Highly effective liquid and solid phase extraction methods to concentrate radioiodine isotopes for radioiodination chemistry

Radioactive iodine isotopes play a pivotal role in radiopharmaceuticals. Large-scale production of multi-patient dose of radioiodinated nuclear medicines requires high concentration of radioiodine. We demonstrate that tetrabutylammonium chloride and methyltrioctylamonium chloride are effective phase transfer reagents to concentrate iodide-124, iodide-125 and iodide-131 from the corresponding commercial water solutions. The resulting concentrated radioiodide, in the presence of either phase transfer reagent, does not hamper the chemical reactivity of aqueous radioiodide in the copper (II)-mediated one-pot three-component click chemistry to produce radioiodinated iodotriazoles.

Synergistic T cell signaling by 41BB and CD28 is optimally achieved by membrane proximal positioning within parallel chimeric antigen receptors

Second generation (2G) chimeric antigen receptors (CARs) contain a CD28 or 41BB co-stimulatory endodomain and elicit remarkable efficacy in hematological malignancies. Third generation (3G) CARs extend this linear blueprint by fusing both co-stimulatory units in series. However, clinical impact has been muted despite compelling evidence that co-signaling by CD28 and 41BB can powerfully amplify natural immune responses. We postulate that effective dual co-stimulation requires juxta-membrane positioning of endodomain components within separate synthetic receptors. Consequently, we designed parallel (p)CARs in which a 2G (CD28+CD3ζ) CAR is co-expressed with a 41BB-containing chimeric co-stimulatory receptor. We demonstrate that the pCAR platform optimally harnesses synergistic and tumor-dependent co-stimulation to resist T cell exhaustion and senescence, sustaining proliferation, cytokine release, cytokine signaling, and metabolic fitness upon repeated stimulation. When engineered using targeting moieties of diverse composition, affinity, and specificity, pCAR T cells consistently elicit superior anti-tumor activity compared with T cells that express traditional linear CARs.

TGF-β1 potentiates Vγ9Vδ2 T cell adoptive immunotherapy of cancer

Despite its role in cancer surveillance, adoptive immunotherapy using γδ T cells has achieved limited efficacy. To enhance trafficking to bone marrow, circulating Vγ9Vδ2 T cells are expanded in serum-free medium containing TGF-β1 and IL-2 (γδ[T2] cells) or medium containing IL-2 alone (γδ[2] cells, as the control). Unexpectedly, the yield and viability of γδ[T2] cells are also increased by TGF-β1, when compared to γδ[2] controls. γδ[T2] cells are less differentiated and yet display increased cytolytic activity, cytokine release, and antitumor activity in several leukemic and solid tumor models. Efficacy is further enhanced by cancer cell sensitization using aminobisphosphonates or Ara-C. A number of contributory effects of TGF-β are described, including prostaglandin E2 receptor downmodulation, TGF-β insensitivity, and upregulated integrin activity. Biological relevance is supported by the identification of a favorable γδ[T2] signature in acute myeloid leukemia (AML). Given their enhanced therapeutic activity and compatibility with allogeneic use, γδ[T2] cells warrant evaluation in cancer immunotherapy.

Prospects for Development of Induced Pluripotent Stem Cell-Derived CAR-Targeted Immunotherapies

Technologies required to generate induced pluripotent stem cells (iPSC) were first described 15 years ago, providing a strong impetus to the field of regenerative medicine. In parallel, immunotherapy has finally emerged as a clinically meaningful modality of cancer therapy. In particular, impressive efficacy has been achieved in patients with selected haematological malignancies using ex vivo expanded autologous T cells engineered to express chimeric antigen receptors (CARs). While solid tumours account for over 90% of human cancer, they currently are largely refractory to this therapeutic approach. Nonetheless, given the considerable innovation taking place worldwide in the CAR field, it is likely that effective solutions for common solid tumours will emerge in the near future. Such a development will create significant new challenges in the scalable delivery of these complex, costly and individualised therapies. CAR-engineered immune cell products that originate from iPSCs offer the potential to generate unlimited numbers of homogeneous, standardised cell products in which multiple defined gene modification events have been introduced to ensure safety, potency and reproducibility. Here, we review some of the emerging strategies in use to engineer CAR-expressing iPSC-derived drug products.

