A Tet-On Inducible System for Controlling CD19-Chimeric Antigen Receptor Expression upon Drug Administration

Context.— Chimeric antigen receptor T-cell (CAR-T) technology has shown great promise in both clinical and preclinical models in mediating potent and specific antitumor activity. With the advent of US Food and Drug Administration–approved CAR-T therapies for B-cell lymphoblastic leukemia and B-cell non-Hodgkin lymphomas, CAR-T therapy is poised to become part of mainstream clinical practice. Objective.— To educate pathologists on CAR-T and chimeric antigen receptor–derived cellular therapy, provide a better understanding of their role in this process, explain important regulatory aspects of CAR-T therapy, and advocate for pathologist involvement in the delivery and monitoring of chimeric antigen receptor–based treatments. Much of the focus of this article addresses US Food and Drug Administration–approved therapies; however, more general issues and future perspectives are considered for therapies in development. Design.— A CAR-T workgroup, facilitated by the College of American Pathologists Personalized Health Care Committee and consisting of pathologists of various backgrounds, was convened to develop a summary guidance paper for the College of American Pathologists Council on Scientific Affairs. Results.— The workgroup identified gaps in pathologists' knowledge of CAR-T therapy, including uncertainty in the role of the clinical laboratory in supporting CAR-T therapy. The workgroup considered these issues and summarized the findings to assist pathologists to become stakeholders in CAR-T therapy administration. Conclusions.— This manuscript serves to both educate pathologists on CAR-T therapy and serve as a point of initial discussions in areas of CAR-T science, clinical therapy, and regulatory issues as CAR-T therapies continue to be introduced into clinical practice.

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EXTH-32. DEVELOPMENT OF EPHA3 DIRECTED CHIMERIC ANTIGEN RECEPTOR T CELL THERAPY FOR THE TREATMENT OF GLIOBLASTOMA MULTIFORME

Neuro-Oncology ◽

10.1093/neuonc/noz175.364 ◽

2019 ◽

Vol 21 (Supplement_6) ◽

pp. vi88-vi89 ◽

Cited By ~ 1

Author(s):

Michael Ruff ◽

Reona Sakemura ◽

Michelle Cox ◽

Mehrdad Hefazi Torghabeh ◽

Paulina Roman Moreno ◽

...

Keyword(s):

T Cell ◽

Solid Tumors ◽

Cell Lines ◽

Chimeric Antigen Receptor ◽

Stromal Cells ◽

Antigen Receptor ◽

Receptor Expression ◽

Eph Receptors ◽

Single Chain ◽

Tumor Neovasculature

Abstract BACKGROUND Efficacy of chimeric antigen receptor T cell (CART) therapy remains limited in solid tumors. Given the heterogeneity of surface receptor expression and immunosuppressive stromal microenvironment, strategies to target tumor neovasculature and tumor stromal cells are needed to help overcome CART inhibition by GBM. Eph receptors are the largest family of receptor tyrosine kinases and are integral to cell adhesion, migration, and axon guidance, during development and homeostasis. EphA3 is a receptor tyrosine kinase which is lowly expressed in adult tissues but is highly expressed in tumor neovasculature and tumor stromal cells in GBM and other solid tumors. EphA3 is over-expressed in up to 40% of GBM samples. We aimed to develop CART cells directed against EphA3 to use in targeting tumor neovasculature and tumor stromal cells in GBM. METHODS we developed a second generation CD28 co-stimulated CAR construct in a third generation lentivirus backbone to generate EphA3 CART cells using the single chain variable fragment of ifabotuzumab, a monoclonal antibody directed against EphA3. Patient derived GBM xenograft cell lines were used in these experiments. RESULTS EphA3 directed CART cells exhibited specific and potent antitumor activity against EphA3+ GBM cell lines with variable transcriptome EphA3 expression indicating its broader applicability in patients with GBM. Killing over 24-hour incubation was significant at low effector: target ratio: 52.5% killing at 1.25:1 against cell lines with 25.05% EphA3 expression and 37.1% killing at 1.25:1and 90% killing at 5:1 ratio against a cell line with 19.28% expression. Conversely, when co-cultured with UTD controls there was significantly lower killing, or growth of tumor cells. CONCLUSION We demonstrate for the first time that targeting EphA3 with CART cells is feasible, efficacious and represents a novel therapeutics strategy to target GBM. Data from in vivo and combinatorial CART experiments will be reported at the meeting.

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Disease Burden Affects Outcomes in Pediatric and Young Adult B-Cell Lymphoblastic Leukemia After Commercial Tisagenlecleucel: A Pediatric Real-World Chimeric Antigen Receptor Consortium Report

Journal of Clinical Oncology ◽

10.1200/jco.20.03585 ◽

2021 ◽

Author(s):

Liora M. Schultz ◽

Christina Baggott ◽

Snehit Prabhu ◽

Holly L. Pacenta ◽

Christine L. Phillips ◽

...

