Silverback Therapeutics to Present Data from its Phase 1/1b Clinical Trial of SBT6050 at the European Society for Medical Oncology (ESMO) 2021 Virtual Congress

Silverback Therapeutics, Inc. (Nasdaq: 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, today announced that interim data from the dose-escalation portion of its Phase 1/1b clinical trial evaluating SBT6050 as a monotherapy and in combination with pembrolizumab in patients with advanced or metastatic HER2-expressing or amplified solid tumors will be presented at the upcoming European Society for Medical Oncology (ESMO) 2021 Congress from September 16-21, 2021.

The accepted abstract, with a data cut-off date of April 4, 2021, is now available on the ESMO website. The upcoming poster will include additional data with a cut-off date of August 1, 2021. Details of the poster are as follows:

Title: "Interim results of a Phase 1/1b study of SBT6050 monotherapy and pembrolizumab combination in patients with advanced HER2-expressing or amplified solid tumors"
Poster Number: 209P
Presenter: Samuel J. Klempner, MD
Session Date and Time: The poster will be released virtually on Thursday, September 16th at 8:30 AM Central European Summer Time / 2:30 AM Eastern Time

Conference Call and Webcast on Thursday, September 16, 2021, at 6:30 AM ET

Silverback's management team will host a conference call on Thursday, September 16, 2021, at 6:30 AM ET following the release of the poster at the ESMO 2021 Virtual Congress. A live webcast, including slides, can be accessed through the Events section of the Company's website at https://ir.silverbacktx.com/news-events/events. An archived replay will be available shortly after the conclusion of the event.

About SBT6050

SBT6050 is the first of a new class of targeted immuno-oncology agents designed to direct a TLR8 agonist linker-payload to activate myeloid cells in tumors expressing moderate to high levels of HER2. TLR8 is expressed in myeloid cell types prevalent in human tumors and TLR8 agonism can activate a broad spectrum of anti-tumor immune mechanisms, including pathways involved in the innate and adaptive immune response. SBT6050 was specifically designed to bind to the HER2 sub-domain II, the pertuzumab epitope, to enable combinations with trastuzumab-based therapies. SBT6050 is currently being evaluated in a Phase 1/1b trial in patients with advanced or metastatic HER2-expressing or amplified solid tumors.

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.

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, applications and other interactions with regulatory bodies, the risks associated with reliance on third parties to successfully conduct clinical trials, the risks associated with reliance on outside financing to meet capital requirements, the risks associated with the COVID-19 global pandemic, 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.