98 ATA3271: an armored, next-generation off-the-shelf, allogeneic, mesothelin-CAR T cell therapy for solid tumors

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A109-A109
Author(s):  
Jiangyue Liu ◽  
Xianhui Chen ◽  
Jason Karlen ◽  
Alfonso Brito ◽  
Tiffany Jheng ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Next Generation ◽  
Phase 3 ◽  
T Cell Therapy ◽  
Cell Therapies ◽  
Car T Cells ◽  
Car T

BackgroundMesothelin (MSLN) is a glycosylphosphatidylinositol (GPI)-anchored membrane protein with high expression levels in an array of malignancies including mesothelioma, ovaria, non-small cell lung cancer, and pancreatic cancers and is an attractive target antigen for immune-based therapies. Early clinical evaluation of autologous MSLN-targeted chimeric antigen receptor (CAR)-T cell therapies for malignant pleural mesothelioma has shown promising acceptable safety1 and have recently evolved with incorporation of next-generation CAR co-stimulatory domains and armoring with intrinsic checkpoint inhibition via expression of a PD-1 dominant negative receptor (PD1DNR).2 Despite the promise that MSLN CAR-T therapies hold, manufacturing and commercial challenges using an autologous approach may prove difficult for widespread application. EBV T cells represent a unique, non-gene edited approach toward an off-the-shelf, allogeneic T cell platform. EBV-specific T cells are currently being evaluated in phase 3 trials [NCT03394365] and, to-date, have demonstrated a favorable safety profile including limited risks for GvHD and cytokine release syndrome.3 4 Clinical proof-of-principle studies for CAR transduced allogeneic EBV T cell therapies have also been associated with acceptable safety and durable response in association with CD19 targeting.5 Here we describe the first preclinical evaluation of ATA3271, a next-generation allogeneic CAR EBV T cell therapy targeting MSLN and incorporating PD1DNR, designed for the treatment of solid tumor indications.MethodsWe generated allogeneic MSLN CAR+ EBV T cells (ATA3271) using retroviral transduction of EBV T cells. ATA3271 includes a novel 1XX CAR signaling domain, previously associated with improved signaling and decreased CAR-mediated exhaustion. It is also armored with PD1DNR to provide intrinsic checkpoint blockade and is designed to retain functional persistence.ResultsIn this study, we characterized ATA3271 both in vitro and in vivo. ATA3271 show stable and proportional CAR and PD1DNR expression. Functional studies show potent antitumor activity of ATA3271 against MSLN-expressing cell lines, including PD-L1-high expressors. In an orthotopic mouse model of pleural mesothelioma, ATA3271 demonstrates potent antitumor activity and significant survival benefit (100% survival exceeding 50 days vs. 25 day median for control), without evident toxicities. ATA3271 maintains persistence and retains central memory phenotype in vivo through end-of-study. Additionally, ATA3271 retains endogenous EBV TCR function and reduced allotoxicity in the context of HLA mismatched targets. ConclusionsOverall, ATA3271 shows potent anti-tumor activity without evidence of allotoxicity, both in vitro and in vivo, suggesting that allogeneic MSLN-CAR-engineered EBV T cells are a promising approach for the treatment of MSLN-positive cancers and warrant further clinical investigation.ReferencesAdusumilli PS, Zauderer MG, Rusch VW, et al. Abstract CT036: A phase I clinical trial of malignant pleural disease treated with regionally delivered autologous mesothelin-targeted CAR T cells: Safety and efficacy. Cancer Research 2019;79:CT036-CT036.Kiesgen S, Linot C, Quach HT, et al. Abstract LB-378: Regional delivery of clinical-grade mesothelin-targeted CAR T cells with cell-intrinsic PD-1 checkpoint blockade: Translation to a phase I trial. Cancer Research 2020;80:LB-378-LB-378.Prockop S, Doubrovina E, Suser S, et al. Off-the-shelf EBV-specific T cell immunotherapy for rituximab-refractory EBV-associated lymphoma following transplantation. J Clin Invest 2020;130:733–747.Prockop S, Hiremath M, Ye W, et al. A Multicenter, Open Label, Phase 3 Study of Tabelecleucel for Solid Organ Transplant Subjects with Epstein-Barr Virus-Driven Post-Transplant Lymphoproliferative Disease (EBV+PTLD) after Failure of Rituximab or Rituximab and Chemotherapy. Blood 2019; 134: 5326–5326.Curran KJ, Sauter CS, Kernan NA, et al. Durable remission following ‘Off-the-Shelf’ chimeric antigen receptor (CAR) T-Cells in patients with relapse/refractory (R/R) B-Cell malignancies. Biology of Blood and Marrow Transplantation 2020;26:S89.

