Background
Acute lymphoblastic leukemia (ALL) is a malignant blood disorder with a high prevalence in childhood, particularly in pediatric patients with B-cell ALL (B-ALL)[1]. Due to the continuous improvement in MICM precise staging and multi-drug combination chemotherapy regimens, the 5-year overall survival rate (OS) of pediatric patients with ALL has reached over 90% and the 5-year event-free survival rate (EFS) has reached 80%[2]. However, conventional chemotherapy has been shown to be ineffective for very high-risk pediatric patients. Philadelphia chromosome (Ph)-positive ALL was historically associated with very poor outcomes before the advent of tyrosine kinase inhibitors (TKIs)[3]. The long-term survival of pediatric patients with Ph+ ALL has significantly improved with the use of regimens combining TKI with chemotherapy. The CCCG-ALL-2015 study showed that the 4-year EFS and OS were 71.0% and 88.4%, respectively, for pediatric Ph+ ALL patients treated with TKI[4]. Nevertheless, while severe and life-threatening cardiovascular events, such as pulmonary arterial hypertension (PAH), have been reported in adults with chronic myeloid leukemia (CML) and Ph+ B-ALL patients receiving long-term TKI therapy[5], they have been rarely reported in pediatric patients. This study reports the clinical findings for two pediatric Ph+ ALL patients who showed PAH as a result of long-term dasatinib therapy at our department, and also reviews the relevant literature on the incidence of PAH during the course of dasatinib treatment.