Question: The figure below is adapted from the "ZUMA-1" clinical trial for CD19 CAR T cells. Let's imagine this trial was conducted with two treatment groups: one receiving CD19 CAR T cells and the other receiving bispecific CD19/CD20 CAR T cells (in green). A. Regardless of treatment group, many patients relapse within the first three months. Come up with THREE possible explanations for why the majority of those who relapse do so within a very short time-frame. Your answers can refer to either treatment group I. II. III. B. Of the patients who did NOT respond to the bispecific CAR T cell therapy, none had cancer cells negative for both CD20 and CD19 (ie none of their cancer cells are double negative aka CD19-/CD20-). Do you find this unusual? Why, or why not?