Pharmasset, Gilead Say Trial Change Won't Affect Takeover

Dec. 16 (Bloomberg) -- Pharmasset Inc., the company that has agreed to be bought by Gilead Sciences Inc., said it will modify the design of a hepatitis-C trial after one of its experimental drugs was linked to liver-function abnormalities.

Both companies said they don't expect the trial change to affect the deal. Pharmasset, of Princeton, New Jersey, will halt treatment arms that used a drug known as PSI-938, while continuing to test PSI-7977, another compound it is developing, the company said today in a statement.

Gilead, the world's largest maker of HIV medicines, agreed to spend $10.8 billion to buy Pharmasset to ward off rival bidders and bolster its roster of potential therapies, Gilead President and Chief Operating Officer John Milligan said in an interview last month. Gilead, based in Foster City, California, is betting that Pharmasset's treatments will lead a hepatitis C market that may reach $20 billion by 2020.

“Since this does not impact the development of PSI-7977, we do not believe the fundamental value of the deal has been impacted, and we remain committed to and look forward to completing the deal,” Amy Flood, a spokeswoman for Gilead, said today in an e-mail.

The study-design change doesn't trigger a “key product event” clause in the takeover agreement, Pharmasset said in its statement. The company doesn't have additional comment, said Andrew Cole, an outside spokesman.

Phase 2 Study

In the Phase 2 study, there were 235 participants treated with PSI-938 alone, or in combination with Pharmasset's PSI-7977, the company said. While liver abnormalities were observed in those groups, they weren't detected in patients who took PSI-7977 without PSI-938.

“This will not affect the transaction between Pharmasset and Gilead” because the deal is “based solely on PSI-7977,” Yaron Werber, an analyst for Citigroup Inc. in New York, said today in a note to clients. “There is a fair amount of data already with PSI-7977 and the drug looks clean.”

Both drugs are part of a class of compounds known as nucleotide analogs that are designed to prevent viruses from replicating.

“Based on our read of the deal terms and our conversation with Gilead this morning, we do not believe today's development poses any risk to the deal going through” at a price of $137 a share, Brian Abrahams, a New York-based analyst at Wells Fargo & Co., said today in a note to clients.

Pharmasset declined 3.2 percent to $123.75 at the close in New York. Gilead dropped 3.5 percent to $37.16.

The Pharmasset announcement may have negative implications for Inhibitex Inc. and Idenix Pharmaceuticals Inc. Those companies are developing drugs “with similar structures” to PSI-938, Abrahams said.

Inhibitex, based in Alpharetta, Georgia, plunged 20 percent to $10.45, the biggest drop since Dec. 14, 2010. Idenix, based in Cambridge, Massachusetts, fell 8.6 percent to $7.09.

--With assistance from Ryan Flinn in San Francisco and Catherine Larkin in Indianapolis. Editors: Bruce Rule, Chris Staiti

Source

Also See: Pharmasset Announces Intent to Amend QUANTUM Trial

Funding for Domestic HIV/AIDS Programs Largely Maintained by Federal Spending Bill

Policy Rider Impedes Prevention and Fails to Adequately Address ADAP Wait Lists

WASHINGTON, Dec. 16, 2011 /PRNewswire-USNewswire/ -- "Progress in preventing HIV in the United States will be set back, while little will be done to provide additional care and treatment to people already living with HIV/AIDS in our country," said Carl Schmid, Deputy Executive Director of The AIDS Institute, commenting on the final Fiscal Year 2012 spending bill to be voted on by Congress today. "This is especially disappointing in light of the optimism expressed by national and global leaders just two weeks ago on World AIDS Day," he continued.

At the insistence of the House of Representatives, the bill would reinstate a federal funding ban of syringe exchange programs, a scientifically proven method to prevent HIV and other blood borne infections, while not increasing drug use. Additionally, the bill would resurrect failed abstinence-only-until-marriage programs, but only at a minimal level of $5 million.

Despite an estimated 50,000 new HIV infections each year and over 240,000 people unaware of their infection, funding for HIV prevention at the Centers for Disease Control and Prevention (CDC) would be cut by $10 million. Surprisingly, this cut would be to its school health HIV program. The CDC reports that young people aged 13–29 accounted for 39% of all new HIV infections in 2009.

