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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
When a blood or bone marrow is ordered, a panel specific to the desired antibody and a professional interpretation will always be charged. The panel will be charged based on number of markers tested (FIRST for first marker, ADD1 for each additional marker). The interpretation will be based on markers tested in increments of 2 to 8, 9 to 15, or 16 and greater.
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-CD52 (Campath-1H): B-cell chronic lymphocytic leukemia and T-cell disorders
-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).
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.
For the most appropriate interpretation, 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
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 appropriate, the normal cellular counterparts that correspond to the therapeutic monoclonal antibody target.
A complete diagnostic B-cell, T-cell, or acute immunophenotyping panel will not be performed and must be ordered separately (LCMS / 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.
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. Shanafelt TD, Geyer SM, Bone ND, et al: CD49D expression is an independent predictor of overall survival in patients with CLL: a prognostic parameter with therapeutic potential. Br J Haematol 2008;140:537-546