20/02/2012 — BERKELEY, Calif. — (BUSINESS WIRE)

Plexxikon Inc., a member of Daiichi Sankyo Group, today announced that
the European Commission has approved Zelboraf® (vemurafenib) for the
monotherapy treatment of adult patients with BRAF^V600
mutation-positive unresectable or metastatic melanoma. The cobas 4800
BRAF V600 Mutation Test, a companion diagnostic used to identify
patients with the BRAF mutation, is CE marked and commercially available
in Europe. Zelboraf is designed to selectively inhibit the BRAF mutation
that occurs in about half of all cases of melanoma.

Zelboraf and its companion diagnostic have already been approved in the
United States, Switzerland, Israel, Brazil, New Zealand and Canada. In
the United States, Zelboraf is being co-promoted by Daiichi Sankyo, Inc.
and Genentech, a member of the Roche Group. Roche promotes Zelboraf
outside of the United States.

“The approval of Zelboraf by the European Commission marks a significant
advancement for European patients with metastatic melanoma who
historically have had very limited treatment options,” said K. Peter
Hirth, Ph.D., chief executive officer of Plexxikon. “We are very pleased
that our strategy to co-develop Zelboraf along with a companion
diagnostic helped accelerate the availability of this personalized
medicine for these patients.”

BRIM3

BRIM3, a global, randomized, open-label, controlled, multicenter, Phase
3 study, compared Zelboraf to dacarbazine (chemotherapy), in 675
patients with previously untreated BRAF^V600E
mutation-positive, unresectable (inoperable) or metastatic melanoma. The
endpoints for BRIM3 were overall survival (OS) and investigator-assessed
progression-free survival (PFS). Other endpoints included confirmed
investigator-assessed overall response rate.

In January 2011, the data safety monitoring board for BRIM3 recommended
termination of the BRIM3 study due to compelling efficacy data, and
further recommended that study patients receiving chemotherapy have the
option to cross over to the vemurafenib treatment arm.

• The pre-specified interim analysis of BRIM3 showed the risk of death
  was reduced by 63 percent for patients who received Zelboraf compared
  to those who received standard first-line treatment (hazard ratio
  [HR]=0.37, p<0.0001).
• In a post-hoc analysis of BRIM3 data with a longer follow up compared
  to previous analyses, including cross-over of patients from the
  chemotherapy treatment arm to the Zelboraf treatment arm, Zelboraf
  significantly improved survival by providing a median overall survival
  of 13.2 months compared to 9.6 months for those who received
  chemotherapy. Historically, patients with metastatic melanoma have had
  a median survival of six to 10 months. This analysis showed the risk
  of death was reduced by 38 percent for patients who received Zelboraf
  compared to those who received chemotherapy (hazard ratio [HR]=0.62,
  p<0.0001).
• At 12 months, 55% of patients who received Zelboraf were alive, as
  compared to 43% of patients who received chemotherapy.

In the single arm BRIM2 study of previously treated patients, Zelboraf
treatment also showed a survival benefit compared to historical control
data. These data are expected to publish shortly.

Marketing authorization submissions for Zelboraf are currently under
review by health authorities in Australia, India, Mexico and other
countries worldwide.

Important Safety Information about Zelboraf (vemurafenib)

This information does not take the place of the patient talking to his
or her doctor about their medical condition or their treatment with
Zelboraf.

Zelboraf is a prescription medicine used to treat a type of skin cancer
called melanoma that has spread to other parts of the body or cannot be
removed by surgery, and has a certain type of abnormal “BRAF” gene.

Zelboraf may cause a type of skin cancer called cutaneous squamous cell
carcinoma (cuSCC), that usually does not spread to other parts of the
body. Patients should check their skin and tell their doctor about skin
changes including a new wart, a skin sore or reddish bump that bleeds or
does not heal, or a mole that changes size or color.

While taking Zelboraf, patients should avoid going out in the sun. When
patients go outside, they should wear clothes that protect their skin,
including head, face, hands, arms and legs. They should use lip balm and
a broad-spectrum UVA/UVB sunscreen with SPF 30 or higher.

Possible serious side effects of Zelboraf include severe allergic
reactions; severe skin reactions; changes in the electrical activity of
the heart called QT prolongation, which can potentially be
life-threatening; abnormal liver function tests; eye problems; or new
melanoma lesions.