scholarly journals Switch receptor T3/28 improves long-term persistence and antitumor efficacy of CAR-T cells

2021 ◽  
Vol 9 (12) ◽  
pp. e003176
Author(s):  
Songbo Zhao ◽  
Chunhua Wang ◽  
Ping Lu ◽  
Yalin Lou ◽  
Huimin Liu ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Antitumor Activity ◽  
Lymphoid Leukemia ◽  
T Cell Therapy ◽  
Cell Therapies ◽  
Car T Cells ◽  
Car T

BackgroundChimeric antigen receptor (CAR) T cells have been successfully used in tumor immunotherapy due to their strong antitumor responses, especially in hematological malignancies such as B cell acute lymphoid leukemia. However, on-target off-tumor toxicity and poor persistence severely limit the clinical application of CAR-T cell therapy.MethodsT-cell immunoglobulin mucin domain molecule 3 (TIM-3) was used to develop a second-generation 41BB CD19 CAR linked with a T3/28 chimera, in which truncated extracellular TIM-3 was fused with the CD28 transmembrane and cytoplasmic domains. The efficacy of T3/28 CAR-T cells was evaluated in vitro and in vivo.ResultsWe demonstrated that the switch receptor T3/28 preserved the TCM phenotype, improved proliferative capacity, and reduced exhaustion of CAR-T cells, resulting in superior in vitro and in vivo antitumor activity in B lymphoma. Importantly, the switch receptor T3/28 substantially prolonged the persistence of CAR-T cells, and the interleukin-21/Stat3 axis probably contributed to the enhanced cytotoxicity of T3/28 CAR-T cells.ConclusionOverall, the T3/28 chimera significantly prolonged the persistence of CAR-T cells, and T3/28 CAR-T cells possessed potent antitumor activity in mice, shedding new light on potential improvements in adoptive T cell therapies.

scholarly journals 124 Functionalizing CAR T cells for selective proliferation and dual-targeting using the meditope technology

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A133-A133
Author(s):  
Cheng-Fu Kuo ◽  
Yi-Chiu Kuo ◽  
Miso Park ◽  
Zhen Tong ◽  
Brenda Aguilar ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Therapy ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T Cell Therapy ◽  
Car T

BackgroundMeditope is a small cyclic peptide that was identified to bind to cetuximab within the Fab region. The meditope binding site can be grafted onto any Fab framework, creating a platform to uniquely and specifically target monoclonal antibodies. Here we demonstrate that the meditope binding site can be grafted onto chimeric antigen receptors (CARs) and utilized to regulate and extend CAR T cell function. We demonstrate that the platform can be used to overcome key barriers to CAR T cell therapy, including T cell exhaustion and antigen escape.MethodsMeditope-enabled CARs (meCARs) were generated by amino acid substitutions to create binding sites for meditope peptide (meP) within the Fab tumor targeting domain of the CAR. meCAR expression was validated by anti-Fc FITC or meP-Alexa 647 probes. In vitro and in vivo assays were performed and compared to standard scFv CAR T cells. For meCAR T cell proliferation and dual-targeting assays, the meditope peptide (meP) was conjugated to recombinant human IL15 fused to the CD215 sushi domain (meP-IL15:sushi) and anti-CD20 monoclonal antibody rituximab (meP-rituximab).ResultsWe generated meCAR T cells targeting HER2, CD19 and HER1/3 and demonstrate the selective specific binding of the meditope peptide along with potent meCAR T cell effector function. We next demonstrated the utility of a meP-IL15:sushi for enhancing meCAR T cell proliferation in vitro and in vivo. Proliferation and persistence of meCAR T cells was dose dependent, establishing the ability to regulate CAR T cell expansion using the meditope platform. We also demonstrate the ability to redirect meCAR T cells tumor killing using meP-antibody adaptors. As proof-of-concept, meHER2-CAR T cells were redirected to target CD20+ Raji tumors, establishing the potential of the meditope platform to alter the CAR specificity and overcome tumor heterogeneity.ConclusionsOur studies show the utility of the meCAR platform for overcoming key challenges for CAR T cell therapy by specifically regulating CAR T cell functionality. Specifically, the meP-IL15:sushi enhanced meCAR T cell persistence and proliferation following adoptive transfer in vivo and protects against T cell exhaustion. Further, meP-ritiuximab can redirect meCAR T cells to target CD20-tumors, showing the versatility of this platform to address the tumor antigen escape variants. Future studies are focused on conferring additional ‘add-on’ functionalities to meCAR T cells to potentiate the therapeutic effectiveness of CAR T cell therapy.

