Hydroxyurea-induced hepatitis in human immunodeficiency virus-positive patients

A cure for AIDS: a matter of timing?

Despite the huge clinical success of antiretroviral therapy, several factors such as side effects, requirement of life-long adherence, high cost, incomplete access to therapies and development of drug resistance make the quest for an ultimate cure of HIV/AIDS a worldwide priority of biomedical research. In this respect, several sterilizing or functional cures have been reported in the last years in both non-human primates and humans. This review provides a summary of the main results achieved so far, outlining their strengths as well as their limitations. A synthetic interpretation of these results could be pivotal in order to develop an effective and widely available cure.

Hydroxyurea in the treatment of HIV infection: clinical efficacy and safety concerns

Data from basic science and clinical studies suggest that hydroxyurea (hydroxycarbamide)-based regimens are effective treatment options for patients with HIV at various stages of disease. In vitro studies of HIV-infected lymphocytes have shown that hydroxyurea: (i) inhibits viral DNA synthesis; (ii) synergistically interacts with nucleoside reverse transcriptase inhibitors (NRTI); and (iii) increases the antiviral activity of didanosine. Clinical studies have confirmed that hydroxyurea in combination with didanosine produces potent and sustained viral suppression in patients with HIV infection. However, some concerns have been recently raised on the use of hydroxyurea in association with NRTI. Hydroxyurea can cause myelosuppression, skin toxicities, mild gastrointestinal toxicity, and abnormalities of renal and liver functions. In addition, hydroxyurea may accentuate the toxic effects of nucleoside analogues. In fact, some clinical data seem to indicate an increased risk of pancreatitis and neuropathy when hydroxyurea is combined with didanosine and stavudine. Since hydroxyurea-related toxicity is dose dependent, a systematic study of hydroxyurea optimal dosage and schedule was initiated to monitor patients for possible nucleoside toxicity. In the Research Institute for Genetic and Human Therapy (RIGHT) 702 study it was shown that a low, well-tolerated hydroxyurea dose (600 mg daily) achieved better antiretroviral activity than higher doses, together with better CD4+ cell count increase and fewer adverse effects. In this paper the effects of hydroxyurea as salvage therapy for heavily pretreated patients with advanced HIV disease are presented. These studies have shown that some patients with extensive pretreatment experience and advanced disease can respond substantially to the addition of hydroxyurea. The addition of hydroxyurea to didanosine does not prevent the emergence of resistance to didanosine; nonetheless, the efficacy of this therapeutic regimen may not be attenuated by the presence of didanosine-resistant HIV mutants. Since CD4 T lymphocyte activation is essential for virus replication and CD8 T lymphocyte activation may contribute to pathogenesis, the combination of hydroxyurea with other drugs may lead to the inhibition of HIV, by blocking the 'cell activation-virus production-pathogenesis' cycle. Clinical data indicate that hydroxyurea may play a role in attenuation of viral rebound and immune reconstitution by decreasing CD4 T cell proliferation, as well as preventing the exhaustion of CD8 T cell populations that may result from excessive activation during HIV infection. While the combination of hydroxyurea with didanosine has provided hope, future studies including those that evaluate optimal dosing and long-term toxicity are needed to define the role for this agent in the treatment of HIV infection.

[Recommendations of the Spanish AIDS Study Group (GESIDA) and the National Aids Plan (PNS) for antiretroviral treatment in adult patients with human immunodeficiency virus infection in 2002]

OBJECTIVE

To provide an update of recommendation on antiretroviral treatment (ART) in HIV-infected adults.Methods. These recommendations have been agreed by consensus by a committee of the spanish AIDS Study Group (GESIDA) and the National AIDS Plan. To do so, advances in the physiopathology of AIDS and the results on efficacy and safety in clinical trials, cohort and pharmacokinetics studies published in biomedical journals or presented at congresses in the last few years have been reviewed. Three levels of evidence have been defined according to the data source: randomized studies (level A), case-control or cohort studies (level B) and expert opinion (level C). Whether to recommend, consider, or not to recommend ART has been established for each situation.

RESULTS

Currently, ART with combinations of at least three drugs constitutes the treatment of choice in chronic HIV infection. In patients with symptomatic HIV infection, initiation of ART is recommended. In asymptomatic patients initiation of ART should be based on the CD41/mL lymphocyte count and on the plasma viral load (PVL): a) in patients with CD41 lymphocytes < 200 cells/mL, initiation of ART is recommended; b) in patients with CD41 lymphocytes between 200 and 300 cells/mL, initiation of ART should, in most cases, be recommended; however, it could be delayed when the CD41 lymphocyte count remains close to 350 cells/mL and the PVL is low, and c) in patients with CD41 lymphocytes > 350 cells/mL, initiation of ART can be delayed. The aim of ART is to achieve an undetectable PVL. Adherence to ART plays a role in the durability of the antiviral response. Because of the development of cross-resistance, the therapeutic options in treatment failure are limited. In these cases, genotypic analysis is useful. Toxicity limits ART. The criteria for ART in acute infection, pregnancy and postexposure prophylaxis and in the management of coinfection with HIV and hepatitis C and B virus are controversial.

CONCLUSIONS

The current approach to initiating ART is more conservative than in previous recommendations. In asymptomatic patients, the CD41 lymphocyte count is the most important reference factor for initiating ART. Because of the considerable number of drugs available, more sensitive monitoring methods (PVL) and the possibility of determining resistance, therapeutic strategies have become much more individualized.

Effects of treatment intensification with hydroxyurea in HIV-infected patients with virologic suppression

BACKGROUND

Virologic rebound can result from suboptimal antiviral potency in combination antiretroviral therapy.

DESIGN

Multicenter, partially blinded, prospective, randomized study of 202 HIV-infected subjects to determine whether therapy intensification improves long-term rates of virologic suppression.