Common side effects of Zelboraf include joint pain, rash, hair loss,
tiredness, sunburn or sun sensitivity, nausea, itching or warts.

These are not all of the possible side effects of Zelboraf. Patients
must tell their doctor if they have any side effect that bothers them or
does not go away. For more information about side effects, patients
should ask their doctor or pharmacist.

Patients should call their doctor for medical advice about any side
effects. Patients or their caregivers are encouraged to report negative
side effects of prescription drugs to the FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.
They may also report side effects to Genentech at 1-888-835-2555.

Patients should read the Zelboraf full Prescribing Information and
Medication Guide for additional important safety information at www.zelboraf.com.

About Zelboraf (vemurafenib)

Vemurafenib is a novel, oral small molecule, which was approved by the
FDA in August 2011 and is being marketed in the U.S. as Zelboraf for the
treatment of patients with BRAF^V600E mutation-positive
inoperable or metastatic melanoma as detected by an FDA-approved test.
Zelboraf also has been approved by the European Commission, and in
Switzerland, Israel, Brazil, New Zealand and Canada. Zelboraf is not
recommended for use in melanoma patients who lack the BRAF^V600
mutation. Plexxikon utilized its structure-guided chemistry platform to
discover vemurafenib, and initiated clinical development in 2006.
Shortly thereafter, Plexxikon and Roche signed a collaboration agreement
to co-develop vemurafenib.

The cobas 4800 BRAF V600 Mutation Test, a DNA-based companion diagnostic
used to identify patients whose tumors carry the BRAF mutation, was
simultaneously approved in the U.S., and is CE marked and commercially
available in Europe. Roche Molecular Diagnostics developed the cobas
4800 BRAF V600 Mutation Test following a 2005 agreement with Plexxikon.

Studies of vemurafenib in combination with other approved and
investigational medicines as well as in other tumor types are being
conducted. More information about ongoing vemurafenib studies is
available at www.clinicaltrials.gov
(in the U.S.) or www.clinicaltrialregister.eu
or on the Roche Clinical Trials Registry at www.roche-trials.com
(in the EU). Genentech can also be contacted by calling the company’s
clinical trial call center at 1-888-662-6728 or emailing Genentech@druginfo.com.

About Melanoma and BRAF mutation

Melanoma is the most serious type of skin cancer and is growing at a
rate of about five to six percent annually. More than 75,000 people in
the U.S. and 160,000 people worldwide are diagnosed with melanoma each
year. It is one of the deadliest cancers, with a five-year survival rate
of 15 to 20 percent for people with advanced (Stage IV) melanoma,
according to the American Cancer Society.

Risk factors for melanoma include a positive family history of melanoma,
prior melanoma, multiple clinically atypical moles or dysplastic nevi,
inherited genetic mutations, fair skin and sun exposure. However,
melanoma can occur in any ethnic group and also in areas of the body
without substantial exposure to the sun.

The BRAF gene is a key component of a pathway involved in normal cell
growth and survival. BRAF mutations may lead to uncontrolled cell
growth, and are thought to occur in about half of all cases of melanoma
and eight percent of all solid tumors.

About Plexxikon

Plexxikon, a member of Daiichi Sankyo Group, is a leader in the
structure-guided discovery and development of novel small molecule
pharmaceuticals to treat human disease. The company’s lead drug Zelboraf
(vemurafenib/PLX4032) was approved by the FDA in August 2011, and is
being co-promoted in the U.S. by Daiichi Sankyo Inc. and Genentech. The
company is developing a portfolio of clinical and preclinical stage
compounds to address significant unmet medical needs in oncology, as
well as in several other therapeutic indications. Plexxikon’s
Scaffold-Based Drug Discovery^TM platform integrates multiple
state-of-the-art technologies, including structural screening as a key
component that provides a significant competitive advantage over other
drug discovery approaches.

CONTACT:

Plexxikon Inc.
Kathleen Sereda Glaub, +1-510-647-4009
President
kglaub@plexxikon.com
or
For
Plexxikon
Susan Kinkead, +1-415-751-3611
susan@kinkeadcomm.com
or
Jennifer
Cook Williams, +1-360-668-3701
jennifer@cwcomm.org

KEYWORDS: United States Europe North America California Switzerland

INDUSTRY KEYWORDS: Health Biotechnology Oncology Pharmaceutical

MEDIA:

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