scholarly journals Project Stella: Development and Preclinical Assessment of FOLR1-Directed Chimeric Antigen Receptor T Cells in CBF2AT3-GLIS2/RAM AML

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 2788-2788
Author(s):  
Quy Le ◽  
Sommer Castro ◽  
Thao T. Tang ◽  
Cynthia Nourigat-Mckay ◽  
LaKeisha Perkins ◽  
...  
Keyword(s):  
T Cells ◽  
High Risk ◽  
Cell Line ◽  
Chimeric Antigen Receptor ◽  
Cytolytic Activity ◽  
Target Specificity ◽  
Publicly Traded ◽  
Car T Cells ◽  
Car T

Abstract Background: A rare but highly aggressive type of AML that is only seen in infants with a unique immunophenotype (RAM phenotype) is caused by cryptic CBFA2T3-GLIS2 (CBF/GLIS) fusion. This infant AML is highly refractory to conventional chemotherapy with near uniform fatality despite highly intensive and myeloablative therapy (PMID 23153540). Transcriptome profiling of CBF/GLIS AML has revealed new insights into the pathogenesis of the fusion and uncovered fusion-specific molecular biomarkers that could be used for risk stratification and to inform treatment (PMID 30592296). Studying the largest cohort of these high-risk infants, we demonstrated several alterations in gene expression and transcriptional networks in these CBF/GLIS-positive patient samples that have potential for therapeutic targeting (PMID 31719049). FOLR1, which encodes for folate receptor alpha, was highly and uniquely expressed in CBF/GLIS AML but was entirely absent in AML with other cytogenetics abnormalities and in normal hematopoietic cells. Furthermore, we recently demonstrated that forced expression of CBF/GLIS enhances the proliferation and alters differentiation in cord blood (CB) CD34+ early precursors towards megakaryocytic lineage that recapitulates acute megakaryocytic leukemia seen in infants (PMID 31719049). Of significance, we showed that FOLR1 surface expression is causally linked to CBF/GLIS-induced malignant transformation, thus making it an attractive antigen for targeted therapies against CBF/GLIS AML cells. Given that chimeric antigen receptor (CAR) T cells are extremely effective at eradicating relapsed/refractory B-ALL malignancies, we developed FOLR1-directed CAR T cells for pre-clinical evaluation in CBF/GLIS AML. Methods: We generated a FOLR1-directed CAR using anti-FOLR1 binder (Farletuzumab), IgG4 intermediate spacer and 41-BB/CD3zeta signaling domains. The pre-clinical efficacy of FOLR1 CAR T cells was evaluated against CBF/GLIS AML cell lines in vitro and in vivo. CBF/GLIS AML models include CB CD34+ cells transduced with CBF/GLIS expression construct (CBF/GLIS-CB) and WSU-AML cell line. We also engineered Kasumi-1 cell line to express FOLR1 (Kasumi-1 FOLR1+) to evaluate target specificity (Figure 1A). Results: We tested the target specificity of FOLR1-directed CAR T cells against FOLR1-positive (CBF/GLIS-CB, WSU-AML, Kasumi-1 FOLR1+) and FOLR1-negative (Kasumi-1) cells. CD8 FOLR1 CAR T cells demonstrated cytolytic activity against FOLR1 positive but not FOLR1 negative cells (Figure 1B). Furthermore, both CD8 and CD4 FOLR1 CAR T cells produced higher levels of IL-2, IFN-γ, and TNF-α and proliferated more robustly than did unmodified T cells when co-incubated with FOLR1 positive but not FOLR1 negative cells (Figure 1C). These results indicate highly specific reactivity of FOLR1 CAR T cells against AML cells expressing FOLR1. We next investigated the in vivo efficacy of FOLR1-directed CAR T cells. In CBF/GLIS-CB, WSU-AML, and Kasumi-1 FOLR1+ xenograft models, treatment with FOLR1 CAR T cells induced leukemia clearance, while disease progression occurred in all mice that received unmodified T cells (Figure 1D). Activity of FOLR1 CAR T cells in vivo was target specific, as they did not limit the leukemia progression nor extend the survival of Kasumi-1 xenografts (Figure 1D). To determine whether FOLR1 is expressed on normal HSPCs, we characterized FOLR1 expression in normal CB CD34+ samples. FOLR1 expression was entirely silent in HSPC subsets (Figure 1E). Consistent with lack of expression, no cytolytic activity was detected against HPSCs Moreover, FOLR1 CAR T cells did not affect the self-renewal and multilineage differentiation capacity of normal HSPCs as compared to unmodified control T cells (Figure 1F), whereas significant eradication of colonies were detected in the CBF/GLIS-CB cells (Figure 1G). Conclusion: In this study, we demonstrate that FOLR1 CAR T effectively eradicates CBF/GLIS AML cells without compromising normal HSPCs, providing a promising approach for the treatment of high-risk CBF/GLIS AML. Transition of this CAR T to clinical development for infant AML is underway. Figure 1 Figure 1. Disclosures Hylkema: Moderna: Current equity holder in publicly-traded company; Quest Diagnostics Inc: Current equity holder in publicly-traded company. Pardo: Hematologics, Inc.: Current Employment. Eidenschink Brodersen: Hematologics, Inc.: Current Employment, Other: Equity Ownership. Loken: Hematologics, Inc.: Current Employment, Other: current equity holder in a privately owned company.

