Tumor localization of adoptively transferred indium-111 labeled tumor infiltrating lymphocytes in patients with metastatic melanoma

Advances in Radionuclide-Labeled Biological Carriers for Tumor Imaging and Treatment

Biological carriers have emerged as significant tools to deliver radionuclides in nuclear medicine, providing a meaningful perspective for tumor imaging and treatment. Various radionuclide-labeled biological carriers have been developed to meet the needs of biomedical applications. This review introduces the principles of radionuclide-mediated imaging and therapy and the selected criteria of them, as well as a comprehensive description of the characteristics and functions of representative biological carriers including bacteria, cells, viruses, and their biological derivatives, emphasizing the labeled strategies of biological carriers combined with radionuclides. Subsequently, we in-depth introduce the application of radionuclide-labeled biological carriers in tumor imaging and treatment, including the imaging of the behaviors of biological carriers in vivo and tumor metastasis and the tumor treatment by radionuclide therapy, plus other strategies and radiation-induced photodynamic therapy. Finally, the challenges and prospects of radionuclide-labeled biological carriers are discussed to improve the shortcomings of this innovative platform and promote clinical transformation in the field of medical imaging.

CAR T-cells for pediatric solid tumors: where to go from here?

Despite the great success that chimeric antigen receptor (CAR) T-cells have had in patients with B-cell malignancies and multiple myeloma, they continue to have limited efficacy against most solid tumors. Especially in the pediatric population, pre- and post-treatment biopsies are rarely performed due to ethical reasons, and thus, our understanding is still very limited regarding the mechanisms in the tumor microenvironment by which tumor cells exclude effectors and attract immune-suppressive cells. Nevertheless, based on the principles that are known, current T-cell engineering has leveraged some of these processes and created more potent CAR T-cells. The recent discovery of new oncofetal antigens and progress made in CAR design have expanded the potential pool of candidate antigens for therapeutic development. The most promising approaches to enhance CAR T-cells are novel CAR gating strategies, creative ways of cytokine delivery to the TME without enhancing systemic toxicity, and hijacking the chemokine axis of tumors for migratory purposes. With these new modifications, the next step in the era of CAR T-cell development will be the clinical validation of these promising preclinical findings.

Nanofibrous MultiDomain Peptide Hydrogels Provide T Cells a 3D, Cytocompatible Environment for Cell Expansion and Antigen-Specific Killing

T cells have the ability to recognize and kill specific target cells, giving therapies based on their potential for treating infection, diabetes, cancer, and other diseases. However, the advancement of T cell-based treatments has been hindered by difficulties in their ex vivo activation and expansion, the number of cells required for sustained in vivo levels, and preferential localization following systemic delivery. Biomaterials may help to overcome many of these challenges by providing a combined means of proliferation, antigen presentation, and cell localization upon delivery. In this work, we studied self-assembling Multidomain Peptides (MDPs) as scaffolds for T cell culture, activation, and expansion. We evaluated the effect of different MDP chemistries on their biocompatibility with T cells and the maintenance of antigen specificity for T cells cultured in the hydrogels. We also examined the potential application of MDPs as scaffolds for T cell activation and expansion and the effect of MDP encapsulation on T cell phenotype. We found high cell viability when T cells were encapsulated in noncationic MDPs, O5 and D2, and superior retention of antigen specificity and tumor-reactivity were preserved in the anionic MDP, D2. Maintenance of antigen recognition by T cells in D2 hydrogels was confirmed by quantifying immune synapses of T Cells engaged with antigen-presenting cancer cells. When 3D cultured in anionic MDP D2 coloaded with anti-CD3, anti-CD28, IL2, IL7, and IL15, we observed successful T cell proliferation evidenced by upregulation of CD27 and CD107a. This study is the first to investigate the potential of self-assembling peptide-based hydrogels as 3D scaffolds for human T cell applications and demonstrates that MDP hydrogels are a viable platform for enabling T cell in vitro activation, expansion, and maintenance of antigen specificity and therefore a promising tool for future T cell-based therapies.

Tumor-Infiltrating Lymphocyte and Other Cell Therapies for Metastatic Melanoma

ABSTRACT

Major progress in prolonging survival of patients with advanced melanoma has been made in the past decade because of the development and approval of immune checkpoint inhibitor and targeted therapies. However, for nonresponding or relapsing patients, their prognosis is still dismal. Based on clinical trial data, treatment with adoptive cell therapies holds great promise. In patients with metastatic melanoma progressing on or nonresponsive to single-agent anti-programmed cell death 1, infusion of tumor-infiltrating lymphocytes can produce responses in up to half of patients, with durable complete responses in up to 20%. Genetic modification of peripheral blood T cells with T-cell receptors derived from tumor-specific T cells, or with chimeric antigen receptors, has the potential to further improve treatment outcomes in this refractory population. In this review, we will discuss the historical development, current status, and future perspectives of adoptive T-cell therapies in melanoma.

Combined use of NK cells and radiotherapy in the treatment of solid tumors

Natural killer (NK) cells are innate lymphocytes possessing potent tumor surveillance and elimination activity. Increasing attention is being focused on the role of NK cells in integral antitumor strategies (especially immunotherapy). Of note, therapeutic efficacy is considerable dependent on two parameters: the infiltration and cytotoxicity of NK cells in tumor microenvironment (TME), both of which are impaired by several obstacles (e.g., chemokines, hypoxia). Strategies to overcome such barriers are needed. Radiotherapy is a conventional modality employed to cure solid tumors. Recent studies suggest that radiotherapy not only damages tumor cells directly, but also enhances tumor recognition by immune cells through altering molecular expression of tumor or immune cells via the in situ or abscopal effect. Thus, radiotherapy may rebuild a NK cells-favored TME, and thus provide a cost-effective approach to improve the infiltration of NK cells into solid tumors, as well as elevate immune-activity. Moreover, the radioresistance of tumor always hampers the response to radiotherapy. Noteworthy, the puissant cytotoxic activity of NK cells not only kills tumor cells directly, but also increases the response of tumors to radiation via activating several radiosensitization pathways. Herein, we review the mechanisms by which NK cells and radiotherapy mutually promote their killing function against solid malignancies. We also discuss potential strategies harnessing such features in combined anticancer care.

CAR T cell therapy for patients with solid tumours: key lessons to learn and unlearn

Chimeric antigen receptor (CAR) T cells have been approved for use in patients with B cell malignancies or relapsed and/or refractory multiple myeloma, yet efficacy against most solid tumours remains elusive. The limited imaging and biopsy data from clinical trials in this setting continues to hinder understanding, necessitating a reliance on imperfect preclinical models. In this Perspective, I re-evaluate current data and suggest potential pathways towards greater success, drawing lessons from the few successful trials testing CAR T cells in patients with solid tumours and the clinical experience with tumour-infiltrating lymphocytes. The most promising approaches include the use of pluripotent stem cells, co-targeting multiple mechanisms of immune evasion, employing multiple co-stimulatory domains, and CAR ligand-targeting vaccines. An alternative strategy focused on administering multiple doses of short-lived CAR T cells in an attempt to pre-empt exhaustion and maintain a functional effector pool should also be considered.

