Physiologically-based pharmacokinetic model for CAR-T cells delivery and efficacy in solid tumors

Abnormal blood vessels limit the delivery and function of endogenous T cells as well as adoptively transferred Chimeric Antigen Receptor (CAR)-T cells in the tumor microenvironment (TME). We recently showed that vascular normalization using anti-VEGF therapy can overcome these challenges and improve the outcome of CAR-T therapy in glioblastoma models in mice. Here, we developed a physiologically based pharmacokinetic model to simulate the dynamics of both adoptively transferred CAR-T cells and endogenous immune cells in solid tumors following vascular normalization. Similar to our data, our model simulations show that vascular normalization reprograms the TME from immunosuppressive to immunosupportive—enhancing infiltration of endogenous CD8⁺ T cells and CAR-T cells, increasing M1 macrophages, and reducing M2 macrophages and regulatory T cells—thereby improving efficacy. Strikingly, vascular normalization reduces the number of infused CAR-T cells needed for tumor control by an order of magnitude. Moreover, synchronizing a second CAR-T infusion at their peak proliferative phase maximizes antitumor function. Furthermore, the efficacy of CAR-T cells engineered to secrete anti-VEGF antibody depends on the ability of CAR-T cells to induce vascular normalization. Additionally, combining vascular and stromal normalization can improve the efficacy of anti-VEGF antibody-producing FAP-CAR-T cells for the treatment of desmoplastic tumors such as pancreatic ductal adenocarcinoma. Finally, the model predicts that local CAR-T delivery can sustain high concentrations within the TME and induce recruitment of other antitumor immune cells, improving outcomes. Our model provides a versatile framework to optimize dosing strategies, treatment sequencing, and delivery routes for improving CAR-T therapies for solid tumors.

Significance Statement

Preclinical studies and early clinical trials of CAR-T therapy show encouraging responses in glioblastoma, diffuse midline gliomas, and neuroblastoma, yet substantial obstacles remain for effective CAR-T therapy for solid tumors. Building on our discovery that judicious VEGF blockade normalizes tumor vessels and enhances CD8⁺T-cell infiltration, we developed a mathematical model to optimize CAR-T therapy for solid tumors. Simulations predict that vascular normalization can render the TME immunosupportive and decrease CAR-T doses tenfold. In desmoplastic tumors, FAP-CAR-T efficacy is improved by combining anti-VEGF and stromal normalizing agents. Optimal scheduling and direct intratumoral delivery can mitigate T-cell exhaustion and improve tumor control further. Thus, our model serves as a strategic roadmap for optimal CAR-T deployment in solid tumors.