scholarly journals Tri-Specific CD19xCD20xCD22 VHH CAR-T Cells (LCAR-AIO) Eradicate Antigen-Heterogeneous B Cell Tumors, Enhance Expansion, and Prolong Persistence in Preclinical In Vivo Models

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 1700-1700
Author(s):  
Zhe (joy) Zhou ◽  
Yue Han ◽  
Hong-Bo Pan ◽  
Cai-Jun Sang ◽  
Dong-Lin Shi ◽  
...  
Keyword(s):  
T Cells ◽  
B Cell ◽  
Treatment Efficacy ◽  
Cytolytic Activity ◽  
Publicly Traded ◽  
Car T Cells ◽  
Car T ◽  
Ifn Γ

Abstract Introduction: Anti-CD19 CAR-T therapy has achieved remarkable treatment efficacy in B cell lymphoma. However, targeting CD19 antigen alone can only benefit about half of patients with B cell malignancies. The FDA-approved CD19 CAR-T therapies all use same binder, which is murine FMC63 scFv targeting CD19 and up to 39%-88% of patients have relapsed. Possible mechanisms of relapse include mutations or downregulation of the targeted antigen, CD19, however, the targetable expression of CD20 and CD22 is preserved. In addition, immunogenicity against murine FMC63 scFv could have a negative impact on possible re-dosing regimen. To overcome these limitations, we designed and developed a novel tri-specific VHH CAR-T, targeting three antigens that include CD19, CD20 and CD22, for treating patients who relapsed from prior CAR-T therapies. Methods: We engineered mono-, bi-, or tri-specific VHH CAR constructs targeting CD19, CD20 and/or CD22 respectively in a lentiviral vector. The mono-, bi- or tri-specific CAR-T cells were tested against tumor lines expressing single, dual or triple antigens in an in vitro cytotoxicity assay. In addition, we evaluated the contribution of different CAR backbones, and possible combinations of scFv, VH or VHH to CAR design. We hypothesized that our lead tri-specific VHH CAR-T, LCAR-AIO, would potently inhibit tumors with heterogeneous Ag expression and prevent Ag escape. To validate this, we compared in vitro cytolytic activity and cytokine production of LCAR-AIO CAR-T to anti-CD19 FMC63 CAR-T against CD19 +CD20 +CD22 + Raji.Luc and CD19KOCD20 +CD22 +Raji.Luc cells . In vivo treatment efficacy and CAR-T persistence were also investigated in NCG murine model xenografted with Raji tumor line. 0.3x10 6 CAR +T cells or dose-matched untransduced T cells were given to NCG mice four days post i.v. implantation of Raji.Luc tumor cells. Tumor growth was monitored weekly by bioluminescence imaging until achieved endpoint (55 days), and CAR-T persistence was determined using genomic DNA level. Results: Tri-specific VHH CAR-T cells can mediate dose-dependent cytotoxicity against Raji tumor lines. Compared to mono- or bi-specific VHH or scFv CAR-T, tri-specific VHH CAR-T demonstrated equal or better cytolytic activity. Our lead tri-VHH CAR-T, LCAR-AIO, was able to specifically lyse K652 over-expressing single target such as CD19, CD20 or CD22, at the similar level to mono-specific CD19, CD20 or CD22 VHH CAR-T. Since no blocking effect of recognition against these three antigens was observed, our result suggested that all three VHHs in LCAR-AIO are functional. In comparison to anti-CD19 FMC63 scFv CAR-T, LCAR-AIO exhibited higher lytic activity and IFN-γ production against Raji.Luc tumor lines in vitro. In addition, LCAR-AIO retained its robust lytic activity and IFN-γ production when co-cultured with CD19KO-Raji.Luc cells while anti-CD19 FMC63 scFv CAR-T could not, suggesting LCAR-AIO may prevent tumor escape due to loss of CD19. Furthermore, comparison of LCAR-AIO to mono-scFv CAR-T (anti-CD19 FMC63-BBz, anti-CD20 Leu16-BBz or anti-CD22 m971-BBz) was performed in NCG mice xenografted with Raji cell line, LCAR-AIO exhibited better T cell expansion, longer persistence, and superior efficacy in eliminating tumors. Conclusions: Based on in vitro and in vivo preclinical data, tri-specific CD19xCD20xCD22 VHH CAR-T can be effective targeting tumors lack of CD19 expression, therefore, it has the potential of treating relapsed patients with prior CD19 CAR-T therapy. The feasibility of making tri-specific CAR-T would help to extend this technology to solid cancers where heterogeneity poses a major challenge at current stage. Figure 1 Figure 1. Disclosures Zhou: Legend Biotech: Current Employment, Current equity holder in publicly-traded company. Han: Legend Biotech: Current Employment, Current equity holder in publicly-traded company. Pan: Legend Biotech: Current Employment, Current equity holder in publicly-traded company. Sang: Legend Biotech: Current Employment, Current equity holder in publicly-traded company. Shi: Legend Biotech: Current Employment. Feng: Legend Biotech: Current Employment. Xiao: Legend Biotech: Current Employment. Zhuang: Legend Biotech: Current Employment, Current equity holder in publicly-traded company. Wang: Legend Biotech: Current Employment, Current equity holder in publicly-traded company. Fan: Legend Biotech: Current Employment, Current equity holder in publicly-traded company.