The bill flat funds the Ryan White HIV/AIDS Program except for a $15 million increase, originally proposed by the Senate, for the AIDS Drug Assistance Program (ADAP). The Ryan White Program provides care and treatment to over 550,000 low-income people with HIV/AIDS. According to NASTAD, there are currently 4,155 people in 12 states on ADAP waiting lists and over 445 people in six states who have been disenrolled from the program due to budget constraints and growing enrollment.

On World AIDS Day, President Obama, recognizing the need for additional funding for both care and treatment for low income people with HIV/AIDS in the U.S., announced $50 million in additional funds for the Ryan White Program. As part of that announcement, ADAP would receive an additional $35 million. While it is not known yet how the funds will be distributed, taken together, the $50 million in new ADAP money could eliminate the ADAP wait lists if it is distributed to the wait list states.

"We are extremely grateful to both President Obama and the Congress for continuing to recognize the importance of providing medications to people with HIV/AIDS and the serious funding gap for ADAP," commented Michael Ruppal, Executive Director of The AIDS Institute. "While it is far from enough to meet the growing need, these increases are a very positive development." According to HRSA data, the number of ADAP clients served nationally has grown an astounding 40 percent from FY07-CY10.

Under the bill, funding for medical research at the National Institutes of Health would increase by $299 million.

The final bill, which is a product of negotiation between the House and the Senate, is far better than the one introduced earlier this year by House Labor, HHS, Education and Related Agencies Appropriations Subcommittee Chairman Denny Rehberg. That bill would have decimated the Teen Pregnancy Prevention Program by cutting its budget from $105 million to $20 million, eliminate all Title X spending, and the entire Prevention and Public Health Fund. Additionally it would have prevented implementation of much of the Affordable Care Act.

The bill also includes an across the board 0.189 percent cut, meaning all programs are subject to being cut even further.

The AIDS Institute is a national nonprofit organization that promotes action for social change through public policy research, advocacy and education.

For more information and to become involved in AIDS advocacy work, please contact The AIDS Institute at: (202) 835-8373, or by email at: Info@theaidsinstitute.org or www.TheAIDSInstitute.org

SOURCE The AIDS Institute

RELATED LINKS
www.TheAIDSInstitute.org

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NIH to Limit Use of Chimps in Research

By John Gever, Senior Editor, MedPage Today
Published: December 16, 2011

The National Institutes of Health (NIH) is halting new grants for research using chimpanzees while the agency develops policies on such studies, NIH Director Francis Collins, MD, PhD, announced Thursday.

He said he had decided to follow recommendations by an Institute of Medicine (IOM) panel, also released Thursday, that called for strict limits on research use of chimps.

"Most current use of chimpanzees for biomedical research is unnecessary," the IOM report concluded. The panel found that nearly all such studies could have been performed in other ways or skipped entirely.

According to the report, research on chimps should meet each of the following criteria:

• No other suitable animal or in vitro model is available
• Conducting the study in humans would be unethical
• Not conducting the study in chimps would "significantly slow or prevent important advancements" involving serious human diseases

The panel gave broader latitude to genomic studies involving chimps, but still insisted that they be performed as a last resort and only when sample collection is "minimally invasive" and "minimizes pain and distress."

In accepting the recommendations, Collins said in a statement that previous research on chimps had been valuable.

"However, new methods and technologies developed by the biomedical community have provided alternatives to the use of chimpanzees in several areas of research," he said.

Areas where the IOM committee still saw value in chimp-based studies included research on certain monoclonal antibody therapies, social behaviors, and comparative genomics.

One hot topic in which the committee failed to reach consensus was on the use of chimps to study vaccines to prevent hepatitis C virus (HCV) infection.

Chimps are the only nonhuman species that can be infected with HCV.

"The committee agreed that it would be possible and ethical to test a prophylactic vaccine in humans without prior testing in chimpanzees, provided it was first shown to be safe in other animals," according to the IOM report.

"However, the committee was split on whether use of chimpanzees is required to rule out candidate products with lesser potential before costly and time-consuming human clinical trials, or whether such testing would provide otherwise unattainable information on the safety of candidate vaccines."

The report added that, in panel members' opinions, therapeutic anti-HCV vaccines and drugs could be developed without chimpanzees.

Collins said he would appoint a working group at NIH to propose specific polices for implementing the IOM recommendations.

The group also will advise on what to do with existing chimp colonies owned or supported by the NIH.

