Use of retroviral-mediated gene transfer to deliver and test function of chimeric antigen receptors in human T-cells

Chimeric antigen receptors (CARs) are genetically delivered fusion molecules that elicit T-cell activation upon binding of a native cell surface molecule. These molecules can be used to generate a large number of memory and effector T-cells that are capable of recognizing and attacking tumor cells. Most commonly, stable CAR expression is achieved in T-cells using retroviral vectors. In the method described here, retroviral vectors are packaged in a two-step procedure. First, H29D human retroviral packaging cells (a derivative of 293 cells) are transfected with the vector of interest, which is packaged transiently in vesicular stomatitis virus (VSV) G pseudotyped particles. These particles are used to deliver the vector to PG13 cells, which achieve stable packaging of gibbon ape leukaemia virus (GALV)-pseudotyped particles that are suitable for infection of human T-cells. The key advantage of the method reported here is that it robustly generates polyclonal PG13 cells that are 100% positive for the vector of interest. This means that efficient gene transfer may be repeatedly achieved without the need to clone individual PG13 cells for experimental pre-clinical testing. To achieve T-cell transduction, cells must first be activated using a non-specific mitogen. Phytohemagglutinin (PHA) provides an economic and robust stimulus to achieve this. After 48-72 h, activated T-cells and virus-conditioned medium are mixed in RetroNectin-coated plasticware, which enhances transduction efficiency. Transduced cells are analyzed for gene transfer efficiency by flow cytometry 48 h following transduction and may then be tested in several assays to evaluate CAR function, including target-dependent cytotoxicity, cytokine production and proliferation.

Design of a phase I clinical trial to evaluate intratumoral delivery of ErbB-targeted chimeric antigen receptor T-cells in locally advanced or recurrent head and neck cancer

Despite several advances, 5-year survival in patients with head and neck squamous cell carcinoma (HNSCC) remains unchanged at only 50%. The commonest cause of death is locally advanced/recurrent disease. Consequently, there is an unmet need for new approaches to improve local control in HNSCC. T4 immunotherapy is an autologous cell therapy in which peripheral blood T-cells are genetically engineered using a retroviral vector to coexpress two chimeric receptors: (i) T1E28z is a chimeric antigen receptor that engages multiple ErbB dimers that are commonly upregulated in HNSCC; (ii) 4αβ is a chimeric cytokine receptor that converts the weak mitogenic stimulus provided by interleukin (IL)-4 into a strong and selective growth signal, allowing preferential expansion and enrichment of T4(+) T-cells ex vivo. T4 immunotherapy exerts antitumor activity against HNSCC cell lines and tumors in vivo, without significant toxicity. Human T4(+) T-cells also engage mouse ErbB receptors, permitting safety testing in SCID Beige mice. Severe toxicity caused by cytokine release syndrome ensues when human T4(+) T-cells are administered at high doses to mice, particularly with advanced tumor burdens. However, such toxicity is not required for efficacy and is never seen if T-cells are administered by the intratumoral route. To exploit this, we have designed a first-in-man clinical trial in which T4(+) T-cells are administered to patients with locally advanced/recurrent HNSCC. Cells will be administered at a single sitting to multiple sites around the viable tumor circumference. A 3+3 dose escalation design will be used, starting at 10(7) cells (cohort 1), escalating to 10(9) cells (cohort 5). If maximum tolerated dose remains undefined, cohorts 6/7 will receive either low- or high-dose cyclophosphamide before 10(9) T4(+) T-cells. A panel of routine/in-house assays and imaging techniques will be used to monitor safety, efficacy, perturbation of endogenous antitumor immunity, immunogenicity, and T-cell trafficking.