scholarly journals Targeting glycosylation of PD-1 to enhance CAR-T cell cytotoxicity

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Xiaojuan Shi ◽  
Daiqun Zhang ◽  
Feng Li ◽  
Zhen Zhang ◽  
Shumin Wang ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Inhibitory Effects ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T Cell Therapy ◽  
Car T

AbstractAsparagine-linked (N-linked) glycosylation is ubiquitous and can stabilize immune inhibitory PD-1 protein. Reducing N-linked glycosylation of PD-1 may decrease PD-1 expression and relieve its inhibitory effects on CAR-T cells. Considering that the codon of Asparagine is aac or aat, we wondered if the adenine base editor (ABE), which induces a·t to g·c conversion at specific site, could be used to reduce PD-1 suppression by changing the glycosylated residue in CAR-T cells. Our results showed ABE editing altered the coding sequence of N74 residue of PDCD1 and downregulated PD-1 expression in CAR-T cells. Further analysis showed ABE-edited CAR-T cells had enhanced cytotoxic functions in vitro and in vivo. Our study suggested that the single base editors can be used to augment CAR-T cell therapy.

scholarly journals Efficient elimination of primary B-ALL cells in vitro and in vivo using a novel 4-1BB-based CAR targeting a membrane-distal CD22 epitope

2020 ◽  
Vol 8 (2) ◽  
pp. e000896
Author(s):  
Talia Velasco-Hernandez ◽  
Samanta Romina Zanetti ◽  
Heleia Roca-Ho ◽  
Francisco Gutierrez-Aguera ◽  
Paolo Petazzi ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Therapy ◽  
T Cell Therapy ◽  
High Affinity ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T

BackgroundThere are few therapeutic options available for patients with B-cell acute lymphoblastic leukemia (B-ALL) relapsing as CD19– either after chemotherapy or CD19-targeted immunotherapies. CD22-chimeric antigen receptor (CAR) T cells represent an attractive addition to CD19-CAR T cell therapy because they will target both CD22+CD19– B-ALL relapses and CD19– preleukemic cells. However, the immune escape mechanisms from CD22-CAR T cells, and the potential contribution of the epitope binding of the anti-CD22 single-chain variable fragment (scFv) remain understudied.MethodsHere, we have developed and comprehensively characterized a novel CD22-CAR (clone hCD22.7) targeting a membrane-distal CD22 epitope and tested its cytotoxic effects against B-ALL cells both in in vitro and in vivo assays.ResultsConformational epitope mapping, cross-blocking, and molecular docking assays revealed that the hCD22.7 scFv is a high-affinity binding antibody which specifically binds to the ESTKDGKVP sequence, located in the Ig-like V-type domain, the most distal domain of CD22. We observed efficient killing of B-ALL cells in vitro, although the kinetics were dependent on the level of CD22 expression. Importantly, we show an efficient in vivo control of patients with B-ALL derived xenografts with diverse aggressiveness, coupled to long-term hCD22.7-CAR T cell persistence. Remaining leukemic cells at sacrifice maintained full expression of CD22, ruling out CAR pressure-mediated antigen loss. Finally, the immunogenicity capacity of this hCD22.7-scFv was very similar to that of other CD22 scFv previously used in adoptive T cell therapy.ConclusionsWe report a novel, high-affinity hCD22.7 scFv which targets a membrane-distal epitope of CD22. 4-1BB-based hCD22.7-CAR T cells efficiently eliminate clinically relevant B- CD22high and CD22low ALL primary samples in vitro and in vivo. Our study supports the clinical translation of this hCD22.7-CAR as either single or tandem CD22–CD19-CAR for both naive and anti-CD19-resistant patients with B-ALL.

