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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5608_Библиотеки_им_академика_М_И_Перельмана.pdf
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The duration of cell culture should be ne-tuned to the clinical dose. However,
maintaining CAR-T cells too long in exvivo culture may drive the cells toward an
exhausted phenotype, as a shorter culturing time has been shown to be associated
with positive clinical outcomes [39]. During manufacturing optimization, Kite
shortened the expansion time of Yescarta to 6–8days and still met clinical dose of
2E6 CAR-T cells/kg of body weight [43].
9.3.7 In-Process andRelease Testing
The lack of approved and well-dened standardized testing is a continuing challenge for the growing eld of CAR-T manufacturing despite regulatory requirements to test for safety, purity, and potency [17]. As many advancements in CAR-T
development occur at academic centers [49] which do not often interface with regulatory agencies [50], it is difcult to centralize the numerous testing protocols and
approaches for clinical manufacturing. Post-manufacturing quality control is a particular area of concern as any delays in release testing will translate to delays for
CAR-T administration to patients. While validated assays are not typically required
during product development, the relatively quick approval that can happen with
CAR-T therapies (i.e., Kymriah received marketing approval in the United States
after just 106 patients were treated) [50] necessitates a robust testing strategy be
identied as quickly as possible.
Over the course of manufacturing, it is critical to quantify and/or qualify cell
identity and functionality. Flow cytometry is a standard analytical method in CAR-T
manufacturing due to its high specicity and ability to identify many cell types
simultaneously. However, ow cytometry is notoriously complex and can be subjective. The choice of ow cytometer should be guided by the number of dyes to be
detected in the process, and the lasers and detectors that are appropriate for the
number and color of dyes to be used. To reduce variation and improve standardization, ow cytometry cartridge-based systems that use machine learning to automatically identify populations are in development by companies like Accellix. A simple
to use and automated ow cytometry assay may be one way to reduce costs and the
number of highly trained full-time employees (FTEs) required for manufacturing.
Weil etal. propose applying diagnostic pathology assay standards to cell therapy
quality control testing and have suggested detailed lists of acceptability criteria for
ow cytometry and hematology blood analyzers including guidelines around instrument maintenance, assay controls and sample running, and analysis guidelines [50].
Proving cellular potency is a key requirement for release of CAR-T cells and
remains a challenge not encountered in more traditional biopharmaceuticals.
Potency assay development can be a particularly challenging part of CAR-T development due to variability of autologous starting materials, limited sample availability, lack of reference standards, distinguishing cytotoxic contributions of multiple
cell subtypes, and discrepancies between in vivo and invitro behavior [51, 52].
There is a regulatory challenge as well as potency measurements are uniquely
9 CAR-T Bioprocessing
241
designed for each product. In the United States, the FDA does not provide recommendations regarding specic assay types or acceptance criteria and notes that
potency assays may evolve as more knowledge is gained about the product during
development. Additionally, the FDA does suggest orthogonal assay development, as
a singular assay alone may not fully demonstrate potency [51]. While this allows for
considerable exibility for the manufacturer, the lack of dened standards can be
challenging. It may also be worthwhile to measure a wide range of product attributes as early as possible, and such exploratory studies can help identify which
attributes correlate with cellular potency.
The key assumption of the potency assay is that the killing ability of the CAR-T
cell product measured invitro is an appropriate proxy of the invivo killing capabilities. This assumption is fundamentally complicated by the biological variability of
the patient population.
Cytotoxicity is measured by exposing CAR-T cells, known as effector cells, to
the target cancer cell, and using target cell viability to determine the killing ability
of the effector cells [52]. The effector and target cells can be mixed at different
effector to target ratios (E:T). Assays to measure CAR-T cytotoxicity include chromium release, luciferase-mediated bioluminescence imaging, ow cytometry, cytokine measurement, and impedance [53].
