diff --git a/tex/thesis.tex b/tex/thesis.tex index 9f4778b..4bcbebd 100644 --- a/tex/thesis.tex +++ b/tex/thesis.tex @@ -581,14 +581,14 @@ modern manufacturing process. The goal of this dissertation was to develop a microcarrier-based \gls{dms} T cell expansion system and determine biologically-meaningful \glspl{cqa} and \glspl{cpp} that could be used to optimize for highly-potent T cells. In -\cref{aim1}, we develop and characterized the \gls{dms} system, including -quality control steps. We also demonstrate the feasibility of expanding -high-quality T cells. In \cref{aim2a,aim2b}, we use \gls{doe} methodology to -optimize the \gls{dms} platform, and we develop a computational pipeline to +\cref{aim1}, we developed and characterized the \gls{dms} system, including +quality control steps. We also demonstrated the feasibility of expanding +high-quality T cells. In \cref{aim2a,aim2b}, we used \gls{doe} methodology to +optimize the \gls{dms} platform, and we developed a computational pipeline to identify and model the effects of measurable \glspl{cqa} and \glspl{cpp} on the -final product. In \cref{aim3}, we demonstrate the effectiveness of the \gls{dms} -platform \invivo{}. This thesis lays the groundwork for a novel T cell expansion -method which can be utilized at scale for clinical trials and beyond. +final product. In \cref{aim3}, we demonstrated the effectiveness of the +\gls{dms} platform \invivo{}. This thesis lays the groundwork for a novel T cell +expansion method which can be utilized at scale for clinical trials and beyond. \clearpage @@ -604,39 +604,39 @@ diseases\cite{Fesnak2016,Rosenberg2015}. In 2017, Novartis and Kite Pharma received FDA approval for \textit{Kymriah} and \textit{Yescarta} respectively, two genetically-modified \gls{car} T cell therapies against B cell malignancies. Despite these successes, \gls{car} T cell therapies are constrained by an -expensive and difficult-to-scale manufacturing process with little control on -cell quality and phenotype\cite{Roddie2019, Dwarshuis2017}. State-of-the-art T -cell manufacturing techniques focus on \acd{3} and \acd{28} activation and -expansion, typically presented on superparamagnetic, iron-based microbeads -(Invitrogen Dynabead, Miltenyi MACS beads), on nanobeads (Miltenyi TransACT), or -in soluble tetramers (Expamer)\cite{Roddie2019,Dwarshuis2017,Wang2016, - Piscopo2017, Bashour2015}. These strategies overlook many of the signaling -components present in the secondary lymphoid organs where T cells expand -\invivo{}. Typically, T cells are activated under close cell-cell contact, which -allows for efficient autocrine/paracrine signaling via growth-stimulating -cytokines such as \gls{il2}. Additionally, the lymphoid tissues are comprised of -\gls{ecm} components such as collagen and stromal cells, which provide signals -to upregulate proliferation, cytokine production, and pro-survival +expensive, difficult-to-scale manufacturing process with little control on cell +quality and phenotype\cite{Roddie2019, Dwarshuis2017}. State-of-the-art T cell +manufacturing techniques focus on \acd{3} and \acd{28} activation and expansion, +typically presented on superparamagnetic, iron-based microbeads (Invitrogen +Dynabead, Miltenyi MACS beads), on nanobeads (Miltenyi TransACT), or in soluble +tetramers (Expamer)\cite{Roddie2019,Dwarshuis2017,Wang2016, Piscopo2017, + Bashour2015}. These strategies overlook many of the signaling components +present in the secondary lymphoid organs where T cells expand \invivo{}. +Typically, T cells are activated under close cell-cell contact, which allows for +efficient autocrine/paracrine signaling via growth-stimulating cytokines such as +\gls{il2}. Additionally, the lymphoid tissues are comprised of \gls{ecm} +components such as collagen and stromal cells, which provide signals to +upregulate proliferation, cytokine production, and pro-survival pathways\cite{Gendron2003, Ohtani2008, Boisvert2007, Ben-Horin2004}. A variety of solutions have been proposed to make the T cell expansion process -more physiological. Including feeder cell cultures\cite{Forget2014} and +more physiological. These include feeder cell cultures\cite{Forget2014} and biomaterials-based methods such as lipid-coated microrods or 3D scaffold gels\cite{Cheung2018,Delalat2017,meyer15_immun,Lambert2017} that attempt to recapitulate the cellular membrane, large interfacial contact area, 3D-structure, or soft surfaces T cells normally experience \invivo{}. While -these have been shown to activation and expand T cells, they either are not +these have been shown to activate and expand T cells, they either are not scalable (in the case of feeder cells) or still lack many of the signals and cues T cells experience as the expand. Additionally, none have been shown to preferentially expand highly-potent T cell necessary for anti-cancer therapies. -Such high potency cells including subtypes with low differentiation state such +Such high potency cells are subtypes with low differentiation state such as \gls{tscm} and \gls{tcm} cells or CD4 cells, all of which have been shown to be necessary for durable responses\cite{Xu2014, Fraietta2018, Gattinoni2011, Gattinoni2012,Wang2018, Yang2017}. Methods to increase memory and CD4 T cells in the final product are needed. Furthermore, \gls{qbd} principles such as discovering and validating novel \glspl{cqa} and \glspl{cpp} in the space of T cell manufacturing are required to reproducibly manufacture these subtypes and -ensure low-cost and safe products with maximal effectiveness in the clinic +ensure low-cost and safe products with maximal effectiveness in the clinic. This dissertation describes a novel \acrlong{dms}-based method derived from porous microcarriers functionalized with \acd{3} and \acd{28} \glspl{mab} for @@ -654,11 +654,11 @@ emulate the large contact surface area that occurs between T cells and \section*{hypothesis} The hypothesis of this dissertation was that using \glspl{dms} created from -off-the-shelf microcarriers and coated with activating \glspl{mab} would lead to -higher quantity and quality T cells as compared to state-of-the-art bead-based -expansion. We also hypothesized that T cells have measurable biological -signatures that are predictive of downstream outcomes and phenotypes. The -objective of this dissertation was to develop this platform, test its +off-the-shelf microcarriers and coated with activating \glspl{mab} would +increase quantity and quality of T cells as compared to state-of-the-art +bead-based expansion. We also hypothesized that such T cells have measurable +biological signatures that are predictive of downstream outcomes and phenotypes. +The objective of this dissertation was to develop this platform, test its effectiveness both \invitro{} and \invivo{}, and develop computational pipelines to discover novel \glspl{cpp} and \glspl{cqa} that can be translated to a manufacturing environment and a clinical trial setting. @@ -683,10 +683,10 @@ The specific aims of this dissertation are outlined in In this first aim, we demonstrated the process for manufacturing \glspl{dms}, including quality control steps that are necessary for translation of this -platform into a scalable manufacturing setting. We also demonstrate that the +platform into a scalable manufacturing setting. We also demonstrated that the \gls{dms} platform leads to higher overall expansion of T cells and higher overall fractions of potent memory and CD4+ subtypes desired for T cell -therapies. Finally, we demonstrate \invitro{} that the \gls{dms} platform can be +therapies. Finally, we showed \invitro{} that the \gls{dms} platform can be used to generate functional \gls{car} T cells targeted toward