Penn State University’s Breakthrough: Blue Light-Activated Immune Cells Effectively Penetrate Solid Tumors

Immunotherapies that mobilize a patient’s own immune system to fight cancer have become a treatment pillar. These therapies, including CAR T-cell therapy, have performed well in cancers like leukemias and lymphomas, but the results have been less promising in solid tumors.

A team led by researchers from the Penn State College of Medicine has re-engineered immune cells so that they can penetrate and kill solid tumors grown in the lab. They created a light-activated switch that controls protein function associated with cell structure and shape and incorporated it into natural killer cells, a type of immune cell that fights infections and tumors. When these cells are exposed to blue light, they morph and can then migrate into tumor spheroids — 3D tumors grown in the lab from either mouse or human cell lines — and kill tumor cells. This novel approach could improve cell-based immunotherapies, the researchers said.

The findings were published today (Oct 23) in the Proceedings of the National Academy of Sciences. The researchers also filed a provisional application to patent the technology described in the paper.

“This technology is totally out of the box. It’s akin to CAR T-cell therapy, but here, the guiding principle is the ability of cells to infiltrate the tumor,” said senior author Nikolay Dokholyan, G. Thomas Passananti Professor at the Penn State College of Medicine and professor of biochemistry and molecular biology. “I don’t know of another approach that is anything close to this.”

CAR T-cell therapy was first approved by the Food and Drug Administration in 2017, and since then, it has demonstrated encouraging results for some cancers, particularly blood cancers. T-cells, a white blood cell in the immune system, are removed from a patient and re-engineered to produce a protein on their surface that binds to a specific target protein on cancer cells. When the CAR T-cells are infused back into the patient, they kill cancer cells with that target protein.

However, CAR T-cell therapy is less successful for treating solid tumors, which make up approximately 90% of adult human cancers and 40% of childhood cancers, Dokholyan said. Immune cells can’t infiltrate the dense network of proteins and other cells surrounding the tumor, and the hostile environment inhibits their tumor-fighting abilities. Plus, tremendous diversity among solid tumors makes it difficult to home in on a specific target protein to attack. To improve cell-based immunotherapies for solid tumors, Dokholyan said immune cells need to be able to bypass the solid tumor’s defenses.

Using computation modeling, the team designed and tested a light-controlled version of septin-7, an internal protein essential for maintaining a cell’s cytoskeleton — the structure that maintains cellular shape and organization. They inserted a light-sensitive domain into septin-7 to create what Dokholyan called “an allosteric regulator.” The light-sensitive portion of the protein is located far from the protein’s active site and doesn’t interfere with the structure and function of the protein until it’s triggered. The domain is activated by blue light, which switches the protein function on and off.