Xencor Presents Data from Multiple Preclinical XmAb Bispecific Antibody and Cytokine Programs at the AACR Annual Meeting 2021

Xencor, Inc. (NASDAQ:XNCR), a clinical-stage biopharmaceutical company developing engineered monoclonal antibodies and cytokines for the treatment of cancer and autoimmune diseases, today announced the presentation of new data from multiple preclinical XmAb bispecific antibody programs and its preclinical IL-12-Fc cytokine program at the American Association for Cancer Research (AACR) Annual Meeting, being held virtually April 10-15, 2021.

"Xencor’s XmAb bispecific Fc domains enable the rapid design and simplified development of Fc-containing protein structures and are being used to create new platforms, a wide range of multi-specific antibodies and engineered cytokines. At AACR, we are presenting emerging preclinical data from early-stage programs that highlight the potential of our CD28 platform and XmAb 2+1 bispecific antibody format, as well as our more advanced IL-12 cytokine, which builds off our prior work with IL-15 and IL-2," said John Desjarlais, Ph.D., senior vice president and chief scientific officer at Xencor. "In 2021, we anticipate submitting an IND for XmAb819, our lead XmAb 2+1 CD3 bispecific antibody targeting ENPP3, and initiating a Phase 1 study in early 2022. We are also advancing through preclinical development our wholly owned lead CD28 candidate, a B7-H3 x CD28 bispecific antibody designed to be evaluated for the treatment of patients with a range of solid tumors."

Poster presentations will be archived under "Events & Presentations" in the Investors section of the Company's website located at www.xencor.com.

XmAb Engineered Cytokine Platform

• Abstract 1743, "IL12 heterodimeric Fc-fusions engineered for reduced potency exhibit strong anti-tumor activity and improved therapeutic index compared to native IL12 agents"

IL-12 is a potent proinflammatory cytokine produced by activated antigen-presenting cells, and it leads to proliferation of T cells and NK cells and increased cytotoxicity through high levels of interferon gamma signaling. As a potent immune stimulating protein, IL-12 can have a significant effect on shrinking tumors; however, prior clinical studies have demonstrated it to have a narrow therapeutic window, limiting potential response rates.