (235-2344), while receiving atazanavir/r in five cases, lopinavir/r in 14, and darunavir/r in 25. They discontinued mainly tenofovir (19, 43%) and didanosine (15, 34%). During 101.5 patient-years of follow-up, only two patients failed (5%), because of incomplete adherence. CD4(+) count increase at 48 weeks was 55 cells/μl. No new adverse events were observed, although total cholesterol and triglycerides increased significantly during the first 6 months after simplification. In conclusion, dual therapy with lamivudine plus a boosted PI was safe and effective as simplification strategy in patients with toxicity to NA. This combination could be an alternative to mono or triple therapy in hard-to-treat patients.

Pharmacological and clinical evidence of nevirapine immediate- and extended-release formulations

We reviewed the current information available on nevirapine immediate- and extended-release formulations and its role in single-dose and combination antiretroviral therapy. Nevirapine was approved in 1996 and was the first non-nucleoside reverse-transcriptase inhibitor available for the treatment of HIV-1 infection. Nevirapine has demonstrated good efficacy and a well-characterized safety profile. A major drawback is the low genetic barrier, allowing the emergence of resistance in the presence of single mutations in the reverse-transcriptase gene. This shortcoming is particularly relevant when nevirapine is administered in a single dose to prevent mother-to-child transmission of HIV-1 infection, compromising the efficacy of future non-nucleoside reverse transcriptase-inhibitor regimens. Studies published recently have probed the noninferiority of nevirapine compared to ritonavir-boosted atazanavir with both tenofovir disoproxil fumarate and emtricitabine in antiretroviral treatment-naïve patients. In 2011, a new formulation of nevirapine (nevirapine extended release) that allowed once-daily dosing was approved by the Food and Drug Administration and by the European Medicines Agency. VERxVe, a study comparing nevirapine extended release with nevirapine immediate release in antiretroviral treatment-naïve patients, and TRANxITION, a study carried out in antiretroviral treatment-experienced patients who switched therapy from nevirapine immediate release to nevirapine extended release, provided data on the noninferiority of the new formulation of nevirapine compared with nevirapine immediate release in terms of efficacy and safety. Nevirapine extended release will further increase the durability and persistence of nevirapine-containing antiretroviral therapy, allowing once-daily dosing regimens.

Noninfectious HIV-related comorbidities and HAART toxicities: choosing alternative antiretroviral strategies

In the HAART era, clinicians are faced with the challenge of treating an aging HIV-infected population increasingly affected by severe comorbidities, which may compromise the tolerability of antiretroviral regimens. In this special population, it is imperative for physicians to carefully tailor antiretroviral treatment in order not to worsen patients’ underlying clinical conditions and to achieve both tolerability and immune–virologic efficacy. This article aims to explore the impact of standard HAART regimens on the different noninfectious HIV-related comorbidities: metabolic, cardiovascular, bone and renal diseases, in order to provide tools to fit the most appropriate antiretroviral combination according to individual clinical conditions. Clinical experience with alternative antiretroviral strategies, avoiding nucleoside reverse transcriptase inhibitor toxicities and involving new antiretroviral classes, will be reviewed to obtain an overview on future perspectives.

Boosted protease inhibitors as a therapeutic option in the treatment of HIV-infected children

OBJECTIVE

Paediatric HIV treatment must address various special considerations. Administration of pharmacokinetically enhanced protease inhibitors (PIs) can improve paediatric therapeutic outcomes. The objective of this study was to review the use of boosted PI regimens in children.

METHODS

Systematic literature searches of published manuscripts and conference databases using generic drug names and specific keywords were performed to ensure thorough and balanced reporting of available data.

RESULTS

Boosted PI regimens offer multiple options across a range of ages and are efficacious in naïve and experienced children; safety and tolerability are similar to those observed in adults. Novel boosted PI simplification approaches may foster adherence and diminish resistance.

CONCLUSIONS

Boosted PIs are key components of first- and second-line treatments in children. Identifying factors associated with the response to highly active antiretroviral therapy in children may ultimately permit individualized therapies.

