Hypothetical kinetics of tumor load in CLL patients who received 3 or 6 courses of FCR. Patients remaining MRD positive after treatment have a high likelihood of relapse (red arrows), whereas only 1 relapse was observed in MRD-negative patients (green and blue arrows). Three additional courses of FCR for patients who attained MRD negativity after the first 3 courses of FCR might be inefficacious (broken blue line) or might induce an additional reduction in tumor load (dotted blue line) that will translate into a clinical benefit with longer follow-up (FU designates current follow-up). The open arrow symbolizes the sensitivity of clinical staging. The figure is not to scale. See Figure 3A in the article by Strati et al that begins on page 3727.