Sutro Biopharma, Inc. announced that its research collaborators at Fred Hutchinson Cancer Research Center presented data from the Compassionate Use Program on anti-leukemic activity of STRO-002, a novel folate receptor-a (FR-a) targeting ADC, in pediatric patients with relapsed/refractory CBFA2T3-GLIS2 (CBF/GLIS) acute myeloid leukemia (AML), commonly known as RAM phenotype AML, in an oral presentation at the 64th American Society of Hematology Annual Meeting and Exposition (ASH 2022) in New Orleans, LA. STRO-002 was provided to 17 pediatric patients with CBF/GLIS subtype AML on a compassionate use basis. Clinical results from these patients were compiled by Sutro and presented as an oral presentation by Soheil Meshinchi, M.D., Ph.D., Professor, Clinical Research Division, at Fred Hutchinson Cancer Research Center; Professor, Division of Pediatric Hematology-Oncology, at the University of Washington School of Medicine; and Principal Investigator for the program, titled, “Anti-Leukemic Activity of STRO-002 a Novel Folate Receptor-a (FR-a)-Targeting ADC in Relapsed/Refractory CBFA2T3-GLIS2 AML.” CBF/GLIS subtype AML is a rare, serious and life-threatening disease affecting pediatric patients with a median age of 1.5 years1 and the prevalence of CBF/GLIS in childhood is approximately 1 to 3% of pediatric AML cases1. These high-risk children with AML have an extremely poor prognosis with a 5-year overall survival of approximately 20%2. Patients are highly refractory to standard of care therapies and there are currently no approved therapies specifically targeting CBF/GLIS subtype AML.
Recent studies have shown that FOLR1, which encodes for FolRa, is silent in normal hematopoiesis, but is uniquely induced by the CBF/GLIS fusion3. Preclinical data presented last year at ASH 2021 demonstrated that patients with CBF/GLIS AML may benefit from STRO-002. STRO-002 is an optimized FolRa-targeting antibody-drug conjugate (ADC) with a drug-antibody ratio (DAR) of 4, which is precisely conjugated using non-natural amino acids to stable protease-cleavable linkers and hemiasterlin-derivative warheads. STRO-002 potentially has a dual mechanism of action against the tumor through cytotoxic killing and through inducing immunogenic cell death. STRO-002 was designed with Sutro's proprietary cell-free protein synthesis and site-specific conjugation platform, which enables precise design, rapid empirical optimization, and manufacture of site-specific homogenous ADCs.