UCSF team reprograms immune cells inside mice to fight cancer, study says

Researchers at UC San Francisco have developed a method that reprogrammed cancer-fighting immune cells inside the bodies of mice, according to work described in Nature and reported by ScienceDaily on 7 October 2026. The experiments used mice with humanized immune systems. ScienceDaily reported the work is the first time scientists have inserted a large stretch of DNA into a precise location in human T cells without first removing those cells from the body.

Standard CAR-T cell therapy requires doctors to collect a patient's immune cells and send them to a specialized facility, where the cells are genetically modified to recognize cancer, then shipped back and infused into the patient, according to ScienceDaily. The process can take weeks and cost hundreds of thousands of dollars. Seven CAR-T cell therapies are currently approved by the U.S. Food and Drug Administration for blood cancers, and they typically cost between $400,000 and $500,000, ScienceDaily reported. Patients generally must also receive intensive chemotherapy before the engineered cells are infused; ScienceDaily reported this treatment clears space in the bone marrow for the incoming cells but can be extremely taxing, particularly for older or medically frail patients.

Justin Eyquem, PhD, an associate professor of medicine at UCSF and the paper's senior author, said: 'It's become a global access issue; many patients who would benefit from CAR-T cells either can't afford them or can't get them fast enough.' He said there has been 'a big push in the field to try to move to directly producing these cells in the body.' Eyquem also said: 'I think this is just the beginning of a big wave of new therapies that will be truly transformational and save a lot of lives.'

Eyquem and collaborators from the Gladstone Institutes, Duke University and the Innovative Genomics Institute developed a system based on two different particles that together deliver CRISPR-Cas9 gene-editing machinery, according to ScienceDaily. ScienceDaily reported the targeted technique performed better than the conventional strategy of using viruses to insert DNA at random locations, and said the advance could have implications beyond CAR-T for cell and gene therapies more broadly. In the mouse experiments, the team used the method against aggressive leukemia, multiple myeloma and a solid tumor.

ScienceDaily reported that if the approach can be translated to people, it could remove much of the manufacturing, expense and delay that currently limits access to CAR-T therapy. It also reported that producing engineered immune cells directly inside the body, an approach known as in vivo manufacturing, could potentially remove the need for the preparatory chemotherapy.