A randomized, double-blind trial of half versus standard dose of zidovudine plus zalcitabine in Thai HIV-1-infected patients (study HIV-NAT 001). HIV Netherlands Australia Thailand Research Collaboration

Where latest advances in HIV are shared: 21st Bangkok International Symposium on HIV Medicine

Bangkok International Symposium on HIV Medicine is the largest regional conference on clinical HIV medicine in Southeast Asia. Held annually during the third week of January and spanning 3 days, the symposium provides updates on HIV and co-infection treatment and prevention. It is sponsored by HIV Netherlands Australia Thailand Research Collaboration (HIV-NAT), the first and largest clinical research center in Thailand and region. HIV-NAT was founded by the late David Cooper, late Joep Lange and Emeritus Praphan Phanuphak, who dedicated their lives to making HIV care and treatment accessible to people living with HIV in Thailand and throughout the developing world. The symposium continues its tradition of bringing the latest information in the field of HIV medicine to healthcare professionals.

A 72-week randomized study of the safety and efficacy of a stavudine to zidovudine switch at 24 weeks compared to zidovudine or tenofovir disoproxil fumarate when given with lamivudine and nevirapine

BACKGROUND

Due to superior long-term toxicity profiles, zidovudine (AZT) and tenofovir disoproxil fumarate (TDF) are preferred over stavudine (d4T) for first-line antiretroviral regimens. However, short-term d4T use could be beneficial in avoiding AZT-induced anaemia.

METHODS

We randomized (1:1:1) 150 treatment-naive Thai HIV-infected adults with CD4(+) T-cell count <350 cells/mm(3) to arm 1 (24-week GPO-VIR S30(®) [d4T plus lamivudine (3TC) plus nevirapine (NVP)] followed by 48-week GPO-VIR Z250(®) [AZT plus 3TC plus NVP]), arm 2 (72-week GPO-VIR Z250(®)) or arm 3 (72-week TDF plus emtricitabine [FTC] plus NVP). Haemoglobin (Hb), dual energy x-ray absorptiometry, neuropathic signs, estimated glomerular filtration rate (eGFR), CD4(+) T-cell count, plasma HIV RNA and adherence were assessed.

RESULTS

In an intention-to-treat analysis, mean Hb decreased from baseline to week 24 in arm 2 compared with arm 1 (-0.19 versus 0.68 g/dl; P=0.001) and arm 3 (0.48 g/dl; P=0.010). Neuropathic signs were more common in arm 2 compared with arm 3 (20.4 versus 4.2%; P=0.028) at week 24. There were no differences in changes in peripheral fat and eGFR from baseline to weeks 24 and 72 among arms. CD4(+) T-cell count increased more in arm 1 than arms 2 and 3 from baseline to week 24 (168 versus 117 and 118 cells/mm(3); P=0.01 and 0.02, respectively) but the increase from baseline to week 72 was similar among arms.

CONCLUSIONS

A 24-week d4T lead-in therapy caused less anaemia and greater initial CD4(+) T-cell count increase than initiating treatment with AZT. This strategy could be considered in patients with baseline anaemia or low CD4(+) T-cell count. If confirmed in a larger study, this may guide global recommendations on antiretroviral initiation where AZT is more commonly used than TDF.

Drug-induced hypoglycaemia: an update

Drugs are the most frequent cause of hypoglycaemia in adults. Although hypoglycaemia is a well known adverse effect of antidiabetic agents, it may occasionally develop in the course of treatment with drugs used in everyday clinical practice, including NSAIDs, analgesics, antibacterials, antimalarials, antiarrhythmics, antidepressants and other miscellaneous agents. They induce hypoglycaemia by stimulating insulin release, reducing insulin clearance or interfering with glucose metabolism. Several drugs may also potentiate the hypoglycaemic effect of antidiabetic agents. Administration of these agents to individuals with diabetes mellitus is of most concern. Many of these drugs, and depending on clinical setting, may also induce hyperglycaemia. Drug-induced hepatotoxicity and nephrotoxicity may lead in certain circumstances to hypoglycaemia. Some drugs may also induce hypoglycaemia by causing pancreatitis. Drug-induced hypoglycaemia is usually mild but may be severe. Effective clinical management can be handled through awareness of this drug-induced adverse effect on blood glucose levels. Herein, we review pertinent clinical information on the incidence of drug-induced hypoglycaemia and discuss the underlying pathophysiological mechanisms, and prevention and management.