In the chromium release assay, the target cells are labeled with radioactive chromium. As the target cells are killed by the CAR-T cells, chromium is released, and
the amount of target cells killed is proportional to measured radioactivity. With the
luciferase assay, no radioactive materials are required. Target cells are transduced
with a luciferase reporter gene and only viable cells produce luciferase. As effector
cells kill target cells, bioluminescence decreases since luciferase can no longer be
produced [53]. Flow cytometry-based cytotoxicity assays uses a live/dead staining
reagent, such as 7-AAD, to measure dead target cells. As suggested previously in
this section, ow cytometry is not necessarily a preferred method due to the level of
technical expertise required and subjectivity that can inuence data analysis.
Cytokine measurement assays can be used as an indirect measure of proxy
potency. One class of cytokine-based functionality assays measure cytokines, such
as interferon gamma, released by activated effector cells. Granzyme B and perforin
detecting assays can also be used to measure functionality. A noteworthy recent
development suggests that interferon gamma does not necessarily correlate with
better killing ability of effector cells in liquid tumors [54].
One advantage of the impedance-based assays for cytotoxicity is that the target
cells do not need to be labeled. However, this assay class measures impedance due
to target cells, thereby requiring the target cell population to be either naturally
adherent or made to be adherent. In this assay, the presence of microelectrodes on
the bottom of a microtiter well allows for the measurement of impedance due to the
target cells. The effector cells are in suspension. As effector cells kill target cells,
impedance changes due to the decrease in target cell population [53].
Specialized instruments for the impedance assay are the xCELLigence, Incucyte,
and Maestro ZHT platforms. These instruments can be of particular use to pursue to
simultaneous development of multiple potency assays over the course of drug
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A. Adeniran et al.
development as suggested by the FDA [51]. In addition to providing impedance
measurements, these instruments can also be used for cytokine secretion assays.
The supernatant from the co-culture can be isolated and evaluated for the presence
of cytokines. The manufacturer should ensure any instrument and software used in
the evaluation of potency is 21 CFR compliant. To date, the Maestro ZHT and
xCELLigence platforms meet 21 CFR compliance.
A critical aspect of potency assays to consider is how representative the invitro
assay is of the invivo environment. In vivo, CAR-T cells must overcome the tumor
microenvironment, which can be characterized by the presence of immunosuppressive factors and hypoxia. As the CAR-T eld builds upon the success of
treating hematological cancers and expands toward treatment of solid tumors, it is
important to consider the 3D environment in which the CAR-T needs to demonstrate functionality. Interestingly, a weakened cytotoxic response is observed from
CAR-T cells applied to a spheroid of target cells as opposed to a monolayer of target
cells at the same E:T ratios [52].
Discussion around types of qualication assays needed for the production and
release of GMP lentiviral vectors has been debatable. Qualication assays should
demonstrate titer, potency, identity, purity, and safety of the vectors. In developing
types of qualication assays, it is important to understand that these assays need to
demonstrate that the vector is safely carrying out its intended role for which it is
developed for, while exhibiting high efcacy. Characteristics for release can vary,
and sometimes more than one type of assay, dual testing, may be required. White
etal. summarizes a approaching regulatory considerations for the use of lentiviral
vectors in respect to the types of characteristics that should be assessed and how to
develop proof-of-concept studies to demonstrate vector attributes which satisfy
regulatory requirements.
As described earlier in this chapter, these vectors are derived from pathogenic
viruses which pose the risk of RCR/RCL generating during recombination events.
Testing for replication-competent lentiviruses and retroviruses safeguards against
any undesired recombination events postinfusion that may result in new replicationcompetent viruses. The utility of this test is debatable, as to date, no CAR-T products have reported a positive RCR/RCL result [55]. Previous recommendations
from the FDA suggest testing material, including vector supernatant and cell products transduced with vector, from multiple stages of product manufacture as RCR
may develop at any stage during manufacturing [56]. This can vary depending on
the mode of production, whether via transient transfection or via stably transfected
producer cell lines, type of vector envelopes used and if the effector CAR-T cells
will be administered exvivo or invivo so it is important to remain current on regulatory recommendations.