scholarly journals Targeting PRAME with TCR-Mimic CAR T Cells in AML

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 733-733
Author(s):  
Anisha M Loeb ◽  
Sommer Castro ◽  
Cynthia Nourigat-Mckay ◽  
LaKeisha Perkins ◽  
Laura Pardo ◽  
...  
Keyword(s):  
T Cells ◽  
Cytolytic Activity ◽  
Publicly Traded ◽  
Car T Cells ◽  
Novel Approach ◽  
Car T ◽  
Xenograft Mice ◽  
Ifn Γ ◽  
Specific Reactivity

Abstract Chimeric antigen receptor (CAR) Ts have been effective in pre-B ALL, but their efficacy in AML has yet to be established. A significant barrier to effective CAR T therapy for AML is the substantial overlap of cell surface antigens expressed on AML and normal hematopoietic cells. To overcome this barrier, we profiled the transcriptome of over 3000 AML cases in children and young adults and contrasted this to normal hematopoietic tissues in search for AML-restricted targets (high expression in AML, silence in normal hematopoiesis). This led to the discovery of over 200 AML-restricted genes. Of these, Preferentially Expressed Antigen in Melanoma (PRAME) is among one of the highest expressing AML-restricted genes (Figure 1A) and, given its previous track record as a target for a variety of cancers, we selected this target for further assessment and therapeutic development in AML. However, PRAME is intracellular and therefore is inaccessible for targeting with conventional CAR T. Recently, a novel approach to target intracellular antigens was developed using TCR mimic (mTCR) antibodies, which recognize peptide/human leukocyte antigen (HLA) complexes on the tumor cell surface in a similar mode of recognition as authentic T Cell Receptors (TCRs). The Pr20 antibody was developed to recognize the PRAME ALY peptide in the context of HLA-A*02. Utilizing this Pr20 antibody, we developed a mTCR CAR T targeting PRAME and evaluated its preclinical efficacy in AML. The VL and VH sequences from Pr20 were used to construct the single-chain fragment variable domain of the 41-BB/CD3ζ CAR vector. We evaluated PRAME mTCR CAR T cells against OCI-AML-2 and THP-1 AML cell lines (PRAME +/HLA-A*02 +), K562 CML cell line (PRAME +/HLA-A*02 -) and HEK293T (293T) (PRAME -/HLA-A*02 +). Using a PE-conjugated Pr20 antibody, we confirmed that OCI-AML2 and THP-1 express PRAME ALY: HLA-A*02 but not K562 and 293T by flow cytometry (Figure 1B). As further confirmation, AML blasts in primary patient samples also stained with the Pr20 antibody (Figure 1C). For in-vivo studies, leukemia-bearing mice were treated with unmodified T or PRAME mTCR CAR T cells at 5x10 6 cells (1:1 CD4:CD8) per mouse 1 week following leukemia injection. Leukemia burden was measured weekly by bioluminescence IVIS imaging. Cells were treated with 10ng/mL of IFN-γ prior to co-incubation with T cells for 16 hours. PRAME mTCR CAR T cells demonstrated potent cytolytic activity against OCI-AML2 and THP1 but not against K562 or 293T cells, following co-incubation with target cells for 24 hours (Figure 1D). Consistent with potent, target-specific reactivity against PRAME ALY: HLA-A*02 positive cells, increased levels of IFN-γ, IL-2 and TNF-α were detected in cocultures of CAR T cells with OCI-AML2 and THP1 but not with K562 and 293T cells (Figure 1D). The cytolytic activity of PRAME mTCR CAR T cells extended to primary AML specimens expressing the PRAME ALY: HLA-A*02 antigen (data not shown). In-vivo efficacy of PRAME mTCR CAR T was demonstrated in OCI-AML2 and THP-1 CDX models (Figure 1E). Treatment with CAR T cells induced leukemia clearance and significantly reduced leukemia burden in OCI-AML2 and THP-1 xenograft mice, respectively, while treatment with unmodified T cells exhibited leukemia progression (Figure 1E). The anti-leukemia activity of CAR T cells resulted in enhanced survival in OCI-AML2 (p=0.0035) and THP-1 (p=0.0047) xenografts (Figure 1F). The in-vivo activity of PRAME mTCR CAR T cells was target specific, as treatment with CAR T cells did not affect leukemia burden and survival in K562 xenograft mice (Figure 1F). Given that IFN-γ promotes PRAME presentation, we investigated whether treatment of IFN-γ would enhance cytolytic activity of PRAME mTCR CAR T cells. OCI-AML2 and THP-1 cells pretreated with IFN-γ were more sensitive to cytolysis compared to untreated controls (Figure 1G). In this study, we demonstrate the therapeutic potential of targeting PRAME with mTCR CAR T cells in AML. We show potent, target-specific reactivity of PRAME mTCR CAR T cells against PRAME ALY: HLA-A*02 positive AML cells, both in-vitro and in-vivo. We further demonstrate that the activity of PRAME mTCR CAR T cells can be enhanced with IFN-γ treatment, providing a useful strategy to increase efficacy. Thus, the results presented provide a novel approach to target PRAME with CAR T cells and compelling data to evaluate PRAME mTCR CAR T cells in AML clinical trials. Figure 1 Figure 1. Disclosures Pardo: Hematologics, Inc.: Current Employment. Hylkema: Quest Diagnostics Inc: Current equity holder in publicly-traded company; Moderna: Current equity holder in publicly-traded company. Scheinberg: Eureka Therapeutics: Current equity holder in publicly-traded company.

