Implantable devices made of a thin metallic mesh loaded with cancer-fighting immune cells are able to shrink inoperable ovarian tumors in mice, offering a potential way to boost the efficacy of cell therapies for ovarian cancer and other solid tumors, a study has found. The work is described in the report, "Nitinol thin films functionalized with CAR-T cells for the treatment of solid tumours," published in the journal Nature Biomedical Engineering. Solid tumors, including breast and ovarian cancers, employ multiple mechanisms to hide from and defend against the immune system. For that reason, cell therapies that proved effective against blood cancers have failed against solid tumors. Injected cancer-fighting immune cells are either unable to reach the tumor or to survive the hostile environment that surrounds it. Researchers at Fred Hutchinson Cancer Research Center may have taken an important step in circumventing this problem. Matthias Stephan, MD, PhD, and his team created a prototype of a medical device to be used in cell therapies for cancer. They crafted a very thin mesh — about seven times thinner than the width of a hair — made of nickel titanium, or nitinol, a metal that can be safely implanted in the body and has been used recently for building medical devices.