Atreca, Inc. and Xencor, Inc. announced, as part of their existing strategic collaboration, they have mutually selected the first program combining an Atreca-discovered antibody with Xencor's XmAb® bispecific Fc domain and a cytotoxic T-cell binding domain (CD3). Under the terms of their 2020 collaboration, Atreca generates novel, tumor-binding antibodies from the immune responses of cancer patients and identifies the antibodies' targets. Xencor then engineers Atreca's antibodies into T-cell engaging bispecific antibodies that bind to and activate the CD3 co-receptor on T cells, and characterizes these novel XmAb bispecific antibodies to identify candidates for further development.

The program announced is the first of up to two joint programs that can be mutually selected for further development and commercialization, with each partner sharing 50% of costs and profits. Atreca will lead clinical development, regulatory and commercialization activities for this program, and the second potential joint program would be advanced by Xencor. In addition, the agreement allows for each partner to pursue up to two programs arising out of the collaboration independently.

The joint program announced is based on APN-346958, an Atreca-discovered antibody. APN-346958 targets a novel RNA-binding protein and is tumor-reactive in at least 50% of samples for six tumor types evaluated, including: colorectal, thyroid, head and neck, urothelial, melanoma and brain cancer. In preclinical studies, the XmAb bispecific antibodies engineered against APN-346958's target have demonstrated potent anti-tumor activity.

Atreca and Xencor expect to name a candidate from the program later this year, and Atreca targets an investigational new drug (IND) submission by early 2025.