CD19. \subsection*{aim 2: develop methods to control and predict T cell quality} @@ -705,7 +705,7 @@ accomplished through two sub-aims: \subsection*{aim 3: confirm potency of T cells from novel T cell expansion process using \invivo{} xenograft mouse model} -In this final aim, we demonstrate the effectiveness of \gls{dms}-expanded T +In this final aim, we demonstrated the effectiveness of \gls{dms}-expanded T cells compared to state-of-the-art beads using \invivo{} mouse models for \gls{all}. @@ -732,27 +732,28 @@ manipulation\cite{Kirouac2008, Little2006, Pirnay2012, Rousseau2013}. This is further compounded by the lack of standardization and limited regulation. In order to overcome these barriers, adopting a systemic approach to cell -manufacturing using \acrlong{qbd} principles will be extremely +manufacturing using \acrfull{qbd} principles will be extremely important\cite{Kirouac2008}. In \gls{qbd}, the objective is to reproducibly manufacturing products which minimizes risk for downstream stakeholders (in this -case, the patient). Broadly, this entails determining \acrlongpl{cqa} and -\acrlongpl{cpp} and incorporating them into models which can explain and predict -the cell manufacturing process. +case, the patient). This entails determining \acrlongpl{cqa} and \acrlongpl{cpp} +and incorporating them into models which can explain and predict the cell +manufacturing process. -\Glspl{cqa} are measurable properties of the product that can be used to define -its functionality and hence quality. \glspl{cqa} are important for defining the -characteristics of a `good' product (release criteria) but also for ensuring +\Glspl{cqa} are measurable properties of the product that are used to define its +functionality and hence quality. \glspl{cqa} are important for defining the +characteristics of a ``good'' product (release criteria) but also for ensuring that a process is on track to making such a product (process control). In the space of cell manufacturing, examples of \glspl{cqa} include markers on the surface of cells and readouts from functional assays such as killing assays. In general, these are poorly understood if they exist at all. +%% TODO IL2 use here is wonky \glspl{cpp} are parameters which may be tuned and varied to control the outcome -of process and the quality of the final product. In cell manufacturing, these -are poorly understood. Examples in the cell manufacturing space include the type -of media used and the amount of \il{2} added. Once \glspl{cpp} are known, they -can be optimized to ensure that costs are minimized and potency of the cellular -product is maximized. +of process and the quality of the final product. Examples include the type of +media used and the amount of \il{2} added. While these can be easy to control, +the effect they have on the final outcome is generally unknown. Once \glspl{cpp} +are known, they can be optimized to ensure that costs are minimized and potency +of the cellular product is maximized. The topic of discovering novel \glspl{cpp} and \glspl{cqa} in the context of this work are discussed further in \cref{sec:background_doe} and @@ -767,12 +768,13 @@ theory the technology developed in this dissertation could theoretically apply to any T cell-based therapy with little to no modification. One of the first successful T cell-based immunotherapies against cancer is -\glspl{til}\cite{Rosenberg2015}. This method works by taking tumor specimens -from a patient, allowing the tumor-reactive lymphocytes to expand \exvivo{}, and -then administered back to the patient along with a high dose of -\il{2}\cite{Rosenberg1988}. In particular, \gls{til} therapy has shown robust -results in treating melanoma\cite{Rosenberg2011}, although \glspl{til} have been -found in other solid tumors such as gastointestinal, cervical, lung, and +\glspl{til}\cite{Rosenberg2015}. This method works by excising tumor fragments +from a patient, allowing the tumor-reactive lymphocytes to expand \exvivo{} from +within these fragments, and then administered these lymphocytes back to the +patient along with a high dose of \il{2}\cite{Rosenberg1988}. In particular, +\gls{til} therapy has shown robust results in treating +melanoma\cite{Rosenberg2011}, although \glspl{til} have been found in other +solid tumors such as gastointestinal, cervical, lung, and ovarian\cite{Rosenberg2015, Wang2014, Foppen2015, Solinas2017, June2007, Santoiemma2015}, and their presence is generally associate with favorable outcomes\cite{Clark1989}. \glspl{til} are heterogeneous cell mixtures and @@ -795,26 +797,27 @@ T cells with transduced \glspl{tcr} were first designed to overcome the limitations of \glspl{til}\cite{Rosenberg2015, Wang2014}. In this case, T cells are transduced \exvivo{} with a lentiviral vector to express a \gls{tcr} targeting a tumor antigen. T cells transduced with \glspl{tcr} have shown robust -results in melanoma patients\cite{Robbins2011}, synovial -sarcoma\cite{Morgan2006}, and others\cite{Ikeda2016}. To date, there are over -200 clinical trials using T cells with transduced \glspl{tcr}. +results against melanoma \cite{Robbins2011}, synovial sarcoma\cite{Morgan2006}, +and others\cite{Ikeda2016}. To date, there are over 200 clinical trials using T +cells with transduced \glspl{tcr}. While transduced \glspl{tcr} offer some flexibility in retargeting T cells toward relevant tumor antigens, they are still limited in that they can only -target antigens that are presented via \gls{mhc} complexes. \acrlong{car} T -cells overcome this limitation by using linking a \gls{tcr}-independent antigen -recognition domain with the stimulatory and costimulatory machinery of a T cell -\gls{car} T cells were first demonstrated in 1989, where the authors swapped the +target antigens that are presented via \gls{mhc}. \Acrlong{car} T cells overcome +this limitation by linking a \gls{tcr}-independent antigen recognition domain +with the stimulatory and costimulatory machinery of a T cell. \gls{car} T cells +were first demonstrated in 1989, where the authors swapped the antigen-recognition domains of a native \gls{tcr} with a that of a foreign \gls{tcr}\cite{Gross1989}. Since then, this method has progressed to using an -\gls{scfv} with a CD3$\upzeta$ stimulatory domain along with the CD28, OX-40, or -4-1BB domains for costimulation. Since these can all be expressed with one -protein sequence, \gls{car} T cells are relatively simple to produce and require -only a single genetic transduction step (usually a lentiviral vector) to -reprogram a batch T cells \exvivo{} toward the desired antigen. \gls{car} T -cells have primarily found success in against CD19- and CD20-expressing tumors -such as \gls{all} and \gls{cll} (eg B-cell malignancies)\cite{Kalos2011, - Brentjens2011, Kochenderfer2010, Maude2014, Till2012, Till2008}. +\gls{scfv} for antigen recognition, a CD3$\upzeta$ domain for the stimulatory +signal, and a CD28, OX-40, or 4-1BB domains for the costimulatory signal. Since +these can all be expressed with one protein sequence, \gls{car} T cells are +relatively simple to produce and require only a single genetic transduction step +(usually a lentiviral vector) to reprogram a batch T cells \exvivo{} toward the +desired antigen. \gls{car} T cells have primarily found success in against CD19- +and CD20-expressing tumors such as \gls{all} and \gls{cll} (eg B-cell +malignancies)\cite{Kalos2011, Brentjens2011, Kochenderfer2010, Maude2014, + Till2012, Till2008}. Out of all the T cell therapies discussed thus far, \gls{car} T cells have experienced the most commercial success and excitement. In 2017, Novartis and @@ -828,9 +831,8 @@ date, there are almost 1000 clinical trials using \gls{car} T cells. \subsection{Scaling