Takeda to Acquire IDM Pharma, Adding MEPACT(R) (Mifamurtide), the First Treatment...

Takeda to Acquire IDM Pharma, Adding MEPACT(R) (Mifamurtide), the First
Treatment Approved for Osteosarcoma in More Than 20 Years, to Its Oncology
Franchise

OSAKA, Japan, and IRVINE, Calif., May 18 /PRNewswire-FirstCall/ -- Takeda
Pharmaceutical Company Limited (TSE: 4502) and IDM Pharma, Inc. (Nasdaq: IDMI)
today announced that Takeda America Holdings, Inc., a wholly-owned subsidiary
of Takeda (Takeda America), and IDM Pharma have entered into an agreement for
Takeda America to acquire IDM Pharma. Takeda America has established Jade
Subsidiary Corporation as a wholly-owned subsidiary to effect that
transaction. Under the agreement, Takeda America will purchase all of IDM
Pharma's outstanding shares for US$2.64 per share in an all cash tender offer
followed by a merger.

Millennium: The Takeda Oncology Company, Takeda's business unit responsible
for global oncology strategy and development, will have global development
responsibility for MEPACT(R), IDM Pharma's primary asset, and Takeda
Pharmaceuticals Europe Ltd. will be responsible for commercializing MEPACT in
Europe.

IDM Pharma received European marketing approval for MEPACT (mifamurtide), a
therapy indicated for the treatment of non-metastatic osteosarcoma (malignant
bone cancer) following surgical removal of the tumor (resection) in children,
adolescents and young adults. Osteosarcoma is a rare and often fatal disease,
with approximately 1,200 new cases diagnosed in Europe each year. The disease
affects primarily children and young adults. The European Commission formally
granted a centralized marketing authorization for MEPACT on March 6, 2009,
allowing it to be marketed in the 27 EU member states, as well as in Iceland,
Liechtenstein and Norway.

"MEPACT delivers a demonstrated survival advantage for young patients with a
specific type of bone cancer and provides Takeda with an approved therapy that
contributes immediately to our top-line growth," said Erich Brunn, CEO of
Takeda Pharmaceuticals Europe Limited, Takeda's wholly-owned UK-based
subsidiary for overseeing pan-European sales and marketing. "We envisage that
the product will become a key driver in enhancing our European oncology
franchise."

"The European approval of MEPACT was the result of decades of research and
most importantly the dedication of patients and their families whose
involvement in the Phase 3 clinical trial was integral to providing access to
the first new osteosarcoma treatment in more than 20 years," added Timothy P.
Walbert, president and chief executive officer IDM Pharma. "Our goal has been
to improve the lives of cancer patients by developing therapies that meet
significant unmet treatment needs - Takeda shares this goal. We expect that
the significant progress we've made with MEPACT during the last two years will
continue to be met in osteosarcoma and other difficult to treat cancers."

About MEPACT
The Phase 3 MEPACT trial was the largest study ever completed in osteosarcoma,
enrolling approximately 800 patients. The study evaluated patient outcomes
with the addition of MEPACT to three- or four-drug adjuvant chemotherapy
(cisplatin, doxorubicin, and methotrexate with or without ifosfamide). Results
demonstrated that the addition of MEPACT to chemotherapy resulted in
approximately a 30 percent decrease in the risk of death with 78 percent of
patients surviving after six years of follow-up after treatment with MEPACT.
MEPACT was well tolerated.

MEPACT was granted orphan medicinal product status in Europe in 2004 and under
European pharmaceutical legislation is entitled to a period of 10 years market
exclusivity in respect of the approved indication.

MEPACT Important Safety Information
Safety of MEPACT has been assessed in studies of patients 2 to 30 years of age
at initial diagnosis of osteosarcoma. The most common side effects were
anemia, anorexia, headache, dizziness, tachycardia, hypertension, hypotension,
dyspnea, tachypnea, cough, vomiting, diarrhea, constipation, abdominal pain,
nausea, hyperhidrosis, myalgia, arthralgia, back pain, pain in extremity,
fever, chills, fatigue, hypothermia, pain, malaise, asthenia, and chest pain.

A pharmacovigilance plan for MEPACT, as for all medicinal products, will be
implemented as part of the marketing authorization.

Detailed recommendations for the use of MEPACT are described in the Summary of
Product Characteristics (SPC) which is published in the European Public
Assessment Report (EPAR) and is available in all official European Union
languages.

About IDM Pharma
IDM Pharma is focused on the development of innovative cancer products that
either destroy cancer cells by activating the immune system or prevent tumor
recurrence by triggering a specific adaptive immune response. IDM Pharma is
dedicated to maximizing the full therapeutic and commercial potential of its
innovative products to address the needs of patients and the physicians who
treat these patients. For more information about the company and its products,
visit www.idm-pharma.com.

About Takeda Pharmaceutical Company Limited
Located in Osaka, Japan, Takeda is a research-based global company with its
main focus on pharmaceuticals. As the largest pharmaceutical company in Japan
and one of the global leaders of the industry, Takeda is committed to striving
toward better health for individuals and progress in medicine by developing
superior pharmaceutical products. Additional information about Takeda is
available through its corporate website, www.takeda.com.

