Virologic response to nelfinavir-based regimens: pharmacokinetics and drug resistance mutations (VIRAPHAR study).
OBJECTIVE
To assess the impact of HIV-1 protease and reverse transcriptase (RT) mutations, and pharmacokinetic parameters on virological responses to nelfinavir (NFV)-containing highly active antiretroviral therapy.


METHODS
Naive or antiretroviral-experienced HIV-1-infected subjects were included in a non-randomized, observational cohort study and received two nucleoside RT inhibitors + NFV (750 mg three times per day or 1250 mg twice per day). Virologic success was defined as a virus load < 50 copies/ml for > 6 months.


METHODS
RT and protease genes were sequenced at baseline and at the time of virological failure. Plasma NFV trough concentration (Cmin), maximum concentration (Cmax), and AUC0-tau at steady-state were subjected to population pharmacokinetic analysis.


RESULTS
Patients (n = 154) enrolled between November 1998 and February 2000 started a twice per day (n = 84) or three times per day (n = 70) NFV-based regimen as first- (n = 48) or second-line therapy when protease inhibitor-naive (n = 64) or -experienced (n = 42). Median follow-up duration was 16 months. Virologic failure occurred in 88 patients. No significant differences were observed between twice per day and three times per day regimens. According to multivariate analysis, NFV Cmin and Cmax, CD4 cell count, number of baseline RT + protease gene mutations, D67N, M184V, T215F/Y in RT, and M36I in protease, were independent factors that were significantly predictive of failure. At failure, L10I, D30N, M36I, V77I, N88S/D or L90M protease mutations had emerged since baseline. Pharmacokinetic parameters were similar in patients with or without emergence of these neo-mutations. The more discriminating NFV Cmin efficacy-threshold was estimated to be 1 mg/l.


CONCLUSIONS
Our data confirm the association among individual pharmacokinetic parameters, genotype pattern and virological response to NFV-containing regimens.
Department of Virology, Bordeaux University Hospital, Bordeaux, France.
Isabelle
I
Pellegrin
Dominique
D
Breilh
François
F
Montestruc
Anne
A
Caumont
Isabelle
I
Garrigue
Philippe
P
Morlat
Cécile
C
Le Camus
Marie-Claude
MC
Saux
Hervé J A
HJ
Fleury
Jean-Luc
JL
Pellegrin
D000328:Adult; D019380:Anti-HIV Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D023241:Antiretroviral Therapy, Highly Active; D018791:CD4 Lymphocyte Count; D015331:Cohort Studies; D024882:Drug Resistance, Viral / Q000235:genetics*; D004359:Drug Therapy, Combination; D005260:Female; D005838:Genotype; D015658:HIV Infections / Q000188:drug therapy* / Q000378:metabolism / Q000821:virology; D016333:HIV Protease / Q000235:genetics; D017320:HIV Protease Inhibitors / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D009154:Mutation; D019888:Nelfinavir / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D012194:RNA-Directed DNA Polymerase / Q000235:genetics; D018894:Reverse Transcriptase Inhibitors / Q000493:pharmacokinetics / Q000627:therapeutic use
D019380:Anti-HIV Agents; D017320:HIV Protease Inhibitors; D018894:Reverse Transcriptase Inhibitors; D012194:RNA-Directed DNA Polymerase; D016333:HIV Protease; D019888:Nelfinavir