PubMed Health⌕ Search

Biomedical subjects

Daniel R Kuritzkes

Publications and source records attributed to Daniel R Kuritzkes.

At least 19 recordsLinked to original sources
PubMed2007

HIV-1 protease and reverse transcriptase mutations for drug resistance surveillance.

OBJECTIVES: Monitoring regional levels of transmitted HIV-1 resistance informs treatment guidelines and provides feedback on the success of HIV-1 prevention efforts. Surveillance programs for estimating the frequency of transmitted resistance are being developed in both industrialized and resource-poor countries. However, such programs will not produce comparable estimates unless a standardized list of drug-resistance mutations is used to define transmitted resistance. METHODS: In this paper, we outline considerations for developing a list of drug-resistance mutations for epidemiologic estimates of transmitted resistance. First, the mutations should cause or contribute to drug resistance and should develop in persons receiving antiretroviral therapy. Second, the mutations should not occur as polymorphisms in the absence of therapy. Third, the mutation list should be applicable to all group M subtypes. Fourth, the mutation list should be simple, unambiguous, and parsimonious. RESULTS: Applying these considerations, we developed a list of 31 protease inhibitor-resistance mutations at 14 protease positions, 31 nucleoside reverse transcriptase inhibitor-resistance mutations at 15 reverse transcriptase positions, and 18 non-nucleoside reverse transcriptase inhibitor-resistance mutations at 10 reverse transcriptase positions. CONCLUSIONS: This list, which should be updated regularly using the same or similar criteria, can be used for genotypic surveillance of transmitted HIV-1 drug resistance.

Anti-HIV Agents↗
PubMed2007

Chemokine antagonists as therapeutics: focus on HIV-1.

Human immunodeficiency virus type 1 (HIV-1) entry into target cells is a multistep process involving the interaction of viral envelope proteins with cell surface receptors. Binding to CD4 is followed by engagement of specific chemokine receptors (CCR5 or CXCR4), triggering molecular rearrangements in the envelope transmembrane subunit that result in membrane fusion. Chemokine receptor antagonists that block the interaction of the HIV-1 envelope with CCR5 or CXCR4 potently inhibit HIV-1 in vitro. Pilot studies of orally bioavailable small-molecule CCR5 inhibitors in HIV-1-infected subjects have provided proof of concept for this novel drug class; phase III safety and efficacy trials are under way.

HIV Fusion Inhibitors↗
PubMed2006

Interruption of enfuvirtide in HIV-1 infected adults with incomplete viral suppression on an enfuvirtide-based regimen.

Many antiretroviral drugs continue to exert an anti-human immunodeficiency virus (HIV) benefit in the presence of drug resistance mutations. The degree to which enfuvirtide exerts continued antiviral activity in the presence of incomplete viral suppression has not been defined. To address this question, 25 subjects interrupted enfuvirtide while remaining on a stable background regimen. Enfuvirtide interruption was associated with an immediate but limited increase in plasma HIV-1 RNA levels. Enfuvirtide resistance waned rapidly in the absence of drug pressure and was no longer detectable by week 16 in most individuals. These data indicate that enfuvirtide has measurable antiviral activity in the setting of incomplete viral suppression. Although enfuvirtide resistance mutations are associated with significant fitness defects in vivo, the clinical significance of these mutations remains undefined.

Adult↗
PubMed2006

Three- vs four-drug antiretroviral regimens for the initial treatment of HIV-1 infection: a randomized controlled trial.