T Cell Expansion} -In order to scale T cell therapies to meet clinical demands, automation and -bioreactors will be necessary. To this end, there are several choices that have -found success in the clinic. +In order to scale T cell therapies, automation and bioreactors will be +necessary. To this end, several choices have found success in the clinic. The WAVE bioreactor (GE Healthcare) is the choice of expansion for many clinical applications\cite{Brentjens2011, Hollyman2009, Brentjens2013}. It is part of a @@ -844,32 +846,30 @@ design, which could have negative impact on cross-talk, activation, and growth\cite{Somerville2012}. % BACKGROUND find clinical trials (if any) that use this -Alternatively, the CliniMACS Prodigy (Miltenyi) is an all-in-one system that is -a fully closed system that removes the need for expensive cleanrooms and -associated personnel\cite{Kaiser2015, Bunos2015}. It contains modules to perform -transduction, expansion, and washing. This setup also implies that fewer -mistakes and handling errors will be made, since many of the steps are internal -to the machine. Initial investigations have shown that it can yield T cells -doses required for clinical use\cite{Zhu2018}. At the time of writing, several -clinical trial are underway which use the CliniMACS, although mostly for -stem-cell based cell treatments. +Alternatively, the CliniMACS Prodigy (Miltenyi) is an all-in-one, fully-closed +system that removes the need for expensive cleanrooms and associated +personnel\cite{Kaiser2015, Bunos2015}. It contains modules to perform +transduction, expansion, and washing. This setup is less prone to mistakes, +since most steps are internal to the machine. Initial investigations have shown +that it can yield T cells doses required for clinical use\cite{Zhu2018}. At the +time of writing, several clinical trial are underway which use the CliniMACS, +although mostly for stem-cell based cell treatments. Finally, another option that has been investigated for T cell expansion is the Grex bioreactor (Wilson Wolf). This is effectively a tall tissue-culture plate -with a porous membrane at the bottom, which allows gas exchange to the active -cell culture at the bottom of the plate while permitting large volumes of media -to be loaded on top without suffocating the cells. While this is quite similar -to plates and flasks normally used for small-scale research, the important -difference is that its larger size requires fewer interactions and keeps the -cells at a higher nutrient concentration for longer periods of time. However, it -is still a an open system and requires manual (by default) interaction from an -operator to load, feed, and harvest the cell product. Grex bioreactors have been -using to grow \glspl{til}\cite{Jin2012} and virus-specific T -cells\cite{Gerdemann2011}. +with a porous membrane at the bottom. This allows large volumes of media to be +loaded without suffocating the cells, which can exchange gas through the +membrane. While this is quite similar to plates and flasks normally used for +small-scale research, the important difference is that its larger size requires +fewer interactions and keeps the cells at a higher nutrient concentration for +longer periods of time. However, it is still a an open system and requires +manual (by default) interaction from an operator to load, feed, and harvest the +cell product. Grex bioreactors have been using to grow \glspl{til}\cite{Jin2012} +and virus-specific T cells\cite{Gerdemann2011}. Much work is still required in the space of bioreactor design for T cell manufacturing, but novel T cell expansion technologies such as that described in -this work need to consider how it may be used at scale in such a system. +this work need to consider how they may be used at scale in such a system. \subsection{Cell Sources in T Cell Manufacturing}\label{sec:background_source} @@ -887,35 +887,34 @@ cross-reactivity with the patient and thus \gls{gvhd} is not a concern\cite{Decker2012}. However, there are numerous disadvantages. Autologous therapies are over 20 times more costly as the process needs to be repeated for every patient\cite{Harrison2019}. Compounding this, many cell products are -manufactured at a centralized location, so patient T cells need to be shipped -twice on dry ice from the hospital and back. This adds days to the process, -which is critical for patients with fast moving diseases. Manufacturing could be -done on-site in a decentralized manner, but this requires more equipment and -personnel overall. Using cells from a diseased patient has many drawbacks in -itself. Cancer patients (especially those with chronic illnesses) often have -exhausted T cells which expand far less readily and are consequently less -potent\cite{Wherry2015, Ando2019, Zheng2017}. Additionally, they may have high -frequencies of \glspl{treg} which inhibitory\cite{Decker2012}. Removing these -cells as well as purifying \glspl{th1} may enhance the potency of the final -product\cite{Goldstein2012, Drela2004, Rankin2003, Luheshi2013, Grotz2015}; -however, this would make the overall process more expensive as an additional -separation step would be required. +manufactured at a centralized location, so cells need to be shipped on dry ice +from the hospital and back. This adds days to the process, which is critical for +patients with fast moving diseases. Manufacturing could be done on-site in a +decentralized manner, but this requires more equipment and personnel overall. +Sourcing cells from a diseased patient has many drawbacks in itself. Cancer +patients (especially those with chronic illnesses) often have exhausted T cells +which expand far less readily and are consequently less potent\cite{Wherry2015, + Ando2019, Zheng2017}. Additionally, they may have high frequencies of +\glspl{treg} which have an inhibitory effect on +immunotherapies\cite{Decker2012}. Removing these cells as well as purifying +\glspl{th1} may enhance the potency of the final product\cite{Goldstein2012, + Drela2004, Rankin2003, Luheshi2013, Grotz2015}; however, this makes the +overall process more expensive as an additional separation step is required. Allogeneic T cell therapies overcome nearly all of these disadvantages. Donor \glspl{pbmc} are easy to obtain, they can be processed in centralized locations, -they can be stored easily under liquid nitrogen, and donors could be screened to -find those with optimal anti-tumor cells. The key is overcoming \gls{gvhd}. -Obviously this could be done the same way as done for transplants where patients -find a `match' for their \gls{hla} type, but this severally limits options. This -can be overcome by using advanced gene-editing tools which can both add and -delete genetic material (eg \glspl{zfn}, \glspl{talen}, or \gls{crispr}) to -remove the native \gls{tcr} which would prevent the donor T cells from attacking -host tissue\cite{Liu2019, Wiebking2020, Provasi2012, Berdien2014, Themeli2015}. -This obviously complicates the process, as additional edits besides the -insertion of the \gls{car} would be required, and these technologies are not yet -very efficient. To date there are about 10 open clinical trials utilizing -allogeneic T cell therapies edited with \gls{crispr} to reduce the likelihood of -\gls{gvhd}. +and they can be stored easily under liquid nitrogen. Donors can also be screened +to find those with optimal anti-tumor cells. The key is overcoming \gls{gvhd}. +Obviously this could be done analogously to transplants where patients find a +``match'' for their \gls{hla} type, but this severally limits options. This can +be overcome by using advanced gene-editing tools (eg \glspl{zfn}, \glspl{talen}, +or \gls{crispr}) to