Silverback Therapeutics to Present SBT6290 Preclinical Data at the AACR 2021 Annual Conference

SBT6290 Shown to Activate Myeloid Cells and Drive Anti-tumor Effects in Nectin4-expressing Solid Tumors

Silverback Therapeutics, Inc. SBTX ("Silverback"), a clinical-stage biopharmaceutical company leveraging its proprietary ImmunoTAC technology platform to develop systemically delivered, tissue-targeted therapeutics for the treatment of cancer, chronic viral infections and other serious diseases, will present preclinical data on its second product candidate, SBT6290, at the American Association of Cancer Research (AACR) 2021 Annual Conference, taking place virtually April 10-15. The data highlight the ability of SBT6290, a systemically administered Nectin4-directed TLR8 ImmunoTAC product candidate, to selectively activate myeloid cells in the tumor microenvironment, a promising approach to overcome resistance mechanisms associated with most current immunotherapies.

"SBT6290 showcases the versatility of our ImmunoTAC platform and along with our lead program SBT6050, exemplifies our goal to target difficult-to-treat solid tumors subset by subset. We are building on learnings from SBT6050, leveraging the same TLR8 linker-payload, which is highly transferrable across different targeting antibodies," said Valerie Odegard, Ph.D., president & chief scientific officer of Silverback Therapeutics. "These preclinical data show that SBT6290 activates human myeloid cells in a Nectin4-dependent manner and that a SBT6290 mouse surrogate confers single agent anti-tumor activity in preclinical studies. We will continue to evaluate SBT6290 in GLP toxicology studies and anticipate submitting an IND for this program in the fourth quarter of 2021."

SBT6290 comprises a selective TLR8 agonist conjugated to a Nectin4-specific monoclonal antibody. Nectin4 is a cell surface adhesion molecule that is overexpressed in multiple solid tumor types including urothelial, triple negative breast, squamous cell head and neck, and non-small cell lung cancers, with limited expression in normal tissues.

The abstract is now available on the AACR Annual Meeting website. Details of the poster presentation are as follows:

Title: SBT6290, a Systemically Administered Nectin4-Directed TLR8 ImmunoTAC^® Product Candidate, is Designed for Tumor-localized Activation of Myeloid Cells

Abstract Number: 1858

Session Category: Immunology

Session Title: Therapeutic Antibodies, Including Engineered Antibodies

Virtual Poster Session Date and Time: The poster will be made available on the AACR website and Silverback website on April 10, 2021 at 8:30 a.m. ET

About Silverback Therapeutics

Silverback Therapeutics, Inc. is a clinical-stage biopharmaceutical company focused on leveraging its proprietary ImmunoTAC technology platform to develop systemically delivered and tissue targeted therapeutics for the treatment of cancer, chronic viral infections, and other serious diseases. Silverback's platform enables the strategic pairing of proprietary payloads that modulate key disease modifying pathways with monoclonal antibodies directed at specific disease sites. Initially, Silverback is creating a new class of targeted immuno-oncology agents that direct a TLR8 agonist myeloid cell activator to the tumor microenvironment in solid tumors to promote cancer cell killing. Silverback Therapeutics is located in Seattle, Washington. To learn more, visit www.silverbacktx.com or follow us on LinkedIn.

Forward-Looking Statements

This news release contains certain forward-looking statements that involve risks and uncertainties that could cause actual results to be materially different from historical results or from any future results expressed or implied by such forward-looking statements. Such forward-looking statements include statements regarding, among other things, Silverback's ability to bring new treatments to patients in need, and the progress and expected timing of Silverback's drug development programs and clinical trials. Factors that may cause actual results to differ materially include the risk that compounds that appeared promising in early research or clinical trials do not demonstrate safety and/or efficacy in later preclinical studies or clinical trials, the risk that Silverback may not obtain approval to market its product candidates, uncertainties associated with performing clinical trials, regulatory filings and applications, risks associated with reliance on third parties to successfully conduct clinical trials, the risks associated with reliance on outside financing to meet capital requirements, and other risks associated with the process of discovering, developing and commercializing drugs that are safe and effective for use as human therapeutics, and in the endeavor of building a business around such drugs. You are urged to consider statements that include the words "may," "will," "would," "could," "should," "believes," "estimates," "projects," "promise," "potential," "expects," "plans," "anticipates," "intends," "continues," "designed," "goal," or the negative of those words or other comparable words to be uncertain and forward-looking. For a further list and description of the risks and uncertainties that Silverback faces, please refer to Silverback's periodic and other filings with the Securities and Exchange Commission, which are available at www.sec.gov. Such forward-looking statements are current only as of the date they are made, and Silverback assumes no obligation to update any forward-looking statements, whether as a result of new information, future events or otherwise.

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