Theraclone Sciences Secures $10.6 Million in Series B Extension Financing

Seattle, WA - September 9, 2011 - Theraclone Sciences, Inc., a therapeutic antibody discovery and
development company, today announced a $10.6 million extension to its Series B financing, bringing
the total round to $41 million. Previous investors ARCH Venture Partners, Canaan Partners, MPM
Capital, Healthcare Ventures, Alexandria Real Estate Equities, Amgen Ventures and Zenyaku Kogyo
participated in the financing. Proceeds will help advance Theraclone's clinical programs and support
ongoing discovery projects using Theraclone's I-STARTM technology platform, which is designed for the
rapid screening and identification of rare, potent and therapeutically-relevant human antibodies.

"The anticipated near-term initiation of Theraclone's first clinical trial and our discovery collaboration
with Pfizer earlier this year are important milestones that demonstrate Theraclone's continued progress
with our R&D pipeline and technology platform. The continued support from our investors represents
both a vote of confidence and an ability to sustain our rapid pace of activity and progress," said Steven
Gillis, Ph.D., Executive Chairman and acting CEO of Theraclone.

About Theraclone Sciences
Theraclone Sciences is a Seattle-based biotechnology company focused on the development of novel
therapeutic antibodies for the treatment of infectious disease and cancer. The company's technology
harnesses the power of the human immune system to identify rare, naturally evolved antibodies from
the blood cells of immunologically relevant human subjects. Human monoclonal antibodies can be
rapidly isolated using the I-STARTM discovery platform and scaled for industrial production. Such human
antibody drug candidates may be uniquely safe and relevant to combating disease across broad patient
populations. Theraclone is a privately held company with venture investment from ARCH Venture
Partners, Canaan Partners, Healthcare Ventures, MPM Capital, Amgen Ventures and Alexandria Real
Estate Equities. For additional