Inclusion Criteria:

          -  Women with histologically confirmed ER ≤ 10% and or PR ≤ 10% TNBC on the pre-trial
             metastatic biopsy.

          -  Age ≥ 18.

          -  ≤ 3 prior chemotherapies for metastatic disease.

          -  Prior immunotherapy is permitted and does not count as chemotherapy.

          -  The use denosumab or zoledronic is permitted.

          -  History of previously treated brain metastases with ≥ 4 weeks after definitive surgery
             and gamma knife/whole brain radiation and not taking steroids.

          -  ≥ 4 weeks from last oral or IV chemotherapy, small molecule inhibitor, a biologic
             agent, surgery or radiation.

          -  Performance status 0-2.

          -  Adequate organ and marrow function as defined below:

               -  leukocytes ≥ 3,000/mcL

               -  Absolute neutrophil count ≥ 1,000/mcL

               -  platelets ≥ 100,000/mcl

               -  total bilirubin within institutional upper limit of normal. (≤ ULN)

               -  AST (SGOT)/ALT (SPGT) ≤ 2 x ULN

               -  Creatinine ≤ ULN

               -  A negative serum or urine pregnancy test within 3 days of receiving Day 1 Cycle 1
                  of leflunomide.

          -  Women of child-bearing potential and men must agree to use adequate contraception
             before study entry, for the duration of study participation and for 90 days following
             completion of therapy. Should a woman become pregnant or suspect she is pregnant while
             participating in this study, she should inform her treating physician immediately.

          -  Recommended methods of birth control are: The consistent use of an approved hormonal
             contraception such as an intrauterine device (IUD), Double barrier methods (Diaphragm
             with spermicidal gel or condoms with contraceptive foam), Sexual abstinence (no sexual
             intercourse) or Sterilization. The use of hormonal forms of birth control is
             controversial in TNBC and as such women enrolled in the trial are permitted to use
             birth control pills or depot Provera, only after a documented discussion by the
             treating physician as too the uncertain risks of hormonal birth control methods in the
             TNBC population. A female of child-bearing potential is any woman (regardless of
             sexual orientation, having undergone a tubal ligation, or remaining celibate by
             choice) who meets the following criteria: Has not undergone a hysterectomy or
             bilateral oophorectomy; or Has not been naturally postmenopausal for at least 12
             consecutive months (i.e., has had menses at any time in the preceding 12 months).

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

        Exclusion Criteria:

          -  Patients who have had chemotherapy or radiotherapy within ≥ 2 weeks before entering
             the study or those who have not recovered from adverse events due to agents
             administered more than ≥ 4 weeks earlier.

          -  Patients may not be receiving any other investigational agents.

          -  The known history human immunodeficiency virus, acute and chronic Hepatitis B or C, or
             acute or previously treated tuberculosis.

          -  Patients with untreated brain metastases 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 leflunomide or teriflunomide.

          -  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.

          -  Patients must not be pregnant or nursing due to the potential for congenital
             abnormalities and the potential of this regimen to harm nursing infants.