Friday, February 8, 2013

Vitamins? The Magic Bullet Against Hepatitis C

Vitamins? The Magic Bullet Against Hepatitis C
Hans L Tillmann
Expert Rev Anti Infect Ther. 2012;10(11):1273-1277.

Evaluation of: Rocco A, Compare D, Coccoli P et al. Vitamin B12 supplementation improves rates of sustained viral response in patients chronically infected with hepatitis C virus.

Gut doi:10.1136/gutjnl-2012-302344 (Epub ahead of print) (2012).

Vitamin B12 was first mentioned to have a role in HCV treatment approximately a decade ago, but it has not been well translated into clinical medicine. Recently, however, a randomized trial has reported significantly better response at all time-points during therapy with pegylated interferon plus ribavirin, if such therapy was combined with vitamin B12. This correlates with reports on vitamin B12 being able to inhibit HCV in vitro and a report that vitamin B12 levels were related to treatment response. If further validated, vitamin B12 is another vitamin reported to be beneficial for HCV therapy. Vitamin D had repeatedly been reported to be associated with response to HCV therapy. It will be interesting to see whether vitamins such as B12 and D will remain relevant in the light of direct antivirals.

Vitamin B12 was reported to inhibit HCV via internal ribosome entry-site inhibition in the early 2000s,[1–3] but the findings were never confirmed nor rejected by anyone other than the group who published the initial reports. The first and so far only published clinical evaluation of vitamin B12 levels in patients concerning clinically relevant outcome was reported by Swedish investigators in 2011,[4] who described that patients achieving an end of treatment response (ETR) had significantly higher baseline vitamin B12 levels (331 pM in ETR vs 260 pM in nonresponders; p = 0.012) and that ETR was achieved in 25 out of 26 patients (96.2%; 95% CI: 81–99%) with vitamin B12 levels >360, versus 50 out of 73 patients (68.5%; 95% CI: 57–78%) with lower levels. For sustained viral response (SVR), the difference, however, was no longer significantly different (17 out of 26 [65%] vs 38 out of 73 [52%]; p = 0.26).

Prior to that publication on baseline vitamin B12 levels to predict antiviral response, a group in Italy initiated a placebo-controlled study in 2006, to evaluate whether supplemental vitamin B dosing would increase response over 'standard of care' (SOC) for HCV, which consisted of pegylated interferon (Peg-IFN) and ribavirin at that time. The study's report will be reviewed here.

Ninety four patients were randomly assigned to Peg-IFN and ribavirin or Peg-IFN and ribavirin plus vitamin B12 5 mg (Dobetin®, Angelini, Rome, Italy) intramuscular (im.) every 4 weeks for the duration of antiviral therapy. Two different Peg-IFNs were used interchangeably, although they are not interchangeable in practice. Interferon was dosed at 180 µg/week for Peg-IFN-α2a and 1.5 µg/kg/week for Peg-IFN-α2b, which is the standard dosing. Ribavirin was used at 800–1200 mg daily.

HCV genotypes were determined and viral loads were assessed by standard assays. Stratification was only performed for HCV genotypes 1 and 4 (although there was actually no genotype 4 patient included) versus 2 and 3, with only a few genotype 3 patients included. HCV RNA was determined using the reverse transcriptase (RT)-PCR, Roche COBAS® AMPLICOR® 2.0 assay (Roche Diagnostics, Basel, Switzerland), which has been reported to have a limit of detection of about 50 IU/ml.[5]

The study included 94 patients; 130 were screened but 36 were excluded owing to previous treatment (n = 21), HBV coinfection (n = 3), heavy alcohol consumption (n = 3), declined antiviral therapy (n = 3), severe depression (n = 2), poorly controlled diabetes (n = 2), plan for pregnancy (n = 1) and known hepatocellular carcinoma (n = 1).