Improvement in lipid profiles over 6 years of follow-up in adults with AIDS and immune reconstitution

OBJECTIVES

The aim of the study was to evaluate long-term changes in lipids and to assess other coronary heart disease (CHD) risk factors in highly experienced AIDS patients with immune reconstitution, and to examine their association with antiretroviral therapy (ART).

METHODS

We evaluated 433 AIDS patients with prior severe immunosuppression and ART-based immune reconstitution, followed in a multicentre prospective observational study between 2000 and 2006. We estimated the prevalence at entry of hypercholesterolaemia and metabolic syndrome, and 10-year CHD risks. Trends in total cholesterol (TC), triglycerides (TG) and high-density lipoprotein (HDL) cholesterol were evaluated over time, and use of specific ART drugs at each study visit was assessed using mixed effect models, adjusting for CHD risk factors and use of lipid-lowering agents.

RESULTS

At entry to observational follow-up, 28% of the 433 subjects had hypercholesterolaemia and 15% had a predicted 10-year CHD risk above 20%. Average TC and fasting TG levels declined over the follow-up period (median=5.8 years), and these declines were associated with increased use of physician-prescribed lipid-lowering agents and changes in ART regimens. After adjustment for CHD risk factors, TC and TG levels were significantly higher for those on ritonavir-boosted protease inhibitors and those on nonnucleoside reverse transcriptase inhibitors (NNRTIs), particularly efavirenz, than for other patients.

CONCLUSIONS

Abnormalities in serum lipids were common at baseline but became less so over time, and this improvement was associated with increased use of lipid-lowering agents and selection of ART agents with less deleterious effects on lipids.

Lipodystrophy syndromes

Lipodystrophy syndromes comprise a group of rare, heterogeneous disorders characterized by progressive loss of fat tissue, mainly from subcutaneous compartment and occasionally affecting visceral fat. Lipoatrophy may be partial, localized, or generalized. The latter cases are usually accompanied by metabolic-related disorders, including insulin resistance, diabetes mellitus, hyperlipemia, progressive hepatic disease and anabolic state. Treatment for lipodystrophy has increased interest in recent years because a new lipoatrophic population-patients who have HIV-associated lipodystrophy--is much more numerous than the whole number of patients affected by classic lipodystrophy entities.

Constant mitochondrial DNA levels in blood leukocytes of patients enrolled in a NRTI-free therapeutic trial (BIKS-2 study)

OBJECTIVES

Determine if a nucleoside reverse transcriptase inhibitors (NRTI)-free regimen affected mitochondrial DNA (mtDNA) levels in peripheral blood mononuclear cells (PBMCs) of patients enrolled in BIKS-2 trial.

METHODS

Antiretroviral (ARV) naïve (N=13) and NRTI experienced (N=7) patients, received lopinavir/ritonavir, a boosted protease inhibitor, and efavirenz, a non-nucleoside reverse transcriptase inhibitor from Month (M) 0 to M12 (1-year BIKS trial) and from M12 to M36 (2-year BIKS-2 trial). MtDNA was quantified at M12, M24 and M36 via real-time PCR assay.

RESULTS

From M12 to M36, the 20 patients have maintained undetectable plasma HIV-1 RNA, gained CD4 cells and had no side effects attributable to these drugs. Median mtDNA contents were constant: 478.6 at M12, 478.6 at M24 and 324.4 copies/cell at M36 (pM12-M36=0.5). Because M0 data is missing, these results were compared to those of two groups of age matched individuals: healthy donors and HIV-infected patients before and after exposure to NRTIs. Healthy donors have higher contents (871), followed by patients never treated (602), than by BIKS patients where 7 had toxic NRTIs (478.6) and at last by patients exposed for six months to the most toxic combination (ddI-d4T) (85 copies/cell).

CONCLUSION

Lopinavir/ritonavir+efavirenz did not affect mtDNA contents in PBMCs.

Pharmacokinetic drug interactions with non-nucleoside reverse transcriptase inhibitors

Non-nucleoside reverse transcriptase inhibitors (NNRTIs) are a diverse group of compounds that inhibit HIV Type 1 reverse transcriptase. Although possessing a common mechanism of action, the approved NNRTIs, delavirdine, efavirenz and nevirapine, differ in structural and pharmacokinetic characteristics. Each of the NNRTIs undergoes biotransformation by the cytochrome P450 (CYP) enzyme system, thus making them prone to clinically significant drug interactions when combined with other antiretrovirals. In addition, they interact with other concurrent medications and complementary/alternative medicines, acting as either inducers or inhibitors of drug-metabolising CYP enzymes. These drug interactions become an important consideration in the clinical use of these agents when designing combination regimens, as recommended by current guidelines. This review provides an updated summary of pharmacokinetic interactions with NNRTIs.

