Journal of Leukemia
Open Access

Abstract

Thymic Immunophenotype, and Expression of CD4 and Myeloid Antigens is Associated with Outcome in Adult Patients with T–Cell Acute Lymphoblastic Leukemia

Areej Al Mugairi, Bakul I Dalal, Steven Pi, Soo Yeon Lee, Nikisha S Khare, Jason Pal, Alok Vakil, Adam Bryant, Sally Lau and Yasser R Abou Mourad

Background: In adult patients with T?cell acute lymphoblastic leukemia (T?aALL), age, WBC count and cytogenetics are used for prognostic stratification. We report the prognostic significance of immunophenotype in T? aALL patients. Methods: We analyzed 27 T?aALL patients treated at the Leukemia-BMT Program of British Columbia between 1989 and 2010 using a standardized protocol for diagnosis, treatment and follow up. The immunophenotyping raw data was re-analyzed to record positivity (?20% blasts positive), number of blasts positive, and intensity and homogeneity of expression. Thymic phenotype (TP) and expression of myeloid antigens (My+) were defined as any one of CD1a+ or dual expression of CD4 and CD8, and any one of CD13+, CD33+ or CD117+ respectively. Results: Twenty-two (81%) T?aALL patients achieved complete remission (CR); of these, 7(32%) relapsed within 5-22 months (median 15 months). The relapse-free survival (RFS) and overall survival (OS) were 1 -119 (median 18) months and 1-119 (median 25) months respectively. Frequency of CD1a+, CD4+, TP+ and My+ was 58%, 58%, 66% and 50% respectively. Expression of T-cell antigens CD1a, CD4, and TP+ status were favorably associated with outcome: CD1a+ status with OS (p=0.017), CD4+ status with RFS (p=0.015) and OS (p=0.005), TP+ status with CR (p=0.028) and OS (p=0.024). My+ status was adversely associated with CR (p=0.013) and OS (p=0.026). Conclusions: In T?aALL patients, CD1a+, CD4+ and TP+ are favorably, and My+ status are adversely associated with outcome. The percentage of positive blasts and intensity and uniformity of staining for different antigens shows wide variations.