Fig 1. Schematic overview of the model.

We developed a mathematical model to investigate the effects of changing mutation rates during treatment on the evolution of resistance. When treated with targeted or traditional cytotoxic chemotherapy, a sensitive cancer cell (left) might give rise to a resistant cell at a rate that increases with the drug dose administered (case 1), is independent of the dose (case 2), or decreases with the dose (case 3). For simplicity, we show linear relationships between drug dose and mutation rate; however, more complex relationships can easily be considered using our general framework.