Xencor, Inc. announced the presentation of results from its Phase 1a single-ascending dose study of XmAb(R) 564 in healthy volunteers. XmAb564 is a potency-tuned IL-2-Fc fusion protein, engineered to selectively activate and expand regulatory T cells (Tregs) for the potential treatment of patients with autoimmune diseases. Results will be presented in a poster titled "XmAb564, a Novel Potency-Tuned IL-2 Fc-usion Protein Selectively Expands Regulatory T Cells: Results from a Single Ascending-Dose Study in Healthy Adult volunteers" at the European Congress of Rheumatology (EULAR) being held May 31 to June 3 in Milan, Italy.

About XmAb®564 (IL-2 Fc): XmAb®564 is a wholly owned, monovalent, potency-tuned IL-2-Fc fusion protein, engineered to selectively activate and expand Tregs for the potential treatment of patients with autoimmune diseases. XmAb564 is engineered with reduced binding affinity for IL-2's beta receptor (IL-2Rß, CD122) and increased binding affinity for its alpha receptor (IL-2Ra, CD25). Xencor's XmAb Bispecific Fc Domain additionally provides a stable protein scaffold and improves XmAb564's pharmacologic properties, and Xencor's Xtend™ Fc technology enhances its circulating half-life.

As presented in November 2022, the Phase 1a study of XmAb564 demonstrated that a single dose of XmAb564 in healthy volunteers was well-tolerated, promoted the selective and sustained expansion of Tregs and exhibited a favorable pharmacokinetic profile. Xencor is conducting a randomized, double-blind, placebo-controlled, multiple-ascending dose Phase 1b clinical study to evaluate the safety and tolerability of XmAb564, administered subcutaneously in patients with atopic dermatitis and psoriasis.