Silverback Therapeutics Announces Clinical Supply Agreement with Regeneron to Evaluate SBT6050 in Combination with Libtayo® (cemiplimab), initially in HER2-expressing Non-Small Cell Lung and Gastric Cancers

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 a clinical supply agreement with Regeneron for Libtayo® (cemiplimab). The supply agreement supports the evaluation of Libtayo®, a PD-1 inhibitor, in combination with SBT6050, 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.

“SBT6050’s unique ability to activate both innate and adaptive immune responses has the potential to enhance and expand the effectiveness of a PD-1 inhibitor in HER2-expressing solid tumors,” said Naomi Hunder, M.D., Chief Medical Officer of Silverback. “We are eager to complete the ongoing dose escalation of SBT6050 combined with a PD-1 inhibitor, and look forward to working with Regeneron as we begin tumor-specific expansion cohorts.”

In the first quarter of 2021, Silverback initiated treatment in Part 3 of the Phase 1/1b study to evaluate the activity of SBT6050 in combination with a PD-1 inhibitor in dose escalation. Under the terms of the agreement, Silverback will expand the ongoing Phase 1/1b trial to evaluate the combination of SBT6050 and Libtayo® in tumor-specific dose expansion cohorts, initially in HER2-expressing non small cell lung cancer (“NSCLC”) and gastric cancer.

Libtayo® is a PD-1 blocking antibody being jointly developed and commercialized by Regeneron and Sanofi. Libtayo® is approved for the first-line treatment of patients with advanced NSCLC whose tumors have high PD-L1 expression (tumor proportion score ≥50%), as determined by an FDA-approved test, with no EGFR, ALK, or ROS1 aberrations, for adults with metastatic cutaneous squamous cell carcinoma (“CSCC”) or locally advanced CSCC who are not candidates for curative surgery or curative radiation, and for patients with advanced basal cell carcinoma previously treated with a hedgehog pathway inhibitor (“HHI”) or for whom an HHI is not appropriate that is either locally advanced (full approval) or metastatic (accelerated approval).

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.

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