Assays to assess for RCR may consist of the vector supernatant being co- cultured
with a permissive cell line to allow for amplication of potential RCR.The amplied material can then be assessed for the presence of RCR by utilizing appropriate
indicator cell assays such as PERT which measure the activity of reverse transcriptase, PCR detecting viral sequences, or the commercially available p24 ELISAbased assay. It is critical to optimize these assays and to develop appropriate
9 CAR-T Bioprocessing
243
standards and controls to increase assay specicity, sensitivity, and reproducibility.
FDA has recommended two methods: (1) serologic detection of RCR-specic antibodies; and (2) analysis of patient peripheral blood mononuclear cells by PCR and
RCR-specic DNA sequences. Again the choice of the assay will depend on the
type of vector [56].
Assays may assess the properties and biological effects of the promoter sequence,
transgene, and gene product delivered for the intended clinical application [57]. For
CAR-T cells transformed by viral vectors that integrate the CAR-T in the cell
genome, vector copy number (VCN) should be measured as too high of VCN carries an increased risk of oncogenesis. The FDA recommends a VCN <5 copies per
cell [13]. Digital droplet PCR and real-time quantitative PCR are both feasible
options for VCN measurement [58, 59].
CAR-T products must be tested for sterility prior to patient infusion. The standard 14-day sterility test is not feasible when CAR-T products should be administered as quickly as possible to patients. Therefore, a conditional release may be
made after a 3- or 4-day sterility test showing no contamination with the caveat that
the full 14-day sterility test will be completed [55]. Undoubtedly, patient safety
must remain the highest concern in the production and administration of CAR-T
therapies. However, streamlining the testing requirements may get medicines to
patients faster and at a lower cost.
9.3.8 T-Cell Cryopreservation
Once the cell expansion step achieves the target number of nucleated cells within
the mixture, the nal formulation of T cells starts with two cell washing cycles followed by a buffer exchange step. The T-cell mixture is rst centrifuged within the
same closed chamber used for cell expansion, then the supernatant cell expansion
buffer is aspirated out of the chamber and replaced with a formulation buffer made
of an extracellular protective agent such as human serum albumin (HSA) and saline
solution suitable for intravenous (IV) infusion. The formulation buffer helps retain
the cells in a balanced solution in terms of osmolality and pH to suit IV infusion;
however, it provides limited protection from ice crystal formation during the freezing stage required for the proposed storage conditions for biologics in liquid
nitrogen.
Successful cryopreservation limits crystal formation during the freezing stage
while keeping the osmolality and pH values within the acceptable limits of IV infusion, thus maintaining CAR-T cell phenotype and function while retaining viability
with 50–90% recovery post-thaw [55, 60]. Therefore, cryopreservation methods
developed for hematopoietic cells are mostly adopted for CAR-T cell manufacturing as well even though some recent studies have pointed out to the potential adverse
effects of cryopreservation on the vital characteristics of CAR-T cells [25]. These
methods generally involve resuspension of cells in isotonic buffers (e.g., saline for
IV infusion) containing 10% dimethyl sulfoxide (DMSO) before transferring to
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A. Adeniran et al.
controlled rate freezer prior to storing in vapor phase liquid nitrogen (VPLN) [61].
Lower concentrations of DMSO can be also used once mixed with extracellular
protective agents (e.g., hydroxyethyl starch (HES) solutions, HSA, serum, and
plasma), and they can be available commercially as preformulated Cryostor at nal
DMSO ratios of 2%, 5%, and 10%. Recent studies have also pointed out to the
potential of using pentaisomaltose to help reduce DMSO ratios down to 1% in the
nal formulation for effective cryopreservation of CAR-T cells [62]. Considering
the adverse effects of DMSO on cell viability, it is clinically regulated to not exceed
1 gr/kg as per European Society of Bone Marrow Transplantation (EBMT) and the
American Association of Blood Banks (AABB) [63].