remove the native \gls{tcr} and thus prevent the donor T +cells from attacking host tissue\cite{Liu2019, Wiebking2020, Provasi2012, + Berdien2014, Themeli2015}. This obviously complicates the process, as +additional edits besides the insertion of the \gls{car} would be required, and +these technologies are not yet very efficient. To date there are about 10 open +clinical trials utilizing allogeneic T cell therapies edited with \gls{crispr} +to reduce the likelihood of \gls{gvhd}. \subsection{Overview of T Cell Quality}\label{sec:background_quality} @@ -927,13 +926,13 @@ criteria, and initial cell source screening. One of the most important dimensions of T cell quality is that of differentiation. T cells begin their life in circulation (eg after they exit the -thymus) as \glspl{tn}. When they become activated in the secondary lymph node +thymus) as \glspl{tn}. When they become activated in the secondary lymphoid organs, they differentiate from \gls{tn} to \glspl{tscm}, \glspl{tcm}, \glspl{tem}, and finally \glspl{teff}\cite{Gattinoni2012}. Subtypes earlier in -this process are generally called `memory' or `memory-like' cells (eg \gls{tscm} -and \gls{tcm}), and have been shown to have increased potency toward a variety -of tumors, presumably due to their higher capacity for self-renewal and -replication, enhanced migratory capacity, and/or increased engraftment +this process are generally called ``memory'' or ``memory-like'' cells (eg +\gls{tscm} and \gls{tcm}), and have been shown to have increased potency toward +a variety of tumors, presumably due to their higher capacity for self-renewal +and replication, enhanced migratory capacity, and/or increased engraftment potential\cite{Xu2014, Gattinoni2012, Fraietta2018, Gattinoni2011, Turtle2009}. The capacity for self-renewal is especially important for T cells therapies, as evidenced by the fact that \gls{til} therapies with longer telomeres tend to @@ -951,7 +950,7 @@ In addition to memory, the other major axis by which T cells may be classified is the CD4/CD8 ratio. \Glspl{th} are CD4+ are responsible for secreting cytokines which coordinate the immune response while CD8+ \glspl{tc} are responsible for killing tumors or infected cells using specialized lytic -enzymes. Since \glspl{tc} actually perform the killing function, it seems +enzymes. Since \glspl{tc} actually possess the killing function, it seems intuitive that \glspl{tc} would be most important for anti-tumor immunotherapies. However, in mouse models with glioblastoma, survival was negatively impacted when \glspl{th} were removed\cite{Wang2018}. Furthermore, @@ -969,10 +968,10 @@ radioactive tracer, by measuring the degranulation of the T cells themselves, or by measuring a cytokine that is secreted upon T cell activation and killing such as \gls{ifng}. Furthermore, the viability of T cells may be assessed using a number of methods, including exclusion dyes such as \gls{aopi} or a functional -assay to detect metabolism. Finally, for the purposes of safety, T cell products -using retro- or lentiviral vectors as their means of gene-editing must be tested -for replication competent vectors\cite{Wang2013} and for contamination via -bacteria or other pathogens. +assay to detect metabolism. Finally, for safety, retro- or lentivirally +transduced T cell products must be tested for replication competent +vectors\cite{Wang2013}, and all cell products in general should be tested for +bacterial or fungal contamination. \subsection{T Cell Activation Methods}\label{sec:background_activation} @@ -983,24 +982,23 @@ present a peptide via \gls{mhc} that the T cell in question is able to recognize. Signal 2 is administered via CD80 and CD86 which are also present on \glspl{apc} and is necessary to prevent the T cell from becoming anergic. While these two signal are the bare minimum to trigger a T cell to expand, there are -many other potential signals present. T cells have many other costimulatory -receptors such as OX40, 4-1BB and ICOS which are costimulatory along with CD28, -and \glspl{apc} have corresponding ligands for these depending on the nature of -the pathogen they have detected\cite{Azuma2019}. Furthermore, T cells exist in -high cell density within the secondary lymphoid organs, which allows efficient -cytokine cross-talk in an autocrine and paracrine manner. These cytokines are -responsible for triggering proliferation (in the case of \il{2}) and subset -differentiation (in the case of many others)\cite{Luckheeram2012}. By tuning the -signal strength and duration of Signal 1, Signal 2, the various costimulatory -signals, and the cytokine milieu, a variety of T cell phenotypes can be -actualized. +many other potential signals present. T cells have other receptors such as OX40, +4-1BB, and ICOS which are costimulatory along with CD28, and \glspl{apc} have +corresponding ligands for these depending on the nature of the pathogen they +have detected\cite{Azuma2019}. Furthermore, T cells exist in high cell density +within the secondary lymphoid organs, which allows efficient cytokine cross-talk +in an autocrine and paracrine manner. These cytokines are responsible for +triggering proliferation (in the case of \il{2}) and subset differentiation (in +the case of many others)\cite{Luckheeram2012}. By tuning the signal strength and +duration of Signal 1, Signal 2, the various costimulatory signals, and the +cytokine milieu, a variety of T cell phenotypes can be actualized. -\Invitro{}, T cells can be activated in a number of ways but the simplest and -most common is to use \glspl{mab} that cross-link the CD3 and CD28 receptors, -which supply Signal 1 and Signal 2 without the need for antigen (which also -means all T cells are activated and not just a few specific clones). Additional -signals may be supplied in the form of cytokines (eg \il{2}, \il{7}, or \il{15}) -or feeder cells\cite{Forget2014}. +There are many ways to activate T cells \invitro{}, but the simplest and most +common is to use \glspl{mab} that cross-link CD3 and CD28, which supply Signal 1 +and Signal 2 without the need for antigen (which also means all T cells are +activated and not just a few specific clones). Additional signals may be +supplied in the form of cytokines (eg \il{2}, \il{7}, or \il{15}) or feeder +cells\cite{Forget2014}. As this is a critical unit operation in the manufacturing of T cell therapies, a number of commercial technologies exist to activate T cells\cite{Wang2016, @@ -1009,11 +1007,11 @@ number of commercial technologies exist to activate T cells\cite{Wang2016, accomplished in a \gls{gmp} manner (at least from a reagents perspective) as soluble \gls{gmp}-grade \glspl{mab} are commericially available. A similar but distinct method along these lines is to use multivalent activators such as -ImmunoCult (StemCell Technologies) or Expamer (Juno Therapeutics) which may have +ImmunoCult (StemCell Technologies) or Expamer (Juno Therapeutics) which have increased cross-linking capacity compared to traditional \glspl{mab}. Beyond soluble protein, \glspl{mab} against CD3 and CD28 can be mounted on magnetic microbeads (\SIrange{3}{5}{\um} in diameter) such as DynaBeads (Invitrogen) and -MACSbeads (\miltenyi{}), which are easier to separate using magnetic washing +MACSbeads (\miltenyi{}), which are easy to separate using magnetic washing plates. Magnetic nanobeads such as TransAct (\miltenyi{}) work by a similar principle except they can be removed via centrifugation rather than a magnetic washing plate. Cloudz (RnD Systems) are another bead-based T cell expansion @@ -1026,18 +1024,17 @@ Signal 1 and Signal 2 and ignore the many other physiological cues present in the secondary lymphoid organs. A variety of