Next, PARPi-resistant Brca1-def and Bard1-def tumor cells, transduced with either control lentivirus (“Lenti-Con”), Flt1i lentivirus, or Flt1i lentivirus plus Flt1 o/e lentivirus, were injected orthotopically in the mammary glands of syngeneic B6/129F1 mice. The gene discussed is FLT1; the disease is neoplasm.