STEMVAC in Patients With Early Stage Triple Negative Breast Cancer

Inclusion Criteria: * Participants with triple negative breast cancer, stages IB, II or III. Estrogen receptor (ER)-negative and progesterone receptor (PR)-negative is defined as breast cancer with less than 10% of ER or PR expression. HER2 negative is defined as: * 0-1+ HER2 expression by immunohistochemistry (IHC) OR * Fluorescence in situ hybridization (FISH) negative OR * HER2 2+ and FISH negative * Note: Participants with low ER positivity (≤10%) who are already on adjuvant hormonal therapy will be allowed on study and can continue their adjuvant hormonal treatment during study participation. * Participants must have completed all standard of care (or investigational) systemic therapy (including immune modulating agents) and radiotherapy if used between 28 and 365 days prior to enrollment \* Note: Treatment with a bisphosphonate or denosumab to prevent bone loss is not considered to be systemic therapy for breast cancer and its use within the 28 day pre-enrollment period or while on study is not exclusionary. Treatment with adjuvant olaparib within the 28 day pre-enrollment period or while on study is not exclusionary. * Participants must agree to avoid systemic steroids for the duration of the treatment period and until completion of the 1 month post 2nd booster vaccine visit (end of treatment) * Participants must be at least 18 years of age \* Note: Because no dosing or adverse event (AE) data are currently available on the use of STEMVAC in participant…