State of the art in CAR-based therapy: In vivo CAR production as a revolution in cell-based cancer treatment

Chimeric antigen receptor (CAR) therapy has successfully treated relapsed/refractory hematological cancers. This strategy can effectively target tumor cells. However, despite positive outcomes in clinical applications, challenges remain to overcome. These hurdles pertain to the production of the drugs, solid tumor resistance, and side effects related to the treatment. Some cases have been missed during the drug preparation due to manufacturing issues, prolonged production times, and high costs. These challenges mainly arise from the in vitro manufacturing process, so reevaluating this process could minimize the number of missed patients. The immune cells are traditionally collected and sent to the laboratory; after several steps, the cells are modified to express the CAR gene before being injected back into the patient's body. During the in vivo method, the CAR gene is introduced to the immune cells inside the body. This allows for treatment to begin sooner, avoiding potential failures in drug preparation and the associated high costs. In this review, we will elaborate on the production and treatment process using in vivo CAR, examine the benefits and challenges of this approach, and ultimately present the available solutions for incorporating this treatment into clinical practice.