We develop and analyze a four-species reaction-diffusion-advection model for normal tissue ($N$), tumor ($T$), immune effector cells ($I$), and chemotherapeutic drug ($U$). The model extends previous tumor--immune--drug frameworks by incorporating Allee effects in the $N$ and $T$ equations and allowing general second-order elliptic operators. Under minimal structural assumptions, we prove local well-posedness of weak solutions via the Schauder fixed-point theorem. A blow-up alternative then promotes local to global-in-time existence and uniqueness once $L^\infty$ bounds are established.
For spatiotemporal dynamics and treatment design, we employ a conservative Crank Nicolson/Backward Euler (CN-BE) scheme with homogeneous Neumann boundary conditions enforced via ghost points. Simulations on a heterogeneous two-dimensional tissue with three tumor peaks show that (i) without drug, tumors rapidly approach carrying capacity and form broad invasive fronts, while $I$ develops an annular band advancing inward toward tumor foci yet remains insufficient to halt tumor growth; and (ii) with chemotherapeutic treatment, pulsed dosing significantly suppresses tumor burden. For a fixed per-pulse input $V_0\tau$, varying amplitude $V_0$, duration $\tau$, and number of injections $N^*$ reveals dose-time-frequency trade-offs. The analysis provides a rigorous foundation for the model, and the simulations offer a practical tool for exploring chemotherapeutic scheduling in spatially heterogeneous tumors.
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Title
On a Mathematical Model Arising from an Optimal Chemotherapeutic Drug Treatment for Tumor Cells
Creators
Xiaoqin (Kurt) Liu
Contributors
Hong-Ming Yin (Advisor)
Tom Asaki (Committee Member)
Yuan Wang (Committee Member)
Awarding Institution
Washington State University
Academic Unit
Department of Mathematics and Statistics
Theses and Dissertations
Doctor of Philosophy (PhD), Washington State University