New Approach Obviates Need for Lymphodepletion before Adoptive T Cell Therapy

The typical process for CAR-T cell therapy involves the removal of a patient's T cells, which are then engineered in a lab to incorporate chimeric antigen receptors (CAR) designed to target specific proteins on the surface of cancer cells. These genetically modified CAR-T cells are subsequently reintroduced into the patient's body to combat the cancer. However, this procedure is quite extensive and expensive, involving a preparatory step known as lymphodepleting chemotherapy, which eliminates the patient's existing T-cells to create a clean slate for the CAR-T-cells to operate.

While CAR-T cell therapy has led to incredible recoveries in some patients, it has also been associated with severe and sometimes frightening side effects, partly due to the lymphodepleting chemotherapy. Now, researchers at MUSC Hollings Cancer have found that this chemotherapy step might not be necessary.

Their research, published in Molecular Therapy, focused on encoding CAR-T cells with instructions to create a hyperactive form of the STAT5 protein. These instructions promoted the engraftment of CAR-T cells without the need for lymphodepletion. This engraftment process, they found, was cell-autonomous, meaning it occurred independently within the cells and was not influenced by external factors.

By activating STAT5 during the initial phase of adoptive transfer, the researchers effectively tricked the CAR-T cells into thinking they were entering a lymphodepleted environment. As a result, the cells engrafted effectively, functioned as intended, and demonstrated their capability through various benchmarking assays.

What makes this research particularly promising is its potential to eliminate the need for lymphodepleting chemotherapy, making CAR-T cell therapy viable for treating a wider range of diseases. This therapy has shown tremendous potential beyond cancer, particularly in conditions like lupus, where the balance between benefits and harms of lymphodepletion is different from that in recurrent lymphoma cases.

Moreover, this shift away from lymphodepletion could bring about changes in dosing schedules. Instead of one-time treatments, patients could receive multiple injections over time, potentially improving the effectiveness and convenience of CAR-T cell therapy.