A method for risk-stratifying subjects suffering from B-precursor acute lymphoblastic leukemia, said subjects are intended for a therapy which comprises re-directing of T-cells against target cells, wherein said therapy includes a bispecific antibody comprising a CD3 binding domain or a genetically engineered T-cell having a chimeric antigen receptor, comprising (a) determining the amount of blast cells in a bone marrow sample from said subject; and/or determining the number of blast cells per 1 μl in a CSF sample from said subject, (b) risk-stratifying said subjects into one of the following categories: (i) subjects having an amount of at least 20% blast cells per 200 counted bone marrow cells in a bone marrow sample from said subjects; (ii) subjects having 5 blast cells or less per 1 μl in a CSF sample from said subjects; (iii) subjects having an amount of about less than 20% blast cells per 200 counted bone marrow cells in a bone marrow sample from said subjects, while said subjects having 5 or less blast cells per 1 μl in a CSF sample from said subjects; (iv) subjects having an amount of about less than 20% blast cells per 200 counted bone marrow cells in a bone marrow sample from said subjects; (v) subjects having more than 5 blast cells per 1 μl in a CSF sample from said subjects; or (vi) subjects having an amount of about less than 20% blast cells per 200 counted bone marrow cells in a bone marrow sample from said subjects, while said subjects having more than 5 blast cells per 1 μl in a CSF sample from said subjects, wherein the risk-stratification allows for the prediction as to whether or not a subject will develop a potential adverse neurological reaction or for mitigation of a potential adverse neurological reaction. (a) determining the amount of blast cells in a bone marrow sample from said subject; and/or determining the number of blast cells per 1 μl in a CSF sample from said subject, (b) risk-stratifying said subjects into one of the following categories: (i) subjects having an amount of at least 20% blast cells per 200 counted bone marrow cells in a bone marrow sample from said subjects; (ii) subjects having 5 blast cells or less per 1 μl in a CSF sample from said subjects; (iii) subjects having an amount of about less than 20% blast cells per 200 counted bone marrow cells in a bone marrow sample from said subjects, while said subjects having 5 or less blast cells per 1 μl in a CSF sample from said subjects; (iv) subjects having an amount of about less than 20% blast cells per 200 counted bone marrow cells in a bone marrow sample from said subjects; (v) subjects having more than 5 blast cells per 1 μl in a CSF sample from said subjects; or (vi) subjects having an amount of about less than 20% blast cells per 200 counted bone marrow cells in a bone marrow sample from said subjects, while said subjects having more than 5 blast cells per 1 μl in a CSF sample from said subjects, wherein the risk-stratification allows for the prediction as to whether or not a subject will develop a potential adverse neurological reaction or for mitigation of a potential adverse neurological reaction. (i) subjects having an amount of at least 20% blast cells per 200 counted bone marrow cells in a bone marrow sample from said subjects; (ii) subjects having 5 blast cells or less per 1 μl in a CSF sample from said subjects; (iii) subjects having an amount of about less than 20% blast cells per 200 counted bone marrow cells in a bone marrow sample from said subjects, while said subjects having 5 or less blast cells per 1 μl in a CSF sample from said subjects; (iv) subjects having an amount of about less than 20% blast cells per 200 counted bone marrow cells in a bone marrow sample from said subjects; (v) subjects having more than 5 blast cells per 1 μl in a CSF sample from said subjects; or (vi) subjects having an amount of about less than 20% blast cells per 200 counted bone marrow cells in a bone marrow sample from said subjects, while said subjects having more than 5 blast cells per 1 μl in a CSF sample from said subjects,