Hematopoietic stem cell involvement in BCR-ABL1–positive ALL as a potential mechanism of resistance to blinatumomab therapy

Key Points BCR-ABL1–positive cells outside the B-lineage compartment are found in 40% of adult patients with BCR-ABL1–positive BCP-ALL. Selection of preexisting CD19– subclones is a potential source of tumor escape after CD19-targeted therapies in adult Philadelphia chromosome–positive ALL.