HIV drug resistance transmission threshold survey in Bangkok, Thailand

Background

Antiretroviral therapy (ART) began in Thailand in the Bangkok Metropolitan Area (BMA) in 1988 and scale-up began in 2001. The national first-line regimen is stavudine, lamivudine and nevirapine in fixed-dose combination, which is a regimen with a low genetic barrier for resistance. Because viral load and resistance testing are not widely available, unidentified HIV drug resistance (HIVDR) may occur during treatment and could be transmitted.

Methods

We undertook a threshold survey to assess HIVDR transmission in two subsets of recently infected individuals in the BMA. The first group consisted of returning blood donors tested at the Thai Red Cross National Blood Centre who seroconverted within the past 12 months. The second group comprised recently infected (as defined by BED assay) clients of the Thai Red Cross voluntary counselling and testing centre (VCT).

Results

Genotyping of 50 consecutive specimens each from blood donors and VCT clients during 2005–2006 showed no mutations associated with HIVDR in the reverse transcriptase or protease regions of the HIV pol gene. These results are categorized by the WHO HIV drug resistance threshold survey method as representing a low prevalence (<5%) of transmitted HIV drug resistance.

Conclusions

Every effort should be made to minimize the emergence of resistance in treated individuals and to prevent primary and secondary HIV transmission. To continue to monitor HIVDR transmission, Thailand has planned additional surveys – including longitudinal surveys – in these and additional groups of individuals.

The Impact of Reducing Stavudine dose versus switching to tenofovir on plasma lipids, body composition and mitochondrial function in HIV-infected patients

Background

Stavudine (d4T)-containing regimens are associated with a potential for lipoatrophy and dyslipidaemia. We assessed the safety and efficacy of reducing the dose of stavudine compared with switching to tenofovir or maintaining the standard dose of d4T.

Methods

Clinically stable HIV-infected patients receiving antiretroviral therapy containing stavudine 40 mg twice daily with a plasma HIV RNA <200 copies/ml for at least 6 months were randomized to maintain stavudine 40 mg twice daily (d4T40 arm), to reduce to 30 mg twice daily (d4T30 arm), or to switch from d4T to tenofovir (TDF arm).

Results

Fifty-eight (93% male) patients were included: 22 in the d4T40 arm, 19 in the d4T30 arm and 17 in TDF arm. At baseline, median time on d4T was 6 years (interquartile range [IQR] 2.6–7.1), median age 43 years (IQR 36–51) and median CD4+ T-cell count was 587/mm3 (IQR 329–892). At week 24, median limb fat changes (g) were as follows: d4T40=-182 (95% CI: -469—5); d4T30=527 (95% CI: -343–694); and TDF=402 (95% CI: 130–835; d4T40 versus TDF, P=0.0003). Significant differences between median values of laboratory parameters were detected: triglycerides (mg/dl): d4T40=19; d4T30=-23 and TDF=-79 (d4T40 versus TDF, P=0.03); and total cholesterol (mg/dl): d4t40=22, d4T30=-4, and TDF=-28 (d4T40 versus TDF, P=0.04). No significant difference was observed in mitochondrial function assessed in peripheral blood mononuclear cells.

Conclusions

Although both strategies were associated with a trend toward a decrease in plasma lipids and an increase in body fat, the only significant changes were observed among those who switched to tenofovir.

The 48-week efficacy of once-daily saquinavir/ritonavir in patients with undetectable viral load after 3 years of antiretroviral therapy

OBJECTIVES

To evaluate the efficacy and safety of once-daily saquinavir-soft-gel-capsules/ritonavir (SQV-SGC/RTV) 1600 mg/100 mg plus dual nucleoside reverse transcriptase inhibitors (NRTIs) in HIV-infected patients with plasma viral load (pVL) <50 HIV-1 RNA copies/mL following 3 years of antiretroviral therapy.