Two cases of severe pulmonary toxicity from highly active mesothelin-directed CAR T cells

Multiple clinical studies have treated mesothelin (MSLN)-positive solid tumors by administering MSLN-directed chimeric antigen receptor (CAR) T cells. Although these products are generally safe, efficacy is limited. Therefore, we generated and characterized a potent, fully human anti-MSLN CAR. In a phase 1 dose-escalation study of patients with solid tumors, we observed two cases of severe pulmonary toxicity following intravenous infusion of this product in the high-dose cohort (1-3 × 108 T cells per m2). Both patients demonstrated progressive hypoxemia within 48 h of infusion with clinical and laboratory findings consistent with cytokine release syndrome. One patient ultimately progressed to grade 5 respiratory failure. An autopsy revealed acute lung injury, extensive T cell infiltration, and accumulation of CAR T cells in the lungs. RNA and protein detection techniques confirmed low levels of MSLN expression by benign pulmonary epithelial cells in affected lung and lung samples obtained from other inflammatory or fibrotic conditions, indicating that pulmonary pneumocyte and not pleural expression of mesothelin may lead to dose-limiting toxicity. We suggest patient enrollment criteria and dosing regimens of MSLN-directed therapies consider the possibility of dynamic expression of mesothelin in benign lung with a special concern for patients with underlying inflammatory or fibrotic conditions.

Magnetic Particle Imaging in Vascular Imaging, Immunotherapy, Cell Tracking, and Noninvasive Diagnosis

Magnetic particle imaging (MPI) is a new tracer-based imaging modality that is useful in diagnosing various pathophysiology related to the vascular system and for sensitive tracking of cytotherapies. MPI uses nonradioactive and easily assimilated nanometer-sized iron oxide particles as tracers. MPI images the nonlinear Langevin behavior of the iron oxide particles and has allowed for the sensitive detection of iron oxide-labeled therapeutic cells in the body. This review will provide an overview of MPI technology, the tracer, and its use in vascular imaging and cytotherapies using molecular targets.

In Vivo Cellular Magnetic Imaging: Labeled vs. Unlabeled Cells

Superparamagnetic iron oxide (SPIO)-labeling of cells has been applied for magnetic resonance imaging (MRI) cell tracking for over 30 years, having resulted in a dozen or so clinical trials. SPIO nanoparticles are biodegradable and can be broken down into elemental iron, and hence the tolerance of cells to magnetic labeling has been overall high. Over the years, however, single reports have accumulated demonstrating that the proliferation, migration, adhesion and differentiation of magnetically labeled cells may differ from unlabeled cells, with inhibition of chondrocytic differentiation of labeled human mesenchymal stem cells (hMSCs) as a notable example. This historical perspective provides an overview of some of the drawbacks that can be encountered with magnetic labeling. Now that magnetic particle imaging (MPI) cell tracking is emerging as a new in vivo cellular imaging modality, there has been a renaissance in the formulation of SPIO nanoparticles this time optimized for MPI. Lessons learned from the occasional past pitfalls encountered with SPIO-labeling of cells for MRI may expedite possible future clinical translation of (combined) MRI/MPI cell tracking.

Clinical Pharmacology Perspectives for Adoptive Cell Therapies in Oncology

Adoptive cell therapies (ACTs) have shown transformative efficacy in oncology with five US Food and Drug Administration (FDA) approvals for chimeric antigen receptor (CAR) T-cell therapies in hematological malignancies, and promising activity for T cell receptor T-cell therapies in both liquid and solid tumors. Clinical pharmacology can play a pivotal role in optimizing ACTs, aided by modeling and simulation toolboxes and deep understanding of the underlying biological and immunological processes. Close collaboration and multilevel data integration across functions, including chemistry, manufacturing, and control, biomarkers, bioanalytical, and clinical science and safety teams will be critical to ACT development. As ACT is comprised of alive, polyfunctional, and heterogeneous immune cells, its overall physicochemical and pharmacological property is vastly different from other platforms/modalities, such as small molecule and protein therapeutics. In this review, we first describe the unique kinetics of T cells and the appropriate bioanalytical strategies to characterize cellular kinetics. We then assess the distinct aspects of clinical pharmacology for ACTs in comparison to traditional small molecule and protein therapeutics. Additionally, we provide a review for the five FDA-approved CAR T-cell therapies and summarize their properties, cellular kinetic characteristics, dose-exposure-response relationship, and potential baseline factors/variables in product, patient, and regimen that may affect the safety and efficacy. Finally, we probe into existing empirical and mechanistic quantitative techniques to understand how various modeling and simulation approaches can support clinical pharmacology strategy and propose key considerations to be incorporated and explored in future models.

Superkine IL-2 and IL-33 Armored CAR T Cells Reshape the Tumor Microenvironment and Reduce Growth of Multiple Solid Tumors

Chimeric-antigen receptor (CAR) T-cell therapy has shown remarkable efficacy against hematologic tumors. Yet, CAR T-cell therapy has had little success against solid tumors due to obstacles presented by the tumor microenvironment (TME) of these cancers. Here, we show that CAR T cells armored with the engineered IL-2 superkine Super2 and IL-33 were able to promote tumor control as a single-agent therapy. IFNγ and perforin were dispensable for the effects of Super2- and IL-33-armored CAR T cells. Super2 and IL-33 synergized to shift leukocyte proportions in the TME and to recruit and activate a broad repertoire of endogenous innate and adaptive immune cells including tumor-specific T cells. However, depletion of CD8+ T cells or NK cells did not disrupt tumor control, suggesting that broad immune activation compensated for loss of individual cell subsets. Thus, we have shown that Super2 and IL-33 CAR T cells can promote antitumor immunity in multiple solid tumor models and can potentially overcome antigen loss, highlighting the potential of this universal CAR T-cell platform for the treatment of solid tumors.

Untangling the Knots of Regulatory T Cell Therapy in Solid Organ Transplantation

Numerous preclinical studies have provided solid evidence supporting adoptive transfer of regulatory T cells (Tregs) to induce organ tolerance. As a result, there are 7 currently active Treg cell-based clinical trials in solid organ transplantation worldwide, all of which are early phase I or phase I/II trials. Although the results of these trials are optimistic and support both safety and feasibility, many experimental and clinical unanswered questions are slowing the progression of this new therapeutic alternative. In this review, we bring to the forefront the major challenges that Treg cell transplant investigators are currently facing, including the phenotypic and functional diversity of Treg cells, lineage stability, non-standardized ex vivo Treg cell manufacturing process, adequacy of administration route, inability of monitoring and tracking infused cells, and lack of biomarkers or validated surrogate endpoints of efficacy in clinical trials. With this plethora of interrogation marks, we are at a challenging and exciting crossroad where properly addressing these questions will determine the successful implementation of Treg cell-based immunotherapy in clinical transplantation.