CONTEXT: Three-drug antiretroviral regimens are standard of care for initial treatment of human immunodeficiency virus 1 (HIV-1) infection, but a 4-drug regimen could improve antiretroviral activity and be more effective than a 3-drug regimen. OBJECTIVE: To compare the safety/efficacy of 3-drug vs 4-drug regimens for initial treatment of HIV-1 infection. DESIGN: The AIDS Clinical Trials Group (ACTG) A5095 study, a randomized, double-blind, placebo-controlled study with enrollment and follow-up conducted from March 22, 2001, to March 1, 2005, and enrolling treatment-naive, HIV-1-infected patients with HIV-1 RNA levels of 400 copies/mL or greater from US clinical trials units of the ACTG. INTERVENTIONS: Zidovudine/lamivudine plus efavirenz (3-drug regimen) vs zidovudine/lamivudine/abacavir plus efavirenz (4-drug regimen). MAIN OUTCOME MEASURES: Time to virologic failure (defined as time to first of 2 successive HIV-1 RNA levels > or =200 copies/mL at or after week 16), CD4 cell count changes, and grade 3 or 4 adverse events. HIV-1 RNA data were intent-to-treat, regardless of treatment changes. RESULTS: Seven hundred sixty-five patients with a baseline mean HIV-1 RNA level of 4.86 log10 (72,444) copies/mL and CD4 cell count of 240 cells/mm3 were randomized. After a median 3-year follow-up, 99 (26%) of 382 and 94 (25%) of 383 patients receiving the 3-drug and 4-drug regimens, respectively, reached protocol-defined virologic failure; time to virologic failure was not significantly different (hazard ratio, 0.95; 97.5% confidence interval, 0.69-1.33; P = .73). In planned subgroup analyses, increased risk for virologic failure was seen in non-Hispanic black patients (adjusted hazard ratio, 1.66; 95% confidence interval, 1.18-2.34; P = .003). At 3 years, the HIV-1 RNA level was less than 200 copies/mL in 152 (90%) of 169 and 143 (92%) of 156 patients receiving the 3-drug and 4-drug regimens, respectively (P = .59), and less than 50 copies/mL in 144 (85%) of 169 and 137 (88%) of 156 patients (P = .39). CD4 cell count increases and grade 3 or 4 adverse events were not significantly different. CONCLUSIONS: In treatment-naive patients, there were no significant differences between the 3-drug and 4-drug antiretroviral regimens; overall, at least approximately 80% of patients had HIV-1 RNA levels less than 50 copies/mL through 3 years. These results support current guidelines recommending 2 nucleosides plus efavirenz for initial treatment of HIV-1 infection; adding abacavir as a fourth drug provided no additional benefit. CLINICAL TRIALS REGISTRATION: clinicaltrials.gov Identifier: NCT00013520.

Adult↗
PubMed2006

Pharmacodynamics of antiretroviral agents in HIV-1 infected patients: using viral dynamic models that incorporate drug susceptibility and adherence.

We developed a novel HIV-1 dynamic model with consideration of pharmacokinetics, drug adherence and drug susceptibility to link plasma drug concentration to the long-term changes in HIV-1 RNA observation after initiation of therapy. A Bayesian approach is proposed to fit this model to clinical data from ACTG A5055, a study of two dosage regimens of indinavir (IDV) with ritonavir (RTV) in subjects failing their first protease inhibitor treatment. The HIV RNA testing was completed at days 0, 7, 14, 28, 56, 84, 112, 140, and 168. An intensive pharmacokinetic (PK) evaluation was performed on day 14 and multiple trough concentrations were subsequently collected. Pill counts were used to monitor adherence. IC(50) for IDV and RTV were determined at baseline and at virologic failure. Viral dynamic model fitting residuals were used to assess the significance of covariate effects on long-term virologic response. As univariate predictors, none of the four PK parameters C(trough), C(12 hour), C(max), and AUC was significantly related to virologic response (p > 0.05). By including drug susceptibility (IC(50)), or IC(50) and adherence measured by pill counts together, C(trough), C(12 hour), C(max) and AUC were each significantly correlated to long-term virologic response (p = 0.0055,0.0002,0.0136,0.0002 with IC(50) and adherence measured by pill counts considered). The IC(50) and adherence measured by pill counts alone were not related to the virologic response. In predicting virologic response adherence measured by pill counts did not provide any additional information to PK parameters (p = 0.064), to drug susceptibility IC(50) (p = 0.086), and to their combination (p = 0.22). Simple regression approaches did not detect any significant pharmacodynamic (PD) relationships. Any single factor of PK, adherence measured by pill counts and drug susceptibility did not contribute to long-term virologic response. But their combinations in viral dynamic modeling significantly predicted virologic response. The HIV dynamic modeling can appropriately capture complicated nonlinear relationships and interactions among multiple covariates.

