– Nonclinical data for STRO-002 and STRO-001 are shared in two oral presentations at the 63rd American Society of Hematology Annual Meeting

SOUTH SAN FRANCISCO, Calif, Dec. 13, 2021 – Sutro Biopharma, Inc. (NASDAQ: STRO), a clinical-stage drug discovery, development and manufacturing company focused on the application of precise protein engineering and rational design to create next-generation cancer and autoimmune therapeutics, today announced that its research collaborators at the Fred Hutchinson Cancer Research Center presented nonclinical data of STRO-002 and STRO-001 in two oral presentations at the 63rd American Society of Hematology Annual Meeting (ASH 2021) in Atlanta, Georgia. The research was conducted by investigators from the laboratory of Soheil Meshinchi, M.D., Ph.D., 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.

Dr. Meshinchi commented, “Using a computational approach, we have identified FOLR1, or FolRα, as an actionable target for high-risk pediatric AML; and CD74 as an actionable target in adult and pediatric AML and ALL. We further demonstrated that STR0-002 effectively targets a high-risk AML subtype and STRO-001 effectively targets AML and ALL cells that express CD74, providing promising nonclinical data for possible treatment options.”

Nonclinical data was presented by Quy Le, Ph.D., Staff Scientist, Meshinchi Lab, Fred Hutchinson Cancer Research Center on Sutro’s folate receptor alpha (FOLR1 or FolRα) -targeting antibody-drug conjugate (ADC), STRO-002, as a potential therapeutic in a rare pediatric acute myeloid leukemia (AML) subtype expressing FolRα. RNA-sequencing data demonstrated that FOLR1 is uniquely expressed in CBFA2T3-GLIS2 fusion (CBF/GLIS) AML and absent in other AML subtypes and normal hematopoietic cell populations. Data from an AML cell line engineered to express FOLR1 and CBF/GLIS-transduced cord blood hematopoietic stem/progenitor cells (CB HSPCs) demonstrated high cytotoxicity of STRO-002. In FOLR1 positive and CBF/GLIS-transduced CB HSPCs xenograft models, STRO-002 demonstrated potent activity that led to complete leukemia clearance.

Nonclinical data was also presented by Quy Le, Ph.D., Staff Scientist, Meshinchi Lab, Fred Hutchinson Cancer Research Center on Sutro’s CD74-targeting ADC, STRO-001, as a potential therapeutic in AML and acute lymphoblastic leukemia (ALL). Data from AML and ALL cell lines, as well as from nonclinical xenograft models, demonstrated robust in vitro and in vivo cytotoxicity of STRO-001 on cells expressing high- to -moderate levels of CD74, with no cytotoxicity observed in cells without CD74 expression. Potent anti-leukemia activity was also demonstrated in three primary AML patient samples with varied CD74 expression levels.

Dr. Arturo Molina, Sutro’s Chief Medical Officer added, “These nonclinical data presented by collaborators at Fred Hutchinson Cancer Research Center demonstrates the potential of targeted ADCs as therapeutics for AML and ALL. These data provide additional validation for an FolRα- and CD74-antigen directed approach, as our clinical studies for STRO-002 in ovarian and endometrial cancers and STRO-001 in B cell malignancies, respectively, continue to enroll patients.”

About Sutro Biopharma

Sutro Biopharma, Inc., located in South San Francisco, is a clinical-stage drug discovery, development and manufacturing company. Using precise protein engineering and rational design, Sutro is advancing next-generation oncology therapeutics.

Sutro’s proprietary and integrated cell-free protein synthesis platform XpressCF® and site-specific conjugation platform XpressCF+™ led to the discovery of STRO-001 and STRO-002, Sutro’s first two internally-developed ADCs. STRO-001 is a CD74-targeting ADC currently under investigation in a Phase 1 clinical trial for patients with advanced B-cell malignancies and was granted Orphan Drug Designation by the FDA for multiple myeloma. STRO-002, a folate receptor alpha (FolRα)-targeting ADC, is currently being investigated in a Phase 1 clinical trial for patients with ovarian and endometrial cancers and was granted Fast Track designation by the FDA for ovarian cancer. A third product candidate, CC-99712, a BCMA-targeting ADC, which is part of Sutro’s collaboration with Bristol Myers Squibb, formerly Celgene Corporation, is enrolling patients for its Phase 1 clinical trial of patients with multiple myeloma and has received Orphan Drug Designation from the FDA. A fourth product candidate, M1231, a MUC1-EGFR, first-in-class bispecific ADC, which is part of Sutro’s collaboration with Merck KGaA, Darmstadt, Germany, known as EMD Serono in the U.S. and Canada (EMD Serono), is enrolling patients for its Phase 1 clinical trial of patients with metastatic solid tumors, non-small cell lung cancer (NSCLC) and esophageal squamous cell carcinoma. These four product candidates resulted from Sutro’s XpressCF® and XpressCF+™ technology platforms. Bristol Myers Squibb and EMD Serono have worldwide development and commercialization rights for CC-99712 and M1231, respectively, for which Sutro is entitled to milestone or contingent payments and tiered royalties.

Sutro is dedicated to transforming the lives of cancer patients by creating medicines with improved therapeutic profiles for areas of unmet need. To date, Sutro’s platform has led to ADCs, bispecific antibodies, cytokine-based immuno-oncology therapies, and vaccines directed at precedented targets in clinical indications where the current standard of care is suboptimal.

The platform allows it to accelerate discovery and development of potential first-in-class and best-in-class molecules through rapid and systematic evaluation of protein structure-activity relationships to create optimized homogeneous product candidates. In addition to developing its own oncology pipeline, Sutro is collaborating with select pharmaceutical and biotechnology companies to discover and develop novel, next-generation therapeutics.

Follow Sutro on Twitter, @Sutrobio, and at https://www.sutrobio.com to learn more about our passion for changing the future of oncology.

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