T-cell Immunotherapies and the Role of Nonclinical Assessment: The Balance between Efficacy and Pathology

ATMP Environmental Exposure Assessment in European Healthcare Settings: A Systematic Review of the Literature

Since 2007, a new class of biologic products for human use called "advanced therapy medicinal products (ATMP)" have been legally integrated in the European Medical Agency. They consist of recombinant nucleic acid, engineered cells, cells, or tissues. In the United States, ATMP fall under the regulatory framework of biological products and the term "cell and gene therapy product" is used in the legislative and regulatory documents. Potential clinical applications are broad, particularly, in the field of cancer, inherited genetic disease, and regenerative medicine. Indeed, the benefit conferred by CD19 chimeric antigen receptor T cells led to the first engineered cell therapy products to be approved by the Food and Drug Administration (FDA) in 2017. Gene therapy products to treat orphan diseases are also extensively developed with many clinical trials ongoing in the world. Nevertheless, the use of these therapeutic products is complex and requires careful considerations in the terms of regulatory and hospital setting requirements, such as storage, handling, administration, and disposal which justify the implementation of a secured medication circuit. Through this systematic review of the literature, the authors wanted to compile data on the assessment of environmental exposure related to the use of ATMP in healthcare setting to secure their medication circuit. A literature search was conducted on PubMed and Web of Science, and 32 publications dealing with environmental exposure assessment and ATMP were selected. In addition, marketed ATMPs were identified and data regarding the environmental concerns were extracted from product information sections from European Public Assessment Reports (EPAR). The environmental contamination assessments were mainly addressed in the reviews rather than in original articles related to the use of ATMP. Most of the product information sections from EPAR suggested precautions rather than requirements when dealing with environmental consideration following ATMP handling. Nevertheless, these precautions usually remain elusive especially concerning waste disposal and the detection of biological material on the work surfaces, and mainly relate to the genetically modified organisms (GMO) over non-GMO cellular products. Pharmaceutical oversight and adherence to the good preparation practices and good clinical practices are essential to ensure the safe use in term of environmental concern of these new therapeutic products in healthcare setting.

Nonclinical safety assessment of engineered T cell therapies

Over the last decade, immunotherapy has established itself as an important novel approach in the treatment of cancer, resulting in a growing importance in oncology. Engineered T cell therapies, namely chimeric antigen receptor (CAR) T cells and T cell receptor (TCR) T cell therapies, are platform technologies that have enabled the development of products with remarkable efficacy in several hematological malignancies and are thus the focus of intense research and development activity. While engineered T cell therapies offer promise in addressing currently intractable cancers, they also present unique challenges, including their nonclinical safety assessment. A workshop organized by HESI and the US Food and Drug Administration (FDA) was held to provide an interdisciplinary forum for representatives of industry, academia and regulatory authorities to share information and debate on current practices for the nonclinical safety evaluation of engineered T cell therapies. This manuscript leverages what was discussed at this workshop to provide an overview of the current important nonclinical safety assessment considerations for the development of these therapeutic modalities (cytokine release syndrome, neurotoxicity, on-target/off-tumor toxicities, off-target effects, gene editing or vector integration-associated genomic injury). The manuscript also discusses approaches used for hazard identification or risk assessment and provides a regulatory perspective on such aspects.

Regulating innovation in the early development of cell therapies

Clinical need for paradigm shifts in efficacy and safety is driving the rapid and wide-ranging innovation in cell therapies for cancer beyond existing regulatory frameworks. Critical issues emerging during clinical trials frequently reflect unresolved elements of the regulation of innovation conundrum from earlier stages of development. We address this challenge using a global regulators’ perspective on the preclinical development of cell therapies, as a navigational aid to intended commercial use which maximises the clinical relevance of developmental data. We examine the implications of tumour targeting based on B cell, natural killer cell, conventional and unconventional T cell receptor domains; multiplex approaches; genetic manipulation strategies; and autologous versus allogeneic cell sources. We propose that detailed characterisation of both the cell source and final product is critical to optimising manufacture of individualised autologous or off the shelf allogeneic cell therapies, enabling product consistency to underpin extrapolation of clinical trial data to the expected commercial use. We highlight preclinical approaches to characterising target antigens including the Human Cell Atlas initiative, multi-dimensional cell culture, and safety testing against activated, proliferating or stressed control cells. Practical solutions are provided for preclinical toxicity studies when cell therapies target uniquely human tumour antigens, including illustrative mitigation measures for potential toxicity likely to support timely approval of first-in-human clinical trials. We recommend addressing the regulation of innovation conundrum through serial engagement between innovators and regulators early in the development of cell therapies for cancer, accelerating patient access while safeguarding against unacceptable toxicities.

Externally-Controlled Systems for Immunotherapy: From Bench to Bedside

Immunotherapy is a very promising therapeutic approach against cancer that is particularly effective when combined with gene therapy. Immuno-gene therapy approaches have led to the approval of four advanced therapy medicinal products (ATMPs) for the treatment of p53-deficient tumors (Gendicine and Imlygic), refractory acute lymphoblastic leukemia (Kymriah) and large B-cell lymphomas (Yescarta). In spite of these remarkable successes, immunotherapy is still associated with severe side effects for CD19+ malignancies and is inefficient for solid tumors. Controlling transgene expression through an externally administered inductor is envisioned as a potent strategy to improve safety and efficacy of immunotherapy. The aim is to develop smart immunogene therapy-based-ATMPs, which can be controlled by the addition of innocuous drugs or agents, allowing the clinicians to manage the intensity and durability of the therapy. In the present manuscript, we will review the different inducible, versatile and externally controlled gene delivery systems that have been developed and their applications to the field of immunotherapy. We will highlight the advantages and disadvantages of each system and their potential applications in clinics.

