Genetics plays a limited role in predicting chronic obstructive pulmonary disease treatment response and exacerbation.

BACKGROUND: Combination treatments, targeting multiple disease processes, benefit subjects with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). However, predicting treatment response and exacerbation risk remain challenging. OBJECTIVE: To identify genetic associations with AECOPD risk and response to combination therapy (fluticasone furoate, umeclidinium bromide and vilanterol). METHODS: The genetic basis of AECOPD disease was investigated in 19,841 subjects from 23 clinical studies and 2 disease cohorts to identify exacerbation disease targets. AECOPD pharmacogenetic effects were examined in 8439 moderate to severe COPD patients with exacerbation rate, lung function and quality of life endpoints; results were followed up in an additional 2201 subjects. RESULTS: We did not identify significant associations in the AECOPD disease analysis. In the AECOPD pharmacogenetics analysis, rs56195836 (MAPK8) was significantly associated with moderate to severe exacerbation rate in subjects on fluticasone furoate with baseline blood eosinophils ≥150 cells/µl (P = 1.8 × 10-8). Post-hoc, one variant was associated with on-treatment moderate to severe exacerbation rate stratifying by exacerbation history. AZU1 rs1962343 was significantly associated in subjects with frequent moderate exacerbation history when treated with fluticasone furoate/vilanterol (P = 1.1 × 10-8). Neither of these signals was supported in independent follow-up. CONCLUSION: Common genetic variants do not play major roles in AECOPD disease nor predict response to triple therapy or its components in moderate to very severe COPD.

Pharmacogenetic investigation of efficacy response to mepolizumab in eosinophilic granulomatosis with polyangiitis.

Treatment of patients with the rare disease eosinophilic granulomatosis with polyangiitis (EGPA) with mepolizumab, a monoclonal antibody to interleukin-5 (IL-5) that reduces blood eosinophil counts, as an add-on therapy to glucocorticoid treatment, results in more accrued weeks in remission, reductions in glucocorticoid use and reductions in relapse rate. However, treatment response varies across a continuum. Therefore, to investigate if large genetic effects could identify responders, the impact of genetic variants on efficacy in EGPA subjects taking mepolizumab and glucocorticoids was assessed in this post hoc study. Using linear regression and a negative binomial model, genetic variant association with three endpoints (accrued duration of remission, average oral glucocorticoid dose, and frequency of relapse) was tested in 61 EGPA subjects dosed with mepolizumab from MIRRA, a phase 3 trial. Candidate gene and genome-wide approaches were used. The candidate gene analysis was designed to investigate drug target effects with eight gene regions selected that were focused on the intersection of the glucocorticoid response (steroidal response) and IL-5 response mechanisms and recognizing potential overlap between EGPA and severe eosinophilic asthma diseases for which mepolizumab is used. The sample size was insufficient to enable testing of rare variants for effects. No genetic variant from either the candidate gene analysis or the GWAS associated with any endpoint. Thresholds to declare significance were p < 0.0008 (candidate variant) and p < 2.5 × 10-8 (genome-wide) analyses. Large genetic effects on mepolizumab-treatment response were not identified which could help differentiate responders from non-responders.

Genetic effects on efficacy to fluticasone propionate/salmeterol treatment in COPD.

PURPOSE: No studies have investigated genetic effects on quality of life (QoL) measurements like improvements in the St George's Respiratory Questionnaire (SGRQ) scores for chronic obstructive pulmonary disease treatments with fluticasone propionate/salmeterol (FSC). Therefore, in addition to testing genetic effects on change from baseline in trough forced expiratory volume in 1 s (FEV1), genetic associations that may predict SGRQ response to FSC treatment were investigated in this analysis. METHODS: This post hoc exploratory genome-wide genetic analysis included subjects from 10 clinical trials: NCT01772134, NCT01772147, NCT00633217, NCT01817764, NCT01879410, NCT01822899, NCT01323621, NCT01342913, NCT01323634, and NCT01706328. The Genetics Analysis Population (subjects who provided written consent, a blood sample for genetic research, and were successfully genotyped) included 2005/2900 subjects in the intent-to-treat sample, who received FSC, for testing association with change from baseline in trough FEV1 and 1188/2005 subjects for testing SGRQ responses (change from baseline SGRQ score and categorical response by SGRQ score with Responders achieving >4 unit decrease at end of study treatment). MAIN FINDINGS: One locus on chromosome 20 with seven variants with low minor allele frequencies significantly associated with change from baseline SGRQ score. The binary SGRQ response provided similar trends for association but did not attain genome-wide significance levels. No genetic association was detected with change from baseline in trough FEV1. CONCLUSIONS: Common variants are unlikely to play a role in response to FSC.

