Expression of CD1a, CD4 and Myeloid Antigens Correlate with Treatment Response and Survival in Adult T-Cell Acute Lymphoblastic Leukemia
Bakul I Dalal, Areej Al Mugairi, Steven Pi, Soo Yeon Lee, Nikisha S Khare, Jason Pal, Adam Bryant, Sally Lau, Yasser Abou Mourad. Vancouver General Hospital, Vancouver, BC, Canada; University of British Columbia, Vancouver, BC, Canada
Background: The risk stratification for T-cell acute lymphoblastic leukemia (T-ALL) is based on white blood cell (WBC) count, cytogenetics (CG) and response to induction therapy. The role of immunophenotype in T-ALL has been described in pediatric T-ALL, but its significance in adult cases has not been established.
Design: 1. Immunophenotype of all adult T-ALL patients diagnosed between 1989-2010 and uniformely treated with ALL-891a protocol was reviewed and re-analyzed.
2. Multiparameter flowcytometry was done on fresh bone marrow or blood specimens processed with stain-and-lyze technic. The antibody panel, the instrumentation, and the analysis strategies have evolved over the course of this study.
3. The data-files were re-analyzed, the graphs were re-interpreted, and the reports were reviewed. The leukemic cells were considered positive when ≥20% expressed the antigen, based on comparison with normal cell populations present in the specimen (where possible). The intensity of antigen expression was assessed according to the College of American Pathologists schema.
4. The expression of antigens and its intensity was correlated with achievement of complete remission (CR), relapse, relapse-free survival (RFS), and overall survival (OS).
Results: 1. Twenty-seven patients with T-ALL were reviewed; their median age was 27 years (17-66). There were 21 males and 6 females. There were 26 Caucasians and 1 South Asian.
2. Twenty-two (81%) patients achieved CR, and of them seven (32%) relapsed in 5-22 months. The median OS and RFS were 15 (1-119) and 18 (1-119) months respectively. CD1a and CD4 were positive in 8/14 (57%) and 14/24 (58%) of the cases.
3. CD1a positivity was associated with superior 24-month (7/7 vs 1/7, P= 0.002) and 60-month OS (4/4 vs 4/10, P= 0.04).
4. CD4 positivity was associated with higher frequency of CR (14/21 vs 0/3, P= 0.02), superior 24-month RFS (9/9 vs 5/12, P= 0.007), and superior 24-month (11/13 vs 3/11, P= 0.004) and 60-month OS (6/6 vs 8/18, P= 0.01).
5. Aberrant expression of myeloid antigens (CD13 or CD33 or CD117) was associated with inferior 24-month (3/12 vs 7/11, P= 0.06) and 60-month (0/5 vs 10/18, P= 0.02) and inferior 24-month RFS (0/8 vs 6/11, P= 0.02).
Conclusions: In adult T-ALL, expression of CD1a and CD4 are favorably and myeloid antigens are adversely associated with treatment response and survival.
Wednesday, March 6, 2013 9:30 AM
Poster Session V # 241, Wednesday Morning