Among 19 BCBM pts with at least twice tumor assessment, the overall ORR was 78.9% (95% CI: 54.4–93.9) and iORR was 73.7% (95% CI: 48.8–90.9), DCR was 100%. In addition, 6 pts completed first tumor assessment and 5 achieved PR and 1 had SD...Encouraging efficacy and tolerability was observed for ZN-1041 monotherapy or combined with capecitabine and trastuzumab in TKI naïve, HER2+ BCBM patients.