Keyword(s):

Bone Marrow ◽

B Cell ◽

Drug Administration ◽

Chimeric Antigen Receptor ◽

Disease Burden ◽

Lymphoblastic Leukemia ◽

Food And Drug Administration ◽

Antigen Receptor ◽

Response Analysis ◽

Intent To Treat

PURPOSE Tisagenlecleucel is a CD19-specific chimeric antigen receptor T-cell therapy, US Food and Drug Administration–approved for children, adolescents, and young adults (CAYA) with relapsed and/or refractory (RR) B-cell acute lymphoblastic leukemia (B-ALL). The US Food and Drug Administration registration for tisagenlecleucel was based on a complete response (CR) rate of 81%, 12-month overall survival (OS) of 76%, and event-free survival (EFS) of 50%. We report clinical outcomes and analyze covariates of outcomes after commercial tisagenlecleucel. METHODS We conducted a retrospective, multi-institutional study of CAYA with RR B-ALL across 15 US institutions, who underwent leukapheresis shipment to Novartis for commercial tisagenlecleucel. A total of 200 patients were included in an intent-to-treat response analysis, and 185 infused patients were analyzed for survival and toxicity. RESULTS Intent-to-treat analysis demonstrates a 79% morphologic CR rate (95% CI, 72 to 84). The infused cohort had an 85% CR (95% CI, 79 to 89) and 12-month OS of 72% and EFS of 50%, with 335 days of median follow-up. Notably, 48% of patients had low-disease burden (< 5% bone marrow lymphoblasts, no CNS3, or other extramedullary disease), or undetectable disease, pretisagenlecleucel. Univariate and multivariate analyses associate high-disease burden (HB, ≥ 5% bone marrow lymphoblasts, CNS3, or non-CNS extramedullary) with inferior outcomes, with a 12-month OS of 58% and EFS of 31% compared with low-disease burden (OS; 85%, EFS; 70%) and undetectable disease (OS; 95%, EFS; 72%; P < .0001 for OS and EFS). Grade ≥ 3 cytokine release syndrome and neurotoxicity rates were 21% and 7% overall and 35% and 9% in patients with HB, respectively. CONCLUSION Commercial tisagenlecleucel in CAYA RR B-ALL demonstrates efficacy and tolerability. This first analysis of commercial tisagenlecleucel stratified by disease burden identifies HB preinfusion to associate with inferior OS and EFS and increased toxicity.

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DDRE-18. DEVELOPMENT OF EGFRvIII AND EGFR DIRECTED CHIMERIC ANTIGEN RECEPTOR T CELL THERAPY FOR THE TREATMENT OF GLIOBLASTOMA MULTIFORME

Neuro-Oncology ◽

10.1093/neuonc/noaa215.263 ◽

2020 ◽

Vol 22 (Supplement_2) ◽

pp. ii65-ii65

Author(s):

Michael Ruff ◽

Reona Sakemura ◽

Claudia Manriquez-Roman ◽

Mehrdad Hefazi-Torghabeh ◽

Kendall Schick ◽

...

Keyword(s):

T Cell ◽

Tumor Cells ◽

Cell Lines ◽

Chimeric Antigen Receptor ◽

Tumor Antigens ◽

Antigen Receptor ◽

Receptor Expression ◽

T Cell Therapy ◽

Multiple Tumor

Abstract BACKGROUND Chimeric antigen receptor T cell (CART) therapy has revolutionized the treatment landscape for hematological malignancies, its efficacy remains limited in solid tumors. EGFRvIII is a truncated version of the wild type EGFR in which deletion of exons 2–7 of the extracellular domain leads the variant (EGFRvIII) that is strongly antigenic and is mostly expressed on tumor cells. EGFR amplification (tEGFR) almost uniformly precedes the presence of EGFRvIII on tumor cells. The heterogeneity of surface receptor expression and immunosuppressive stromal microenvironment underscore the need to develop CART strategies to target multiple tumor antigens simultaneously. METHODS we generated tEGFR/EGFRvIII directed CAR construct by cloning a clinically relevant tEGFR and EGFRvIII specific scFv into a second generation CAR construct (41BB stimulated) in a third generation lentivirus backbone. This was used to transfect 293T cells and the generated lentivirus particles were used to transduce T cells and generate EGFRvIII/tEGFR CART cells. GBM primary patient derived cell lines were used in these experiments. These cells were passaged and maintained in patient derived xenograft models. RESULTS EGFRvIII/tEGFR directed CART cells exhibited potent antitumor activity against EGFRvIII/tEGFR + GBM cell lines: with 100% killing at 1.25:1, 2.5:1, 5:1 and 10:1 E:T ratio on multiple PDX cell lines with EGFRvIII expression and EGFR over-expression (greater than five copies of EGFR gene) at 24 hours of incubation. Conclusion: We demonstrate that targeting EGFRvIII and over-expressed EGFR with CART cells is feasible, efficacious and represents a promising therapeutic strategy to target GMB. Data from in vivo and combinatorial CART experiments will be reported at the meeting.

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