A New Generation of Precisely Engineered CD74-Targeting ADC

SOUTH SAN FRANCISCO /PRNewswire/ -- Sutro Biopharma, Inc. (NASDAQ: STRO), has been granted Orphan Drug Designation by the United States Food and Drug Administration (FDA) for STRO-001 for the treatment of multiple myeloma. STRO-001 is a potential first-in-class antibody drug conjugate (ADC) targeting CD74, a protein highly expressed in B-cell malignancies such as multiple myeloma.

"There is a growing need for new treatment options for patients with multiple myeloma," commented Bill Newell, Sutro's Chief Executive Officer. "This Orphan Drug Designation is a great step towards advancing our uniquely designed STRO-001 that could bring new treatment options to patients in need."

STRO-001 was developed with Sutro's proprietary cell-free protein synthesis and site-specific conjugation platform, XpressCF+^™, which facilitate precision design and rapid empirical optimization of ADCs. Sutro's technology enables design and manufacture of a highly optimized single molecular species within the product, rather than the usual mixture of imprecisely conjugated antibodies that comprise an ADC development product made by conventional cell-based manufacturing platforms.

"STRO-001 was designed to directly target cancer cells to deliver a cytotoxic payload. Building upon our XpressCF+^™platform we plan to develop better options to treat tumors with greater precision," Bill Newell added.

STRO-001 is currently being studied in a Phase 1 clinical trial enrolling separate dose escalation cohorts for myeloma and B-cell lymphoma.

About Orphan Drug Designation

The Orphan Drug Designation Program provides orphan status to drugs and biologics which are defined as those intended for the safe and effective treatment, diagnosis or prevention of rare diseases/disorders that affect fewer than 200,000 people in the U.S., or that affect more than 200,000 persons but are not expected to recover the costs of developing and marketing a treatment drug.

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995, including, but not limited to, planned development activities and the potential benefits of the company's product candidates and platform. All statements other than statements of historical fact are statements that could be deemed forward-looking statements. Although the company believes that the expectations reflected in such forward-looking statements are reasonable, the company cannot guarantee future events, results, actions, levels of activity, performance or achievements, and the timing and results of biotechnology development and potential regulatory approval is inherently uncertain. Forward-looking statements are subject to risks and uncertainties that may cause the company's actual activities or results to differ significantly from those expressed in any forward-looking statement, including risks and uncertainties related to the company's ability to advance its product candidates, obtain regulatory approval of and ultimately commercialize its product candidates, the timing and results of preclinical and clinical trials, the company's ability to fund development activities and achieve development goals, the company's ability to protect intellectual property and other risks and uncertainties described under the heading "Risk Factors" in documents the company files from time to time with the Securities and Exchange Commission. These forward-looking statements speak only as of the date of this press release, and the company undertakes no obligation to revise or update any forward-looking statements to reflect events or circumstances after the date hereof.

Investor Contacts

John Graziano
Solebury Trout
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jgraziano@soleburytrout.com

Xuan Yang
Solebury Trout
+1 646-378-2975
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