dynamic-imaging-chimeric-antigen-receptor-t-cells-with

Dynamic Imaging of Chimeric Antigen Receptor T Cells with [<sup>18</sup>F]Tetrafluoroborate Positron Emission Tomography/Computed Tomography

T cells genetically engineered to express chimeric antigen receptors (CAR) have shown unprecedented results in pivotal clinical trials for patients with B ...

assessment-chimeric-antigen-receptor-t-cell-associated-toxicities

Assessment of Chimeric Antigen Receptor T Cell-Associated Toxicities Using an Acute Lymphoblastic Leukemia Patient-Derived Xenograft Mouse Model

Chimeric antigen receptor T (CART) cell therapy has emerged as a powerful tool for the treatment of multiple types of CD19+ malignancies, which has led to ...

Mayo Clinic

Mayo Clinic, Rochester

Chimeric antigen receptors (CARs) are engineered receptors that mediate T cell activation. CARs are comprised of activating and co-stimulatory intracellular signaling domains derived from endogenous T cells that initiate signaling required for T cell activation, including ERK activation through the MAPK pathway. Understanding the mechanisms by which co-stimulatory domains influence signaling can help guide the design of next-generation CARs. Therefore, we constructed an experimentally validated computational model of anti-CD19 CARs in T cells bearing the CD3ζ domain alone or in combination with CD28. We performed a systematic analysis to explore the different mechanisms of CD28 co-stimulation on the ERK response time. Comparing these model simulations with experimental data indicates that CD28 primarily influences ERK activation by enhancing the phosphorylation kinetics of CD3ζ. Overall, we present a mechanistic mathematical modeling framework that can be used to gain insights into the mechanism of CAR T cell activation and produce new testable hypotheses.

ERK Activation in CAR T Cells Is Amplified by CD28-Mediated Increase in CD3ζ Phosphorylation.

Chimeric antigen receptor T (CART) cell immunotherapy has been remarkably successful in treating certain relapsed/refractory hematological cancers. However, CART cell therapy is also associated with toxicities which present an obstacle to its wider adoption as a mainstay for cancer treatment. The primary toxicities following CART cell administration are cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS). New insights into the mechanisms of these toxicities have spurred novel treatment options. In this review, we summarize the available literature on the clinical manifestations, mechanisms, and treatments of CART-associated CRS and ICANS.

Neurotoxicity and Cytokine Release Syndrome After Chimeric Antigen Receptor T Cell Therapy: Insights Into Mechanisms and Novel Therapies.

Chimeric antigen receptor-engineered T (CAR-T) cell immunotherapy has been successful in treating many types of hematological malignancies. CAR-T therapy, however, has been associated with toxicities, including cytokine release syndrome (CRS) as well as immune effector cell-associated neurotoxicity syndrome (ICANS). ICANS presentation is variable, largely reversible, and manifests with encephalopathy and focal neurologic deficits. Treatment strategies largely are supportive. ICANS pathophysiology likely is related to that of CRS. Preclinical studies and clinical experience have shed light on the driving forces of ICANS and have yielded new strategies to mitigate ICANS occurrence.

A Concise Review of Neurologic Complications Associated with Chimeric Antigen Receptor T-cell Immunotherapy.

Chimeric antigen receptor (CAR) T cell therapy has yielded unprecedented outcomes in some patients with hematological malignancies; however, inhibition by the tumor microenvironment has prevented the broader success of CART cell therapy. We used chronic lymphocytic leukemia (CLL) as a model to investigate the interactions between the tumor microenvironment and CART cells. CLL is characterized by an immunosuppressive microenvironment, an abundance of systemic extracellular vesicles (EVs), and a relatively lower durable response rate to CART cell therapy. In this study, we characterized plasma EVs from untreated CLL patients and identified their leukemic cell origin. CLL-derived EVs were able to induce a state of CART cell dysfunction characterized by phenotypical, functional, and transcriptional changes of exhaustion. We demonstrate that, specifically, PD-L1 CLL-derived EVs induce CART cell exhaustion. In conclusion, we identify an important mechanism of CART cell exhaustion induced by EVs from CLL patients.

Leukemic extracellular vesicles induce chimeric antigen receptor T cell dysfunction in chronic lymphocytic leukemia.

