Injection Reprograms Tumour Immune Cells into Cancer Fighters Instantly

A drug injected directly into the tumour is absorbed by macrophages, prompting them to recognise and attack cancer cells while activating nearby immune defences.

This eliminates the need for lab-based cell extraction and modification. In animal models, the strategy significantly slowed tumour growth and sparked strong anticancer immune responses.

KAIST (President Kwang Hyung Lee) announced that a research team led by Professor Ji-Ho Park from the Department of Bio and Brain Engineering has developed a new treatment approach.

When a drug is injected directly into a tumour, macrophages already present in the body absorb the drug and begin producing CAR (a cancer-recognising device) proteins. This process converts them into anticancer immune cells known as "CAR-macrophages."

Why Solid Tumours Are So Hard to Treat

Solid tumours, including gastric, lung, and liver cancers, form dense structures that block immune cells from entering or functioning effectively because of this physical and biological barrier, many existing immune cell therapies struggle to work well against these types of cancers.

CAR-macrophages have emerged as a promising next-generation immunotherapy. Unlike some immune cells, macrophages can directly engulf and destroy cancer cells. They also stimulate nearby immune cells, helping to amplify the body's overall anticancer response.

Despite their potential, current CAR-macrophage therapies rely on extracting immune cells from a patient's blood, growing them in the lab, and genetically modifying them before reinfusion. This process is slow, expensive, and difficult to scale, which limits its practicality for many patients.

Reprogramming Immune Cells Directly Inside the Body

To bypass these challenges, the KAIST team focused on "tumour-associated macrophages" that naturally gather around tumours. The researchers developed a method to reprogram these cells directly inside the body rather than modifying them outside it.

Their approach uses lipid nanoparticles -- engineered to be easily taken up by macrophages -- loaded with both mRNA that carries cancer-recognition instructions and an immune-activating compound.

As described by the researchers, this method creates CAR-macrophages by "directly converting the body's own macrophages into anticancer cell therapies inside the body."

Strong Tumour Suppression in Animal Studies

When the treatment was injected into tumours, macrophages quickly absorbed the nanoparticles and began producing proteins that identify cancer cells.

At the same time, immune signalling was activated. The resulting "enhanced CAR-macrophages" showed much stronger cancer-killing ability and stimulated surrounding immune cells, leading to a powerful anticancer response.

In animal models of melanoma (the most dangerous form of skin cancer), tumour growth was significantly reduced. The researchers also found evidence that the immune response could extend beyond the treated tumour, suggesting the potential for broader, body-wide immune protection.

A New Direction for Cancer Immunotherapy

Professor Ji-Ho Park said, "This study presents a new concept of immune cell therapy that generates anticancer immune cells directly inside the patient's body." He added that "it is particularly meaningful in that it simultaneously overcomes the key limitations of existing CAR-macrophage therapies -- delivery efficiency and the immunosuppressive tumour environment."

Study Details and Funding

The study was led by Jun-Hee Han, PhD, from the Department of Bio and Brain Engineering at KAIST as the first author. The findings were published on November 18 in ACS Nano, an international journal focused on nanotechnology.

The research was supported by the Mid-Career Researcher Program of the National Research Foundation of Korea.

- ANI