Immunophenotypes and Outcome of Philadelphia Chromosome-Positive and -Negative Thai Adult Acute Lymphoblastic Leukemia

Little evidence exists in Asian countries regarding the incidence, immunologic characteristics, and clinical outcomes of adult patients with Philadelphia chromosome-positive (Ph+) and -negative (Ph-) acute lymphoblastic leukemia (ALL). In this study, we prospectively studied 324 Thai adult acute leukemia patients, 79 (24%) of whom were identified as having ALL. Immunophenotyping was performed by 5-parameter flow cytometry, and karyotyping was conducted by standard banding methods. The Ph chromosome was detected in 18.5% of cases. The mean age of Ph+ ALL patients was 29 years (50% male), and that of Ph- ALL patients was 33 years (62% female). The Ph+ ALL patients had significantly higher white blood cell (WBC) counts (mean, 93 x 10(9)/L), with 67% having WBC counts higher than 50 x 10(9)/L. In contrast, most Ph- ALL patients had WBC counts lower than 50 x 10(9)/L (mean, 36 x 10(9)/L; P < .05). CD10 and CD34 were more highly expressed in the Ph+ ALL patients (mean expression, 83% and 87%, respectively) than in the Ph- ALL patients (45% and 57%; P < .005). The aberrant expression of myeloid antigens, including CD33 and CD13, was also significantly observed in the Ph+ ALL patients. The median survival time of Ph+ ALL patients was 8 months, compared with 22 months for the Ph- ALL patients. In conclusion, immunophenotyping results showed that Ph+ ALL in Thai adults arises from B-cells at an earlier stage of development. Extreme leukocytosis, a younger age, male sex, high expression levels of CD10 and CD34, aberrant myeloid antigens, and poorer rates of survival appeared to be associated with the Ph chromosome in Thai adult ALL cases. The incidence of the Ph chromosome among Thai adult ALL patients was not different from that found in Western countries.