T cells genetically engineered with chimeric antigen receptors (CART) have become a potent class of cancer immunotherapeutics. Numerous clinical trials of CART cells have revealed remarkable remission rates in patients with relapsed or refractory hematologic malignancies. Despite recent clinical success, CART cell therapy has also led to significant morbidity and occasional mortality from associated toxicities. Cytokine release syndrome (CRS) and Immune effector cell-associated neurotoxicity syndrome (ICANS) present barriers to the extensive use of CART cell therapy in the clinic. CRS can lead to fever, hypoxia, hypotension, coagulopathies, and multiorgan failure, and ICANS can result in cognitive dysfunction, seizures, and cerebral edema. The mechanisms of CRS and ICANS are becoming clearer, but many aspects remain unknown. Disease type and burden, peak serum CART cell levels, CART cell dose, CAR structure, elevated pro-inflammatory cytokines, and activated myeloid and endothelial cells all contribute to CART cell toxicity. Current guidelines for the management of toxicities associated with CART cell therapy vary between clinics, but are typically comprised of supportive care and treatment with corticosteroids or tocilizumab, depending on the severity of the symptoms. Acquiring a deeper understanding of CART cell toxicities and developing new management and prevention strategies are ongoing. In this review, we present findings in the mechanisms and management of CART cell toxicities.

CART Cell Toxicities: New Insight into Mechanisms and Management.

Chimeric antigen receptor T (CART)-cell immunotherapies have opened a door in the development of specialized gene therapies for hematological and solid cancers. Impressive response rates in pivotal trials led to the FDA approval of CART-cell therapy for certain hematological malignancies. However, autologous CART products are costly and time-intensive to manufacture, and most patients experience disease relapse within 1 year of CART administration. Additionally, CART-cell efficacy in solid tumors is extremely limited. CART-cell therapy is also associated with serious toxicities. Manufacturing difficulties, intrinsic T-cell defects, CART exhaustion, and treatment-associated toxicities are some of the current barriers to widespread adoption of CART-cell therapy. Genome editing tools such as CRISPR/Cas systems have demonstrated efficacy in further engineering CART cells to overcome these limitations. In this review, we will summarize the current approaches that use CRISPR to facilitate off-the-shelf CART products, increase CART-cell efficacy, and minimize CART-associated toxicities.

CRISPR Takes the Front Seat in CART-Cell Development.

Chimeric antigen receptor T (CART) cell immunotherapy has yielded significant clinical success in treating certain hematological malignancies. However, despite high initial response rates, most patients eventually relapse. Resistance to CART cell therapy can stem from tumor cell mutations, T cell defects, and tumor microenvironment (TME) immunosuppression. Tumor cells can downregulate target antigen expression to evade CART cell detection or mutate death receptor pathways to resist CART cell cytotoxicity. Patient T cells can be intrinsically defective, and CART cells often undergo exhaustion. The TME is abundant with immunosuppressive cells and factors which contribute to suboptimal CART cell activity. Collectively, issues originating in tumor cells, T cells, and the TME present significant hurdles to long-term remission after CART cell therapy. Various strategies to combat CART cell resistance have shown promise in preclinical studies and early clinical trials and are crucial to achieving durable responses.

Resistance to CART cell therapy: lessons learned from the treatment of hematological malignancies.

Chimeric antigen receptor T (CART) cells are a promising immunotherapy that has induced dramatic anti-tumor responses in certain B cell malignancies. However, CART cell expansion and trafficking are often insufficient to yield long-term remissions, and serious toxicities can arise after CART cell administration. Visualizing CART cell expansion and trafficking in patients can detect an inadequate CART cell response or serve as an early warning for toxicity development, allowing CART cell treatment to be tailored accordingly to maximize therapeutic benefits. To this end, various imaging platforms are being developed to track CART cells , including nonspecific strategies to image activated T cells and reporter systems to specifically detect engineered T cells. Many of these platforms are clinically applicable and hold promise to provide valuable information and guide improved CART cell treatment.

 CART cell imaging: Paving the way for success in CART cell therapy.

Although chimeric antigen receptor T (CART)-cell therapy has been successful in treating certain hematologic malignancies, wider adoption of CART-cell therapy is limited because of minimal activity in solid tumors and development of life-threatening toxicities, including cytokine release syndrome (CRS). There is a lack of a robust, clinically relevant imaging platform to monitor  expansion and trafficking to tumor sites. To address this, we utilized the sodium iodide symporter (NIS) as a platform to image and track CART cells. We engineered CD19-directed and B-cell maturation antigen (BCMA)-directed CART cells to express NIS (NISCART19 and NISBCMA-CART, respectively) and tested the sensitivity of F-TFB-PET to detect trafficking and expansion in systemic and localized tumor models and in a CART-cell toxicity model. NISCART19 and NISBCMA-CART cells were generated through dual transduction with two vectors and demonstrated exclusive I uptake . F-TFB-PET detected NISCART cells  to a sensitivity level of 40,000 cells. F-TFB-PET confirmed NISBCMA-CART-cell trafficking to the tumor sites in localized and systemic tumor models. In a xenograft model for CART-cell toxicity, F-TFB-PET revealed significant systemic uptake, correlating with CART-cell  expansion, cytokine production, and development of CRS-associated clinical symptoms. NIS provides a sensitive, clinically applicable platform for CART-cell imaging with PET scan. F-TFB-PET detected CART-cell trafficking to tumor sites and  expansion, correlating with the development of clinical and laboratory markers of CRS. These studies demonstrate a noninvasive, clinically relevant method to assess CART-cell functions .

