ROR1 and breast cancer: In summary, we have shown in a cohort of almost 1000 high-risk early-stage breast cancer patients treated on the I-SPY2 platform that pretreatment expression of ROR1 was higher in HR- HER2- subtype, did not correlate with pCR, and was associated with worse EFS in HR + HER2- patients with high post-treatment residual cancer burden (RCB-II/III).