Algorithms↗
PubMed2006

Continued evolution in gp41 after interruption of enfuvirtide in subjects with advanced HIV type 1 disease.

Careful examination of viral dynamics during antiretroviral treatment can provide important insights into HIV pathogenesis. We examined viral evolution during and after enfuvirtide (T-20) treatment with an objective of defining the characteristics of viral evolution during advanced HIV immunodeficiency. Specifically, we examined the viral quasispecies from nine patients who experienced incomplete viral suppression on an enfuvirtide-based regimen, and who subsequently interrupted enfuvirtide while remaining on a stable optimized background regimen (enfuvirtide "partial treatment interruption"). On average, eight clones were sequenced from three time points: pre-enfuvirtide, post-enfuvirtide failure, and post-enfuvirtide interruption. We utilized a Bayesian hierarchical phylogenetic model to assess the evolutionary relatedness of the virus that emerged over time. In most subjects, interruption of enfuvirtide was associated with continued viral evolution as enfuvirtide mutations waned; in no subject did we find clear evidence supporting the reemergence of archived wild-type variants (Bayes factor=30.2, p=0.01). Evidence supporting ongoing viral evolution was particularly strong in subjects whose virus remained diverse or became more diverse during enfuvirtide therapy. In contrast to observations when all drugs are interrupted, loss of resistance during enfuvirtide interruption is most likely due to ongoing viral evolution (and back-mutation), rather than emergence of an archived virus.

Bayes Theorem↗
PubMed2006

Rapid emergence of enfuvirtide resistance in HIV-1-infected patients: results of a clonal analysis.

OBJECTIVES: To study the dynamics of enfuvirtide (T-20) resistance development in HIV-1-infected subjects. PATIENTS AND METHODS: Clonal analysis of gp41 sequences was performed on serial samples obtained from HIV-1-infected subjects with early virologic failure of T-20-based regimens. RESULTS: Enfuvirtide resistance mutations at codons 36 to 45 in the first heptad repeat of gp41 emerged within 2 weeks in most subjects and were associated with the return of plasma HIV-1 RNA level toward baseline by weeks 4 to 8. Mutations at codons 36 (G36E, G36D, or G36S) and 38 (V38A, V38G, or V38M) were the most commonly detected resistance mutations at week 2. Mutations at codons 40 (Q40H) and 43 (N43D) were more prevalent at week 4 than at week 2 and seemed to emerge more slowly than mutations at codons 36 and 38. CONCLUSIONS: The rapid emergence of mutations associated with T-20 resistance in the absence of a fully suppressive antiretroviral regimen demonstrates a low genetic barrier to resistance and underscores the importance of combining T-20 with other active drugs when constructing regimens for highly treatment-experienced patients.

Amino Acid Sequence↗
PubMed2006

Blinded, multicenter comparison of methods to detect a drug-resistant mutant of human immunodeficiency virus type 1 at low frequency.

We determined the abilities of 10 technologies to detect and quantify a common drug-resistant mutant of human immunodeficiency virus type 1 (lysine to asparagine at codon 103 of the reverse transcriptase) using a blinded test panel containing mutant-wild-type mixtures ranging from 0.01% to 100% mutant. Two technologies, allele-specific reverse transcriptase PCR and a Ty1HRT yeast system, could quantify the mutant down to 0.1 to 0.4%. These technologies should help define the impact of low-frequency drug-resistant mutants on response to antiretroviral therapy.

