Although we did not observe any impact of the incidence of grade 3-4 neutropenia or febrile neutropenia, the administration of late G-CSF after CAR-T infusion allowed reducing the duration of hospitalization without any impact on the toxicities, CRS or neurotoxicities, as well as on the efficacy of CAR-T in terms of response, examined by the outcome and on the CAR-T expansion. The gene discussed is CSF3; the disease is congenital rubella syndrome.