Regis A. Vilchez

Randomized phase 3 trial of ombitasvir/paritaprevir/ritonavir for hepatitis C virus genotype 1b–infected Japanese patients with or without cirrhosis

GIFT‐I is a phase 3 trial evaluating the efficacy and safety of a 12‐week regimen of coformulated ombitasvir (OBV)/paritaprevir (PTV)/ritonavir (r) for treatment of Japanese hepatitis C virus genotype 1b–infected patients. It consists of a double‐blind, placebo‐controlled substudy of patients without cirrhosis and an open‐label substudy of patients with compensated cirrhosis. Patients without cirrhosis were randomized 2:1 to once‐daily OBV/PTV/r (25 mg/150 mg/100 mg; group A) or placebo (group B). Patients with cirrhosis received open‐label OBV/PTV/r (group C). The primary efficacy endpoint was the rate of sustained virological response 12 weeks posttreatment in interferon‐eligible, treatment‐naive patients without cirrhosis and hepatitis C virus RNA ≥100,000 IU/mL in group A. A total of 321 patients without cirrhosis were randomized and dosed with double‐blind study drug (106 received double‐blind placebo and later received open‐label OBV/PTV/r), and 42 patients with cirrhosis were enrolled and dosed with open‐label OBV/PTV/r. In the primary efficacy population, the rate of sustained virological response 12 weeks posttreatment was 94.6% (106/112, 95% confidence interval 90.5‐98.8). Sustained virological response 12 weeks posttreatment rates were 94.9% (204/215) in group A, 98.1% (104/106) in group B (open‐label), and 90.5% (38/42) in group C. Overall, virological failure occurred in 3.0% (11/363) of patients who received OBV/PTV/r. The rate of discontinuation due to adverse events was 0%‐2.4% in the three patient groups receiving OBV/PTV/r. The most frequent adverse event in patients in any group was nasopharyngitis. Conclusion: In this broad hepatitis C virus genotype 1b–infected Japanese patient population with or without cirrhosis, treatment with OBV/PTV/r for 12 weeks was highly effective and demonstrated a favorable safety profile. (Hepatology 2015;62:1037‐1046)

An International Multicenter Performance Analysis of Cytomegalovirus Load Tests

A new quantitative polymerase chain reaction assay, COBAS AmpliPrep/COBAS TaqMan CMV Test, was developed using the first World Health Organization cytomegalovirus standard. It demonstrated a high level of interlaboratory agreement and precision compared to quantitative results obtained with tests used by 5 different laboratories.

Randomized trial of interferon‐ and ribavirin‐free ombitasvir/paritaprevir/ritonavir in treatment‐experienced hepatitis C virus–infected patients

Approximately 2 million Japanese individuals are infected with hepatitis C virus and are at risk for cirrhosis, end‐stage liver disease, and hepatocellular carcinoma. Patients in whom interferon (IFN)/ribavirin (RBV) therapy has failed remain at risk as effective therapeutic options are limited. This phase 2, randomized, open‐label study evaluated an IFN‐ and RBV‐free regimen of once‐daily ombitasvir (ABT‐267), an NS5A inhibitor, plus paritaprevir (ABT‐450), an NS3/4A protease inhibitor dosed with ritonavir (paritaprevir/ritonavir), in pegylated IFN/RBV treatment–experienced Japanese patients with hepatitis C virus subtype 1b or genotype 2 infection. Patients without cirrhosis (aged 18‐75 years) with subtype 1b infection received ombitasvir 25 mg plus paritaprevir/ritonavir 100/100 mg or 150/100 mg for 12 or 24 weeks; patients with genotype 2 infection received ombitasvir 25 mg plus paritaprevir/ritonavir 100/100 mg or 150/100 mg for 12 weeks. Sustained virologic response (SVR) at posttreatment week 24 (SVR24) was the primary endpoint. Adverse events were collected throughout the study. One hundred ten patients received ≥1 dose of study medication. In the subtype 1b cohort, SVR24 rates were high (88.9%‐100%) regardless of paritaprevir dose or treatment duration. In the genotype 2 cohort, SVR24 rates were 57.9% and 72.2% with 100 mg and 150 mg of paritaprevir, respectively. The SVR24 rate was higher in patients with subtype 2a (90%) than 2b (27%). Concordance between SVR12 and SVR24 was 100%. The most common adverse events overall were nasopharyngitis (29%) and headache (14%). Conclusion: In this difficult‐to‐treat population of patients in whom prior pegylated IFN/RBV had failed, ombitasvir/paritaprevir/ritonavir demonstrated potent antiviral activity with a favorable safety profile among Japanese patients with hepatitis C virus genotype 1b or 2a infection. (Hepatology 2015;61:1523–1532)

