Christoph Wyen

Impact of CYP2B6 983T>C polymorphism on non-nucleoside reverse transcriptase inhibitor plasma concentrations in HIV-infected patients

OBJECTIVES The aim of this study was to investigate the frequency of CYP2B6 polymorphisms (according to ethnicity) and the influence of heterozygosity and homozygosity on plasma concentrations of efavirenz and nevirapine. METHODS Following written informed consent, 225 Caucasians and 146 Blacks were recruited from the German Competence Network for HIV/AIDS. Plasma concentrations of efavirenz and nevirapine were assessed by HPLC, and genotyping for 516G>T, 983T>C and 1459T>C polymorphisms in CYP2B6 was conducted by real-time PCR-based allelic discrimination. RESULTS The minor allele frequency for 516G>T, 983T>C and 1459T>C was 0.29, 0 and 0.08 in Caucasians and 0.34, 0.07 and 0.02 in Blacks, respectively. Two Black patients with the 983C allele receiving efavirenz were identified and both were withdrawn from therapy within 1 week of sampling due to toxicity. In multivariate analyses, efavirenz and nevirapine plasma concentrations were significantly associated with 983T>C (P < 0.0001 and P = 0.02, respectively), 516G>T (P < 0.0001 and P = 0.002, respectively) and time of drug analysis post-dose (P < 0.0001 for both). Body mass index was independently related to efavirenz (P = 0.04) but not nevirapine concentrations, and age was related to nevirapine (P = 0.05) but not efavirenz concentrations. Consistent with other studies, 1459C>T was not associated with plasma concentrations of either drug (P > 0.05 for both drugs). CONCLUSIONS This is the first report that the 983T>C genotype (part of the CYP2B6*18 haplotype) impacts on nevirapine plasma concentrations and the first study to assess the impact of 983C homozygosity on efavirenz concentrations. These data have implications for administration of non-nucleoside reverse transcriptase inhibitors to Black patients.

Cytochrome P450 2B6 (CYP2B6) and constitutive androstane receptor (CAR) polymorphisms are associated with early discontinuation of efavirenz-containing regimens

OBJECTIVES Cytochrome P450 2B6 (CYP2B6) is responsible for the metabolic clearance of efavirenz and single nucleotide polymorphisms (SNPs) in the CYP2B6 gene are associated with efavirenz pharmacokinetics. Since the constitutive androstane receptor (CAR) and the pregnane X receptor (PXR) correlate with CYP2B6 in liver, and a CAR polymorphism (rs2307424) and smoking correlate with efavirenz plasma concentrations, we investigated their association with early (<3 months) discontinuation of efavirenz therapy. METHODS Three hundred and seventy-three patients initiating therapy with an efavirenz-based regimen were included (278 white patients and 95 black patients; 293 male). DNA was extracted from whole blood and genotyping for CYP2B6 (516G → T, rs3745274), CAR (540C → T, rs2307424) and PXR (44477T → C, rs1523130; 63396C → T, rs2472677; and 69789A → G, rs763645) was conducted. Binary logistic regression using the backwards method was employed to assess the influence of SNPs and demographics on early discontinuation. RESULTS Of the 373 patients, 131 withdrew from therapy within the first 3 months. Black ethnicity [odds ratio (OR) = 0.27; P = 0.0001], CYP2B6 516TT (OR = 2.81; P = 0.006), CAR rs2307424 CC (OR = 1.92; P = 0.007) and smoking status (OR = 0.45; P = 0.002) were associated with discontinuation within 3 months. CONCLUSIONS These data indicate that genetic variability in CYP2B6 and CAR contributes to early treatment discontinuation for efavirenz-based antiretroviral regimens. Further studies are now required to define the clinical utility of these associations.