novel T cell activation and expansion solutions have been proposed to overcome this. One strategy is to use modified feeder cell cultures to provide activation signals similar to those of -\glspl{dc}\cite{Forget2014}. While this has the theoretical capacity to mimic -several key components of the lymph node, it is hard to reproduce on a large -scale due to the complexity and inherent variability of using cell lines in a -fully \gls{gmp}-compliant manner. Others have proposed biomaterials-based -solutions to circumvent this problem, including lipid-coated -microrods\cite{Cheung2018}, 3D-scaffolds via either Matrigel\cite{Rio2018} or -3d-printed lattices\cite{Delalat2017}, ellipsoid beads\cite{meyer15_immun}, and -\gls{mab}-conjugated \gls{pdms} beads\cite{Lambert2017} that respectively -recapitulate the cellular membrane, large interfacial contact area, -3D-structure, or soft surfaces T cells normally experience \textit{in vivo}. -None have been demonstrated to demonstrably expand high quality T cells as -outlined in \cref{sec:background_quality}. +\glspl{dc}\cite{Forget2014}. While this can theoretically mimic many components +of the lymph node, it is hard to scale due to the complexity and inherent +variability of using cell lines in a \gls{gmp}-compliant manner. Others have +proposed biomaterials-based solutions to circumvent this problem, including +lipid-coated microrods\cite{Cheung2018}, 3D-scaffolds via either +Matrigel\cite{Rio2018} or 3d-printed lattices\cite{Delalat2017}, ellipsoid +beads\cite{meyer15_immun}, and \gls{mab}-conjugated \gls{pdms} +beads\cite{Lambert2017} that respectively recapitulate the cellular membrane, +large interfacial contact area, 3D-structure, or soft surfaces T cells normally +experience \textit{in vivo}. None of these have been shown to expand high +quality T cells as outlined in \cref{sec:background_quality}. \subsection{Microcarriers in Bioprocessing} @@ -1046,56 +1043,54 @@ methods described in \cref{sec:background_activation}. Microcarriers have historically been used to grow a number of adherent cell types for a variety of applications. They were introduced in 1967 as a means to -grow adherent cells `in suspension', effectively turning a 2D flask system into -a 3D culture system\cite{WEZEL1967}. Microcarriers are generally spherical and -are several hundred \si{\um} in diameter, which means they collectively have a -much higher surface area than a traditional flask when matched for volume. +grow adherent cells ``in suspension,'' effectively turning a 2D flask into a 3D +culture system\cite{WEZEL1967}. Microcarriers are generally spherical and are +several hundred \si{\um} in diameter, which means they collectively have a much +higher surface area than a traditional flask when matched for volume. Consequently, this means that microcarrier-based cultures can operate with much -lower footprints than flask-like systems. Microcarriers also allow cell culture -to operate more like a traditional chemical engineering process, wherein a -\gls{cstr} may be employed to enhance oxygen transfer, maintain pH, -and continuously supply nutrients\cite{Derakhti2019}. +lower footprints than flask-like systems. Microcarriers also allow cell cultures +to operate more like traditional chemical engineering processes, wherein a +\gls{cstr} may be employed to enhance oxygen transfer, maintain pH, and +continuously supply nutrients\cite{Derakhti2019}. A variety of microcarriers have been designed, primarily differing in their -choice of material and macroporous structure. Key concerns driving these -choiceshave been cell attachment at the beginning of culture and cell detachment -at the harvesting step\cite{Derakhti2019}. Many microcarriers simply use -polystyrene (the material used for tissue culture flasks and dishes in general) -with no modification (SoloHill Plastic, Nunc Biosilon), with a cationic surface -charge (SoloHill Hillex) or coated with an \gls{ecm} protein such as collagen -(SoloHill Fact III). Other base materials have been used such as dextran (GE -Healthcare Cytodex), cellulose (GE Healthcare Cytopore), and glass (\sigald{} -G2767), all with none or similar surface modifications. Additionally, some -microcarriers such as \gls{cus} and \gls{cug} are composed entirely out of -protein (in these cases, porcine collagen) which also allows the microcarriers -to be enzymatically degraded. In the case of non-protein materials, cells may -still be detached using enzymes but these require similar methods to those -currently used in flasks such as trypsin which target the cellular \gls{ecm} -directly. Since trypsin and related enzymes tends to be harsh on cells, an -advantage of using entirely protein-based microcarriers is that they can be -degraded using a much safer enzyme such as collagenase, at the cost of being -more expensive and also being harder to make -\gls{gmp}-compliant\cite{Derakhti2019}. Going one step further, some -microcarriers are composed of a naturally degrading scaffold such as alginate, -which do not need an enzyme for degradation. Finally, microcarriers can differ -in their overall structure. \gls{cug} and \gls{cus} microcarriers as well as the -Cytopore microcarriers are macroporous, meaning they have a porous network in -which cells can attach throughout their interior. This drastically increases the -effective surface area and consequently the number of cells which may be grown -per unit volume. Other microcarriers are microporous (eg only to small -molecules) or not porous at all (eg polystyrene); in either case the cells can -only grow on the surface. +choice of material and macroporous structure. Key concerns driving these choices +have been cell attachment at the beginning of culture and cell detachment at the +harvesting step\cite{Derakhti2019}. Many microcarriers simply use polystyrene +(the material used for tissue culture flasks and dishes in general) with no +modification (SoloHill Plastic, Nunc Biosilon), with a cationic surface charge +(SoloHill Hillex) or coated with an \gls{ecm} protein such as collagen (SoloHill +Fact III). Other base materials have been used such as dextran (GE Healthcare +Cytodex), cellulose (GE Healthcare Cytopore), and glass (\sigald{} G2767), all +with similar surface modifications (if any). Additionally, some microcarriers +such as \gls{cus} and \gls{cug} are composed entirely out of protein (in these +cases, porcine collagen) which also allows the microcarriers to be enzymatically +degraded. In the case of non-protein materials, cells may still be detached +using enzymes but these require similar methods to those currently used in +flasks such as trypsin which target the cellular \gls{ecm} directly. Since +trypsin and related enzymes tends to be harsh on cells, an advantage of using +entirely protein-based microcarriers is that they can be degraded using a much +safer enzyme such as collagenase, at the cost of being more expensive and also +being harder to make \gls{gmp}-compliant\cite{Derakhti2019}. Going one step +further, some microcarriers are composed of a naturally degrading scaffold such +as alginate, which do not need an enzyme for degradation. Finally, microcarriers +can differ in their overall structure. \gls{cug} and \gls{cus} microcarriers as +well as the Cytopore microcarriers are macroporous, meaning they have a porous +network in which cells can attach throughout their interior. This drastically +increases the effective surface area and consequently the number of cells which +may be grown per unit volume. Other microcarriers are microporous (eg only +permeable to small molecules) or not porous at all; in either case, cells can +only grow on the outer surface. -Microcarriers in general