Silverback Therapeutics Announces Presentation of Preclinical Data at ASCO Supporting Potential Clinical Activity of SBT6050 as a Single Agent and in Combination with Trastuzumab for the Treatment of HER2-Expressing Malignancies

Silverback Therapeutics ("Silverback"), a biopharmaceutical company advancing a pipeline of therapies that are systemically delivered, but locally active, today announced that preclinical data for its lead ImmunoTACtm candidate, SBT6050, will be presented at the ASCO Virtual Scientific Program at 8:00 a.m. ET on May 29, 2020.

The presentation, titled "SBT6050, a HER2-Directed TLR8 Therapeutic, is a Systemically Administered, Tumor-Targeted Human Myeloid Cell Agonist," shows that SBT6050 potently activates human myeloid cells in a HER2 dependent manner in vitro, and that an SBT6050 mouse surrogate exhibits potent anti-tumor efficacy as a single agent and in combination with trastuzumab in vivo.

Robust, durable single agent activity is observed with the SBT6050 mouse surrogate in multiple tumor models, including a human xenograft model lacking T, B, and NK cells, demonstrating the potential of myeloid cells to mediate strong anti-tumor activity. In a HER2-positive human xenograft model, a combination of low dose SBT6050 mouse surrogate with trastuzumab greatly enhanced the anti-tumor activity observed with either agent alone. These data demonstrate the potential for clinical activity with SBT6050 as a single agent and in combination with trastuzumab in the setting of moderate or high HER2-expressing malignancies.

"SBT6050 was designed to elicit a broad spectrum of anti-tumor immune responses through localized and potent activation of human myeloid cells," said Valerie Odegard, Ph.D., Silverback's chief scientific officer. "Our preclinical data continue to highlight the potential for single agent clinical activity with SBT6050 even in tumors with diminished or absent T-cell infiltrates, and the opportunity for enhanced activity in combination with trastuzumab. We are encouraged by the preclinical data and plan to initiate clinical investigation of SBT6050 later this year."

About Silverback Therapeuticstm

Silverback Therapeutics is a privately held biopharmaceutical company advancing a pipeline of therapies that are systemically delivered, but locally active and target fundamental disease pathways. Silverback's ImmunoTACtm technology is a targeted therapy platform designed to promote local modulation of important biologic pathways which enables innovative therapeutic approaches for oncology, virology, and fibrosis. Silverback's lead candidate, SBT6050, is a novel immuno-oncology therapeutic comprised of a TLR8 specific agonist (a potent activator of myeloid cells) conjugated to a HER2-directed monoclonal antibody. Solid tumors, including those resistant to T cell targeted immunotherapy, are replete with myeloid cells. Activation and reprogramming of myeloid cells drives an innate immune response resulting in direct tumor killing and can also nucleate a T cell response. Successful activation of myeloid cells can lead to anti-tumor immunity, even in tumors that are resistant to immune checkpoint blockade. Clinical investigation of SBT6050 is expected to begin in 2H 2020. Silverback Therapeutics is located in Seattle, Washington. To learn more, visit www.silverbacktx.com.