In the event of severe neutropenia—defined as grade 3 febrile neutropenia, grade ≥ 4 neutropenia lasting less than one week, or grade ≥ 3 neutropenia resulting in treatment delay—it is recommended that the dose of SG is reduced by 25% and that secondary prophylaxis with G-CSF is initiated [33]. This evidence concerns the gene CSF3 and Decreased total neutrophil count.