M. de Rosales R. Direct Cell Radiolabeling for in Vivo Cell Tracking with PET and SPECT Imaging

The arrival of cell-based therapies is a revolution in medicine. However, its safe clinical application in a rational manner depends on reliable, clinically applicable methods for determining the fate and trafficking of therapeutic cells in vivo using medical imaging techniques─known as in vivo cell tracking. Radionuclide imaging using single photon emission computed tomography (SPECT) or positron emission tomography (PET) has several advantages over other imaging modalities for cell tracking because of its high sensitivity (requiring low amounts of probe per cell for imaging) and whole-body quantitative imaging capability using clinically available scanners. For cell tracking with radionuclides, ex vivo direct cell radiolabeling, that is, radiolabeling cells before their administration, is the simplest and most robust method, allowing labeling of any cell type without the need for genetic modification. This Review covers the development and application of direct cell radiolabeling probes utilizing a variety of chemical approaches: organic and inorganic/coordination (radio)chemistry, nanomaterials, and biochemistry. We describe the key early developments and the most recent advances in the field, identifying advantages and disadvantages of the different approaches and informing future development and choice of methods for clinical and preclinical application.

Innovative Strategies to Improve the Clinical Application of NK Cell-Based Immunotherapy

Natural killer cells constitute a part of the innate immune system that mediates an effective immune response towards virus-infected and malignant cells. In recent years, research has focused on exploring and advancing NK cells as an active immunotherapy platform. Despite major advances, there are several key challenges that need to be addressed for the effective translation of NK cell research to clinical applications. This review highlights some of these challenges and the innovative strategies being developed to overcome them, including in vitro expansion, in vivo persistence, infiltration to the tumor site, and prevention of exhaustion.

Injectable Diels-Alder cycloaddition hydrogels with tuneable gelation, stiffness and degradation for the sustained release of T-lymphocytes

Engineered T-cell therapies have proven highly efficacious for the treatment of haematological cancers, but translation of this success to solid tumours has been limited, in part, due to difficulties in maintaining high doses at specific target sites. Hydrogel delivery systems that provide a sustained release of T-cells at the target site are emerging as a promising strategy. Therefore, in this study we aimed to develop an injectable hydrogel that gels in situ via efficient Diels-Alder cycloaddition (DAC) chemistry and provides a sustained release of T-cells through gradual hydrolysis of the hydrogel matrix. Hydrogels were prepared via the DAC between fulvene and maleimide functionalised poly(ethylene glycol) (PEG) derivatives. By adjusting the concentration and molecular weight of the functionalised PEGs in the hydrogel formulation the in vitro gelation time (T_gel), initial Young's modulus (E) and degradation time (T_d) could be tailored from 15-150 min, 5-179 kPa and 7-114 h, respectively. Prior to gelation, the formulations could be readily injected through narrow gauge (26 G) needles with the working time correlating closely with the T_gel. A 5 wt% hydrogel formation with conjugated cyclic RGD motif was found to be optimal for the encapsulation and release of CD3⁺ T-cells with a near linear release profile and >70% cell viability over the first 4 d and release continuing out to 7 d. With their tuneable T_gel, T_d and stiffness, the DAC hydrogels provide the opportunity to control the release period and profile of encapsulated cells.

Whole-Body Imaging to Assess Cell-Based Immunotherapy: Preclinical Studies with an Update on Clinical Translation

In the past decades, immunotherapies against cancers made impressive progress. Immunotherapy includes a broad range of interventions that can be separated into two major groups: cell-based immunotherapies, such as adoptive T cell therapies and stem cell therapies, and immunomodulatory molecular therapies such as checkpoint inhibitors and cytokine therapies. Genetic engineering techniques that transduce T cells with a cancer-antigen-specific T cell receptor or chimeric antigen receptor have expanded to other cell types, and further modulation of the cells to enhance cancer targeting properties has been explored. Because cell-based immunotherapies rely on cells migrating to target organs or tissues, there is a growing interest in imaging technologies that non-invasively monitor transferred cells in vivo. Here, we review whole-body imaging methods to assess cell-based immunotherapy using a variety of examples. Following a review of preclinically used cell tracking technologies, we consider the status of their clinical translation.

Promise and challenges of clinical non-invasive T-cell tracking in the era of cancer immunotherapy

In the last decades, our understanding of the role of the immune system in cancer has significantly improved and led to the discovery of new immunotherapeutic targets and tools, which boosted the advances in cancer immunotherapy to fight a growing number of malignancies. Approved immunotherapeutic approaches are currently mainly based on immune checkpoint inhibitors, antibody-derived targeted therapies, or cell-based immunotherapies. In essence, these therapies induce or enhance the infiltration and function of tumor-reactive T cells within the tumors, ideally resulting in complete tumor eradication. While the clinical application of immunotherapies has shown great promise, these therapies are often accompanied either by a variety of side effects as well as partial or complete unresponsiveness of a number of patients. Since different stages of disease progression elicit different local and systemic immune responses, the ability to longitudinally interrogate the migration and expansion of immune cells, especially T cells, throughout the whole body might greatly facilitate disease characterization and understanding. Furthermore, it can serve as a tool to guide development as well as selection of appropriate treatment regiments. This review provides an overview about a variety of immune-imaging tools available to characterize and study T-cell responses induced by anti-cancer immunotherapy. Moreover, challenges are discussed that must be taken into account and overcome to use immune-imaging tools as predictive and surrogate markers to enhance assessment and successful application of immunotherapies.

Non-invasive cell-tracking methods for adoptive T cell therapies

Adoptive T cell therapies (ACT) have demonstrated groundbreaking results in blood cancers and melanoma. Nevertheless, their significant cost, the occurrence of severe adverse events, and their poor performance in solid tumors are important hurdles hampering more widespread applicability. In vivo cell tracking allows instantaneous and non-invasive monitoring of the distribution, tumor homing, persistence, and redistribution to other organs of infused T cells in patients. Furthermore, cell tracking could aid in the clinical management of patients, allowing the detection of non-responders or severe adverse events at an early stage. This review provides a concise overview of the main principles and potential of cell tracking, followed by a discussion of the clinically relevant labeling strategies and their application in ACT.

Imaging CAR T-cell kinetics in solid tumors: Translational implications

Success in solid tumor chimeric antigen receptor (CAR) T-cell therapy requires overcoming several barriers, including lung sequestration, inefficient accumulation within the tumor, and target-antigen heterogeneity. Understanding CAR T-cell kinetics can assist in the interpretation of therapy response and limitations and thereby facilitate developing successful strategies to treat solid tumors. As T-cell therapy response varies across metastatic sites, the assessment of CAR T-cell kinetics by peripheral blood analysis or a single-site tumor biopsy is inadequate for interpretation of therapy response. The use of tumor imaging alone has also proven to be insufficient to interpret response to therapy. To address these limitations, we conducted dual tumor and T-cell imaging by use of a bioluminescent reporter and positron emission tomography in clinically relevant mouse models of pleural mesothelioma and non-small cell lung cancer. We observed that the mode of delivery of T cells (systemic versus regional), T-cell activation status (presence or absence of antigen-expressing tumor), and tumor-antigen expression heterogeneity influence T-cell kinetics. The observations from our study underscore the need to identify and develop a T-cell reporter—in addition to standard parameters of tumor imaging and antitumor efficacy—that can be used for repeat imaging without compromising the efficacy of CAR T cells in vivo.

