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Updated: Dec 3, 2025
Stereotactic Adoptive Transfer of Cytotoxic Immune Cells in Murine Models of Orthotopic Human Glioblastoma Multiforme Xenografts
Published on: September 1, 2018
Human macrophages engineered to secrete a bispecific T cell engager support antigen-dependent T cell responses to
Jennifer L Gardell1, Lisa R Matsumoto1, Harrison Chinn1
1Ben Towne Center for Childhood Cancer Research, Seattle Children's Research Institute, Seattle, Washington, USA.
Background:
Targeted and effective treatment options are needed for solid tumors, including glioblastoma (GBM), where survival rates with standard treatments are typically less than 2 years from diagnosis. Solid tumors pose many barriers to immunotherapies, including therapy half-life and persistence, tumor penetrance, and targeting. Therapeutics delivered systemically may not traffic to the tumor site. If cellular therapies or drugs are able to access the tumor site, or can be delivered directly within the tumor, treatments may not persist for the duration necessary to reduce or eliminate tumor burden. An approach that allows durable and titratable local therapeutic protein delivery could improve antitumor efficacy while minimizing toxicities or unwanted on-target, off-tissue effects.
Methods:
In this study, human monocyte-derived macrophages were genetically engineered to secrete a bispecific T cell engager (BiTE) specific to the mutated epidermal growth factor variant III (EGFRvIII) expressed by some GBM tumors. We investigated the ability of lentivirally modified macrophages to secrete a functional BiTE that can bind target tumor antigen and activate T cells. Secreted BiTE protein was assayed in a range of T cell functional assays in vitro and in subcutaneous and intracranial GBM xenograft models. Finally, we tested genetically engineered macrophages (GEMs) secreting BiTE and the proinflammatory cytokine interleukin (IL)-12 to amplify T cell responses in vitro and in vivo.
Results:
Transduced human macrophages secreted a lentivirally encoded functional EGFRvIII-targeted BiTE protein capable of inducing T cell activation, proliferation, degranulation, and killing of antigen-specific tumor cells. Furthermore, BiTE secreting macrophages reduced early tumor burden in both subcutaneous and intracranial mouse models of GBM, a response which was enhanced using macrophages that were dual transduced to secrete both the BiTE protein and single chain IL-12, preventing tumor growth in an aggressive GBM model.
Conclusions:
The ability of macrophages to infiltrate and persist in solid tumor tissue could overcome many of the obstacles associated with systemic delivery of immunotherapies. We have found that human GEMs can locally and constitutively express one or more therapeutic proteins, which may help recruit T cells and transform the immunosuppressive tumor microenvironment to better support antitumor immunity.
Insights
Genetically engineered macrophages secreting a bispecific T cell engager (BiTE) targeting EGFRvIII effectively reduced glioblastoma tumor burden. Dual-engineered macrophages secreting BiTE and IL-12 further enhanced this antitumor response in preclinical models.
Area of Science:
- Immunology
- Oncology
- Biotechnology
Background:
- Solid tumors, including glioblastoma (GBM), present significant challenges for immunotherapy due to barriers like short drug half-life, poor tumor penetration, and systemic toxicity.
- Developing localized and sustained delivery of therapeutic proteins is crucial for improving antitumor efficacy and minimizing off-target effects in solid tumors.
Purpose of the Study:
- To engineer human macrophages to secrete a bispecific T cell engager (BiTE) targeting the mutated epidermal growth factor variant III (EGFRvIII) found in some GBM tumors.
- To evaluate the efficacy of these engineered macrophages in activating T cells and reducing tumor burden in preclinical GBM models.
Main Methods:
- Human monocyte-derived macrophages were genetically modified using lentiviral vectors to secrete an EGFRvIII-specific BiTE.
- The functionality of the secreted BiTE was assessed through various in vitro T cell assays.
- The therapeutic potential was tested in subcutaneous and intracranial GBM xenograft mouse models, including evaluation of dual-engineered macrophages secreting BiTE and IL-12.
Main Results:
- Genetically engineered macrophages successfully secreted functional BiTEs that induced T cell activation, proliferation, degranulation, and tumor cell killing.
- Macrophages secreting BiTE demonstrated a reduction in early tumor burden in both subcutaneous and intracranial GBM models.
- Dual-engineered macrophages secreting both BiTE and IL-12 showed enhanced tumor growth inhibition in an aggressive GBM model.
Conclusions:
- Genetically engineered macrophages (GEMs) can overcome immunotherapy delivery challenges by infiltrating and persisting within solid tumors.
- GEMs provide a platform for local, sustained expression of therapeutic proteins, potentially recruiting T cells and converting the immunosuppressive tumor microenvironment to support antitumor immunity.