[Mitochondrial cytopathies associated with HIV infection]

The tremendous progress achieved during the last few years with the use of highly active antiretroviral therapy in suppressing HIV replication together with improvements in immunity have been tempered by a growing number of new adverse effects. Mitochondrial toxicity is one aspect of these long-term toxicities of antiretroviral drugs, with the role of nucleoside analogs particularly underlined. Some cases of impaired mitochondrial function have been clearly identified, such as pancreatitis due to didanosine, neuropathy due to zalcitabine, myopathy due to zidovudine, and lactic acidosis due to stavudine. These mitochondrial toxicities can affect several organs, presenting different patterns of symptoms: from asymptomatic to states with few symptoms despite huge metabolic abnormalities whose prognosis is immediately life-threatening. Beyond the inhibition of DNA polymerase gamma using nucleoside analogs, responsible for decreasing mitochondrial DNA in certain targeted organs, it appears that several physiopathologic mechanisms interact to explain this observed toxicity, HIV itself plays a role, and the underlying genetic pool needs to be better identified. Such cases mean that, it is imperative to avoid cumulated toxicities caused by associated treatments. With serious cases, or persistent symptoms despite discontinuing the nucleoside analogs responsible for such toxicity, one must propose vitamins, mitochondrial co-factors, or anti-oxidants. However, the future lies in the use of potent, less toxic nucleoside analogs, and in developing compounds belonging to other classes of antiretrovirals.

Safety of lopinavir/ritonavir for the treatment of HIV-infection

Kaletra, a fixed-dose co-formulation of lopinavir/ritonavir, was the first boosted protease inhibitor developed for the treatment of HIV-infection. In September 2000, the US FDA granted Kaletra fast-track approval as data showed a higher efficacy in the treatment of HIV-infection than standard protease inhibitors of that time. Although potency was of major concern in the early years of highly active antiretroviral therapy (HAART), presently, with the perspective of HIV-infection becoming a chronic but well controllable disease, other issues begin to draw increased attention in the long-term management of HIV-infected patients. Among general health issues such as cardiovascular disease, metabolic disorders or hepatitis co-infection, the long-term toxicity and safety of HAART is an important concern when choosing antiretroviral drugs for each individual patient. In this review, the authors report on the safety of lopinavir/ritonavir in the treatment of HIV-infected patients, and focus on special patient groups and relevant safety issues.

Mitochondrial Studies in Haart-Related Lipodystrophy: From Experimental Hypothesis to Clinical Findings

Chronic use of antiretrovirals (ARVs) to treat HIV infection, along with more prolonged patient survival, has been associated with an increase in adverse drug effects in HIV-infected patients on treatment. It has been proposed that some of these adverse effects (including myopathy, cardiomyopathy, anaemia, hyperlactataemia/ lactic acidosis, pancreatitis, polyneuritis and lipodystrophy) could be mediated by mitochondrial (mt) toxicity. From the experimental data, it has been proposed that nucleoside analogue reverse transcriptase inhibitors (NRTIs) also inhibit γ-polymerase, the enzyme devoted to replicate (and, to a lesser extent, repair) mtDNA. It is now widely accepted that the use of most NRTIs in HIV-infected patients is associated with mtDNA depletion. Although cross-sectional studies suggest that certain ARVs, especially stavudine, are more toxic to mitochondria, the differences among different highly active ARV therapy (HAART) schedules detected in the analysis of longitudinal studies are not so clear. These types of study in previously untreated individuals suggest that the greatest mtDNA loss appears at the beginning of the treatment. Conversely, in ARV-experienced patients, the potential beneficial effects of HAART changes in terms of mtDNA content remain controversial and must be further investigated. Functional studies accompanying genetic investigations are needed for the correct pathogenic interpretation of the mtDNA abnormalities.