Anadys Announces Positive 12-Week Data for Setrobuvir in Phase 2b Hepatitis C Study

Positive interim (12 week) Phase IIb data for Anadys's non nuc Setrobuvir + p/r in both treatment naive and non-responders to previous P/R. Looks to be comparable to P/R in side effect profile, except for the amount of rash (39%) (98% mild to moderate)

Anadys Announces Positive 12-Week Data for Setrobuvir in Phase 2b Hepatitis C Study

- Strong Antiviral Response in Prior Partial Responders and Relapsers - Favorable Safety Data with AE Profile Comparable to Control Group - High Barrier to Resistance Confirmed --Conference Call at 8:00 AM EDT Today

SAN DIEGO, Oct. 13, 2011 Anadys Pharmaceuticals today released interim antiviral response and safety data from an ongoing Phase IIb study of setrobuvir in combination with pegylated interferon and ribavirin (P/R) in genotype 1 hepatitis C patients. Setrobuvir is the Company's direct-acting antiviral being developed for the treatment of chronic hepatitis C, or HCV.

"We are pleased with today's data, which we believe demonstrate a compelling profile for setrobuvir in significantly more patients," said Steve Worland, Ph.D., President and CEO of Anadys. "The antiviral response in patients who had failed prior treatment is a particularly encouraging benchmark of setrobuvir's potency and high barrier to resistance. Coupled with a favorable safety profile to date, we believe today's data position setrobuvir as a very attractive agent to be included in future DAA combination regimens."

78% of treatment-naive patients and 76% of patients who had responded inadequately to, or relapsed after, prior treatment with P/R had undetectable virus at week 12 (cEVR) while receiving setrobuvir plus P/R, compared to 56% and 44%, respectively, for patients who received placebo plus P/R. 71% of treatment-naive patients who received setrobuvir plus P/R had undetectable virus at week 8 and met the initial response-guided criteria for shortening treatment in this study to 28 weeks from the traditional 48 weeks for treatment with P/R alone.

29% of patients who had no appreciable response to prior treatment with P/R (null responders) achieved cEVR with setrobuvir plus P/R, and the percentage of patients with undetectable virus continued to climb in this hard-to-treat population to 36% at week 18. No prior null responders received placebo plus P/R in this trial.

The viral breakthrough rate through 12 weeks on setrobuvir plus P/R was low in both treatment-naïve patients (2.9%) and patients who had responded inadequately to, or relapsed after, prior treatment with P/R (3.6%). The Company believes this low incidence of viral breakthrough exhibited to date in a larger patient population further characterizes setrobuvir's high barrier to resistance.

Setrobuvir has been generally well-tolerated in the study. Safety data for patients receiving setrobuvir plus P/R, and comparison to the control group that received placebo plus P/R, are being reported through a time period that reflects a median dosing duration of 19 weeks. The rate of discontinuing treatment in the study due to adverse events has been similar in patients receiving setrobuvir plus P/R (5.6%) or P/R alone (5.9%). The profile of adverse events has been similar between the setrobuvir and control groups, with reported adverse events being typical for patients treated with interferon and ribavirin. In the setrobuvir group, 39% of patients (84/215) developed a rash while 22% (15/68) of patients in the control group developed a rash. 98% of the rashes in the setrobuvir group were mild or moderate (grade 1 or grade 2), compared to 93% in the control group. There were no Grade 4 rashes in either group. The incidence of rash in the setrobuvir group is consistent with prior reports of rash due to interferon and ribavirin through 19 weeks of treatment.



Proportion of patients with undetectable virus at Week 12 (cEVR)
setrobuvir + P/R placebo + P/R
--------------------- ---------------------
Treatment-naive patients 78% 56%
----------------------------------- --------------------- ---------------------
Treatment-experienced patients
prior partial responder or relapser 76% 44%
prior null responder 29% ---
----------------------------------- --------------------- ---------------------




Phase 2b Protocol Design

283 patients were dosed in this study. Patients received either setrobuvir 200 mg twice a day (bid) in combination with Pegasys® (peginterferon alfa-2a) and Copegus® (ribavirin, USP) (P/R) with a loading dose of setrobuvir 800 mg bid on day 1, or placebo plus P/R. Patients who had a prior null response to P/R, defined as less than a 1 log10 decline in viral load at week 4 or less than a 2 log10 decline at week 12 during prior treatment, were not randomized to receive placebo. All other patients were stratified by IL28B genotype (CC/non-CC) between setrobuvir and placebo groups. The interim antiviral response data is being reported as the proportion of patients with undetectable virus (< 15 IU/mL) using the Roche COBAS HCV TaqMan assay. The primary endpoint of the study is Sustained Virological Response 24 weeks after patients conclude all treatment, known as SVR24. In addition to the interim data released today, data through 24 weeks of dosing are expected around year-end. The study is being conducted at sites in the United States, Canada, Australia and New Zealand.