METHODS

Subjects had plasma HIV RNA < 200 copies/ml, CD4 cell count of > 200 x 10(6) cells/l, and treatment with indinavir (IDV) + zidovudine (ZDV) + lamivudine (3TC) for at least 6 months before randomization to stay on this regimen or to receive IDV + didanosine (ddI) + stavudine (d4T) plus or minus hydroxyurea (HU) (600 mg twice daily). Treatment failure was defined as either confirmed rebound of HIV RNA level to > 200 copies/ml or a drug toxicity necessitating treatment discontinuation.

RESULTS

Treatment failure occurred more frequently in subjects randomized to the HU-containing arm (32.4%), than in those taking IDV + ddI + d4T (17.6%) or IDV + ZDV + 3TC (7.6%). The time to treatment failure was shorter for the HU-containing arm compared with the IDV + ZDV + 3TC (P < 0.0001) or IDV + ddI + d4T arms (P = 0.032). Dose-limiting toxicities rather than virologic rebound accounted for the differences between treatment failure among the study arms. Pancreatitis led to treatment discontinuation in 4% of subjects in treatment arms containing ddI + d4T. Three subjects with pancreatitis died, all randomized to the HU-containing arm.

CONCLUSIONS

Switching to IDV + ddI + d4T + HU in patients treated with IDV + ZDV + 3TC was associated with a worse outcome, principally because of drug toxicity.

Combination therapy with hydroxyurea versus without hydroxyurea as first line treatment options for antiretroviral-naive patients

PURPOSE

This study analyzed whether combination therapy with hydroxyurea (HU) could be considered as first line treatment for antiretroviral-naive patients.

METHOD

The prospective open-label study was carried out from March 1996 to May 2000. The antiretroviral treatments were treatment 1-didanosine 400 mg/day, stavudine 60/80 mg/day, and HU 500 mg/day; treatment 2-two nucleosides plus a protease inhibitor; treatment 3-didanosine, indinavir, and HU (500-1,000 mg/day). The viral load (VL) and CD4 determinations were performed at weeks 24, 48, 72, and 96.

RESULTS

The sample comprised 284 patients. The distribution of patients by levels of VL and CD4 were similar in the three treatment groups. At week 24, patients receiving T1 and T3 achieved higher percentages of undetectable VL (89% and 81%, respectively) with no significant differences (p =.127) between them. The T2 group showed a lower proportion (58%) of undetectable VL, which was significantly lower than T1 (p <.0001) and T3 (p <.0007). At week 48, the results were similar to week 24. At week 96, nearly all patients had undetectable viral load (UVL). The analysis of adverse effects showed that the T2 group at week 48 had a greater proportion of adverse effects that was significantly different from T1 (p =.0026); T3 had intermediate values with no significant difference from T2 (p =.45) and from T1 (p =.048). At week 48, T1 showed higher adherence level with significant difference from the other two treatments.

CONCLUSION

Patients were followed for some 96 weeks and, with an intention-to-treat analysis, were found to do better virologically and Clinically in treatment groups containing HU. The combination of antiretroviral drugs with HU may be an excellent option as initial therapy because of its strong antiretroviral action, its lower rate of adverse effect, and the smaller cost as compared to other regimens.

Clinical manifestations and management of antiretroviral nucleoside analog-related mitochondrial toxicity

OBJECTIVES

This article reviews the clinical manifestations of mitochondrial toxicity associated with the use of nucleoside analog reverse transcriptase inhibitors (NRTIs) and outlines strategies to manage these sequelae.

BACKGROUND

NRTIs are the key components of the antiretroviral combinations used in the management of patients infected with HIV. The available NRTIs differ in their convenience of administration, frequency of dosing, resistance profiles, and side-effect profiles. NRTIs act as competitive inhibitors of the RNA/DNA polymerase reverse transcriptase of HIV and cause chain termination in the growing viral DNA chain. Many of the important and treatment-limiting side effects of NRTIs may be related to the effect of these agents on human DNA polymerases, in particular, mitochondrial DNA polymerase gamma. Depletion of mitochondrial DNA during chronic NRTI therapy may lead to cellular respiratory dysfunction and generalized and tissue- and drug-specific toxicities, including myopathy, peripheral neuropathy, and lactic acidosis. Recently, it has been proposed that the fat redistribution syndrome, or lipodystrophy, reported during chronic antiretroviral therapy is a manifestation of the differential impact of at least some NRTIs on peripheral and visceral adipocytes. Management of potential mitochondrial toxicity during NRTI therapy remains a challenge. A range of nutritional supplements, both as treatments and prophylaxes, have been proposed, and some have been investigated in vitro; no in vivo studies have yet been conducted.

METHODS

The information in this review was compiled using MEDLINE and AIDSLINE searches of the literature, including conference abstracts.

CONCLUSIONS

At present, interruption of NRTI therapy or substitution of the probable causative agent with alternative NRTIs that appear to be better tolerated represents the mainstay of management for mitochondrial toxicity and its clinical manifestations.

Mitochondrial toxicity of nucleoside analogue reverse transcriptase inhibitors: a looming obstacle for long-term antiretroviral therapy?

Nucleoside reverse transcriptase inhibitors suppress HIV replication by blocking reverse transcriptase, an RNA-dependent DNA polymerase. These drugs can also affect cellular and mitochondrial DNA polymerases. Mitochondrial DNA polymerase gamma is particularly sensitive to nucleoside reverse transcriptase inhibitors, and the majority of adverse effects caused by nucleoside reverse transcriptase inhibitors are most likely caused by mitochondrial dysfunction. This article reviews the recent clinical implications of nucleoside reverse transcriptase inhibitor-induced mitochondrial toxicity and discusses options for management.

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