Inclusion Criteria
1. Be ≥ 18 years of age.
2. Have signed informed consent.
3. Have histological confirmation of breast cancer with either locally recurrent unresectable
and/or metastatic lesions, and have failed prior therapy:
• Patients with persistent disease and local recurrence must not be amenable to local
treatment.
• For patients with metastatic disease, late-stage MBC with no meaningful alternative
therapies available and the following MBC class specific treatment histories:
a. Human epidermal growth factor 2 (HER2) positive must be previously treated
with at least 3 regimens containing at least two anti-HER2 and at least one
chemotherapy containing regimen.
b. Estrogen receptor (ER), progesterone receptor (PR) positive tumors: must be
refractory to hormonal therapy demonstrated by progression on at least 2
hormonal agents in 2 separate lines of hormone directed therapy.
c. Triple Negative tumors: Must have exhausted all curative intent therapies
including at least 2 prior chemotherapy regimens, which includes regimens in
neoadjuvant or adjuvant settings.
d. Cancers with known germline or genomic actionable targets, e.g. g/mBRCA,
must have been treated with all tumor directed indicated treatment e.g. PARPi,
if tolerated.
e. HER2 low patients, in addition to the appropriate therapies based on ER/PR
status and germline or genomic actionable targets, must also have received at
least one HER2-targeted agent approved for treatment of HER2 low patients.
f. HER2 negative tumors must be refractory to hormonal therapy (if indicated) and
previously treated with at least 2 chemotherapy regimens.
g. Patients with new or progressive breast cancer metastatic to the brain will be
eligible provided:
 The brain metastases must be clinically stable (without evidence of
progressive disease by imaging for at least 4 weeks prior to first dose)
 There is no need for steroids and patients have not had steroids for at least
2 weeks prior to the first dose
 If surgically debulked, must be healed with at least 3 weeks since surgery
prior to the first dose
4. Has expected survival of at least 4 months.
5. ECOG performance status of 0, 1 or 2
6. Patients who progressed while on adjuvant therapy or within 6 months of completing
adjuvant therapy may be deemed to have “failed” a line(s) systemic therapy for MBC,
albeit occult MBC, after discussion and approval of the medical monitor and sponsor.

Exclusion Criteria
1. Concurrent or recent chemotherapy, immunotherapy or major surgery within 21 days
prior to the first dose.
2. Radiotherapy within 14 days of the first dose of study treatment.
3. Toxicity of prior therapy that has not recovered to ≤ Grade 1 or baseline (with the
exception of any grade of alopecia or neuropathy and anemia not requiring transfusion
support).
4. Any toxicity to prior CPI that was grade 3 or higher unless it has been successfully
treated (e.g. hypothyroidism or hypopituitarism treated with replacement therapy).
5. Toxicity to prior CPI that has not resolved to grade 1 or less except for stable
asymptomatic endocrinopathies.
6. History of clinical hypersensitivity to the designated therapy as specified in the protocol,
including the proposed TPC, beef, or to any components used in the preparation of SV-
BR-1-GM.
7. History of hypersensitivity to any of the therapies proposed for treatment in this study.
8. Serum creatinine OR Measured OR calculated Creatinine Clearance (CrCl) (GFR can
also be used in place of creatinine or CrCl) >2.0 × ULN or with creatinine levels >2.0 × institutional ULN.
9. Absolute granulocyte or neutrophil count 10. Bilirubin ≥ 2 × ULN unless conjugated bilirubin ≤ ULN; alkaline phosphatase >5x upper
limit of normal (ULN); ALT/AST >3x ULN. For patients with hepatic metastases,
ALT/AST >5x ULN is exclusionary.
11. INR or PT or aPTT > 1.8 × ULN, unless the participant is receiving anticoagulant therapy
as long as PT or aPTT is within therapeutic range of intended use of anticoagulants.
12. Receiving any medication listed in the prohibited medication section of the protocol.
13. Proteinuria >2+ on urinalysis
14. A history or presence of an abnormal electrocardiogram (ECG) that, in the Investigator’s
opinion, is clinically meaningful. Screening corrected QT interval (QTc) interval >480
milliseconds is excluded (corrected by Fridericia or Bazett formula). In the event that a
single QTc is >480 milliseconds, the participant may enroll if the average QTc for the 3
ECGs is 15. New York Heart Association stage 3 or 4 cardiac disease.
16. A pericardial effusion of moderate severity or worse.
17. Symptomatic pleural effusion or ascites. A participant who is clinically stable following
treatment for these conditions (including therapeutic thoraco- or paracentesis) is eligible.
18. Any woman of childbearing potential (i.e., has had a menstrual cycle within the past year
and has not been surgically sterilized), unless she agrees to take appropriate precautions
to avoid becoming pregnant during the study and has a negative serum pregnancy test
within 7 days prior to starting treatment.
19. Men must have been sterile or, if they were potentially fertile/reproductively competent,
should take appropriate precautions to avoid fathering a child for the duration of the
study.
20. Women who are pregnant or nursing.
21. Known additional malignancy that is progressing or requires active treatment, or history
of other malignancy within 2 years of study entry with the exception of cured basal cell
or squamous cell carcinoma of the skin, superficial bladder cancer, prostate intraepithelial
neoplasm, carcinoma in situ of the cervix, or other noninvasive or indolent malignancy,
or cancers from which the participant has been disease-free for > 1 year, after treatment
with curative intent.
22. Patients who have uncontrolled HIV or have clinical or laboratory features indicative of
AIDS.
23. Have a diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy
(doses exceeding 10 mg daily of prednisone equivalent) or any other form of
immunosuppressive therapy within 7 days prior to the first dose of study treatment.
24. Have an active autoimmune disease that has required systemic treatment in past year (i.e.,
with use of disease modifying agents, corticosteroids, or immunosuppressive drugs).
Replacement therapy (e.g., thyroxine, insulin, or physiologic corticosteroid replacement
therapy for adrenal or pituitary insufficiency, etc.) is allowed.
25. Known active HAV, HBV, or HCV infection, as defined by elevated transaminases with
the following serology: positivity for HAV IgM antibody, anti-HCV, anti-HBc IgG or
IgM, or HBsAg (in the absence of prior immunization).
26. Active infections requiring systemic therapy within the past 14 days.
27. Patients with severe psychiatric disease (e.g., schizophrenia, bipolar, or borderline
personality disorder) or other clinically progressive major medical problems, unless
approved by the Investigator in consultation with the Medical Monitor.
28. Has received a live vaccine within 28 days of the first dose of study drug.
29. Patients may not be on a concurrent clinical trial, unless approved by the Investigator.