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  4th Intl Lipodystrophy Workshop
San Diego at Coronado Beach, Sept 22-25, 2002
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HCV Viral Load Increases on HAART But CD4 Increase from HAART is Not Blunted: implications for when to begin HIV & HCV therapy
  Abstract title: Immune recovery is associated with persistent rise in hepatitis C virus RNA, infrequent liver test flares, and is not impaired by hepatitis C virus in co-infected subjects
Raymond T. Chung a; Scott R. Evans b; Yijun Yang b; Dickens Theodore c; Hernan Valdez d; Rebecca Clark e; Cecilia Shikuma f; Thomas Nevin g; Kenneth E. Sherman h; and the AIDS Clinical Trials Group 383 Study Team
AIDS 2002; 16(14):1915-1923
Abstract- Objectives:
The impact of highly active antiretroviral therapy (HAART) on hepatitis C virus (HCV) is unknown. We analysed changes in HCV RNA and the frequency of hepatotoxicity in co-infected patient enrolling in AIDS Clinical Trials Group trials, and determined whether HCV impairs successful immune reconstitution in these populations.
In a prospective analysis of co-infected patients completing at least 16 weeks of HAART in four trials, and co-infected patients with available stored plasma from two other completed HAART trials, HCV RNA was measured at baseline and to week 48. A retrospective analysis of immune recovery in 40 HCV-RNA-positive and 129 HCV-RNA-negative patients from a single trial was performed.
Prospective analysis: 60 patients completed at least 16 weeks of HAART. The mean HCV-RNA level increased 0.35 log10 IU/ml at week 16 and 0.43 log10 IU/ml at week 48. When stratified by baseline CD4 cell count, subjects' HCV-RNA levels increased 0.43 and 0.59 log10 IU/ml at weeks 16 and 48 for entry CD4 cell counts < 350 cells/mm3, but only 0.26 and 0.1 log10 IU/ml at weeks 16 and 48 for entry CD4 cell counts > 350 cells/mm3. Severe alanine aminotransferase elevations occurred in only 3.3%. Retrospective analysis: HCV co-infection had no effect on the overall mean CD4 cell increase at weeks 16 or 48 compared with uninfected controls.
In HCV-co-infected patients undergoing HAART, immune recovery is associated with a persistent increase in HCV RNA, especially with baseline CD4 cell counts < 350 cells/mm3. HCV co-infection did not antagonize the CD4 cell response to HAART.
Co-infection with hepatitis C virus (HCV) is remarkably frequent in individuals infected with HIV-1, in view of their shared routes of transmission [1]. Because of the importance of the immune system in controlling HCV infection, it is not surprising that levels of HCV RNA have been reported to be up to one log higher than in mono-infected individuals with HCV [2, 3]. The introduction of highly active antiretroviral therapy (HAART) has made the successful suppression of HIV-1-RNA replication possible in the great majority of treated patients. With successful immune restoration, it would be reasonable to predict that enhanced control of HCV would result, with the establishment of a new virus-host equilibrium or setpoint. It is also possible that with enhanced immune recognition of virus-infected hepatocytes an immunological flare directed against HCV could occur. So far, studies from Europe in HAART-treated co-infected patients have suggested that circulating HCV-RNA and aminotransferase levels increase transiently, but return to pre-HAART baseline levels.
We sought to examine the patterns of HCV viremia in patients undergoing HAART initiation in a US cohort entering into adult AIDS Clinical Trials Group (ACTG) treatment trials. In particular, the availability of subjects with a range of entry CD4 cell counts provided by the ACTG trials permitted the examination of the relationships between changes in HCV-RNA levels and baseline CD4 cell counts. In addition, we sought to determine how frequently alanine aminotransferase (ALT) flares occur in this population. Finally, because of recent reports suggesting that HCV blunts the immunological response to HAART [6], we conducted a retrospective cohort study to investigate whether HCV co-infection has adverse effects on the immunological effectiveness of HAART.
