Therapeutic Antibody by Flow Cytometry
Detecting cell surface antigens on malignant cells that are potential therapeutic antibody targets
Determining the eligibility of patients for monoclonal antibody therapies
Monitoring response to the therapeutic antibody
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Monoclonal antibodies are critical tools for detecting cellular antigens in various hematologic diseases and are used to provide critical diagnostic information. Monoclonal antibodies are also used as therapeutic agents in a variety of hematologic diseases. For example:
-Anti-CD20 (Rituxan): B-cell malignant lymphomas and multiple myeloma
-Anti-CD25: B-cell and T-cell leukemias and lymphomas
-Anti-CD52 (Campath-1H): B-cell chronic lymphocytic leukemia and T-cell disorders
-Anti-CD33: acute myeloid leukemia
-Anti-CD49d: estimates prognosis for B-cell chronic lymphocytic leukemia patients
This list will undoubtedly expand over time to include other antibodies.
It may be necessary to document expression of these markers by the malignant cells prior to initiating the respective monoclonal antibody therapy. Expression of these markers may also be required for follow-up to monitor the impact of treatment on residual normal counterparts (eg, CD20-positive lymphocytes in patients treated with anti-CD20).
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Normal individuals have B-lymphocytes, T-lymphocytes, or myeloid cells that express the corresponding cell-surface antigens in question.
The immunophenotyping report will summarize the pattern of antigenic expression on malignant cells and, if necessary, the normal cellular counterparts that correspond to the therapeutic monoclonal antibody target.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
The requesting physician must provide the laboratory with:
-The therapeutic monoclonal antibody being used or considered
-The pertinent hematologic diseases that have been diagnosed or considered
-Any pertinent protocol requirements
A complete diagnostic B-cell, T-cell, or acute immunophenotyping panel will not be performed and must be ordered separately (LCMS/3287 Leukemia/Lymphoma Immunophenotyping by Flow Cytometry). In some cases, a limited morphologic evaluation will be performed. This test should not be used as a shortened diagnostic panel.
The distribution of these cellular antigens is well established in normal, reactive, and in various malignant disorders. The laboratory has several years of experience with therapeutic antibody monitoring of Mayo Clinic patients as part of the routine B-cell, T-cell, or acute immunophenotyping panels.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Davis AT: Monoclonal antibody-based therapy of lymphoid neoplasms: what's on the horizon? Semin Hematol 2000;37(4 Suppl 7):34-42
2. Czuczman MS, Grillo-Lopez AJ, White CA, et al: Treatment of patients with low-grade B-cell lymphoma with the combination of chimeric anti-CD20 monoclonal antibody and CHOP chemotherapy. J Clin Oncol 1999;17:268-276
3. Flynn JM, Byrd JC: Campath-1H monoclonal antibody therapy. Curr Opin Oncol 2000;12:574-581
4. Kreitman RJ, Wilson WH, Bergeron K, et al: Efficacy of the anti-CD22 recombinant immunotoxin BL22 in chemotherapy-resistant hairy-cell leukemia. N Eng J Med 2001;345:241-247
5. van der Velden VH, te Marvelde JG, Hoogeveen PG, et al: Targeting of the CD33-calicheamicin immunoconjugate Mylotarg (CMA-676) in acute myeloid leukemia: in vivo and in vitro saturation and internalization by leukemic and normal myeloid cells. Blood 2001;97:3197-3204