Zymeworks and Daiichi Sankyo Announce Immuno-Oncology Cross-Licensing Agreement and Bi-Specific Antibody Collaboration

Vancouver, Canada, Tokyo, Japan and Parsippany, NJ (September 28, 2016) – Zymeworks Inc., a clinical-stage biopharmaceutical company discovering and developing innovative multi-functional protein-based therapeutics including bi-specific antibodies and drug conjugates for the treatment of cancer, and Daiichi Sankyo Company, Limited (hereafter, Daiichi Sankyo) announced today that they have entered into a cross-licensing and collaboration agreement to develop proprietary cancer immuno-oncology products.

Under the terms of the agreement, Daiichi Sankyo will acquire a license to Zymeworks’ Azymetric™ and Effector Function Enhancement and Control Technology (EFECT™) platforms to develop a bi-specific antibody therapeutic, for which Zymeworks will receive an upfront technology access fee and research support. Zymeworks will also be eligible to receive payments upon the achievement of preclinical, clinical and commercial milestones, as well as up to double-digit tiered royalties on global product sales. Additionally, Zymeworks will license immuno-oncology antibodies from Daiichi Sankyo, with the right to research, develop and commercialize multiple bi-specific products globally in exchange for royalties on product sales. Further financial details are not disclosed.

“We are very excited to enter into this cross-licensing agreement with Daiichi Sankyo,” said Ali Tehrani, Ph.D., President and CEO of Zymeworks. “The in-licensing component of the transaction will enable Zymeworks to expand its therapeutic pipeline in the near term by accelerating a number of our immuno-oncology programs into the clinic and to ultimately provide more effective and targeted treatments to patients. Additionally, we believe that the licensing of Zymeworks’ platforms to Daiichi Sankyo further demonstrates the potential of the Azymetric™ and EFECT™ technologies for the discovery and development of next-generation multi-functional biologics.”

“Targeting two drivers of disease with a single monoclonal antibody is a key scientific advance that may help change the standard of care for patients with cancer,” said Antoine Yver, MD, MSc, Executive Vice President and Global Head, Oncology Research and Development, Daiichi Sankyo. “We are looking forward to strengthening our expertise in bi-specific immuno-oncology by working closely with Zymeworks on this collaboration.”

About the Azymetric™ Platform
Bi-specific antibodies developed using the Azymetric™ platform resemble conventional mono-specific antibodies while being able to simultaneously bind to two different targets resulting in additive or synergistic therapeutic responses. Azymetric™ antibodies spontaneously assemble into a single molecule with two different Fab domains comprising of unique heavy and light chain pairings. Azymetric™ antibodies are manufactured using conventional monoclonal antibody processes and can be easily adapted to rapidly screen target and sequence combinations for bi-specific activity in the final therapeutic format, thereby significantly reducing drug development timelines.

About the EFECT™ Platform
The EFECT™ platform is a library of antibody Fc modifications engineered to modulate the
activity of the antibody-mediated immune response, which includes both the up and downregulation
of effector functions. This platform is compatible with traditional monoclonal and well
as Azymetric™ bi-specific antibodies to further enable the customization of therapeutic responses
for different diseases.

About Zymeworks Inc.
Zymeworks is a privately held clinical-stage biotherapeutics company that is developing best-inclass
Azymetric™ bi-specific antibodies and antibody drug conjugates for the treatment of
cancer, autoimmune and inflammatory diseases. The company’s novel Azymetric™,
AlbuCORE™, and EFECT™ platforms, its Zymelink™ conjugation platform and cytotoxins, and
its proprietary ZymeCAD™ structure-guided protein engineering technology, enable the
development of highly potent bi-specific antibodies, multivalent protein therapeutics, and
antibody drug conjugates across a range of indications. Zymeworks is focused on accelerating its
clinical and preclinical biotherapeutics pipeline through in-house research and development
programs and strategic collaborations. More information on Zymeworks can be found at
www.zymeworks.com.

About Daiichi Sankyo Cancer Enterprise
The vision of Daiichi Sankyo Cancer Enterprise is to push beyond traditional thinking to align
world-class science to create innovative treatments for patients with cancer. The oncology
pipeline of Daiichi Sankyo continues to grow and currently includes more than 20 small
molecules and monoclonal antibodies with novel targets in both solid and hematological cancers.
Compounds in phase 3 development include: quizartinib, an oral FLT3 inhibitor, for newlydiagnosed
and relapsed/refractory FLT3-ITD+ acute myeloid leukemia (AML); pexidartinib, an
oral CSF-1R inhibitor, for tenosynovial giant cell tumor (TGCT), also known as pigmented
villonodular synovitis (PVNS) and giant cell tumor of the tendon sheath (GCT-TS), which also is
being investigated in combination with anti-PD1 immunotherapy, pembrolizumab, in a range of
solid tumors; and tivantinib, an oral MET inhibitor, for second-line treatment of MET-high
hepatocellular carcinoma in partnership with ArQule, Inc.

About Daiichi Sankyo
Daiichi Sankyo Group is dedicated to the creation and supply of innovative pharmaceutical
products to address diversified, unmet medical needs of patients in both mature and emerging
markets. With over 100 years of scientific expertise and a presence in more than 20 countries,
Daiichi Sankyo and its 16,000 employees around the world draw upon a rich legacy of innovation
and a robust pipeline of promising new medicines to help people. In addition to a strong portfolio
of medicines for hypertension and thrombotic disorders, under the Group’s 2025 Vision to
become a “Global Pharma Innovator with Competitive Advantage in Oncology,” Daiichi Sankyo
research and development is primarily focused on bringing forth novel therapies in oncology,
including immuno-oncology, with additional focus on new horizon areas, such as pain
management, neurodegenerative diseases, heart and kidney diseases, and other rare diseases. For
more information, please visit: www.daiichisankyo.com. Daiichi Sankyo, Inc., headquartered in
Parsippany, New Jersey, is a member of the Daiichi Sankyo Group. For more information on
Daiichi Sankyo, Inc., please visit: www.dsi.com.