METHODS

A total of 69 patients with pVL <50 copies/mL after 162 weeks of antiretroviral treatment started SQV-SGC/RTV 1600 mg/100 mg once-daily while continuing dual NRTIs. Previous treatment consisted of 66 weeks of treatment with a half/full dose of zidovudine (ZDV)/zalcitabine (ddC), followed by 2 years of SQV-SGC twice a day (bid) plus ZDV/lamivudine (3TC) or didanosine (ddI)/stavudine (d4T). Efficacy (pVL), safety and immunological changes (CD4 cell counts) were evaluated after 48 weeks in this open-label, single-arm prospective study.

RESULTS

SQV-SGC/RTV once-daily was well tolerated. No patient changed regimens or was lost to follow-up. After 48 weeks, 63 of 69 patients (91%) had pVL <50 copies/mL (five of the six remaining patients had pVL <400 copies/mL, and one patient had an unexplained rise to 39 500 copies/mL, which decreased to <50 copies/mL 12 weeks later). Median CD4 count increased from 534 cells/muL at the start of the SQV-SGC/RTV once-daily treatment to 664 cells/muL (P<0.001). Compared to the preceding 48 weeks on bid SQV-SGC, the CD4 cell count improved significantly on once-daily SQV-SGC/RTV (P<0.001).

CONCLUSIONS

These data support the use of SQV-SGC/RTV 1600 mg/100 mg once-daily with two NRTIs as a convenient, safe and cost-saving regimen to maintain viral suppression and CD4 counts for 48 weeks in this preselected cohort on highly active antiretroviral therapy (HAART) with pVL <50 copies/mL. The CD4 count rise may be a result of continued immune reconstitution in patients with well-controlled infection.

Development of HIV with Drug Resistance after CD4 Cell Count--Guided Structured Treatment Interruptions in Patients Treated with Highly Active Antiretroviral Therapy after Dual--Nucleoside Analogue Treatment

BACKGROUND

For patients with human immunodeficiency virus (HIV) infection, structured treatment interruption (STI) is an attractive alternative strategy to continuous treatment, particularly in resource-restrained settings, because it reduces both side effects and costs. One major concern, however, is the development of resistance to antiretroviral drugs that can occur during multiple cycles of starting and stopping therapy.

METHODS

HIV genotypic drug resistance was investigated in 20 HIV-infected Thai patients treated with highly active antiretroviral therapy (HAART) and CD4 cell count-guided STI after dual nucleoside reverse-transcriptase inhibitor (NRTI) treatment. Resistance was tested at the time of the switch from dual-NRTI treatment to HAART and when HAART was stopped during the last interruption.

RESULTS

After STI, one major drug-resistance mutation occurred (T215Y), and, in the 4 samples with preexisting major mutations (D67N [n=2], K70R [n=2], T215Y [n=2], and T215I [n=1]), the mutations disappeared. All mutations in the HIV protease gene were minor mutations already present, in most cases, before STI was started, and their frequency was not increased through STI, whereas the frequency of reverse-transcriptase gene mutations significantly decreased after the interruptions. After the 48-week study period, no patients had virological failure. Long-term follow-up (108 weeks) showed 1 case of virological failure in the STI arm and 1 in the continuous arm. No virological failure was seen in patients with major mutations.

CONCLUSIONS

Major HIV drug-resistance mutations were not induced through CD4 cell count-guided treatment interruptions in HIV-infected patients successfully treated with HAART after dual-NRTI therapy.

A Prospective, Randomized Trial of Structured Treatment Interruption for Patients with Chronic HIV Type 1 Infection

BACKGROUND

Structured treatment interruption was evaluated in 74 patients who had been pretreated with antiretrovirals, consisting of 2 nucleoside reverse-transcriptase inhibitors (NRTIs) for 1 year followed by 3 years of highly active antiretroviral therapy containing a protease inhibitor.

METHODS

Patients with a CD4 cell count of > or =350 cells/microL and a plasma viral load of <50 copies/mL were randomized to 3 therapy arms: (1) continuous therapy, (2) CD4 cell count-guided theory, and (3) week-on/week-off (WOWO) therapy. The efficacy and safety of structured treatment interruption and antiretroviral use were evaluated in human immunodeficiency type 1 (HIV-1)-infected patients. The study end points were percentage of patients who developed AIDS or who died and a CD4 cell count of > or =350 cells/microL. Intergroup differences were analyzed using analysis of variance and Kruskal-Wallis tests.

