Tag Archives: faldeprevir

Big Interferon-free Hepatitis C Study

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Every week there is more information on clinical trials for hepatitis C; I am waiting for this to translate into improvements for the pediatric population.

This week’s biggest publication: NEJM 2013; 369: 630-9.  This was a phase 2b randomized open-label trial of faldaprevir (a NS3/4A protease inhibitor) in combination with deleobuvir (a non nucleoside NS5B polymerase inhibitor).  In total, 5 different regimens were examined, most in combination with ribavirin.  The authors recruited 362 HCV genotype 1 patients who were randomized into these treatment groups & he sustained virologic response 12 weeks after completion of therapy

  • Faldaprevir 120 daily, deleobuvir 600 three times a day, and ribavirin for 16 weeks (TID16W) –>59%
  • Faldaprevir 120 daily, deleobuvir 600 three times a day, and ribavirin for 28 weeks (TID28W) –>59%
  • Faldaprevir 120 daily, deleobuvir 600 three times a day, and ribavirin for 40 weeks (TID40W) –>52%
  • Faldaprevir 120 daily, deleobuvir 600 two times a day, and ribavirin for 28 weeks (BID28W) –>69%
  • Faldaprevir 120 daily, deleobuvir 600 three times a day, without ribavirin for 28 weeks  (TID28W-NR) –>39%

Rates of SVR were higher among genotype 1b, 56-85%, compared with 1a, 38-43% (when excluding non-ribavirin group).  Genotype 1a patients with IL28B CC had similar response (58-84%) to genotype 1b patients.  Genotype 1a patients were much more likely to relapse if not treated for at least 28 weeks.

Adverse effects were common and reported in 94% of participants; 9% had severe adverse reactions.  Gastrointestinal and dermatologic advents events were the most frequent.  Also, faldaprevir resulted in jaundice (unconjugated hyperbilirubinemia) in many patients (16-28% of patients who took ribavirin in their regimens).

This large study showed that when these oral antiviral are used in combination with ribavirin that results are similar to current standard of care treatments for adult patients.  For telaprevir or boceprevir, along with pegylated interferon and ribavirin, phase 3 trials showed SVRs between 68-75%.

Related blog posts:

Emerging Targets for Hepatitis C -Part 2

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The best review on new therapies for HCV that I’ve read in quite a long time:

Hepatology 2013; 58: 428-38

First the abbreviations:

  • ASV -Asunaprevir
  • BOC -boceprevir
  • DAA -direct-acting antiviral
  • DCV -daclatasvir
  • DNV -danoprevir
  • NI -nucleos(t)ide inhibitor
  • NNI -nonnucleos(t)ide inhibitor
  • SIL -silibinin
  • SOF -sofosbuvir
  • TVR -telaprevir

More terminology:

  • First-generation NS3/4A protease inhibitors (TVR, BOC) are “defined as agents that display potent activity on HCV-1 but oppose a low barrier to selection of resistant viral variants and are not effective on all viral genotypes.”
  • Second generation NS3/4A protease inhibitors are “defined as agents that pose a high barrier to the development of viral resistance, retain activity against the viral variants that are resistant to first-generation compounds, and are active across all HCV genotypes.”
  • First-wave therapies are covalent linear inhibitors and second-wave therapies are either non covalent linear or macrocyclic inhibitors.

What are the weapons?

Some second-wave, first generation NS3/4A PIs: faldaprevir, asunaprevir, sovaprevir, simeprevir, danoprevir, and vaniprevir.  These agents have similar clinical efficacy as BOC and TVR but are easier to administer, usually once-a-day.  Some of these agents have better activity  against several genotypes.

MK-5172, 2nd-generation NS3/4A PI,  has pan-genotype activity & maintains antiviral activity against most mutations that confer resistance to 1st-generation PIs.

DCV, a NS5A inhibitor, has potent HCV activity but a low barrier for viral resistance; thus, it is likely to be used in combination with other agents.  Multiple NS5A inhibitors are in development.

SOF, a NS5B polymerase inhibitor, is being studied in interferon-free combinations.  Viral resistance has been rare in clinical studies with this agent.  Multiple other agents in this class are in study.

NS5B polymerase inhibitor NNIs bind to less conserved sites on HCV; thus, initial results have not been as promising.  Several NNIs, including setrobuvir and lomibuvir (& others), are being tested in combination in all-oral, interferon-free regimens.

SIL, a NS4B binding inhibitor, is an intravenous agent that has shown some efficacy in liver transplant patients.  Other oral agents, like clemizole, are being investigated.

How these agents may be useful:

  1. “The first step forward in anti-HCV therapy will be the introduction of a second-wave PI to used in combination with PEG-IFN/RBV.” Simeprevir, faldaprevir, and ritonavir-boosted danoprevir (DNV) will be easier to administer than TVR or BOC as they can be given once-daily.  In addition, these drugs are more active against genotypes 2, 4, 5, and 6.  In fact, ritonavir-boosted DNV in combination with PEG-IFN/RBV had 100% SVR efficacy for patients with HCV-4 in one trial.
  2. Next, will be NS5A and NS5B inhibitors to be used in combination with previous agents.  These agents will compete with second-wave PIs but “whether they will provide a true innovation in terms of viral cure rates, safety profile, or patient tolerability is still to be demonstrated.”  These agents work better with other DAAs.
  3. Finally, all-oral combinations will enter the market.  “The first all-oral anti-HCV regimen will be likely available in 2014 for HCV-2 and HCV-3 patients.”  SOF with RBV has had good success rates in previous studies.

Potential Problems:

  • Many of these investigational agents have been studied in easy-to-cure populations.
  • Lack of data in advanced fibrosis/cirrhosis.
  • Safety questions in post-transplant populations.
  • Affordability.  “It is possible that these innovative regimens will be confined to groups of patients in whom TVR/BOC or PEG-IFN/RBV are either ineffective or unsafe.”  Some patients may receive ‘maginally less effective and less tolerable drugs for cost-containing issues.’
  • Drug resistance.  This is likely to become a clinical problem with all oral IFN-free regimens. with TVR/BOC, resistance has limited significance due to HCV quasispecies reverting back to wild-type virus after stopping TVR or BOC.  It is unclear if this will be the case with other DAAs.