In-vivo testing of PSMA-targeted T-cell immunotherapy for prostate cancer (TUM7P.920)

Introduction: Skeletal metastases are a significant cause of morbidity and mortality and overall greatly affect the quality of life of prostate cancer patients. Examining impact of bone metastasis in vivo remains a significant challenge, as animal models that closely mimic the natural history and malignant progression of clinical prostate cancer are not available. Objectives: To develop an animal model of human metastatic prostate cancer. Once a model has been developed and optimized, it was this to test efficacy of immunotherapy using T-cells that have been genetically targeted against prostate-specific membrane antigen (PSMA). Material and methods: PCR, western blot, flow cytometry and ELISA, we performed functional anaylsis of fucosyltransferase 3(FT3) in PC3LN3(PL)and PC3LN3-PSMA (PLP) tumour cell lines. In vivo bioluminescent imaging (BLI) was used to detect metastases. Results: In preliminary studies, we have observed that delivery of a FT3-encoding retroviral vector to PL and PLP enables them to express sialyl Lewis X and to acquire E-selectin binding activity. We also showed that FT3 promotes increased PLP motility and invasiveness in vitro. Bioluminescent animal model of metastasised prostate cancer is established to determine the effect of this upon their pattern of metastatic spread in SCID Beige mice. Conclusion: We have established an in-vivo model of PSMA-expressing prostate cancer. This will serve as a platform to test immunotherapy using P28z+ T-cells.

Design and preclinical evaluation of a 99mTc-labelled diabody of mAb J591 for SPECT imaging of prostate-specific membrane antigen (PSMA)

BACKGROUND

Sensitive and specific detection of nodal status, sites of metastases and low-volume recurrent disease could greatly improve management of patients with advanced prostate cancer. Prostate-specific membrane antigen (PSMA) is a well-established marker for prostate carcinoma with increased levels of expression in high-grade, hormone-refractory and metastatic disease. The monoclonal antibody (mAb) J591 is directed against an extracellular epitope of PSMA and has been shown to efficiently target disseminated disease including metastases in lymph nodes and bone. Its use as a diagnostic imaging agent however is limited due to its slow pharmacokinetics. In this study a diabody derived from mAb J591 was developed as a single photon emission computed tomography (SPECT) tracer with improved pharmacokinetics for the detection of PSMA expression in prostate cancer.

METHODS

A diabody in VH-VL orientation and with a C-terminal cysteine was expressed in HEK293T cells and purified by a combination of metal ion affinity and size exclusion chromatography. Specificity and affinity were determined in cell binding studies. For SPECT imaging, the diabody was site-specifically labelled with [99mTc(CO)3]+ via the C-terminal His tag and evaluated in a subcutaneous DU145/DU145-PSMA prostate carcinoma xenograft model.

RESULTS

J591C diabody binds to PSMA-expressing cells with low nanomolar affinity (3.3 ± 0.2 nM). SPECT studies allowed imaging of tumour xenografts with high contrast from 4 h post injection (p.i.). Ex vivo biodistribution studies showed peak tumour uptake of the tracer of 12.1% ± 1.7% injected dose (ID)/g at 8 h p.i. with a tumour to blood ratio of 8.0. Uptake in PSMA-negative tumours was significantly lower with 6.3% ± 0.5% at 8 h p.i. (p < 0.001).

CONCLUSION

The presented diabody has favourable properties required to warrant its further development for antibody-based imaging of PSMA expression in prostate cancer, including PSMA-specific uptake, favourable pharmacokinetics compared to the parental antibody and efficient site-specific radiolabelling with 99mTc.

Instability of delay classification and determination of early intervention eligibility in the first two years of life

The purpose of this study was to determine the effectiveness of the Bayley Scales of Infant Development, Third Edition (Bayley-III) to track development and classify delays in low- and high-risk infants across the first two years of life. We assessed cognitive, language, and motor development in 24 low-risk full-term and 30 high-risk preterm infants via seven assessments performed between 3 and 24 months corrected age. The Bayley-III resulted in highly unstable delay classifications, low sensitivities, and poor positive predictive values across time. The results highlight that early intervention professionals, researchers, and policy makers should: (1) emphasize clinical opinion and prevalence of risk factors rather than standardized assessment findings when classifying delays and determining eligibility for services, and (2) develop more effective developmental assessments for infants and young children.

