%0 Clinical Trial, Phase I
%T Phase 1b/2 study of blinatumomab in Japanese adults with relapsed/refractory acute lymphoblastic leukemia.
%A Kiyoi H
%A Morris JD
%A Oh I
%A Maeda Y
%A Minami H
%A Miyamoto T
%A Sakura T
%A Iida H
%A Tuglus CA
%A Chen Y
%A Dos Santos C
%A Kalabus J
%A Anderson A
%A Hata T
%A Nakashima Y
%A Kobayashi Y
%J Cancer Sci
%V 111
%N 4
%D Apr 2020
%M 31971321
%F 6.518
%R 10.1111/cas.14322
%X Adult patients with relapsed/refractory (R/R) B-precursor acute lymphoblastic leukemia (ALL) have a poor prognosis. Blinatumomab is a bispecific T-cell engager (BiTE) immuno-oncology therapy with dual specificity for CD19 and CD3 that redirects patients' CD3-positive cytotoxic T cells to lyse malignant and normal B cells. We conducted an open-label, phase 1b/2 study to determine the safety, pharmacokinetics, efficacy and recommended dose of blinatumomab in Japanese adults with R/R B-precursor ALL. Patients received 9 μg/day blinatumomab during week 1 and 28 μg/day during weeks 2-4, with a 2-week treatment-free interval (6-week cycle); patients received 28 μg/day blinatumomab in subsequent cycles. Primary endpoints were the incidence of dose-limiting toxicities (DLT) in phase 1b and complete remission (CR)/CR with partial hematologic recovery (CRh) within the first two cycles in phase 2. A total of 26 patients enrolled and 25 (96%) reported grade ≥3 adverse events (mostly cytopenias). There were no DLT. CR/CRh within two cycles was achieved by 4 of 5 patients (80%) in phase 1b and 8 of 21 patients (38%) in phase 2. Among patients with evaluable minimal residual disease, 4 (100%) in phase 1b and 3 (38%) in phase 2 had a complete MRD response. Median RFS for 8 patients who achieved CR/CRh in phase 2 was 5 (95% CI: 3.5-6.4) months; median OS was not estimable. There were no significant associations between maximum cytokine levels or percentage of specific cell types during cycle 1 and response. Consistent with global studies, blinatumomab appeared to be safe and efficacious in Japanese adults with R/R ALL.