Characterization of CD22 expression in acute lymphoblastic leukemia

• Published in: Pediatric blood & cancer Vol. 62; no. 6; pp. 964 - 969
• Main Authors: Shah, Nirali N., Stevenson, Maryalice Stetler, Yuan, Constance M., Richards, Kelly, Delbrook, Cindy, Kreitman, Robert J., Pastan, Ira, Wayne, Alan S.
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01.06.2015; Wiley Subscription Services, Inc
• Subjects: Acute lymphoblastic leukemia; Adolescent; Adult; Antigens; Blood cancer; Cancer; CD22; CD22 antigen; Chemotherapy; Child; Child, Preschool; Children; Chromosomes, Human, Pair 11; Enzyme-linked immunosorbent assay; Hematology; Histone-Lysine N-Methyltransferase; Humans; Infant; Leukemia; Lymphatic leukemia; Monoclonal antibodies; monoclonal antibody; Myeloid-Lymphoid Leukemia Protein - genetics; Oncology; Pediatrics; Pharmacokinetics; Precursor Cell Lymphoblastic Leukemia-Lymphoma - drug therapy; Precursor Cell Lymphoblastic Leukemia-Lymphoma - immunology; relapse; Sialic Acid Binding Ig-like Lectin 2 - analysis; Sialic Acid Binding Ig-like Lectin 2 - antagonists & inhibitors; Therapeutic applications; Therapeutic targets; United States > US; monoclonal antibody; acute lymphoblastic leukemia; relapse; CD22
• ISSN: 1545-5009; 1545-5017; 1545-5017
• DOI: 10.1002/pbc.25410

Background CD22 is a B‐lineage differentiation antigen that has emerged as a leading therapeutic target in acute lymphoblastic leukemia (ALL). Procedure Properties of CD22 expression relevant to therapeutic targeting were characterized in primary samples obtained from children and young adults with relapsed and chemotherapy refractory B‐precursor (pre‐B) ALL. Results CD22 expression was demonstrated in all subjects (n = 163) with detection on at least 90% of blasts in 155 cases. Median antigen site density of surface CD22 was 3,470 sites/cell (range 349–19,653, n = 160). Blasts from patients with known 11q23 (MLL) rearrangement had lower site density (median 1,590 sites/cell, range 349–3,624, n = 20 versus 3,853 sites/cell, range 451–19,653, n = 140; P = <0.0001) and 6 of 21 cases had sub‐populations of blasts lacking CD22 expression (22%–82% CD22 +). CD22 expression was maintained in serial studies of 73 subjects, including those treated with anti‐CD22 targeted therapy. The levels of soluble CD22 in blood and marrow by ELISA were low and not expected to influence the pharmacokinetics of anti‐CD22 directed agents. Conclusions These characteristics make CD22 an excellent potential therapeutic target in patients with relapsed and chemotherapy‐refractory ALL, although cases with MLL rearrangement require close study to exclude the presence of a CD22‐negative blast population. Pediatr Blood Cancer Published 2015. This article is a U.S. Government work and is in the public domain in the USA.