Detection of residual hepatitis C virus RNA by transcription-mediated amplification in patients with complete virologic response according to polymerase chain reaction-based assays

Transcription-mediated amplification is more sensitive than conventional PCR-based assays for detecting residual serum HCV RNA at end of treatment

OBJECTIVE

In patients chronically infected with hepatitis C virus (HCV) undergoing antiviral therapy, sustained virologic response is suggested by viral clearance by end of treatment (EOT). Viral clearance is defined by nondetection of serum HCV RNA, usually by qualitative PCR-based assays with limits of detection ranging from 100 to 1000 copies/ml. However, some individuals relapse after achieving apparent viral clearance by EOT. These individuals may have low levels of viremia not detected by current PCR methods. The aim of this retrospective study was to determine whether the Bayer HCV RNA Qualitative Assay, which employs Transcription Mediated Amplification (TMA) and detects 50 HCV RNA copies/ml, could detect residual serum HCV RNA in patients who achieved apparent viral clearance by EOT and subsequently relapsed.

METHODS

Samples were obtained at EOT (wk 24 or 48) and follow-up (wk 24-26 posttreatment) from 97 patients treated for HCV (78 relapsing patients, 19 sustained responders). All samples in which HCV RNA was not detected by PCR were tested in a blinded manner for HCV RNA by the TMA-based assay.

RESULTS

HCV RNA was detected by the TMA-based assay in 27 (34.6%) EOT and 76 (97.4%) follow-up samples from relapsing patients, but not in any of the EOT or follow-up samples from sustained responders.

CONCLUSION

Residual serum HCV RNA was detected by the TMA-based assay in EOT samples from 34.6% of patients that had achieved apparent viral clearance by PCR. The detection of HCV RNA by the TMA-based assay could help redefine EOT response and assist in the antiviral management of HCV infection.

Effect of HCV viral dynamics on treatment design: lessons learned from HIV

Viral load measurements provide an indication of viral replication, and thereby serve as a valuable tool to guide the initiation of therapy and subsequent changes. Plasma human immunodeficiency viral load strongly predicts the rate of decrease in CD4+ lymphocyte count, and progression to AIDS and death. Furthermore, the efficacy of antiretroviral therapy can be assessed by monitoring changes in plasma human immunodeficiency viral load. Similarly, viral load provides valuable information about the natural history of the hepatitis C virus infection. Hepatitis C viral load can be used to predict the likelihood of response to standard interferon-alpha treatment and other interferon-alpha regimens and to monitor treatment efficacy. Increased understanding of the natural history of the hepatitis C virus infection and the nature of resistance to interferon-alpha therapy suggests that effective treatment regimens must maintain serum levels of interferon-alpha. Ideally, interferon-alpha serum levels should provide constant pressure on the virus and should prevent viral rebound, thereby avoiding continued viral replication and minimizing the potential for emergence of resistant quasi-species. Current regimens designed to address these points include early aggressive intervention, combination drug regimens, prolonged maintenance, and novel interferons. By enabling the design and rapid assessment of new treatment regimens, viral load measurement will revolutionize the clinical management of the hepatitis C virus infection, as it has the HIV.

Advances in the molecular diagnosis of hepatitis C and their clinical implications

Serologic assays for diagnosis of hepatitis C infection may yield indeterminate results despite improvements in sensitivity and specificity through second- and third-generation assays. Direct detection of hepatitis C virus (HCV) RNA based on qualitative reverse transcription-polymerase chain reaction or transcription-mediated amplification allows diagnosis in the early stages of acute infection and in patients unable to mount an antibody response. Quantitative HCV RNA assays are useful for selecting appropriate antiviral therapies, but until recently they have lacked comparability between tests. More sensitive qualitative assays should be used for determining duration of treatment or recognizing a sustained virologic response to therapy. Hepatitis C virus genotyping can be performed from a limited sequence analysis of the viral genome by using various techniques. Although newer genotyping methods are relatively practicable and are satisfactory for the discrimination of the majority of genotypes, discrimination between subtypes can be challenging. Serologic typing of HCV lacks sensitivity and specificity compared with molecular-based techniques. Recent advances in serologic assays and nucleic acid detection techniques allow physicians to make accurate diagnoses, and these assays serve as important tools in treatment planning.

