FLT1 and breast cancer: Since axitinib is already FDA-approved for metastatic renal-cell carcinoma (Tyler, 2012) and is currently being tested in combination with talazoparib in a Phase Ib/II clinical trial (NCT04337970) in renal cancer, our findings provide the rationale for repurposing this combination treatment in breast cancer patients with mutations in BRCA1/2 or PALB2. Moreover, if PGF-FLT1 signaling is increased in PARPi-resistant human breast cancers, future studies may validate the use of anti-PGF antibodies as another opportunity for therapeutic intervention to overcome PARPi resistance.