124 OUTCOME OF SPEECH AND LANGUAGE THERAPY CLINICAL DYSPHAGIA ASSESSMENT FOLLOWING AN INTERDISCIPLINARY SWALLOW SCREEN

Background

A 7 question non-validated swallow screen (Any reported swallowing difficulties? Any coughing with food or fluids? Any choking? Does food get stuck when eating? Any recurrent chest infections? Any pain when swallowing? Any difficulty swallowing tablets?) is used by an integrated care team for older persons to prioritise referrals to the Speech and Language Therapy (SLT) service.

This study identified the proportion of patients screened who appropriately required a clinical dysphagia assessment and intervention.

Methods

This was a retrospective study from September 2020 to June 2021. Patients were assessed by the Clinical Specialist SLT who determined if swallow impairment was present and whether intervention was required. Age, gender and clinical frailty score were documented. Patients who resided out of the catchment area or who had already received an SLT service were excluded.

Results

The average age was 80 years, range 67–103. The male to female ratio was 2:1 and the average clinical frailty score (CFS) was 5. N = 42(32%) screened positive. N = 29(69%) attended for SLT assessment. N = 27(93.1%) had a swallow impairment identified. N = 20 were discharged following a single intervention and 9 required further SLT intervention.

Conclusion

Presbyphagia is generally asymptomatic and results from age related anatomical and physiological changes, reduced functional reserve and sarcopenia. Older adults compensate for these difficulties and do not seek assistance. Presbyphagia may progress to dysphagia, resulting in adverse outcomes. The high rate of SLT confirmed swallow impairment and need for SLT intervention highlights a need to prospectively refine and validate this 7 question swallow screen.

179 WHAT MATTERS TO THE FRAIL OLDER PERSON CHANGES DURING COVID-19 AND SHOULD INFORM PATIENT CENTRED CHANGE

Background

Methods

Results

Conclusion

44 BONE HEALTH AND FRACTURE RISK: KNOWLEDGE, OPINION AND PRACTICE OF PHYSIOTHERAPISTS

Background

Osteoporotic-related fractures are responsible for excess mortality, morbidity, chronic pain, reduction in quality of life, admission to long-term care and health and social care costs (Papaioannou et al, 2010).

Evidence for using Fracture Risk Assessment Tool (FRAX®) based community-screening in older people is increasing (Kanis et al, 2020). There is no published evidence on the use of FRAX® by Physiotherapists.

Methods

A questionnaire was sent to South Eastern Branch members of the Irish Society of Chartered Physiotherapists (ISCP).

Survey themes were: participant characteristics, knowledge and opinion in the areas of Bone Health and Fracture Risk. Responses were downloaded from Survey Monkey and analysed using descriptive statistics.

Results

The response rate was 27% (n = 56). 72% (n = 40) of those surveyed had at least 10 years clinical experience. For 65% (n = 37) of participants, older people made up more than half of their clinical caseload. 96% (n = 54) of participants treated people with frailty and other bone health risk factors; falls (93%), osteoporosis (89%), fracture or reduced mobility (87%).

On a scale of 1–10 (1 = least confident, 10 = most confident) 49% of respondents rated confidence in prescribing Bone Health Physiotherapy interventions at ≤5.

When interpreting results of a DEXA scan; 80% reported confidence to be ≤5.

Half (49%) of participants had never heard of FRAX®.

95% of respondents felt fracture risk was under addressed in clinical practice. All felt it was within their professional responsibility to discuss fracture risk with patients.