No genetic associations with mepolizumab efficacy in COPD with peripheral blood eosinophilia.

INTRODUCTION: Improved understanding of genetic effects on response to treatments with novel approaches for COPD with peripheral blood eosinophilia, such as mepolizumab (a humanized monoclonal antibody to IL-5), may improve treatment outcomes. We conducted a study to identify genetic variants associated with efficacy of mepolizumab COPD. MATERIALS AND METHODS: Using generalized linear and logistic regression models, genome-wide association analyses were performed to investigate genetic associations with frequency of moderate and/or severe COPD exacerbations in COPD subjects receiving mepolizumab (weeks 0-52). Additional analyses included: (i) frequency of COPD exacerbations requiring hospitalization or emergency department visit (weeks 0-52), (ii) change from baseline mean total St. George's Respiratory Questionnaire (SGRQ) score (week 24), and (iii) SGRQ response defined as achieving a 4 unit or greater decrease of SGRQ score from baseline (week 24). This study included 610 patients with COPD, a subset of the Intent-to-treat (ITT) populations in two phase III double-blind trials assessing the efficacy and safety of mepolizumab, METREX (NCT02105948) and METREO (NCT02105961). All subjects had elevated eosinophil levels (≥150 cells/µL at screening or ≥300 cell/µL in the 12 months prior to study), were treated with mepolizumab, and provided consent for genetic analysis. RESULTS: From this post-hoc analysis, no genetic variant was significantly associated with moderate and/or severe COPD exacerbations or any of the other endpoints tested (threshold for statistical significance at the genome-wide level, p = 5 × 10-8). CONCLUSIONS: In this exploratory study in patients with COPD, with peripheral blood eosinophilia, no genetic effects on mepolizumab-treatment response were identified.

No genetic association detected with mepolizumab efficacy in severe asthma.

BACKGROUND AND OBJECTIVES: Treatment with mepolizumab, a humanized monoclonal antibody to interleukin-5, reduces the rate of asthma exacerbations and the requirement for systemic glucocorticoids while maintaining asthma control. Treatment decisions are guided by predictors of response, including blood eosinophil thresholds in patients with frequent exacerbations despite intensive anti-inflammatory and controller treatment. Identification of additional predictors of response could aid treatment decisions. We investigated genetic associations that may predict response to mepolizumab-treatment. METHODS: In this post hoc analysis of DREAM and MENSA, association of genetic markers was tested in patients with severe asthma treated with mepolizumab who provided consent for pharmacogenetic research. Association was tested in a tiered approach with alpha spend differing for candidate genetic markers selected for prior history of association with relevant traits or pathways and in a genome-wide analyses (p < 4.7 × 10-4 and p < 5 × 10-8, respectively). Efficacy endpoints included: clinically significant exacerbation rate (tested using a negative binomial model), time to first exacerbation (tested with a Cox proportional hazards model), change in exacerbation rate, change in eosinophil count, and change in IgE level (tested by linear regression). RESULTS: No genetic marker was significantly associated with the primary endpoint, clinically significant exacerbation rate. One genetic marker was associated with time to first clinically significant exacerbation, but this association was driven by the DREAM data and was not supported in additional sensitivity analyses by treatment regimen/dose. CONCLUSION: No genetic effect on mepolizumab-treatment response was identified in this population on intensive asthma treatment, with history of frequent exacerbations and pre-selected for airway eosinophilia.

Genetic effects on treatment response of umeclidinium/vilanterol in chronic obstructive pulmonary disease.

