Eribulin in Angiosarcoma and Epithelioid Hemangioendothelioma (EHE)

Inclusion Criteria: * Metastatic or locally advanced angiosarcoma, treated with at least one prior systemic therapy where no standard of care curable therapy is available OR metastatic or locally advanced malignant and progressive epithelioid hemangioendothelioma (EHE). * A maximum of 5 EHE patients will be accrued on this study * Archival tissue confirming the diagnosis must be reviewed by BWH/DFCI/MGH pathology. * Progression on at least one prior systemic therapy or progression during an observation phase of no anti-cancer therapy within the prior 3 months; prior taxanes are allowed * Participants must have measurable disease by RECIST 1.1, defined as at least one lesion that can be accurately measured in at least one dimension (longest diameter to be recorded for non-nodal lesions and short axis for nodal lesions) as ≥20 mm with conventional techniques or as ≥10 mm with spiral CT scan, MRI, or calipers by clinical exam. * Age \> 18 years. * ECOG performance status ≤2 * Life expectancy of greater than 3 months * Participants must have normal organ and marrow function as defined below: * leukocytes ≥3,000/mcL * absolute neutrophil count ≥1,000/mcL * platelets ≥100,000/mcL * total bilirubin within normal institutional limits * AST(SGOT)/ALT(SGPT) ≤2.5 × institutional upper limit of normal * creatinine clearance ≥50 mL/min/1.73 m2 for participants with creatinine levels above institutional normal. * Baseline QTcF \< grade 2 * The effects of Eribulin on the developing human fetus are unknown. For this reason and because of the risk of teratogenicity, women of child-bearing potential must agree to use adequate contraception prior to study entry and for the duration of study participation, and 4 months after completion of Eribulin administration. Should a woman become pregnant or suspect she is pregnant while she or her partner is participating in this study, she should inform her treating physician immediately. Men treated or enrolled on this protocol must also agree to use adequate contraception prior to the study, for the duration of study participation, and 4 months after completion of Eribulin administration. * Willingness to undergo serial tumor biopsies before and on treatment. * Ability to understand and the willingness to sign a written informed consent document. Exclusion Criteria: * Participants who have had chemotherapy or radiotherapy within 3 weeks (6 weeks for nitrosoureas or mitomycin C), immunotherapy within 3 weeks, targeted therapies (e.g. small molecule inhibitors such as pazopanib) within 2 weeks prior to entering the study or those who have not recovered from adverse events due to agents administered more than 4 weeks earlier. Not clinically significant or clinically stable adverse events from prior therapy (e.g. immunotherapy related hypothyroidism or insulin-dependent diabetes stable on medication or TKI-related hypertension or rash etc.) is allowed. * Participants who are receiving any other investigational agents. * Participants with known brain metastases and/or leptomeningeal disease should be excluded from this clinical trial because of their poor prognosis and because they often develop progressive neurologic dysfunction that would confound the evaluation of neurologic and other adverse events. * History of allergic reactions attributed to compounds of similar chemical or biologic composition to eribulin. * Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure (NYHA Class II), unstable angina pectoris or myocardial infarction within 6 months of enrolment, serious or life-threatening cardiac arrhythmia, subjects with a high probability of Long QT syndrome or QTcF prolongation of \> 501 mcsec (grade 2) on at least two separate ECG following correction of any electrolyte imbalance or psychiatric illness/social situations that would limit compliance with study requirements. * Females who are breastfeeding or pregnant at Screening or Baseline (as documented by a positive beta-human chorionic gonadotropin \[ß-hCG\] (or human chorionic gonadotropin \[hCG\]) test with a minimum sensitivity of 25 IU/L or equivalent units of ß-hCG \[or hCG\]). A separate baseline assessment is required if a negative screening pregnancy test was obtained more than 72 hours before the first dose of study drug. * HIV-positive participants on combination antiretroviral therapy are ineligible because of the potential for pharmacokinetic interactions with Eribulin. In addition, these participants are at increased risk of lethal infections when treated with marrow-suppressive therapy. Appropriate studies will be undertaken in participants receiving combination antiretroviral therapy when indicated