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. Author manuscript; available in PMC: 2022 Apr 12.
Published in final edited form as: Cancer Cell. 2021 Jan 14;39(4):466–479. doi: 10.1016/j.ccell.2020.12.008

Figure 1. Therapeutic index of cancer therapeutic agents.

Figure 1.

Therapeutic index (TI) is the ratio of the dose or exposure of a drug required to elicit the desired therapeutic effect (green arrow) compared with the dose or exposure at which toxicity becomes limiting (orange arrow). High-TI drugs (many successful targeted therapy drugs) are efficacious at well-tolerated doses; narrow-TI drugs (chemotherapies, some pan-essential gene inhibitors) often have high-efficacy doses slightly below doses leading to dose-limiting toxicities; the effective doses of inverted-TI drugs (some pan-essential gene inhibitors) are lower than doses that lead to severe toxicities, and these drugs often fail in clinical development.