Do you pursue testing for ERBB2 mutations in patients with metastatic breast cancer who are clinically HER2-negative by IHC and FISH?

I generally will consider NGS in women with progressive TNBC or progressive ER positive, Her2 negative MBC that has progressed through at least 3-4 hormonal therapies and/or chemotherapies. I find that about 5-10% of these women have mutations in the tyrosine kinase domain of Her2 (a bit higher than...