Conclusion

This is the first evaluation of bone health and fracture risk knowledge, opinion and practice of physiotherapists. The need for more knowledge of DEXA, FRAX® and bone health was highlighted. The use of FRAX® may improve fracture risk assessment in patients attending Physiotherapy. Based on these results, FRAX® has been introduced into a Rehabilitation Unit by Physiotherapists as part of Quality Improvement Project.

126 A QUALITY INITIATIVE TO IMPROVE THE ASSESSMENT AND RECOMMENDATION FOR TOTAL CALCIUM INTAKE

Background

This study assessed factors affecting adherence to calcium supplementation, estimated total calcium intake and potential to increase dietary calcium in the frail older adult.

Methods

Frail Older Adults who completed a comprehensive geriatric assessment (CGA) between January—June 2021 were included. Those taking calcium supplements were telephoned by a Dietitian. Nursing home residents, hospital inpatients and those unable to complete a telephone questionnaire were excluded. A modified version of the Short Calcium Intake List (SCAIL) was used and potential to improve dietary calcium was assessed (1). Data was analysed using descriptive statistics.

Results

N = 50 patients were taking a calcium supplement. N = 15 were excluded. 26 women and 9 men, aged 70 -96 yrs were included. Dietary intake ranged from 250– 1904 mg. 17% (N = 6) achieved >1,000 mg/day dietary calcium requirements from diet. 66% (N = 23) had potential to increase their dietary calcium. 97% (N = 34) were prescribed a Calcium supplement, ranging from 500– 2000 mg/day. Total Calcium Intake including supplementation ranged from 850 mg—2,737 mg. 82% (N = 29) exceeded their daily requirements.40% (N = 14) reported reduced compliance due to swallowing difficulties; 25%(N = 9) gastrointestinal upset; 11% (N = 4,) taste/consistency and 8% forgetting (N = 3).Dietitian recommendations included 31% (N = 11) to stop supplementation, 34% (N = 12) to reduce, 11% (N = 4) advice on managing concerns relating to supplement and 22% (N = 8) dietary education.

Conclusion

Most older adults did not meet their nutritional requirements for dietary calcium. Over two thirds could reduce or stop supplementation following dietary calcium assessment and advice. A dietary calcium estimator for the older adult, with education can be used to correct calcium intake. This modified SCAIL will be integrated into the CGA as part of a quality improvement initiative for the frail older adult.

Reference

1. Rasch L et al. (2017), Content Validity of a Short Calcium Intake List to Estimate Daily Dietary Calcium intake of Patients with Osteoporosis, Calcified Tissue International, 100(3): 271–277.

Closing the Osteoporotic-Fracture Care Gap for Frail Older Persons

Aim To implement standardised fracture risk assessment in the frail older person. Methods Frail older patients underwent opportunistic screening for fracture risk. Roadblocks to standardised assessment were identified. An Integrated Care Team for older persons (ICT) trained in fracture risk assessment using FRAX. Clinical assessment was via a locally agreed algorithm. Data was entered onto Excel. The SQUIRE guidelines for quality improvement programmes were used to report the results. Results Of 96 patients opportunistically screened, the average age was 84 years. FRAX was completed for 19% (n=18). 89% (n=16) met the pharmacotherapy threshold. Nine were recommended pharmacotherapy. Of sixteen patients recommended for DXA, just 31% (n=5) were booked. Following implementation of a quality improvement project, 100 patients were assessed, and average age was 80 years. FRAX was completed for 62% (n=63) and 95% (n=60) required pharmacotherapy. 24% (n=14) had untreated prior fracture. All had pharmacotherapy prescribed. 59% (n=59) required DXA scanning. 70% (n=41) had DXA ordered. Conclusion ICT ownership increased FRAX assessment 3-fold and point of contact prescribing to 100%.