An International Multicenter Performance Analysis of CMV Viral Load Tests

A new quantitative polymerase chain reaction assay, COBAS AmpliPrep/COBAS TaqMan CMV Test, was developed using the first World Health Organization cytomegalovirus standard. It demonstrated a high level of interlaboratory agreement and precision compared to quantitative results obtained with tests used by 5 different laboratories.

Evolution in the sensitivity of quantitative HIV-1 viral load tests

Significant advancements in molecular diagnostics have been made since the inception and application of PCR-based technologies in clinical diagnostic laboratories and the management of HIV-1 infected patients. More recently, real-time PCR has improved the overall performance of assays used for detecting and quantifying HIV-1 RNA viral load in patients undergoing antiretroviral treatment. The effects of these changes and the interpretations of the HIV-1 viral load results are discussed in this review in the context of the different assays used, the viral dynamics of the HIV-1 virus, and the recent changes to HIV-1 treatment guidelines.

HCV RNA Viral Load Assessments in the Era of Direct-Acting Antivirals

Recent regulatory approvals of the NS3/4A protease inhibitors boceprevir and telaprevir launched a new therapeutic era for hepatitis C virus (HCV) genotype 1 infection. Decisions to shorten, extend, or stop treatment with these direct-acting antiviral (DAA) regimens require accurate quantification of serum HCV RNA levels. To effectively use DAA therapies, clinicians must understand performance characteristics of HCV RNA real-time PCR assays and the clinical significance of HCV RNA that is detectable below the lower limit of quantification. This review summarizes terms used to report HCV RNA viral load results, explains the analytical performance of the PCR assay used in the clinical trials of boceprevir and telaprevir, and compares currently available commercial assays.

CMV antigenemia and quantitative viral load assessments in hematopoietic stem cell transplant recipients

BACKGROUND Sensitive and reliable diagnostic tests are essential for the prevention of cytomegalovirus (CMV) disease after hematopoietic stem cell transplantation (HSCT). pp65 antigenemia and polymerase chain reaction (PCR) assays are commonly used to monitor CMV in HSCT recipients. However, there is considerable intra- and inter-laboratory variability in the results, which impact comparability and clinical practice. OBJECTIVES/STUDY DESIGN Using 380 samples from 135 HSCT recipients, we compared the new FDA approved quantitative PCR assay, COBAS(®) AmpliPrep/COBAS(®) TaqMan(®) CMV test (CAP/CTM CMV test) developed and standardized using the 1st WHO International Standard for CMV with pp65 antigenemia and COBAS(®) AMPLICOR MONITOR CMV tests. RESULTS The median time between transplantation and testing samples was 57 days (range, 0-207 days). The median CMV load (log(10)) was 3.17 IU/mL (3.21 copies/mL). Among samples with detectable CMV load, 52% were negative by pp65 antigenemia. CMV loads were higher in pp65 antigenemia-positive than in negative samples. One pp65-antigenemia-positive cell per 100,000 leukocytes corresponded to a median CMV load of 1200 IU/mL. CMV loads determined by the CAP/CTM CMV test were slightly lower than the ones by the AMPLICOR MONITOR CMV test (-0.15 [95% CI, -0.18 to -0.13] copies/mL), but slope differences indicated only limited co-linearity. CONCLUSIONS The CAP/CTM CMV test is more sensitive than pp65 antigenemia and the AMPLICOR MONITOR CMV test in HSCT recipients. The lower limit of quantification and co-linearity with the international WHO standard renders the CAP/CTM CMV test suitable for future clinical trials defining viral load thresholds of CMV therapy.

