Stylli brings record of success in drug development and technology commercialization

PDL licenses Xencor XmAb™ technology to enhance antibody activity

Discovery Enables Dominant Negative Inhibitor Strategy and Clarifies BAFF Structural Controversy

Protein Design Automation platform enables Medicinal Chemistry for Proteins™

Genentech licenses Xencor’s XmAb™ technology for CD20 and Her2, key cancer and autoimmune targets

Xencor and Chugai Initiate Partnership for Optimized Antibodies Chugai licenses Xencor’s XmAb™ technology to enhance antibody efficacy Monrovia, CA – January 10, 2005 – Xencor today announced a license and collaboration agreement with Chugai Pharmaceutical Co., Ltd.

Xencor Licenses Protein Variants to Lilly Monrovia, CA – April 13, 2005 – Xencor today announced that Eli Lilly and Company has exercised its option to develop one or more therapeutic proteins created by Xencor under its collaboration with Lilly. Xencor used its proprietary Protein Design

FierceBiotech Honors Xencor as One of the MONROVIA, CA – June 21, 2005 – Xencor, Inc., a company engineering superior biotherapeutics using its Protein Design Automation® technology, announced today that it has been selected as one of the “Fierce 15“ for 2005 by FierceBiotech, an internationally

Xencor, Inc. Signs Collaboration with Centocor, Inc. to Improve Antibodies Xencor, Inc. licenses engineered Fc domains to Centocor, Inc. to enhance therapeutic efficacy Monrovia, CA – July 18, 2005 – Xencor, Inc., a biotherapeutics company developing protein therapeutics and antibody drugs, today

Xencor Gives Panel Presentation and Company Update at BIO InvestorForum; Announces Recent Close of $20 Million in Financing MONROVIA, CA – October 18, 2005 – Xencor, Inc., a biotherapeutics company developing protein therapeutics and antibody drugs, announced today that Bassil Dahiyat, Ph.D.,