The freezing rate is also another important factor in controlling the formation of
ice crystals, so controlled rate freezers are used to tune the temperature prole during freezing to manipulate the physical state of water molecules. The ne manipulation of the physical state of water molecules along with the use of cryopreserving
agents can signicantly limit the formation of ice crystals in the nal cell formulations during freezing stage thus maintaining cell viability and stability for extended
periods of storage. Previous methods suggest freezing CAR-T cell products passively in −80°C deep freezers, but the more recent approaches adopted for GMP
manufacturing involve using controlled rate freezers (CRF) to achieve a temperature reduction rate at 1°C per minute to better limit the formation of intracellular ice
crystals [64]. Cells can be later transferred to VPLN for storage at temperatures less
than −150°C once sufciently hydrated to withstand the sudden reduction in temperatures [17, 65]. The main advantage of using CRFs from a quality perspective is
the consistency of freeze with the versatility of programming and data traceability
for individual products, and new mechanical CRFs (e.g., asymptotes) can overcome
the high costs and safety concerns associated with the heavy use of LN2 to run traditional CRFs in closed spaces [17].
Validating the cryopreservation step is a crucial quality requirement for largescale manufacturing as suboptimal cryopreservation can lead to reduced numbers of
viable cells with increased levels impaired cell phenotype and functions [66].
Therefore, stability testing is routinely performed on individual products to ensure
preserved viability, expression of CAR transgene, and functional capability (cytotoxicity or cytokine release data) over time according to established assays. To
maintain traceability, cryopreserved products are retrieved from VPLN and transported in temperature logged and validated LN dry containers by contracted couriers under principles of good distribution practice (GDP) prior to infusion in patients
in hospitals [1, 67].
9.3.9 Formulation Considerations fortheDrug Product
To prepare the nal formulation mixture, the dose to be infused—which correlates
to the number of CD3+ transduced T cells as a fraction of the total number of nucleated cells in a given volume of the formulation buffer—is calculated. Once the nal
9 CAR-T Bioprocessing
245
dose is calculated, the formulator then decides on the type and number of nal drug
product container closure systems (i.e., bags) suitable for the chosen dose. The
selection of the suitable bags takes into consideration different attributes of the nal
drug product according to the Quality Target Product Prole (QTPP) as referred to
in the pharmaceutical development quality guidelines Q8(R2). This dose system
can be updated over the progress of the clinical trials according to feedbacks from
clinicians as they gain more understanding of the cancer treatment regimen. Since T
cells can be considered as living drug modalities, the formulation procedure can be
a bit different from that of the other non-living drug modalities and must aim to
maintain cell metabolism and functionalities instead of physicochemical interactions with other excipients [68].
Dosing strategy should take into consideration the pharmacokinetic proles of T
cells where they can peak in 1–2weeks after administration and have been shown
to persist in some patients for up to 10years [1]. This in turn reects therapeutic
efcacy with a potential high drug exposure on the short term and a sustained functionality on the long term. Therefore, current dosing practices aim to design clinical
trials with patients split in multiple groups of three patients to accommodate a regimen of incremental dose increases to account for any potential toxicity at each
incremental increase [69]. To account for the assumption that dose toxicity would
only be modelled with simple scaling and monitoring, the rst group would start
with a dose considered safe (i.e., low concentration of TNC/mL), and the following
two groups would receive a dose with predetermined incremental increases and
monitored for toxicity. This has been shown in a recent Phase I study of anti-CD19
CAR-T cells where patients with relapsed/refractory B-cell non-Hodgkin’s lymphoma received escalating doses of 25×106 (n=3), 50×106, and 100×106 viable
CAR-positive T-cells [70].
