Tag Archives: sofosbuvir

Keeping Track of HCV Trials -Three More

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Recently three more trials of all oral regimens for HCV have been published in the NEJM.  A useful summary of their effectiveness is available in the associated editorial.  Here’s the link and an excerpt:

http://nej.md/1hhae91 

Welcomed and exciting results from three large, controlled trials of different regimens of oral antiviral agents for chronic hepatitis C, genotype 1, have now been published in the Journal.1-3 The regimens all included the combination of ledipasvir and sofosbuvir, two new direct-acting antiviral agents with potent activity against hepatitis C virus (HCV). The two drugs were given as a single tablet once daily for 8, 12, or 24 weeks, with or without ribavirin. The results were consistent and striking: the various regimens yielded rates of sustained virologic response of 93% to 99%. The combination of ledipasvir and sofosbuvir alone (without ribavirin) for 12 weeks was associated with response rates of 94% in the ION-2 study and 99% in the ION-1 study.1,2 Extending therapy to 24 weeks increased the rate minimally (to 98% and 99%, respectively). In contrast, adding ribavirin provided no further benefit, regardless of duration. In previously untreated patients without cirrhosis, shortening the duration of therapy (without ribavirin) to 8 weeks did not lessen the rate of response (94%, vs. 95% with 12 weeks of therapy in the ION-1 study).3 Importantly, the single-tablet regimen was easy to administer and had few side effects; among the 539 patients who received ledipasvir and sofosbuvir alone for 12 weeks in these three trials, only 2 stopped therapy early because of adverse events.

The rates of response to ledipasvir and sofosbuvir were virtually the same in all subgroups of patients, regardless of patients’ age, sex, race, liver-enzyme levels, HCV genotype (1a vs. 1b), preexisting antiviral resistance variants, or host genetic factors. Even in the difficult-to-treat patients who had not had a sustained response to a previous course of the most effective interferon-based therapies,4 the response rate at post-treatment week 12 was 94%. In this group of patients, the presence of cirrhosis was associated with a slightly lower response rate (88%, vs. 95% without cirrhosis), but with the longer course of treatment (24 weeks), these differences disappeared (100% in both groups).2 Preliminary studies with interferon-free drug combinations in patients with other HCV genotypes (2 or 3) suggest that high rates of response can be expected with those HCV strains as well.5

The combined results of the three trials include 1952 patients, of whom 97% had a sustained virologic response. Among the 3% who did not have a response, almost half were lost to follow-up or withdrew consent… Relapses were more common with shorter courses of therapy: 5% of patients who received 8 weeks of treatment had a relapse, as did 2% of those who received 12 weeks and 0.2% of those who received 24 weeks of treatment…

Ledipasvir and sofosbuvir are not the only promising antiviral agents for hepatitis C on the near horizon. Several other all-oral antiviral regimens have performed similarly in phase 2 studies, with sustained response rates in the range of 90% or higher.6,7 Thus, there are likely to be several options for oral therapy of hepatitis C within the next year.

  1. The availability of effective, oral regimens of therapy for hepatitis C will lead to major changes in the management of this disease and probably affect both its morbidity and its mortality…The limitations and medical barriers to treatment, however, may now largely disappear. The ease of administration, short duration of treatment, and minimal side effects of all-oral regimens will probably mean that most persons will qualify for therapy. Collectively, these regimens promise to transform hepatitis C from a condition requiring complex, unsatisfactory therapies and specialist care to one that can be effectively treated and easily managed by a general physician with few contraindications and side effects.
  2. Unfortunately, not all barriers to treatment will be lifted. The major limitation remaining will be economic. The current cost of a 12-week regimen of sofosbuvir alone is $84,000, or $1,000 per tablet.11 The addition of ledipasvir will add to the costs, and these estimates do not include expenses for diagnostic assays, monitoring, and physician visits…

Costs alone cast a pall over the stunning success in achieving the long-hoped-for goal of a safe and effective therapy for hepatitis C.

References:

  1. Afdhal N, Reddy KR, Nelson DR, et al. Ledipasvir and sofosbuvir for previously treated HCV genotype 1 infection. N Engl J Med. DOI: 10.1056/NEJMoa1316366.
  2. Afdhal N, Zeuzem S, Kwo P, et al. Ledipasvir and sofosbuvir for untreated HCV genotype 1 infection. N Engl J Med. DOI: 10.1056/NEJMoa1402454.
  3. Kowdley KV, Gordon SC, Reddy KR, et al. Ledipasvir and sofosbuvir for 8 or 12 weeks for chronic HCV without cirrhosis. N Engl J Med. DOI: 10.1056/NEJMoa1402355.

Related tweets (with links to abstracts/full text) from NEJM twitter feed:

  • ION-1: Sofosbuvir and ledipasvir (12 or 24 wks) achieved high (98 or 99%) SVR rates in untreated pts w/ HCV.
  • ION-2: Sofosbuvir and ledipasvir (12 or 24 wks) achieved high SVR rates in pts w/ HCV who failed prior Tx. 
  • TURQUOISE II: SVR achieved at 12 wks in 92% of pts w/ HCV and cirrhosis, and in 96% at 24 wks.

