–Results from compassionate use program highlight promising activity of STRO-002 in children with rare form of acute myeloid leukemia, that is highly refractory to all standard-of-care therapies–

SOUTH SAN FRANCISCO, Calif., November 3, 2022 – Sutro Biopharma, Inc. (Sutro or the Company) (NASDAQ: STRO), a clinical-stage oncology company pioneering site-specific and novel-format antibody drug conjugates (ADCs), today announced that data from the Company’s compassionate use program on anti-leukemic activity of STRO-002, a novel folate receptor-α (FR-α) targeting ADC, in infants and children with relapsed/refractory CBF2AT3-GLIS2 acute myeloid leukemia (AML) will be reviewed in an oral presentation at the 64th American Society of Hematology Annual Meeting and Exposition (ASH). The meeting will take place December 10 – 13, 2022 in New Orleans, LA.

Soheil Meshinchi, M.D., Ph.D., Principal Investigator for the compassionate use program with STRO-002 in relapsed/refractory CBF2AT3-GLIS2 AML, will deliver the oral presentation at 10:45 a.m. CST on December 10, 2022. Dr. Meshinchi is Professor, Clinical Research Division, at Fred Hutchinson Cancer Research Center and Professor, Division of Pediatric Hematology-Oncology, at the University of Washington School of Medicine.

“As a patient-driven company, we at Sutro are extremely pleased that STRO-002— which we are presently developing in ovarian cancer—had a profound effect in a pediatric patient group with a rare form of AML, for which treatment options are limited,” said Bill Newell, Sutro’s Chief Executive Officer. “Among the highlights from our compassionate use program, there were a number of complete responses, which is particularly encouraging considering these patients are typically refractory to standard-of-care. We look forward to an oral presentation of the full data set at ASH in December.”

Oral Presentation Details:

Abstract Title: Anti-Leukemic Activity of STRO-002 a Novel Folate Receptor-α (FR-α)-Targeting ADC in Relapsed/Refractory CBF2AT3-GLIS2 AML
Session: Acute Myeloid Leukemias: Investigational Therapies, Excluding Transplantation and Cellular Immunotherapies: Relapsed/Refractory AMLS Session
Date: Saturday, December 10, 2022
Session Time:  9:30 a.m. – 11:00 a.m. CST
Presentation Time: 10:45 a.m. CST

The accepted ASH abstract will be made available today on the congress platform here, and a whitepaper with details about this rare indication and Sutro’s compassionate use program is now available on the Company’s website here. Following the conference, the presentation materials will be available in the “Clinical/Scientific Presentation and Publication Highlights” section of Sutro Biopharma’s website at www.sutrobio.com.

About Sutro Biopharma

Sutro Biopharma, Inc., headquartered in South San Francisco, is a clinical-stage oncology company pioneering site-specific and novel-format antibody drug conjugates (ADCs). Sutro has two wholly owned ADCs in the clinic—STRO-002, a folate receptor alpha (FolRα)-targeting ADC, in clinical studies for ovarian and endometrial cancers; and STRO-001, a CD74-targeting ADC, in clinical studies for B-cell malignancies. Additionally, Sutro is collaborating with Bristol Myers Squibb (BMS) on CC-99712, a BCMA-targeting ADC in the clinic for patients with multiple myeloma; with Merck KGaA, Darmstadt, Germany, known as EMD Serono in the U.S. and Canada (EMD Serono), on M1231, a MUC1-EGFR bispecific ADC in clinical studies for patients with solid tumors, particularly non-small cell lung cancer (NSCLC) and esophageal squamous cell carcinoma; with Merck, known as MSD outside of the United States and Canada, on MK-1484, a selective IL-2 agonist in clinical studies as a monotherapy and in combination with pembrolizumab for the treatment of solid tumors; and with Astellas Pharma (Astellas) on novel modality, immunostimulatory antibody-drug conjugates (iADCs). Sutro’s platform technology also enabled the spin out of Vaxcyte (Nasdaq: PCVX) and the creation of VAX-24, a 24-valent pneumococcal conjugate vaccine in clinical studies for the prevention of invasive pneumococcal disease. Sutro’s rational design and precise protein engineering has enabled six product candidates in the clinic. Follow Sutro on Twitter, @Sutrobio, and at www.sutrobio.com to learn more about our passion for changing the future of oncology.

Investor Contact

Annie J. Chang
Sutro Biopharma
(650) 801-5728
ajchang@sutrobio.com

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Solebury Strategic Communications
(914) 450-0349
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