Next generations of dosing strategies tended to enhance the potency of the DP by
adopting new formulation platforms which enhance T-cell stemness, thus signicantly reducing the dose level while maximizing the therapeutic effects of the nal
DP [39]. These strategies also aimed to minimize the invitro cell expansion time to
signicantly reduce the total vein-to-vein time and reect on a reduced cost of the
nal DP [71, 72]. On the other hand, these next-generation approaches also opened
the door toward future T-cell immunotherapeutics with improved activity against
solid tumors [73].
Considering the variabilities between different dosing strategies, the total number of cells required to meet the target doses of the high concentration group may
well exceed one order of magnitude that of the low concentration at a given clinical
study [74]. Therefore, the total volumes required to achieve target doses may be
split into several containers (bags or vials) prior to administering to patients. This
shows that formulation options can be quite limited to meet the QTTP requirements,
and design of these dosage forms can consider only few options such as primary
container type, ll volume, and cell concentration per dose to cover a target range of
106–108 CAR/TCR T-cells/mL.Table9.3 shows different clinical CAR-T cell therapies in different FDA approval stages with the different doses, primary containers,
and ll volumes.
246
Table 9.3 Comparison of the primary containers used to ll the allocated doses of marketed T-cell
drug products
T cell drug product
(Proprietary name) Dose (adults)
Brexucabtagene
autoleucel
(Tecartus™)
Axicabtagene
ciloleucel (Yescarta®)
Tisagenlecleucel
(Kymriah®)
Lisocabtagene
maraleucel
(Breyanzi®)
Ciltacabtagene
autoleucel
(CARVYKTI ®)
a
CD4 and CD8 components at 1:1 ratio
b
For each CD8 and CD4 component
2×106 per kg body
weight, max. 2×10
2×106 per kg body
weight, max. 2×10
0.6–6.0×10
0.5–1.1×10
0.5–1.0× 106 viable
T-cells per kg body
weight up to 1×10
8
8a
8
8
8
Primary
container
Cryogenic
infusion bag
Cryogenic
infusion bag
Cryogenic
infusion bag
Cryogenic
vials
Cryogenic
infusion bag
Fill volume
per container
~68mL 1
~68mL 1
10–50mL 1–3
4.6mL 1–4
30 or 70mL 1
A. Adeniran et al.
Number of
containers per
dose
b
9.3.10 Scale-Up Considerations: Toward
Automated Formulation
Qualication of the successful manufacturing process of T-cell drug products takes
into consideration different aspects of the procedures and components involved
such as raw materials, ancillary components, equipment, facilities, sampling plans
for quality control and analytical assays, standard operating procedures, and trained
personnel to consider it as a reproducible and robust manufacturing platform [75].
The quality and quantity of the harvested patient’s peripheral blood mononuclear
cells (PBMCs) will be highly amenable to the disease progression and the immune
state of their body following any potential chemotherapeutics. Lymphocytopenia
(low count of lymphocytes in blood) can be induced in some cancer patients following chemotherapies and can in turn have negative effects on T-cell proliferation rate,
phenotype, and transduction efciency which can eventually affect the dose to be
manufactured. Therefore, manufacturing strategies should take into account the feasibility of translating leukapheresis material from healthy donors used in formulation development to that of the cancer patients with compromised numbers of
PBMCs [69].
Considering the complex and lengthy workows involved in the routine manufacturing of autologous T-cells, developing a strategy to reduce the total costs of
goods for the effective delivery of vein-to-vein CAR-T cells becomes a necessity.
Since T-cell therapy is highly personalized and specic to each therapeutic area,
sourcing patient cells and ensuring their validated transport to GMP manufacturing
facilities from and back to patient introduces a lot of challenges with regard to process automation [76]. The current vein-to-vein procedures involve aseptic lling of
9 CAR-T Bioprocessing
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T-cell formulations into different containers at room temperature within strict time
schedules considering the presence of cryopreserving agents. This time constrains
drive the chemistry, manufacturing, and controls (CMS) strategy to adopt fully or
semi-automated formulation and lling steps where they can be integrated with
upstream cell processing steps to reduce contamination and time constrains [77].
