Spontaneously regressed CLL tumors express weak surface CD49d but retain high levels of Bcl-2. FACS analysis of the gated CLL population of PBMCs. The gated CLL population was analyzed for (A) basal Erk and Akt phosphorylation and (B) cell-surface LAIR1 expression. Spontaneous regression cases (REG; n = 14) from the regression time point (T1) were compared against indolent (INDOL) M-CLL (n = 35) and UM-CLL (n = 4) cases. Basal Erk and Akt phosphorylation in CLL cells was normalized to B cells from 3 age-matched healthy donors, and expressed as fold change compared with these controls. CLL expression of (C) ROR1, (D) CD38, (E) CD62L, and (F) CD49d on spontaneous regression cases (REG, n = 17) from the regression time point (T1) compared with indolent (INDOL; n = 54) and progressive (PROG; n = 40) cases. (G) Expression of CD49d and CD38 was compared between sequential diagnostic (T0) and regression (T1) time points in individual spontaneous regression cases. The gated CLL population was analyzed for the expression of (H) FasR, (I) Bcl-2, and (J) Mcl-1. For all comparisons except Mcl-1, 17 spontaneous regression cases (REG) from the regression time point (T1) were compared against 54 indolent (INDOL) and 40 progressive (PROG) CLL cases. For Mcl-1, 11 spontaneous regression cases from the regression time point (T1) were compared against 20 indolent and 29 progressive cases. In panels A to F and H to J, complete and partial spontaneous regression are represented by red and blue dots, respectively. Statistical significance is indicated by *P < .05, **P < .01, ***P < .001, and ****P < .0001. In panel G, each colored line represents a specific case and 5% expression is indicated (- - -). ns, comparisons that are not statistically significant.