The New Frontier and Mouse Models of Tumor Immunotherapy

 

• April 3, 2023

Decade of Myths about CAR-T Therapy

Recently, “CAR-T curative effect lasts for ten years” has been frequently searched in medical news! Professor Carl June, one of the CAR-T therapy experts, published an important paper on CAR-T therapy in the “Nature” magazine: the introduction of artificially synthesized CAR-T cells can be used in the periphery of leukemia patients who have survived for more than ten years without tumors. The blood is still detected, and these T cells are still active.

Notably, the scientists observed two distinct phases of the anti-leukemic response: an initial phase characterized by CD8+ CAR-T cells, followed by a proliferative CD4+ CAR-T cell population in subsequent years. The composition of these cells changed intriguingly over time in both patients. In the early stage of treatment, CAR-T cells are mainly CD8+ T cells. CD8 T cells are T cells that express CD8 glycoprotein as a T cell receptor on the cell membrane, which are often called killer T cells or cytotoxic T cells. But in the later stage, most CAR-T cells were converted to CD4+ T cells. CD4 T cells are T cells that express CD4 glycoprotein as a T cell receptor on the cell membrane, called helper T cells (TH cells). CD4 T cells and CD8 T cells are important members of cellular immunity.

The data show that: in the 1.4th year after Patient 1 received CAR-T cell therapy, the proportion of CD4 T cells in CAR-T cells reached 97.5%; in the 3.4th year, the ratio exceeded 99.6%; 7.2 years after treatment, the proportion of CD4 T cells reached 97.6%! This is a surprising discovery. There may be a close relationship between surface CD4 T cell subset proportion and long-term survival. This discovery will help scientists develop long-term effective CAR-T cell therapy.

Schematic diagram of changes in T cells in a patient over time [1]

The researchers noted that this change indicated the role of two types of cells at different stages of treatment: CD8 T cells, responsible for killing cancer cells, and CD4 T cells, responsible for long-term disease control. So long-term cancer control requires a combination of many different cell types. In addition, these results also once again proved that CAR-T cells could survive in the human body for a long time. In vitro responses such as sustained proliferation, cytokine expression, and metabolic activity indicated that these long-lived CAR-T cells remained functionally active. These findings provide new insights into the nature and function of long-term CAR-T cell signaling and persistence.

Schematic diagram of long-term onset of CAR-T therapy[1]

CAR-T cell therapy is an emerging cellular immunotherapy technology that has developed rapidly in recent years. It combines the high affinity of antigens and antibodies with the killing effect of T lymphocytes. By constructing a specific chimeric antigen receptor, T lymphocytes express this chimeric antigen receptor through gene transduction and finally recognize and kill target cells. This technique has already proven effective in blood cancers. Many CAR-T therapies have been approved worldwide, and many people have received treatment. As of April 2021, there are 2,073 active cell therapy drug development pipelines worldwide, an increase of 572 over the same period in 2020, a growth rate of 38%. CAR-T continues to occupy the bulk, followed by NK/NK-T therapy.

Global Oncology Therapy R&D Pipeline[2]

Classification of Tumor Immunotherapy

Tumor immunotherapy can be divided into active and passive immunotherapy.

• Active immunotherapy: stimulate and enhance host anti-tumor immune response. Active immunotherapy is divided into two types: specific and non-specific, the former uses tumor-specific antigens, and the latter uses substances that can non-specifically stimulate the immune system. Active immunotherapy is suitable for immune-responsive hosts and/or immunogenic tumors.
•  Passive immunotherapy: Treat tumors by infusing hosts with effector cells and/or antibody conjugates that can directly kill tumors. When the therapeutic agent is cells, it is called adoptive immunotherapy. Passive immunotherapy does not depend on the immune function status of the host.

Non-clinical Research Equipment for Cellular Immunotherapies

Medicilon has built a one-stop research platform for the preclinical R&D of cellular immunotherapies, covering a variety of immunotherapy methods including CAR-T, TCR-T and CAR-NK. Using a wealth of animal models and a variety of advanced analysis techniques, comprehensively considering the characteristics of different research projects, Medicilon has completed numerous pre-clinical projects for clients worldwide. Learn more.

A mouse model with Reconstituted Human Immune System

In order to understand the pathogenesis of tumors, tumor invasion, metastasis, and the relationship between tumors and hosts, it is necessary to establish appropriate animal models. Animal tumor models are important means and tools for studying the mechanism of tumor development. The study of mouse tumor models, especially various mouse models established using molecular biology, has been and will be one of the essential methods for tumor research in the future. Medicilon has a variety of humanized mouse tumor models that have been validated.