One approach to address these needs is to have multiple validated centers to source
patient cells and transport them to central GMP manufacturing facilities to process
into appropriate dosed containers of drug products [78]. Considering these challenges, big pharma, and biotech companies are building partnerships with universities to facilitate this process and drive development costs down as well [79].
Adopting closed end-to-end workows for sterile production within ISO 14644-1
Class 7 cleanrooms (FDA Class 10,000 equivalent) is far more advantageous than
open process workows that require intensive manual steps under ISO 14644-1
Class 5 cleanrooms (FDA Class 100 equivalent). A two-phase process was demonstrated by the National Institute of Health Clinical Center where a modular system
involving two manufacturing phases was adopted to provide TCR-T cells to Phase
I/II clinical trials. The rst phase involved closed lymphocyte enrichment in culture
asks before transferring enriched cells into culture bags for transfection by day 7.
The second phase then moved the cells from culture bags into a closed culture apparatus to induce up to 1890-fold expansion by day 14 [80]. Fully closed and automated end-to-end process involving an advanced apparatus has shown high yields
of CAR-T cells after just 10days of expansion [81]. This in turn reects the amenability of both the semi and the fully automated methods to generate sufcient numbers of T-cells for different therapeutic regimens.
The formulation process starts with the bulk drug substance obtained from the
expansion step where the total number of nucleated cells (TNC) is used to calculate
the buffer volumes required to perform cell wash/concentration and resuspension/
dilution steps required to mix with DMSO and achieve the target TNC concentration in the nal drug product. In the manual formulation process, the formulator
makes the necessary resuspension/dilution steps to obtain the target TNC concentration before lling into nal container closure systems (e.g., bags, vials) [5]. On
the other hand, the closed systems with automated ll-nish process calculates the
cell concentration and dilution steps out of the TNC concentration value of the drug
substance to meet the target TNC concentration of the drug product [82]. The drug
product volume remaining minus the volume required for quality control is later
split into different bags at the validated ll volumes of the bags [68]. Bag material
is chosen to maintain a exible and robust structure with minimum leachable chemicals while enabling gaseous exchange of O2 and CO2 through permeation, and
current preference seems to favor bags made of ethylene-vinyl acetate (EVA) over
those made from poly vinyl chloride (PVC) for this purpose [83, 84]. These bags are
later over-wrapped and placed into metal cassettes to ensure uniform thickness during freezing for a uniform heat transfer upon freezing and thawing procedures considering the excellent heat conductivity of the metal cassettes [85].
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9.4 Supply Chain andLogistic Model
The overview, provided earlier in this chapter, describes the key process steps
required for the development of CAR-T drug products. Though these types of drug
products have demonstrated both clinical and therapeutic success harnessing much
attention, there can be a series of challenges that need to be addressed to bring
CAR-T cell drug products to market. It has been projected that demand will continue to grow, with forecasted patient numbers reaching 40,000 by the year of 2031
[86]. Current supply chain models for CAR-T cell drug products, for instance in the
UK, only provide treatment to a nite number of patients in the magnitude of hundreds per region/country annually. As patient numbers increase, it is imperative to
begin looking ahead and develop an efcient strategy to put in place a supply chain
and logistic model that will meet the growing demand. Once the CAR-T cell drug
product is formulated, it is then assessed to ensure efcacy, product quality, safety,
and potency by Quality Control (QC) and Quality Assurance (QA). Depending on
the manufacturing facility, this process can either take place at the site of manufacturing or outsourced to a QC/QA third-party. Once successfully dispositioned, the
drug product is transported back to the clinical hospital where the cell drug product
can be infused back into the correct patient for treatment. The processes that need to
occur for this to happen need to be optimized, controlled, and regulated in a manner
that is right rst time [86].
