Engineering the Next Generation of CAR T-Cells: Precision Modifications, Logic Gates and Universal Strategies to Overcome Exhaustion and Tumor Resistance

Juan Esteban Garcia-Robledo^1,2Sergio Cabrera-Salcedo^1,3Andreas Michael Brandauer^4,5Francesco Romano^4,5Joshua Rengifo-Martinez^1,6Alejandro Toro-Pedroza^1,7Juan Sebastián Victoria¹Lady Johana Rios^1,8Alexandre Loukanov^1,9Andrés Felipe Cardona¹⁰Pietro Genovese^4,5JUAN BAENA^1,11*

• ¹LiliCAR-T Group, Fundación Valle del Lili, Cali, Colombia
• ²IDC Instituto de Cáncer Hemato Oncólogos, Cali, Colombia
• ³Faculty of Health Sciences, Universidad Icesi, Cali, Colombia
• ⁴Division of Hematology/Oncology, Boston Children´s Hospital, Boston, United States
• ⁵Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, United States
• ⁶Clinical Research Center, Rio Grande Urology, El Paso, United States
• ⁷Faculty of Health Sciencies, Universidad Icesi, Cali, Colombia
• ⁸Universidad Icesi, CIRAT: Centro de Investigación en Reumatología, Autoinmunidad y Medicina Traslacional, Cali, Colombia
• ⁹Department of Chemistry and Materials Science, National Institute of Technology, Gunma College, Maebashi, Japan
• ¹⁰Centro de Tratamiento e Investigación Sobre Cáncer Luis Carlos Sarmiento Angulo (CTIC), Bogotá, Colombia
• ¹¹Department of Hematology/Oncology, Fundación Valle del Lili, Cali, Colombia

Chimeric antigen receptor (CAR) T-cells are genetically engineered T lymphocytes modified to express a synthetic receptor that specifically recognizes tumor-associated or tumor-specific surface antigens in a TCR-independent manner, enabling precise recognition and attack of cancer cells, leading to targeted tumor cell elimination1. Since 2017, seven CAR T-cell products have been approved by the US Food and Drug Administration (FDA) for the treatment of B-cell acute lymphoblastic leukemia (BALL), diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL), mantle cell lymphoma (MCL), chronic lymphocytic leukemia (CLL), and multiple myeloma (MM)2. CAR T-cell therapy has significantly improved overall survival (OS) in patients with large B-cell lymphoma and progression-free survival (PFS) in patients with MM3. Patients with FL and MCL have also achieved long-lasting remissions following CAR T-cell therapy1. The dramatic effectiveness of CAR T-cell therapy in blood cancers has made researchers and clinicians to consider its use on other conditions including solid tumors, infectious diseases, autoimmune disorders4 and transplant-related graft-versus-host-disease (GvHD)4,5. In the field of solid tumors, conventional CAR T-cells have been shown to possess multiple weaknesses that have hindered their applications and effectiveness for tumor eradication. Most of these flaws are related to the inconsistent and heterogenous expression of the target antigen on cancer cells and a myriad of physical/chemical and molecular challenges imposed by the tumor microenvironment (TME), causing high rates of antigen escape, selection of cancer clones that do not express the target antigen and T-cell dysfunction6. Therefore, preclinical studies and early clinical studies of conventional CAR T-cells on solid tumors have had disappointing results7,8. To overcome these challenges and limitations, researchers have engineered multiple mechanisms to modify CAR T-cell behavior, making them suitable to navigate the TME and be effective in solid tumor elimination. The next generation of CAR T-cell therapies under development integrate innovative strategies to enhance T-cell potency, tumor heterogeneity, and improve current treatments by reducing its toxicity, thus broadening the pool of patients that can benefit from it. In this review we will cover some of the most promising advancements recently made in this field and their potential clinical applications.