"We will not issue any new awards for research involving chimpanzees until processes for implementing the recommendations are in place," Collins said.

John VandeBerg, PhD, director of the Southwest National Primate Research Center in San Antonio, Texas -- home to one of the largest chimpanzee research colonies -- did not object to the recommendations.

In a statement, VandeBerg said he expected that the NIH working group "will help us in our ongoing efforts to ensure that research conducted with chimpanzees is both necessary and appropriate."

He also noted that chimpanzees have been irreplaceable in developing vaccines against hepatitis B virus, a point acknowledged in the IOM report as well. Although VandeBerg did not say so outright, he seemed to be hinting that such research should not be on NIH's chopping block.

Source

Pharmasset Announces Intent to Amend QUANTUM Trial

PRINCETON, N.J., Dec. 16, 2011 /PRNewswire/ -- Pharmasset, Inc. (Nasdaq: VRUS) announced today that the company will amend the design of the QUANTUM Phase 2b trial of the guanine nucleotide analog PSI-938 and discontinue all treatment arms with a regimen containing PSI-938. There are 235 individuals with hepatitis C virus (HCV) in the study who are receiving treatment with PSI-938 alone or in combination with PSI-7977 or PSI-7977 and ribavirin. During routine safety monitoring, the company detected laboratory abnormalities associated with liver function in subjects receiving PSI-938 300 mg once daily. These laboratory abnormalities have not been observed in patients receiving PSI-7977 and ribavirin in the QUANTUM study or in other trials evaluating PSI-7977. Both the 12 and 24-week PSI-7977 and ribavirin arms will continue unchanged, data from which will support NEUTRINO, an interferon free, 12-week Phase 3 study of PSI-7977 and ribavirin in patients with HCV genotype 1 (GT-1).

The subject of today's announcement does not trigger the "key product event" clause set forth in section 4.1(t) of the Agreement and Plan of Merger entered into by Pharmasset and Gilead Sciences, Inc. on November 21, 2011 and does not alter either party's rights and obligations under the terms of the agreement. Pharmasset anticipates that the transaction announced on November 21, 2011 will conclude in the first quarter of 2012.

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 two clinical-stage product candidates advancing in trials in various populations. Our pyrimidine, PSI-7977, an unpartnered uracil nucleotide analog, is currently being studied in an interferon-free, Phase 3 program (FISSION and POSITRON) and in five Phase 2b trials in subjects with all HCV genotypes. Mericitabine (RG7128) continues in multiple 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, 2011 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.

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Merck Announces Initiation of Clinical Development Collaboration with Roche To Evaluate Investigational Combination Regimens for the Treatment of Chronic Hepatitis C Genotype 1 Infection

Posted December 16, 2011

New Clinical Trial Will Evaluate an Investigational Therapeutic Regimen with VICTRELIS^TM (boceprevir)

WHITEHOUSE STATION, N.J., Dec. 15, 2011 - Merck (NYSE: MRK), known as MSD outside the United States and Canada, announced today that Merck, in collaboration with Roche (SIX: RO, ROG; OTCQX: RHHBY), has initiated the first of a series of planned clinical trials to examine novel combinations of marketed and investigational medicines to expedite the availability of potential new treatment regimens for patients with chronic hepatitis C virus (HCV) genotype 1 infection. Clinical development collaboration is part of the overarching strategic agreement between Merck and Roche to improve treatment, diagnosis and awareness of chronic HCV in developed and emerging markets.

"VICTRELIS is the first in a new class of medicines for the treatment of chronic HCV genotype 1 infection, and when used in combination with peginterferon alfa, can significantly increase a patient's chance of achieving undetectable levels of the virus," said Eliav Barr, M.D., vice president, Infectious Diseases Project Leadership and Management, Merck Research Laboratories. "The start of this new study is an important milestone in our collaboration with Roche as we work to build on the innovative platform VICTRELIS provides by evaluating it in combination therapy with new investigational medicines for the treatment of chronic HCV genotype 1 infection, and also emphasizes our ongoing commitment to seeking novel treatment options for patients with chronic HCV."

