Disclosed herein are methods and kits used in treating a cancer characterized by aberrant activity of CSF3R. These methods involve detecting a mutation in exon 14 of CSF3R such as a mutation of T615 or T618 and treating the subject with a JAK inhibitor and/or detecting a mutation in exon 17 of CSF3R and treating with dasatinib or tyrosine kinase inhibitor with one or more targets in common with dasatinib.