Use of PRO Onc Assay to Assess HER2 in Patients With Metastatic Breast Cancer

Patients with HER2-negative metastatic breast cancer will be identified, and blood specimens will be obtained from each participant. The PRO Onc Assay will be performed on CTCs isolated from these specimens. When clinically indicated, fine needle aspiration biopsy will also be obtained and submitted for the PRO Onc Assay.

8 mg/kg IV loading dose, followed by 6 mg /kg IV every 3 weeks until progressive disease or unacceptable toxicity with evaluations performed every 8 weeks

840 mg IV loading dose, followed by 420 IV every 3 weeks until progressive disease or unacceptable toxicity with evaluations performed every 8 weeks