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Main textOver the past decade, autologous CAR-T therapies have shown remarkable success in treating hematological malignancies. However, their accessibility remains limited, which can be attributed to the complex manufacturing process involving the patient’s cells and the limited capacity of manufacturing sites, both of which contribute to the high cost of the therapy. These factors have resulted in prolonged and uncertain turnaround times for the production of these therapies, rendering a sizable population of patients ineligible for treatment due to the deterioration of their medical condition while they wait for treatment.

To resolve this issue, the field has delved into rapid manufacturing platforms. Here, we discuss approaches toward rapid CAR-T manufacturing, examine its impact on different stakeholders in the landscape, and provide insights into future directions for the field.

Approaches toward rapid manufacturing of CAR-T therapiesThe conventional clinical CAR-T manufacturing workflow involves leukapheresis, enrichment, activation (2–3 days), CAR gene insertion (1–2 days, typically performed through viral transduction with <50% efficiency), expansion (>7 days), formulation, and cryopreservation. Rapid CAR-T manufacturing have been approached via acceleration and/or simplification of the above workflow ( ^{Figure 1} ).

Workflow accelerationWorkflow acceleration seeks to obtain CAR-T products with similar cell yields but within a shorter timeframe by refining unit operations of conventional workflows. The critical quality attributes (CQAs) and release criteria of the manufactured products are projected to remain unchanged or similar to those established in conventional workflows.

Enhancing the efficiency of CAR gene insertion and expediting cell expansion are pivotal factors for this approach. In particular, CAR gene insertion could benefit from advanced gene integration technologies, such as CRISPR/Cas9 [ ¹] or transposon systems [ ²], and cell expansion could be hastened by optimizing various culture parameters, such as media formulation, feeding strategy, and cell density. Machine learning could aid the optimization processes, as demonstrated in a study in which a base media formulation optimized for cell viability and expansion in a 6-day culture was generated through a model with a training data set obtained from 104 cultures [ ³].

One example of this rapid manufacturing approach is evident in Kite Pharma’s amended manufacturing protocol for its CAR-T product, Yescarta, announced earlier in 2024. Kite Pharma successfully shortened its manufacturing time by 2 days and proved comparability between the original and amended protocols ^i.

Workflow simplificationWorkflow simplification aims to enrich highly efficacious CAR-T _stem cells (depending on the protocol and product, this population can comprise central memory T cells, naïve T cells, stem cell memory T cells, or a combination thereof) in the final product with short-term culture. This can dramatically reduce the manufacturing turnaround time from 10–12 days to 1–3 days, or even the next day. Given the emphasis on CAR-T _stem cells, the CQAs and release criteria of the manufactured products are expected to differ from those established in conventional workflows.

This strategy arose from findings that CAR-T products containing cells of greater stemness demonstrated improved persistence and efficacy in clinical trials [ ⁴]. Therapies manufactured by this approach rely on a much lower dosage (10 ⁶–10 ⁷) of T _stem cells, which have superior in vivo proliferative potential and are abundant in the early stages of ex vivo culture. Consequently, this approach drastically reduces or even eliminates the need for ex vivo expansion, allowing for the entire omission of cell expansion and (possibly) cell activation operations [ ⁵, ⁶] from the conventional workflow.

Establishing novel and suitable CQAs and release criteria (including cell phenotype, yield, and function) and aligning them with advanced process analytical technologies are crucial in this approach. Notably, cells manufactured by this approach may not have completed the CAR gene integration process by the end of the ex vivo manufacturing. New methods to examine the presence of edited genes, such as using quantification of reverse transcription intermediates, may be useful in this regard [ ⁶].

An example of this approach was explored in a clinical study sponsored by Novartis. The study compared the conventional workflow-produced CAR-T product, Kymriah, with a T _stem-enriched variant produced through the T-Charge platform, in which T cells were cultured for <2 days. The study demonstrated that the T _stem-enriched version had comparable efficacy and a favorable safety profile despite being administered at 10–100 times lower dosage [ ⁷].

