AML with t(8;21) RUNX1-RUNX1T1

A 28-year-old man presents with pallor, fatigue, and a painful left thigh mass. CBC shows WBC 24,000/µL with 55% blasts, hemoglobin 7.8 g/dL, and platelets 44,000/µL. Peripheral smear demonstrates large myeloblasts with abundant cytoplasmic granules, long slender Auer rods, and prominent nucleoli. Bone marrow biopsy reveals 48% blasts with strong myeloperoxidase positivity and evidence of maturation toward neutrophils. Biopsy of the thigh mass confirms myeloid sarcoma. Cytogenetic analysis reveals the karyotype shown. The translocation marked **A** in the diagram generates a fusion transcript that acts as a dominant-negative inhibitor of the core binding factor complex. Which of the following best describes the mechanism by which this fusion protein impairs myeloid differentiation?