112 Rational design of chimeric antigen receptor T cells against glypican 3 decouples toxicity from therapeutic efficacy

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A124-A124
Author(s):  
Letizia Giardino ◽  
Ryan Gilbreth ◽  
Cui Chen ◽  
Erin Sult ◽  
Noel Monks ◽  
...  
Keyword(s):  
T Cells ◽  
Chimeric Antigen Receptor ◽  
Antigen Receptor ◽  
Single Chain ◽  
High Affinity ◽  
Car T Cells ◽  
Car T ◽  
Animal Care ◽  
Cytotoxic Function

BackgroundChimeric antigen receptor (CAR)-T therapy has yielded impressive clinical results in hematological malignancies and it is a promising approach for solid tumor treatment. However, toxicity, including on-target off-tumor antigen binding, is a concern hampering its broader use.MethodsIn selecting a lead CAR-T candidate against the oncofetal antigen glypican 3 (GPC3), we compared CAR bearing a low and high affinity single-chain variable fragment (scFv,) binding to the same epitope and cross-reactive with murine GPC3. We characterized low and high affinity CAR-T cells immunophenotype and effector function in vitro, followed by in vivo efficacy and safety studies in hepatocellular carcinoma (HCC) xenograft models.ResultsCompared to the high-affinity construct, the low-affinity CAR maintained cytotoxic function but did not show in vivo toxicity. High-affinity CAR-induced toxicity was caused by on-target off-tumor binding, based on the evidence that high-affinity but not low-affinity CAR, were toxic in non-tumor bearing mice and accumulated in organs with low expression of GPC3. To add another layer of safety, we developed a mean to target and eliminate CAR-T cells using anti-TNFα antibody therapy post-CAR-T infusion. This antibody functioned by eliminating early antigen-activated CAR-T cells, but not all CAR-T cells, allowing a margin where the toxic response could be effectively decoupled from anti-tumor efficacy.ConclusionsSelecting a domain with higher off-rate improved the quality of the CAR-T cells by maintaining cytotoxic function while reducing cytokine production and activation upon antigen engagement. By exploring additional traits of the CAR-T cells post-activation, we further identified a mechanism whereby we could use approved therapeutics and apply them as an exogenous kill switch that would eliminate early activated CAR-T following antigen engagement in vivo. By combining the reduced affinity CAR with this exogenous control mechanism, we provide evidence that we can modulate and control CAR-mediated toxicity.Ethics ApprovalAll animal experiments were conducted in a facility accredited by the Association for Assessment of Laboratory Animal Care (AALAC) under Institutional Animal Care and Use Committee (IACUC) guidelines and appropriate animal research approval.

