Doctors have infused cells edited using CRISPR-Cas9 into two patients in a trial conducted at the University of Pennsylvania, NPR reported on April 16. A university spokesperson confirmed in an emailed statement to The Scientist that the trial is underway and that two patients, one with multiple myeloma and one with sarcoma, have been treated so far. The study is the first instance of patients in the United States being treated with a CRISPR-based therapy.

In an interview with The Scientist in June 2018, the leader of the study, oncologist Edward Stadtmauer, explained that CRISPR would be used as a tool in a new type of immunotherapy. His team would filter T cells from the blood of eligible patients with cancer, then use the gene-editing technique to knock out three of the cells’ existing receptors and, with a lentiviral vector, insert the gene for a receptor called NY-ESO-1, a protein that appears on the surface of some cancer cells. The modified cells would then be expanded for a few weeks in the lab. Patients would receive a brief course of chemotherapy, after which the cells would be infused back into them.

In addition to cancer applications, researchers are exploring the use of so-called ex vivo CRISPR editing—in which cells are altered outside the body and then given to patients—to treat blood disorders such as β-thalassemia and sickle cell anemia. Other teams are working to develop therapies that would edit genes at fault in genetic diseases inside patients’ bodies.