Targeting Cancer Stem Cells by Genetically Engineered Chimeric Antigen Receptor T Cells

The term cancer stem cell (CSC) starts 25 years ago with the evidence that CSC is a subpopulation of tumor cells that have renewal ability and can differentiate into several distinct linages. Therefore, CSCs play crucial role in the initiation and the maintenance of cancer. Moreover, it has been proposed throughout several studies that CSCs are behind the failure of the conventional chemo-/radiotherapy as well as cancer recurrence due to their ability to resist the therapy and their ability to re-regenerate. Thus, the need for targeted therapy to eliminate CSCs is crucial; for that reason, chimeric antigen receptor (CAR) T cells has currently been in use with high rate of success in leukemia and, to some degree, in patients with solid tumors. This review outlines the most common CSC populations and their common markers, in particular CD133, CD90, EpCAM, CD44, ALDH, and EGFRVIII, the interaction between CSCs and the immune system, CAR T cell genetic engineering and signaling, CAR T cells in targeting CSCs, and the barriers in using CAR T cells as immunotherapy to treat solid cancers.

Current Perspectives in Cancer Immunotherapy

Different immunotherapeutic approaches have proved to be of significant clinical value to many patients with different types of advanced cancer. However, we need more precise immunotherapies and predictive biomarkers to increase the successful response rates. The advent of next generation sequencing technologies and their applications in immuno-oncology has helped us tremendously towards this aim. We are now moving towards the realization of personalized medicine, thus, significantly increasing our expectations for a more successful management of the disease. Here, we discuss the current immunotherapeutic approaches against cancer, including immune checkpoint blockade with an emphasis on anti-PD-L1 and anti-CTLA-4 monoclonal antibodies. We also analyze a growing list of other co-inhibitory and co-stimulatory markers and emphasize the mechanism of action of the principal pathway for each of these, as well as on drugs that either have been FDA-approved or are under clinical investigation. We further discuss recent advances in other immunotherapies, including cytokine therapy, adoptive cell transfer therapy and therapeutic vaccines. We finally discuss the modulation of gut microbiota composition and response to immunotherapy, as well as how tumor-intrinsic factors and immunological processes influence the mutational and epigenetic landscape of progressing tumors and response to immunotherapy but also how immunotherapeutic intervention influences the landscape of cancer neoepitopes and tumor immunoediting.

Chimeric antigen receptor T-cell toxicity

PURPOSE OF REVIEW

Chimeric antigen receptor -(CAR) T-cell therapy has become a commonly used immunotherapy originally used in the treatment of B-cell leukemias but which are now applied broadly across tumor classes. Although high rates of remission are associated with CAR T-cell therapy, toxicities associated with these novel treatment regimens can be lethal if not recognized in a timely manner.

RECENT FINDINGS

Cytokine release syndrome and neurotoxicity are the two most common toxicities associated with CAR T-cell therapy. Cytokine release syndrome is characterized by a flu-like illness accompanied by significant hemodynamic instability; treatments include administration of tocilizumab and corticosteroids. Neurotoxicity is associated with nonpattern-specific neurological changes and can rapidly progress to a comatose state from cerebral edema and death. Other potential toxicities from CAR T-cell therapy include tumor lysis syndrome, B-cell aplasia, graft versus host disease, and dermatological eruptions.

SUMMARY

Clinical awareness of CAR T-cell toxicities is important because prompt treatment leads to improved survival and remission rates.

Cytokine release syndrome. Reviewing a new entity in the intensive care unit

Immunotherapy seeks to harness the power of the immune system to eradicate malignant tissues. Despite impressive therapeutic success, however, it can be accompanied by severe adverse effects such as cytokine release syndrome (CRS). These therapies cause the release of a great amount of cytokines, with IL-6 playing a central role, that can potentially lead to multiple organ dysfunction. The diagnosis is based on the presence of compatible clinical symptoms, elevated biomarkers and recent treatment with a biological agent. Mild cases can be managed through symptomatic treatment and fluids, while more severe episodes may need supportive therapy and specific care with the anti-IL-6 receptor monoclonal antibody tocilizumab. Although corticosteroids are also effective, they suppress T-cell activity, and so should only be considered as second line therapy or in cases of severe neurological involvement, since tocilizumab does not cross the blood-brain barrier. Cytokine release syndrome generally has a good prognosis, often being reversible and with a good response to specific treatment. Despite possible concerns about the admission of such patients (mainly with advanced oncological disease), we consider that the Intensive Care Unit should remain an option, since these individuals present a potentially reversible drug-related adverse event and are being treated with a new drug that could change the prognosis of the disorder. Intensive care medicine will become a key component in the management of the complications of modern cancer therapies, dealing with patients presenting an overactive immune system producing organ dysfunction while also trying to maintain treatment efficacy. This is the new paradigm.