Tianze Guo

Cell-based immunotherapy, for example, chimeric antigen receptor T (CAR-T) cell immunotherapy, has revolutionized cancer treatment, particularly for blood cancers. However, factors such as insufficient T cell tracking, tumour heterogeneity, inhibitory tumour microenvironment (TME) and T cell exhaustion limit the broad application of CAR-based immunotherapy for solid tumours. In particular, the TME is a complex and evolving entity, which is composed of cells of different types (e.g., cancer cells, immune cells and stromal cells), vasculature, soluble factors and extracellular matrix (ECM), with each component playing a critical role in CAR-T immunotherapy. Thus, developing approaches to mitigate the inhibitory TME factors is critical for future success in applying CAR-T cells for solid tumour treatment. Accordingly, understanding the bilateral interaction of CAR-T cells with the TME is in pressing need to pave the way for more efficient therapeutics. In the following review, we will discuss TME-associated aspects with an emphasis on T cell trafficking, ECM barriers, abnormal vasculature, solid tumour heterogenicity and immune suppressive microenvironment. We will then summarize current engineering strategies to overcome the challenges posed by the TME-associated factors. Lastly, the future directions for engineering efficient CAR-T cells for solid tumour therapy will be discussed.

Glioblastoma (GBM) presents a significant therapeutic challenge due to the limited efficacy of existing treatments. Chimeric antigen receptor (CAR) T-cell therapy offers promise, but its potential in solid tumors like GBM is undermined by the physical barrier posed by the extracellular matrix (ECM). To address the inadequacies of traditional 2D cell culture, animal models, and Matrigel-based 3D culture in mimicking the mechanical characteristics of tumor tissues, we employed biomaterials and digital light processing-based 3D bioprinting to fabricate biomimetic tumor models with finely tunable ECM stiffness independent of ECM composition. Our results demonstrated that increased material stiffness markedly impeded CAR-T cell penetration and tumor cell cytotoxicity in GBM models. The 3D bioprinted models enabled us to examine the influence of ECM stiffness on CAR-T cell therapy effectiveness, providing a clinically pertinent evaluation tool for CAR-T cell development in stiff solid tumors. Furthermore, we developed an innovative heat-inducible CAR-T cell therapy, effectively overcoming the challenges posed by the stiff tumor microenvironment.

Cancer metabolism plays an essential role in therapeutic resistance, where significant inter- and intra-tumoral heterogeneity exists. Hypoxia is a prominent driver of metabolic rewiring behaviors and drug responses. Recapitulating the hypoxic landscape in the tumor microenvironment thus offers unique insights into heterogeneity in metabolic rewiring and therapeutic responses, to inform better treatment strategies. There remains a lack of scalable tools that can readily interface with imaging platforms and resolve the heterogeneous behaviors in hypoxia-associated metabolic rewiring. Here we present a micro-metabolic rewiring (μMeRe) assay that provides the scalability and resolution needed to characterize the metabolic rewiring behaviors of different cancer cells in the context of hypoxic solid tumors. Our assay generates hypoxia through cellular metabolism without external gas controls, enabling the characterization of cell-specific intrinsic ability to drive hypoxia and undergo metabolic rewiring. We further developed quantitative metrics that measure the metabolic plasticity through phenotypes and gene expression. As a proof-of-concept, we evaluated the efficacy of a metabolism-targeting strategy in mitigating hypoxia- and metabolic rewiring-induced chemotherapeutic resistance. Our study and the scalable platform thus lay the foundation for designing more effective cancer treatments tailored toward specific metabolic rewiring behaviors. • An assay is established to measure cancer-specific response to an oxygen-limited TME. • Cancer cells possess distinct capability in driving a hypoxic TME and undergo rewiring. • Cancer-specific HIF response traits underlie distinct metabolic rewiring behaviors. • Mitochondrial complex inhibition is especially effective against cells driving severe hypoxia.