Advances in T-cell therapy for ALL

State-of-the-art knowledge on the regulation of advanced therapy medicinal products

Advanced therapy medicinal products (ATMPs) constitute therapeutic agents based on obtained cells, tissues or genes representing a novel treatment opportunity in medicine. In addition, ATMPs are administered into the cells or tissues of humans from the patient's own cells, donors, or genetically modified cells. Recently, the field of developing ATMPs has become a point of attention due to the clinical efficacy expected in defeating incurable diseases such as cancers and neurodegenerative disorders. Currently, there are two modes regarding the distribution of ATMPs. First, ATMPs that might be legally authorized for marketing. Second, the patients are able to access unapproved ATMPs through the hospital exemption (HE) or clinical practice program or through the compassionate use and expanded access program. The aim of this review is to discuss state-of-the-art knowledge on the regulation of ATMPs and provide regulatory recommendations.

CD19 Chimeric Antigen Receptor-Exosome Targets CD19 Positive B-lineage Acute Lymphocytic Leukemia and Induces Cytotoxicity

Simple Summary

Our research describes our designer exosomes express CD19 Chimeric Antigen Receptor (Exo-CD19 CAR). This novel Exo-CD19 CAR is cytotoxic for CD19-positive leukemia B-cells without interfering with cytotoxicity in CD19-negative cells. This innovation can be translated into broader clinical applications as CD19 CAR exosome-based nano-immunotherapy for B-cell leukemia instead of whole CD19 CAR T-cell immunotherapy.

Abstract

CAR-T cell therapy is not without some clinical adverse effects, namely cytokine storms, due to a massive release of cytokines when CAR-T cells multiply in the body. Our goal was to develop exosomes expressing CD19 CAR to treat CD19-positive B-cell malignancies, instead of using whole CD19 CAR-T cells, thereby reducing the clinical risk of uncontrolled cytokine storms. Exosomes are extracellular nanovesicles (30–150 nm), composed of lipids, proteins, and nucleic acids, that carry the fingerprint of their parent cells. Exosomes are a preferred delivery system in nano-immunotherapy. Here, HEK293T parent cells were transduced with CD19 CAR plasmids and cellular CD19 CAR expression was confirmed. Exosomes (Exo-CD19 CAR) were isolated from the conditioned medium of non-transduced (WT) and CD19 CAR plasmid transduced HEK293T cells. Consequently, CD19 B-lineage leukemia cell lines were co-cultured with Exo-CD19 CAR and cell death was measured. Our data show that Exo-CD19 CAR treatment induced cytotoxicity and elevated pro-apoptotic genes in CD19-positive leukemia B-cells without inducing cell death in CD19-negative cells. Overall, the novel CD19 CAR exosomes target the CD19 surface antigens of leukemic B-cells and can induce contact-dependent cytotoxicity.

Chimeric Antigen Receptor-modified T Cells Repressed Solid Tumors and Their Relapse in an Established Patient-derived Colon Carcinoma Xenograft Model

Adoptive transfer of T cells engineered with a chimeric antigen receptor (CAR) is deemed as the silver bullet to overcome the barriers of solid tumor treatment; however, the therapeutic application against solid tumors faces major challenges largely owing to the complex heterogeneity and immunosuppressive microenvironment of solid tumors. Preclinical development of CAR-T-cell products necessitates an appropriate animal model for the evaluation and improvement of their therapeutic capacities. Patient-derived xenograft (PDX) resembles real patients in several ways, and may serve as an attractive alternative to generate and evaluate the efficacy of CAR-T-cell products. In this study, we established and characterized a PDX mouse model implanted with colorectal cancer (CRC) xenograft. Human epidermal growth factor receptor 2 (HER2) expression in CRC specimens was detected by immunohistochemistry. The fragments of patient tumors were subcutaneously implanted into immunodeficient NOD-NPG mice after surgery. Furthermore, HER2-specific CAR-T cells were engineered and tested in our model to show their effectiveness in tumor clearance. Adoptive transfer of HER2-specific CAR-T cells resulted in the regression or even elimination of CRC xenograft and protection of relapse from rechallenged colon cancer tissue in PDX model. Significant survival advantage was achieved in these mice as compared with those transplanted with green fluorescent protein-T cells. Thus, this study showed that CAR-T-cell treatment may be a promising approach for solid tumor clearance and that the PDX model may be useful to evaluate the effects of CAR-T cells.

What is the Role of Hematopoietic Cell Transplantation (HCT) for Pediatric Acute Lymphoblastic Leukemia (ALL) in the Age of Chimeric Antigen Receptor T-Cell (CART) Therapy?

CD19 chimeric antigen receptor T-cell (CART) therapy has revolutionized the treatment of patients with relapsed/refractory hematologic malignancies, especially B-cell acute lymphoblastic leukemia. As CART immunotherapy expands from clinical trials to FDA-approved treatments, a consensus among oncologists and hematopoietic cell transplant (HCT) physicians is needed to identify which patients may benefit from consolidative HCT post-CART therapy. Here, we review CD19 CART therapy and the outcomes of published clinical trials, highlighting the use of post-CART HCT and the pattern of relapse after CD19 CART. At this time, the limited available long-term data from clinical trials precludes us from making definitive HCT recommendations. However, based on currently available data, we propose that consolidative HCT post-CART therapy be considered for all HCT-eligible patients and especially for pediatric patients with KMT2A-rearranged B-cell acute lymphoblastic leukemia.

