Atreca and Xencor to Develop T Cell Engaging Bispecific Antibody Directed Against Novel Solid Tumor Target

Atreca, Inc., a clinical-stage biotechnology company focused on developing novel therapeutics generated through a unique discovery platform based on interrogation of the active human immune response, and Xencor, Inc., a clinical-stage biopharmaceutical company developing engineered antibodies and cytokines for the treatment of cancer and autoimmune diseases, 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 today 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 today 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.

“The advancement of this program into joint development is a key milestone in our collaboration with Xencor,” said Stephen Gould, Ph.D., Chief Scientific Officer of Atreca. “We continue to believe that our respective approaches have the potential to be highly complementary, given the abundance of novel antibody-target pairs generated by Atreca’s discovery platform and the plug-and-play nature of Xencor’s XmAb bispecific antibody platform. We are excited to continue working with Xencor to advance this program and generate additional programs combining Atreca antibodies and Xencor CD3 bispecific engineering.”

“We are using our modular protein engineering platforms to create a new generation of XmAb bispecific antibodies that can act directly and selectively against solid tumors with cytotoxic T cell engagement,” said John Desjarlais, Ph.D., Senior Vice President and Chief Scientific Officer at Xencor. “Today’s announcement speaks to the productivity of our ongoing collaboration with Atreca, and we look forward to evaluating additional molecules engineered with antibodies presented by Atreca’s unique and differentiated discovery platform.”