Antibody 10-1074 suppresses viremia in HIV-1-infected individuals

Monoclonal antibody 10-1074 targets the V3 glycan supersite on the HIV-1 envelope (Env) protein. It is among the most potent anti-HIV-1 neutralizing antibodies isolated so far. Here we report on its safety and activity in 33 individuals who received a single intravenous infusion of the antibody. 10-1074 was well tolerated and had a half-life of 24.0 d in participants without HIV-1 infection and 12.8 d in individuals with HIV-1 infection. Thirteen individuals with viremia received the highest dose of 30 mg/kg 10-1074. Eleven of these participants were 10-1074-sensitive and showed a rapid decline in viremia by a mean of 1.52 log10 copies/ml. Virologic analysis revealed the emergence of multiple independent 10-1074-resistant viruses in the first weeks after infusion. Emerging escape variants were generally resistant to the related V3-specific antibody PGT121, but remained sensitive to antibodies targeting nonoverlapping epitopes, such as the anti-CD4-binding-site antibodies 3BNC117 and VRC01. The results demonstrate the safety and activity of 10-1074 in humans and support the idea that antibodies targeting the V3 glycan supersite might be useful for the treatment and prevention of HIV-1 infection.

Progressive Multifocal Leukencephalopathy in Patients on Highly Active Antiretroviral Therapy: Survival and Risk Factors of Death

ObjectiveTo describe the clinical course and risk factors of death in highly active antiretroviral therapy (HAART)-treated patients with progressive multifocal leukencephalopathy (PML); to evaluate the efficacy of cidofovir in addition to HAART. MethodsRetrospective multicenter cohort study of PML in HIV-1–infected patients. Diagnosis of PML was confirmed by histology or by positive polymerase chain reaction for JC virus (JCV) in cerebrospinal fluid (CSF) or was made by typical radiologic and clinical findings. ResultsThirty-five cases of PML were identified. The diagnosis was made by histology (9 cases), detection of JCV in CSF (17 cases), and by radiologic findings (9 cases). Upon manifestation of PML, 15/35 patients had never received HAART, and 11/35 were on HAART for >6 months (median 1126 days). In 9/35 cases, clinical manifestation of PML occurred within 6 months after initiation of HAART. All patients received HAART after PML diagnosis. After a median follow-up of 553 days (range 28–2694 days), the median survival time was not reached. In 12 patients who were treated concomitantly with cidofovir, cumulative survival was significantly shorter than in patients without cidofovir (P = 0.03). Patients in whom PML was diagnosed while on HAART demonstrated a trend toward a shorter survival than HAART-naive patients (P = 0.15). ConclusionsPML continues to occur in HIV-1–infected patients even when they are treated with HAART. Patients developing PML on HAART had a trend toward a shorter median survival compared with treatment-naive patients, and cidofovir therapy was not associated with improved survival in this cohort.

Improved outcome with rituximab in patients with HIV-associated multicentric Castleman disease

Although HIV-associated multicentric Castleman disease (HIV-MCD) is not classified as an AIDS-defining illness, mortality is high and progression to lymphoma occurs frequently. At present, there is no widely accepted recommendation for the treatment of HIV-MCD. In this retrospective (1998-2010), multicentric analysis of 52 histologically proven cases, outcome was analyzed with respect to the use of different MCD therapies and potential prognostic factors. After a mean follow-up of 2.26 years, 19 of 52 patients died. Median estimated overall survival (OS) was 6.2 years. Potential risk factors, such as older age, previous AIDS, or lower CD4 T cells had no impact on OS. Treatment was heterogeneous, consisting of cytostatic and/or antiviral agents, rituximab, or combinations of these modalities. There were marked differences in the outcome when patients were grouped according to MCD treatment. Patients receiving rituximab-based regimens had higher complete remission rates than patients receiving chemotherapy only. The mean estimated OS in patients receiving rituximab alone or in combination with cytostatic agents was not reached, compared with 5.1 years (P = .03). Clinical outcome and overall survival of HIV-MCD have markedly improved with rituximab-based therapies, considering rituximab-based therapies (with or without cytostatic agents) to be among the preferred first-line options in patients with HIV-MCD.