have seen the most use in growing \gls{cho} cells and -hybridomas in the case of protein manufacturing (eg \gls{igg} -production)\cite{Xiao1999, Kim2011} as well as \glspl{esc} and \glspl{msc} more -recently in the case of cell manufacturing\cite{Heathman2015, Sart2011, - Chen2013, Schop2010, Rafiq2016}. Interestingly, some groups have even explored -using biodegradable microcarriers \invivo{} as a delivery vehicle for stem cell -therapies in the context of regenerative medicine\cite{Zhang2016, Saltz2016, - Park2013, Malda2006}. However, the characteristic shared by all the cell types -in this application is the fact that they are adherent. In this work, we explore -the use of microcarrier for T cells, which are naturally non-adherent. +Microcarriers have been mainly used for growing \gls{cho} cells and hybridomas +in the case of protein manufacturing (eg \gls{igg} production)\cite{Xiao1999, + Kim2011} as well as \glspl{esc} and \glspl{msc} more recently in the case of +cell manufacturing\cite{Heathman2015, Sart2011, Chen2013, Schop2010, Rafiq2016}. +Interestingly, some groups have even explored using biodegradable microcarriers +\invivo{} as a delivery vehicle for stem cell therapies in the context of +regenerative medicine\cite{Zhang2016, Saltz2016, Park2013, Malda2006}. However, +all these cell types are adherent. In this work, we explore the use of +microcarrier for T cells, which are naturally non-adherent. The microcarriers used in this work were \gls{cus} and \gls{cug} (mostly the former) which are both composed of cross-linked gelatin and have a macroporous @@ -1119,7 +1114,7 @@ T cells naturally expand in the lymph nodes which have an \gls{ecm} composed of collagen\cite{Dustin2001, Ebnet1996, Ohtani2008}. Despite this, T cells don't interact with collagen fibers in the lymph node as the collagen fibers are sheathed with stromal fibroblasts\cite{Dustin2001, Ebnet1996}. However, the -\gls{ecm} of peripheral tissues is dense with exposed collagen fibers are +\gls{ecm} of peripheral tissues is dense where exposed collagen fibers are available to interact with T cells. Furthermore, T cells have been shown \invitro{} to crawl along collagen fibers in the presence of \glspl{apc}, facilitating short encounters with \glspl{apc}\cite{Gunzer2000}. While this may @@ -1129,16 +1124,15 @@ not be ideal \invivo{} due to the lack of cumulative signal received by The major surface receptors for collagen are \gls{a2b1} and \gls{a2b2}\cite{Dustin2001, Hemler1990}. These receptors are not expressed on -naive T cells and thus presence and stimulation of collagen alone is not -sufficient to cause activation or expansion of T cells\cite{Hemler1990}. These -receptors have been shown to lead to a number of functions that may be useful in -the context of T cell expansion. First, they have been shown to act in a -costimulatory manner which leads to increased proliferation\cite{Rao2000}. -Furthermore, \gls{a2b1} and \gls{a2b2} have been shown to protect Jurkat cells -against Fas-mediated apoptosis in the presence of collagen I\cite{Aoudjit2000, - Gendron2003}. Finally, these receptors have been shown to increase \gls{ifng} -production \invitro{} when T cells derived from human \glspl{pbmc} are -stimulated in the presence of collagen I\cite{Boisvert2007}. +naive \gls{tn} cells and thus presence and stimulation of collagen alone is not +sufficient for activation or expansion\cite{Hemler1990}; however, they have been +shown to possess many functions that may be useful for T cell expansion. First, +they can act in a costimulatory manner which leads to increased +proliferation\cite{Rao2000}. Furthermore, \gls{a2b1} and \gls{a2b2} seem to +protect Jurkat cells against Fas-mediated apoptosis in the presence of collagen +I\cite{Aoudjit2000, Gendron2003}. Finally, these receptors can increase +\gls{ifng} production \invitro{} when T cells derived from human \glspl{pbmc} +are stimulated in the presence of collagen I\cite{Boisvert2007}. \subsection{The Role of IL15 in Memory T Cell Proliferation} @@ -1148,8 +1142,8 @@ further exploration in \cref{aim2b}. Functionally, mice lacking the gene for either \il{15}\cite{Kennedy2000} or its high affinity receptor \il{15R$\upalpha$}\cite{Lodolce1998} are generally -healthy but show a deficit in memory CD8 T cells, thus underscoring its -importance in manufacturing high-quality memory T cells for immunotherapies. T +healthy but show a deficit in memory CD8 T cells, thus underscoring this +cytokine's importance in producing memory T cells for immunotherapies. T cells themselves express \il{15} and all of its receptor components\cite{MirandaCarus2005}. Additionally, blocking \il{15} itself or \il{15R$\upalpha$} \invitro{} has been shown to inhibit homeostatic @@ -1158,20 +1152,20 @@ proliferation of resting human T cells\cite{MirandaCarus2005}. % ACRO fix the il2R and IL15R stuff \il{15} has been puzzling historically because it shares almost the same pathway as \il{2} yet has different functions\cite{Stonier2010, Osinalde2014, Giri1994, - Giri1995}. In particular, both cytokines share the common $\upgamma$ subchain -(CD132) as well as the \il{2} $\upbeta$ receptor (CD122). The main difference in -the heterodimeric receptors for \il{2} and \il{15} is the \il{2} $\upalpha$ -receptor (CD25) and the \il{15} $\upalpha$ chain respectively, both of which -have high affinity for their respective ligands. The \il{2R$\upalpha$} chain -itself does not have any signaling capacity, and therefore all the signaling -resulting from \il{2} is mediated thought the $\upbeta$ and $\upgamma$ chains, -namely via JAK1 and JAK3 leading to STAT5 activation consequently T cell -activation. \il{15R$\upalpha$} itself has some innate signaling capacity, but -this is poorly characterized in lymphocytes\cite{Stonier2010}. Thus there is a -significant overlap between the functions of \il{2} and \il{15} due to their -receptors sharing the $\upbeta$ and $\upgamma$ chains in their heterodimeric -receptors, and perhaps the main driver of their differential functions it the -half life of each respective receptor\cite{Osinalde2014}. + Giri1995}. In particular, both cytokines bond with heterotrimeric receptors +which share the common $\upgamma$ subchain (CD132) as well as the \il{2} +$\upbeta$ receptor (CD122). The difference is the third subchain which is either +the \il{2} $\upalpha$ receptor (CD25) or the \il{15} $\upalpha$ chain +respectively, both of which have high affinity for their respective ligands. The +\il{2R$\upalpha$} chain itself does not have any signaling capacity, and +therefore all the signaling resulting from \il{2} is mediated thought the +$\upbeta$ and $\upgamma$ chains (namely via JAK1 and JAK3, which leads to STAT5 +activation, which leads to T cell activation). \il{15R$\upalpha$} itself has +some innate signaling capacity, but this is poorly characterized in +lymphocytes\cite{Stonier2010}. Thus there is a significant overlap between the +functions of \il{2} and \il{15} due to their receptors sharing the $\upbeta$ and +$\upgamma$ chains, and perhaps the main driver of their differential functions +it the half life of each respective receptor\cite{Osinalde2014}. Where \il{15} is unique is that many (or possibly most) of its functions derive from being membrane-bound to its receptor\cite{Stonier2010}. Particularly, @@ -1186,18 +1180,18 @@ mechanism is that cells expression \il{15R$\upalpha$} either need to express proximity require the $\upbeta$ and $\upgamma$ chains to receive the signal. In addition to \textit{trans} presentation, \il{15} may also work in a \textit{cis} manner, where \il{15R$\upalpha$}/\il{15} complexes may bind to the $\upbeta$ and -$\upgamma$ chains on the same cell, assuming