For autologous CAR-T cell drug products, patient scheduling is key to ensuring
timely leukapheresis collection, manufacturing, product release and proper administration of the cell drug product for treatment. It is critical that the correct CAR-T
cell drug product be administered to the correct patient, thus highlighting the importance and need for systems that allow for proper sample tracking, documentation,
and patient identication. Recent development of software and digital tools, such as
cloud-based platforms and application programming interfaces, provides an efcient low-risk sample tracking and record keeping platform allowing disparate systems and information provided by key stakeholders to be seamlessly shared and
connected while keeping patient identity and data private [86]. Further optimization
and investigation are still required in developing automated systems that can ensure
chain of custody and identity is maintained throughout the entire CAR-T manufacturing process from leukapheresis all the way through to infusion of the cell drug
product into the correct patient. Shipping logistics need to be continuously evaluated including the design of cryo-shippers, temperature control mechanisms, and
couriers to provide shipment service to ensure integrity of the product and timely
delivery [42].
As the manufacturing process for CAR-T drug products is scaled up, important
factors inuencing the CAR-T cell drug product supply chain emerges. The logistic
model design for the manufacturing and distribution of cell products is one paramount factor to consider in determining the outlook of future CAR-T cell therapeutics. A simulation study of the centralized versus decentralized supply chain in the
UK has shown limited impact of both models on the total cost of treatment at scale;
9 CAR-T Bioprocessing
249
however, it concluded that decentralized supply chains (i.e., distributed point of care
manufacturing) may prove more efcient for larger geographical regions with some
constrained transport facilities [87]. Other factors to consider for scaling up the
production of CAR-T cells include allogeneic approaches where abundant cells are
retrieved from healthy donors and processed on a larger scale in a centralized manufacturing facility. However, due to the biological and repeatability concerns, this has
yet to be evaluated as a viable solution for the ease of access potential [88].
Designing highly personalized CAR-T cell therapeutics holds the most aspiring
potential of this technology, and scaling up this potential without using the allogeneic approaches, which would arguably limit this potential, remains a challenging
topic in the eld [89]. Considering the potential risks associated with such new
personalized therapeutic modalities, regulators often require intensive postmarketing evaluation of these therapeutics in patients for extended period of times
compared to traditional non-biologic therapeutics [90]. This in turn put some further
pressure on the logistics of such cellular-based therapies, and often requires novel
models of access to be considered [91]. Though the advancement in this eld is
quite substantial with therapies being developed from academic to industrial application within short periods of time, the scalability and affordability of these novel
therapeutics are the driving factors in determining their outlook as key tools in treating critical tumor conditions [92].
9.5 Considerations fortheCAR-T Field
As CAR-T therapies continue to progress in clinical trials, there are key challenges
that inhibit widespread adoption (summarized in Table9.4). One key challenge is
the cost of autologous CAR-T therapies. The current cost of approved CAR-T therapies ranges from $373,000 to 475,000 [93–96]. One approach to lowering the cost
of CAR-T therapies may be moving from autologous to allogeneic therapies. While
allogeneic therapies have their own specic challenges, including needing to establish a master bank that will not induce graft vs host disease, moving toward an “off
the shelf” adoptive cellular therapy may reduce costs [97] as a new drug product
batch is not needed for every individual patient, greatly reducing the number of
processing steps, logistical considerations, release testing required, and wait time
for the patient. Second, moving toward closed, automated production may reduce
costs of cellular therapies. An 8-day expansion process on the automated and closed
CliniMACS Prodigy is reported to cost $25,000, including labor and reagents [44].
Open systems that require frequent intervention by a highly trained labor force are
not only more costly than closed systems [98] but also more difcult to scale. It is
estimated that producing 10,000 cell therapy doses per year by open systems
requires 1700 full time employees across manufacturing, quality assurance, quality
control, and logistics [97]. Finally, it has been modeled that viral vector manufacturing is the costliest part of CAR-T therapy [98]. Any progress in reducing the cost of
viral vector, whether that be through improving vector potency or economizing