FIG 1.

Simplified evolutionary dynamics during intermittent therapy. For the full mathematical model and computer simulations, see the study by Zhang et al.¹¹ Green cells are sensitive to treatment, and red cells are resistant. The top panel demonstrates intermittent therapy that begins with a prolonged induction period. This excessively reduces the frequency of resistant cells at the expense of sensitive ones, rendering the subsequent drug-off period less effective in restoring sensitivity. In the lower panel, we demonstrate that these dynamics can be avoided by using on/off cycles from the start of therapy.