Anti-HIV Agents↗
PubMed2006

Performance of human immunodeficiency virus type 1 gp41 assays for detecting enfuvirtide (T-20) resistance mutations.

The performance of a gp41 assay, created using reagents designed for use with the OpenGene DNA Sequencing System, was evaluated using a panel of plasma samples obtained from enfuvirtide-naive and -experienced human immunodeficiency virus type 1-infected subjects. Resulting sequence data were highly accurate compared to a "home brew" assay and clonal sequence analysis.

Drug Resistance, Viral↗
PubMed2006

Fitness comparison of thymidine analog resistance pathways in human immunodeficiency virus type 1.

Resistance to zidovudine (ZDV) results from thymidine analog resistance mutations (TAMs) at human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) codons 41, 67, 70, 210, 215, and 219. Two mutations are possible at codon 215: Y or F. Whereas T215Y occurs alone or with M41L and L210W (TAM-1 pattern), T215F rarely occurs with these mutations or by itself; it is found instead with D67N, K70R, and K219Q (TAM-2 pattern). The L210W mutation most often occurs with M41L and T215Y and rarely occurs with the T215F or TAM-2 mutation. To explain these associations, TAMs were introduced into HIV-1(Hxb2) by site-directed mutagenesis and expressed in recombinant viruses. Viral replication kinetics, relative fitness, and infectivity were tested in the absence or presence of ZDV. Viruses carrying the 215Y mutation showed faster replication kinetics and greater relative fitness than did T215F mutants in the absence or presence of ZDV. In addition, T215Y mutants showed greater infectivity than did wild-type HIV-1 over a range of ZDV concentrations, but T215F mutants had only a modest advantage over the wild-type virus. Whereas introduction of L210W improved the relative fitness of an M41L/T215Y mutant in the presence of ZDV, introduction of this mutation into a D67N/K70R/K219Q background resulted in decreased relative fitness in the presence or absence of drug. By contrast, introduction of T215F into the D67N/K70R/K219Q background increased viral fitness in the presence of ZDV. These results help explain why T215Y but not T215F usually emerges as the first major TAM, as well as the clustering of L210W with TAM-1 mutations and T215F with TAM-2 mutations.

Amino Acid Substitution↗
PubMed2006

Amdoxovir versus placebo with enfuvirtide plus optimized background therapy for HIV-1-infected subjects failing current therapy (AACTG A5118).

BACKGROUND: Amdoxovir (2,6-diaminopurine dioxolane; DAPD) is a nucleoside reverse transcriptase inhibitor (NRTI) of human immunodeficiency virus-1 (HIV-1) with activity against wild-type and NRTI-resistant viruses. METHODS: ACTG A5118 assessed the antiretroviral activity and safety of DAPD (300 mg orally, twice daily) versus placebo in combination with enfuvirtide (ENF) plus an optimized background (OB) regimen in subjects with failure of two or more antiretroviral (ARV) regimens. The primary endpoints for comparison were time-averaged area under the curve minus baseline (AAUCMB) of plasma HIV-1 RNA concentration at 24 weeks and time to first serious (DAIDS toxicity table Grade > or = 3) adverse event (AE). An unplanned interim review recommended closing enrollment because the study was unlikely to demonstrate a difference between arms. The 18 subjects on study, nine in each arm, were unblinded and allowed to continue study treatment through 48 weeks. RESULTS: Intention-to-treat analysis showed the median AAUCMB was -0.9 log10 copies/mL (95% CI = -2.2, -.0.1) in the DAPD arm and -0.9 log10 copies/ml (95% CI = -1.1, -0.1) in the placebo arm (P = 0.69). Median CD4+ T-cell increase was 79 cells/mm3 (95% CI =1, 115) in the DAPD arm and 60 (95% CI =1, 101) in the placebo arm (P = 0.45). Time to first serious AE did not differ between arms (P = 0.91). Mild decreases of creatinine clearance were observed with similar frequency between arms; no subject developed lens opacities. CONCLUSIONS: Addition of DAPD to ENF plus OB in advanced subjects with highly resistant virus appeared safe, but did not add statistically significant antiretroviral activity at 24 weeks in this small study.