Extensive functional comparisons between chimeric antigen receptors and T cell receptors highlight fundamental similarities

Though TCRs have been subject to limited engineering in the context of therapeutic design and optimization, they are used largely as found in nature. On the other hand, CARs are artificial, composed of different segments of proteins that function in the immune system. This characteristic raises the possibility of altered response to immune regulatory stimuli. Here we describe a large-scale, systematic comparison of CARs and TCRs across 5 different pMHC targets, with a total of 19 constructs examined in vitro. These functional measurements include CAR- and TCR-mediated activation, proliferation, and cytotoxicity in both acute and chronic settings. Surprisingly, we find no consistent difference between CARs and TCRs as receptor classes with respect to their relative sensitivity to major regulators of T cell activation: PD-L1, CD80/86 and IL-2. Though TCRs often emerge from human blood directly as potent, selective receptors, CARs must be heavily optimized to attain these properties for pMHC targets. Nonetheless, when iteratively improved and compared head to head in functional tests, CARs appear remarkably similar to TCRs with respect to immune modulation.

Engineering enhanced CAR T-cells for improved cancer therapy

Chimeric antigen receptor (CAR) T-cell therapies have evolved from a research tool to a paradigm-shifting therapy with impressive responses in B cell malignancies. This review summarizes the current state of the CAR T-cell field, focusing on CD19- and B cell maturation antigen-directed CAR T-cells, the most developed of the CAR T-cell therapies. We discuss the many challenges to CAR-T therapeutic success and innovations in CAR design and T-cell engineering aimed at extending this therapeutic platform beyond hematologic malignancies.

Immersion in the search for effective cancer immunotherapies

Real innovations in medicine and science are historic and singular; the stories behind each occurrence are precious. At Molecular Medicine we have established the Anthony Cerami Award in Translational Medicine to document and preserve these histories. The monographs recount the seminal events as told in the voice of the original investigators who provided the crucial early insight. These essays capture the essence of discovery, chronicling the birth of ideas that created new fields of research and launched trajectories that persisted and ultimately influenced how disease is prevented, diagnosed, and treated. In this volume, the Cerami Award Monograph is by Steven A. Rosenberg, Chief of Surgery at the National Cancer Institute in Bethesda, Maryland, USA. A pioneer in the development of immunotherapies and gene therapies for advanced cancers, this is the story of Dr. Rosenberg’s scientific journey.

Randomized phase II trial of lymphodepletion plus adoptive cell transfer of tumor-infiltrating lymphocytes, with or without dendritic cell vaccination, in patients with metastatic melanoma

BACKGROUND

The adoptive transfer of tumor-infiltrating lymphocytes (TIL) has demonstrated robust efficacy in metastatic melanoma patients. Tumor antigen-loaded dendritic cells (DCs) are believed to optimally activate antigen-specific T lymphocytes. We hypothesized that the combined transfer of TIL, containing a melanoma antigen recognized by T cells 1 (MART-1) specific population, with MART-1-pulsed DC will result in enhanced proliferation and prolonged survival of transferred MART-1 specific T cells in vivo ultimately leading to improved clinical responses.

DESIGN

We tested the combination of TIL and DC in a phase II clinical trial of patients with advanced stage IV melanoma. HLA-A0201 patients whose early TIL cultures demonstrated reactivity to MART-1 peptide were randomly assigned to receive TIL alone or TIL +DC pulsed with MART-1 peptide. The primary endpoint was to evaluate the persistence of MART-1 TIL in the two arms. Secondary endpoints were to evaluate clinical response and survival.

RESULTS

Ten patients were given TIL alone while eight patients received TIL+DC vaccine. Infused MART-1 reactive CD8⁺ TIL were tracked in the blood over time by flow cytometry and results show good persistence in both arms, with no difference in the persistence of MART-1 between the two arms. The objective response rate was 30% (3/10) in the TIL arm and 50% (4/8) in the TIL+DC arm. All treatments were well tolerated.

CONCLUSIONS

The combination of TIL +DC showed no difference in the persistence of MART-1 TIL compared with TIL therapy alone. Although more patients showed a clinical response to TIL+DC therapy, this study was not powered to resolve differences between groups.

TRIAL REGISTRATION NUMBER

NCT00338377.

Imaging of T-cell Responses in the Context of Cancer Immunotherapy

Immunotherapy, which promotes the induction of cytotoxic T lymphocytes and enhances their infiltration into and function within tumors, is a rapidly expanding and evolving approach to treating cancer. However, many of the critical denominators for inducing effective anticancer immune responses remain unknown. Efforts are underway to develop comprehensive ex vivo assessments of the immune landscape of patients prior to and during response to immunotherapy. An important complementary approach to these efforts involves the development of noninvasive imaging approaches to detect immune targets, assess delivery of immune-based therapeutics, and evaluate responses to immunotherapy. Herein, we review the merits and limitations of various noninvasive imaging modalities (MRI, PET, and single-photon emission tomography) and discuss candidate targets for cellular and molecular imaging for visualization of T-cell responses at various stages along the cancer-immunity cycle in the context of immunotherapy. We also discuss the potential use of these imaging strategies in monitoring treatment responses and predicting prognosis for patients treated with immunotherapy.

Systemic Delivery of Oncolytic Adenovirus to Tumors Using Tumor-Infiltrating Lymphocytes as Carriers

Immunotherapy with tumor-infiltrating lymphocytes (TIL) or oncolytic adenoviruses, have shown promising results in cancer treatment, when used as separate therapies. When used in combination, the antitumor effect is synergistically potentiated due oncolytic adenovirus infection and its immune stimulating effects on T cells. Indeed, studies in hamsters have shown a 100% complete response rate when animals were treated with oncolytic adenovirus coding for TNFa and IL-2 (Ad5/3-E2F-D24-hTNFa-IRES-hIL2; TILT-123) and TIL therapy. In humans, one caveat with oncolytic virus therapy is that intratumoral injection has been traditionally preferred over systemic administration, for achieving sufficient virus concentrations in tumors, especially when neutralizing antibodies emerge. We have previously shown that 5/3 chimeric oncolytic adenovirus can bind to human lymphocytes for avoidance of neutralization. In this study, we hypothesized that incubation of oncolytic adenovirus (TILT-123) with TILs prior to systemic injection would allow delivery of virus to tumors. This approach would deliver both components in one self-amplifying product. TILs would help deliver TILT-123, whose replication will recruit more TILs and increase their cytotoxicity. In vitro, TILT-123 was seen binding efficiently to lymphocytes, supporting the idea of dual administration. We show in vivo in different models that virus could be delivered to tumors with TILs as carriers.