The first trial is designed to provide clinical data on the use of VICTRELIS^TM (boceprevir), an oral HCV NS3/4A protease inhibitor, in combination with mericitabine (RO5024048), Roche's investigational oral HCV NS5B nucleoside polymerase inhibitor, Pegasys® (pegylated interferon alfa-2a) and Copegus® (ribavirin), in adult patients with chronic HCV genotype 1 infection who had a null response to prior peginterferon alfa and ribavirin therapy (less than a 2 log HCV-RNA decline at treatment week 12). The Phase II study, called DYNAMO 1, plans to recruit patients at 25 sites globally. For further details of the clinical trial please visit www.clinicaltrials.gov , or contact (888) 662-6728 or Genentechclinicaltrials@drug info.com.

Indications and usage for VICTRELIS
VICTRELIS was approved by the U.S. Food and Drug Administration (FDA) on May 13, 2011 for the treatment of chronic hepatitis C virus (HCV) genotype 1 (G1) infection, in combination with peginterferon alfa and ribavirin (P/R), in adult patients (18 years and older) with compensated liver disease, including cirrhosis, who are previously untreated or who have failed previous interferon and ribavirin therapy.

The following points should be considered when initiating VICTRELIS for treatment of chronic HCV infection:

VICTRELIS must not be used as monotherapy and should only be used in combination with peginterferon alfa and ribavirin.

VICTRELIS efficacy has not been studied in patients who have previously failed therapy with a treatment regimen that includes VICTRELIS or other HCV NS3/4A protease inhibitors.

VICTRELIS in combination with peginterferon alfa and ribavirin has not been studied in patients documented to be historical null responders (less than a 2 log HCV-RNA decline by treatment week 12) during prior therapy with peginterferon alfa and ribavirin. The clinical studies included patients who were poorly interferon responsive. Patients with less than 0.5 log HCV-RNA decline in viral load at treatment week 4 with peginterferon alfa plus ribavirin alone are predicted to have a null response (less than a 2 log viral load decline by treatment week 12) to peginterferon alfa and ribavirin therapy.

Poorly interferon responsive patients who were treated with VICTRELIS in combination with peginterferon alfa and ribavirin have a lower likelihood of achieving a sustained virologic response (SVR), and a higher rate of detection of resistance-associated substitutions upon treatment failure, compared to patients with a greater response to peginterferon alfa and ribavirin.

Important safety information about VICTRELIS
All contraindications to peginterferon alfa and ribavirin also apply since VICTRELIS must be administered with peginterferon alfa and ribavirin. Because ribavirin may cause birth defects and fetal death, VICTRELIS in combination with peginterferon alfa and ribavirin is contraindicated in pregnant women and in men whose female partners are pregnant. Avoid pregnancy in female patients and female partners of male patients. Patients must have a negative pregnancy test prior to therapy; have monthly pregnancy tests; and use two or more forms of effective contraception, including intrauterine devices and barrier methods, during treatment and for at least 6 months after treatment has concluded. Systemic hormonal contraceptives may not be as effective in women while taking VICTRELIS and concomitant ribavirin.

VICTRELIS is contraindicated in coadministration with drugs that are highly dependent on CYP3A4/5 for clearance, and for which elevated plasma concentrations are associated with serious and/or life-threatening events. VICTRELIS also is contraindicated in coadministration with potent CYP3A4/5 inducers where significantly reduced VICTRELIS plasma concentrations may be associated with reduced efficacy. Drugs that are contraindicated with VICTRELIS include: alfuzosin, carbamazepine, phenobarbital, phenytoin, rifampin, dihydroergotamine, ergonovine, ergotamine, methylergonovine, cisapride, St. John's Wort (hypericum perforatum), lovastatin, simvastatin, drosperinone, Revatio® (sildenafil) or Adcirca® (tadalafil) (when used for the treatment of pulmonary arterial hypertension), pimozide, triazolam, and orally administered midazolam.

Anemia and neutropenia have been reported with peginterferon alfa and ribavirin therapy. The addition of VICTRELIS to peginterferon alfa and ribavirin is associated with an additional decrease in hemoglobin concentrations compared to peginterferon alfa and ribavirin alone and/or may result in worsening of neutropenia associated with peginterferon alfa and ribavirin therapy alone. Dose reduction or discontinuation of peginterferon alfa and/or ribavirin may be required. Dose reduction of VICTRELIS is not recommended. VICTRELIS must not be administered in the absence of peginterferon alfa and ribavirin.

