Stanford Scientists 'Supercharge' Immune Cells to Attack Solid Tumors

Stanford Medicine researchers have found a way to make natural killer cells, immune cells that can recognize and destroy abnormal cells, more effective against solid tumors. In a study on mice published last month in the journal Science Translational Medicine, the enhanced cells infiltrated tumors and slowed their growth, senior author John Sunwoo and colleagues reported.

Immune therapies have worked well against blood cancers, but solid tumors behave like fortified strongholds that keep immune cells out and blunt the ones that get in. The Stanford team turned circulating natural killer cells from human blood donors into a tissue-resident form, better suited to living and fighting inside tissue, by briefly exposing them to a signaling protein called TGF-b.

The dose of TGF-b mattered. A brief burst, delivered by human tumor cells in the lab, produced tissue-resident cells with strong tumor-killing activity. A constant supply of TGF-b instead produced tissue-resident cells that were inhibited and could not kill, the researchers found.

In mouse experiments, the enhanced cells slowed the growth of several types of solid tumors. Pairing the cells with an antibody treatment that helps them recognize cancer cells reduced tumor growth further. Because natural killer cells do not trigger an immune reaction when transferred between people, the researchers said a therapy built from them could potentially be manufactured in large batches and given to patients as needed, rather than custom-made from each patient's own cells. "It would be almost an off-the-shelf drug," Sunwoo said. "It could make cell therapy much more accessible to a wider variety of patients."