This study is for people with advanced or recurrent breast cancer that doesn't have any approved treatments available. It will test a new treatment plan called the Bria-IMT regimen, both alone and with a drug called Retifanlimab, compared to what a doctor usually chooses. The Bria-IMT regimen includes a drug called Cyclophosphamide and another drug, SV-BR-1-GM, given through the skin. The Checkpoint Inhibitor (CPI) Retifanlimab is given through a vein.

• Duration: Treatment cycles are every 3 weeks, with check-ups every 6 to 8 weeks.
• Eligibility: Must be 18 or older with confirmed breast cancer and no other treatment options.
• Considerations: Cannot participate if you received certain therapies or had major surgery recently.

Participants will be randomly placed into one of the study groups. If the Bria-IMT regimen alone doesn't work, they can switch to the combination therapy. The study will check if the new treatment helps patients live longer.