Treatment-Naive Group

102 treatment-naive patients received setrobuvir plus P/R

36 treatment-naive patients received placebo plus P/R

Treatment-naive patients who achieved undetectable levels of virus by Week 8 and maintain undetectable levels of virus are scheduled to conclude all treatment at Week 28

For treatment-naive patients with detectable virus at Week 8, treatment with setrobuvir or placebo and P/R is scheduled to continue through Week 48

Treatment-Experienced Group (including prior null responders)

82 patients who were partial responders during, or relapsers after, a prior course of therapy with P/R alone received setrobuvir plus P/R

32 corresponding patients received placebo plus P/R

31 prior null responder patients received setrobuvir plus P/R

All treatment-experienced patients are scheduled to be treated for 48 weeks

About Setrobuvir

Setrobuvir is an HCV RNA polymerase inhibitor that belongs to a chemical class referred to as non-nucleosides. Setrobuvir has a well-characterized safety database in which more than 350 subjects have received the agent to date. Setrobuvir has received Fast Track Status from the FDA for the treatment of chronic hepatitis C. Earlier this year, Anadys announced a cross-company clinical trial agreement with a large, commercial-stage biopharmaceutical company to study setrobuvir in combination with another DAA in healthy volunteers.

Conference Call Webcast and Slides

Anadys will hold a conference call and webcast today, October 13, 2011 at 8:00 a.m. Eastern Daylight Time to discuss interim antiviral response and safety data from an ongoing Phase IIb study of setrobuvir in combination with P/R. A live webcast of the call, including accompanying slides, will be available online at www.anadyspharma.com . A telephone replay with slides will also be available approximately one hour after completion of the call. To access the telephone replay, dial 888-286-8010 (domestic) or 617-801-6888 (international), passcode 21814367. The webcast and telephone replay will be available through October 27, 2011.

Safe Harbor Statement

Statements in this press release that are not strictly historical in nature constitute "forward-looking statements." Such forward-looking statements include, but are not limited to, references to (i) the belief that the interim data described in this press release, coupled with a very favorable safety profile to date, position setrobuvir as a very attractive agent to be included in future DAA combination regimens, (ii) Anadys' belief that the low incidence of viral breakthrough exhibited to date further characterizes setrobuvir's high barrier to resistance, and (iii) setrobuvir's potency and adverse event profile based on the interim data reported in this press release. Such statements involve known and unknown risks, uncertainties and other factors, which may cause Anadys' actual results to be materially different from historical results or from any results expressed or implied by such forward-looking statements. For example, the results of preclinical and early clinical studies may not be predictive of future results, and Anadys cannot provide any assurances that setrobuvir will not have unforeseen safety issues, will have favorable results in ongoing or future clinical trials or will receive regulatory approval. In addition, Anadys' results may be affected by competition from other biotechnology and pharmaceutical companies, its effectiveness at managing its financial resources, its ability to enter into transactions around its product candidates, its ability to successfully develop and market products, difficulties or delays in its non-clinical studies or clinical trials, difficulties or delays in manufacturing its clinical trials materials, the scope and validity of patent protection for its products, regulatory developments and its ability to obtain additional funding to support its operations. Risk factors that may cause actual results to differ are more fully discussed in Anadys' SEC filings, including Anadys' Form 10-Q for the quarter ended June 30, 2011. All forward-looking statements are qualified in their entirety by this cautionary statement. Anadys is providing this information as of this date and does not undertake any obligation to update any forward-looking statements contained in this document as a result of new information, future events or otherwise.

Pegasys® and Copegus® are registered trademarks of Hoffman-La Roche Inc.

SOURCE Anadys Pharmaceuticals, Inc.