RESULTS

Baseline characteristics at the start of the structured treatment interruption were similar. At week 48, no patient had died, and 1 patient in the WOWO group had an AIDS-defining condition. The proportions of patients with a CD4 cell count of > or =350 cells/microL were 100%, 87%, and 96% in treatment arms 1, 2, and 3, respectively. The percentages of weeks of antiretroviral use were 100%, 41.1%, and 69.8% in arms 1, 2, and 3, respectively. The adverse events were not significantly different among arms (P=.27). Thirty-one percent of patients in the WOWO group experienced virological failure.

CONCLUSION

WOWO therapy maintained a CD4 cell count of > or =350 cells/microL in almost all patients but was associated with high virological failures rates (possibly resulting from previous dual-NRTI therapy), indicating that this strategy is less useful. Receipt of CD4 cell count-guided therapy resulted in comparable clinical outcomes to continuous therapy and may save antiretroviral-associated costs, but this needs to be confirmed by a larger trial.

HIV disease progression in a patient cohort treated via a clinical research network in a resource limited setting

OBJECTIVE

To examine HIV disease progression in a cohort of adult patients treated with antiretroviral therapy (ART) via a clinical research network in Thailand.

DESIGN, SETTING, PARTICIPANTS AND INTERVENTION

A cohort of 417 patients enrolled in a series of randomized ART trials, between 1996 and December 2002.

MAIN OUTCOME MEASURES

Progression to combined endpoint of AIDS defining illness or death according to baseline characteristics, ART used, immunological and virological responses to initial 6 months of ART.

RESULTS

During 1677 person years of follow-up, 29 of 417 patients progressed; tuberculosis was the most common event defining progression (14 of 29 events). The rates of progression to combined endpoint or death alone were 1.7 [95% confidence interval (CI), 1.1-2.4] and 0.7 (95% CI, 0.3-1.3) per 10 person years respectively. Compared to patients with baseline CD4 cell counts > or =350 x 10/l, the adjusted hazard ratio (HR) for progression was 3.67 (95% CI, 1.31-10.27) for patients with <200 x 10 cells/l. Responses to 6 months of therapy were the strongest predictors of disease progression; compared to patients with undetectable viral load at 6 months, HR for progression was 4.95 (95% CI, 2.14-11.46) for viral load >4 log10. Compared to patients with a 6-month CD4 cell count > or =350 x 10/l, HR for progression was 5.22 (95% CI, 1.90-14.37) for patients with <200 x 10 cells/l.

CONCLUSIONS

HIV-infected patients in Thailand who had access to ART, appropriate care, CD4 cell and viral load monitoring facilities via a clinical research network had progression rates comparable to those in developed countries. In this setting, ART initiation could generally be delayed until the CD4 cell count approaches 200 x 10/l.

Pharmacokinetic study of saquinavir hard gel caps/ritonavir in HIV-1-infected patients: 1600/100 mg once-daily compared with 2000/100 mg once-daily and 1000/100 mg twice-daily

OBJECTIVES

A pharmacokinetic comparison of three dosing regimens of saquinavir/ritonavir was carried out: 1600/100 mg once-daily with 1000/100 mg twice-daily, and 1600/100 mg once-daily with 2000/100 mg once-daily.

METHODS

Twenty patients on saquinavir hard gel caps/ritonavir 1600/100 mg once-daily in combination with two nucleoside reverse transcriptase inhibitors for at least 4 weeks were enrolled and randomized to either saquinavir hard gel caps/ritonavir 1000/100 mg twice-daily or 2000/100 mg once-daily. Two pharmacokinetic curves were plotted, at baseline (day 0) and 7 days after the switch. Plasma concentrations were measured at 0, 2, 4, 6, 8, 10, 12 (and 24 for once-daily dosing) hours after drug intake by validated high-performance liquid chromatographic assay (HPLC). The area under the plasma concentration-time curve (AUC0-24 or AUC0-12), maximum and minimum concentration (Cmax and Cmin) and elimination half-life were calculated using a non-compartmental model.

RESULTS

Compared with saquinavir/ritonavir 1600/100 mg once-daily dosing, the saquinavir AUC and Cmin improved significantly when dosed as 1000/100 mg twice-daily (53% and 299%, respectively), and as 2000/100 mg once-daily (71% and 65%, respectively). Low Cmin in three subjects at baseline was corrected after switch to the other dosages. Saquinavir/ritonavir 2000/100 mg once-daily was also associated with a significant increase in saquinavir Cmax (52%) compared with saquinavir/ritonavir 1600/100 mg once-daily.