Development and Validation of a Good Manufacturing Process for IL-4-Driven Expansion of Chimeric Cytokine Receptor-Expressing CAR T-Cells

Adoptive cancer immunotherapy using chimeric antigen receptor (CAR) engineered T-cells holds great promise, although several obstacles hinder the efficient generation of cell products under good manufacturing practice (GMP). Patients are often immune compromised, rendering it challenging to produce sufficient numbers of gene-modified cells. Manufacturing protocols are labour intensive and frequently involve one or more open processing steps, leading to increased risk of contamination. We set out to develop a simplified process to generate autologous gamma retrovirus-transduced T-cells for clinical evaluation in patients with head and neck cancer. T-cells were engineered to co-express a panErbB-specific CAR (T1E28z) and a chimeric cytokine receptor (4αβ) that permits their selective expansion in response to interleukin (IL)-4. Using peripheral blood as starting material, sterile culture procedures were conducted in gas-permeable bags under static conditions. Pre-aliquoted medium and cytokines, bespoke connector devices and sterile welding/sealing were used to maximise the use of closed manufacturing steps. Reproducible IL-4-dependent expansion and enrichment of CAR-engineered T-cells under GMP was achieved, both from patients and healthy donors. We also describe the development and approach taken to validate a panel of monitoring and critical release assays, which provide objective data on cell product quality.

Approaches for refining and furthering the development of CAR-based T cell therapies for solid malignancies

Introduction: Chimeric antigen receptor-engineered T-cells typically use the binding domains of antibodies to target cytotoxicity toward tumors. This approach has produced great efficacy against selected hematological cancers, but benefit in solid tumors has been limited. Characteristically, the microenvironment in solid tumors restricts CAR T cell function, thereby limiting success. Enhancing efficacy will depend on novel target discovery to refine specificity and reduce toxicity. Additionally, overcoming immunosuppressive mechanisms may be achieved by altering the structure of the CAR itself, together with ancillary gene expression or additional therapeutic interventions.Areas covered: Herein, the authors discuss approaches for refining and further developing CAR T cell therapies specifically for use with solid malignancies. The authors survey the existing literature and provide perspectives for the future.Expert opinion: Pronounced efficacy in solid tumors will likely require combination therapies, targeting both the tumor itself and associated immunosuppressive mechanisms. Future exploration of CAR T cell therapies for solid tumors is likely to incorporate next-generation designs that couple more precise targeting of cancer-associated targets with enhanced potency and resistance to exhaustion.

How Can We Engineer CAR T Cells to Overcome Resistance?

Chimeric antigen receptor (CAR) T cell therapy has achieved unrivalled success in the treatment of B cell and plasma cell malignancies, with five CAR T cell products now approved by the US Food and Drug Administration (FDA). However, CAR T cell therapies for solid tumours have not been nearly as successful, owing to several additional challenges. Here, we discuss mechanisms of tumour resistance in CAR T cell therapy and the emerging strategies that are under development to engineer CAR T cells to overcome resistance.

Abstract PO-039: Radiation therapy enhances anti-tumor activity of a MET CAR T-based immunotherapy approach for glioblastoma multiforme

