ROR1⁺ LPC are resistant to induction therapy. Proportion of ROR1 positive cells (A-B) and number of binding sites (C-D) detected on samples at presentation (day 0), day 29, and wk 14 from BCP-ALL Pts 3, 12, and 17 (A,C) and T-ALL Pts 20 to 24 and 27 (B,D). Interrupted outlines indicate survival of ROR1⁺ LPC populations after induction therapy. Arrows indicate the emergence of ROR1⁺ in LPC. HSC, hematopoietic stem cell. Wk14, week 14.