Chimeric antigen receptor (CAR) T cells are engineered immune cells designed to recognize and eliminate antigen-presenting cancer cells. CAR T-cell therapy has currently shown substantial clinical success in treating B-cell malignancies, particularly in hematologic cancers. For on B-cell lymphomas, several mathematical models have been developed to describe the local interactions between CAR T cells and malignant B cells at the tumor site [1, 2]. However, these models often fail to capture the systemic dynamics of CAR T-cell trafficking, especially in compartments beyond the tumor, such as peripheral blood. In this context, physiologically based pharmacokinetic (PBPK) modeling provides a powerful framework for simulating the systemic distribution of therapeutic agents using whole-body compartmental models that capture trafficking between organs [3, 4]. We developed an extended PBPK model for CAR T cells in humans, incorporating specific interactions with lymphoma B cells within lymph nodes. To model tumor engagement, we employed an enhanced version of the interaction framework proposed in [1], which accounts for both cellular proliferation and tumor-induced immunosuppression. Through scenario-based simulations, we explored the dynamics of CAR T-cell behavior and identified key parameter sensitivities. These findings enhance our understanding of CAR T-cell distribution and efficacy across anatomical compartments and provide a basis for optimizing treatment strategies. By bridging localized tumor models with systemic PBPK frameworks, our model provides a comprehensive platform for investigating CAR T-cell therapies in B-cell lymphomas. Moreover, its ability to incorporate clinical data, such as blood-derived cell counts, highlights its potential for supporting personalized treatment planning through simulation-guided approaches.