all receptors are expressed and -soluble \il{15} is available\cite{Olsen2007}. Finally, \il{15R$\upalpha$} itself can exist in -a soluble form, which can bind to \il{15} and signal to cells which are not -adjacent to the source independent of the \textit{cis/trans} mechanisms already -described\cite{Budagian2004}. +$\upgamma$ chains on the same cell, assuming each subchain is expressed and +soluble \il{15} is available\cite{Olsen2007}. Finally, \il{15R$\upalpha$} itself +can exist in soluble form, which can bind to \il{15} and signal to cells which +are not adjacent to the source independent of the \textit{cis/trans} mechanisms +already described\cite{Budagian2004}. \subsection{Overview of Design of Experiments}\label{sec:background_doe} -The \gls{dms} system described in this dissertation has a number of parameters -that can be optimized and controlled (eg \glspl{cpp}). A \gls{doe} is an ideal -framework to test multiple parameters simultaneously and determine which are -relevant \glspl{cpp}. +The \gls{dms} system described in this dissertation has many parameters that can +be optimized and controlled (eg \glspl{cpp}). A \gls{doe} is an ideal framework +to test multiple parameters simultaneously and determine which are relevant +\glspl{cpp}. The goal of \gls{doe} is to answer a data-driven question with the least number of resources\cite{Wu2009}. It was developed in many non-biological industries @@ -1206,30 +1200,33 @@ industries where engineers needed to minimize downtime and resource consumption on full-scale production lines. At its core, a \gls{doe} is simply a matrix of conditions to test where each row -(usually called a `run') corresponds to one experimental unit for which the -conditions are applied, and each column represents a parameter of concern to be -tested. The values in each cell represent the level at which each parameter is -to be tested. When the experiment is performed using this matrix of conditions, -the results are be summarized into one or more `responses' that correspond to -each run. These responses are then be modeled (usually using linear regression) -to determine the statistic relationship (also called an `effect') between each -parameter and the response(s). +(usually called a ``run,'' which is the term used throughout this work) +corresponds to one experimental unit for which the conditions are applied, and +each column represents a parameter of concern to be tested. The values in each +cell represent the level of each parameter. When the experiment is performed +using this matrix of conditions, the results are be summarized into one or more +``responses'' that correspond to each run. These responses are then be modeled +(usually using linear regression) to determine the statistical relationship +(also called an ``effect'') between each parameter and the response(s). Collectively, the space spanned by all parameters at their feasible ranges is -commonly referred to as the `design space', and generally the goal of a +commonly referred to as the ``design space'', and generally the goal of a \gls{doe} is to explore this design space using using the least number of runs possible. While there are many types of \glspl{doe} depending on the nature of the parameters and the goal of the experimenter, they all share common principles: \begin{description} -\item [randomization --] The order in which the runs are performed should - ideally be as random as possible. This is to mitigate against any confounding - factors that may be present which depend on the order or position of the runs. - For an example in context, the evaporation rate of media in a tissue culture - plate will be much faster at the perimeter of the plate vs the center. While - randomization does not eliminate this error, it will ensure the error is - `spread' evenly across all runs in an unbiased manner. +\item [randomization --] The order in which the runs are performed should be + randomized. This is to guarantee that the tested parameters are independent of + any unobserved influences to the response, and thus allows the causal effect + of each parameter to be isolated completely\footnote{this is why \glspl{doe} + are sometimes called ``black box models;'' one can can safely say ``this + parameter causes that'' without paying attention to the causal structure of + the experiment}. For an example in context, the evaporation rate of media in + a tissue culture plate will be much faster at the perimeter of the plate vs + the center. While randomization does not eliminate this error, it will ensure + the error is ``spread'' across all runs in an unbiased manner. \item [replication --] Since the analysis of a \gls{doe} is inherently statistical, replicates should be used to ensure that the underlying distribution of errors can be estimated. While this is not strictly necessary @@ -1237,7 +1234,7 @@ principles: strong assumptions about the model structure (particularly in the case of high-complexity models which could easily fit the data perfectly) and also precludes the use of statistical tests such as the lack-of-fit test which can - be useful in rejecting or accepting a particular analysis. Note that the + be useful in rejecting or accepting a particular model. Note that the subject of replication is within but not the same as power analysis, which concerns the number of runs required to estimate a certain effect size. \item [orthogonality --] Orthogonality refers to the independence of each @@ -1249,14 +1246,15 @@ principles: experiments with many categorical variables) strategies exist to maximize orthogonality. \item [blocking --] In the case where the experiment must be non-randomly spread - over multiple groups, runs are assigned to `blocks' which are not necessarily - relevant to the goals of the experiment but nonetheless could affect the - response. A key assumption that is (usually) made in the case of blocking is - that there is no interaction between the blocking variable and any of the - experimental parameters. For example, in T cell expansion, if media lot were a - blocking variable and expansion method were a parameter, we would by default - assume that the effect of the expansion method does not depend on the media - lot (even if the media lot itself might change the mean of the response). + over multiple groups, runs are assigned to ``blocks'' which are not + necessarily relevant to the goals of the experiment but nonetheless could + affect the response. A key assumption that is (usually) made in the case of + blocking is that there is no interaction between the blocking variable and any + of the experimental parameters. For example, in T cell expansion, if media lot + were a blocking variable and expansion method were a parameter, we would by + default assume that the effect of the expansion method does not depend on the + media lot (even if the media lot itself might change the mean of the + response). \end{description} \Glspl{doe} served three purposes in this dissertation. First, we used them as @@ -1279,28 +1277,26 @@ investigated. However, it could be the case that one already has data on many of the factors of concern. If one only cares about main effects, performing a \gls{doe} (particularly a lower-powered screening experiment such as a resolution III design) with these factors and a few others may not be -productive, and one is better off performed a few extra pilot experiments before -doing a more complex design such as a central composite if desired. Furthermore, -it should be noted that while the goal of a \gls{doe} is to minimize resources, -the size necessary to justify a \gls{doe} may not be worth the experimental -return. For biological work (or any domain