scholarly journals 133 CRISPR/Cas9 gene-edited allogeneic CAR-T cells targeting CD33 show high preclinical efficacy against AML without long-term hematopoietic toxicity

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A143-A143
Author(s):  
Jonathan Terrett ◽  
Brigid Mcewan ◽  
Daniel Hostetter ◽  
Luis Gamboa ◽  
Meghna Kuppuraju ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Antibody Drug Conjugate ◽  
T Cell Therapy ◽  
In Vivo Models ◽  
Car T Cells ◽  
Car T

BackgroundCD33 is the most consistently expressed antigen in AML, with high levels and homogeneous expression observed in malignant AML cells from most patients, including those with relapsed disease. Normal myelomonocytic cell lineages and a percentage of hematopoietic progenitors also express CD33, and the extreme myeloablation caused by the CD33-targeted antibody-drug conjugate (ADC) gemtuzumab ozogamicin reinforced concerns about targeting this antigen with more potent agents such as T-cell engaging bispecific antibodies and CAR-T cells. We have shown previously that allogeneic CRISPR/Cas9 gene-edited CAR-T cells targeting CD33 with TRAC disruption to reduce GvHD and B2M disruption to reduce allogeneic host rejection could eliminate tumors in xenograft models of AMLMethodsGiven that off-target activity of the toxin could contribute to the myeloablation seen with CD33-targeted ADCs, we created in vitro and in vivo models to examine reconstitution of the myeloid compartment following treatment of CD33-targeted allogeneic CAR-T cells.ResultsAlthough co-culture of CD34+ stem cells in vitro with our CD33-targeted allogeneic CAR-T cells did significantly deplete the cell population, colonies still formed after removal of the CAR-T cells as the presumably CD33-negative stem/progenitor cells expanded and differentiated. A similar phenomenon was observed in vivo with CD34 humanized mice bearing an AML tumor (THP-1 cells) and treated with the CD33-targeted allogeneic CAR-T cells. The CAR-T cells completely eradicated the THP-1 tumor but did not lead to long-term myelosuppression or B cell aplasia.ConclusionsThus, allogeneic CRISPR/Cas9 multiplex gene-edited CD33-targeted CAR-T cell therapy may be both efficacious and tolerable in AML.

scholarly journals 126 Regional administration of IL-12 endowed CAR T cells effectively targets systemic disease

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A135-A135
Author(s):  
Hee Jun Lee ◽  
Cody Cullen ◽  
John Murad ◽  
Jason Yang ◽  
Wen-Chung Chang ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
T Cells ◽  
T Cell ◽  
Tumor Models ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T

