Inclusion Criteria:

• At least 18 years of age

• Eastern Cooperative Oncology Group (ECOG) performance status score of ≤ 2

• Triple-negative breast cancer as determined by the treating oncologist

• Completed standard of care neoadjuvant chemotherapy in the opinion of their treating oncologist

• Patients whose tumors progress on neoadjuvant therapy may be enrolled

• No clinical evidence of local or distant recurrence

• Plan to receive standard of care adjuvant directed therapy

• Completed standard of care locoregional treatment, including definitive breast and lymph node surgery followed by standard radiation therapy, if recommended

• Residual cancer burden (RCB) index 2 or 3 as calculated per routine anatomic pathology clinical standards

• Absolute neutrophil count (ANC) ≥ 800/μL (within 30 days of first study vaccine administration)

• Hemoglobin (Hgb) ≥ 8 g/dL (within 30 days of first study vaccine administration)

• Platelets ≥ 75,000/ μL (within 30 days of first study vaccine administration)

• Total bilirubin ≤ 1.5 x institutional upper limit of normal (ULN), except patients with Gilbert's syndrome, in whom total bilirubin must be < 3.0 mg/dL (within 30 days of first study vaccine administration)

• Aspartate aminotransferase (AST)/alanine aminotransferase (ALT) ≤ 1.5 x institutional ULN (within 30 days of first study vaccine administration)

• Creatinine ≤ 1.5 x ULN mg/dL or creatinine clearance > 60 mL/min (within 30 days of first study vaccine administration)

• At least 28 days post systemic steroids prior to enrollment, unless used as part of prophylaxis to prevent intravenous (IV) contrast reactions.

  • Topical, ocular, intra-articular, intranasal, inhalational corticosteroids (with minimal systemic absorption) are allowed

• Must have recovered from major infections and/or surgical procedures; and in the opinion of the investigator, not have any significant active concurrent medical illnesses or condition precluding protocol treatment

• Patients of child-bearing potential must agree to use dual methods of contraception and have a negative urine pregnancy test at screening, and male patients must use an effective barrier method of contraception if sexually active with a person of child-bearing potential. Acceptable methods of contraception are abstinence, condoms with contraceptive foam, oral, implantable or injectable contraceptives, contraceptive patch, intrauterine device, diaphragm with spermicidal gel, or a sexual partner who is surgically sterilized or post-menopausal

Exclusion Criteria:

• Toxicities related to prior exposure to immune checkpoint inhibitors for which immune checkpoint inhibitors cannot be safely continued as determined by study investigator

• Germline BRCA1 or BRCA2 mutations with adjuvant olaparib planned within the study period

  • NOTE: If olaparib is not planned, then these patients are eligible

• Any known cardiac conditions:

  • Symptomatic restrictive cardiomyopathy
  • Dilated cardiomyopathy
  • Unstable angina within 4 months prior to enrollment
  • New York Heart Association functional class III-IV heart failure on active treatment
  • Symptomatic pericardial effusion

• Autoimmune disease requiring active systemic treatment

• Known hypersensitivity reaction to the GM-CSF adjuvant; any known contra-indication to GM-CSF

• Pregnant or breast feeding

• Known history of human immunodeficiency virus (HIV) infection, hepatitis B (e.g., hepatitis B virus surface antigen [HBsAg] reactive), or hepatitis C (e.g., hepatitis C virus [HCV] ribonucleic acid [RNA] is detected)

• Major surgery within the 4 weeks prior to initiation of first study vaccine

• Enrollment in any other clinical protocol or investigational trial that involves concurrent administration of experimental therapy and/or therapeutic devices, or investigational drug. Patients who completed prior clinical trials (such as neoadjuvant treatment, surgery or radiation trials) and are on long term follow up are permitted