Researchers at the University of Southern California have developed an exciting new approach to generate a renewable supply of genetically engineered immune cells, which could improve future cancer treatments. Their discovery tackles a major challenge in cell-based immunotherapy: producing enough functional cells and ensuring they remain active in the body for extended periods.
The new work, done by several USC Stem Cell researchers and published in Cell in June 2026, was centered on a type of immature cell in the blood called a granulocyte-monocyte progenitor (GMP). The GMPs would normally mature into macrophages or other immune cells that fight infections and activate other immune cells. The scientists discovered they could grow GMPs in the lab on a large scale while keeping their identity.
Macrophages are an integral part of the body’s own immune system. They move into tissue, consume dangerous cells and assist other immune cells to carry out their functions. Researchers have been investigating how to exploit these abilities in the fight against cancer.
Even so, there are a number of hurdles to overcome in manufacturing macrophages. They are hard to grow at scale outside the body and are a real challenge to manipulate, by genetic engineering, for example, and at the same time are prone to damage during freezing and storage.
Rather than creating mature macrophages, the USC team chose to target the cells from which they are derived, called progenitors. They formulated a cocktail of chemicals, which kept the GMPs’ ability to divide and become immune cells alive.
This method might offer a more adaptable starting place for scaled-up manufacturing of cellular therapies.
Then the researchers took the additional step of reprogramming the progenitor cells to make them more powerful fighters against cancer. They did that by adding another molecule to the cells: chimeric antigen receptors, or CARs, that help the cells identify markers on their targets.
They further modified the cells to make another immune-activating signal that could bring in and activate other immune cells, like tumour-killing T cells. This may give the treatment the ability to attack the cancer using more than one immune attack.
Potentially a significant advantage is the ability to manufacture an off-the-shelf therapy. Instead of having a bespoke approach where cells are manufactured from each individual patient, in the future the cells could be off-the-shelf, in advance, with manufactured batch cells being ready for use in a number of patients.
In the mouse study, the GMPS colonized bone marrow and other sites in the blood-rich tissues. From there, the GMPs produced a sustained stream of the engineered immune cells, including macrophages.
These experiments were carried out in animals with blood cancers and solid tumours. The CAR-modified cells showed the cells hold off disease progression and the dual receptor cells went on to show an even greater advantage in the experiments described. The team also demonstrated that their platform could be used to boost immunity against bacterial infections in mice with a hereditary immune disorder called chronic granulomatous disease.
This indicates the technology may have a use outside of cancer treatment, although additional work will need to be done before such a treatment could be adopted into medicine.
