Success Fee Paid to AnaptysBio as Milestone Under Partnership

SAN DIEGO, CA, USA | September 1, 2011 | AnaptysBio, Inc., a privately-held therapeutic antibody company, today announced the successful completion of a therapeutic antibody generation project with a leading global pharmaceutical company. This is the second successful completion of a pharma project announced by AnaptysBio in 2011.

“Recent advances in the SHM-XELTM platform permitted AnaptysBio to achieve this milestone in a rapid timeframe, and generate numerous antibodies surpassing the design goals required by our pharma partner.”

“Our SHM-XELTM platform continues to deliver high-affinity therapeutic antibodies to a variety of therapeutic targets,” said James Topper, executive chairman of AnaptysBio. “Recent advances in the SHM-XELTM platform permitted AnaptysBio to achieve this milestone in a rapid timeframe, and generate numerous antibodies surpassing the design goals required by our pharma partner.”

Under the terms of the partnership, the pharma partner has received worldwide rights to the development and commercialization of three antibodies generated by AnaptysBio using the SHM-XEL platform. In addition to upfront and success fees already received, AnaptysBio is eligible to receive milestone payments and royalties upon development and sale of any products derived from the partnership.

About AnaptysBio

Founded in 2005, AnaptysBio, Inc. is a privately-held company focused on the generation of antibody therapeutics, and the leader in the use of somatic hypermutation (SHM) for antibody discovery and optimization. SHM is the body’s natural process for generating potent antibodies. The Company’s SHM-XEL™ platform couples SHM with mammalian cell display to generate antibodies for therapeutic applications through an iterative process of natural evolution and high-throughput selection under controlled conditions – a process that has been referred to as “naturalizing” antibodies. This versatile platform can be used for both discovery of new antibodies and optimization of existing antibodies to generate candidates with desired properties for therapeutic applications. AnaptysBio has established broad intellectual property around the use of SHM, and is currently building a pipeline of novel therapeutic antibody product candidates. Major investors in AnaptysBio include founding investor Avalon Ventures, as well as Alloy Ventures, Frazier Healthcare Ventures, and Novo A/S. For more information, visit www.anaptysbio.com.

SOURCE: AnaptysBio, Inc.