Development of a Clinically Relevant Reporter for Chimeric Antigen Receptor T-cell Expansion, Trafficking, and Toxicity.

Pivotal clinical trials of B-cell maturation antigen (BCMA)-targeted chimeric antigen receptor (CAR) T-cell therapy in patients with relapsed/refractory multiple myeloma (MM) resulted in remarkable initial responses, which led to a recent FDA approval. Despite their success, durable remissions continue to be low, and the predominant mechanism of resistance is loss of CART-cells and inhibition by the tumor microenvironment (TME). MM is characterized by an immunosuppressive TME with an abundance of cancer-associated fibroblasts (CAFs). Using MM models, we studied the impact of CAFs on CART-cell efficacy and developed strategies to overcome CART-cell inhibition. We demonstrated that CAFs inhibit CART-cell anti-tumor activity and promote MM progression. CAFs express molecules such as fibroblast activation protein and SLAMF7, which are attractive immunotherapy targets. To overcome CAF-induced CART-cell inhibition, we generated CART cells targeting both MM cells and CAFs. Our dual-targeting CART-cell strategy significantly improved the effector functions of CART cells. We demonstrate for the first time that dual targeting both malignant plasma cells and the CAFs within the TME is a novel strategy to overcome resistance to CART-cell therapy in MM.

Targeting Cancer-Associated Fibroblasts in the Bone Marrow Prevents Resistance to CART-Cell Therapy in Multiple Myeloma.

Development of chimeric antigen receptor T (CART) cell therapy has led to unprecedented success against B cell leukemia and lymphoma and resulted in FDA-approved treatment protocols. Despite the initial clinical response in B cell-related malignancies, high relapse rates suggest that much work is needed to uncover mechanisms of resistance. In chronic lymphocytic leukemia (CLL), the durable activity of CAR T-cells is limited, and CART cell success is lower than in other malignancies. T cells from these patients are vulnerable to a state of dysfunction due to stresses including chronic infection, rapid cell cycle upon antigen recognition, immunosuppressive tumor microenvironment, and cancer-related treatments. T cells are also introduced to additional stresses when cultured ex vivo during the CART manufacturing process. All these factors contribute to the limited regenerative capacity of T cells, which can lead to CART treatment failure. In this short report, we will review the challenges of CAR T-cell therapy in patients with CLL and discuss potential strategies to overcome these challenges.

ArticleTotal : 2	Year
Publication title Cited by 8	2022
Publication title Cited by 4	2023

Article	Year
ERK Activation in CAR T Cells Is Amplified by CD28-Mediated Increase in CD3ζ Phosphorylation. iScience\| PubMed ID: 32325413	2020
Neurotoxicity and Cytokine Release Syndrome After Chimeric Antigen Receptor T Cell Therapy: Insights Into Mechanisms and Novel Therapies. Frontiers in immunology\| PubMed ID: 32983132	2020
A Concise Review of Neurologic Complications Associated with Chimeric Antigen Receptor T-cell Immunotherapy. Neurologic clinics\| PubMed ID: 33040871	2020
Leukemic extracellular vesicles induce chimeric antigen receptor T cell dysfunction in chronic lymphocytic leukemia. Molecular therapy : the journal of the American Society of Gene Therapy\| PubMed ID: 33388419	2021
CART Cell Toxicities: New Insight into Mechanisms and Management. Clinical hematology international\| PubMed ID: 33409484	2020
CRISPR Takes the Front Seat in CART-Cell Development. BioDrugs : clinical immunotherapeutics, biopharmaceuticals and gene therapy\| PubMed ID: 33638865	2021
Resistance to CART cell therapy: lessons learned from the treatment of hematological malignancies. Leukemia & lymphoma\| PubMed ID: 33682608	2021
CART cell imaging: Paving the way for success in CART cell therapy. Molecular therapy oncolytics\| PubMed ID: 33816781	2021
Development of a Clinically Relevant Reporter for Chimeric Antigen Receptor T-cell Expansion, Trafficking, and Toxicity. Cancer immunology research\| PubMed ID: 34244299	2021
Targeting Cancer-Associated Fibroblasts in the Bone Marrow Prevents Resistance to CART-Cell Therapy in Multiple Myeloma. Blood\| PubMed ID: 35090171	2022
Challenges of CAR T-cell Therapy in CLL: Lessons Learned. Experimental hematology\| PubMed ID: 35150777	2022

Elizabeth L. Siegler

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