Tallac Therapeutics Announces FDA Clearance of Investigational New Drug (IND) Application for TAC-001, a First-in-Class Toll-like Receptor 9 (TLR9) Agonist Antibody Conjugate for Patients with Advanced Solid Tumors

Tallac Therapeutics, Inc., a privately held biopharmaceutical company harnessing the power of innate and adaptive immunity to fight cancer, today announced the U.S. Food and Drug Administration (FDA) has cleared an Investigational New Drug (IND) Application to study TAC-001 in a Phase 1/2 clinical trial for patients with advanced or metastatic solid tumors. TAC-001 is the company's lead clinical candidate from its novel Toll-like Receptor Agonist Antibody Conjugate (TRAAC) platform.

"We are delighted that our IND for TAC-001 was cleared by FDA," said Dr. Hong I. Wan, president, CEO and co-founder of Tallac Therapeutics. "TAC-001 is a novel antibody-oligonucleotide conjugate designed to deliver systemic TLR9 agonism with targeted immune activation of B cells, which plays a key role in cancer immunity. In preclinical studies, systemically administered TAC-001 is active as a single agent across a number of syngeneic tumor models including ones with immune suppression and resistance, leading to complete tumor eradication and immune memory. We believe this is a major advancement over the clinically validated intratumorally administered TLR9 agonists and we look forward to advancing TAC-001 into clinical development for cancer patients."

Toll-like receptor 9 (TLR9) agonists are a class of immunotherapy that generate both innate and adaptive immune response which may produce more robust and durable anti-cancer immunity to help overcome resistance to standard-of-care oncology treatments. TLR9 agonists have demonstrated clinical activity in melanoma patients when administered intratumorally. B cells express TLR9 and play pivotal roles in the immune system, and represent a major component of the tumor microenvironment, where they are predominantly associated with tertiary lymphoid structure (TLS). The presence of B cells and TLS is a positive prognostic factor and predicts treatment response to checkpoint inhibitors in multiple solid tumor types.

Tallac Therapeutic's TRAAC platform is designed to deliver a potent and differentiated TLR9 agonist (T-CpG) for targeted immune activation via systemic administration. TAC-001 is comprised of T-CpG conjugated to an antibody against CD22, a receptor restricted to B cells, including tumor-infiltrating B cells. Preclinical studies demonstrate that the innate and adaptive immune responses triggered by TAC-001 leads to robust, curative, and durable single agent anti-tumor activity in checkpoint inhibitor resistant and refractory tumor models. Increased B cell infiltration, T cell effector functions and modulation of suppressive myeloid cells within the tumor microenvironment was observed following systemic TAC-001 administration. These results support the development of TAC-001 for a broad range of solid tumor malignancies, particularly in the tumor types with B cell/TLS involvement.

About TAC-001

TAC-001 is a Toll-like Receptor Agonist Antibody Conjugate (TRAAC) comprised of a potent Toll-like Receptor 9 agonist (T-CpG) conjugated to an antibody against CD22, a receptor restricted to B cells, including tumor-infiltrating B cells. TAC-001 is designed to systemically deliver T-CpG to B cells by binding to CD22, leading to internalization of TAC-001, TLR9 signaling, B cell activation and a cascade of immune reactions. Preclinical studies demonstrate that the innate and adaptive immune responses triggered by TAC-001 leads to potent anti-tumor activity. TAC-001 is being developed for the potential treatment of solid tumors.

About Tallac Therapeutics, Inc.

Tallac Therapeutics is a privately held biopharmaceutical company harnessing the power of innate and adaptive immunity to fight cancer. Tallac's pipeline of immunotherapy candidates are derived from the company's novel Toll-like Receptor Agonist Antibody Conjugate (TRAAC) platform to deliver a potent Toll-like receptor (TLR9) agonist (T-CpG) for targeted immune activation via systemic administration. Several TRAAC molecules are in various stages of discovery and preclinical development. For more information, please visit www.tallactherapeutics.com.