Copyright (C) 2011 PR Newswire. All rights reserved

Pharmasset Announces the Expansion of the ELECTRON Trial in Chronic Hepatitis C

Pharmasset adding arms to it's genotype 2/3 ELECTRON trial looking at shorter durations of therapy in addition to inteferon-free monotherapy for it's PSI-7977 nucleotide analog. Nucs traditionally have a very high barrier to resistance in comparison to non-nucs, but with a virus capable of making every possibly mutation of itself in the course of a day, is nuc monotherapy without an immune system modulator or another viral life cycle-specific inhibitor enough, even in the relatively easy-to-treat G2 and 3 virus? If it's not, what are the odds of a PSI-7977 resistant quasispecies developing and the corresponding fitness level compared to wild type of those variants? Guess we'll find out soon enough. If anyone can shed further enlightenment, please do.

PRINCETON, N.J., June 8, 2011 /PRNewswire/ -- Pharmasset, Inc. (Nasdaq: VRUS) announced today the addition of three treatment cohorts to the ELECTRON trial of PSI-7977, a nucleotide analog polymerase inhibitor, for the treatment of chronic hepatitis C (HCV). The rapid and consistent antiviral effects and high barrier to resistance demonstrated with PSI-7977 to date provide the rationale for additional exploratory regimens in this setting. This amendment will add one arm exploring 12 weeks of PSI-7977 monotherapy (without peginterferon and ribavirin) and two arms of interferon-sparing therapy: one for 8 weeks of PSI-7977 plus peginterferon and ribavirin (Peg-IFN/RBV) in patients with HCV genotype 2 (GT2) or 3 (GT3) and one for 12 weeks of PSI-7977 plus Peg-IFN/RBV in patients with HCV genotype 1 (GT1) prior null responses.

"The combination data reported at EASL demonstrated that SVRs were achievable with two oral DAAs in the absence of peginterferon and ribavirin," stated Bill Symonds, PharmD, Pharmasset's Senior Vice President of Clinical Pharmacology and Translational Medicine, "We continue to explore the potential for removing peginterferon and ribavirin from the HCV treatment regimen. Given the encouraging data we are seeing in ELECTRON, we have decided to expand the study to investigate PSI-7977 monotherapy, as well as shorter treatment regimens based on the promising data we reported at EASL from PROTON."

Pharmasset anticipates reporting results from the first four arms of the trial (n=40) during the second half of 2011. We have submitted a number of abstracts to the 2011 American Association for the Study of Liver Diseases (AASLD) meeting, including data from the ELECTRON and PROTON trials.

About the Trial

The ELECTRON trial is an exploratory study of PSI-7977 for the treatment of chronic HCV infection. Part 1 of the trial is evaluating 12-week regimens of PSI-7977 400mg QD in combination with ribavirin (RBV) only, and in separate arms with abbreviated durations of Peg-IFN for 4, 8, or 12 weeks in treatment-naive patients with HCV GT2 or GT3. The primary endpoint of the trial is the safety and tolerability of PSI-7977 400mg QD and RBV for 12 weeks, administered with or without Peg-IFN. On May 11, 2011, Pharmasset announced the completed enrollment of Part 1 of ELECTRON in patients with HCV GT 2 or GT 3:

* PSI-7977 400mg with RBV for 12 weeks (no peginterferon);
* PSI-7977 400mg with RBV for 12 weeks; Peg-IFN weeks 1-4 only;
* PSI-7977 400mg with RBV for 12 weeks, Peg-IFN weeks 1-8 only;
* PSI-7977 400mg with Peg-IFN and RBV for 12 weeks.


In Part 2 of ELECTRON, Pharmasset will enroll an additional 30 patients into exploratory regimens of monotherapy and abbreviated durations of total therapy. Following on the first four Cohorts of ELECTRON a 5th cohort will be added to explore 7977 400mg monotherapy in treatment-naive patients with HCV GT2 or GT3:

* PSI-7977 400mg monotherapy for 12 weeks.


With the previously reported 100% SVR12 in naive GT2/3 subjects in PROTON, a 6th and 7th cohort will be added to ELECTRON to explore shorter treatment durations in both GT2/3 naive subjects and HCV GT1 subjects who have documented null responses (less than 2 log(10) IU/mL reduction in HCV RNA after 12 weeks of Peg-IFN/RBV):

* PSI-7977 400mg with Peg-IFN/RBV for 8 weeks
* PSI-7977 400mg QD with Peg-IFN/RBV for 12 weeks.