Increases in hepatitis C virus RNA with highly active antiretroviral therapy
Between the planned and unplanned prospective cohorts, 60 evaluable patients who completed at least 16 weeks of HAART were analysed. They were enrolled in several specific ACTG treatment trials of HAART: (i) the planned prospective cohort was predominantly composed of subjects co-enrolled in ACTG 384 and 388, two ongoing trials of antiretroviral therapy; and (ii) the unplanned cohort was derived from two completed trials, ACTG 320 [7] and ACTG 343 [8]. Baseline characteristics of the individual and composite cohorts are presented in Table 2a. The two cohorts did not differ with respect to sex, race, age, HCV genotype, or drug use. The planned cohort had significantly higher baseline HIV-1-RNA levels, lower CD4 cell counts and lower HCV-RNA levels than the unplanned cohort, a result of the broader inclusion criteria for the relevant clinical trials. For the entire cohort, the mean baseline log10 HIV-1-RNA copies/ml was 4.36, the CD4 cell count was 320 cells/mm3, and log10 HCV-RNA level was 6.19 IU/ml. Nearly all were HCV genotype 1 (85%).
The majority of evaluable subjects (53/60; 88%) in the overall cohort experienced reductions of HIV-1-RNA levels to less than 500 copies/ml by 16 weeks of HAART (data not shown). The mean increases in CD4 cell count by weeks 16 and 48 were +105 cells/mm3 (SD = 111) and +180 cells/mm3 (SD = 167), respectively (data not shown). Table 3 summarizes HCV-RNA increases at weeks 16 and 48. Overall, the mean increase in HCV-RNA level was 0.35 log10 at week 16 [95% confidence interval (CI) 0.13-0.57 log; P = 0.003] and 0.43 log10 at week 48 (95% CI 0.16-0.71 log; P = 0.001). HCV-RNA levels increased 0.43 and 0.59 log10 at weeks 16 and 48, respectively (P = 0.027, P < 0.001, respectively), for subjects with entry CD4 cell counts less than 350 cells/mm3, but only 0.26 and 0.10 log10 at weeks 16 and 48 for subjects with entry CD4 cell counts greater than 350 cells/mm3 (P = 0.04, P = NS, respectively). Overall, in patients starting from a more immunocompromised state (CD4 cell count < 350 cells/mm3), HCV-RNA levels increased early in HAART and remained persistently elevated at all timepoints until week 48, the last timepoint ascertained (Fig. 1a). In those subjects starting with CD4 cell counts greater than 350 cells/mm3, although significant increases in HCV-RNA levels were also recorded early in HAART, they tended to return back to baseline.
Alanine aminotransferase flares and discontinuation of highly active antiretroviral therapy
Because of reports of increases in ALT accompanying the initiation of HAART, often leading to treatment discontinuation in co-infected patients [4, 5, 9, 10], we examined the co-infected cohorts entering ACTG HAART trials for the frequency and magnitude of ALT elevations, especially those of grade 3 (over five times the upper limit of normal; ULN) or higher. We also assessed the treatment discontinuation rates in these groups. In those subjects whose ALT data were available throughout the study (prospective cohort, n = 29) baseline ALT was 49 (SD = 31). By 16 weeks of treatment, the mean ALT level rose to 73 (SD = 47; P = 0.001) and returned towards baseline by the end of the study (P = 0.01). This transient increase in ALT appeared to parallel the rise in CD4 cell counts and HCV-RNA levels, and the fall in HIV-1-RNA levels Of the 60 subjects, baseline ALT were grade 2 (2.5-5 ? ULN) in four subjects (6.7%) and grade 0 or 1 (< 1.25 ? ULN or 1.25-2.5 ? ULN) in the remainder. Severe (grade 3/4) ALT elevations (one grade 3 and one grade 4) occurred in only two men (3.3%) at weeks 24 and 28; one subject had normal ALT at entry and the other had normal or mild (grade 1) ALT at entry. Both of these subjects underwent temporary discontinuation of dosing but never required permanent HAART discontinuation. After re-initiation of drugs, both accomplished successful HIV-1-RNA suppression to less than 500 copies/ml. The four subjects who entered with grade 2 ALT remained at grade 2 or lower throughout the course of the study. The overall frequency of ALT elevations of grade 2 or higher was 12 out of 60 (20%). A descriptive analysis of sex suggests that women did not experience a disproportionately higher frequency of ALT elevations compared with men in this cohort, suggesting that hepatotoxicity was also infrequent in co-infected women. However, the overall number of women in this study was small (n = 8). Taken together, these data indicate that whereas ALT elevations are frequent, grade 3 or higher elevations were infrequent and the permanent discontinuation of HAART did not occur in an unselected subset of co-infected subjects entering these ACTG HAART trials.
Hepatitis C virus infection and immune recovery with highly active antiretroviral therapy
The cohort showed no significant differences between HCV-RNA-positive and HCV-RNA-negative subjects for baseline log10 HIV RNA (3.94 versus 3.71, HCV-positive versus HCV-negative) and CD4 cell count (482 versus 435 cells/mm3). Similarly, there were no significant differences with respect to sex and treatment arm, as the regimen for the first 6 months of this trial was uniform (indinavir-zidovudine-lamivudine). The HCV-positive group was somewhat older than the HCV-negative group. Because the treatments from months 7-24 were randomly divided to one of three arms (indinavir, zidovudine-lamivudine, zidovudine-lamivudine-indinavir maintenance for month 6 HIV-1-RNA responders), we confined our primary retrospective cohort analysis to week 16 outcomes. HCV co-infection had no effect on the overall mean CD4 cell increase at week 16 (+133 versus +100 cells/mm3, HCV-positive versus HCV-negative; P not significant); in those whose entry CD4 cell count exceeded 350 cells/mm3, the HCV-positive group experienced a higher mean CD4 cell increase. Similarly, there was a larger decrease in log10 HIV-1-RNA level (-2.55 versus -2.02 log10; P = 0.02) and a higher rate of HIV-1-RNA suppression to less than 500 copies/ml at week 16 in the HCV-positive group (97.4 versus 85.4%; P = 0.04). An analysis of available week 48 data revealed no significant differences between HCV- positive and -negative groups for the CD4 cell count increase, magnitude of HIV-1-RNA fall, or portion of subjects achieving HIV-1-RNA levels less than 500 copies/ml (data not shown). However, it should be noted that subjects were not receiving uniform antiretroviral therapy after week 24, and that samples were variably available for CD4 cell count and HIV-1-RNA level determinations at week 48.
In summary, in this retrospective cohort analysis of ACTG HAART trials using uniform study regimens, HCV co-infection did not appear to be associated with diminished HIV-1 or CD4 cell response to HAART, suggesting that HCV does not impair successful immune recovery. Indeed, early in treatment, it appeared to be associated with slightly improved antiretroviral therapy responses.
Discussion By Authors
It is well established that the immune containment of HCV is essential for the spontaneous clearance of acute infection as well as the control of chronic disease [11, 12]. In addition, circulating HCV-RNA levels rose by an order of magnitude or higher in states of immunosuppression, including solid organ transplantation [13], corticosteroid administration [14], and with HIV seroconversion [2, 3]. In this study, we sought to determine whether successful recovery of the immune system brought about by pharmacological suppression of HIV replication could reduce circulating HCV-RNA levels in co-infected hosts. Surprisingly, we found that the suppression of HIV-1 RNA and increases in CD4 cell counts were associated with significant increases in HCV-RNA levels at weeks 16 and 48, by nearly one-half log. This sustained increase in HCV-RNA levels appears to be confined to those subjects whose entry CD4 cell counts were less than 350 cells/ml. In contrast, those subjects starting HAART with CD4 cell counts greater than 350 cells/ml experienced transient increases in HCV-RNA levels at week 16, but levels returned to near baseline by week 48. Our data are similar to those reported by other European groups [4, 5] with respect to the increases in viral levels at week 16, but differ from those studies in that these increases were sustained. Therefore, instead of a more favorable equilibrium level associated with immune recovery, HCV replication appears to be enhanced. This finding, especially in more immune compromised hosts, could be explained in several ways. First, enhanced HCV-RNA levels may reflect the replication of a diverse repertoire of quasispecies whose diversity was enhanced during a period of immune compromise [15]. Under this theory, only the most dominant or fittest of the quasispecies replicates during immunodeficiency. With successful enhancement of the immune response, the newly applied selection pressure would contain the dominant quasispecies, but instead could drive the replication of the minority quasispecies, leading to potential net increases in HCV-RNA levels. An alternative explanation could lie in the fact that HCV appears to replicate within peripheral blood mononuclear cells [16]. Under basal conditions of co-infection, HIV and HCV would exist in a competitive relationship for this reservoir. With successful clearance of HIV-infected lymphocytes, HCV-RNA levels would increase as more susceptible target cells become available. Our finding of increased HCV-RNA with CD4 cell levels supports this model. These models, which are testable, could also explain why the findings are more prominent in more immunocompromised hosts.
