Quantification of expression of antigens targeted by antibody-based therapy in chronic lymphocytic leukemia.
OBJECTIVE
Anti-CD20 (rituximab), anti-CD52 (alemtuzumab), anti-CD22 (BL22, HA22), and anti-CD25 (Oncotac) are therapeutic options that are the mainstay or in preclinical development for the treatment of chronic lymphocytic leukemia (CLL). Studies suggest that levels of surface antigen expression may affect response to monoclonal antibody-based therapy.


METHODS
Using the flow cytometric Quantibrite method (BD Biosciences, San Jose, CA) to determine antibodies bound per cell, we quantified the levels of surface expression of CD20, CD22, CD25, and CD52 in CLL cells from 28 untreated patients.


RESULTS
The CLL cells in all cases expressed CD20, CD22, and CD52 but 4 (14%) cases were negative for CD25. Although the ranking of levels of expression from highest to lowest was CD52, CD20, CD22, and CD25, the level of antigen expression on any specific case could not be accurately predicted.


CONCLUSIONS
Quantification of antigens might be useful in evaluating new antigens to target for therapy and may provide a systematic approach to selecting individualized therapy in CLL.
Flow Cytometry Unit, Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 10 Center Dr, Bethesda, MD, 20892; stetler@mail.nih.gov.
Prashant R
PR
Tembhare
Gerald
G
Marti
Adrian
A
Wiestner
Heba
H
Degheidy
Mohammed
M
Farooqui
Robert J
RJ
Kreitman
Gregory A
GA
Jasper
Constance M
CM
Yuan
David
D
Liewehr
David
D
Venzon
Maryalice
M
Stetler-Stevenson
D000328:Adult; D000368:Aged; D000911:Antibodies, Monoclonal / Q000627:therapeutic use; D015703:Antigens, CD / Q000032:analysis*; D000951:Antigens, Neoplasm / Q000032:analysis* / Q000276:immunology; D000970:Antineoplastic Agents / Q000627:therapeutic use; D014408:Biomarkers, Tumor / Q000032:analysis* / Q000276:immunology; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D016130:Immunophenotyping; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000188:drug therapy / Q000276:immunology*; D008297:Male; D008875:Middle Aged
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000951:Antigens, Neoplasm; D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor
Alemtuzumab; Antibody therapy; Chronic lymphocytic leukemia; Quantitative flow cytometry; Rituximab