Introduction
Autologous T cell therapy has proven to be an effective treatment for
hematological malignancies, and there are currently six FDA approved
CAR-T therapies for the treatment of leukemia, lymphoma, and multiple
myloma (Albinger, Hartmann, & Ullrich, 2021; Costa et al., 2021; Ma et
al., 2019; Munshi et al., 2020). Developing effective therapeutics
against solid tumors represent an unmet need, and there are several
ongoing clinical trials using CAR-T or TCR-T cell therapies for solid
malignancies (Morotti et al., 2021). As promising as these personalized
T cell therapies are, manufacturing them is challenging due to the high
cost of goods manufactured (COGM), inability to scale, complex supply
chain logistics, long end-to-end time of bioprocessing plus release
testing, and limited patient access. Treating solid tumors presents
further challenges; not only must the dose be higher but the engineered
T cells must be equipped to penetrate and function within the tumor
microenvironment. Doses for solid tumors reach into the 100e8/CAR+ or
TCR+/kg cells(Mirzaei, Rodriguez, Shepphird, Brown, & Badie, 2017),
therefore a higher yield is required from the manufacturing process.
Additionally, producing cells with characteristics that will enable them
to home to the tumor site and attack cells expressing the tumor antigen
is necessary for an effective treatment.
Typical manufacturing processes for cell therapy rely on isolating white
blood cells from the patient through leukophoresis, followed by
enriching T cells from a leukopak using magnetic separation, activating
the cells with CD3 and CD28 activators, transducing with a viral vector
carrying the gene of interest in either static flasks or gas permeable
bags and expanding the T cells in a static vessel or rocking
bioreactor(Eyles et al., 2019). Many of these steps are open, requiring
the technician to handle the patient’s cells inside a biosafety cabinet
and use pipettes or syringes to transfer cells into vessels. Repeated
physical manipulation of the cells causes sheer stress and can
negatively impact cell viability, phenotype and overall fitness(Fowell
& Kim, 2021; Mastrogiovanni, Juzans, Alcover, & Di Bartolo, 2020). Due
to the high risk of contamination and inability to sterilize the final
drug product, these processes must be performed in an ISO 7 clean room.
It is also recommended that each patient have a dedicated incubator
which increases the manufacturing footprint(Sekiya et al., 2012).
Furthermore, each manufacturing step requires costly single-use
consumables, increasing COGM and impacting the environmental
sustainability as patient numbers increase.
We have developed a fully closed bioprocess for autologous T cell
therapies that eliminates the need for syringes, gas permeabilized bags,
and static incubators. Through integrating unit operations including
activation, transduction of leuko-apheresed cells, and cell expansion in
a rocking bioreactor, we achieved high transgene expression and desired
T cell yield sufficient for dose escalation studies for solid tumor
indications. This bioprocess provides a new approach for TCR-T cell
manufacturing resulting in a significant reduction in COGM compared to
the state-of-the-art T cell bioprocesses.