Efficacy and safety of tisagenlecleucel in Japanese pediatric and young adult patients with relapsed/refractory B cell acute lymphoblastic leukemia

Tisagenlecleucel is an autologous T cell genetically modified ex vivo using a lentiviral vector encoding an anti-CD19 chimeric antigen receptor. Here, we present the efficacy and safety of tisagenlecleucel in a subgroup of Japanese patients with relapsed/refractory (r/r) B-cell acute lymphoblastic leukemia (ALL). ELIANA was a single-arm, open-label, multicenter, phase 2 study. Patients were aged ≥ 3 years at screening to ≤ 21 years at the time of diagnosis, and had ≥ 5% lymphoblasts in bone marrow at screening. Primary endpoint was overall remission rate [ORR; complete remission (CR) + CR with incomplete blood recovery (CRi)] within 3 months after infusion. As of April 13, 2018, eight patients were enrolled and six had been infused. ORR was 66.7% (95% confidence interval 22.3–95.7); three patients achieved CR and one patient had CRi. All patients with CR/CRi were negative for minimal residual disease. One patient had CR/CRi lasting 19.5 + months. Cytokine release syndrome (CRS) and neurological events occurred in 83% and 17% of patients, respectively. CRS resolved with anti-cytokine therapy and supportive care. Two deaths occurred due to disease progression. No cases of cerebral edema were observed. Tisagenlecleucel produced high remission rates and durable responses offering a new treatment option for Japanese pediatric and young adults with r/r B-ALL.