Irrespective of their basis, these findings suggest that those co-infected individuals undergoing treatment for HIV experience increased HCV replication with successful immune recovery. This may have implications for the treatability of HCV, as increased HCV-RNA levels have been associated with diminished responses to antiviral therapy in individuals singly infected with HCV [17, 18]. This is particularly relevant as antiretroviral therapy recommendations for HIV have narrowed to those individuals whose CD4 cell count falls below 350 cells/ml, the group for whom this observation was most pronounced (www.hiv.atis.org).
Early in HAART, we observed parallel increases in ALT levels, CD4 cell counts, and reductions in HIV-1-RNA levels in co-infected patients. With continued treatment, the ALT level tended to return toward baseline. These observations suggest that CD4 cell reconstitution may be associated with an HCV immunological flare, and support the findings of others [4, 5]. Overall, we observed a very low rate of clinically significant antiretroviral-associated hepatotoxicity in our treatment cohorts, defined as grade 3 or higher ALT. In fact, no subject required permanent HAART discontinuation. These findings differ from those of some other, larger observational cohorts, and may do so for several reasons [9, 10]. First, this was a clinical trial cohort, for whom baseline ALT levels were normal or only mildly elevated, and may therefore have been biased towards the selection of subjects with milder liver disease. Second, there were significant restrictions on substance use for inclusion in these trials, which may have further reduced the risk of toxicity in these subjects. Nonetheless, the fact that nearly all co-infected subjects in this smaller cohort successfully underwent HAART without hepatotoxicity supports the belief that the safe initiation of HAART can occur in co-infected individuals with apparently mild clinical HCV disease. Indeed, some observational cohorts have found no increased risk conferred by HCV co-infection [19]. Further prospective studies on co-infected cohorts should be performed to clarify the extent of the risk of hepatotoxicity posed by HCV.
It has been convincingly demonstrated that HIV adversely affects the natural history of HCV-related liver disease [20-22]. However, more recently, it has been suggested that HCV may have adverse effects on the progression of HIV-related disease [6, 23, 24], and that HCV co-infection diminishes the effectiveness of HAART [6]. Our retrospective comparison of sera from a uniform ACTG naive HAART trial suggested that there were no differences in HIV suppression and the magnitude of CD4 cell increase between HCV-seropositive, RNA-positive subjects and HCV-seronegative, RNA-negative subjects. Whereas these were not designed to be matched controls, HCV-positive were compared with HCV-negative subjects from a representative sample identified in ACTG 343 [1]. They had similar baseline characteristics and were on identical treatment regimens for the first 24 weeks. Our groups were thus more likely to be better matched than those from larger cohort studies, whose antiretroviral regimens were variable, and in whom ongoing injection drug use took place in a large proportion [6]. Our finding of no diminution (and at early timepoints, an improvement) of HAART efficacy may reflect several factors. Although histological data are not available, it is quite likely that our cohort of co-infected subjects, because they were included in clinical trials, reflected a milder subset of HCV disease, and thus did not experience impaired HAART response. It is also possible that the observations of blunted immune recovery seen in HCV-HIV-positive individuals in the large cohort of Greub et al. [6] may reflect independent effects attributable to ongoing drug use. These were not significant factors in ACTG 343. Because our analysis was confined to 16 and 48 weeks after the initiation of HAART, it is possible that meaningful differences in immune recovery may be revealed only with longer-term follow-up, as seen in the study by Greub et al. [6]. Finally, the failure to find a significant effect of HCV co-infection may be partly due to a lack of power. Assuming that the true variability of the changes is similar to the variability of the changes observed, there was 82% power to detect a difference of 75 cells between CD4 cell changes in the HCV-RNA-positive and the HCV-RNA-negative groups. Our power to detect smaller differences was therefore smaller. Nonetheless, in a clinical trial population over the short term, we did not find evidence to suggest that HCV co-infection is associated with less effective antiretroviral treatment response.
It will still be essential to ascertain HCV infection status in the HIV-positive individual about to undergo antiretroviral therapy, so that appropriate decisions about the stage of liver disease and, if warranted, earlier treatment of HCV, can be made. Nonetheless, our data suggest that in a US clinical trials cohort, HCV does not impair short-term immune recovery or cause significant ALT flares, but that its own equilibrium may be adversely affected by HAART. The impact of this equilibrium change on the natural history of HCV awaits further study.
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