Adult↗
PubMed2005

Pharmacogenetics of plasma efavirenz exposure after treatment discontinuation: an Adult AIDS Clinical Trials Group Study.

BACKGROUND: Efavirenz has a long plasma half-life and a low genetic barrier to resistance. Simultaneously stopping treatment with all agents in efavirenz-containing regimens may result in functional efavirenz monotherapy that selects for drug-resistant human immunodeficiency virus type 1. Lower plasma efavirenz clearance is associated with a cytochrome P450 2B6 gene (CYP2B6) polymorphism (516G-->T) that is more frequent among African American individuals than among European American individuals. METHODS: We characterized relationships between this polymorphism and predicted plasma efavirenz concentration-time profiles after discontinuation of therapy with use of data obtained from subjects receiving therapy. Pharmacokinetic parameters were estimated using population-based methods. Concentrations after discontinuation of therapy were predicted from subject-specific estimates. RESULTS. Median estimated efavirenz half-lives were 23, 27, and 48 h for patients with CYP2B6 position 516 GG (78 patients), GT (60), and TT (14) genotypes, respectively (P<.001). After therapy was stopped, plasma efavirenz concentrations in patients with GG, GT, and TT genotypes were predicted to exceed 46.7 ng/mL (the estimated protein-adjusted 95% inhibitory concentration for wild-type virus) for a median of 5.8 days (interquartile range [IQR], 4.4-8.3 days), 7.0 days (IQR, 5.0-8.0 days), and 14 days (IQR, 11.1-21.2 days), respectively (P<.001). Plasma efavirenz levels were predicted to exceed 46.7 ng/mL for >21 days in 5% of subjects with GG genotype, 5% of subjects with GT genotype, and 29% of subjects with TT genotype. CONCLUSIONS: The CYP2B6 position 516 TT genotype or a prolonged measured elimination half-life may predict increased risk of developing drug resistance among patients who discontinue efavirenz-containing regimens. This has implications for strategies to safely discontinue antiretroviral regimens while avoiding the emergence of drug resistance.

Acquired Immunodeficiency Syndrome↗
PubMed2005

Durable efficacy of enfuvirtide over 48 weeks in heavily treatment-experienced HIV-1-infected patients in the T-20 versus optimized background regimen only 1 and 2 clinical trials.

BACKGROUND: The T-20 Versus Optimized Background Regimen Only (TORO) 1 and TORO 2 clinical trials are open-label, controlled, parallel-group, phase 3 studies comparing enfuvirtide plus an optimized background (OB) of antiretrovirals (n = 661) with OB alone (n = 334) in treatment-experienced HIV-1-infected patients. METHODS: The primary objective at week 48 was to investigate durability of efficacy, as measured by the percentage of patients maintaining their week 24 response or improving. Efficacy analyses used the intent-to-treat population. RESULTS: A total of 73.7% of patients randomized to the enfuvirtide group remained on treatment through week 48 versus 21.3% originally randomized to the control group. At week 48, a higher proportion of week 24 responders maintained their response or were new responders in the enfuvirtide group than in the control group in each responder category: HIV-1 RNA level > or =1.0 log(10) change from baseline, <400 copies/mL and <50 copies/mL (37.4%, 30.4%, and 18.3% in the enfuvirtide group vs. 17.1%, 12.0%, and 7.8% in the control group, respectively; P < 0.0001 for all comparisons). CD4 cell count increases from baseline were twice as great in the enfuvirtide group as in the control group. CONCLUSION: These data demonstrate durable efficacy of enfuvirtide plus OB over 48 weeks.

Adolescent↗