Glioblastoma multiforme (GBM) is the most prevalent primary malignant brain tumor, which has an aggressive phenotype and mostly fatal recurrence after standard therapy. MET, the hepatocyte growth factor (HGF) receptor is a relevant target for GBM treatment as it is expressed in up to 50% of cases and its expression, which may be induced by radiation therapy (RT), can potentially contribute to RT-resistance of GBM stem cells, and tumor recurrence. MET-based chimeric antigen (CAR) T cell therapy is currently being evaluated in several solid tumor working settings. A combination of T cell-based therapies with RT may improve the efficacy of the CAR T cell therapy through by the RT-induced immune activation via release of cytokines and induction of antigen expression, similarly as has been observed when combining RT with immune checkpoint inhibitors. Here we investigated the combination of MET-targeting CAR T cells with RT for GBM treatment, hypothesizing enhanced anti-tumor effects. The current study used a panel of MET-proficient and MET-deficient human GBM and GBM stem-like cell lines. Cells have been irradiated with a single dose of 0, 2, 5, or 10 Gy and RT impact on MET expression has been assessed at various time points after RT administration. Results show MET increase after RT in some cell lines. To test MET-targeting CAR T effect on the GBM cell lines, CAR constructs that are based on HGF-MET binding elements have been introduced into virus-producing cells and used for human T cells transduction to generate MET-targeting CAR T cells. CAR T cells co-cultured with GBM cell lines in vitro have specifically and significantly decreased viability of MET-positive cancer cells. Data resulting from combination of RT and CAR T cells treatment suggest that radiation exhibits an enhancement of CAR T cells anti-tumor killing activity, indicating a synergism between the two modalities. In conclusion, our data are the first to indicate the efficacy of a MET-based CAR T immunotherapy approach in GBM cell lines. The results also demonstrate a basis for the combination of a MET CAR T modality together with RT. The mechanisms for understanding the interaction between RT and the MET CAR T cells are under investigation.

Citation Format: Lusine Hovhannisyan, Daniel M. Aebersold, John Maher, Adrian F. Ochsenbein, Carsten Riether, Michaela Medova, Yitzhak Zimmer. Radiation therapy enhances anti-tumor activity of a MET CAR T-based immunotherapy approach for glioblastoma multiforme [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr PO-039.

An overview of CAR T-cell clinical trial activity to 2021

Immunotherapy of cancer using chimeric antigen receptor-engineered T-cells has transformed the management of selected haematological malignancies, triggering intense clinical trial activity in this arena. This article summarises trial activity that has been published to date across the spectrum of haematological and solid tumour types.

Chimeric Antigen Receptor T Cells Targeting Integrin αvβ6 Expressed on Cholangiocarcinoma Cells

Cholangiocarcinoma (CCA) is a lethal bile duct cancer that responds poorly to current standard treatments. A new therapeutic approach is, therefore, urgently needed. Adoptive T cell transfer using chimeric antigen receptor (CAR) T cells is a new therapeutic modality with demonstrated efficacy in hematologic malignancies. However, its efficacy against solid tumors is modest, and further intensive investigation continues. An important factor that influences the success of CAR T cell therapy is the selection of a target antigen that is highly expressed on cancer cells, but markedly less so in normal cells. Integrin αvβ6 is upregulated in several solid tumors, but is minimally expressed in normal epithelial cells, which suggests integrin αvβ6 as an attractive target antigen for CAR T cell immunotherapy in CCA. We investigated integrin αvβ6 expression in pathological tissue samples from patients with liver fluke-associated CCA. We then created CAR T cells targeting integrin αvβ6 and evaluated their anti-tumor activities against CCA cells. We found overexpression of the integrin αvβ6 protein in 23 of 30 (73.3%) CCA patient tissue samples. Significant association between high integrin αvβ6 expression and short survival time (p = 0.043) was also observed. Lentiviral constructs were engineered to encode CARs containing an integrin αvβ6-binding peptide (A20) derived from foot-and-mouth disease virus fused with a second-generation CD28/CD3ζ signaling domain (A20-2G CAR) or with a fourth-generation CD28/4-1BB/CD27/CD3ζ signaling domain (A20-4G CAR). The A20-2G and A20-4G CARs were highly expressed in primary human T cells transduced with the engineered lentiviruses, and they exhibited high levels of cytotoxicity against integrin αvβ6-positive CCA cells (p < 0.05). Interestingly, the A20-2G and A20-4G CAR T cells displayed anti-tumor function against integrin αvβ6-positive CCA tumor spheroids (p < 0.05). Upon specific antigen recognition, A20-4G CAR T cells produced a slightly lower level of IFN-γ, but exhibited higher proliferation than A20-2G CAR T cells. Thus, the A20-4G CAR T cells with lower level of cytokine production, but with higher proliferation represents a promising potential adoptive T cell therapy for integrin αvβ6-positive CCA.