Assessment, by transcription-mediated amplification, of virologic response in patients with chronic hepatitis C virus treated with peginterferon alpha-2a

Transcription-mediated amplification (TMA) is an isothermal, autocatalytic target amplification method which has the potential to detect less than 50 hepatitis C virus (HCV) RNA copies/ml (10 IU/ml). The TMA assay was used to assess the presence of residual HCV RNA in plasma from patients treated with polyethylene glycol-modified interferon alpha-2a (peginterferon alpha-2a) who showed a virologic relapse after the end of therapy. Stored end-of-treatment and end-of-follow-up plasma samples from 177 of 267 patients treated with peginterferon alpha-2a (S. Zeuzem et al., N. Engl. J. Med. 343:1666--1672, 2000) were available for retesting by TMA. Plasma samples from patients in the same study who exhibited virologic relapse after treatment with standard interferon alpha-2a served as controls. Virologic response during the trial was defined as HCV RNA that was undetectable using a PCR-based test system with a sensitivity of 50 IU/mL (Cobas Amplicor HCV version 2.0) and was compared with TMA-based retesting results (VERSANT HCV RNA Qualitative Assay). Residual HCV RNA was detected in 4 of 60 cases (7%) by the TMA technology in end-of-treatment plasma samples from patients who relapsed after receiving peginterferon alpha-2a and in 6 of 18 patients (33%) following therapy with standard interferon alpha-2a. For peginterferon alpha-2a-treated patients with sustained virologic response, HCV RNA was detectable by TMA in end-of-treatment samples in 3 of 78 cases but in none of the end-of-follow-up samples. For all end-of-treatment and end-of-follow-up plasma samples of virologic nonresponders, a complete concordance between the PCR-based assay and TMA was observed. In conclusion, in patients with virologic relapse after the end of therapy, according to PCR, who were treated with peginterferon alpha-2a or standard interferon alpha-2a, residual HCV RNA was detectable in end-of-treatment samples by the TMA-based assay in 7 or 33% of cases, respectively. The lower rate of residual HCV RNA detection by TMA for patients treated with peginterferon alpha-2a than that for patients treated with standard interferon alpha-2a may be due to the maintained antiviral pressure of the long-acting peginterferon alpha-2a at the end-of-treatment visit.

Treatment of patients with chronic hepatitis C not responding to interferon with high-dose interferon alpha with or without ribavirin: final results of a prospective randomized trial. Austrian Hepatitis Study Group

OBJECTIVE

To investigate the efficacy of high-dose interferon alpha (IFN-alpha) with or without ribavirin in interferon (IFN) non-responders.

STUDY DESIGN

304 chronic hepatitis C patients received 5 MU IFN-alpha2b (IntronA, Schering-Plough, Kenilworth, NJ, USA) three times a week for 3 months. Non-responders were randomized either to continue with IFN (IFN 5 MU/TIW followed by 10 MU/TIW, each for 3 months) alone (group A: n = 76, m: f = 54: 22, age 45.7 +/- 12 years, 16% cirrhosis, alanine aminotransferase [ALT] 66 +/- 35 U/l) or in combination with ribavirin (approximately 14 mg/kg/day) (group B: n = 81, m: f = 57: 24, age 48.2 +/- 12 years, 17% cirrhosis, ALT 71 +/- 40 U/l). At the end of treatment, patients were followed for 6 months.

MAIN OUTCOME MEASURES

Virological response at end of treatment and 6 months thereafter.

SETTING

University hospitals and tertiary referral centres.

RESULTS

At the end of treatment, eight (10.8%) and 25 (31.3%, P= 0.0066) patients were HCV-RNA negative, and 51 and 39 were HCV-RNA positive, in groups A and B, respectively. There were 17 drop-outs in each group. Six months after treatment, only one patient in group A (1.3%) and seven patients (8.6%, P= 0.06) in group B had normal ALT and undetectable serum HCV-RNA.

CONCLUSIONS

A combination of high-dose IFN with ribavirin induces a short-lasting complete response in about one-third of IFN-non-responders.