Myeloid antigen expression in childhood acute lymphoblastic leukemia.

The clinical relevance of myeloid antigen expression in childhood ALL as prognostic factor remains controversial. Some studies showed that children with myeloid-positive ALL had a poorer clinical outcome compared with those of meloid-negative ALL patients. In our population, myeloid antigen was expressed in 25% of ALL patients. They were treated with Indonesia 2006 ALL protocol. ABSTRACT The frequency of acute lymphoblastic leukemia (ALL) patients expressing myeloid antigens on their ALL cells varies between 5-36% in several different studies. The clinical relevance of myeloid antigen expression in childhood ALL is controversial. In Indonesian patients no data were present. Therefore, in Yogyakarta, Indonesia, we analyzed 239 ALL patients who were immunophenotyped including myeloid markers (CD13, CD33, CD117 and/or cMPO). Myeloid antigen expression was found in 25% of patients. Expression of myeloid antigen in B-lineage leukemia was 27%, in T-lineage leukemia it was 18% (p=0.15). No association was found between myeloid antigen expression and clinical or biological features. In the whole cohort of patients we did not find a significant association between myeloid antigen expression and survival although leukemia free survival at 4 years was higher in the myeloid-negative patients (80% ± 5%) compared to myeloid-positive patients (67% ± 8%). Interestingly, in TALL patients, expression of myeloid antigens was an independent adverse prognostic factor for event-free survival (hazard ratio: 3.26, 95%CI: 1.06 – 9.98, p=0.04). In conclusion, in the Indonesian ALL population, in particular myeloid antigen expressing TALL patients showed shorter event-free survival, possibly due to higher chances of induction failure or relapse.