There were two genotype 1a patients, 62 genotype 1b patients, 26 genotype 2 and four genotype 3 patients, with each group of genotypes evenly distributed between the two arms: one, 31, 13 and two patients, respectively. In addition, other patient characteristics were not significantly different between treatment arms such as fibrosis stage, grade of steatosis, age, gender and BMI, as well as IL28B polymorphisms for those where such information was available.

Overall rapid viral response (RVR) defined as HCV RNA <50 IU/ml at week 4 was achieved in 49% of SOC and 68% of those treated with vitamin B12 supplementation 5 g im. 4-weekly. Divided by genotype 1 versus 2/3 shows 34% (11 out of 32 SOC) versus 53% (17 out of 32 SOC plus vitamin B12) and for genotype 2/3: 80% (12 out of 15 SOC) versus 100% (15 out of 15 SOC plus vitamin B12), respectively. At this point, none of the differences were significant.

For week 12, complete viral response, defined as HCV RNA undetectable by HCV RT-PCR (Cobas Amlicor, limit of detection ~50 IU/ml), and the overall differences were significant (64% [30 out of 47] vs 85% [40 out of 47; p = 0.03], and 56% [18 out of 32 SOC] vs 78% [17 out of 32 SOC plus vitamin B12] and 80% [12 out of 15 SOC] vs 100% [15 out of 15 SOC plus vitamin B12], respectively), if divided by genotype 1 versus 2/3. The results split according to genotype were not significantly different, partially owing to small numbers in each subgroup.
At the end of treatment, the viral response rates were: 63% for genotype 1 (29 out of 47) versus 83% for genotype 2/3 (39 out of 47; p = 0.03) overall, and 53% (17 out of 32 SOC) versus 75% (24 out of 32 SOC plus vitamin B12) in genotype 1 patients and 80% (12 out of 15 SOC) versus 100% (15 out of 15 SOC plus vitamin B12) in genotype 2/3 patients, respectively. The most important outcome of SVR was also significantly different, overall (18 out of 47 [38%] vs 34 out of 47 [72%]), and when limited to genotype 1 patients: 22 versus 63% SVR (p = 0.003). However, the very good SVR rate of 11 out of 15 (73%) in genotype 2 out of 3 patients on SOC was higher, but not significantly different, in the patients receiving SOC plus vitamin B12 with 14 out of 15 (93%). No additional side effects were reported on respective therapies; it seems that vitamin B12 dosing at 5 mg im. every 4 weeks does not lead to additional side effects but does appear to increase response.

A decade after the first description of vitamin B12 being able to inhibit HCV replication in vitro, this study is the first one to randomize patients to SOC plus vitamin B12 versus SOC alone. The study reports dramatic improvement in response in the more difficult-to-treat genotype 1 patients with 63% SVR versus 22% SVR (p = 0.003), while the difference was less impressive in the easier-to-treat genotype 2/3 patients, where still a 20% difference was reported, and if confirmed in larger trials, this would be clinically significant.

The study had a few technical shortcomings, as important information concerning treatment response was not well established when the study was started, which limits the certainty of the study findings. Unfortunately, there is a substantial difference in response to Peg-IFN-α2a and Peg-IFN-α2b when used for HCV infection, where Peg-IFN-α2a is superior to Peg-IFN-α2b.[6] Thus, it would have been preferential to have only one of the interferons.
In addition, IL28B genotyping was not available for stratification as that was not a known factor for viral response at the time of the study; however, response rates were shown to vary between 38 and 80% depending on IL28B genotype.[7] Uneven distribution despite randomization cannot be excluded.

[8] However, the authors did the best they could and assessed IL28B genotype in a large proportion of the patients in the study. The data presented with such information available were similar to the overall trend. Data were presented for 42 genotype 1 patients, where IL28B was available, and the results were concordant with the assumption that vitamin B12 would be beneficial across different IL28B genotypes.