BACKGROUND: Treatment with long-acting ß2-agonists (LABAs) and long-acting muscarinic antagonists (LAMAs) for chronic obstructive pulmonary disease (COPD) is standard, but response varies. We investigated genetic association with treatment response to umeclidinium (UMEC, a LAMA), vilanterol (VI, a LABA), and combination therapy. METHODS: Data from 17 clinical trials (N = 6075) in patients with COPD receiving once-daily UMEC/VI (125/25mcg or 62.5/25mcg), UMEC (125 or 62.5mcg), VI (25mcg) or placebo were used. Genetic association with change from baseline in trough forced expiratory volume in 1 s (FEV1) ∼24 h post-dosing was assessed for: (i) 3 ß2-adrenoceptor (ADRB2) gene variants; (ii) 298 single-nucleotide polymorphisms (SNPs) with prior evidence of associations; (iii) human leukocyte antigen (HLA) alleles and (iv) genome-wide association study (GWAS) SNPs. Other endpoints were (i) reversibility at screening; and at baseline: (ii) FEV1; (iii) forced vital capacity (FVC), and (iv) FEV1/FVC ratio. Using linear regression, the inverse normal transformed residuals were pooled together, first across treatment group, then across studies for each monotherapy, then combination therapy and finally for every treated patient. RESULTS: Of 6075 patients, 1849 received UMEC/VI, 1390 received UMEC, 1795 received VI, and 1041 received placebo. None of the ADRB2 variants, HLA alleles or GWAS variants tested were associated with treatment response or baseline endpoints. Four SNPs in FAM13A (rs7671167, rs2869967, rs1964516, rs1903003) were significantly associated with baseline FEV1/FVC ratio (p < 3 × 10(-5)) after adjusting for multiple testing. CONCLUSIONS: No genetic association was found with treatment response to UMEC or VI when administered as monotherapies or in combination.

Exploring the roles of UGT1A1 and UGT1A3 in oral clearance of GSK2190915, a 5-lipoxygenase-activating protein inhibitor.

Pharmacokinetic variability in drug exposure is a concern for all compounds in development including those for the treatment of asthma and other respiratory disorders. Substantial variability in the oral clearance of GSK2190915, a 5-lipoxygenase-activating protein inhibitor that attenuates the production of leukotriene B4 and cysteinyl leukotrienes, is largely unaccounted for by clinical variables. A study of 41 patients, 78% (32/41) of whom were non-Hispanic whites, with mild to moderate asthma identified an association of UGT1A1*28 and UGT1A3*2 with the oral clearance of GSK2190915 (P=3.8×10⁻4 and 1.2×10⁻5, respectively). However, in a subsequent replication study of 403 non-Hispanic white patients with asthma, we failed to observe a statistically significant association between oral clearance of GSK2190915 and either UGT1A1*28 or UGT1A3*2 (P>0.05). Therefore, genetic effects that could explain the systemic exposure level variability of GSK2190915 were not identified.

Safety and efficacy of epelsiban in the treatment of men with premature ejaculation: a randomized, double-blind, placebo-controlled, fixed-dose study.

AIM: To assess the efficacy and safety of the selective oxytocin receptor antagonist epelsiban in the treatment of premature ejaculation (PE). METHODS: Double-blind, randomized, parallel-group, placebo-controlled, stopwatch-monitored, phase 2, multicenter study (GSK557296; NCT01021553) conducted in men (N=77) 18-55 years of age, with PE defined as per International Society for Sexual Medicine consensus definition. Patients provided informed consent prior to a 4-week un-medicated run-in to determine baseline intravaginal ejaculatory latency times (IELT) recorded in an electronic diary. Patients needed to make a minimum of four intercourse attempts and have a mean IELT<65 seconds to be considered for randomization. Men with moderate-to-severe erectile dysfunction were excluded from the study. Eligible patients were randomized to placebo, epelsiban 50 mg, or 150 mg, taken 1 hour before sexual activity. Active treatment IELT times were recorded in an electronic diary, along with subjective measures of intercourse satisfaction, over an 8-week treatment period. The Modified Index of Premature Ejaculation and International Index of Erectile Function were completed at study visits. MAIN OUTCOME MEASURES: Stopwatch timed IELT recordings and a modified version of the patient-reported outcome questionnaire the IPE were used in this study to determine the effect of epelsiban when taken orally prior to intercourse in subjects diagnosed with PE. RESULTS: The baseline (mean) IELT for patients pretreatment was (0.52, 0.63, and 0.59 minutes) for placebo, epelsiban 50 mg and 150 mg, respectively. On-treatment, average geometric least squares means of the median IELT values (mean) were slightly higher in the 50 mg and 150 mg groups (0.72 and 0.69 minutes), respectively, vs. the placebo group (0.62 minutes). Headache was the most common adverse event, and rates were similar across all groups. CONCLUSIONS: Epelsiban 50 mg and 150 mg were well tolerated, but did not result in a clinically or statistically significant change in IELT in men with PE, compared with placebo.

