Efficacy and safety of blinatumomab treatment in adult Korean patients with relapsed/refractory acute lymphoblastic leukemia on behalf of the Korean Society of Hematology ALL Working Party.

Blinatumomab, a bispecific T cell-engaging antibody, has demonstrated efficacy for relapsed or refractory acute lymphoblastic leukemia (ALL). In this study, we evaluated the efficacy and toxicity of blinatumomab in adult Korean patients with relapsed or refractory Philadelphia-negative B cell precursor ALL. A total of 50 patients received blinatumomab treatment between June 2016 and August 2017 in Korea. The median number of prior therapy was one (range, 1-4). Among the 49 evaluable patients, 22 (44.9%) achieved complete response (CR) or CR with incomplete blood count recovery, and 16 of whom subsequently underwent allogenic stem cell transplantation. Although no statistically significant differences were observed, patients with extramedullary disease and poor performance status had lower responses to blinatumomab treatment. In addition, the use of high-dose dexamethasone prior to blinatumomab treatment did not affect the response to blinatumomab. The median event-free survival and overall survival of the responders were 7.5 and 8.1 months, respectively. For non-hematologic toxicities, the most common toxicity was infection. The incidences of severe cytokine release syndrome and neurologic toxicity each was 4%. In conclusion, blinatumomab was an effective and tolerable therapy in adult Korean patients with relapsed or refractory Philadelphia-negative B cell precursor ALL.