Combinatorial Antigen Targeting Strategy for Acute Myeloid Leukemia

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 22-23
Author(s):  
Pinar Ataca Atilla ◽  
Mary K McKenna ◽  
Norihiro Watanabe ◽  
Maksim Mamonkin ◽  
Malcolm K. Brenner ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Board Of Directors ◽  
Tumor Control ◽  
Publicly Traded ◽  
Advisory Committees ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T

Introduction: Efforts to safely and effectively treat acute myeloid leukemia (AML) by targeting a single leukemia associated antigen with chimeric antigen receptor T (CAR T) cells have had limited success. We determined whether combinatorial expression of chimeric antigen receptors directed to two different AML associated antigens would augment tumor eradication and prevent relapse in targets with heterogeneous expression of myeloid antigens. Methods: We generated CD123 and CD33 targeting CARs; each containing a 4-1BBz or CD28z endodomain. We analyzed the anti-tumor activity of T cells expressing each CAR alone or in co-transduction with a CLL-1 CAR with CD28z endodomain and CD8 hinge previously optimized for use in our open CAR-T cell trial for AML (NCT04219163). We analyzed CAR-T cell phenotype, expansion and transduction efficacy by flow cytometry and assessed function by in vitro and in vivo activity against AML cell lines expressing high, intermediate or low levels of the target antigens (Molm 13= CD123 high, CD33 high, CLL-1 intermediate, KG1a= CD123 low, CD33 low, CLL-1 low and HL60= CD123 low, CD33 intermediate, CLL-1 intermediate/high) For in vivo studies we used NOD.SCID IL-2Rg-/-3/GM/SF (NSGS) mice with established leukemia, determining antitumor activity by bioluminescence imaging. Results: We obtained high levels of gene transfer and expression with both single (CD33.4-1BBʓ, CD123.4-1BBʓ, CD33.CD28ʓ, CD123.CD28ʓ, CLL-1 CAR) and double transduction CD33/CD123.4-1BBʓ or CD33/CD123.CD28ʓ) although single-transductants had marginally higher total CAR expression of 70%-80% versus 60-70% after co-transduction. Constructs containing CD28 co-stimulatory domain exhibited rapid expansion with elevated peak levels compared to 41BB co-stim domain irrespective of the CAR specificity. (p<0.001) (Fig 1a). In 72h co-culture assays, we found consistently improved anti-tumor activity by CAR Ts expressing CLL-1 in combination either with CD33 or with CD123 compared to T cells expressing CLL-1 CAR alone. The benefit of dual expression was most evident when the target cell line expressed low levels of one or both target antigens (e.g. KG1a) (Fig 1b) (P<0.001). No antigen escape was detected in residual tumor. Mechanistically, dual expression was associated with higher pCD3ʓ levels compared to single CAR T cells on exposure to any given tumor (Fig 1c). Increased pCD3ʓ levels were in turn associated with augmented CAR-T degranulation (assessed by CD107a expression) in both CD4 and CD8 T cell populations and with increased TNFα and IFNɣ production (p<0.001 Fig 1d). In vivo, combinatorial targeting with CD123/CD33.CD28ʓ and CLL-1 CAR T cells improved tumor control and animal survival in lines (KG1a, MOLM13 and HL60) expressing diverse levels of the target antigens (Fig 2). Conclusion: Combinatorial targeting of T cells with CD33 or CD123.CD28z CARs and CLL-1-CAR improves CAR T cell activation associated with superior recruitment/phosphorylation of CD3ʓ, producing enhanced effector function and tumor control. The events that lead to increased pCD3ʓ after antigen engagement in the dual transduced cells may in part be due to an overall increase in CAR expression but may also reflect superior CAR recruitment after antigen engagement. We are now comparing the formation, structure, and stability of immune synapses in single and dual targeting CARs for AML. Disclosures Brenner: Walking Fish: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Bluebird Bio: Membership on an entity's Board of Directors or advisory committees; Tumstone: Membership on an entity's Board of Directors or advisory committees; Tessa Therapeutics: Membership on an entity's Board of Directors or advisory committees, Other: Founder; Maker Therapeutics: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees, Other: Founder; Memmgen: Membership on an entity's Board of Directors or advisory committees; Allogene: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees. Atilla:Bluebird Bio: Membership on an entity's Board of Directors or advisory committees; Tumstone: Membership on an entity's Board of Directors or advisory committees; Tessa Therapeutics: Membership on an entity's Board of Directors or advisory committees, Other: founder; Marker Therapeuticsa: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees, Other: Founder, Patents & Royalties; Allogene: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Walking Fish: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties; Memgen: Membership on an entity's Board of Directors or advisory committees; KUUR: Membership on an entity's Board of Directors or advisory committees.

scholarly journals Chimeric Antigen Receptor T Cells Specific for CLL-1 for Treatment of Acute Myeloid Leukemia

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 2205-2205 ◽  
Author(s):  
Elisa De Togni ◽  
Miriam Y Kim ◽  
Matt L Cooper ◽  
Julie Ritchey ◽  
Julie O'Neal ◽  
...  
Keyword(s):  
T Cells ◽  
Cell Line ◽  
Myeloid Leukemia ◽  
Cytotoxic Effects ◽  
Car T Cells ◽  
Human T Cells ◽  
Car T ◽  
Acute Myeloid