BackgroundWhile chimeric antigen receptor (CAR) T cell therapy has shown impressive clinical efficacy for hematological malignancies,1 efficacy remains limited for solid tumors due in large part to the immunosuppressive tumor microenvironment.2 Tumor-associated glycoprotein 72 (TAG72) is an aberrantly glycosylated protein overexpressed on ovarian cancer3 and is an exciting target for CAR T cell immunotherapy. Our lab previously developed a second-generation TAG72 CAR T cell product and showed its potency against TAG72-expressing ovarian tumor cells both in vitro and in preclinical mouse models.4 We report here further modification of our TAG72 CAR T cells, with incorporation of interleukin-12 (IL-12) and interleukin-15 (IL-15), and evaluate the therapeutic benefits in peritoneal ovarian tumor models.MethodsIn this preclinical study, we build upon our earlier work with in vitro and in vivo evaluation of 9 different second-generation TAG72 CAR constructs varying in single-chain variable fragment, extracellular spacer, transmembrane, and intracellular co-stimulatory domains. We then engineer CAR T cells with two types of cytokines – IL-12 and IL-15 – and put these engineered cells against challenging in vivo tumor models.ResultsThrough in vitro and in vivo studies, we identify the most optimal construct with which we aim to evaluate in a phase 1 clinical trial targeting TAG72-positive ovarian cancer in 2021. Despite thorough optimizations to the CAR backbone, CAR T cells can be additionally engineered for improved anti-tumor response. Therefore, we further engineered CAR T cells with IL-12 or IL-15 production that greatly improves the effectiveness of TAG72-CAR T cells in difficult-to-treat in vivo tumor models. We observed that modification of CAR T cells with IL-15 displayed toxicity when regionally delivered in vivo, yet introduction of IL-12 not only demonstrated safe and superior therapeutic responses, but also allowed the regional administration of CAR T cells to address systemic disease. We are now expanding these findings by evaluating these therapies using syngeneic immunocompetent mouse tumor models.ConclusionsThe tumor microenvironment (TME) harbors various factors that thwart the killing of tumor cells by CAR T cells. Thus, CAR T cells will likely require further engineering to overcome this barrier. We show that amplifying cytokine pathways is one way to overcome the TME and improve the efficacy of CAR T cell therapy for solid tumors.ReferencesMaude SL, Teachey DT, Porter DL, Grupp SA. CD19-targeted chimeric antigen receptor T-cell therapy for acute lymphoblastic leukemia. Blood 2015 Jun 25;125(26):4017–23.Priceman SJ, Forman SJ, Brown CE. Smart CARs engineered for cancer immunotherapy. Curr Opin Oncol 2015 Nov;27(6):466–74.Chauhan SC, Vinayek N, Maher DM, Bell MC, Dunham KA, Koch MD, Lio Y, Jaggi M. Combined Staining of TAG-72, MUC1, and CA125 Improves Labeling Sensitivity in Ovarian Cancer: Antigens for Multi-targeted Antibody-guided Therapy. J Histochem Cytochem 2007 Aug;55(8):867–75.Murad JP, Kozlowska AK, Lee HJ, Ramamurthy M, Chang WC, Yazaki P, Colcher D, Shively J, Cristea M, Forman SJ, Priceman SJ. Effective Targeting of TAG72+ Peritoneal Ovarian Tumors via Regional Delivery of CAR-Engineered T Cells. Front Immunol 2018 Nov 19;9:2268.

scholarly journals 137 Development of anti-Mucin1 CAR-T against solid tumors

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A146-A146
Author(s):  
Jihyun Lee ◽  
Areum Park ◽  
Jungwon Choi ◽  
Dae Gwan Yi ◽  
Hee Jung Yang ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Solid Tumors ◽  
Cell Therapies ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T ◽  
Anti Tumor Activity

BackgroundChimeric antigen receptor (CAR) -T cell therapies have proven to be effective against various liquid tumors. However, the development of CAR-T against solid tumors has been challenging due to insufficient efficacy and potential on-target off-tumor toxicities caused by low expression of tumor antigens on normal tissues. Testing various affinities of CARs has demonstrated that lower affinity CARs maintain its anti-tumor effect while minimizing safety concerns (1). In order to develop a CAR-T against solid tumors expressing Mucin1, we have screened for Mucin1 binding antibodies and tested their anti-tumor effect in vitro and in vivo. The potential of on-target off-tumor toxicity was also measured in vitro.MethodsAnti-Mucin1 human single chain variable fragments (scFv) were obtained via screening against a scFv display library. Anti-Mucin1 scFvs were incorporated into CARs and in vitro, in vivo functions against various tumor cells expressing Mucin1 were tested. For in vivo studies, tumor bearing NOG mice (HCC1954 cells) received anti-Mucin1 CAR-T cells. Therapeutic efficacy was evaluated by measuring tumor volumes. Potential on-target off-tumor toxicity against Mucin1 on normal cells was tested by investigating the killing effect of anti-Mucin1 CAR-T against cancer cell line (HCC70) and non-tumorigenic breast epithelial cell line (MCF-10A) in co-culture systemsResultsIn vitro activity of anti-Mucin1 CAR-T cells that displayed a range of affinities for Mucin1 (27nM to 320nM) showed similar cytokine secretion levels and cytotoxicity against Mucin-1 expressing tumor cell lines (HCC70 and T47D). Robust anti-tumor activity was also demonstrated in vivo against large tumors (400~500 mm3) with relatively small numbers of CAR-T cells (0.5 x 106 CAR-T cells per mouse). In vivo expansion of CAR-T cells were observed in all scFv-CAR-T cases and accompanied by close to complete regression of tumors within 25 days post CAR-T cell injection. Of the 4 scFv CAR-Ts, 2H08 (with a Kd of 94nM) was tested for activity against normal breast epithelial cells. When 2H08-CAR-T was cocultured with a mixture of HCC70 and MCF-10A cells, they preferentially killed only the Mucin1 overexpressing HCC70 cells leaving MCF-10 cells intact.ConclusionsOur study demonstrates anti-tumor activity of a novel scFv-derived CAR-T recognizing Mucin1 and its effectiveness in large pre-established tumors in vivo. We also demonstrate that 2H08-CAR-T can distinguish between target overexpressing cancer cells and normal epithelial cells, which suggests that by toning down the affinity of CAR against antigen one can improve the safety profile of solid tumor antigen targeting CAR-T cell therapies.ReferenceCastellarin M, Sands C, Da T, Scholler J, Graham K, Buza E, Fraietta J, Zhao Y, June C. A rational mouse model to detect on-target, off-tumor CAR T cell toxicity. JCI Insight 2020; 5:e136012Ethics ApprovalAll experiments were done under protocols approved by the Institutional Animal Care and Use Committee (IACUC) (Study#LGME21-011).ConsentWritten informed consent was obtained from the patient for publication of this abstract and any accompanying images. A copy of the written consent is available for review by the Editor of this journal.

