Clinical Report: Breaking the Size Barrier in CAR T Engineering

Overview

Researchers at the University of Pennsylvania have developed an optimized workflow that significantly enhances the efficiency of generating CAR T cells with large lentiviral transgenes, exceeding 10 kilobases. This advancement addresses a critical manufacturing bottleneck, improving transduction rates and functional viral titers, which could facilitate the development of more complex CAR T cell therapies.

Background

CAR T cell therapies have revolutionized the treatment of various blood cancers, yet the incorporation of larger transgenes poses significant challenges in manufacturing. As the size of transgenes approaches or exceeds 9 kb, traditional lentiviral vectors struggle with transduction efficiency, complicating the production of next-generation CAR T cells. Addressing these challenges is crucial for advancing CAR T cell therapy and expanding its therapeutic applications.

Data Highlights

Key Findings

• The optimized workflow improved transduction efficiency by 10-12 fold for the 10.1 kb construct.
• T-cell transduction rates increased by up to 14.8-fold compared to conventional methods.
• Transduction rates of 60-70% were routinely achieved for constructs around 9 kb.
• The protocol eliminated the need for cell sorting to enrich engineered cells.
• The modified protocol supported robust T-cell expansion without signs of toxicity.

Clinical Implications

The enhanced efficiency of lentiviral delivery for larger genetic constructs may reduce manufacturing costs and improve access to advanced CAR T cell therapies. This workflow could also be adapted for other immune cell types, potentially broadening therapeutic applications beyond current indications.

Conclusion

The introduction of this optimized workflow represents a significant advancement in CAR T cell engineering, addressing key manufacturing challenges and paving the way for more complex and effective therapies in hematologic malignancies.

References

1. The ASCO Post, 2025 -- Reducing the Barriers to Receiving CAR T-Cell Therapy for Patients With Hematologic Malignancies
2. The Medicine Maker, 2026 -- Could Mass Spec Overcome the CAR T Solid Tumor Barrier?
3. Bone Marrow Transplantation, 2025 -- Indications for haematopoietic cell transplantation and CAR-T for haematological diseases, solid tumours and immune disorders: 2025 EBMT practice recommendations
4. Oncology Nursing News, 2024 -- Survival Benefit, Durable Responses Continue at 3 Years With Liso-cel in Second-line LBCL
5. The ASCO Post — Reducing the Barriers to Receiving CAR T-Cell Therapy for Patients With Hematologic Malignancies
6. Franklin / MDSpire — Current Ex Vivo CAR-T Benchmarks Define the Bar for Emerging In Vivo CRISPR-Based T Cell Engineering
7. Indications for haematopoietic cell transplantation and CAR-T for haematological diseases, solid tumours and immune disorders: 2025 EBMT practice recommendations | Bone Marrow Transplantation
8. Survival Benefit, Durable Responses Continue at 3 Years With Liso-cel in Second-line LBCL | Oncology Nursing News
9. CARTITUDE-4 Update: Cilta-Cel Improves OS in R/R MM