Semiflexible Immunobrushes Induce Enhanced T Cell Activation and Expansion

A variety of bioactive materials developed to expand T cells for adoptive transfer into cancer patients are currently evaluated in the clinic. In most cases, T cell activating biomolecules are attached to rigid surfaces or matrices and form a static interface between materials and the signaling receptors on the T cells. We hypothesized that a T cell activating polymer brush interface might better mimic the cell surface of a natural antigen-presenting cell, facilitating receptor movement and concomitant advantageous mechanical forces to provide enhanced T cell activating capacities. Here, as a proof of concept, we synthesized semiflexible polyisocyanopeptide (PIC) polymer-based immunobrushes equipped with T cell activating agonistic anti-CD3 (αCD3) and αCD28 antibodies placed on magnetic microbeads. We demonstrated enhanced efficiency of ex vivo expansion of activated primary human T cells even at very low numbers of stimulating antibodies compared to rigid beads. Importantly, the immunobrush architecture appeared crucial for this improved T cell activating capacity. Immunobrushes outperform current benchmarks by producing higher numbers of T cells exhibiting a combination of beneficial phenotypic characteristics, such as reduced exhaustion marker expression, high cytokine production, and robust expression of cytotoxic hallmarks. This study indicates that semiflexible immunobrushes have great potential in making T cell-based immunotherapies more effective.

Cancer therapy in mice using a pure population of CD8+ T cell specific to the AH1 tumor rejection antigen

There is a growing interest in the use of patient-derived T cells for the treatment of various types of malignancies. The expansion of a polyclonal and polyspecific population of tumor-reactive T cells, with a subsequent infusion into the same donor patient, has been implemented, sometimes with positive results. It is not known, however, whether a set of T cells with a single antigen specificity may be sufficient for an effective therapy. To gain more insights in this matter, we used naturally occurring T cells recognizing a retroviral peptide (AH1), which is endogenous in many tumor cell lines of BALB/c origin and which serves as potent tumor rejection antigen. We were able to isolate and expand this rare population of T cells to numbers suitable for therapy experiments in mice (i.e., up to 30 × 10⁶ cells/mouse). After the expansion process, T cells efficiently killed antigen-positive tumor cells in vitro and demonstrated tumor growth inhibition in two syngeneic murine models of cancer. However, AH1-specific T cells failed to induce complete regressions of established tumors. The incomplete activity was associated with a failure of injected T cells to survive in vivo, as only a very limited amount of T cells was found in tumor or secondary lymphoid organs 72 h after injection. These data suggest that future therapeutic strategies based on autologous T cells may require the potentiation of tumor-homing and survival properties of cancer-specific T cells.

Chemokine networks modulating natural killer cell trafficking to solid tumors

Natural killer (NK) cell-based cell therapy has been emerging as a powerful weapon in the treatment of multiple malignancies. However, the inadequate infiltration of the therapeutic NK cells into solid tumors remains a big challenge to their clinical utility. Chemokine networks, which play essential roles in the migration of lymphocytes, have been recognized as critical in driving the intratumoral infiltration of NK cells via interactions between soluble chemokines and their receptors. Often, such interactions are complex and disease-specific. In the context of NK cells, chemokine receptors of note have included CCR2, CCR5, CCR7, CXCR3, and CX3CR1. The immunobiology of chemokine-receptor interactions has fueled the development of approaches that hope to improve the infiltration of NK cells into the microenvironment of solid tumors. Stimulation of NK cells ex vivo in the presence of various cytokines (such as IL-2, IL-15, and IL-21) and genetic engineering of NK cells have been utilized to alter the chemokine receptor profile and generate NK cells with higher infiltrating capacity. Additionally, the immune-suppressive tumor microenvironment has also been targeted, by introducing, either directly or indirectly, chemokine ligands which NK cells are able to respond to, ultimately creating a more hospitable niche for NK cell trafficking. Such strategies have promoted the infiltration and activity of infused NK cells into multiple solid tumors. In this review, we discuss how chemokine receptors and their ligands coordinate and how they can be manipulated to regulate the trafficking, distribution, and residence of NK cells in solid tumors.

Cancer T-cell therapy: building the foundation for a cure

T-cell cancer therapy is a clinical field flush with opportunity.  It is part of the revolution in immuno-oncology, most apparent in the dramatic clinical success of PD-1/CTLA-4 antibodies and chimeric antigen receptor T-cells (CAR-Ts) to cure certain melanomas and lymphomas, respectively.  Therapeutics based on T cells ultimately hold more promise because of their capacity to carry out complex behaviors and their ease of modification via genetic engineering.  But to overcome the substantial obstacles of effective solid-tumor treatment, T-cell therapy must access novel molecular targets or exploit existing ones in new ways.  As always, tumor selectivity is the key. T-cell therapy has the potential to address target opportunities afforded by its own unique capacity for signal integration and high sensitivity.  With a history of breathtaking innovation, the scientific foundation for the cellular modality has often been bypassed in favor of rapid advance in the clinic.  This situation is changing, as the mechanistic basis for activity of CAR-Ts and TCR-Ts is backfilled by painstaking, systematic experiments—harking back to last century’s evolution and maturation of the small-molecule drug discovery field.   We believe this trend must continue for T-cell therapy to reach its enormous potential.  We support an approach that integrates sound reductionist scientific principles with well-informed, thorough preclinical and translational clinical experiments.

Imaging of cell-based therapy using 89Zr-oxine ex vivo cell labeling for positron emission tomography

With the rapid development of anti-cancer cell-based therapies, such as adoptive T cell therapies using tumor-infiltrating T cells, T cell receptor transduced T cells, and chimeric antigen receptor T cells, there has been a growing interest in imaging technologies to non-invasively track transferred cells in vivo. Cell tracking using ex vivo cell labeling with positron emitting radioisotopes for positron emission tomography (PET) imaging has potential advantages over single-photon emitting radioisotopes. These advantages include intrinsically higher resolution, higher sensitivity, and higher signal-to-background ratios. Here, we review the current status of recently developed Zirconium-89 (89Zr)-oxine ex vivo cell labeling with PET imaging focusing on its applications and future perspectives. Labeling of cells with 89Zr-oxine is completed in a series of relatively simple steps, and its low radioactivity doses required for imaging does not interfere with the proliferation or function of the labeled immune cells. Preclinical studies have revealed that 89Zr-oxine PET allows high-resolution in vivo tracking of labeled cells for 1-2 weeks after cell transfer both in mice and non-human primates. These results provide a strong rationale for the clinical translation of 89Zr-oxine PET-based imaging of cell-based therapy.

CAR Chase: Where Do Engineered Cells Go in Humans?

