Inclusion Criteria:

- Patients must have histologically or cytologically confirmed breast cancer that is
metastatic or if the disease is locally advanced and unresectable, then the standard
curative measures are no longer effective.

- Must have received no more than 3 prior cytotoxic therapies in the metastatic
setting. If patients demonstrated positive Her2/Neu disease they must have progressed
on Herceptin.

- Eastern Cooperative Oncology Group (ECOG) performance status ≤2 (Karnofsky >60%

- Patients must have normal organ and marrow function as defined below:

- leukocytes ≥3,000/µL

- absolute neutrophil count ≥1,500/µL

- platelets ≥100,000/µL

- total bilirubin within normal institutional limits

- aspartic transaminase (AST)/alanine transaminase (ALT) ≤2.5 X institutional upper
limit of normal

- creatinine within normal institutional limits

- OR - creatinine clearance ≥60 mL/min/1.73 m^2 for patients with creatinine levels
above institutional normal

- Must have measurable disease by Response Evaluation Criteria in Solid Tumors (RECIST)
with one exception. However, may have bone only disease if an x-ray modality shows at
least 1 cm of tumor.

- Female patient of childbearing potential has a negative serum pregnancy test beta
human chorionic gonadotropin(β-hCG) and agree to use effective contraception during
the study.

- Women of child-bearing potential and men must agree to use adequate contraception
(hormonal or barrier method of birth control; abstinence) for the duration of study
participation. Should a woman become pregnant or suspect she is pregnant while
participating in this study, she should inform her treating physician immediately.

- Ability to understand and the willingness to sign a written informed consent document

Exclusion Criteria:

- Patients who have had chemotherapy or radiotherapy within 2 weeks prior to entering
the study or those who have not recovered from adverse events due to agents
administered more than 2 weeks earlier. If the patient has residual toxicity from
prior therapy should be ≤ grade 1.

- Patients currently participating or has participated in a study with an
investigational compound or device within 30 days of Day 1 of the study

- Patient has known active central nervous system (CNS) metastases or carcinomatous
meningitis. Patients who have completed a course of therapy would be eligible for
study if they are stable for 2 months prior to entry with no evidence of new or
enlarging CNS metastasis and are off chronic steroids.

- History of allergic reactions attributed to compounds of similar chemical or biologic
composition to eribulin mesylate or carboplatin

- Patients on Class Ia and III antiarrhythmics. The principal investigator (PI) and/or
treating physician will evaluate the medications to make sure none would
significantly interfere with corrected QT interval (QTc).

- Patient has known history of Hepatitis B or C or active Hepatitis A or HIV

- Uncontrolled intercurrent illness including, but not limited to ongoing or active
infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac
arrhythmia, or psychiatric illness/social situations that would limit compliance with
study requirements. This includes symptomatic pleural effusions or ascites.

- Because there is an unknown but potential risk for adverse events in nursing infants
secondary to treatment of the mother with eribulin and carboplatin, breastfeeding
should be discontinued if the mother is treated with eribulin and carboplatin.

- Peripheral neuropathy of severity greater than 1 as a baseline