Abstract Chimeric antigen receptor (CAR) T cells are a novel therapeutic approach which have shown good clinical outcomes in patients receiving CD19 CAR T cells for B cell acute lymphoblastic leukemia. CAR T cells are made to express a CAR that recognizes a specific surface antigen on a cell upon which they can then exert cytotoxic effects. We aim to extend the success of this therapy to acute myeloid leukemia (AML), a disease with generally poor clinical outcomes. However, due to the genetic heterogeneity characteristic of AML and the limited number of distinctive tumor markers, it has been difficult to find effective targets for CAR T cells on AML. C-type lectin like molecule-1 (CLL-1), also known as CD371, is a transmembrane glycoprotein that is expressed on about 90% of AML patient samples. CLL-1 may function as an inhibitory signaling receptor, as it contains an intracellular immunoreceptor tyrosine based inhibitory motif (ITIM). CLL-1 is primarily expressed on myeloid lineage cells in the bone marrow and in peripheral blood. While CLL-1 has been shown to be expressed on some granulocytes in the spleen, it is not reported to be expressed in non-hematopoietic tissues or on hematopoietic stem cells, which make CLL-1 a potential therapeutic target for AML. We generated two types of CLL-1 CARs, termed A and B, by using two different single chain variable fragments (scFvs) recognizing CLL-1. We used second generation CARs containing the scFvs, CD8 hinge and transmembrane domain, 4-1BB co-stimulatory domain, and CD3 zeta signaling domains. Using a lentiviral vector, we transferred the CAR gene into healthy donor human T cells and detected CAR expression by flow cytometry. We then tested the specific cytotoxic effects of CLL-1 CART-A and B on a CLL-1-expressing AML cell line, U937, by conducting a 4-hour chromium release assay. We found that both CAR T cells exhibited a dose-dependent killing of U937 (CLL-1 positive), while the untransduced (UTD) T cells had no cytotoxic effect (Figure 1A). We also found that U937 induces degranulation of CLL-1 CAR T cells as measured by CD107a expression by flow cytometry, while Ramos, a CLL-1 negative cell line, does not (Figure 1B). We then proceeded to investigate the in vivo efficacy of the CAR T cells. We injected NOD/SCID/IL2RG-null (NSG) mice with 1 x 106 THP-1 cells, a CLL-1 positive cell line. We confirmed engraftment by bioluminescent imaging (BLI) after 7 days and then injected 4 x 106 UTD, CLL-1 CART-A or CLL-1 CART-B. Surprisingly, only one of the CAR constructs, CLL-1 CART-A, showed significant activity in vivo, although both CARs had shown comparable activity in vitro. CLL-1 CART-A treated mice had delayed tumor progression and significantly increased length of survival (85 days vs. 63 days, p = 0.0021) compared to mice injected with UTD (Figure 1C and D). While CLL-1 CART-B treated mice also exhibited slower tumor growth and a trend towards better survival (72 days vs. 63 days, p=0.0547) this was not statistically significant. Post-mortem analysis showed that human T cells that continued to express CAR were present in the tumor, bone marrow and spleen of mice treated with CLL-1 CART-A only, while the UTD and CLL-1 CART-B treated mice showed tumor in all organs and no T cells. In summary, we show that CLL-1 CAR T cells can selectively eliminate CLL-1 positive target cells in vitro and in vivo, albeit with different degrees of efficacy modulated by the scFv. Studies are ongoing to investigate the mechanism behind the differential activity of these CAR constructs and to increase the long-term antitumor efficacy. Our results demonstrate that targeting CLL-1 using CAR T cell therapy holds promise for the treatment of AML. Disclosures Cooper: WUGEN: Consultancy, Equity Ownership.

CD19-Redirected Chimeric Antigen Receptor T (CART19) Cells Induce a Cytokine Release Syndrome (CRS) and Induction of Treatable Macrophage Activation Syndrome (MAS) That Can Be Managed by the IL-6 Antagonist Tocilizumab (toc).

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2604-2604 ◽  
Author(s):  
Stephan A. Grupp ◽  
David L Porter ◽  
David T Teachey ◽  
David M. Barrett ◽  
Anne Chew ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Chimeric Antigen Receptor ◽  
Tumor Lysis Syndrome ◽  
Antigen Receptor ◽  
Car T Cells ◽  
Car T ◽  
Anti Tumor Activity