Chimeric antigen receptor (CAR) - and T-cell receptor (TCR) - modified T-cells are rapidly emerging as a viable treatment option for cancer patients. While initial clinical trials for these CAR T cells showed response rates of over 90% in some cases, retrospective studies have revealed a wide variability in patient responses as well as a significant proportion of patients relapsing after an initial response. In addition, patients often have severe adverse reactions to this therapy (e.g., cytokine release and neurologic syndromes). As a result, much research is still needed to be able to predict both therapeutic outcomes and possible toxicities. Furthermore, little success has been seen in treating solid tumors with engineered T cells and uncovering modes of failure is a topic of much research. Finally, little is known about the T cells' pharmacokinetics after infusion into the patient, as standard methods of tracking the cells analyze peripheral blood and tumor biopsies - both of which lack spatiotemporal information. Herein, we propose that reporter gene-based imaging of engineered T cells in humans would be tremendously valuable in elucidating the fate of the transplanted T cells and would greatly facilitate clinical translation of new CAR and TCR technologies. Currently, there are no FDA-approved reporter genes and few methods have advanced to human studies. Herein, we outline current reporter gene approaches to track engineered cells in vivo, analyze why current reporter genes have not progressed into the clinic, and propose "rules" for designing a widely applicable reporter gene for use in humans.

Induced pluripotent stem cell-derived natural killer cells gene-modified to express chimeric antigen receptor-targeting solid tumors

The use of allogeneic, pluripotent stem cell-derived immune cells for cancer immunotherapy has been the subject of recent research, including clinical trials. The use of pluripotent stem cells as the source for allogeneic immune cells facilitates stringent quality control of the final product, regarding efficacy, safety, and producibility. In this review, we have described the characteristics of natural killer (NK) cells from multiple cell sources, including pluripotent stem cells, the chimeric antigen receptor (CAR)-modification method and strategy for these NK cells, and the current and planned clinical trials of CAR-modified induced pluripotent stem cell-derived NK cells.

Persistent Polyfunctional Chimeric Antigen Receptor T Cells That Target Glypican 3 Eliminate Orthotopic Hepatocellular Carcinomas in Mice

BACKGROUND AND AIMS

Glypican 3 (GPC3) is an oncofetal antigen involved in Wnt-dependent cell proliferation that is highly expressed in hepatocellular carcinoma (HCC). We investigated whether the functions of chimeric antigen receptors (CARs) that target GPC3 are affected by their antibody-binding properties.

METHODS

We collected peripheral blood mononuclear cells from healthy donors and patients with HCC and used them to create CAR T cells, based on the humanized YP7 (hYP7) and HN3 antibodies, which have high affinities for the C-lobe and N-lobe of GPC3, respectively. NOD/SCID/IL-2Rgcnull (NSG) mice were given intraperitoneal injections of luciferase-expressing (Luc) Hep3B or HepG2 cells and after xenograft tumors formed, mice were given injections of saline or untransduced T cells (mock control), or CAR (HN3) T cells or CAR (hYP7) T cells. In other NOD/SCID/IL-2Rgcnull (NSG) mice, HepG2-Luc or Hep3B-Luc cells were injected into liver, and after orthotopic tumors formed, mice were given 1 injection of CAR (hYP7) T cells or CD19 CAR T cells (control). We developed droplet digital polymerase chain reaction and genome sequencing methods to analyze persistent CAR T cells in mice.

RESULTS

Injections of CAR (hYP7) T cells eliminated tumors in 66% of mice by week 3, whereas CAR (HN3) T cells did not reduce tumor burden. Mice given CAR (hYP7) T cells remained tumor free after re-challenge with additional Hep3B cells. The CAR T cells induced perforin- and granzyme-mediated apoptosis and reduced levels of active β-catenin in HCC cells. Mice injected with CAR (hYP7) T cells had persistent expansion of T cells and subsets of polyfunctional CAR T cells via antigen-induced selection. These T cells were observed in the tumor microenvironment and spleen for up to 7 weeks after CAR T-cell administration. Integration sites in pre-infusion CAR (HN3) and CAR (hYP7) T cells were randomly distributed, whereas integration into NUPL1 was detected in 3.9% of CAR (hYP7) T cells 5 weeks after injection into tumor-bearing mice and 18.1% of CAR (hYP7) T cells at week 7. There was no common site of integration in CAR (HN3) or CD19 CAR T cells from tumor-bearing mice.

CONCLUSIONS

In mice with xenograft or orthoptic liver tumors, CAR (hYP7) T cells eliminate GPC3-positive HCC cells, possibly by inducing perforin- and granzyme-mediated apoptosis or reducing Wnt signaling in tumor cells. GPC3-targeted CAR T cells might be developed for treatment of patients with HCC.

How Non-invasive in vivo Cell Tracking Supports the Development and Translation of Cancer Immunotherapies

Immunotherapy is a relatively new treatment regimen for cancer, and it is based on the modulation of the immune system to battle cancer. Immunotherapies can be classified as either molecular or cell-based immunotherapies, and both types have demonstrated promising results in a growing number of cancers. Indeed, several immunotherapies representing both classes are already approved for clinical use in oncology. While spectacular treatment successes have been reported, particularly for so-called immune checkpoint inhibitors and certain cell-based immunotherapies, they have also been accompanied by a variety of severe, sometimes life-threatening side effects. Furthermore, not all patients respond to immunotherapy. Hence, there is the need for more research to render these promising therapeutics more efficacious, more widely applicable, and safer to use. Whole-body in vivo imaging technologies that can interrogate cancers and/or immunotherapies are highly beneficial tools for immunotherapy development and translation to the clinic. In this review, we explain how in vivo imaging can aid the development of molecular and cell-based anti-cancer immunotherapies. We describe the principles of imaging host T-cells and adoptively transferred therapeutic T-cells as well as the value of traceable cancer cell models in immunotherapy development. Our emphasis is on in vivo cell tracking methodology, including important aspects and caveats specific to immunotherapies. We discuss a variety of associated experimental design aspects including parameters such as cell type, observation times/intervals, and detection sensitivity. The focus is on non-invasive 3D cell tracking on the whole-body level including aspects relevant for both preclinical experimentation and clinical translatability of the underlying methodologies.

Feasibility of real-time in vivo 89Zr-DFO-labeled CAR T-cell trafficking using PET imaging

Introduction

Chimeric antigen receptor (CAR) T-cells have been recently developed and are producing impressive outcomes in patients with hematologic malignancies. However, there is no standardized method for cell trafficking and in vivo CAR T-cell monitoring. We assessed the feasibility of real-time in vivo⁸⁹Zr-p-Isothiocyanatobenzyl-desferrioxamine (Df-Bz-NCS, DFO) labeled CAR T-cell trafficking using positron emission tomography (PET).

