Dasatinib Restores Full Donor Chimerism in Animatinib - Resistant Ph+ ALL Childwith E255K Gene Mutation Relapse Dafter Allo HSCT

Abstract 4827

Philadelphia chromosome positive acute lymphoblastic leukemia is uncommon among children and very tough to treat. With chemotherapy alone, only 20–30% of children are cured, but tyrosine kinase inhibitors (TKIs) plus chemotherapy and allogeneic hematopoietic stem cell transplantation in 1^st complete remission has gradually high possibility of cure. Some recent papers also suggest that chemotherapy plus tyrosine kinase inhibitors (TKIs) may be the initial treatment of choice. Despite this, there is a few data about treatment after relapse.

We introduce a case of 15 years old boy with Philadelphia chromosome positive acute lymphoblastic leukemia early relapse after full-match related donor hematopoietic stem cell transplantation from his mother.

Both at the time of diagnosis and at relapse time the patient had various cytogenetic abnormalities and also at relapse he revealed with imatinib-resistant E255K gene mutation, which is a common mutation that occurs frequently after imatinib therapy in Ph-positive ALL patients is the glutamic acid to lysine mutation at codon 255.

After the relapse the boy received high-dose chemotherapy and dasatinib and obtained complete molecular remission and restored full donor chimerism. There were no observed side effects of dasatinib treatment. The patient is now still in complete molecular remission and is continuing maintenance chemotherapy with dasatinib.

Thus, this case suggests that chemotherapy plus dasatinibcould be a treatment of choice for the children with relapsed Philadelphia chromosome positive acute lymphoblastic leukemia after allogeneic hematopoietic stem cell transplantation, which alsohas E255K gene mutation and various cytogenetic abnormalities.