Use of gene-modified regulatory T-cells to control autoimmune and alloimmune pathology: is now the right time?

Adoptive immunotherapy using genetically targeted T-cells has recently begun to achieve impressive clinical impact in selected tumor types. Furthermore, long-term follow-up studies indicate thus far that integrating viral vectors do not elicit clinically evident genotoxicity in T-cells, unlike hematopoietic stem cells. The optimism engendered by this clinical experience provides a platform for consideration of the extended use of this technology in other disease types. One area of particular interest entails the harnessing of regulatory T-cells (Tregs) in order to down-regulate unwanted immune responses. Increasing evidence supports the efficacy of this approach in pre-clinical models of autoimmune disease and allograft rejection. Nonetheless, questions remain about optimal host cell, transgene cargo, phenotypic stability of engineered cells in vivo and potential for toxicity. Here, we review the evidence that genetically engineered Tregs can effectively dampen pathogenic immune responses and critically evaluate the prospects for clinical development of this approach.

Preclinical in vivo modeling of cytokine release syndrome induced by ErbB-retargeted human T cells: identifying a window of therapeutic opportunity?

The ErbB network is dysregulated in many solid tumors. To exploit this, we have developed a chimeric Ag receptor (CAR) named T1E28z that targets several pathogenetically relevant ErbB dimers. T1E28z is coexpressed with a chimeric cytokine receptor named 4αβ (combination termed T4), enabling the selective expansion of engineered T cells using IL-4. Human T4(+) T cells exhibit antitumor activity against several ErbB(+) cancer types. However, ErbB receptors are also expressed in several healthy tissues, raising concerns about toxic potential. In this study, we have evaluated safety of T4 immunotherapy in vivo using a SCID beige mouse model. We show that the human T1E28z CAR efficiently recognizes mouse ErbB(+) cells, rendering this species suitable to evaluate preclinical toxicity. Administration of T4(+) T cells using the i.v. or intratumoral routes achieves partial tumor regression without clinical or histopathologic toxicity. In contrast, when delivered i.p., tumor reduction is accompanied by dose-dependent side effects. Toxicity mediated by T4(+) T cells results from target recognition in both tumor and healthy tissues, leading to release of both human (IL-2/IFN-γ) and murine (IL-6) cytokines. In extreme cases, outcome is lethal. Both toxicity and IL-6 release can be ameliorated by prior macrophage depletion, consistent with clinical data that implicate IL-6 in this pathogenic event. These data demonstrate that CAR-induced cytokine release syndrome can be modeled in mice that express target Ag in an appropriate distribution. Furthermore, our findings argue that ErbB-retargeted T cells can achieve therapeutic benefit in the absence of unacceptable toxicity, providing that route of administration and dose are carefully optimized.

Synergistic Chemoimmunotherapy of Epithelial Ovarian Cancer Using ErbB-Retargeted T Cells Combined with Carboplatin

Epithelial ovarian cancer (EOC) remains the most lethal gynecologic malignancy, underscoring the need for better therapies. Adoptive immunotherapy using genetically targeted T cells represents a promising new treatment for hematologic malignancies. However, solid tumors impose additional obstacles, including the lack of suitable targets for safe systemic therapy and the need to achieve effective T cell homing to sites of disease. Because EOC undergoes transcœlomic metastasis, both of these challenges may be circumvented by T cell administration to the peritoneal cavity. In this study, we describe such an immunotherapeutic approach for EOC, in which human T cells were targeted against the extended ErbB family, using a chimeric Ag receptor named T1E28z. T1E28z was coexpressed with a chimeric cytokine receptor named 4αβ (combination termed T4), enabling the selective ex vivo expansion of engineered T cells using IL-4. Unlike control T cells, T4(+) T cells from healthy donors and patients with EOC were activated by and destroyed ErbB(+) EOC tumor cell lines and autologous tumor cultures. In vivo antitumor activity was demonstrated in mice bearing established luciferase-expressing SKOV-3 EOC xenografts. Tumor regression was accompanied by mild toxicity, manifested by weight loss. Although efficacy was transient, therapeutic response could be prolonged by repeated T cell administration. Furthermore, prior treatment with noncytotoxic doses of carboplatin sensitized SKOV-3 tumors to T4 immunotherapy, promoting enhanced disease regression using lower doses of T4(+) T cells. By combining these approaches, we demonstrate that repeated administration of carboplatin followed by T4(+) T cells achieved optimum therapeutic benefit in the absence of significant toxicity, even in mice with advanced tumor burdens.