Genetic analysis of asthma exacerbations.

BACKGROUND: Identifying genetic markers of susceptibility to exacerbations may improve patient management, decrease morbidity, and lead to drug development. OBJECTIVES: To assess whether genetic markers associated with severe asthma exacerbations in previous reports are associated with less severe events that do not require intensive care and intubation and to identify additional markers in candidate genes and throughout the genome. METHODS: A total of 199 patients and 502 controls (individuals without an exacerbation) were identified from 4 clinical trials. We genotyped 51 markers from 17 genes previously reported to be associated with exacerbations; a whole genome scan was used to identify additional markers. Admixture analysis was conducted to characterize the presence of ancestral groups. The genetic marker effects were assessed by logistic regression for each study followed by a meta-analysis. RESULTS: Several coding variants in the IL4R gene had a genetic effect across 3 studies, including rs1805011 in IL4R (P < .0006). In addition, 3 markers in the IFNB1 gene showed evidence of association (P < .002) but only in the study with African Americans. Because these markers did not meet the prespecified multiplicity-adjusted significance level of P = .0002, we were unable to confirm previously published results for less severe events. The whole genome scan identified genes related to mast cell mediator release. The admixture analysis suggests that ancestry was best characterized by the presence of 3 ancestral groups. CONCLUSION: We were unable to confirm previously reported associations of genetic markers with asthma exacerbations. Although, in general, the patients studied had less severe asthma than patients in earlier reports, these results suggest involvement of similar pathways. TRIAL REGISTRATION: clinicaltrials.gov Identifiers: NTC00452699, NCT00452348, NTC00102765, NCT00843193.

Genome-wide association study identifies genetic determinants of urine PCA3 levels in men.

Prostate cancer gene 3 (PCA3) is a non-coding gene specifically overexpressed in prostate cancer (PCa) that has great potential as a clinical biomarker for predicting prostate biopsy outcome. However, genetic determinants of PCA3 expression level remain unknown. To investigate the association between genetic variants and PCA3 mRNA level, a genome-wide association study was conducted in 1371 men of European descent in the REduction by DUtasteride of prostate Cancer Events trial. First-voided urine specimens containing prostate cells were obtained after digital rectal examination. The PROGENSA PCA3 assay was used to determine PCA3 score in the urinary samples. A linear regression model was used to detect the associations between (single nucleotide polymorphisms) SNPs and PCA3 score under an additive genetic model, adjusting for age and population stratification. Two SNPs, rs10993994 in ß-microseminoprotein at 10q11.23 and rs10424878 in kallikrein-related peptidase 2 at 19q13.33, were associated with PCA3 score at genome-wide significance level (P = 1.22 x 10(-9) and 1.06 x 10(-8), respectively). Men carrying the rs10993994 "T" allele or rs10424878 "A" allele had higher PCA3 score compared with men carrying rs10993994 "C" allele or rs10424878 "G" allele (ß = 1.25 and 1.24, respectively). This is the first comprehensive search for genetic determinants of PCA3 score. The novel loci identified may provide insight into the molecular mechanisms of PCA3 expression as a potential marker of PCa.

The G84E mutation of HOXB13 is associated with increased risk for prostate cancer: results from the REDUCE trial.

