Biomarker analysis revealed that the breast cancer gene 2, BMP/Retinoic Acid Inducible Neural Specific 3, F-box/WD repeat-containing protein 7, tyrosine-protein kinase KIT and retinoblastoma 1 abnormalities led to shorter PFS, while ctDNA negative at baseline or clearance at 2 cycles of treatment was associated with longer PFS (18.1 vs. 4.3 months). Here, RB1 is linked to breast cancer.