Variable CD52 expression in mature T cell and NK cell malignancies: implications for alemtuzumab therapy

Abstract

The anti-CD52 antibody alemtuzumab has been explored as a novel targeted therapy in T cell malignancies. To assess the suitability of alemtuzumab therapy, we carried out a comprehensive study of CD52 expression using flow cytometry (FC) in 78 untreated patients diagnosed with mature T/natural killer (NK) cell neoplasms, including 34 adult T cell leukaemia/lymphomas (ATLL), two anaplastic large cell lymphomas (ALCL), three angioimmunoblastic T cell lymphomas (AITL), 16 cutaneous T cell lymphomas (CTCL), four extra-nodal T/NK cell lymphomas (ENT/NKCL), four hepatosplenic T cell lymphomas (HSTCL), 13 peripheral T cell lymphomas, not otherwise specified (PTCL-NOS) and two T-prolymphocytic leukaemia (T-PLL). The level of CD52 expression was quantified using QuantiBRITE standard beads. The level of CD52 expression varied widely within each diagnostic category. All AITL, HSTCL and T-PLL cases were CD52-positive and the frequency of CD52 expression was high in PTCL-NOS (92.3%), ATLL (94.1%) and CTCL (87.5%), implying a rational role for alemtuzumab in the treatment of these diseases; however, CD52 expression was low in ALCL (50%) and ENT/NKCL (25%). FC testing for cell surface expression of CD52 is indicated in patients with T/NK cell malignancies being considered for alemtuzumab therapy. Further studies are necessary to determine if the level of CD52 expression correlates with response to therapy.

Figure 1

CD52 Expression in T Cell Malignancies. CD52 expression as measured by anti-CD52-PE antibody. A. High level CD52 expression (ABC-24,894). B. Low level CD52 expression (ABC-1,317). C. Negative for CD52. X axis- CD3, Y-axis CD52, oval indicates malignant cells (based upon complete immunophenotypic data)

Figure 2

CD52 Expression in NK/T Cell Malignancies. CD52 expression as measured by anti-CD52-PE antibody. A. Positive for CD52 expression (ABC-1,336). B. Negative for CD52. X axis- CD56, Y-axis CD52, oval indicates malignant cells (based upon complete immunophenotypic data)