A novel rare mutation, homeobox B13 (HOXB13) G84E, was reported to co-segregate with prostate cancer (PCa) in hereditary PCa families and associate with PCa risk in unrelated cases and controls. In this study, we aim to compare the G84E mutation frequency among subjects of different races/ethnicities from various geographic regions in the world and to assess its risk for developing PCa, in the Reduction by Dutasteride of Prostate Cancer Events (REDUCE) trial. All the 3508 subjects had initial negative prostate biopsy and were biopsied at Year 2 and 4 for detection of PCa. The G84E mutation was detected only in Caucasians, with the highest carrier frequency in Northern Europe (1.06%), followed by Western Europe (0.60%) and North America (0.31%). No mutation carrier was observed in Southern Europe, Eastern Europe, Latin America, Australia and South Africa. In Caucasians, the G84E mutation frequency was 0.99% and 0.24% in positive and negative biopsy subjects, respectively (P = 0.01). In positive biopsy subjects, the frequency was significantly higher in subjects with a positive family history than those without (4.31% versus 0.34%, P = 0.002). In the 4 year follow-up, the PCa detection rate was 53.8% among the 13 mutation carriers and 22.0% among 3186 non-carriers, relative risk = 2.45 (95% confidence interval: 1.48-4.07). All mutation carriers shared a common haplotype, suggesting a founder effect. In Finland, the G84E mutation was estimated to occur in the year 1792 (95% credible interval: 1735-1831). In conclusion, the G84E mutation of HOXB13, a relatively recent mutation that likely occurred in Northern Europe, significantly increases risk for PCa.

Genome-wide association study identifies loci at ATF7IP and KLK2 associated with percentage of circulating free PSA.

BACKGROUND: Percentage of free-to-total prostate-specific antigen (%fPSA) is an independent predictor of risk for prostate cancer among men with modestly elevated level of total PSA (tPSA) in blood. Physiological and pathological factors have been shown to influence the %fPSA value and diagnostic accuracy. MATERIALS/METHODS: To evaluate genetic determinants of %fPSA, we conducted a genome-wide association study of serum %fPSA by genotyping 642,584 single nucleotide polymorphisms (SNPs) in 3192 men of European ancestry, each with a tPSA level of 2.5 to 10 ng/ml, that were recruited in the REduction by DUtasteride of Prostate Cancer Events study. Single nucleotide polymorphisms (SNPs) with P < 10(-5) were further evaluated among the controls of a population-based case-control study in Sweden (2899 prostate cancer cases and 1722 male controls), including 464 controls having tPSA levels of 2.5 to 10 ng/ml. RESULTS: We identified two loci that were associated with %fPSA at a genome-wide significance level (P <5 x 10(-8)). The first associated SNP was rs3213764 (P = 6.45 x 10(-10)), a nonsynonymous variant (K530R) in the ATF7IP gene at 12p13. This variant was also nominally associated with tPSA (P = .015). The second locus was rs1354774 (P = 1.25 x 10(-12)), near KLK2 at 19q13, which was not associated with tPSA levels, and is separate from the rs17632542 locus at KLK3 that was previously associated with tPSA levels and prostate cancer risk. Neither rs3213764 nor rs1354774 was associated with prostate cancer risk or aggressiveness. CONCLUSIONS: These findings demonstrate that genetic variants at ATF7IP and KLK2 contribute to the variance of %fPSA.

Genome-wide association study identifies a new locus JMJD1C at 10q21 that may influence serum androgen levels in men.