Stage-Adapted Treatment of HIV-Associated Hodgkin Lymphoma: Results of a Prospective Multicenter Study

PURPOSE Although the outcome of patients with HIV-related Hodgkin lymphoma (HIV-HL) has markedly improved since the introduction of combined antiretroviral therapy, standard therapy is still poorly defined. This prospective study investigates a stage- and risk-adapted treatment strategy in patients with HIV-HL. PATIENTS AND METHODS Patients with early favorable HIV-HL received two to four cycles of doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) followed by 30 Gy of involved-field (IF) radiation. In patients with early unfavorable HIV-HL, four cycles of bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone (BEACOPP baseline) or four cycles of ABVD + 30 Gy of IF radiation were administered. Six to eight cycles of BEACOPP baseline were given in patients with advanced-stage HIV-HL. In patients with advanced HIV infection, BEACOPP was replaced with ABVD. RESULTS Of 108 patients (including eight female patients) included in the study, 23 (21%) had early favorable HL, 14 (13%) had early unfavorable HL, and 71 (66%) had advanced-stage HL. The median CD4 count at HL diagnosis was 240/μL. The complete remission rates for patients with early favorable, early unfavorable, and advanced-stage HL were 96%, 100%, and 86%, respectively. The 2-year progression-free survival of the entire study population was 91.7%. Eleven patients (11%) have died, and treatment-related mortality was 5.6%. The 2-year overall survival rate was 90.7% with no significant difference between early favorable (95.7%), early unfavorable (100%), and advanced-stage HL (86.8%). CONCLUSION In patients with HIV-HL, stage- and risk-adapted treatment is feasible and effective. The prognosis for patients with HIV-HL may approach that of HIV-negative patients with HL.

Effect of an Antiretroviral Regimen Containing Ritonavir Boosted Lopinavir on Intestinal and Hepatic CYP3A, CYP2D6 and P‐glycoprotein in HIV‐infected Patients

This study aimed to quantify the inhibition of cytochrome P450 (CYP3A), CYP2D6, and P‐glycoprotein in human immunodeficiency virus (HIV)‐infected patients receiving an antiretroviral therapy (ART) containing ritonavir boosted lopinavir, and to identify factors influencing ritonavir and lopinavir pharmacokinetics. We measured activities of CYP3A, CYP2D6, and P‐glycoprotein in 28 patients before and during ART using a cocktail phenotyping approach. Activities, demographics, and genetic polymorphisms in CYP3A, CYP2D6, and P‐glycoprotein were tested as covariates. Oral midazolam clearance (overall CYP3A activity) decreased to 0.19‐fold (90% confidence interval (CI), 0.15–0.23), hepatic midazolam clearance and intestinal midazolam availability changed to 0.24‐fold (0.20–0.29) and 1.12‐fold (1.00–1.26), respectively. In CYP2D6 extensive metabolizers, the plasma ratio AUCdextromethorphan/AUCdextrorphan increased to 2.92‐fold (2.31–3.69). Digoxin area under the curve (AUC)0–12 (P‐glycoprotein activity) increased to 1.81‐fold (1.56–2.09). Covariates had no major influence on lopinavir and ritonavir pharmacokinetics. In conclusion, CYP3A, CYP2D6, and P‐glycoprotein are profoundly inhibited in patients receiving ritonavir boosted lopinavir. The covariates investigated are not useful for a priori dose selection.

Integration of population pharmacokinetics and pharmacogenetics: an aid to optimal nevirapine dose selection in HIV-infected individuals

