The present disclosure is directed to a method of identifying a subject having chronic lymphocytic leukemia (CLL), non-Hodgkin's lymphoma (NHL), small lymphocytic lymphoma (SLL) or acute lymphoblastic leukemia (ALL) that is responsive to treatment with an anti-CD19 antibody, said method comprising: a) providing a blood sample obtained from said subject prior to treatment with said anti-CD19 antibody, b) determining the level of at least one biomarker in said sample selected from the group consisting of: i) peripheral NK cell count, and ii) CD16 expression levels on peripheral NK cells, c) comparing the level of said at least one biomarker in said sample to a predetermined cut off level, wherein levels of said at least one biomarker at or above the predetermined cut off level is indicative of a subject who would benefit from treatment with an anti-CD19 antibody. The present disclosure is also directed to a method for selecting a patient for treatment according to the above and to the use of an anti-CD19 antibody for the treatment of such a patient.La presente divulgación está dirigida a un método para identificar a un sujeto que tiene leucemia linfocítica crónica (CLL), linfoma no Hodgkin (NHL), linfoma linfocítico pequeño (SLL) o leucemia linfoblástica aguda (ALL) que responde a tratamiento con un anticuerpo anti-CD19, comprendiendo dicho método: a) proporcionar una muestra de sangre obtenida de dicho sujeto antes del tratamiento con dicho anticuerpo anti-CD19, b) determinar el nivel de al menos un biomarcador en dicha muestra seleccionada del grupo que consiste en i) recuento de células NK periféricas, y ii) niveles de expresión de CD16 en células NK periféricas, c) comparar el nivel de dicho al menos un biomarcador en dicha muestra a un nivel de corte predeterminado, en donde los niveles de dicho al menos un biomarcador en o por encima del nivel de corte predeterminado es indicativo de un sujeto que se beneficiaría del tratamiento con un anticuerpo anti-CD19. La p
