Hence, prior use of blinatumomab (irrespective of the response) in our opinion is not considered an absolute contraindication for the use of tisagenlecleucel, however the CD19 status of the relapsed/refractory B-ALL (flow cytometry on bone marrow sample) should be considered in the decision to prescribe tisagenlecleucel, as the impact on remission durability amongst those with pre-treatment blinatumomab is not firmly established. This evidence concerns the gene CD19 and precursor B-cell acute lymphoblastic leukemia.