Transaction Information
This transaction is structured as an all cash tender offer for all of the
outstanding shares of IDM Pharma common stock, followed by a merger in which
remaining shares of IDM Pharma not tendered into the offer would be converted
into the right to receive the same US$2.64 cash per share price paid in the
tender offer. The transaction has been unanimously approved by the Boards of
Directors of IDM Pharma and Takeda. In connection with signing of the merger
agreement, stockholders holding shares representing approximately 55% of the
outstanding IDM Pharma common stock (49% of the common stock on a fully
diluted basis including shares issuable upon the exercise of options and
warrants) entered into a stockholders' agreement with Takeda America that
commits the stockholders to tender their shares in the tender offer, subject
to certain conditions. The transaction is subject to the tender of a majority
of IDM Pharma common stock on a fully diluted basis as well as other customary
closing conditions. The transaction is expected to be completed in June 2009
and no later than 22 July 2009. JMP Securities LLC is acting as financial
advisor and Cooley Godward Kronish LLP is serving as legal counsel to IDM
Pharma in the transaction. WilmerHale is serving as legal counsel to Takeda
America in the transaction.

Forward-Looking Statements
This press release includes forward-looking statements that are subject to
risks, uncertainties and other factors, including the risks to both companies
that the acquisition of IDM Pharma will not be consummated as the transaction
is subject to certain closing conditions. All statements other than statements
of historical fact are statements that could be deemed forward-looking
statements, including statements regarding the anticipated timing of
completion of the transaction; the ability to complete the transaction
considering the various closing conditions; any projections of earnings,
revenues or other financial items; any estimates or projections of the patient
population for MEPACT; any statements regarding the future of MEPACT; any
statements of the plans, strategies and objectives of management for future
operations; any statements of expectation or belief; and any statements of
assumptions underlying any of the foregoing. In addition, if and when the
transaction is consummated, there will be risks and uncertainties related to
Takeda's ability to successfully incorporate IDM Pharma's assets into its
business operations, the ability to complete post-approval development
commitments for MEPACT and the contribution of MEPACT to Takeda's European
oncology franchise. These and other risks and uncertainties are discussed in
documents filed with the U.S. Securities and Exchange Commission by IDM
Pharma, and will be discussed in the tender offer documents to be filed by
Takeda or its affiliate and the Solicitation/Recommendation Statement to be
filed by IDM Pharma. All forward-looking statements are based on information
currently available to Takeda and IDM Pharma, and neither Takeda nor IDM
Pharma assumes any obligation to update any such forward-looking statements or
other statements included in this press release.

Important Additional Information Will Be Filed with the Securities Exchange
Commission (SEC)
This press release is neither an offer to purchase nor a solicitation of an
offer to sell shares of IDM Pharma, Inc. Takeda America has not commenced the
tender offer for shares of IDM Pharma stock described in this press release.

At the time the tender offer is commenced, Takeda America and one of its
affiliates will file with the SEC a Tender Offer Statement on Schedule TO and
related exhibits, including an Offer to Purchase, Letter of Transmittal and
other related documents, and IDM Pharma will file with the SEC a Tender Offer
Solicitation/Recommendation Statement on Schedule 14D-9 in connection with the
transaction. These will contain important information about Takeda, Takeda
America and IDM Pharma, the transaction and other related matters. Investors
and security holders are urged to read each of these documents carefully when
they are available. The tender offer materials (including the Offer to
Purchase, the related Letter of Transmittal and certain other offer documents)
and the Solicitation/Recommendation Statement will contain important
information, which should be read carefully before any decision is made with
respect to the tender offer. The Offer to Purchase, the related Letter of
Transmittal and certain other offer documents, as well as the
Solicitation/Recommendation Statement, will be made available to all
stockholders of IDM Pharma at no expense to them. These materials will be sent
free of charge to all stockholders of IDM Pharma. In addition, all of these
materials (and all other materials filed by IDM Pharma with the SEC) will be
available at no charge from the SEC through its website at www.sec.gov.
Investors and security holders may also obtain free copies of the documents
filed with the SEC by Takeda America at www.idm-pharma.com.

SOURCE Takeda Pharmaceutical Company Limited; IDM Pharma, Inc.

Seizo Masuda, Public and Investor Relations of Takeda Pharmaceutical Company
Limited, +81 3 3278 2037, masuda_seizo@takeda.co.jp; or Robert J. De Vaere,
Sr. Vice President & CFO of IDM Pharma, +1-949-470-6447,
bdevaere@idm-pharma.com; or Manisha Pai, Corporate Communications of
Millennium: The Takeda Oncology Company, +1-617-551-7877, Manisha.Pai@mpi.com;
or Richard Kenyon, Corporate Communications of Takeda Pharmaceuticals Europe
Limited, +44 20 3116 8861, richard.kenyon@tpeu.co.uk