- CD22 is a B-lineage-restricted, transmembrane phosphoglycoprotein of the Ig superfamily that is widely expressed on B-cell malignancies including 96% to 100% of pediatric Bprecursor ALL. Therefore, CD22 represents a promising target. Encouraging responses targeting CD22 with an antibody based immunoconjugate have been seen in patients, including children, with recurrent and refractory ALL. This will be the first in human testing of anti-CD22 CAR adoptive cell therapy.