scholarly journals Counteracting CAR T cell dysfunction

Oncogene ◽  
2020 ◽  
Author(s):  
Mansour Poorebrahim ◽  
Jeroen Melief ◽  
Yago Pico de Coaña ◽  
Stina L. Wickström ◽  
Angel Cid-Arregui ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Adoptive Cell Transfer ◽  
T Cell Therapy ◽  
Cell Therapies ◽  
Safety Issues ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T

Abstract In spite of high rates of complete remission following chimeric antigen receptor (CAR) T cell therapy, the efficacy of this approach is limited by generation of dysfunctional CAR T cells in vivo, conceivably induced by immunosuppressive tumor microenvironment (TME) and excessive antigen exposure. Exhaustion and senescence are two critical dysfunctional states that impose a pivotal hurdle for successful CAR T cell therapies. Recently, modified CAR T cells with an “exhaustion-resistant” phenotype have shown superior antitumor functions and prolonged lifespan. In addition, several studies have indicated the feasibility of senescence delay in CAR T cells. Here, we review the latest reports regarding blockade of CAR T cell exhaustion and senescence with a particular focus on the exhaustion-inducing pathways. Subsequently, we describe what potential these latest insights offer for boosting the potency of adoptive cell transfer (ACT) therapies involving CAR T cells. Furthermore, we discuss how induction of costimulation, cytokine exposure, and TME modulation can impact on CAR T cell efficacy and persistence, while potential safety issues associated with reinvigorated CAR T cells will also be addressed.

scholarly journals 136 ATA3271: An armored, next-generation off-the-shelf, allogeneic, mesothelin-CAR T cell therapy for solid tumors

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A145-A145
Author(s):  
Xianhui Chen ◽  
Jiangyue Liu ◽  
Shuai Yang ◽  
Amogh Oke ◽  
Sarah Davies ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Therapy ◽  
Next Generation ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T Cell Therapy ◽  
Car T

