An all-oral combination phase II study of Simeprevir and Samatasvir (IDX719) for the treatment of hepatitis C virus infection initiated

  · Phase II HELIX-1 trial is first hepatitis C clinical study to commence
through collaboration agreement between Janssen Pharmaceuticals Inc. and Idenix
Pharmaceuticals Inc.
Stockholm, Sweden — Medivir AB (OMX: MVIR) today announced that Idenix
Pharmaceuticals Inc. has initiated a phase II clinical trial, called HELIX-1,
evaluating an all-oral, direct-acting antiviral (DAA) HCV combination regimen of
simeprevir, a once-daily protease inhibitor jointly developed by Medivir and
Janssen R&D Ireland and samatasvir (IDX719), Idenix’s once-daily pan-genotypic
NS5A inhibitor.

“Hepatitis C is a complex disease and there is a need for multiple treatment
options. Future hepatitis C treatment will be interferon free and will consist
of two to three direct acting antivirals (DAAs). We are pleased and looking
forward to having simeprevir evaluated in this two-direct-acting antiviral phase
II study”, said Charlotte Edenius, EVP Development, Medivir AB.

About the HELIX trial
The HELIX-1 trial is a 12-week, randomized, double-blind, parallel group study
evaluating the safety and tolerability of simeprevir and samatasvir in addition
to antiviral activity endpoints, with a target enrollment of 90 treatment-naïve,
non-cirrhotic, genotype 1b or 4 HCV-infected patients.

Patients will be randomized equally across three treatment arms, receiving 50,
100, or 150 mg samatasvir once-daily for 12 weeks in combination with 150mg
simeprevir plus ribavirin.

The HELIX-1 trial is the first study in HCV-infected patients to commence under
a non-exclusive collaboration agreement signed between Janssen and Idenix in
January 2013. A second trial (HELIX-2) of simeprevir, samatasvir and TMC647055,
a once-daily non-nucleoside polymerase inhibitor boosted with low-dose ritonavir
being developed by Janssen, is expected to commence in the second half of 2013.

For more information please contact:
Rein Piir, EVP Corporate Affairs & IR
Mobile: +46 708 537 292

About Simeprevir
Simeprevir is an investigational NS3/4A protease inhibitor jointly developed by
Medivir AB and Janssen R&D Ireland for the treatment of genotype 1 chronic
hepatitis C in adult patients with compensated liver disease, including all
stages of liver fibrosis. Simeprevir works by blocking the protease enzyme that
enables the hepatitis C virus to replicate in host cells.

New drug applications were recently submitted for simeprevir in Japan and the
United States for the treatment of genotype 1 hepatitis C, and a Marketing
Authorisation Application was submitted to the European Medicines Agency seeking
approval of simeprevir for the treatment of genotype 1 or genotype 4 chronic
hepatitis C. The U.S. FDA has granted Priority Review to the New Drug
Application.

Global phase III studies of simeprevir include PROMISE in adult patients who
have relapsed after prior interferon-based treatment, QUEST-1 and QUEST-2 in
treatment-naïve adult patients, and ATTAIN in prior null-responder adult
patients. In parallel to these trials, phase III studies for simeprevir are
ongoing in treatment-naïve and treatment-experienced HIV-HCV co-infected
patients and HCV genotype 4 patients.

Simeprevir is also being studied in phase II interferon-free trials with and
without ribavirin in combination with:

  · Janssen’s non-nucleoside inhibitor TMC647055 and ritonavir in treatment
-naïve genotype 1a and 1b HCV patients;
  · Gilead Sciences, Inc.’s nucleotide inhibitor sofosbuvir (GS-7977) in
treatment-naïve and previous null-responder genotype 1 HCV patients; and
  · Bristol-Myers Squibb's NS5A replication complex inhibitor daclatasvir in
treatment-naive and previous null-responder genotype 1 HCV patients.

In addition, Janssen Pharmaceuticals, Inc. has entered into a non-exclusive
collaboration with Vertex Pharmaceuticals to evaluate in a phase II study the
safety and efficacy of an all-oral regimen of simeprevir and Vertex’s
investigational nucleotide analogue polymerase inhibitor VX-135 for the
treatment of HCV. As a first step, Janssen Pharmaceuticals, Inc. is conducting a
drug-drug interaction (DDI) study with simeprevir and VX-135.

For additional information about simeprevir clinical trials, please visit
www.clinicaltrials.gov

About Samatasvir (IDX719)
Samatasvir is an NS5A inhibitor with low picomolar, pan-genotypic antiviral
activity in vitro. To date, samatasvir has been safe and well-tolerated after
single and multiple doses of up to 150 mg in healthy volunteers for up to 14
days duration and up to 100 mg in HCV-infected patients for up to 3 days
duration.

There have been no treatment-emergent serious adverse events reported in the
program. Samatasvir has demonstrated potent pan-genotypic antiviral activity in
HCV-infected patients with mean maximal viral load reductions up to
approximately 4.0 log10 IU/mL across HCV genotypes 1-4 in a proof-of-concept,
three-day monotherapy study. For information about Idenix, please refer to
www.idenix.com.

About Hepatitis C
Hepatitis C, a blood-borne infectious disease of the liver and a leading cause
of chronic liver disease and liver transplants, is a rapidly evolving treatment
area with a clear need for innovative treatments. Approximately 150 million
people are infected with hepatitis C virus worldwide, and about 350,000 people
per year die from the disease. When left untreated, hepatitis C can cause
significant damage to the liver including cirrhosis. Additionally, hepatitis C
may increase the risk of developing complications from cirrhosis, which may
include liver failure.

About Medivir
Medivir is an emerging research-based pharmaceutical company focused on
infectious diseases.

Medivir has world class expertise in polymerase and protease drug targets and
drug development which has resulted in a strong infectious disease R&D
portfolio. The Company’s key pipeline asset is simeprevir, a novel protease
inhibitor in late phase III clinical development for hepatitis C that is being
developed in collaboration with Janssen R&D Ireland. Medivir has also a broad
product portfolio with prescription pharmaceuticals in the Nordics.

For more information about Medivir AB, please visit the Company’s website:
www.medivir.com