Infant Lymphoblastic Leukemia: A Single Center Experience

Infantacute lymphoblastic leukemia (ALL) is a rare disease and consist of 4-5% of all childhood ALL. Despite improved survival rates of childhood ALL, infants with ALL have a worse prognosis . There were 206 patients diagnosed with ALL at Hacettepe University, Pediatric Hematology Department between 1 January 2008 and 31 December 2016, 11 out of 206 (5.3%) were diagnosed as infant ALL. We aimed to evaluate clinical findings, laboratory results and treatment outcome of our infant ALL patients retrospectively. There were 9 boys and two girls with a median age of 8 months (range 1-12 months) and nine out of 11 (82%) were older than 6 months of age at the initial diagnosis. Interestingly 2 of 3 siblings born from spontaneous triplet pregnancy diagnosed at the same time when they were 7 months old while the other sibling diagnosed 4 months later when he was 11 months old. Physical examination revealed hepatosplenomegaly in 10 out of 11 patients and 1 patient had extramedullary involvement with subcutaneous nodules on the forehead. On admission median WBC count was found 202x10^-9/L (range 37.4-739x10^-9/L) with a median hemoglobin level 9 g/dL (range 2.6-12.9 g/dL) and median platelet count 81x10^-9/L (range10- 314x10^-9/L). Immunophenotyping revealed CALLA+ B cell leukemia in 3 patients, CALLA- B cell in 6 patients and T cell leukemia in 2 patients. Cytogenetic analysis showed t(4;11) positivity in 4 patients and 3 of them were spontaneous triplets. Initial CNS involvement were positive in 2 of the patients. Eight patients (73%) were treated with Interfant protocols (Interfant 99 (n=4), Interfant 06 (n=4)) and 3 patients received Modified St. Jude Total XV protocol. Relapse were observed in 2 patients (one had both CNS and bone marrow relapse one year after the completion of chemotherapy and the other experienced an early bone marrow relapse at the 7^thmonth of the treatment). Hematopoetic stem cell transplantation (HSCT) was performed in five patients from matched related donor (n=2), unmatched related donor(n=1), and matched unrelated donor(n=2). Moreover, relapse after HSCT was observed in 2 patients 3 and 4 months later; one received second transplantation and survived while the other died because of progressive disease. Four of the five patients who had HSCT survived 74 months, 45, 18 and 13 months after the initial diagnosis, respectively. After a median of 18 months (range 4- 74 months ) follow-up period 6 patients are alive (45 %) and on remission 4 after HSCT and 2 with only chemotherapy. Infant leukemia usually presents with high hyperleucocytosis and extramedullary involvement. The prognosis is poor and international colloborative studies reprorted that 4 year -event free survival rates were between 28-54%. Our results suggest that bone marrow transplantation seems to be a good and efficient choice of treatment. However there is still a big issue to decide which patient should go under transplantation and more studies are needed to reevaluate the eligibility criteria for HSCT in this group of patients. Moreover to the best of our knowledge infant leukemia in triplets without monozygocity were first time reported.