Inclusion Criteria:

1.Females at least 18 years of age 2 Diagnosis of metastatic breast cancer 3.ECOG Score of
0-2 4.Treating oncologist has decided to initiate any new systemic therapy with emphasis
on recruiting patients commencing a taxane-based regimen. Taxine-based therapy may be
docetaxel or paclitaxel, and it can be given on any schedule,including weekly or every 3
weeks. Other treatment can include non-taxane chemotherapy or trastuzumab-with or without
other therapy.

5.Patient is willing to return for one or more additional ~18 mL blood draw (s) at 24-48-,
and /or 72 hours and ~3-4 weeks after the initiation of therapy.At a minimum, patients
must donate blood at baseline, one intermediate interval (24, 48, 72 hr) and at ~3-4 weeks
6.Signed Informed Consent Form

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Exclusion Criteria:

Patient is unable and unwilling to provide a blood specimen at a minimum of one of the
intermediate blood draw time points at 24, 48, or 72 hours -