Histone Deacetylases (HDACs) Guided Novel Therapies for T-cell lymphomas

T-cell lymphomas are a heterogeneous group of cancers with different pathogenesis and poor prognosis. Histone deacetylases (HDACs) are epigenetic modifiers that modulate many key biological processes. In recent years, HDACs have been fully investigated for their roles and potential as drug targets in T-cell lymphomas. In this review, we have deciphered the modes of action of HDACs, HDAC inhibitors as single agents, and HDACs guided combination therapies in T-cell lymphomas. The overview of HDACs on the stage of T-cell lymphomas, and HDACs guided therapies both as single agents and combination regimens endow great opportunities for the cure of T-cell lymphomas.

A novel antibody-TCR (AbTCR) platform combines Fab-based antigen recognition with gamma/delta-TCR signaling to facilitate T-cell cytotoxicity with low cytokine release

The clinical use of genetically modified T-cell therapies has led to unprecedented response rates in leukemia and lymphoma patients treated with anti-CD19 chimeric antigen receptor (CAR)-T. Despite this clinical success, FDA-approved T-cell therapies are currently limited to B-cell malignancies, and challenges remain with managing cytokine-related toxicities. We have designed a novel antibody-T-cell receptor (AbTCR) platform where we combined the Fab domain of an antibody with the γ and δ chains of the TCR as the effector domain. We demonstrate the ability of anti-CD19-AbTCR-T cells to trigger antigen-specific cytokine production, degranulation, and killing of CD19-positive cancer cells in vitro and in xenograft mouse models. By using the same anti-CD19 binding moiety on an AbTCR compared to a CAR platform, we demonstrate that AbTCR activates cytotoxic T-cell responses with a similar dose-response as CD28/CD3ζ CAR, yet does so with less cytokine release and results in T cells with a less exhausted phenotype. Moreover, in comparative studies with the clinically validated CD137 (4-1BB)-based CAR, CTL019, our anti-CD19-AbTCR shows less cytokine release and comparable tumor inhibition in a patient-derived xenograft leukemia model.

Artificial T Cell Mimetics to Combat Melanoma Tumor Growth

Despite recent breakthroughs in melanoma treatment with anti-PD-1 immunotherapy, innovative approaches are needed to improve off-target effects. In this study, we report a T cell mimetic microparticle delivery of soluble PD1 aiming at providing a carrier substrate for future combinatorial and targeting efforts. Microparticles of sizes varying from (5 μm to-7 μm) were conjugated with soluble mouse or human PD-1 through nearly irreversible binding between streptavidin and biotin. PD-1 conjugated microparticles (PDMPs) suppressed 3-dimensional tumor growth of human A375 and mouse B16-F10 melanoma cells compared to control microparticles conjugated with the Fc portion of human IgG1 (IgG1MPs). This can be attributed to competitive inhibition by PDMPs on a melanoma cell-intrinsic PD-1/PD-L1 pathway. A single, local administration of mPDMPs in a B16-F10 mouse melanoma model inhibited tumor growth significantly compared to control IgMPs at the same dose. CD45+ immune cells were found to infiltrate tumors treated with mPDMPs as a mechanism for tumor control. These results collectively suggest that PDMPs can target the melanoma cell-intrinsic PD-1/PD-L1 pathway and that these artificial T cell mimetics can be the scaffold for further improvements in anti-tumor immunotherapy.

Cancer Immunotherapy: An Evidence-Based Overview and Implications for Practice

BACKGROUND

Significant research progress has been made in immunotherapies since the mid-1990s, and this rapid evolution necessitates evidence-based education on immunotherapies, their pathophysiology, and their toxicities to provide safe, effective care.
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OBJECTIVES

The aim of this article is to provide an evidence-based overview, with implications for practice, of checkpoint inhibitors, monoclonal antibodies, oncolytic viral therapies, and chimeric antigen receptor T-cell therapies.
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METHODS

Each immunotherapy category is presented according to the pathophysiology of its immune modulation, the classes of agents within each category, evidence-based toxicities associated with each class, and implications for practice.
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FINDINGS

Immunotherapies vary in their pathophysiology and offer potential to be highly effective for the management of a wide array of cancer types. Understanding the unique pathophysiology and toxicities is necessary to assess, manage, and provide safe, effective patient-focused care.

Cytokine Release Syndrome: Inpatient Care for Side Effects of CAR T-Cell Therapy

BACKGROUND

Pediatric patients with relapsed and refractory acute lymphoblastic leukemia are more often being treated with chimeric antigen receptor (CAR) T-cell therapy. As with any new therapy, the management of this patient population has a unique set of challenges. The side effects of this therapy can range from mild to severe, with cytokine release syndrome being the most common reason for hospitalization.
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OBJECTIVES

This article presents common side effects, treatments, and challenges of caring for hospitalized patients who have received CAR T-cell therapy.
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METHODS

A case study is used to illustrate a patient's inpatient hospitalization course after receiving CAR T-cell therapy, including the management of treatment-related toxicities.
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FINDINGS

As treatments emerge, nurses will be challenged with learning the associated side effects and toxicities. CAR T-cell therapy can result in a unique trajectory of potential symptoms and the potential for complete resolution of disease.

