In contrast to the well-established PARPi-resistance mechanisms based on restoration of BRCA1/2 pathway functions, we identify an adaptive mechanism driven by PGF-FLT1-AKT signaling that protects Brca1- and Bard1-deficient breast tumor cells from PARPi-induced cell death in-vivo. The gene discussed is BARD1; the disease is breast neoplasm.