[1197] CD52 Expression in T Cell Lymphomas

Z Ghorab, JW Wong, R Buckstein, M Cheung, S Nofech-Mozes. Sunnybrook Health Sciences Centre, Toronto, Canada

Background: Alemtuzumab (CAMPATH-1H) is a humanized monoclonal antibody that targets CD52, a cell surface glycoprotein, and is currently used in the treatment of several hematologic malignancies. The drug has an antitumor effect mediated by human complement and via antibody dependent cellular cytotoxicity, but is also associated with significant toxicity. Given the poor response to conventional chemotherapy in T cell lymphomas, there has been increasing interest in evaluating the addition of novel therapies such as CAMPATH for these conditions. However, limited data on the level of expression of the CD52 target antigen are available in T cell neoplasms.
Design: We evaluated CD52 expression using immunohistochemistry (Rat anti-human clone YTH34.5, Serotec, Oxford, UK1:400) on formalin fixed paraffin embedded tissue from 52 consecutive cases accessioned between March 2005 and July 2008 in the department of Anatomic Pathology at Sunnybrook Health Sciences Centre. Tumors were classified by a hematopathologist according to the WHO classification. The CD52 stain was considered positive when the neoplastic cells exhibited strong cytoplasmic or membranous staining. Staining in less than 30% of the cells was reported as focal positive. Nuclear staining was considered nonspecific.
Results: CD52 was expressed in the cytoplasm/membrane of 24 (46.2%) cases. The staining was focal in 7 out of 24 (29.1%). CD52 was positive in: 11/23 (47.8%) peripheral T cell lymphoma- unspecified; 1/6 (16%) anaplastic large cell lymphoma; 3/5 angioimmunoblastic T-cell lymphoma; 2/5 (40%) mycosis fungoides involving lymph nodes; 1/4 (25%) precursor T lymphoblastic lymphoma; 3/3 (100%) adult T cell leukemia/lymphoma; 0/2 (0%) NK/T-cell lymphoma; 1/2 (50%) enteropathy-type T- cell lymphoma; and 2/2 (100%) subcutaneous panniculitis-like T-cell lymphoma. The expression of CD52 was not associated with disease site (12/28 nodal vs. 12/24 extranodal: p = 0.78).
Conclusions: CD52 expression is variable among T cell neoplasms. Almost half of all T-cell non-Hodgkin's lymphomas are CD52 positive and PTCL unspecified are CD52 positive. The role of CD52 expression as a predictor of response to CAMPATH targeted therapy in T cell lymphoma should be further evaluated.
Category: Hematopathology

Tuesday, March 10, 2009 9:30 AM

Poster Session III # 110, Tuesday Morning