Phase II all-oral combination studies of Simeprevir, TMC647055 and IDX719 for the treatment of Hepatitis C to be initiated shortly

Stockholm, Sweden — Medivir AB (OMX: MVIR) today announced a non-exclusive
collaboration between Janssen Pharmaceuticals Inc. (Janssen) and Idenix
Pharmaceuticals for the clinical development of an all-oral (interferon-free)
direct-acting antiviral (DAA) hepatitis C (HCV) combination therapy. The
collaboration will evaluate combinations including simeprevir (TMC435), a once
-daily protease inhibitor jointly developed by Janssen R&D Ireland and Medivir,
TMC647055, a potent once-daily NNI (non-nucleoside inhibitor) of the HCV
polymerase, boosted with low dose ritonavir, being developed by Janssen and
IDX719, Idenix’s once-daily pan-genotypic NS5A inhibitor.

Clinical development plans include an initial drug-drug interaction study to
begin in the first quarter of 2013, followed by phase II studies as agreed
between the companies, and pending approval from regulatory authorities. The
phase II program is expected to first evaluate the two-DAA combination of IDX719
and simeprevir plus ribavirin for 12 weeks in treatment-naïve HCV-infected
patients. Subsequently, the companies plan to evaluate a three-DAA combination
of IDX719, simeprevir, TMC647055/r, with or without ribavirin. The clinical
trials will be conducted by Idenix. Both companies retain all rights to their
respective compounds under this agreement.

”This collaboration agreement underscores our strong commitment to develop
interferon-free treatment options with simeprevir as a base for hepatitis C
patients”, says Charlotte Edenius, EVP of Research and Development, Medivir AB.
“We are committed to develop these new treatments, where already four different
interferon-free combinations with simeprevir are under investigation, with the
potential to achieve high viral cure rates after only 12 weeks of total
treatment, and we look forward to start this new collaboration with Idenix.”

For more information please contact:
Rein Piir, EVP Corporate Affairs & IR
Direct: +46 8 440 6550 or: Mobile: +46 708 537 292.

About Simeprevir (TMC435)
Simeprevir is a once-daily potent investigational hepatitis C protease inhibitor
in late phase III clinical development being jointly developed by Janssen R&D
Ireland and Medivir AB to treat chronic hepatitis C virus infections. Simeprevir
is being investigated in combination with PegIFN/RBV in phase III trials and is
also being evaluated with Direct-acting Antiviral (DAA) agents in four other
phase II interferon-free combinations both with and without ribavirin (RBV).

Global phase III studies of simeprevir in combination with PegIFN/RBV include
the following studies:

  · QUEST-1 and QUEST-2 in treatment-naïve patients.
  · PROMISE in patients who have relapsed after prior interferon-based
treatment.
  · ATTAIN in prior null-responder patients and studies in Japanese HCV genotype
1 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 in
HCV genotype 4 patients.

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

  · Simeprevir in combination with Gilead Sciences’ sofosbuvir (GS7977) in
hepatitis C genotype 1 treatment-naïve or prior null responder patients.
  · Simeprevir in combination with BMS’s, daclatasvir in hepatitis C genotype 1
treatment-naïve or prior null responder patients.
  · Simeprevir in combination with Janssen’s TMC647055 and low dose ritonavir in
hepatitis C genotype 1 treatment-naïve, prior relapser or null responder
patients.
  · Simeprevir in combination with Vertex’s VX-135 in hepatitis C genotype 1
treatment-naïve patients to commence in 2013.

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

About IDX719
IDX719 is an NS5A inhibitor with low picomolar, pan-genotypic antiviral activity
in vitro. To date, IDX719 has been safe and well tolerated after single and
multiple doses of up to 100 mg in healthy volunteers (n=36; up to 7 days
duration) and HCV-infected patients (n=69; up to 3 days duration). There have
been no treatment-emergent serious adverse events reported in the program.
IDX719 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 more information about IDX719, please visit www.idenix.com.

About TMC647055
TMC647055 is a potent non-nucleoside hepatitis C polymerase inhibitor with broad
genotypic coverage. TMC647055 is in phase II clinical development and is
developed by Janssen R&D Ireland to treat chronic hepatitis C virus infections.
TMC647055 is being investigated in combination with other DAA agents in all oral
interferon-free regimens. There have been no treatment-emergent serious adverse
events reported in the program.

About Hepatitis C
Hepatitis C is a blood-borne infectious disease of the liver and is a leading
cause of chronic liver disease and liver transplants. The World Health
Organization estimates that nearly 170 million people worldwide, approximately
3% of the world's population, are infected with hepatitis C virus (HCV). The CDC
(Centers for Disease Control and Prevention) has reported that more than three
million people in the United States are chronically infected with HCV.

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 (TMC435),
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, please visit the Company’s website:
www.medivir.com