CONCLUSIONS

Saquinavir/ritonavir when dosed as 2000/100 mg once-daily or 1000/100 mg twice-daily achieves higher saquinavir plasma levels compared with saquinavir/ritonavir 1600/100 mg once-daily. Taking the convenience of once-daily dosing into consideration, dosage of 2000/100 mg once-daily may be preferred.

Antiretroviral treatment in resource-poor settings: what can we learn from the existing programmes in Thailand?

Here we review a number of issues of relevance to the scale-up of antiretroviral therapy in Thailand. Thailand has an estimated number of people living with HIV/AIDS of approximately 600,000. Currently less than 10% of those are receiving highly active antiretroviral therapy. Government commitment to increase the numbers of individuals being treated has increased because of advocacy from various sectors of society, most importantly from organizations of individuals living with HIV/AIDS, decreasing antiretroviral drug prices, the availability of external funds, and the example of successful treatment initiatives by non-governmental organizations, academia and the private sector. It has also been prompted by the hosting of the 2004 International AIDS Conference in Bangkok.

Pharmacokinetics of Lower Doses of Saquinavir Soft-Gel Caps (800 and 1200 Mg Twice Daily) Boosted with Itraconazole in HIV-1-Positive Patients

Objective

The pharmacokinetics of 800 mg and 1200 mg of saquinavir soft-gel caps (SQV-SGC) twice daily plus 100 mg itraconazole once daily were compared to 1400 mg SQV-SGC twice daily without itraconazole.

Methods

The pharmacokinetics of SQV were determined in 17 randomly selected patients on 1400 mg twice daily SQV-SGC without itraconazole and after 2 weeks with lower SQV-SGC doses plus itraconazole. SQV plasma concentrations were determined by HPLC. Pharmacokinetic parameters were calculated by a non-compartmental model.

Results

Median (+IQR) area under plasma concentration-versus-time curve (AUC0–12h) were 3.33 (1.96–7.34), 4.29 (3.14–7.67) and 4.07 (2.76–4.49) mg/l.h for SQV 1400 mg without itraconazole, SQV 1200 mg with itraconazole and SQV 800 mg with itraconazole, respectively. These differences were not statistically significant. The median Cmin was above the proposed minimum effective concentration of 0.05 mg/l for all three regimens.

Conclusion

SQV-SGC 800 mg or 1200 mg twice daily boosted with 100 mg of itraconazole once daily resulted in adequate SQV pharmacokinetics not significantly different from SQV-SGC 1400 mg twice daily.

Pharmacokinetics of once-daily saquinavir hard-gelatin capsules and saquinavir soft-gelatin capsules boosted with ritonavir in HIV-1-infected subjects

OBJECTIVE

To investigate the pharmacokinetics of once-daily saquinavir (SQV) hard-gelatin capsule (HGC)/ritonavir (RTV), 1600/100 mg, compared with once-daily SQV soft-gelatin capsule (SGC)/RTV, 1600/100 mg.

METHODS

We evaluated 13 randomly selected HIV-1-infected subjects taking once-daily SQV SGC/RTV, 1600/100 mg, plus dual nucleoside reverse transcriptase inhibitors (NRTIs) in this pharmacokinetic (PK) substudy. Subjects took 1 week of SQV HGC/RTV and NRTIs, followed by steady-state SQV PK determinations. Subjects then changed to SQV SGC/RTV and NRTIs for 1 week, followed again by steady-state SQV PK determinations. Area under the plasma concentration versus time curve (AUC), maximum concentration (C(max)), minimum concentration (C(min)), time to C(max), and elimination half-life were calculated.

RESULTS

There was no significant difference in AUC values between HGCs and SGCs, with a median (plus interquartile range [IQR]) of 50.0 (42.6-71.5) versus 35.5 (28.0-50.2) mg/L/h, respectively ( =.056). Intersubject variability resulted in 4 of 13 subjects on the SQV SGCs and 2 of 13 subjects on the SQV HGCs having a C(min) below the minimum effective concentration of 0.05 mg/L.