with little automation), performing a -randomized experiment with 20 to 30 runs is not trivial from a logistical -perspective, especially when considering the number of manual manipulations and -the chance of human error. +productive, and one is better off performing a few extra pilot experiments +before doing a more complex design such as a central composite if desired. +Furthermore, it should be noted that while the goal of a \gls{doe} is to +minimize resources, the size necessary to justify a \gls{doe} may not be worth +the experimental return. For biological work (or any domain with little +automation), performing a randomized experiment with 20 to 30 runs is not +trivial from a logistical perspective, especially when considering the number of +manual manipulations and the chance of human error. Despite these caveats, many of the principles used for a \gls{doe} are important in general for experimentation. The most obvious is randomization, which is -often not employed (and also not explicitly mentioned in papers) even though it -is empirically obvious that well plates have different evaporation rates -depending on well position. Assuming the experiment is manual, the largest -reason to avoid randomization is that the experimentalist has no pattern to -follow when administering treatment (such as ``add X to row 1 in well plate''), -thus cognitive burden and the likelihood of mistakes increases. While -\glspl{doe} are usually bigger with more parameters, the one-factor-at-a-time -experiment usually performed in biological disciplines is much smaller and only -has a few parameters, thus these concerns are minimal. There is no reason to -avoid randomization in these cases, as the added cognitive cost is far offset by -the guarantee of eliminated bias due to run position. +often not employed (and also not explicitly mentioned in papers). Assuming the +experiment is manual, the largest reason to avoid randomization is that the +experimentalist has no pattern to follow when administering treatment (such as +``add X to row 1 in well plate''), thus cognitive burden and the likelihood of +mistakes increases. While \glspl{doe} are usually bigger with more parameters, +the one-factor-at-a-time experiment usually performed in biological disciplines +is much smaller and only has a few parameters, thus these concerns are minimal. +There is no reason to avoid randomization in these cases, as the added cognitive +cost is far offset by the guarantee of eliminated bias due to run position. \subsection{Identification and Standardization of CPPs and CQAs}\label{sec:background_cqa} @@ -1315,15 +1311,15 @@ secrete numerous cytokines and metabolites in the media, which may reflect the internal state accurately and thus serve as a potential set of \glspl{cqa}. The complexity of these pathways dictates that we take a big-data approach to -this problem. To this end, there are several pertinent multi-omic (or simply -`omic') techniques that can be used to collect such datasets, which can then be -mined, modeled, and correlated to relevent responses (such as an endpoint -quantification of memory T cells) to identify pertinent \glspl{cqa}. +this problem. To this end, there are several multi-omic (or simply ``omic'') +techniques that can be used to collect such datasets, which can then be fit to +relevent responses (such as an endpoint quantification of memory T cells) to +identify pertinent \glspl{cqa}. An overview of the techniques used in this work are: \begin{description} -\item[Luminex --] This is a multiplexed bead-based assay similar to \gls{elisa} that can measure +\item[luminex --] This is a multiplexed bead-based assay similar to \gls{elisa} that can measure many bulk (not single cell) cytokine concentrations simultaneously in a media sample. This is a destructive assay but does not require cells to obtain a measurement. @@ -1333,7 +1329,7 @@ An overview of the techniques used in this work are: oxidation\cite{Buck2016, van_der_Windt_2012}. \gls{nmr} is a technique that can non-destructively quantify small molecules in a media sample, and thus is an attractive method that could be used for inline, real-time monitoring. -\item[Flow and Mass Cytometry --] Flow cytometry using fluorophores has been +\item[flow and mass cytometry --] Flow cytometry using fluorophores has been used extensively for immune cell analysis, but has a practical limit of approximately 18 colors\cite{Spitzer2016}. Mass cytometry is analogous to traditional flow cytometry except that it uses heavy-metal \gls{mab} @@ -1359,11 +1355,11 @@ interesting cell types and the markers that define them. Ultimately, identifying \glspl{cqa} will likely be an iterative process, wherein putative \glspl{cqa} will be identified, the corresponding \glspl{cpp} will be -set and optimized to maximize products with these \glspl{cpp}, and then -additional data will be collected in the clinic as the product is tested on -various patients with different indications. Additional \glspl{cqa} may be -identified which better predict specific clinical outcomes, which can be fed -back into the process model and optimized again. +set to maximize high-quality products, and then additional data will be +collected in the clinic as the product is tested on various patients with +different indications. Additional \glspl{cqa} may be identified which better +predict specific clinical outcomes, which can be fed back into the process model +and optimized again. \section{Innovation} @@ -1373,7 +1369,7 @@ novel considering the state-of-the-art technology for T cell manufacturing: \begin{itemize} \item \Glspl{dms} offers a compelling alternative to state-of-the-art magnetic bead technologies (e.g. DynaBeads, MACS-Beads), which is noteworthy because - the licenses for these techniques is controlled by only a few companies + the licenses for these techniques are controlled by only a few companies (Invitrogen and Miltenyi respectively). Because of this, bead-based expansion is more expensive to implement and therefore hinders companies from entering the rapidly growing T cell manufacturing arena. Providing an alternative will @@ -1381,7 +1377,7 @@ novel considering the state-of-the-art technology for T cell manufacturing: lower costs, and higher innovation in the T cell manufacturing space. \item This is the first technology for T cell immunotherapies that selectively expands memory T cell populations with greater efficiency relative to - bead-based expansion Others have demonstrated methods that can achieve greater + bead-based expansion. Others have demonstrated methods that can achieve greater expansion of T cells, but not necessarily specific populations that are known to be potent. \item We used \glspl{doe} to discover and validate novel \glspl{cpp}, which is a @@ -1389,9 +1385,9 @@ novel considering the state-of-the-art technology for T cell manufacturing: usage in the development of cell therapies where research often employs a one-factor-at-a-time approach. We believe this method is highly relevant to the development of cell therapies, not only for process optimization but also - hypotheses generation. Furthermore, it is a perfectly natural strategy to use - even at small scale, where the cost of reagents, cells, and materials often - precludes large sample sizes. + hypotheses generation. Furthermore, it is a natural strategy to use even at + small scale, where the cost of reagents, cells, and materials often precludes + large sample sizes. \item The \gls{dms} system is be compatible with static bioreactors such as the G-Rex which has been adopted throughout the cell therapy industry. Thus this technology can be easily incorporated into existing cell therapy process that