The study had another surprising result that might limit their generalizability – that is, the RVR and SVR rates reported for the SOC arm. The RVR rate of 34% (95% CI: 20–52%) is much higher for genotype 1 patients. For most studies, approximately 10% of genotype 1 patients were reported to achieve RVR;[9,10] on the other hand, the SVR rate of 22% (95% CI: 11–39%) in the SOC arm is lower than what is to be expected for patients treated with Peg-IFN plus ribavirin.[9,10] What makes the study findings even more surprising is that RVR and SVR rates were not only unusual, but despite better than expected RVR rates in the SOC arm, the SVR rates at the end of therapy were lower than expected. However, if confirmed the findings are huge.

Expert Commentary
The current aim of most therapies in HCV infection is the eradication of the viral infection, which is considered achieved when HCV RNA remains undetectable for 24 weeks after the end of the therapy: so-called SVR. When the study, cited above, was performed, only approximately 40% of North American patients with HCV genotype 1 infection achieved sustained response when treated with Peg-IFN (180 µg IFN-α2a weekly or 1.5 µg/kg IFN-α2b weekly) and ribavirin (800–1400 mg daily) for 48 weeks.[11] European patients usually respond slightly but not significantly better.

In that regard, the reported mere 22% (seven out of 32 patients; 95% CI: 11–39%) SVR rate in the SOC arm is surprising. This is significantly lower than the expected response rates from Italy. Nevertheless, the response looks promising at 63% (20 out of 32 patients; 95% CI: 46.3–79.7%) in the vitamin B12 treatment arm, where vitamin B12 was added at a dose of 5000 µg 4-weekly im.

However, the lower end of the CI is still at a similar range, as in other studies using Peg-IFN plus ribavirin for 48 weeks.[12] Still, the study supports earlier findings of better treatment response in patients with a vitamin B12 serum level >360 pM compared with patients with a level of ≤360 pM.[4] In addition, both of these clinical studies are concordant with the expectation of an antiviral effect based on the earlier in vitro findings of viral inhibition by vitamin B12. However, it is too early to call it a done deal. Another study, evaluated 102 patients undergoing HCV therapy with median vitamin B12 levels of 490 pg/ml and ranging from 398 to 638 pg/ml (equivalent to median of 361.62 pM and a range from 293.724 to 470.84 pM). Unfortunately, they report on homocystein levels being associated with response but did not comment on the vitamin B12 levels other than indicating that they were normal.[13]

Given the relative safety of vitamin B12, vitamin B12 supplementation warrants further evaluation to see whether those findings can be replicated and, just as importantly, whether the relevance of vitamin B12 is maintained in the setting of newer treatments such as the protease inhibitors that have become the new SOC with generally improved response rates from approximately 40% with Peg-IFN and ribavirin to approximately 65–70% when a protease inhibitor such as boceprevir or telaprevir is added to SOC.

Although unlikely, at this point it cannot be ruled out that the benefit of vitamin B12 may only exist in the setting of interferon plus ribavirin therapy. Given that vitamin B12 has been found to be antivirally active in vitro, there is a likely chance it will also be beneficial in all oral regimens against HCV. In addition, the suggested improved response in easy-to-treat patients with genotype 2/3, who have already high response rates, suggests that vitamin B12 will have a chance to also improve an already highly effective antiviral regimen.

If the role of vitamin B12 is found to be limited to interferon-based therapy, it might be of less relevance than if it was also found to augment direct antiviral therapies. With the in vitro viral inhibition of vitamin B12 alone, it is likely to remain relevant in all oral direct antiviral regimens. Concerning the in vitro data, there is, however, a concern that such data were only reported from one laboratory and have not independently been confirmed. Ideally, the combined effects of vitamin B12 with direct antiviral with or without interferon would be demonstrated in vitro.

It is a reminder of the discussion on vitamin D and response to interferon-based therapies. Vitamin D is very attractive, to explain some of the remaining response difference between African–American compared with Caucasian individuals when controlled for IL28B. Vitamin D levels are lower in African–American individuals, and they respond worse to Peg-IFN plus ribavirin, even when controlled for IL28B.

