New Injectable Gel Can Deliver Immune Cells Directly to Cancer Tumors

Elizabeth Millard

April 14, 2022

A simple, two-ingredient gel may boost the fighting power of a groundbreaking cancer treatment, say Stanford University engineers.

The gel ― made from water and a plant-based polymer – delivers targeted T cells adjacent to a cancer growth, taking aim at solid tumors.

It's the latest development in CAR T-cell therapy, a type of immunotherapy that involves collecting the patient's T cells, reengineering them to be stronger, and returning them to the patient's body.

Results have been promising in blood cancers, such as leukemia and lymphoma, but less so in solid tumors, such as brain, breast, or kidney cancer, according to the National Cancer Institute.

The gel "is a really exciting step forward," says Abigail Grosskopf, a PhD candidate who is the lead study author, "because it can change the delivery of these cells and expand this kind of treatment to other cancers."

CAR T-Cell Therapy: Limits in Solid Tumors

Currently available CAR T-cell therapies are administered by intravenous infusion. But that doesn't do much against tumors in specific locations because the cells enter the bloodstream and flow throughout the body. The cancer-fighting effort exhausts the T cells, weakening their ability to infiltrate dense tumors.

CAR T cells need cytokines to tell them when to attack, Grosskopf explains. If delivered through an IV drip, the number of cytokines required to destroy a solid tumor would be toxic to other, healthy parts of the body.

So Grosskopf and her colleagues created a hydrogel that can temporarily hold the T cells and cytokines and that can be injected near a tumor, bombarding the cancerous growth.

In their study, which was published in Science Advances, the injections wiped out mouse tumors in 12 days. The gel degraded harmlessly a few weeks later.

A "Leaky Pen" That Fights Cancer

The reason a gel works better than a liquid is because of its staying power, says Grosskopf, who compares the method to a leaky pen.

The gel acts as the "pen," releasing activated CAR T cells at regular intervals to attack the cancerous growth. Whereas liquid dissipates quickly, the gel's structure is strong enough to stay in place for weeks, Grosskopf says. Plus, it's biocompatible and harmless within the body, she adds.

More preclinical studies are needed before human clinical trials can occur, Grosskopf says.

"Not only could this be a way to deliver T cells and cytokines," Grosskopf says, "but it may be used for other targeted therapy cancer drugs that are in development. So we see this as running parallel to those efforts."

Taking an even broader view, the gel could have applications across medical specialties, such as slow-release delivery of vaccines.

Sci Adv. Published online April 8, 2022. Full text

Elizabeth Millard is a freelance journalist specializing in health, medicine, and fitness.

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