Researchers at USC say they have found a way to multiply granulocyte-monocyte progenitors (GMPs) in a controlled laboratory culture, keep those cells renewing, and genetically program them to attack tumors. In mice, the engineered cells settled in bone marrow, generated new immune cells and slowed both blood cancers and solid tumors. The work is promising, but it is not yet a human treatment or an approved off-the-shelf product.
What USC’s scientists discovered
Granulocyte-monocyte progenitors are immature blood-forming cells that normally develop into macrophages and related immune cells. The USC Stem Cell team reports that GMPs can be expanded extensively in a defined culture while retaining their identity and their ability to produce functional immune cells.
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The finding challenges a long-standing assumption in blood biology: durable self-renewal was generally associated with hematopoietic stem cells, not with more developmentally committed progenitors. In the USC experiments, GMPs continued dividing under controlled conditions without losing the ability to generate their expected immune-cell descendants.
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That combination—large-scale expansion plus preserved function—could provide a renewable starting population for cellular immunotherapy. Instead of repeatedly collecting mature immune cells for each manufacturing run, developers could potentially maintain a bank of engineered progenitors and use them to produce therapeutic cells as needed.
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How the proposed cell platform works
- Expand the progenitors. GMPs are maintained in a defined laboratory culture designed to support long-term self-renewal while preserving their developmental identity.
- Add anti-cancer programming. The researchers genetically engineered the cells, including chimeric antigen receptor (CAR) designs intended to recognize cancer-associated markers.
- Enhance immune coordination. Additional signaling was incorporated to help recruit or activate other immune cells, rather than relying only on direct tumor-cell killing.
- Test the cells in animals. Engineered GMPs were introduced into mice to determine whether they could establish themselves in bone marrow, generate new immune cells and affect tumor growth.
The approach is different from making a single batch of mature effector cells. It aims to create a self-renewing progenitor population that can continue supplying immune cells after administration.
What the mouse experiments showed
In the reported mouse studies, the engineered cells established themselves in bone marrow and produced new immune cells. Tumor growth slowed in models of both blood cancers and solid tumors.
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Those results demonstrate biological activity in animals, not clinical benefit in people. The reports do not provide patient numbers, response rates, survival statistics or a human safety profile. They also do not show that the cells can avoid every possible immune or tumor-related failure in a patient.
| Evidence question | What has been reported | What remains unestablished |
|---|---|---|
| Can GMPs be multiplied? | They were expanded extensively in a defined laboratory culture while retaining their identity. | The exact clinical manufacturing scale, cost and release specifications have not been reported for a patient product. |
| Do engineered cells persist? | In mice, the cells established in bone marrow and continued producing immune cells. | Persistence, dosing and durability in humans are unknown. |
| Do they affect tumors? | Mouse models showed slower progression of blood cancers and solid tumors. | No human efficacy or survival result has been reported. |
| Is there a treatment available? | No clinical treatment or regulatory approval is described. | Human trials and a patient-access pathway have not been established. |
What “GMP cells” means here
In this study, GMP means granulocyte-monocyte progenitor, a type of immature blood-cell progenitor. It is not the same acronym as Good Manufacturing Practice, the quality system used to produce medicines.
A future therapy would need both meanings to be addressed: the biological GMP progenitors would have to be made under Good Manufacturing Practice conditions, with validated identity, purity, potency, sterility and genetic-quality controls. The USC reports describe a defined research culture, but they do not establish that a finished clinical product has already met those manufacturing requirements.
Could this become an off-the-shelf cancer treatment?
Potentially, the platform is aimed at making an “off-the-shelf” model more practical because a renewable progenitor population could be expanded, engineered and stored before a patient needs treatment. That is a manufacturing concept, not a current product claim.
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Several development questions remain open. Researchers would need to show that engineered cells behave consistently from batch to batch, remain controllable after transplantation, reach tumors at useful levels and avoid dangerous immune reactions or unintended effects. Clinical studies would also have to establish an appropriate dose, schedule and patient population. None of those human-development milestones is reported yet.
How this differs from conventional mature-cell therapies
The central distinction is the starting cell. Conventional cellular therapies commonly begin with mature immune cells that are collected, engineered and expanded for administration. The USC platform begins with a progenitor that is intended to renew itself and continually generate immune-cell descendants.
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| Comparison axis | USC GMP platform | Mature-cell therapy comparison |
|---|---|---|
| Starting cell | Granulocyte-monocyte progenitor | Mature immune cell; the specific product determines the cell type |
| Expansion concept | Long-term self-renewal in a defined culture | Expansion of a manufactured batch; durable self-renewal is not the defining premise |
| Engineering target | CAR recognition plus signals intended to recruit or activate other immune cells | Depends on the therapy and its engineered construct |
| Testing reported here | Blood-cancer and solid-tumor mouse models | Not evaluated by this USC study |
| Clinical stage | Preclinical animal research | Varies by product; no human result is supplied for this platform |
The comparison does not show that one approach is superior. It explains why the USC work could matter: self-renewing progenitors may address supply and persistence challenges, while the actual clinical advantages still need to be demonstrated.
Study publication and commercial development
The findings appear in the 2026 paper “Expansion and CAR engineering of granulocyte-monocyte progenitors for cellular immunotherapy,” published in Cell (DOI: 10.1016/j.cell.2026.05.043).
USC says Qi-Long Ying, Shi Yue, Xueyuan A. Jing, Zheng Guo, Ravindra Majeti, Chao Zhang, Tai Nguyen and Jiaqi Tang are co-inventors on patents related to the work. USC reports that those patents were licensed to Myelogene Inc. A license documents an intellectual-property relationship; it does not mean a marketed therapy, an approved clinical trial or a way for patients to purchase the cells.
Ying described the work as “a scalable and engineerable GMP platform for cellular immunotherapy” with possible implications for cancer immunotherapy and stem-cell biology. The team also mentions potential applications in infectious disease, but those uses remain research possibilities rather than established treatments.
What happens next
The next meaningful test is translation into carefully monitored human studies. Before that, developers must define a clinical manufacturing process, verify the engineered cells’ safety and potency, and obtain regulatory authorization for trials. Until such studies report results, the strongest defensible conclusion is limited: USC has demonstrated a renewable, engineerable GMP progenitor platform in laboratory systems and mice, not a proven cancer cure.
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