Comparison of two quantitative real-time CMV-PCR tests calibrated against the 1st WHO international standard for viral load monitoring of renal transplant patients

Cytomegalovirus (CMV) replication in organ transplant recipients is commonly diagnosed by quantitative PCR methods. However, there has been a poor inter‐laboratory correlation of viral load values due to the lack of an international reference standard. In a recent study, the COBAS® AmpliPrep/COBAS® TaqMan® (CAP/CTM) CMV test calibrated to the 1st WHO CMV standard, showed good reproducibility in CMV load values across multiple laboratories. Fifty‐seven follow‐up plasma specimens from 10 kidney transplant recipients with CMV replication were examined using the new quantitative CAP/CTM CMV test and the “in‐house” quantitative CMV real‐time PCR method, also calibrated against the 1st WHO CMV standard for their clinical applicability for monitoring CMV load in renal transplant patients. By CAP/CTM CMV test 49/57 specimens were CMV‐DNA positive compared to 44/57 by the “in‐house” PCR test. The “in‐house” PCR and CAP/CTM CMV test correlated well in monitoring individual kidney transplant patients. Conversion of the CMV‐DNA copies to IUs made the results of the “in‐house” PCR and CAP/CTM CMV test less uniform in analysis of the patient samples. In specimens of one patient, significant underquantification of CMV load with “in‐house” PCR emerged during follow‐up due to a point mutation in the “in‐house” PCR primer sequence. The CAP/CTM CMV test was found suitable for diagnosing and monitoring CMV replication in renal transplant patients. Multicenter studies are needed to provide more information of the commutability of the 1st WHO CMV standard and to define the clinical thresholds. J. Med. Virol. 86:576–584, 2014.

An update on treatment of hepatitis C virus genotype 1 infection and viral load assessments

According to the recently released American Association for the Study of Liver Diseases (AASLD) guidelines for the treatment of hepatitis C virus (HCV) genotype 1 chronic infection, in treatment-naı̈ve subjects the association of boceprevir or telaprevir with peginterferon-alpha and ribavirin is strongly recommended as the optimal therapy. In patients treated with boceprevir, peginterferon, and ribavirin, a response-guided treatment schedule was established at week 8, through the assessment of HCV RNA level, making feasible a shortened duration of treatment (i.e., 28 weeks) in the case of undetectable viral replication. In this regard, we believe that the choice of 8 weeks for the definition of treatment duration needs some comment. The phase 2 and 3 clinical trials with boceprevir featured the use of peginterferon-ribavirin for 4 weeks (the lead-in period) before boceprevir was added. The reasons for starting with a lead-in phase would be to lower HCV-RNA before exposure to a protease inhibitor in order to reduce the risk of resistance and viral breakthrough. However, in the studies mentioned the achievement of virologic response after the lead-in therapy (4 weeks) was shown to be highly effective for the prediction of sustained virologic response (SVR; HCV-RNA undetectability leading to SVR in a percentage of patients between 89% and 100%, independently from the treatment arm). Indeed, Poordad et al. stated that in patients with undetectable HCV RNA levels after the lead-in period, boceprevir administration would not result in a higher rate of SVR than that obtained with the use of standard therapy. Therefore, the lead-in period as well as interleukin (IL)-28B genotype assessment might be used to better define the eligible patients for peginterferon introduction, thus avoiding their possible overuse with additional costs and side effects. In our opinion, it seems to be reasonable to reconsider the assessment of HCV-RNA at week 4 (end of lead-in) in the response-guided treatment guidelines of naı̈ve genotype-1-infected patients.