Role of the clinical immunology laboratory in disease monitoring

Immunological investigations provide useful information to guide diagnosis of several disorders. Many such tests are also commonly repeated at intervals, in an effort to facilitate disease monitoring. In general however, immunology test results are often slow to alter. Furthermore, audit activity has indicated that repeated testing accounts for a substantial workload in many immunology services, which may waste resources and compromise the efficient completion of necessary tests. Consequently, the need and appropriate minimum interval between repeated testing requires critical evaluation. In this review, the clinical utility of repeated performance of several common immunology investigations has been evaluated, based upon published evidence. In some cases (e.g., paraprotein quantification, or measurement of anti-glomerular basement membrane antibodies), repeated testing provides vital clinical information and can be justified on a frequent and individualized basis. However, many other investigations provided by immunology services provide less valuable information when used to aid disease monitoring rather than diagnosis. It is hoped that the data summarized here will facilitate a more evidence-based approach to repeated testing. Such information may also assist with the local implementation of demand management strategies based upon setting of minimum retesting intervals for these investigations.

Whole-body imaging of adoptively transferred T cells using magnetic resonance imaging, single photon emission computed tomography and positron emission tomography techniques, with a focus on regulatory T cells

Cell-based therapies using natural or genetically modified regulatory T cells (T(regs)) have shown significant promise as immune-based therapies. One of the main difficulties facing the further advancement of these therapies is that the fate and localization of adoptively transferred T(regs) is largely unknown. The ability to dissect the migratory pathway of these cells in a non-invasive manner is of vital importance for the further development of in-vivo cell-based immunotherapies, as this technology allows the fate of the therapeutically administered cell to be imaged in real time. In this review we will provide an overview of the current clinical imaging techniques used to track T cells and T(regs) in vivo, including magnetic resonance imaging (MRI) and positron emission tomography (PET)/single photon emission computed tomography (SPECT). In addition, we will discuss how the finding of these studies can be used, in the context of transplantation, to define the most appropriate T(reg) subset required for cellular therapy.

Implementing improved post-treatment care for cancer survivors in England, with reflections from Australia, Canada and the USA

Increasing cancer incidence together with improved survival rates are contributing to the growing number of cancer survivors. Survivors may encounter a range of potential effects as a result of the cancer itself or cancer treatments. Traditionally, the major focus of follow-up care has been on detection of cancer recurrence; however, the efficacy of such strategies is questionable. Traditional follow-up frequently fails to identify or adequately address many survivors’ concerns. Aftercare needs to be planned to enable better outcomes for survivors, while using scarce health-care resources efficiently. This review focuses on provision of survivorship care, rather than on research. England’s National Cancer Survivorship Initiative has developed principles for improved care of those living with and beyond cancer. These include risk-stratified pathways of care, the use of treatment summaries and care plans, information and education to enable choice and the confidence to self manage, rapid re-access to specialist care, remote monitoring and well-coordinated care. Many of these principles are relevant internationally, though preferred models of care will depend on local circumstances.

Immunotherapy of malignant disease using chimeric antigen receptor engrafted T cells

Chimeric antigen receptor- (CAR-) based immunotherapy has been under development for almost 25 years, over which period it has progressed from a new but cumbersome technology to an emerging therapeutic modality for malignant disease. The approach involves the genetic engineering of fusion receptors (CARs) that couple the HLA-independent binding of cell surface target molecules to the delivery of a tailored activating signal to host immune cells. Engineered CARs are delivered most commonly to peripheral blood T cells using a range of vector systems, most commonly integrating viral vectors. Preclinical refinement of this approach has proceeded over several years to the point that clinical testing is now being undertaken at several centres, using increasingly sophisticated and therapeutically successful genetic payloads. This paper considers several aspects of the pre-clinical and clinical development of CAR-based immunotherapy and how this technology is acquiring an increasing niche in the treatment of both solid and haematological malignancies.