Results

The ⁸⁹Zr-DFO radiolabeling efficiency of Jurkat/CAR and human peripheral blood mononuclear cells (hPBMC)/CAR T-cells was 70%–79%, and cell radiolabeling activity was 98.1–103.6 kBq/10⁶ cells. Cell viability after radiolabeling was >95%. Cell proliferation was not significantly different during the early period after radiolabeling, compared with unlabeled cells; however, the proliferative capacity decreased over time (day 7 after labeling). IL-2 or IFN-γ secretion was not significantly different between unlabeled and labeled CAR T-cells. PET/magnetic resonance imaging in the xenograft model showed that most of the ⁸⁹Zr-DFO-labeled Jurkat/CAR T-cells were distributed in the lung (24.4% ± 3.4%ID) and liver (22.9% ± 5.6%ID) by one hour after injection. The cells gradually migrated from the lung to the liver and spleen by day 1, and remained stable in these sites until day 7 (on day 7: lung 3.9% ± 0.3%ID, liver 36.4% ± 2.7%ID, spleen 1.4% ± 0.3%ID). No significant accumulation of labeled cells was identified in tumors. A similar pattern was observed in ex vivo biodistributions on day 7 (lung 3.0% ± 1.0%ID, liver 19.8% ± 2.2%ID, spleen 2.3% ± 1.7%ID). ⁸⁹Zr-DFO-labeled hPBMC/CAR T-cells showed a similar distribution, compared with Jurkat/CAR T-cells, on serial PET images. CAR T cell distribution was cross-confirmed by flow cytometry, Alu polymerase chain reaction, and immunohistochemistry.

Conclusion

Real-time in vivo cell trafficking is feasible using PET imaging of ⁸⁹Zr-DFO-labeled CAR T-cells. This can be used to investigate cellular kinetics, initial in vivo biodistribution, and safety profiles in future CAR T-cell development.

Imaging of T-cells and their responses during anti-cancer immunotherapy

Immunotherapy has proven to be an effective approach in a growing number of cancers. Despite durable clinical responses achieved with antibodies targeting immune checkpoint molecules, many patients do not respond. The common denominator for immunotherapies that have successfully been introduced in the clinic is their potential to induce or enhance infiltration of cytotoxic T-cells into the tumour. However, in clinical research the molecules, cells and processes involved in effective responses during immunotherapy remain largely obscure. Therefore, in vivo imaging technologies that interrogate T-cell responses in patients represent a powerful tool to boost further development of immunotherapy. This review comprises a comprehensive analysis of the in vivo imaging technologies that allow the characterisation of T-cell responses induced by anti-cancer immunotherapy, with emphasis on technologies that are clinically available or have high translational potential. Throughout we discuss their respective strengths and weaknesses, providing arguments for selecting the optimal imaging options for future research and patient management.

Intra-arterial Versus Intravenous Adoptive Cell Therapy in a Mouse Tumor Model

Adoptive cell transfer therapy for cancer has existed for decades and is experiencing a resurgence in popularity that has been facilitated by improved methods of production, techniques for genetic modification, and host preconditioning. The trafficking of adoptively transferred lymphocytes and infiltration into the tumor microenvironment is sine qua non for successful tumor eradication; however, the paradox of extremely poor trafficking of lymphocytes into the tumor microenvironment raises the issue of how best to deliver these cells to optimize entry into tumor tissue. We examined the route of administration as a potential modifier of both trafficking and antitumor efficacy. Femoral artery cannulation and tail vein injection for the intra-arterial (IA) and IV delivery, respectively, were utilized in the B16-OVA/OT-I mouse model system. Both IV and IA infusions showed decreased tumor growth and prolonged survival. However, although significantly increased T-cell tumor infiltration was observed in IA mice, tumor growth and survival were not improved as compared with IV mice. These studies suggest that IA administration produces increased early lymphocyte trafficking, but a discernable survival benefit was not seen in the murine model examined.

Direct and antibody-dependent cell-mediated cytotoxicity of head and neck squamous cell carcinoma cells by high-affinity natural killer cells

High affinity natural killer cells (haNKs) are a cell therapy product capable of mediating both direct and antibody-dependent cell-mediated cytotoxicity (ADCC). These cells may be particularly useful in tumors that escape T-cell anti-tumor immunity by harboring antigen processing and presentation defects. Here, we demonstrated that haNKs directly kill both HPV-positive and negative head and neck squamous cell carcinoma cells. Variable tumor cell sensitivity to haNK direct cytotoxicity did not correlated with MHC class I chain-related protein A or B (MICA or MICB) expression. Importantly, haNK killing was significantly enhanced via ADCC mediated by cetuximab or avelumab in cells with higher baseline EGFR or PD-L1 expression, respectively. The ability of IFNγ to induce tumor cell PD-L1 expression correlated with enhanced PD-L1-specific ADCC. IFNγ induced neither tumor cell EGFR expression nor EGFR-specific ADCC. Although a single dose of 8 Gy IR did not appear to directly enhance susceptibility to haNK killing alone, enhanced PD-L1- and EGFR-mediated ADCC after IR correlated with increased PD-L1 and EGFR expression in one of four models. This pre-clinical evidence supports the investigation of haNK cellular therapy in combination with ADCC-mediating mAbs, with or without IR, in the clinical trial setting for patients with advanced HNSCCs. Given the MHC-unrestricted nature of this treatment, it may represent an opportunity to treat patients with non-T-cell inflamed tumors.

Synthetic T cell receptor-based lymphocytes for cancer therapy

Chimeric antigen receptor (CAR) T cells have been remarkably successful in patients with hematological malignancies expressing the CD19 surface antigen, but such level of success is far from being replicated in solid tumors. Engineered T cell receptor (TCR) T cells targeting cancer antigens were first developed over two decades ago and represent an alternative adoptive T cell approach that has produced provocative clinical data in solid cancers. However, several factors may hinder this technology from realizing its full potential, including the need for HLA matching, HLA downregulation by cancer cells, the suppressive tumor microenvironment, and tissue liabilities resulting from targeting antigens shared with normal tissues. Efforts therefore continue to engineer enhanced versions of CAR T and TCR T therapies that can overcome current barriers. Furthermore, emergent novel TCR-based, HLA-unrestricted platforms may also provide unique tools that integrate the complexity of the TCR signaling cascade that can be applied to treat solid tumors. This article reviews the current state of development of TCR T cell approaches and discusses next generation improvements to overcome their current limitations.

Injectable Biomimetic Hydrogels as Tools for Efficient T Cell Expansion and Delivery

Biomaterial-based scaffolds are promising tools for controlled immunomodulation. They can be applied as three dimensional (3D) culture systems in vitro, whereas in vivo they may be used to dictate cellular localization and exert spatiotemporal control over cues presented to the immune system. As such, scaffolds can be exploited to enhance the efficacy of cancer immunotherapies such as adoptive T cell transfer, in which localization and persistence of tumor-specific T cells dictates treatment outcome. Biomimetic polyisocyanopeptide (PIC) hydrogels are polymeric scaffolds with beneficial characteristics as they display reversible thermally-induced gelation at temperatures above 16°C, which allows for their minimally invasive delivery via injection. Moreover, incorporation of azide-terminated monomers introduces functional handles that can be exploited to include immune cell-modulating cues. Here, we explore the potential of synthetic PIC hydrogels to promote the in vitro expansion and in vivo local delivery of pre-activated T cells. We found that PIC hydrogels support the survival and vigorous expansion of pre-stimulated T cells in vitro even at high cell densities, highlighting their potential as 3D culture systems for efficient expansion of T cells for their adoptive transfer. In particular, the reversible thermo-sensitive behavior of the PIC scaffolds favors straightforward recovery of cells. PIC hydrogels that were injected subcutaneously gelated instantly in vivo, after which a confined 3D structure was formed that remained localized for at least 4 weeks. Importantly, we noticed no signs of inflammation, indicating that PIC hydrogels are non-immunogenic. Cells co-delivered with PIC polymers were encapsulated within the scaffold in vivo. Cells egressed gradually from the PIC gel and migrated into distant organs. This confirms that PIC hydrogels can be used to locally deliver cells within a supportive environment. These results demonstrate that PIC hydrogels are highly promising for both the in vitro expansion and in vivo delivery of pre-activated T cells. Covalent attachment of biomolecules onto azide-functionalized PIC polymers provides the opportunity to steer the phenotype, survival or functional response of the adoptively transferred cells. As such, PIC hydrogels can be used as valuable tools to improve current adoptive T cell therapy strategies.