Abstract Abstract 2604 We previously reported on CART19 cells expressing a chimeric antigen receptor (CAR) with intracellular activation and costimulatory domains. Infusion of these cells results in 100 to 100,000× in vivo proliferation, tumor lysis syndrome followed by durable antitumor activity, and prolonged persistence in pts with B cell tumors. Here we report that in vivo proliferation of CART19 cells and potent anti-tumor activity is associated with CRS, leading to hemophagocytic lymphohistiocytosis (HLH), also termed MAS. We propose that MAS/HLH is a unique biomarker that is associated with and may be required for potent anti-tumor activity. Autologous T cells were lentivirally transduced with a CAR composed of anti-CD19 scFv/4-1BB/CD3-zeta, activated/expanded ex-vivo with anti-CD3/anti-CD28 beads, and then infused into ALL or CLL pts with persistent disease after 2–8 prior treatments. CART19 anti ALL activity was also modeled in a xenograft mouse model with high level of human ALL/human T cell engraftment and simultaneous detection of CAR T cells and ALL using 2-color bioluminescent imaging. We describe updated results of 10 pts who received CART19 cells elsewhere at ASH (Porter, et al), including 9 pts with CLL and 1 pediatric pt with relapsed refractory ALL. 6/9 evaluable pts had a CR or PR, including 4 sustained CRs. While there was no acute infusional toxicity, all responding pts also developed CRS. All had high fevers, as well as grade 3 or 4 hypotension/hypoxia. CRS preceded peak blood expression of CART19 cells, and then increased in intensity until the CART19 cell peak (D10–31 after infusion). The ALL pt experienced the most significant toxicity, with grade 4 hypotension and respiratory failure. Steroid therapy on D6 resulted in no improvement. On D9, noting high levels of TNFa and IL-6 (peak increases above baseline: IFNg at 6040x; IL-6 at 988x; IL-2R at 56x, IL-2 at 163× and TNFa at 17x), we administered TNFa and IL-6 antagonists entanercept and toc. This resulted in resolution of fever and hypotension within 12hr and a rapid wean from ventilator support to room air. These interventions had no apparent impact on CART19 cell expansion or efficacy: peak of CAR T cells (2539 CAR+ cells/uL; 77% of CD3 cells by flow) occurred on D11, and D23 bone marrow showed CR with negative MRD, compared to her initial on-study marrow which showed 65% blasts. Although she had no history of CNS ALL, spinal fluid showed detectable CART19 cells (21 lymphs/mcL; 78% CAR+). At 4mo post infusion, this pt remains in CR, with 17 CART19 cells/uL in the blood and 31% CAR+ CD3 cells in the marrow. Clinical assessment of subsequent responding patients shows all had evidence of MAS/HLH including dramatic elevations of ferritin and histologic evidence of HLH. Peak ferritin levels range from 44,000 to 605,000, preceding and continuing with peak T cell proliferation. Other consistent findings include rapid onset hepatosplenomegaly unrelated to disease and moderate DIC. Subsequently, 3 CLL patients have also been treated with toc, also with prompt and striking resolution of high fevers, hypotension and hypoxia. 1 received toc on D10 and achieved a CR accompanied by CART19 expansion. 1 had rapid resolution of CRS following toc administration on day 9 and follow up for response is too short. A 3rd CLL pt received toc on D3 for early fevers and had no CART-19 proliferation and no response. To model the timing of cytokine blockade, xenografts using bioluminescent primary pediatric ALL were established and then treated with extra cells from the clinical manufacture. The CART19 cells proliferated and resulted in prolonged survival. Cytokine blockade prior to T cell infusion with toc and/or etanercept abrogated disease control with less in vivo proliferation of infused CART19 cells, confirming the result seen in the one pt given early toc (D3). The optimal time and threshold to trigger cytokine blockade is currently being tested in these models. CART19 T cells can produce massive in-vivo expansion, long-term persistence, and anti-tumor efficacy, but can also induce significant CRS with features suggestive of MAS/HLH that responds rapidly to cytokine blockade. Given prior to initiation of significant CART19 proliferation, blockade of TNFa and/or IL-6 may interfere with proliferation and effector function, but if given at a point where cell proliferation is underway, toc may ameliorate the symptoms that we have observed correlate with robust clinical responses. Disclosures: Off Label Use: tocilizumab for cell therapy toxicity. Levine:University of Pennsylvania: financial interest due to intellectual property and patents in the field of cell and gene therapy. Conflict of interest is managed in accordance with University of Pennsylvania policy and oversight Patents & Royalties; TxCell: Consultancy, Membership on an entity's Board of Directors or advisory committees. Kalos:University of Pennsylvania: Patents & Royalties. June:Novartis: Research Funding, institution owned patents have been licensed by Novartis, institution owned patents have been licensed by Novartis Patents & Royalties.

Opposing Effects of PD-1/PD-L1/L2 Engagement and IFN-γ/TNF-α in the Treatment of AML w/ Anti-CD33 Chimeric Antigen Receptor-Modified T Cells

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 5891-5891
Author(s):  
Jacob Halum Basham ◽  
Terrence L. Geiger
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Lymphocytes ◽  
Chimeric Antigen Receptor ◽  
Short Term ◽  
Car T Cells ◽  
Tnf Α ◽  
Car T ◽  
Ifn Γ