A study from Israel reported 86% (31 out of 36) SVR rates in patients treated with Peg-IFN and ribavirin plus oral vitamin D (2000 IU/d Vitamidyne D, Fischer Pharmaceuticals, Israel) versus 41% (15 out of 36) in those treated with Peg-IFN and ribavirin alone.[14] In a second study, the same team reported improved SVR rates if genotype 2/3 patients were treated with vitamin D in addition to Peg-IFN and ribavirin (19 out of 20 [95%] vs 23 out of 30 [77%]; p < 0.001).[15] Their findings are in line with a retrospective analysis of 42 patients with recurrent HCV infection after liver transplantation, where the 15 patients who received vitamin D supplementation 800 IU/d in the form of cholecalciferol showed better SVR rates than nonsupplemented patients.[16] Subsequently, it has been reported from independent groups that vitamin D (to be exact 25-hydroxyvitamin D3 [25(OH)D3]) can actually inhibit HCV replication in vitro[17,18] and that resistance development in the NS3 helicase domain of HCV in response to vitamin D dosing was observed. Resistance development is considered a good marker for true antiviral activity (i.e., versus toxicity), as resistance is only expected to emerge against antivirally active substances.

Similar to vitamin B12, it has also been reported for vitamin D that there is a correlation between vitamin D levels in the blood and response to Peg-IFN and ribavirin therapy.[19] This has subsequently been confirmed repeatedly in several studies.[20,21]

There could be a pitfall concerning vitamin D. Lange et al., in an initial study, reported both the CYP27B1-1260 promoter polymorphism (rs10877012: AA, AC and CC), which has substantial impact on 1,25-dihydroxyvitamin D serum levels (72, 61 and 60 pmol/ml for AA, AC and CC, respectively; p = 0.04) and 25-hydroxyvitamin D levels to be related to SVR in interferon-based therapy for HCV, but in their subsequent larger study, they found, in addition to the CYP27B1-1260 polymorphism, that only the bioactive vitamin D (1,25[OH]2D3, calcitriol) but not the calcitriol precursor 25(OH)D3 was predictive of response to treatment in patients with chronic hepatitis C.[20]

Thus, it will be important for future studies on vitamins to evaluate different metabolites, as not all metabolites may have the same predictive value.[21] To make things more complex, the bioactive metabolite of vitamin D (1,25[OH]2D3) was not antivirally active in a cell model where 25 (OH)D3 was active.[18]

For vitamin B12, there is also some consideration required toward the right metabolite to analyze, whether holotranscobalamin might be superior to vitamin B12 (cobalamin) levels,[22,23] or whether vitamin B12 levels should be assessed together with methylmalonic acid (or total homocysteine).[24]
Other genetic markers have yet not been confirmed, but in individual smaller studies, vitamin D receptor (NR1|1: rs1544410, rs7975232 and rs731236)[25] and CYP27B1 (rs4646536) were reported to be related to response in addition to vitamin D levels and IL28B polymorphism.[26]

Other vitamins evaluated in relation to HCV are vitamin E, β-carotine and linoleic acid. Vitamin E when combined with pentoxifylline was reported to be associated with better SVR in an Egyptian study, potentially owing to lower frequency of anemia-associated reductions of ribavirin.[27]

However, vitamin E was also reported to increase HCV replication and, therefore does not appear an attractive approach for HCV infection.[28] By contrast, β-carotine and linoleic acid both had been reported to inhibit HCV replication in vitro.[29,30] In summary, if confirmed that vitamin B12 and/or vitamin D supplementation increase response to HCV-based therapy, these might be relatively cheap ways to augment response to antiviral therapy targeting hepatitis C virus eradication.

Five-year View
Importantly, it needs to be confirmed whether vitamin B12 improves response to HCV-targeted therapy. It will be important to evaluate the role of vitamin B12 in interferon-free regimens. Given the fast development of highly active antiviral therapy regimens, which are expected to eradicate HCV in most patients within 12 weeks or shorter treatment duration in over 90% of patients, an approach that increases response rate to a side-effect-loaded therapy may be of limited attractiveness.
Given the low drug cost for vitamin D and B12 compared with direct antivirals, it might be difficult to find pharmaceutical sponsors to evaluate these approaches further. However, the development of such approaches might be more attractive for resource-limited settings, and in areas where direct antivirals are further away from daily clinical practice due to longer regulatory processes.