Off-the-shelf cell therapy with induced pluripotent stem cell-derived natural killer cells

Cell therapy is emerging as a very promising therapeutic modality against cancer, spearheaded by the clinical success of chimeric antigen receptor (CAR) modified T cells for B cell malignancies. Currently, FDA-approved CAR-T cell products are based on engineering of autologous T cells harvested from the patient, typically using a central manufacturing facility for gene editing before the product can be delivered to the clinic and infused to the patients. For a broader implementation of advanced cell therapy and to reduce costs, it would be advantageous to use allogeneic "universal" cell therapy products that can be stored in cell banks and provided upon request, in a manner analogous to biopharmaceutical drug products. In this review, we outline a roadmap for development of off-the-shelf cell therapy based on natural killer (NK) cells derived from induced pluripotent stem cells (iPSCs). We discuss strategies to engineer iPSC-derived NK (iPSC-NK) cells for enhanced functional potential, persistence, and homing.

Chemokine Receptors and Exercise to Tackle the Inadequacy of T Cell Homing to the Tumor Site

While cancer immune therapy has revolutionized the treatment of metastatic disease across a wide range of cancer diagnoses, a major limiting factor remains with regard to relying on adequate homing of anti-tumor effector cells to the tumor site both prior to and after therapy. Adoptive cell transfer (ACT) of autologous T cells have improved the outlook of patients with metastatic melanoma. Prior to the approval of checkpoint inhibitors, this strategy was the most promising. However, while response rates of up to 50% have been reported, this strategy is still rather crude. Thus, improvements are needed and within reach. A hallmark of the developing tumor is the evasion of immune destruction. Achieved through the recruitment of immune suppressive cell subsets, upregulation of inhibitory receptors and the development of physical and chemical barriers (such as poor vascularization and hypoxia) leaves the microenvironment a hostile destination for anti-tumor T cells. In this paper, we review the emerging strategies of improving the homing of effector T cells (TILs, CARs, TCR engineered T cells, etc.) through genetic engineering with chemokine receptors matching the chemokines of the tumor microenvironment. While this strategy has proven successful in several preclinical models of cancer and the strategy has moved into the first phase I/II clinical trial in humans, most of these studies show a modest (doubling) increase in tumor infiltration of effector cells, which raises the question of whether road blocks must be tackled for efficient homing. We propose a role for physical exercise in modulating the tumor microenvironment and preparing the platform for infiltration of anti-tumor immune cells. In a time of personalized medicine and genetic engineering, this "old tool" may be a way to augment efficacy and the depth of response to immune therapy.

Hyaluronic acid based low viscosity hydrogel as a novel carrier for Convection Enhanced Delivery of CAR T cells

Convection Enhanced Delivery (CED) infuses therapeutic agents directly into the intracranial area continuously under pressure. The convection improves the distribution of therapeutics such as those aimed at brain tumors. Although CED successfully delivers small therapeutic agents, this technique fails to effectively deliver cells largely due to cell sedimentation during delivery. To overcome this limitation, we have developed a low viscosity hydrogel (LVHydrogel), which is capable of retaining cells in suspension. In this study, we evaluated whether LVHydrogel can effectively act as a carrier for the CED of tumor-specific chimeric antigen receptor (CAR) T cells. CAR T cells were resuspended in saline or LVHydrogel carriers, loaded into syringes, and passed through the CED system for 5 h. CAR T cells submitted to CED were counted and the efficiency of delivery was determined. In addition to delivery, the ability of CAR T cells to migrate and induce cytotoxicity was evaluated. Our studies demonstrate that LVHydrogel is a superior carrier for CED in comparison to saline. The efficiency of cell delivery in saline carrier was only ∼3-5% of the total cells whereas delivery by the LVHydrogel carrier was much higher, reaching ∼45-75%. Migration and Cytotoxicity was similar in both carriers in non-infused samples but we found superior cytotoxicity in LVHydrogel group post-infusion. We demonstrate that LVHydrogel, a biodegradable biomaterial which does not cause acute toxicity on preclinical animal models, prevents cellular sedimentation during CED and presents itself as a superior carrier to the current carrier, saline, for the CED of CAR T cells.

Application of chimeric antigen receptor-engineered T cells in ovarian cancer therapy

Due to the critical role of T cells in the immune surveillance of ovarian cancer, adoptive T-cell therapies are receiving increased attention as an immunotherapeutic approach for ovarian cancer. Chimeric antigen receptors (CARs), constructed by incorporating the single-chain Fv fragment to a T-cell signaling domain such as CD3 ζ or Fc receptor γ chain, endow T cell with nonmajor histocompatibility complex-restricted specificity. Dual specificity, trans-signaling CARs and affinity-tuned single-chain Fv fragment have broadened the applicability of CAR-engineered T-cell therapy and may be considered preferential to T cell receptor T-cell therapy in clinical care. As new insights into the CAR-engineered T cells have emerged over the last decade, we review the development of CAR T-cell therapy and discuss the progress and safety concerns regarding its translation from basic research into clinical care of ovarian cancer.

Indium/Gallium Maltolate Effects on Human Breast Carcinoma Cells: In Vitro Investigation on Cytotoxicity and Synergism with Mitoxantrone

In this study, we aimed to investigate in vitro whether the synthetized indium maltolate (InMal) and gallium maltolate (GaMal) could exert either a toxic effect toward breast cancer cell line MDA-MB-231 or an agonistic activity with mitoxantrone (MTX) in comparison to fibroblast cell line NIH-3T3. Both GaMal and InMal reduced viability of MDA-MB-231, and at a lesser extent of NIH3-T3, in a dose- and time-dependent mode, the outcome was more effective in comparison to MTX sole exposure. Both GaMal and InMal toxicity was reverted by iron citrate addition on NIH3-T3, not on MDA-MB-231, showing indirectly that gallium and indium's mechanisms of action may include iron targeting. The agonistic activity against MDA-MB-231 survival was shown pretreating with 100 μM InMal for 24 h followed by medium exchange with MTX at 10 ng mL^-1 or vice-versa but not with co-incubation of both compounds. In particular, InMal pretreating resulted more protective to MTX subsequent exposure.