Bria-IMT Whole-Cell Vaccine plus PD-1 Blockade Extends Median OS to 13.4 mo in Heavily Pretreated HR+/HER2- mBC

Bria-IMT combines irradiated HER2/GM-CSF–secreting allogeneic breast-cancer cells with low-dose cyclophosphamide, peg-IFN-α, and pembrolizumab/retifanlimab; 54 metastatic-breast-cancer patients (median 6 prior lines) were enrolled in the phase I/II trial (NCT03328026). Grade ≥3 treatment-related AEs were uncommon (13%, mostly diarrhea, PE, lipase rise). The phase-3 formulation without IFN-γ incubation (n=37) yielded median OS 13.4 mo vs 6.9 mo for the earlier lot, median PFS 3.6 mo vs 2.6 mo (P 0.01), ORR 9.5%, and clinical-benefit rate 55%. Survival correlated with immune pharmacodynamic markers: patients showing a vaccine-induced delayed-type-hypersensitivity response had OS 11.9 mo vs 5.5 mo, and those with post-dose CTC < 5 had OS 13.4 mo vs 5.5 mo. These outcomes compare favorably with physician’s-choice ET or chemo where median OS is ~8–10 mo after CDK4/6 failure.

https://aacrjournals.org/clincancerres/article/31/12_Supplement/PS3-04/754031/Abstract-PS3-04-Overall-Survival-Results-of-Bria