Study of the Bria-IMT Regimen and CPI vs Physicians' Choice in Advanced Metastatic Breast Cancer.

This is a multicenter randomized, open label study to evaluate overall survival with the Bria-IMT regimen in combination with Checkpoint Inhibitor \[Retifanlimab\], versus Treatment of Patients'/Physicians' Choice (TPC) in advanced metastatic or locally recurrent breast cancer (aMBC) patients with no approved alternative therapies available. A secondary objective will be to evaluate the activity of the Bria-IMT regimen alone in comparison with the Bria-IMT regimen in combination with CPI. Initial randomization will be 1:1:1 to the Bria-IMT regimen + CPI (combination therapy), TPC, and the Bria-IMT regimen alone (monotherapy). After the first 150 patients have enrolled in the study, the monotherapy arm will be discontinued and patients allowed to cross over to the combination therapy if needed. Randomization will continue 1:1 between the combination therapy vs TPC. For the Bria regimen +/- CPI arms, treatment cycles occur every 3 weeks. TPC cycle details will be according to the site's SOC. In the absence of progressive disease or major safety issues, the patient will continue with therapy cycles, with imaging assessment every 6 weeks x2 then every 8 weeks thereafter. The Bria-IMT regimen includes: Day -2 or -3 Cyclophosphamide 300mg/m2 Day 0 SV-BR-1-GM given intradermally divided into 4 inoculations Day 1-3 CPI infusion plus interferon intra-dermally within each Bria-IMT inoculation site