CONCLUSION

Once-daily SQV HGCs, 1600 mg, boosted with once-daily RTV, 100 mg, resulted in PK parameters that were similar to those observed with 1600 mg of SQV SGC/100 mg RTV once daily. Once-daily SQV HGC/RTV, 1600/100 mg, may be easier to use in developing countries and may increase access where drug costs can be less, the capsule size is smaller, and the need for refrigeration is lessened.

Simplifying protease inhibitor therapy with once-daily dosing of saquinavir soft-gelatin capsules/ritonavir (1600/100 mg): HIVNAT 001.3 study

OBJECTIVE

To determine the feasibility of switching therapy for HIV-1-infected patients with plasma viral loads of <50 HIV-1 RNA copies/mL who are receiving twice-daily saquinavir soft-gelatin capsules (SQV-SGC) plus dual nucleoside reverse transcriptase inhibitors (NRTIs) to a regimen containing once-daily SQV-SGC/ritonavir (RTV).

DESIGN

Therapy for patients with plasma viral loads of <50 copies/mL after 2 years of treatment with twice-daily SQV-SGC (1400 mg) plus zidovudine/lamivudine or didanosine/stavudine was switched to once-daily SQV-SGC/RTV (1600/100 mg) with continuing NRTI treatment.

METHODS

Safety and efficacy (determined by plasma viral load and CD4 cell count) were evaluated (week 24). For 12 patients, steady-state plasma pharmacokinetics of SQV was determined (week 4).

RESULTS

Once-daily SQV-SGC/RTV was well tolerated. No patient changed regimens. After 24 weeks, 64 (93%) of 69 patients had plasma viral loads of <50 copies/mL (the remaining 5 patients had plasma viral loads of <300 copies/mL). The median CD4 cell count increased from 534/mL at the start of once-daily SQV-SGCs/RTV to 695/mL after 24 weeks (p <.001). Compared with the preceding 24 weeks of treatment with twice-daily SQV-SGC, the CD4 cell count improved significantly during once-daily SQV-SGC/RTV therapy (p <.001). All patients maintained SQV trough concentrations (C(24h)) of >0.05 mg/L. Median values for the area under the plasma concentration-versus-time curve from 0 to 24 hours (AUC(0-24h)), maximal concentration (C(max)), and C(24h) for SQV were 48.1 (h.mg)/L, 6.98 mg/L, and 0.17 mg/L, respectively. Body weight was inversely correlated with SQV AUC(24h) and C(24h) (p <.01).

CONCLUSIONS

Clinical and pharmacokinetic data support once-daily SQV-SGC/RTV (1600/100 mg) with two NRTIs as a convenient and safe therapeutic regimen to maintain viral suppression and immune function in HIV-1-infected patients with plasma viral loads of <50 copies/mL.

Impact of baseline polymorphisms in RT and protease on outcome of highly active antiretroviral therapy in HIV-1-infected African patients

OBJECTIVE

To assess the therapeutic response and investigate the significance of polymorphic codons in African patients receiving highly-active antiretroviral therapy (HAART).

DESIGN AND METHODS

African patients were identified from the St Mary's Hospital HIV-1 database. Clinical outcome was assessed by viral load and CD4 cell count. Pre- and post-therapy sequences of RT and protease were analysed. The impact of subtype and individual polymorphic codons on therapeutic outcome was assessed statistically (Fishers exact and chi2 tests) and phylogenetically (Jukes and Cantor).

RESULTS

Of 79 drug-naive African patients who were prescribed HAART, 60 remained undetectable for 1 year, with no differences detected in the clinical response to non-nucleoside reverse transcriptase inhibitor (NNRTI)- or protease inhibitor (PI)-containing regimes. Country of origin, sex and viral subtype had no impact on outcome of HAART. A total of 133 polymorphisms were identified in pol (37 in protease and 96 in RT), with a mean of 9.0 in protease and 22.3 in RT per patient. There was no significant difference in the overall numbers of polymorphisms per patient, and no single polymorphism had any impact on clinical outcome. Sequences from 'failing' patients experiencing viral rebound produced few mutations known to be associated with drug resistance, suggesting minimal drug pressure.

CONCLUSIONS

The response of patients infected with African subtypes of HIV-1 to HAART appears to be independent of regime, HIV-1 clade and baseline polymorphisms. Non-B subtypes are fully sensitive to HAART and, accordingly, therapy should not be withheld from African patients for reasons of viral diversity.