Sutro Biopharma Achieves “First in Human” Milestone in Cytokine Derivatives Collaboration with Merck

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 the first patient has been dosed in a Phase 1 study of an investigational candidate resulting from the collaboration between Sutro and Merck, known as MSD outside the United States and Canada, for the development of a novel cytokine derivative therapeutic for the treatment of cancer. As a result of this milestone, Sutro will receive a $10 million payment from Merck.

“We are pleased with the progress of this next-generation biologic candidate, from discovery to clinical development for patients with advanced or metastatic solid tumors,” said Bill Newell, Chief Executive Officer of Sutro. “This milestone reflects the strong synergistic collaboration between Merck’s biological expertise in the field of immuno-oncology and Sutro’s prowess in designing, engineering, and manufacturing complex biologics that incorporate site-specific conjugation. We are excited about the potential this therapeutic may have for cancer patients.”

Under the terms of the July 2018 collaboration agreement between Sutro and Merck, Sutro has been primarily responsible for preclinical research and development, as well as manufacturing, of cytokine derivatives utilizing Sutro’s proprietary cell-free protein synthesis and site-specific conjugation platforms, XpressCF® and Xpress CF+®. Merck has exclusive worldwide rights to therapeutic candidates derived from the collaboration.

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, a biologic in clinical studies for the treatment of solid tumors; and with Astellas Pharma (Astellas) on a 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.