The significant number of nanotherapeutic options as well as heterogeneity within and amongst tumor microenvironments (TME) make cancer drug development an ongoing challenge. Mathematical modelling may provide a basis by which cancer therapeutics can be evaluated at scale and, longer term, in a personalized manner. Recently, a 3D continuum model was developed that simulates tumor growth and associated interactions with the TME, including vasculature, extracellular matrix remodeling, and tumor growth factors. However, to reach applicability in cutting-edge nanotherapeutics, this model required significantly decreased computation times and simulation of macrophages that are involved in the delivery of a novel nanotherapeutic for breast cancer liver metastases (BCLM). In this talk, we describe how this model is “suited for battle” for simulating a macrophage-mediated nanotherapy against multiple BCLM within an in silico mouse liver lobe. This seminar will cover how computation times of a Multigrid solver are being improved through parallel processing without sacrificing simulation resolution, how macrophages and their interactions in the TME can be represented mathematically in a continuum model, and how hundreds of BCLM representing conditions in vivo were simulated simultaneously in silico to evaluate therapeutic response. Finally, future considerations of mathematical modelling of immune species in cancer will be discussed.