Yes—researchers have reported ways to program immune cells inside the body to attack cancer, including by giving T cells or macrophages instructions to recognize tumors. The leading examples described in recent studies are still preclinical: they produced results in mouse models, not proof that the methods are safe or effective cancer treatments for people.
What does “reprogramming immune cells inside the body” mean?
It means delivering genetic instructions or gene-editing tools to immune cells while they are still inside the body, rather than collecting the cells, modifying them in a laboratory, and returning them to the patient. Researchers are investigating this approach to make cells acquire cancer-fighting functions, such as expressing a chimeric antigen receptor (CAR), which helps a cell recognize a chosen target.
In conventional CAR-T treatment, a patient’s T cells are collected, modified and expanded outside the body, then infused back into the patient. In-body approaches aim to deliver the programming machinery directly to immune cells and could reduce some individualized manufacturing steps. That potential simplification does not make an experimental delivery platform an approved or proven treatment.
How do the experimental approaches differ?
These studies do not describe one interchangeable technology. They target different immune cells and use different delivery vehicles and genetic payloads. Some deliver mRNA, which can produce temporary CAR expression; another combines gene-editing machinery and a DNA donor to insert a CAR gene at a selected location.
#1 Best Overall
| Approach | Target and delivery | Programming strategy | Reported evidence |
|---|---|---|---|
| Site-specific T-cell engineering | T cells; enveloped delivery vehicles (EDVs) carrying CRISPR–Cas9 ribonucleoproteins, together with an adeno-associated virus (AAV) donor | Attempts to insert a CAR gene at the T-cell receptor alpha constant (TRAC) locus, rather than relying on transient mRNA expression | The 18 March 2026 Nature paper reports CAR-T generation and tumor control in several humanized mouse models. This is a proof of concept, not a clinical result. |
| Polymer-lipid mRNA delivery | T cells; an arginine-modified oligoethylenimine-based lipid nanoparticle called ERTLNP | Delivers CAR-encoding mRNA. The authors describe ligand-free delivery, T-cell activation and preferential transfection in the spleen after systemic administration. | The 2026 Nature Materials study reports in-vivo CAR-T generation and activity in cancer and fibrosis models. A 29 September 2026 Nature Reviews Materials highlight discusses the delivery challenge and notes that many LNP formulations preferentially target the liver. |
| CAR-macrophage programming in the abdominal cavity | Macrophages; intraperitoneal delivery of CAR-encoding mRNA in lipid nanoparticles | Programs macrophages, not T cells, with a CAR payload that can be expressed from mRNA. | A Nature Communications paper published 24 December 2025 reports mouse cancer-model findings, changes in tumor immune activity and examination of combination treatment with PD-1 blockade. |
| Alveolar macrophage engineering | Alveolar macrophages in the lungs; liposomal nanomedicine | In-situ engineering of macrophages in a lung-cancer model. | A 2026 Nature Communications study reports antitumor activity in a lung-cancer mouse model. It also describes editing efficiency as suboptimal and says long-term safety needs evaluation before clinical trials. |
| CD8-targeted mRNA delivery | Circulating T cells; CD8-targeted mRNA lipid nanoparticles | Delivers mRNA to reprogram T cells, a distinct method from targeted DNA insertion at TRAC. | A 2026 Molecular Therapy paper reports tumor-growth inhibition in a humanized Nalm6 mouse model. |
Why use mRNA in some approaches and gene insertion in another?
mRNA delivery
mRNA gives a cell instructions to make a protein, such as a CAR, without the same kind of targeted genomic insertion described in the TRAC study. Its expression can be transient. That may limit how long the programmed function lasts, so adequate delivery and duration matter. The ERTLNP work is one attempt to address the difficulty of delivering mRNA to T cells; its reported findings remain preclinical.
Targeted DNA insertion
The 2026 Nature study paired CRISPR–Cas9 editing machinery with an AAV DNA donor to target CAR insertion at the TRAC locus. The aim is more controlled, potentially durable expression. In return, editing and insertion make precise targeting and long-term safety important questions; delivering the machinery to unintended cells could also cause problems.
Rank #2
- Cancer Immunotherapy Principles and Practice
- ABIS BOOK
- Demos Medical Publishing
What have the studies shown—and what have they not shown?
The reported tumor effects come from animal models, including humanized mouse models, not from evidence that patients treated with these in-body methods live longer, respond to treatment, or avoid serious side effects. The 2026 lung-cancer macrophage study reports nearly 90% tumor inhibition in an orthotopic mouse model; that figure is a result in that model, not a human response rate and not directly comparable with results from other experiments.
The evidence is also specific to each platform. For example, results from CAR-macrophage delivery do not establish that a T-cell platform works, and success in one mouse tumor model does not establish effectiveness against other cancers or in people. The cited studies describe experimental methods, not generally available treatments. A March 2026 Nature paper stated that seven CAR-T therapies had FDA approval at the time of publication; that figure referred to established CAR-T therapies then, not to approval of the newer in-body platforms.
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- Selective delivery: The programming tools must reach enough of the intended immune cells without engineering unrelated cells. Off-target delivery could create safety or efficacy problems.
- Efficiency: A method may not program enough target cells to produce the intended effect. The alveolar-macrophage study explicitly describes its editing efficiency as suboptimal.
- How long the effect lasts: mRNA expression can be temporary, while genomic insertion aims for more persistent expression and brings distinct editing and insertion-safety questions.
- Long-term safety: The mouse-model results do not settle the risks of unintended cell modification, gene editing or durable CAR expression in people. The alveolar-macrophage researchers specifically say long-term safety needs evaluation before clinical trials.
- Translation to patients: Animal-model activity is an early step. The cited findings do not establish human benefit or clinical safety for these specific platforms.
Can someone receive or try these treatments now?
The studies described here are preclinical reports, not evidence that these platforms are available cancer treatments. The cited material does not establish a current human-trial or regulatory status for each specific newer approach. These delivery systems use specialized genetic payloads and are not something to reproduce with consumer gene-editing kits or lab equipment.
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