  1. Lott WB, Takyar SS, Tuppen J et al. Vitamin B12 and hepatitis C: molecular biology and human pathology. Proc. Natl Acad. Sci. USA 98(9), 4916–4921 (2001).
  2. Takyar SS, Gowans EJ, Lott WB. Vitamin B12 stalls the 80 S ribosomal complex on the hepatitis C internal ribosome entry site. J. Mol. Biol. 319(1), 1–8 (2002).
  3. Li D, Lott WB, Martyn J, Haqshenas G, Gowans EJ. Differential effects on the hepatitis C virus (HCV) internal ribosome entry site by vitamin B12 and the HCV core protein. J. Virol. 78(21), 12075–12081 (2004).
  4. Rosenberg P, Hagen K. Serum B12 levels predict response to treatment with interferon and ribavirin in patients with chronic HCV infection. J. Viral Hepat. 18(2), 129–134 (2011).
  5. Desombere I, Van Vlierberghe H, Couvent S, Clinckspoor F, Leroux-Roels G. Comparison of qualitative (COBAS AMPLICOR HCV 2.0 versus VERSANT HCV RNA) and quantitative (COBAS AMPLICOR HCV monitor 2.0 versus VERSANT HCV RNA 3.0) assays for hepatitis C virus (HCV) RNA detection and quantification: impact on diagnosis and treatment of HCV infections. J. Clin. Microbiol. 43(6), 2590–2597 (2005).
  6. Awad T, Thorlund K, Hauser G, Stimac D, Mabrouk M, Gluud C. Peginterferon α-2a is associated with higher sustained virological response than peginterferon α-2b in chronic hepatitis C: systematic review of randomized trials. Hepatology 51(4), 1176–1184 (2010).
  7. Ge D, Fellay J, Thompson AJ et al. Genetic variation in IL28B predicts hepatitis C treatment-induced viral clearance. Nature 461(7262), 399–401 (2009).
  8. Thompson AJ, Muir AJ, Sulkowski MS et al. Hepatitis C trials that combine investigational agents with pegylated interferon should be stratified by interleukin-28B genotype. Hepatology 52(6), 2243–2244 (2010).
  9. Jacobson IM, McHutchison JG, Dusheiko G et al.; ADVANCE Study Team. Telaprevir for previously untreated chronic hepatitis C virus infection. N. Engl. J. Med. 364(25), 2405–2416 (2011).
  10. Poordad F, McCone J Jr, Bacon BR et al.; SPRINT-2 Investigators. Boceprevir for untreated chronic HCV genotype 1 infection. N. Engl. J. Med. 364(13), 1195–1206 (2011).
  11. McHutchison JG, Lawitz EJ, Shiffman ML et al.; IDEAL Study Team. Peginterferon α-2b or α-2a with ribavirin for treatment of hepatitis C infection. N. Engl. J. Med. 361(6), 580–593 (2009).
  12. Hadziyannis SJ, Sette H Jr, Morgan TR et al.; PEGASYS International Study Group. Peginterferon-α2a and ribavirin combination therapy in chronic hepatitis C: a randomized study of treatment duration and ribavirin dose. Ann. Intern. Med. 140(5), 346–355 (2004).
  13. Borgia G, Gentile I, Fortunato G et al. Homocysteine levels and sustained virological response to pegylated-interferon α2b plus ribavirin therapy for chronic hepatitis C: a prospective study. Liver Int. 29(2), 248–252 (2009).
  14. Abu-Mouch S, Fireman Z, Jarchovsky J, Zeina AR, Assy N. Vitamin D supplementation improves sustained virologic response in chronic hepatitis C (genotype 1)-naive patients. World J. Gastroenterol. 17(47), 5184–5190 (2011).
  15. Nimer A, Mouch A. Vitamin D improves viral response in hepatitis C genotype 2–3 naïve patients. World J. Gastroenterol. 18(8), 800–805 (2012).