About Pharmasset

Pharmasset is a clinical-stage pharmaceutical company committed to discovering, developing, and commercializing novel drugs to treat viral infections. Pharmasset's primary focus is the development of oral therapeutics for the treatment of hepatitis C virus (HCV) infection. Our research and development efforts are focused on nucleoside/tide analogs, a class of compounds which act as alternative substrates for the viral polymerase, thus inhibiting viral replication. We currently have three clinical-stage product candidates advancing in trials in various populations. Our pyrimidine, PSI-7977, an unpartnered uracil nucleotide analog, is currently under study in three Phase 2b trials in patients with HCV genotypes 1 through 6, including abbreviated duration interferon and interferon-free regimens. Our purine, PSI-938, an unpartnered guanosine nucleotide analog, recently reported safety and efficacy data from 14 days of monotherapy as well as 14 days in combination with the pyrimidine, PSI-7977. An SVR-endpoint study of the purine-pyrimidine combination is anticipated to begin in the third quarter of 2011. Mericitabine (RG7128) continues in two Phase 2b trials and one interferon-free trial being conducted through a strategic collaboration with Roche.

Contact
Richard E. T. Smith, Ph.D.
VP, Investor Relations and Corporate Communications
Office: +1 (609) 865-0693

Forward-Looking Statements

Pharmasset "Safe Harbor" Statement under the Private Securities Litigation Reform Act of 1995: Statements in this press release that are not historical facts are "forward-looking statements," that involve risks, uncertainties, and other important factors, including, without limitation, the risk of cessation or delay of any of the ongoing or planned clinical trials and/or our development of our product candidates, the risk that the results of previously conducted studies involving our product candidates will not be repeated or observed in ongoing or future studies involving our product candidates, the risk that our collaboration with Roche will not continue or will not be successful, and the risk that any one or more of our product candidates will not be successfully developed and commercialized. For a discussion of risks, uncertainties, and other important factors, any of which could cause our actual results to differ from those contained in the forward-looking statements, see the section entitled "Risk Factors" in our Annual Report on Form 10-K for the fiscal year ended September 30, 2010 and our Quarterly Reports on Form 10-Q filed with the Securities and Exchange Commission and discussions of potential risks, uncertainties, and other important factors in our subsequent filings with the Securities and Exchange Commission.

SOURCE Pharmasset, Inc.

HIV Physicians Are Cautiously Optimistic About Boceprevir, Telaprevir For HIV-HCV Co-Infected Patients

Courtney McQueen from The AIDS Beacon, interviews Dr. Kenneth Mayer from Brown University's HIV program and Dr. Bruce Bacon ce Bacon,co-director of the Liver Center at St. Louis University Medical School on the use of Telaprevir and Boceprevir in co-infected patient. It appears both are cautiously hopeful about the use of either drugs in the co-infected setting, but need to fully understand the ramifications of the final data set, that should arrive in June 2012 for telaprevir and November 2012 for boceprevir. The largest cause for caution are the known drug interactions with many of the currently marketed antiretrovirals


HIV Physicians Are Cautiously Optimistic About Boceprevir, Telaprevir For HIV-HCV Co-Infected Patients
By Courtney McQueen
Published: May 6, 2011 6:02 pm

Last week an advisory panel to the U.S. Food and Drug Administration recommended that boceprevir and telaprevir be approved for the treatment of hepatitis C. For people with HIV and hepatitis C co-infection, the new drugs are an exciting development; however, a number of studies still need to be completed before the drugs are considered for people with HIV.

“It has the potential to revolutionize care, but I think it’s just the beginning of the journey,” said Dr. Kenneth Mayer, a professor of medicine at Brown University, director of the Brown University AIDS Program, and medical research director at Fenway Community Health. Dr. Mayer was not involved with development of either of the drugs.

Dr. Mayer, who has been seeing HIV and AIDS patients since the beginning of the epidemic, thought the early results for both drugs are promising. However, he also thought a lot more research needs to be done before clinicians can feel comfortable prescribing the drugs to people with HIV.

“The vast majority of the studies so far are in mono-infected individuals [people with hepatitis C only], so I think there’s a bunch of questions that have to be answered before we’re sure of how to use these drugs best for people with HIV,” he said.

If the Food and Drug Administration (FDA) approves the drugs, they could be available to patients as soon as late May. Although the FDA is not required to follow the recommendations of its advisory committees, it usually does.

For People With HIV, Boceprevir And Telaprevir Clinical Trials Are Still In Early Stages

The approval recommendations from last week are based on Phase 3 clinical trials in people infected only with hepatitis C virus (HCV). The trials showed that adding boceprevir or telaprevir to standard HCV treatment raised cure rates from about 40 to 45 percent to about 65 to 80 percent.

