On Sept. 23, 2019, University of California, Los Angeles (UCLA) researchers announced they have harnessed the power of iNKT cells to attack tumor cells and treat cancer by suppressing the growth of multiple types of human tumors that had been transplanted into the animals.

Scientists have hypothesized that iNKT cells could be a useful weapon against cancer because it has been shown that they are capable of targeting many types of cancer at once — a difference from most immune cells, which recognize and attack only one particular type of cancer cell at a time. But most people have very low quantities of iNKT cells; less than 0.1% of blood cells are iNKT cells in most cases.

The researchers’ goal was to create a therapy that would permanently boost the body’s ability to naturally produce more iNKT cells. They started with hematopoietic stem cells — cells found in the bone marrow that can duplicate themselves and can become all types of blood and immune cells, including iNKT cells. The researchers genetically engineered the stem cells so that they were programmed to develop into iNKT cells. 

They tested the resulting cells, called hematopoietic stem cell-engineered invariant natural killer T cells, or HSC-iNKT cells, on mice with both human bone marrow and human cancers — either multiple myeloma (a blood cancer) or melanoma (a solid tumor cancer) — and studied what happened to the mice’s immune systems, the cancers and the HSC-iNKT cells after they had integrated into the bone marrow.

They found that the stem cells differentiated normally into iNKT cells and continued to produce iNKT cells for the rest of the animals’ lives, which was generally about a year.