BackgroundMesothelin (MSLN) is a GPI-anchored membrane protein with high expression levels in an array of malignancies including mesothelioma and is an attractive target antigen for tumor surface antigen-targeting therapies. Regional administration of autologous, 2nd generation MSLN-targeted CAR-T cells for malignant pleural mesothelioma has shown promise in early clinical evaluation.1 2 More recently, a next-generation MSLN-targeted, autologous CAR T therapy leveraging 1XX CAR signaling and PD1DNR is currently under investigation for advanced mesothelioma [NCT04577326]. Although autologous MSLN CAR-T holds promise, an allogeneic approach may have more widespread application. EBV T-cells represent a unique, non-gene edited approach for allogeneic T-cell therapy. EBV-specific T-cells are currently in a phase 3 trial for EBV-positive post-transplant lymphoproliferative disease [NCT03394365] and, to-date, have demonstrated a favorable safety profile with no evidence for GvHD and cytokine release syndrome attributable to EBV T-cells. Clinical proof-of-principle studies for CAR transduced CD19-targeted allogeneic EBV T-cell therapies have shown acceptable safety and durable response.3 The first preclinical evaluation of ATA3271 was reported last year.4 Here, we describe updated preclinical data for this potential off-the-shelf, allogeneic cell therapy.MethodsWe engineered MSLN CAR+ EBV T-cells (ATA3271) with a novel 1XX signaling domain that is associated with strong effector function and favorable persistence, as well as armored with PD1DNR to provide intrinsic checkpoint blockade.5 Anti-tumor effect of ATA3271 was assessed using a MSTO-211H-derived tumor cell line overexpressing MSLN and PDL1.ResultsUpon MSLN engagement, ATA3271 showed proliferation, efficient tumor cell lysis in the presence of high-level cell-surface PD-L1 expression and secretion of effector cytokines [IL-2, TNF-α, granzyme B]. In a 16-day serial stimulation assay, with PD-L1+ tumor cells added every 2–3 days, ATA3271 expanded 4 to 45-fold without the need for external cytokines, and retained comparable antitumor function as CD3/CD28-stimulated ‘autologous’ CAR-T cells. In an orthotopic mouse model of pleural mesothelioma, ATA3271 demonstrated anti-tumor efficacy without toxicities. Memory markers [CD62L, CCR7] play a key role for T-cell persistence in vivo. We identified donor-to-donor variability in memory marker expression on ATA3271 and optimized our process to maximize their expression. Memory marker expression impact on ATA3271 potency, both in vitro and in vivo, will be presented.ConclusionsOverall, these in vitro and in vivo data show potent anti-tumor activity without evidence of toxicity, suggesting that ATA3271 may be a promising approach for the treatment of MSLN-positive cancers that warrants further clinical investigation.ReferencesAdusumilli Prasad S, et al. Abstract CT036: A phase I clinical trial of malignant pleural disease treated with regionally delivered autologous mesothelin-targeted CAR T cells: Safety and efficacy. Cancer Res 2019;79(13 Suppl):Abstract CT036.Adusumilli Prasad S, et al. A phase I trial of regional mesothelin-targeted CAR T-cell therapy in patients with malignant pleural disease, in combination with the anti-PD-1 agent pembrolizumab. Cancer Discov 2021.Curran Kevin J, et al. Durable remission following ‘off-the-shelf’ chimeric antigen receptor (CAR) T-cells in patients with relapse/refractory (R/R) B-cell malignancies. Biol Blood Marrow Transplant 2020;26.3: S89.Liu Jiangyue, et al. 98 ATA3271: an armored, next-generation off-the-shelf, allogeneic, mesothelin-CAR T cell therapy for solid tumors. JITC 2020;8.Feucht Judith, et al. Calibration of CAR activation potential directs alternative T cell fates and therapeutic potency. Nat Med 2019;25.1: 82–88.

scholarly journals The Transferrin Receptor-Directed CAR for the Therapy of Hematologic Malignancies

2021 ◽  
Vol 12 ◽  
Author(s):  
Zilong Guo ◽  
Yirui Zhang ◽  
Mingpeng Fu ◽  
Liang Zhao ◽  
Zhen Wang ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Transferrin Receptor ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Therapy Strategy ◽  
Car T

As many patients ultimately relapse after chimeric antigen receptor (CAR) T-cell therapy, identification of alternative targets is currently being evaluated. Substantial research efforts are underway to develop new targets. The transferrin receptor (TfR) is prevalently expressed on rapidly proliferating tumor cells and holds the potential to be the alternative target. In order to investigate the efficacy and challenges of TfR-targeting on the CAR-based therapy strategy, we generated a TfR-specific CAR and established the TfR-CAR–modified T cells. To take the advantage of TfR being widely shared by multiple tumors, TfR-CAR T cells were assessed against several TfR+ hematological malignant cell lines. Data showed that TfR-CAR T cells were powerfully potent in killing all these types of cells in vitro and in killing T-ALL cells in vivo. These findings suggest that TfR could be a universal target to broaden and improve the therapeutic efficacy of CAR T cells and warrant further efforts to use these cells as an alternative CAR T cell product for the therapy of hematological malignancies.

Sign in / Sign up

Export Citation Format

Share Document