Background Nevirapine is metabolized by CYP2B6 and polymorphisms within the CYP2B6 gene partly explain inter-patient variability in pharmacokinetics. The aim of this study was to model the complex relationship between nevirapine exposure, weight and genetics (based on combined analysis of CYP2B6 516G > T and 983T > C single nucleotide polymorphisms). Methods Non-linear mixed-effects modelling was used to estimate pharmacokinetic parameters from 275 patients. Simulations of the nevirapine concentration profile were performed with dosing regimens of 200 mg twice daily and 400 mg once daily for individuals with body weights of 50, 70 and 90 kg in combination with CYP2B6 genetic variation. Results A one-compartment model with first-order absorption best described the data. Population clearance was 3.5 L/h with inter-patient variability of 24.6%. 516T homozygosity and 983C heterozygosity were associated with 37% and 40% lower clearance, respectively. Body weight was the only significant demographic factor influencing clearance, which increased by 5% for every 10 kg increase. For individuals with higher body weight, once-daily nevirapine was associated with a greater risk of sub-therapeutic drug exposure than a twice-daily regimen. This risk was offset in individuals who were 516T homozygous or 983C heterozygous in which drug exposure was optimal for  > 95% of patients with body weight of ≤70 kg. Conclusions The data suggest that a 400 mg once-daily dose could be implemented in accordance with CYP2B6 polymorphism and body weight. However, the use of nevirapine once daily (immediate release; off-label) in the absence of therapeutic drug monitoring is not recommended due to the risk of inadequate exposure to nevirapine in a high proportion of patients. There are different considerations for the extended-release formulation (nevirapine XR) that demonstrate minimal peak-to-trough fluctuations in plasma nevirapine levels.

AIDS-related B-cell lymphoma (ARL): correlation of prognosis with differentiation profiles assessed by immunophenotyping.

This study was undertaken to analyze the differentiation profiles assessed by immunophenotyping in AIDS-related B-cell lymphoma (ARL) and their relation to the clinical course. Paraffin-embedded sections of 89 ARL cases during 1989 to 2004 were stained immunohistochemically with antibodies to CD3, CD10, CD20, CD38, CD138/Syndecan-1 (Syn-1), multiple myeloma-1/interferon regulatory factor-4 (MUM1/IRF4), B-cell lymphoma protein-2 (BCL-2), BCL-6, latent membrane protein-1 (LMP-1), and Ki-67. Expression of CD10 and CD20 were associated with better overall survival (OS; P = .009 and P = .04, respectively). Expression of CD20 was associated with longer disease-free survival (DFS; P = .03), whereas expression of CD138/Syn-1 was associated with shorter DFS (P = .03). OS and DFS were worse in patients with immunophenotypic profiles related to post-germinal center (GC) differentiation (BCL-6 and CD10 negative, MUM1/IRF4 and/or CD138/Syn-1 positive) when compared with GC differentiation (P = .01). When controlled for age-adjusted International Prognostic Index (IPI), prior AIDS-defining illness (ADI), and year of ARL diagnosis, a post-GC differentiation remained significantly associated with poor OS and DFS. Expression of CD10 was associated with a preserved immunocompetence, whereas CD20 was less frequent in patients developing ARL while on highly active antiretroviral therapy (P = .04). In summary, lack of CD20 or CD10 expression and a post-germinal center signature are associated with a worse prognosis in ARL.

Pharmacokinetic and Pharmacodynamic Analysis of Efavirenz Dose Reduction Using an In Vitro–In Vivo Extrapolation Model

The pharmacokinetics (PK) of efavirenz (EFV) is characterized by marked interpatient variability that correlates with its pharmacodynamics (PD). In vitro–in vivo extrapolation (IVIVE) is a “bottom‐up” approach that combines drug data with system information to predict PK and PD. The aim of this study was to simulate EFV PK and PD after dose reductions. At the standard dose, the simulated probability was 80% for viral suppression and 28% for central nervous system (CNS) toxicity. After a dose reduction to 400 mg, the probabilities of viral suppression were reduced to 69, 75, and 82%, and those of CNS toxicity were 21, 24, and 29% for the 516 GG, 516 GT, and 516 TT genotypes, respectively. With reduction of the dose to 200 mg, the probabilities of viral suppression decreased to 54, 62, and 72% and those of CNS toxicity decreased to 13, 18, and 20% for the 516 GG, 516 GT, and 516 TT genotypes, respectively. These findings indicate how dose reductions might be applied in patients with favorable genetic characteristics.