Impact of rapid CAR-T manufacturingThe direct impact of rapid CAR-T manufacturing is evident in the cell therapy manufacturing sector due to its ability to overcome current hurdles, such as workforce shortages, and in implementing decentralized and point-of-care (POC) models of manufacturing. Additionally, rapid CAR-T manufacturing also aids shortening the vein-to-vein time and improving predictability in treatment start times, delivering substantial benefits to patients and other key stakeholders in the healthcare system ( ^{Figure 2} ).

Alleviating workforce shortagesConventional manufacturing of autologous CAR-T therapies involves a predominantly manual scale-out process, which requires highly skilled workforce who can perform consistently in a high-stress current good manufacturing practice (cGMP) environment. As a result, a skilled workforce remains a pressing need in the industry [ ⁸] and the launch of training programs worldwide is clear evidence for the need to develop this workforce [ ⁹]. Rapid manufacturing reduces cleanroom turnover time, allowing facilities to produce more treatments with a smaller workforce. Together with automated platforms, such as advanced bioreactors [ ¹⁰], rapid CAR-T manufacturing has the potential to drastically reduce human intervention and to address the workforce shortage in the industry.

Towards decentralized and POC models of manufacturingDecentralized and POC models of manufacturing have often been proposed as a key solution to improve CAR-T treatment accessibility, but hurdles, such as cross-site process variability and high infrastructure costs, have hindered their implementation [ ¹¹]. Rapid manufacturing has the potential to effectively address these hurdles. By streamlining the workflow and shortening the manufacturing cycle, it minimizes overall process variabilities to enable a smoother technology transfer between manufacturing sites. With reduced culture capacity (for the approach of workflow simplification), it also diminishes the footprint of the process, and subsequently lowers the infrastructure cost of the cGMP facility. Together with the development of compact closed cell manufacturing systems, it can reduce the need for high-grade clean rooms by allowing manufacturing in GMP-in-a-box. The implementation of a decentralized/POC manufacturing model may also eliminate additional steps in the conventional manufacturing workflow, such as cryopreservation and packaging, further reducing time and cost ( ^{Figure 1}).

Concluding remarks and future perspectivesRapid manufacturing of CAR-T products via workflow acceleration takes advantage of the clinical and regulatory experience of conventionally manufactured CAR-T products, although its workflow complexity remains a limiting factor. Workflow simplification presents a streamlined approach due to its potential to significantly reduce manufacturing turnaround time and minimize the number of process steps. However, it necessitates significant efforts to establish process and product knowledge. If comparable clinical evidence can be collected to confirm the safety and effectiveness of products, workflow simplification can outpace workflow acceleration and emerge as the preferred manufacturing trend. With workflow simplification, the bottleneck in the CAR-T cell manufacturing cycle would be shifted to release testing, which conventionally includes a 14-day sterility test following US Pharmacopeia <71> guidelines. Rapid sterility testing utilizing highly sensitive cytometry systems [ ¹²], or non-growth-based methods [ ¹³], such as sequencing, can reduce the test time significantly to a few days or even hours. Their advancement will be the next disruptive step that can perfectly complement the transition of CAR-T manufacturing toward the decentralized/POC model ( ^{Figure 1}) and enable further shortened vein-to-vein time.

Given that the number of patients receiving CAR-T is expected to increase due to expanded therapy indications, there is an mounting need for treatment accessibility. Rapid manufacturing appears poised to address this need by enabling decentralized models of manufacturing; however, its implementation is not straightforward and would face challenges, including workforce training, facility availability, and supply chain logistics [ ¹¹]. In addition, we must remember that other activities in the CAR-T treatment value chain, such as patient selection, bridging therapy, and patient management, also significantly impact the patient journey. Thus, enhancing the efficiency of these activities alongside rapid manufacturing is crucial for maximizing the potential of rapid CAR-T manufacturing and the broader adoption of CAR-T therapy.