Complete blood counts (with white blood cell differential counts) must be conducted in all patients prior to initiating combination therapy with VICTRELIS. Complete blood counts should be obtained at treatment weeks 4, 8 and 12, and should be monitored closely at other time points, as clinically appropriate.

The most commonly reported adverse reactions (greater than 35 percent) in clinical trials in adult patients receiving the combination of VICTRELIS with peginterferon alfa and ribavirin were fatigue, anemia, nausea, headache and dysgeusia. Of these commonly reported adverse reactions, fatigue, anemia, nausea, and dysgeusia occurred at rates greater than or equal to 5 percent above the rates for peginterferon alfa and ribavirin alone in either clinical study. The incidence of these adverse reactions in previously untreated patients who were treated with combination therapy with VICTRELIS compared with peginterferon and ribavirin alone were: fatigue (58 vs. 59 percent), anemia (50 vs. 30 percent), nausea (46 vs. 42 percent) and dysgeusia (35 vs. 16 percent), respectively. The incidence of these adverse reactions in previous treatment-failure patients who were treated with combination therapy with VICTRELIS compared with peginterferon and ribavirin alone were: fatigue (55 vs. 50 percent), anemia (45 vs. 20 percent), nausea (43 vs. 38 percent) and dysgeusia (44 vs. 11 percent), respectively.

VICTRELIS is a strong inhibitor of CYP3A4/5 and is partly metabolized by CYP3A4/5. The potential for drug-drug interactions must be considered prior to and during therapy.

Please see U.S. prescribing information at: http://www.merck.com/product/usa/pi_circulars/v/victrelis/victrelis_pi.pdf.

Merck's global commitment to advancing hepatitis therapy
Merck is committed to building on its strong legacy in the field of viral hepatitis by continuing to discover, develop and deliver vaccines and medicines to help prevent and treat viral hepatitis. In hepatitis C, company researchers developed the first approved therapy for chronic HCV in 1991 and the first combination therapy in 1998. In addition to ongoing studies with VICTRELIS, extensive research efforts are underway to develop additional innovative oral therapies for viral hepatitis care.

About Merck
Today's Merck is a global healthcare leader working to help the world be well. Merck is known as MSD outside the United States and Canada. Through our prescription medicines, vaccines, biologic therapies, and consumer care and animal health products, we work with customers and operate in more than 140 countries to deliver innovative health solutions. We also demonstrate our commitment to increasing access to healthcare through far-reaching policies, programs and partnerships. For more information, visit www.merck.com and connect with us on Twitter, Facebook and YouTube.

Forward-Looking Statement
This news release includes "forward-looking statements" within the meaning of the safe harbor provisions of the United States Private Securities Litigation Reform Act of 1995. Such statements may include, but are not limited to, statements about the benefits of the merger between Merck and Schering-Plough, including future financial and operating results, the combined company's plans, objectives, expectations and intentions and other statements that are not historical facts. Such statements are based upon the current beliefs and expectations of Merck's management and are subject to significant risks and uncertainties. Actual results may differ from those set forth in the forward-looking statements.

The following factors, among others, could cause actual results to differ from those set forth in the forward-looking statements: the possibility that the expected synergies from the merger of Merck and Schering-Plough will not be realized, or will not be realized within the expected time period; the impact of pharmaceutical industry regulation and health care legislation; the risk that the businesses will not be integrated successfully; disruption from the merger making it more difficult to maintain business and operational relationships; Merck's ability to accurately predict future market conditions; dependence on the effectiveness of Merck's patents and other protections for innovative products; the risk of new and changing regulation and health policies in the United States and internationally and the exposure to litigation and/or regulatory actions.

Merck undertakes no obligation to publicly update any forward-looking statement, whether as a result of new information, future events or otherwise. Additional factors that could cause results to differ materially from those described in the forward-looking statements can be found in Merck's 2010 Annual Report on Form 10-K and the company's other filings with the Securities and Exchange Commission (SEC) available at the SEC's Internet site (www.sec.gov).

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A 'Newer' Era of HCV Therapy Begins?

William F. Balistreri, MD

Posted: 12/16/2011

Dawning of Another New Era

In an editorial appearing in the New England Journal of Medicine^[1] in March of this year, Jensen suggested that a new era of therapy for hepatitis C virus (HCV) infection was dawning with the development of 2 effective protease inhibitors -- telaprevir and boceprevir. These direct-acting antiviral (DAA) agents, used in combination with peginterferon and ribavirin, were shown to be effective in patients infected with HCV genotype 1. Now an even newer era may be on the horizon!

