After concluding that the brain tumor was due to metastatic disease progression and not a new primary CNS malignancy, the patient underwent radiation therapy to the cerebellar cavity and was started on subsequent systemic therapy for metastatic RMC using sacituzumab monotherapy with granulocyte colony stimulating factor (G-CSF) support resulting in improvement of pain control as well as increased general activity level. Here, CSF3 is linked to brain neoplasm.