There are usually three methods for reconstituting the Humanized Immune System (HIS) in mice:

• Inject human peripheral blood mononuclear cells (PBMC) into immunodeficient mice for immune reconstruction, that is, the PBL-HIS model; this model can only rebuild human T cells, so it can only be used to evaluate T cell function drug.
• Inoculate human CD34+ hematopoietic stem cells into irradiated immunodeficient mice for immune reconstitution, that is, CD34+ HSC-HIS model; irradiation is conducive to the occupation of CD34 cells in mice.
• Transplant fetal thymus and fetal liver under the kidney capsule of irradiated immunodeficient mice and simultaneously inoculate human bone marrow hematopoietic stem cells for immune reconstruction, namely the BLT-HIS model. Although the reconstruction effect of this model is good, the source of materials is limited by ethics to a certain extent, and it is difficult to prepare in batches. It is suitable for scientific research, but it is not ideal for the large-scale, stable, and repeatable requirements required by drug research and development, so modeling barriers are relatively high.

Three ways of the establishment of immune reconstitution mouse model[3]

Tumor Immunology Drug Efficacy Model Evaluation Platform

Medicilon boasts nearly 300 tumor evaluation models. At the same time, we are empowering innovative therapies to comprehensively evaluate and study immuno-oncology. We have completed model establishment and efficacy evaluation of immuno-therapies such as CAR-T, TCR-T, CAR-NK, oncolytic virus, antibody (monoclonal antibody, double antibody, polyclonal antibody, etc.), siRNA, AAV.

PDX Models

Patient-Derived Tumor Xenograft Model (PDX): This model is established by directly transplanting the patient’s tumor tissue into immunodeficient mice. The characteristics of most primary tumors in histopathology, molecular biology and gene level, ensuring relatively reliable predictions of clinical efficacy. Therefore, the platform is widely used in the development of new drugs, especially in the selection of patients in clinical trials of target drugs and the study of predictive biomarkers.

Humanized Mouse Models

Humanized mice can easily simulate the biological characteristics of human beings, and They are very important for establishing preclinical pharmacodynamic evaluation models. They can provide suitable pharmacodynamic models for testing biotechnology drugs such as antibodies or antibody-drug conjugates (ADCs).

Syngeneic Mouse Models

The syngeneic mouse model tests the ability of model animals to fight cancer with their perfect immune system, as well as the therapeutic effects of immunotherapy. We can provide various syngeneic models to test the effectiveness of drugs according to our clients’ requirements. Typical orthotopic diseases include breast cancer, lung cancer, colon cancer, kidney cancer, diffuse large B-cell lymphoma (DLBCL), etc., with mice, rats and hamsters as test subjects.

Orthotopic Cancer Models

The orthotopic cancer model considers the interaction between tumor cells and their surrounding interstitial organ microenvironment and monitors tumor growth in drug efficacy evaluation. We can break down the barriers of experiment and technology with mature orthotopic transplantation models, including brain orthotopic transplantation, liver orthotopic transplantation, lung orthotopic transplantation, tibial bone marrow cavity orthotopic transplantation, and intravesical orthotopic transplantation.

Xenograft Models

We can provide various xenograft models to test the effectiveness of drugs according to our clients’ requirements. Typical diseases include head and neck cancer, lung cancer, breast cancer, gastric cancer and pancreatic cancer, with mice, rats and hamsters as test subjects. We are committed to providing clients with mature orthotopic models for evaluating the in vivo efficacy of ADC, completing the modeling and feeding of model animals in an AAALAC-accredited environment, and relevant pharmacodynamic evaluation experiments standards of a GLP level.

Reference:

[1] J Joseph Melenhorst, et al. Decade-long leukaemia remissions with persistence of CD4+ CAR T cells. Nature. 2022 Feb 2.

[2] Samik Upadhaya, et al. The clinical pipeline forcancer cell therapies. Nat RevDrug Discov.2021Jul;20(7):503-504.

[3] De La Rochere P, Guil-Luna S, Decaudin D, et al.Humanized mice for the study of immuno-oncology. Trends Immunol. 2018,39(9):748-763.

[4]. Nirali N Shah, et al. Long-Term Follow-Up of CD19-CAR T-Cell Therapy in Children and Young Adults With B-ALL. J Clin Oncol. 2021 May 20;39(15):1650-1659.

[5]. Elise A Chong, et al. Five-Year Outcomes forRefractory B-Cell Lymphomas with CAR T-Cell Therapy. N Engl JMed. 2021 Feb18;384(7):673-674.

[6]. Zhenguang Wang, et al.  Phase I study of CAR-T cells with PD-1 and TCR disruption in mesothelin-positive solid tumors. Cell Mol Immunol. 2021 Sep;18(9):2188-2198.