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.

 

 

More HCV options -phase 3 for Sofosbuvir

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The pace of research for HCV is incredible.  Two months ago phase 2 data for Sofosbuvir were reported and noted on this blog (More options for Hepatitis C | gutsandgrowth).  Now phase 3 data from multiple trials have emerged indicating the effectiveness of sofosbuvir for all HCV genotypes.

In the first study, NEJM 2013; 368: 1867-77, data from two trials (POSITRON and FUSION) of patients with HCV genotypes 2 and 3 are reported.  The POSITRON trial (63 sites, n=278 received treatment) was a blinded placebo-controlled study that evaluated 12 weeks of sofosbuvir/ribavirin compared with placebo in patients who discontinued interferon due to unacceptable adverse events or could not take interferon due to contraindications (most commonly psychiatric disorder or autoimmunity). Results: sustained virological response (SVR) in 78% of treatment group compared with 0% of placebo patients.  In addition, there was “complete concordance (100%) between rates of SVR at 12 weeks and at 24 weeks.”

The FUSION study (67 sites, n=201 received treatment) was a blinded, active-control study in patients who did not respond to a previous interferon-based regimen; one of two treatment regimens were administered: 12 weeks of sofosbuvir/ribavirin followed by placebo or 16 weeks of sofosbuvir/ribavirin. Results: 93% of genotype 2 patients had SVR and 61% of genotype 3 patients had SVR.  Among cirrhotic patients, 61% had SVR (94% of genotype 2, 21% of genotype 3); for those without cirrhosis, there was an 81% SVR (92% with genotype 2, 68% with genotype 3).  Thus, it is easy to conclude that genotype 3 patients with cirrhosis responded much less favorably.

Other important findings: rates of discontinuation among the treatment groups were similar to the placebo groups.  The most common adverse effect was anemia in the treatment groups.

In the second study, NEJM 2013; 368: 1878-87, an additional two phase 2 trials (NEUTRINO and FISSION) are reported from previously untreated chronic HCV patients.  The first trial (NEUTRINO) was an open-label study examining a 12-week regimen of sofosbuvir, peginterferon alfa-2a, and ribavirin in 327 HCV patients (98% genotypes 1 or 4).  Results: SVR noted in 90%. The second trial (FISSION) enrolled 499 patients with genotypes 2 and 3 who randomly received either peginterferon alfa-2a/ribavirin for 24 weeks or sofosbuvir/ribavirin for 12 weeks. Results: SVR noted to be 67% in both groups.  Genotype 2 patients again fared better than genotype 3 among the sofosbuvir/ribavirin group (97% versus 56%).  Some adverse events like fatigue, headache and nausea were common.  Overall, side effects were much lower in those not receiving peginterferon (see Table 3).

Take home message: From the editorial (pg 1931-32 in same issue): “a radical change in clinical practice is imminent…the low incidence of side effects, the relatively short duration of treatment, and the pangenotypic properties of the drugs are strong selling points of a sofosbuvir-ribavirin regimen and will probably lower the threshold for HCV treatment for both patients and physicians.”

Hopefully, we will see pediatric studies soon.

Related blog entries:

More options for Hepatitis C

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As noted in numerous blog entries (see below), there has been increasing availability of new and more effective treatments for Hepatitis C virus (HCV).  Two more drugs have promising results:

  • NEJM 2013; 368: 34-44
  • NEJM 2013; 368; 45-53

The first study provides encouragement with regard to sofosbuvir (previously known as GS-7977) which is a direct-acting nucleotide polymerase inhibitor targeting the NS5B polymerase.

In this open-label study, there were eight groups of patients.  Of 40 previously untreated patients (genotype 2 or 3), all patients received sofosbuvir (400 mg daily) for 12 weeks.  All 10 who received the study drug with ribavirin (& without interferon) and all 30 who received the study drug with ribavirin and peginterferon had a sustained virologic response (SVR) at 24 weeks.  Among patients with sofosbuvir monotherapy, 6 of 10 had a SVR.  Among HCV genotype 1 patients, 21 of 25 (84%) previously untreated patients had a SVR. The most common adverse effects were headache, fatigue, insomnia, rash and anemia.

The second study also was a phase 2a, open-label study for HCV genotype 1 non-cirrhotic patients using ABT-333 and ribavirin.  ABT-333 is a nonnucleoside NS5B polymerase inhibitor.  Results: 17 of 19 (89%) patients in group 1 (Rx with ABT-333, ribavrin, ABT-450, and ritonavir), 11 of 14 (79%) patients in group 2 (Rx with same drugs at lower doses of latter two drugs) had extended rapid virologic response.  SVR was achieved in 95% and 93% respectively.  Groups 1 and 2 were previously untreated.  Group 3 were patients who had either a null or partial response to previous treatment achieved a 47% SVR.  The most common adverse effects were abnormalities in liver function tests, headache, fatigue, insomnia, pruritus, nausea and rash.

Bottom-line:

These preliminary results suggest that Sofosbuvir is effective in all genotypes and may allow a short duration all-oral regimen.  ABT-333 similarly is effective in an all oral regimen in genotype 1 patients.

Related blog posts: