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a. Analytical characterization of switch protein production from suitable producer cell line such as K562, including protein production productivity (yields) and protein integrity (mass spec)
b. Assess functional activity of switch produced by LNP-mRNA in vitro using co-culture assays including CLBR001 and antigen-positive target cells mixed with supernatants from producer cell line transfected with LNP-mRNA. Specific reads will be target cell lysis, cytotoxicity, and upregulation of activation markers on C...
(f) Assess pharmacokinetics of LNP-mRNA switch in mouse using IV dosing
a. Conduct pharmacokinetic studies in NSG mice via single and multidose studies and quantitate switch protein in peripheral blood
b. Calculate the amount of time switch concentrations are over EC50 in plasma for each LNP-mRNA generated.
c. Other dosing routes of administration may be compared including intranodal for SWI019 or intratumoral for Her2
(g) Assess in vivo activity in mouse xenograft models (CD19 positive and/or Her2 positive)
a. Test the activity of LNP-mRNA switches in NSG mouse xenograft models in combination with CLBR001 switchable CAR-T cells that assess the following variables:
i. Comparison of multiple LNP-mRNA candidates
ii. Comparison with Fab-based switches
b. Success criteria will include reaching target expected exposures and elimination of tumors in mice.
Lead Optimization & Candidate Selection
(a) Conduct optimization campaign to identify clinically translatable LNP formulation for a single switch target.
a. Optimization will be carried out with CDMO and will include consideration for phospholipids, cholesterol, PEGylated lipids, and cationic or ionizable lipids.
b. Lead opt may also include optimization of 1-methylpseudouridine content of mRNA
(b) Generate optimized LNP-mRNA candidates
a. As described above
(c) Characterize optimized LNP-mRNA candidates at the R&D scale
a. As described above
(d) Assess pharmacokinetics of optimized LNP-mRNA candidates in mouse using IV dosing
a. As described above
b. In addition, analytical assays for detection of mRNA from LNP-mRNA and/or assays for detecting lipid components will be implemented as necessary.
(e) Assess in vivo activity of optimized LNP-mRNA candidates
a. As described above for lead candidates, in addition as described below:
b. Multiple dose levels of LNP-mRNA
c. Dose frequencies of LNP-mRNA ranging from monthly to weekly
d. Tissue PK for mRNA and switch protein will be implemented as appropriate for the target indication.
(f) Rodent tolerability: Multidose rodent tolerability will be carried out in mouse or rat. The expected dosing frequency of these models are expected to be between weekly and monthly
a. Assessment of acute phase reactants (e.g., CRP, IL-6, complement, IP-10) will be monitored
b. Assessment of liver enzyme tests (e.g., ALT, alanine aminotransferase; AST, aspartate aminotransferase; LDH, lactate dehydrogenase)
c. Tissue tropism of the mRNA may be assessed as appropriate using established methods.
(g) Non-human primate (NHP) PK and tolerability
a. Quantitation of switch protein levels in plasma/serum
b. mRNA from the LNP-mRNA will be tested in serum using quantitative RT-PCR
c. ADA for anti-PEG and switch antibodies will be assessed
d. Complement activation factors will be assessed
e. Liver enzymes will be assessed
f. Assessment with and without predosing with steroids may be assessed (if warranted based on rodent studies)
(h) Manufacturing feasibility will include GMP timelines and costs to scale LNP-mRNA to IND
a. A purification method suitable for clinical development will be used for mRNA
b. Analytical criteria specific to mRNA to include the following analytics for candidate selection:
i. Identify (enzymatic degradation)
ii. RNA integrity (capillary electrophoresis)
iii. Residual protein (BCA assay)
iv. Residual DNA (qPCR)
v. Residual dsRNA (dot blot)
vi. % cap (LC-MBS)
vii. Potency (cell-based assay) – optional
(i) DELIVERABLE: A single candidate will be selected that meets prescribed target profile / development criteria.
Timeline: approximately 2 year to development candidate is expected. Due to the exploratory nature of the work, the timeline may be adjusted due to results and there is no guarantee that a successful candidate can be generated for an mRNA switch.
Schedule 2.3.2-b: In-Situ Work Plan
[See attached.]
CONFIDENTIAL 2.3.2-b-1
IN SITU WORK PLAN 2023-2025
This Work Plan summarizes the activities and deliverables to develop an in situ switchable CAR-T platform by Calibr. The in situ platform is expected to be based on an engineered lentiviral vector. Calibr will conduct work to accomplish goals of the program: (a) demonstrate feasibility of in situ approach in the contex...
Work Plan
Period Covered
Deliverable
Background
The development of an in situ-based platform for generation of sCAR-T cells in vivo affords many advantages towards the goal of establishing a universal sCAR-T platform. These are outlined in the slide below presented to AbbVie leadership on Feb 3rd, 2023.
This work plan outlines efforts to create a best-in-class lentiviral vector for in situ delivery of the CAR transgene. The lentiviral platform was selected through a comparison of all available platforms (RNA, retro, transposon, LNP, etc.) based on its low immunogenicity, reduced oncogenic potential (compared with retr...
dosing. The goal of this model is to (a) set a baseline control for engineering efforts; (b) demonstrate feasibility of activating an in situ-generated sCAR-T cell with a separately administered switch; and (c) test the hypothesis that a low systemic dose of lentiviral vector is sufficient to transduce a small number o...
1. Non-engineered lentiviral or retroviral vectors will be dosed IV to transduce T cells in situ in fully immunocompetent mice strain
2. The following parameters will be assessed:
i. Cell tropism/specificity: On-target activity (sCAR-T cell generation), off-target activity (transduction of cells and tissues other than T cells)
ii. In vivo sCAR-T cell expansion and phenotyping
iii. Tolerability (blood chemistry, serum cytokines, weight)
3. Compare with conventional mouse CAR-T cells targeting CD19
a) Engineering of human lentiviral vectors and lead selection:
1. Establish acceptance criteria for lead vector design for in situ application:
i. Criteria will be based on cell tropism/selectivity, tolerability, T cell transduction, and sCAR-T cell expansion and antitumor activity as described in the TPP table
ii. Determine the lowest dose (single dose) that allows for robust sCAR-T expansion through CD19 to later eradicate established solid tumors
2. Design, clone, and generate candidate lentiviral vectors:
i. Determine T cell specificity and ablation of receptors for other cell types
ii. Perform optimization of transduction of T cells in peripheral blood (resting T cells) if necessary
iii. Determine potential for immunogenicity
3. Conduct biology activities to characterize the lentiviral vectors:
i. Perform physical and functional titrations
ii. Perform selectivity assessment in the presence of cell types other than T cells
iii. Assess sensitivity to human complement and T cell transduction in human whole blood
4. Conduct in vivo activities for this program:
i. Profile in vivo vector potency (dose titration), vector biodistribution (if necessary), specificity/cell tropism, and sCART expansion through SWI019 switch
ii. Determine efficacy in humanized mouse models with implanted solid tumors. In these models, human PBMCs will be engrafted on MHC knock-out mice and transduced in vivo with systemically delivered vectors. sCAR-T cells will be expanded with SWI019 and CD19-positive cells and retargeted against a selected solid tumor t...
b) Engineering of packaging cell line to improve the vector attributes.
1. Cell line engineering will attempt to reduce potential for immunogenicity of vectors. Calibr will determine impact of the following approaches:
i. Knock out B2M and Knock in CD47 genes
ii. Clone characterization and selection
iii. Expansion of selected clones
iv. Lentiviral vector generation employing selected clones
2. Conduct biology activities to characterize the lentiviral vectors from (b):
i. Perform physical and functional titrations
ii. Assess immunogenicity of vectors in the presence of myeloid and other immune cells
iii. Assess T cell transduction in human whole blood
3. Conduct in vivo activities in humanized murine models:
i. Profile of vector potency (dose titration), vector biodistribution/selectivity/cell tropism, and sCAR-T cell expansion through SWI019 switch dosing on similar model as above
ii. Efficacy in humanized mouse models with implanted solid tumors. In this step, full reconstitution with a human immune system (including T, B, and myeloid cells) will be required to proof the advantages of the engineering strategies implemented. Therefore, humanized models with CD34+ HSC engrafted instead of PBMCs w...
In situ sCAR-T platform development Discovery Activities
Surrogate model PoC
Engineering and generation of human vectors
In vitro/vivo activities with human vectors