Soluble CD22 as a tumor marker for hairy cell leukemia.
CD22 is an important immunotherapeutic target on B-cell malignancies, particularly hairy cell leukemia (HCL), but its soluble extracellular domain, sCD22, has not yet been reported in the blood. By immunoaffinity and enzyme-linked immunosorbent assay techniques using anti-CD22 monoclonal antibodies, we identified the 100-kDa extracellular domain of CD22 and an 80-kDa processed form in serum of patients with HCL. The median sCD22 level measured by enzyme-linked immunosorbent assay was 18 ng/mL for 93 patients with HCL. sCD22 levels varied from 2.1 to 163 ng/mL and were higher (P < .001) than 23 normal donors (median, 0.6 ng/mL). More than 95% of normal donors had sCD22 levels less than 1.9 ng/mL. sCD22 levels were proportional to concentrations of circulating HCL cells (P = .002), and HCL spleen size (P < .001). sCD22 levels normalized with complete but not partial response to treatment. sCD22 levels up to 300 ng/mL had less than a 2-fold effect on the cytotoxicity of the anti-CD22 recombinant immunotoxin BL22. sCD22 levels may be useful to follow in patients with HCL and may be more specific than sCD25 in patients with CD22(+)/CD25(-) disease. Trials are listed on www.cancer.gov as NCT00002765, NCT00021983, NCT00074048, NCT00085085, NCT00337311, and NCT00462189.
Matsushita
Kakushi
K
Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20854-4255, USA.
Margulies
Inger
I
Onda
Masanori
M
Nagata
Satoshi
S
Stetler-Stevenson
Maryalice
M
Kreitman
Robert J
RJ
D014408:Biomarkers, Tumor / Q000097:blood; D016022:Case-Control Studies; D019937:Diagnostic Techniques and Procedures; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D000922:Immunotoxins / Q000633:toxicity; D007943:Leukemia, Hairy Cell / Q000175:diagnosis* / Q000188:drug therapy; D008970:Molecular Weight; D051918:Sialic Acid Binding Ig-like Lectin 2 / Q000097:blood*; D012995:Solubility; D047368:Tumor Burden
D014408:Biomarkers, Tumor; D000922:Immunotoxins; D051918:Sialic Acid Binding Ig-like Lectin 2