Standard HCV treatment consists of 48 weeks of ribavirin (Rebetol, Copegus) plus Pegasys (pegylated interferon alfa-2a) or PegIntron (pegylated interferon alfa-2b). Typically, standard HCV treatment is less effective in people who are also infected with HIV (see related AIDS Beacon news).

For people with HIV, the benefits of the new drugs are not clear yet. Both drugs are currently in Phase 2 clinical trials for people who are co-infected with HIV and HCV, with estimated trial completion dates of June 2012 for telaprevir and November 2012 for boceprevir.

Dr. Bruce Bacon, a professor of internal medicine and co-director of the Liver Center at St. Louis University Medical School, was involved in clinical trials for both drugs and expressed optimism about their success in co-infected patients.

“Definitely the cure rates, or sustained virologic response, for co-infected patients will be significantly improved with either boceprevir or telaprevir. How much they will be improved, I don’t know yet,” he said.

Preliminary results for telaprevir were presented in March at the Conference on Retroviruses and Opportunistic Infections (see related AIDS Beacon news). Results at that time were promising; 70 percent of HIV-HCV patients receiving telaprevir in addition to standard therapy of ribavirin and Pegasys had undetectable HCV levels after four weeks, compared to 5 percent of patients receiving the placebo plus standard therapy.

Among the participants who received telaprevir for 12 weeks, 68 percent had undetectable HCV levels, compared to 14 percent of participants receiving ribavirin plus Pegasys alone. However, not all participants had reached 12 weeks of treatment by the time of the analysis.

Additionally, overall hepatitis C cure rates were not yet available. Clinicians consider a patient to be cured of hepatitis C if the virus remains undetectable for 24 weeks after stopping treatment (called a sustained virologic response).

Dr. Bacon stated that the telaprevir results should be taken with caution. “That’s pretty early data. I think it’s probably a little too early to know the significance of [the telaprevir results],” he said.

Results for boceprevir in people who are HIV-HCV co-infected are not yet available.

For people with HIV-HCV co-infection, the lack of definitive results means that some patients may need to decide whether to take the drugs when they become available, or wait until the clinical trials are complete and physicians have more information on the drugs’ efficacy and safety in people with HIV.

“If a person is not in acute need of treatment, it may be prudent to wait, to know how to best manage [treatment],” said Dr. Mayer.

“The initial guidelines will not recommend these drugs for co-infected people until there is more data, so there would also be a question of whether third party payers or insurers would reimburse for the cost of the medications, and I’m sure that the cost of the medications would be considerable,” he added.

Dr. Bacon stated that he was likely to start prescribing the drugs without waiting for all of the clinical trial results. “I have a large number of co-infected patients who are waiting for treatment, and I’m probably not going to wait until the results of all the studies are done. But I do need to make sure that I find out about the drug-drug interaction issues,” he said.

More Data Needed On Drug Interactions, Safety In People With HIV

Both Dr. Mayer and Dr. Bacon agreed that one of the main concerns for people with HIV will be the safety of the drugs and whether they interact with HIV medications.

“I’m hoping that there will be a very robust program of research for dually infected individuals, so we can get a better sense of the expanded safety profile of these drugs,” said Dr. Mayer.

Both boceprevir and telaprevir have associated side effects, such as anemia and rash (see related AIDS Beacon news). The Phase 2 trials in co-infected people should demonstrate whether these side effects are more common or more severe in people with HIV.

In addition, the clinical trials that are underway for both drugs will monitor how they interact with common HIV antiretrovirals. For example, researchers will test whether the hepatitis C drugs affect the concentrations of antiretrovirals in the bloodstream – either decreasing them, which would make them less effective against HIV, or increasing them, which could cause greater side effects.

They will also test whether the antiretrovirals, in turn, affect the hepatitis C drugs and their efficacy. If drug interactions are found, dosages of either the hepatitis C drugs or certain antiretrovirals may need to be adjusted for people with HIV.

For telaprevir, there are some preliminary indications that there might be interactions with certain antiretrovirals, namely protease inhibitors boosted with Norvir (ritonavir). It is not clear yet whether these will require dosage adjustments of either telaprevir or the protease inhibitors in patients taking these drugs.

No information is available yet on drug interactions for boceprevir.

People With HIV Should Get Tested – And Retested – For Hepatitis C

With the two new drugs potentially available in the near future, both physicians urged people with HIV to get tested for HCV so they can start treatment if necessary.