Dual antiplatelet therapy for primary and secondary prevention

The concomitant use of aspirin and an ADP receptor (P2Y12) blocker, also known as dual antiplatelet therapy (DAPT), has been extensively investigated as a primary and secondary prevention strategy in an effort to reduce the risk of cardiovascular events. In this manuscript the authors review the current guideline recommendations for DAPT and discuss the scientific data that supports these recommendations. Reported are also the scientific knowledge gaps and how future studies are likely to delineate these issues. Incremental knowledge is not likely to be an alternative to individualized care provided by the astute clinician to his patient. In consideration for prescribing DAPT (drug, dosage and duration) the clinician will have to weigh the potential benefits (reduction in death from cardiovascular causes, nonfatal myocardial infarction, and nonfatal stroke) and risks (severe or life-threatening bleeding) for each and every patient.

Fractional flow reserve (FFR): changing the practice of interventional cardiology

Fractional flow reserve (FFR) has become an extremely valuable tool for assessing the hemodynamic significance of intermediate coronary lesions. This manuscript delineates the current guidelines regarding the use of FFR and discusses emerging indications for the use of this diagnostic tool and how they compare with and complement non-invasive or other invasive diagnostic modalities. The manuscript addresses some of the key unanswered questions related to FFR, the potential pitfalls of this tool and discusses future directions of use and research.

Emerging oral anticoagulants for stroke prevention in patients with non-valvular atrial fibrillation

In patients with atrial fibrillation (AF) warfarin has been the mainstay therapy for stroke prevention. In recent randomized clinical trials (RCTs) oral direct thrombin inhibitor (Dabigatran) and factor Xa inhibitors (Rivaroxaban and Apixaban) challenged the efficacy and safety benchmarks set by warfarin. These drugs boast a rapid onset of action, shorter half-life and fewer drug and dietary interactions. Moreover, these new anticoagulants do not require monitoring, titration or dose adjustments. These agents have already been approved for prevention of stroke or systemic embolism in patients with AF. Uncertainty regarding suitability, efficacy and safety in certain patient subsets and issues related to the ability effectively monitor the pharmacodynamic effects and reverse the therapeutic effects of these drugs should be addressed as we engage in a widespread use of these agents in various patient subsets.

Flexible targeting of ErbB dimers that drive tumorigenesis by using genetically engineered T cells

Pharmacological targeting of individual ErbB receptors elicits antitumor activity, but is frequently compromised by resistance leading to therapeutic failure. Here, we describe an immunotherapeutic approach that exploits prevalent and fundamental mechanisms by which aberrant upregulation of the ErbB network drives tumorigenesis. A chimeric antigen receptor named T1E28z was engineered, in which the promiscuous ErbB ligand, T1E, is fused to a CD28 + CD3ζ endodomain. Using a panel of ErbB-engineered 32D hematopoietic cells, we found that human T1E28z⁺ T cells are selectively activated by all ErbB1-based homodimers and heterodimers and by the potently mitogenic ErbB2/3 heterodimer. Owing to this flexible targeting capability, recognition and destruction of several tumor cell lines was achieved by T1E28⁺ T cells in vitro, comprising a wide diversity of ErbB receptor profiles and tumor origins. Furthermore, compelling antitumor activity was observed in mice bearing established xenografts, characterized either by ErbB1/2 or ErbB2/3 overexpression and representative of insidious or rapidly progressive tumor types. Together, these findings support the clinical development of a broadly applicable immunotherapeutic approach in which the propensity of solid tumors to dysregulate the extended ErbB network is targeted for therapeutic gain.