Optimizing CAR-T Cell Manufacturing Processes during Pivotal Clinical Trials

Abstract

Tisagenlecleucel is a CD19-specific chimeric antigen receptor (CAR)-T cell therapy approved for patients aged ≤25 years with relapsed or refractory B cell precursor acute lymphoblastic leukemia (B-ALL) and adults with relapsed or refractory diffuse large B cell lymphoma (DLBCL). The initial tisagenlecleucel manufacturing process technology was developed at an academic center and was subsequently transferred, optimized, validated, and scaled out to supply large global trials before commercialization. Tisagenlecleucel manufactured in two centralized facilities has been successfully used in global multicenter trials for B-ALL and DLBCL (>50 clinical centers in 12 countries). In this paper, we describe some of the continuous process improvements made to tisagenlecleucel manufacturing over time to meet global demand while maintaining and improving product quality. During early tisagenlecleucel clinical trials, process enhancements were made to address logistical challenges related to manufacturing for multicenter trials and to accommodate the variability observed in patient starting cellular material. These enhancements resulted in improvements in manufacturing capacity, process robustness, manufacturing success rates, and product quality, and reductions in throughput time. In summary, through continuous evaluation and improvements based on experience during global trials, a consistent and robust commercial manufacturing process for tisagenlecleucel has been developed, leading to improvements in manufacturing success when compared to the initial processes.

Keywords: chimeric antigen receptor-T cell therapy; commercial manufacturing; global manufacturing; immunotherapy; manufacturing process optimization.

Figure 1

Tisagenlecleucel Structure and Manufacturing Process (A) Structure of tisagenlecleucel CAR. (B) Tisagenlecleucel manufacturing process. CAR, chimeric antigen receptor.

Figure 2

Step-Based Approach for Process Transfer GMP, good manufacturing practice.

Figure 3

Assessment of Comparability during Technical Transfer (A) Comparison of process performance. (B) Demonstration of statistical comparability. EAC, equivalence acceptance criteria; VSV-G, vesicular stomatitis virus G. Population doubling level is a metric that indicates the cumulative number of cell doublings over the course of the culture.

Figure 4

Implementation of Logistical Controls and Maintaining Chain of Identity

Figure 5

Examples of Process Improvements (A) Improved T cell enrichment: cell growth curves and population doubling were comparable, and transduction efficiency was comparable or higher using the modified T cell enrichment process versus historical methods. (B) Improved culture media: cell growth, white blood cell (WBC) counts, and transduction efficiency were comparable in batches that used reduced serum versus historical batches. (C) Facility and operational improvements; modular facility design. LEL, lower equivalence limit; UEL, upper equivalence limit. Population doubling level is a metric that indicates the cumulative number of cell doublings over the course of the culture.

Figure 6

Commercial Manufacturing Process for Tisagenlecleucel (A) Commercial manufacturing target timelines (median throughput time, 23 days; range, 21–37 days). (B) Throughput time in the first 37 commercial patients. (C) US sites that received commercially manufactured tisagenlecleucel. Stars in (C) indicate locations of the 13 unique sites where 37 patients received commercially manufactured tisagenlecleucel.

Figure 7

Manufacturing Experience from the ELIANA Clinical Trial (A) Consistent T cell product from variable patient leukapheresis material. (B) Positive patient outcomes across a range of transgene positive cells and copy numbers. CAR, chimeric antigen receptor; CR, complete remission; CRi, complete remission with incomplete blood count recovery; NK, natural killer; NR, nonresponder; qPCR, quantitative polymerase chain reaction.