A new technology that uses MR can track therapeutic immune cells that are injected into patients with colorectal cancer, according to a recent study published in the online journal Magnetic Resonance in Medicine.

Researchers at the University of California, San Diego School of Medicine, University of Pittsburgh and elsewhere used a perfluorocarbon (PFC) tracer with an MR technique that directly detects fluorine atoms in labeled cells.

Modified and labeled dendritic cells, which are potent stimulators of the immune system, were prepared from white blood cells and extracted from the patients.
Then those cells were injected into patients with stage four metastatic colorectal cancer in order to stimulate an anti-cancer T-cell immune response. The researchers evaluated how well the technique detects the labeled cells and monitors what happens to them and found that it worked well and that only half of the cells stayed at the inoculation site after 24 hours.

Eric T. Ahrens, first author of the study and professor at the University of California, San Diego, told DOTmed News that this new technology will make clinical trials more cost-effective. "These are very expensive trials and you would like to be able to maximize the amount of information that you get from each patient," he said.

In order to make the trials more cost-effective, it's "critically important" to know where the cells go after they are put into a patient's body because it determines whether they were delivered appropriately. Imaging can do that and it can also determine how the cells should be injected and what the course of the injection should be.

"These are critical questions but there are no standard tools currently that a clinician can use for a clinical trial or for the routine delivery of cells," said Ahrens. "This technology was developed to fill that urgent need."

He also believes the technology will help to lower regulatory barriers. The FDA wants to know where cells go once they are injected into a patient's body for safety reasons and this technique can provide them with answers.

The standard way for surgeons to get this information now is by conducting biopsies, but that's an invasive procedure that could lead to inconclusive results. "They can be inconclusive because they only sample tissue bites at a point or a cluster of points and you may miss the cells or give an inaccurate picture where they migrate," said Ahrens.

Additionally, sometimes longitudinal biopsies are conducted that occur over one or two weeks but that can be a burden for the patients and also very dangerous, according to Ahrens.

Going forward, Ahrens and the other researchers are going to evaluate the technology in a larger clinical trial to better define the uses of it. They also want to use different cell types such as emerging CAR T cell therapies, which have received a lot of attention lately, and could greatly benefit from this imaging technology.

There are also many stem cell trials where the effective delivery of cells is critical to success. "This technology could help determine whether the delivery is appropriate for the outcomes they'd like to achieve," said Ahrens.

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