  16. Bitetto D, Fabris C, Fornasiere E et al. Vitamin D supplementation improves response to antiviral treatment for recurrent hepatitis C. Transpl. Int. 24(1), 43–50 (2011).
  17. Gal-Tanamy M, Bachmetov L, Ravid A et al. Vitamin D: an innate antiviral agent suppressing hepatitis C virus in human hepatocytes. Hepatology 54(5), 1570–1579 (2011).
  18. Matsumura T, Kato T, Sugiyama N et al. 25-hydroxyvitamin D(3) suppresses hepatitis C virus production. Hepatology doi:10.1002/hep.25763 (2012)(Epub ahead of print).
  19. Petta S, Cammà C, Scazzone C et al. Low vitamin D serum level is related to severe fibrosis and low responsiveness to interferon-based therapy in genotype 1 chronic hepatitis C. Hepatology 51(4), 1158–1167 (2010).
  20. Lange CM, Bibert S, Kutalik Z et al.; the Swiss Hepatitis C Cohort Study Group. A genetic validation study reveals a role of vitamin D metabolism in the response to interferon-α-based therapy of chronic hepatitis C. PLoS ONE 7(7), e40159 (2012).
  21. Lange CM, Bojunga J, Ramos-Lopez E et al. Vitamin D deficiency and a CYP27B1-1260 promoter polymorphism are associated with chronic hepatitis C and poor response to interferon-α based therapy. J. Hepatol. 54(5), 887–893 (2011).
  22. Fragasso A, Mannarella C, Ciancio A et al. Holotranscobalamin is a useful marker of vitamin B12 deficiency in alcoholics. ScientificWorldJournal 2012, 128182 (2012).
  23. Nexo E, Hoffmann-Lücke E. Holotranscobalamin, a marker of vitamin B-12 status: analytical aspects and clinical utility. Am. J. Clin. Nutr. 94(1), 359S–365S (2011).
  24. Yetley EA, Pfeiffer CM, Phinney KW et al. Biomarkers of vitamin B-12 status in NHANES: a roundtable summary. Am. J. Clin. Nutr. 94(1), S313–S321 (2011).
  25. Baur K, Mertens JC, Schmitt J et al.; Swiss Hepatitis C Cohort Study Group. The vitamin D receptor gene bAt (CCA) haplotype impairs the response to pegylated-interferon/ribavirin-based therapy in chronic hepatitis C patients. Antivir. Ther. (Lond.) 17(3), 541–547 (2012).
  26. D'Avolio A, Ciancio A, Siccardi M et al. Ribavirin pharmacokinetics and interleukin 28B plus cytochrome P450 27B1 single-nucleotide polymorphisms as predictors of response to pegylated interferon/ribavirin treatment in patients infected with hepatitis C virus genotype 1/4. Hepatology 54(6), 2278–2279 (2011).
  27. Assem M, Yousri M. Impact of pentoxifylline and vitamin E on ribavirin-induced haemolytic anaemia in chronic hepatitis C patients: an Egyptian survey. Int. J. Hepatol. 2011, 530949 (2011).
  28. Huang H, Chen Y, Ye J. Inhibition of hepatitis C virus replication by peroxidation of arachidonate and restoration by vitamin E. Proc. Natl Acad. Sci. USA 104(47), 18666–18670 (2007).
  29. Yano M, Ikeda M, Abe K et al. Comprehensive analysis of the effects of ordinary nutrients on hepatitis C virus RNA replication in cell culture. Antimicrob. Agents Chemother. 51(6), 2016–2027 (2007).
  30. Rocco A, Compare D, Coccoli P et al. Vitamin B12 supplementation improves rates of sustained viral response in patients chronically infected with hepatitis C virus. Gut doi:10.1136/gutjnl-2012-302344 (2012) (Epub ahead of print).
Source -  Medscape

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