Circulating androgen levels are often used as indicators of physiological or pathological conditions. More than half of the variance for circulating androgen levels is thought to be genetically influenced. A genome-wide association study (GWAS) has identified two loci, SHBG at 17p13 and FAM9B at Xp22, for serum testosterone (T) levels; however, these explain only a small fraction of inter-individual variability. To identify additional genetic determinants of androgen levels, a GWAS of baseline serum T and dihydrotestosterone (DHT) levels was conducted in 3225 men of European ancestry from the REduction by DUtasteride of Prostate Cancer Events (REDUCE) study. Cross-validation was used to confirm the observed associations between the drug (n = 1581) and placebo (n = 1644) groups of REDUCE. In addition to confirming the associations of two known loci with serum T levels (rs727428 in SHBG: P = 1.26 × 10(-12); rs5934505 in FAM9B: P = 1.61 × 10(-8)), we identified a new locus, JMJD1C at 10q21 that was associated with serum T levels at a genome-wide significance level (rs10822184: P = 1.12 × 10(-8)). We also observed that the SHBG locus was associated with serum DHT levels (rs727428: P = 1.47 × 10(-11)). Moreover, two additional variants in SHBG [rs72829446, in strong linkage equilibrium with the missense variant D356N (rs6259), and rs1799941] were also independently associated with circulating androgen levels in a statistical scale. These three loci (JMJD1C, SHBG and FAM9B) were estimated to account for ~5.3 and 4.1% of the variance of serum T and DHT levels. Our findings may provide new insights into the regulation of circulating androgens and potential targets for androgen-based therapy.

A comparison of Bayesian and frequentist approaches to incorporating external information for the prediction of prostate cancer risk.

We present the most comprehensive comparison to date of the predictive benefit of genetics in addition to currently used clinical variables, using genotype data for 33 single-nucleotide polymorphisms (SNPs) in 1,547 Caucasian men from the placebo arm of the REduction by DUtasteride of prostate Cancer Events (REDUCE®) trial. Moreover, we conducted a detailed comparison of three techniques for incorporating genetics into clinical risk prediction. The first method was a standard logistic regression model, which included separate terms for the clinical covariates and for each of the genetic markers. This approach ignores a substantial amount of external information concerning effect sizes for these Genome Wide Association Study (GWAS)-replicated SNPs. The second and third methods investigated two possible approaches to incorporating meta-analysed external SNP effect estimates - one via a weighted PCa 'risk' score based solely on the meta analysis estimates, and the other incorporating both the current and prior data via informative priors in a Bayesian logistic regression model. All methods demonstrated a slight improvement in predictive performance upon incorporation of genetics. The two methods that incorporated external information showed the greatest receiver-operating-characteristic AUCs increase from 0.61 to 0.64. The value of our methods comparison is likely to lie in observations of performance similarities, rather than difference, between three approaches of very different resource requirements. The two methods that included external information performed best, but only marginally despite substantial differences in complexity.

Potential impact of adding genetic markers to clinical parameters in predicting prostate biopsy outcomes in men following an initial negative biopsy: findings from the REDUCE trial.

BACKGROUND: Several germline single nucleotide polymorphisms (SNPs) have been consistently associated with prostate cancer (PCa) risk. OBJECTIVE: To determine whether there is an improvement in PCa risk prediction by adding these SNPs to existing predictors of PCa. DESIGN, SETTING, AND PARTICIPANTS: Subjects included men in the placebo arm of the randomized Reduction by Dutasteride of Prostate Cancer Events (REDUCE) trial in whom germline DNA was available. All men had an initial negative prostate biopsy and underwent study-mandated biopsies at 2 yr and 4 yr. Predictive performance of baseline clinical parameters and/or a genetic score based on 33 established PCa risk-associated SNPs was evaluated. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Area under the receiver operating characteristic curves (AUC) were used to compare different models with different predictors. Net reclassification improvement (NRI) and decision curve analysis (DCA) were used to assess changes in risk prediction by adding genetic markers. RESULTS AND LIMITATIONS: Among 1654 men, genetic score was a significant predictor of positive biopsy, even after adjusting for known clinical variables and family history (p = 3.41 × 10(-8)). The AUC for the genetic score exceeded that of any other PCa predictor at 0.59. Adding the genetic score to the best clinical model improved the AUC from 0.62 to 0.66 (p<0.001), reclassified PCa risk in 33% of men (NRI: 0.10; p=0.002), resulted in higher net benefit from DCA, and decreased the number of biopsies needed to detect the same number of PCa instances. The benefit of adding the genetic score was greatest among men at intermediate risk (25th percentile to 75th percentile). Similar results were found for high-grade (Gleason score ≥ 7) PCa. A major limitation of this study was its focus on white patients only. CONCLUSIONS: Adding genetic markers to current clinical parameters may improve PCa risk prediction. The improvement is modest but may be helpful for better determining the need for repeat prostate biopsy. The clinical impact of these results requires further study.