Recent advances and novel treatment paradigms in acute lymphocytic leukemia

This is an exciting time in the treatment of acute lymphoblastic leukemia (ALL) given the advances in the relapsed/refractory setting. The development of antibody treatments (including antibody drug conjugates with toxins) offers a different treatment approach compared with conventional chemotherapy regimens. Moreover, the use of bispecific T-cell-engager antibodies (BiTEs) such as blinatumomab harness the cytotoxic activity of T cells against CD19-positive lymphoblasts. Another strategy involves the use of chimeric antigen receptor (CAR) T cells. CAR T cells have demonstrated promising results in the relapsed/refractory setting. However, the use of BiTEs and CAR T cells is also associated with a distinct set of adverse reactions that must be taken into account by the treating physician. Apart from the above strategies, the use of other targeted therapies has attracted interest. Namely, the discovery of the Philadelphia (Ph)-like signature in children and young adults with ALL has led to the use of tyrosine kinase inhibitors (TKI) in these patients. The different drugs and strategies that are being tested in the relapsed/refractory ALL setting pose a unique challenge in identifying the optimum sequence of treatment and determining which approaches should be considered for frontline treatment.

Immunotherapeutic implications of IL-6 blockade for cytokine storm

IL-6 contributes to host defense against infections and tissue injuries. However, exaggerated, excessive synthesis of IL-6 while fighting environmental stress leads to an acute severe systemic inflammatory response known as ‘cytokine storm’, since high levels of IL-6 can activate the coagulation pathway and vascular endothelial cells but inhibit myocardial function. Remarkable beneficial effects of IL-6 blockade therapy using a humanized anti-IL-6 receptor antibody, tocilizumab were recently observed in patients with cytokine release syndrome complicated by T-cell engaged therapy. In this review we propose the possibility that IL-6 blockade may constitute a novel therapeutic strategy for other types of cytokine storm, such as the systemic inflammatory response syndrome including sepsis, macrophage activation syndrome and hemophagocytic lymphohistiocytosis.

From Immunodeficiency to Humanization: The Contribution of Mouse Models to Explore HTLV-1 Leukemogenesis

The first discovered human retrovirus, Human T-Lymphotropic Virus type 1 (HTLV-1), is responsible for an aggressive form of T cell leukemia/lymphoma. Mouse models recapitulating the leukemogenesis process have been helpful for understanding the mechanisms underlying the pathogenesis of this retroviral-induced disease. This review will focus on the recent advances in the generation of immunodeficient and human hemato-lymphoid system mice with a particular emphasis on the development of mouse models for HTLV-1-mediated pathogenesis, their present limitations and the challenges yet to be addressed.

CD19-redirected chimeric antigen receptor-modified T cells: a promising immunotherapy for children and adults with B-cell acute lymphoblastic leukemia (ALL)

Relapsed and chemotherapy-refractory B-cell acute lymphoblastic leukemia (B-ALL) remain significant causes of cancer-associated morbidity and mortality for children and adults. Development of new molecularly targeted treatment strategies for patients with high-risk B-ALL is thus a major preclinical and clinical priority. Adoptive cellular therapy with patient-derived human T cells genetically engineered to express CD19 redirected chimeric antigen receptors (CD19 CAR T cells) is one immunotherapeutic modality that has recently demonstrated remarkable efficacy in re-inducing remission in patients with multiply relapsed B-ALL. Investigative teams at several major cancer centers are currently conducting phase I clinical trials in children and/or adults with relapsed/refractory B-ALL to assess the safety and to identify the maximally tolerated dose of each group's CD19 CAR T-cell product. All groups have reported major clinical toxicities associated with CD19 CAR T-cell treatment, including cytokine release syndrome (CRS) and macrophage activation syndrome, neurologic dysfunction and aplasia of normal B lymphocytes, while CD19 CAR T cells persist in vivo. Toxicities have generally been transient or manageable with supportive care measures. Some patients with life-threatening CD19 CAR T-cell induced sequelae have received anti-cytokine receptor antibody treatment to diminish CRS symptoms and/or corticosteroids to terminate CAR T-cell proliferation. Remarkably, 67-90% of children and adults with B-ALL treated with CD19 CAR T cells in these trials have achieved morphologic leukemia remission with many patients also in molecular remission. The duration of CD19 CAR T cell persistence in vivo has varied appreciably among treated patients and likely reflects differences in the CD19 CAR constructs utilized at each institution. CD19-positive and CD19-negative B-ALL relapses after CD19 CAR T-cell treatment have occurred in some patients. Phase II trials to assess the efficacy of CD19 CAR T-cell immunotherapy in larger cohorts of patients with relapsed/refractory B-ALL are ongoing or planned.