Figure 1. CAR-expressing T cell production to develop immunotherapeutics. (I) Themeli et al. transduced a healthy volunteer's T cells with two retroviral vectors encoding four transcription factors that reprogram the T cells into induced pluripotent stem (iPS) cells. The iPS cells then were transduced with a lentiviral vector encoding a chimeric antigen receptor (CAR) to provide CAR-expressing iPS cells. The team next differentiated the CAR-expressing iPS cells into T cells using a 3-step, 30-day protocol that takes the cells through phases of embryoid body formation, hematopoietic precursor specification and finally T cell commitment.

The resulting T cells expressed both the CAR and an endogenous T cell receptor (TCR) that matched the original TCR of the patient-obtained T cell. Methods to expand the CAR-expressing, iPS cell-derived T cells resulted in a 1,000-fold increase in numbers.

(II) CAR-expressing T cells also can be directly engineered from patient-obtained T cells using the lentiviral vector encoding CAR. Methods to expand the CAR-expressing T cells are not as proficient as those to expand CAR-expressing, iPS cell-derived T cells.