Extended treatment with lamivudine and adefovir dipivoxil in chronic hepatitis B patients with lamivudine resistance.

PURPOSE: We and others have reported that adding adefovir dipivoxil (adefovir) to lamivudine results in virological and biochemical improvement in cases of lamivudine resistance. The current study assessed the efficacy and safety of combined therapy after 104 weeks of combined treatment and analyzed the frequency of persistent lamivudine resistant HBV. METHODS: A total of 78 patients with compensated CHB (Group A) were maintained on either adefovir 10 mg daily (n = 38) or placebo (n = 40) while continuing lamivudine. An additional 38 patients with decompensated cirrhosis or post liver transplantation (Group B) received lamivudine plus adefovir. The primary endpoint was HBV DNA response at year 2. RESULTS: At week 104 of therapy, a significantly greater proportion of patients in Group A on combination therapy (76%) had a decline in serum HBV DNA to ≤10(5) copies or >2 log(10) reduction from baseline compared to those receiving lamivudine alone (13%; p < 0.001). Fifty-two percent of Group A patients on combination treatment continued to have the M204V/I HBV mutation compared to 92% receiving lamivudine alone (p = 0.0013). Virologic response occurred less frequently in patients expressing persistent lamivudine resistant HBV. In Group B, 87% of patients had HBV DNA response at week 104 (median change from baseline of -5.84 log(10) copies/mL). CONCLUSIONS: The combination of lamivudine and adefovir for 2 years generally proved effective in lamivudine-resistant cases, but there was a persistently high rate of detection of lamivudine resistant mutants and impaired virologic response in compensated patients.

Application of phosphoramidate ProTide technology significantly improves antiviral potency of carbocyclic adenosine derivatives.

We report the application of phosphoramidate pronucleotide (ProTide) technology to the antiviral agent carbocyclic L-d4A (L-Cd4A). The phenyl methyl alaninyl parent ProTide of L-Cd4A was prepared by Grignard-mediated phosphorochloridate reaction and resulted in a compound with significantly improved anti-HIV (2600-fold) and HBV activity. We describe modifications of the aryl, ester, and amino acid regions of the ProTide and how these changes affect antiviral activity and metabolic stability. Separate and distinct SARs were noted for HIV and HBV. Additionally, ProTides were prepared from the D-nucleoside D-Cd4A and the dideoxy analogues L-CddA and D-CddA. These compounds showed more modest potency improvements over the parent drug. In conclusion, the ProTide approach is highly successful when applied to L-Cd4A with potency improvements in vitro as high as 9000-fold against HIV. With a view to preclinical candidate selection we carried out metabolic stability studies using cynomolgus monkey liver and intestinal S9 fractions.

Application of phosphoramidate pronucleotide technology to abacavir leads to a significant enhancement of antiviral potency.

We report the first application of pronucleotide (ProTide) technology to the antiviral agent abacavir (Ziagen), used for the treatment of HIV infection. The phenylmethoxyalaninyl phosphoramidate of abacavir was prepared in good yield in one step. Also prepared was the corresponding phosphoramidate of the guanine nucleoside analogue "carbovir". The antiviral profile of each of the parent nucleosides was compared to that of the phosphoramidate ProTides. A significant (28- to 60-fold) increase in anti-HIV potency was noted for the ProTide of abacavir but not for that of carbovir. These findings were in agreement with the markedly higher (ca. 37-fold) levels of carbovir triphosphate that are formed in CEM cells upon response to the abacavir ProTide compared with the parent abacavir compound. In contrast the anti-HBV potency of both abacavir and carbovir were improved (10- and 20-fold, respectively) by ProTide formation. As in CEM cells, the abacavir ProTide provided significantly enhanced carbovir triphosphate levels in HepG2 2.2.15 cells over that of the parent nucleoside. On the basis of these data, a series of phosphoramidate analogues with structural variation in the ester and amino acid regions were prepared and their antiviral profiles described. In addition, the pharmacokinetic disposition of the abacavir phenylethoxyalaninyl phosphoramidate was evaluated in Cynomolgus monkeys.