Effects of Intratumoral Competition on Allowable Treatment Breaks under Immune-Mediated Tumor Control

In this study, we investigated the effects of intratumoral competition and intermittent immunotherapy on tumor population dynamics using numerical simulations. We focused on how the immune-mediated elimination rate of the dominant tumor subtype, together with the duration of treatment withdrawal jointly determine treatment outcomes. Our results demonstrate that achieving an optimal balance between reducing the population of stronger cancer cells and preventing the regrowth of weaker cancer cells is essential for effective tumor suppression. Both the immune-mediated elimination efficiency and the length of treatment withdrawal critically determine the maximum allowable treatment break that maintains the total tumor burden below a control threshold. We further show that higher competition ratios significantly shrink the optimal regions for immune response. These findings provide quantitative insights into the design of intermittent treatment strategies that enhance innate immune effectiveness while maintaining tumor control.