Abstract Chimeric antigen receptor-modified T lymphocytes (CART cells) have shown benefit as an adjuvant immunotherapy in the treatment of B cell malignancies. This success of re-targeted T cells has not been extended to other hematologic malignancies. We have developed an immunotherapeutic approach to treat acute myeloid leukemia (AML) using CAR T cells re-directed against the myeloid-specific antigen CD33 (CART-33). CART-33 cells are potent and specific in eliminating AML cells in vitro and in vivo. Despite this, CART-33 cells have shown poor in vivo expansion and persistence in NOD-SCID IL2rγ (-/-) (NSG) AML xenograft models. To address the reason for this, we assessed the impact of AML-expressed programmed death ligands 1 & 2 (PD-L1/2) on CART-33 cell activity. PD-L1 inhibits T cell functions upon binding PD-1, which is upregulated with T cell activation. Less is known about PD-L2's effect. Interferon-gamma (IFN-γ), a primary effector cytokine secreted by CD4+ and CD8+ effector T cells, is a known potent inducer of PD-L1 on AML blasts. Using AML cell lines U937, Oci-AML3, CMK, and MV4-11 we show that IFN-γ, TNF-α, and activated CART-33 supernatant can induce up-regulation of PD-L1 and PD-L2 on AML. IFN-γ and TNF-α synergize strongly in up-regulating PD-1 ligands on AML. The kinetics and induction of PD-L2 are distinct from that of PD-L1. Although PD-L1 is well documented to suppress T cell function via ligation of T cell expressed PD-1, induction of PD-L1/L2 had no effect on the cytolytic activity of CART-33 cells against AML in short term (<48 h) cultures. Paradoxically, 24 hr pre-treatment of AML with either IFN-γ or CART-33 supernatant increased AML susceptibility to killing by CART-33 cells despite elevated expression of PD-L1/L2 by AML. Our results highlight the regulatory complexity of AML cytolysis by re-targeted T lymphocytes, and argue that tumor-expressed PD-L1 and PD-L2 impacts the sustainability, but not short-term killing activity, of adoptively transferred CAR T cells in the treatment of AML. Disclosures No relevant conflicts of interest to declare.

scholarly journals CRISPR-mediated insertion of a chimeric antigen receptor produces nonviral T cell products capable of inducing solid tumor regression

2021 ◽  
Author(s):  
Katherine Mueller ◽  
Nicole Piscopo ◽  
Matthew Forsberg ◽  
Louise Saraspe ◽  
Amritava Das ◽  
...  
Keyword(s):  
T Cells ◽  
Chimeric Antigen Receptor ◽  
Viral Vectors ◽  
Viral Vector ◽  
Tumor Regression ◽  
Antigen Receptor ◽  
Car T Cells ◽  
Car T

Chimeric antigen receptor (CAR) T cells traditionally harbor viral vectors that encode the CAR transgene in the genome. However, viral vector manufacturing typically is resource intensive, suffers from batch-to-batch variability, and includes several animal components, adding regulatory and supply chain pressures. Here, CAR T cells were generated within nine days using recombinant SpCas9 protein and nucleic acids, without any viral vectors or animal components. In comparison to traditional retroviral CAR T cells, nonviral CRISPR CAR T cells exhibit TRAC-targeted genomic integration of the CAR transgene, higher frequency of gene expression signatures associated with a memory phenotype, low receptor signaling prior to infusion, and potent cytotoxicity against GD2+ neuroblastoma in vitro and in vivo. This proof-of-principle study eliminating viral vectors and animal components during CAR gene transfer could enable more flexible and scalable manufacturing of clinically-relevant, high-quality CAR T cells to treat cancers, including solid tumors.

scholarly journals The roles of T cell competition and stochastic extinction events in chimeric antigen receptor T cell therapy

2021 ◽  
Vol 288 (1947) ◽  
Author(s):  
Gregory J. Kimmel ◽  
Frederick L. Locke ◽  
Philipp M. Altrock
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Therapy ◽  
Chimeric Antigen Receptor ◽  
Antigen Receptor ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T

Chimeric antigen receptor (CAR) T cell therapy is a remarkably effective immunotherapy that relies on in vivo expansion of engineered CAR T cells, after lymphodepletion (LD) by chemotherapy. The quantitative laws underlying this expansion and subsequent tumour eradication remain unknown. We develop a mathematical model of T cell–tumour cell interactions and demonstrate that expansion can be explained by immune reconstitution dynamics after LD and competition among T cells. CAR T cells rapidly grow and engage tumour cells but experience an emerging growth rate disadvantage compared to normal T cells. Since tumour eradication is deterministically unstable in our model, we define cure as a stochastic event, which, even when likely, can occur at variable times. However, we show that variability in timing is largely determined by patient variability. While cure events impacted by these fluctuations occur early and are narrowly distributed, progression events occur late and are more widely distributed in time. We parameterized our model using population-level CAR T cell and tumour data over time and compare our predictions with progression-free survival rates. We find that therapy could be improved by optimizing the tumour-killing rate and the CAR T cells' ability to adapt, as quantified by their carrying capacity. Our tumour extinction model can be leveraged to examine why therapy works in some patients but not others, and to better understand the interplay of deterministic and stochastic effects on outcomes. For example, our model implies that LD before a second CAR T injection is necessary.

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