New Compounds, New Hope

Several investigational drug trials were presented at The Liver Meeting 2011 -- the annual meeting of the American Association for the Study of Liver Diseases. Two groups reported the apparently remarkable preliminary results of an investigational agent for the treatment of infection with HCV.^[2,3] An interferon-free regimen of PSI-7977 plus ribavirin achieved strikingly high rates of sustained viral response (SVR); this drug offers the potential solution to a long sought after goal -- the ability to delete noisome interferon injections from treatment strategies.

PSI-7977 is a uridine nucleotide analog polymerase inhibitor that is administered orally once daily. This agent has previously demonstrated robust activity in patients infected with HCV genotype 1 when used in combination with pegylated-interferon and ribavirin, and activity when used as a monotherapy has also been reported.

Promising Antiviral Activity

Two phase 2 studies of this investigational compound were presented at The Liver Meeting 2011.

The aim of the first (ELECTRON) trial was to determine the shortest duration of interferon, if any, that was required to achieve SVR when PSI-7977 plus ribavirin are coadministered.^[2] Forty treatment-naive, noncirrhotic patients infected with HCV genotype 2 or 3were randomly assigned to receive PSI-7977 400 mg plus ribavirin for 12 weeks -- this was combined with either no interferon or interferon for 4, 8, or 12 weeks. All patients achieved a rapid virologic response (RVR); > 80% had nondetectable HCV RNA at 2 weeks and all patients had undetectable levels at 3 weeks. All patients achieved an end-of-treatment (ETR) response and normalization of alanine aminotransferase levels. No serious adverse events were attributed to PSI-7977, and as expected, safety and tolerability were highest in the interferon-free treatment group. Buoyed by these results, the investigators carried out a small trial of open-label PSI-7977 monotherapy for 12 weeks; the response rates were similar to the combination therapy results.

A similar study (PROTON), a double-blind, placebo-controlled, dose-ranging study of PSI-7977, enrolled 121 treatment-naive patients with HCV genotype 1.^[3] Patients were randomly assigned to receive either 12 weeks of interferon/ribavirin plus PSI-7977 (200 mg or 400 mg), or placebo. Duration of therapy was response guided. The control group received the interferon/ribavirin standard combination for 48 weeks. The RVR for the 200 mg and the 400 mg dose was 98%, with an ETR at 24 weeks of 91%. The RVR in the placebo group was 19%, and the ETR was 50%. Of specific note, all patients with the difficult-to-treat interleukin 28B single-nucleotide polymorphism T/T mutation had an RVR -- all became HCV-negative by week 3 and 100% went on to achieve an SVR.

The studies suggest that PSI-7977 exhibits high-potency antiviral activity against a broad range of HCV genotypes and has a high barrier to resistance; the agent reduced the duration of therapy for HCV clearance in half. The impact may be significant -- offering a shorter, interferon-free regimen that is effective even in difficult-to-treat patients. A newer era indeed!

The potent antiviral efficacy in association with a promising safety profile, support the continued exploration of PSI-7977 with abbreviated interferon duration, as monotherapy, or with other DAA in patients with all HCV genotypes. These further studies will hopefully confirm this optimism and document the spectrum of potential adverse effects of this drug.

References

1. Jensen DM. A new era of hepatitis C therapy begins. N Engl J Med. 2011;364:1272-1274.
2. Gane EJ, Stedman CA, Hyland RH, et al. Once daily PSI-7977 plus RBV: pegylated interferon-ALFA not required for complete rapid viral response in treatment-naïve patients with HCV GT2 or GT3. Program and abstracts of The Liver Meeting 2011: American Association for the Study of Liver Diseases (AASLD) 62nd Annual Meeting; November 9-13, 2011; Boston, MA. Abstract 34.
3. Lawitz E, Lalezar JP, Hassanein T, et al. Once-daily PSI-7977 plus Peg/RBV in treatment-naïve patients with HCV GT1: robust end of treatment response rates are sustained post-treatment. Program and abstracts of The Liver Meeting 2011: American Association for the Study of Liver Diseases (AASLD) 62nd Annual Meeting; November 9-13, 2011; Boston, MA. Abstract 225.

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