Figure 2.

Elimination of tumor cells by targeting both proliferative and quiescent cancer cell populations. Situation (A) describes the current clinical obstacle in the treatment of solid tumors due to the existence of quiescent cancer cells, which are insensitive to cell-cycle-active drugs (Figure 1). Situation (B) describes an ideal outcome by targeting both proliferative and quiescent cancer cell populations. Briefly, proliferative cancer cells could be targeted by cell-cycle-dependent anticancer reagents and quiescent cancer cells could be removed by small-molecule drugs or immunotherapies developed from strategy 3. Situation (C) describes a feasible strategy. In brief, targeting both proliferative and quiescent cancer cell populations has a better chance of removing a larger proportion of tumor cells compared to Situation A. During the drug-free period, residual tumors will regrow, but fewer latent cells could result in smaller regrowth tumors. Re-expanded tumors can be re-treated by targeting both proliferating and quiescent cancer cell populations. This strategy could be able to delay the onset of drug resistance and tumor recurrence, thereby prolonging survival expectations.