“This underscores the importance of everybody who’s HIV infected to know their hepatitis C status. If somebody has engaged in any behaviors that might put them at risk for acquiring hepatitis C, they should be retested,” said Dr. Mayer.

“Even if somebody is not going to start these medications tomorrow, we are getting into the mode where, fairly soon, we’ll be able to start treating hepatitis C earlier,” he added.

Hepatitis C is spread in much the same way as HIV – unprotected sexual intercourse, sharing of needles, and other exposures to infected bodily fluids.

Dr. Bacon said patients who are co-infected should not avoid treatment.

“If they do know that they’re co-infected, they should know that there’s something that will be better than what there used to be. They ought to see a specialist who is knowledgeable about [the new drugs], and they ought to be treated,” said Dr. Bacon.

“I think it’s a new era for hepatitis C patients, and it will be a new era for co-infected patients as well,” he added.

Next Steps For Hepatitis C Treatment

Researchers have already begun to discuss the next phases of hepatitis C treatment. Both Dr. Mayer and Dr. Bacon were optimistic about the future for people with hepatitis C and HIV-HCV co-infection.

“Hopefully in the next few years we’ll be in the position to have a lot of different choices, much in the same way that we have for HIV,” said Dr. Mayer.

Dr. Bacon agreed. “Most people feel that there will be new regimens that are going to be used, and both telaprevir and boceprevir, as first generation protease inhibitors, will be replaced by second and third generation drugs and different regimens. Hopefully interferon-free regimens,” he said.

Interferon (Pegasys or PegIntron), which is part of the current standard treatment regimen for hepatitis C, is difficult to take (it must be injected, usually once a week) and is associated with many side effects.

“I think we’re within a couple of years of having large studies with non-interferon based treatment that will be successful,” said Dr. Bacon.

Original article: http://www.aidsbeacon.com/news/2011/05/06/hiv-aids-physicians-are-cautiously-optimistic-about-boceprevir-telaprevir-for-hiv-hcv-co-infected-patients/

Modeling data shows that Telaprevir increases second-phase HCV decline...

Predictive models make me nervous, especially those with the word "new" in front of them because I always think of the one person who might take this study as gospel and actually treat accordingly. But this data, (published online in the journal Hepatology) using a new predictive model, does offer a plausible hypothesis - that the steep decline in the second phase viral clearance is responsible for the shortened duration of therapy with Telaprevir and, assuming high compliance and no resistance, HCV viral particles could be cleared in as little as seven weeks. Compelling, because we've heard of patients who had truncated durations of therapy with Telaprevir + Peg & Riba and still clear virus. Interesting, but again, only a model.

Telaprevir Increases Second-Phase Hepatitis C Decline

Predictive model indicates virus particles could be cleared in seven weeks assuming high compliance


Analysis of the kinetics of telaprevir treatment for hepatitis C virus shows a rapid second-phase viral decline, which may allow for shorter duration of treatment, according to a study published online March 7 in Hepatology.

FRIDAY, April 8 (HealthDay News) -- Analysis of the kinetics of telaprevir treatment for hepatitis C virus (HCV) shows a rapid second-phase viral decline, which may allow for shorter duration of treatment, according to a study published online March 7 in Hepatology.

Jeremie Guedj, Ph.D., and Alan S. Perelson, Ph.D., from the Los Alamos National Laboratory in New Mexico, examined second-phase HCV viral decline during treatment with telaprevir. Two aspects of telaprevir treatment were investigated: the effect of varying regimens of telaprevir monotherapy in 28 participants, and the comparison of telaprevir monotherapy in eight patients with telaprevir plus interferon therapy in eight patients. Using a new viral kinetic model, and assuming that drug resistance can be avoided, the treatment time needed to eliminate all virus and infected cells was estimated.

The investigators found that the second-phase viral decline was associated with the effectiveness of treatment, and was approximately four times more rapid with telaprevir than interferon-based therapies. In the predictive model, assuming 95 percent of the patients are fully compliant, the last virus particle could be eliminated within seven weeks, and the clearance of remaining infections in the hepatocytes by no more than 10 weeks. This time would be extended if doses were missed.

"Using a new viral kinetic model that allowed for an improved description of the changes in antiviral treatment effectiveness, the second phase of viral decay was found to be very rapid compared with second phases observed in patients treated with interferon alone, with no differences according to the treatment regimen," the authors write.