Heparanase-loaded CAR T EVs remodel colorectal tumor ECM and boost T cell immunity, extending survival.
Background
Chimeric antigen receptor (CAR) T cell therapy holds significant promise for cancer treatment, but its efficacy in solid tumors is severely hampered by the dense extracellular matrix (ECM) surrounding tumor cells. This physical barrier prevents CAR T cells from effectively infiltrating the tumor microenvironment (TME) and reaching their targets. Additionally, the immunosuppressive nature of the TME further limits T cell persistence and function, necessitating novel strategies to overcome these critical obstacles and improve therapeutic outcomes in challenging cancers like colorectal cancer.
Study Design
Researchers engineered mesothelin-targeted CAR T cells to express heparanase (HPSE) fused to a truncated hepatitis A virus pX domain (pX-Δ1-30), enabling surface display of HPSE on extracellular vesicles (EVs). They compared these HPSE-pX-Δ1-30 CAR T cells against standard CAR T cells in 2D and 3D colorectal cancer models to assess ECM penetration and tumor killing. The study also evaluated EV properties, T cell modulation, and in vivo efficacy in HCT116 xenograft models, monitoring intratumoral infiltration, tumor burden, and survival.
Results
HPSE-pX-Δ1-30 CAR T cells demonstrated significantly enhanced ECM penetration, performing nearly fourfold more effectively than standard CAR T cells. These engineered cells also exhibited increased expression of pro-apoptotic ligands, including TNF-related apoptosis-inducing ligand (TRAIL), Fas ligand (FasL), and perforin, leading to stronger tumor killing in both 2D and 3D colorectal cancer models. The derived extracellular vesicles (EVs) retained CAR and chemokine receptors (CCR5/CCR7) and apoptotic ligands, facilitating efficient uptake by both tumor and T cells. EV exposure promoted T cell proliferation, CCR5 expression, and the formation of central/stem-like memory T cells, while notably reducing PD-1 and CD57 expression. In HCT116 xenografts, HPSE CAR T cells showed increased intratumoral infiltration. EVs from these cells further promoted host T cell infiltration.
Treatment with HPSE CAR T cells significantly reduced tumor burden and extended survival beyond 70 days, without causing systemic toxicity.
Key Findings
- HPSE-pX-Δ1-30 CAR T cells penetrated ECM mimics nearly fourfold more effectively than standard CAR T cells.
- Engineered CAR T cells expressed more
TRAIL,FasL, andperforin, enhancing tumor killing. - CAR T-derived EVs promoted T cell proliferation,
CCR5expression, and central/stem-like memory formation. - EVs lowered
PD-1andCD57expression on T cells, indicating reduced exhaustion. - In xenografts, HPSE CAR T cells reduced tumor burden and extended survival beyond 70 days without systemic toxicity.
Why It Matters
This research introduces a compelling dual strategy that directly addresses two major hurdles in solid tumor CAR T therapy: the physical ECM barrier and the immunosuppressive TME. By engineering CAR T cells to locally degrade ECM via heparanase-loaded EVs and simultaneously modulate host T cell immunity, this approach could significantly improve CAR T cell infiltration and persistence. The localized, pH-dependent ECM degradation mechanism minimizes systemic exposure to heparanase, potentially enhancing safety. This translational strategy offers a promising path toward more effective CAR T cell therapies for challenging solid tumors like colorectal cancer, moving closer to a clinical protocol that could enhance patient responses and survival.
car t cell
colorectal cancer
tumor microenvironment
ecm remodeling
heparanase
immunotherapy