Crosstown Traffic: Lymphodepleting Chemotherapy Drives CAR T Cells

CAR-engineered T cell immunotherapy has proven transformative in selected hematological malignancies. However, solid tumors largely remain impervious to these approaches. In addressing this challenge, Srivastava et al. in this issue demonstrate that oxaliplatin-based lymphodepleting chemotherapy promotes enhanced CAR T cell recruitment to lung tumors, boosting therapeutic impact in combination with anti-PD-L1.

T cell response to SARS-CoV-2 infection in humans: A systematic review

BACKGROUND

Understanding the T cell response to SARS-CoV-2 is critical to vaccine development, epidemiological surveillance and disease control strategies. This systematic review critically evaluates and synthesises the relevant peer-reviewed and pre-print literature published from 01/01/2020-26/06/2020.

METHODS

For this systematic review, keyword-structured literature searches were carried out in MEDLINE, Embase and COVID-19 Primer. Papers were independently screened by two researchers, with arbitration of disagreements by a third researcher. Data were independently extracted into a pre-designed Excel template and studies critically appraised using a modified version of the MetaQAT tool, with resolution of disagreements by consensus. Findings were narratively synthesised.

RESULTS

61 articles were included. 55 (90%) studies used observational designs, 50 (82%) involved hospitalised patients with higher acuity illness, and the majority had important limitations. Symptomatic adult COVID-19 cases consistently show peripheral T cell lymphopenia, which positively correlates with increased disease severity, duration of RNA positivity, and non-survival; while asymptomatic and paediatric cases display preserved counts. People with severe or critical disease generally develop more robust, virus-specific T cell responses. T cell memory and effector function has been demonstrated against multiple viral epitopes, and, cross-reactive T cell responses have been demonstrated in unexposed and uninfected adults, but the significance for protection and susceptibility, respectively, remains unclear.

CONCLUSION

A complex pattern of T cell response to SARS-CoV-2 infection has been demonstrated, but inferences regarding population level immunity are hampered by significant methodological limitations and heterogeneity between studies, as well as a striking lack of research in asymptomatic or pauci-symptomatic individuals. In contrast to antibody responses, population-level surveillance of the T cell response is unlikely to be feasible in the near term. Focused evaluation in specific sub-groups, including vaccine recipients, should be prioritised.

Antibody response to SARS-CoV-2 infection in humans: A systematic review

BACKGROUND

Progress in characterising the humoral immune response to Severe Acute Respiratory Syndrome 2 (SARS-CoV-2) has been rapid but areas of uncertainty persist. Assessment of the full range of evidence generated to date to understand the characteristics of the antibody response, its dynamics over time, its determinants and the immunity it confers will have a range of clinical and policy implications for this novel pathogen. This review comprehensively evaluated evidence describing the antibody response to SARS-CoV-2 published from 01/01/2020-26/06/2020.

METHODS

Systematic review. Keyword-structured searches were carried out in MEDLINE, Embase and COVID-19 Primer. Articles were independently screened on title, abstract and full text by two researchers, with arbitration of disagreements. Data were double-extracted into a pre-designed template, and studies critically appraised using a modified version of the Public Health Ontario Meta-tool for Quality Appraisal of Public Health Evidence (MetaQAT) tool, with resolution of disagreements by consensus. Findings were narratively synthesised.

RESULTS

150 papers were included. Most studies (113 or 75%) were observational in design, were based wholly or primarily on data from hospitalised patients (108, 72%) and had important methodological limitations. Few considered mild or asymptomatic infection. Antibody dynamics were well described in the acute phase, up to around three months from disease onset, but the picture regarding correlates of the antibody response was inconsistent. IgM was consistently detected before IgG in included studies, peaking at weeks two to five and declining over a further three to five weeks post-symptom onset depending on the patient group; IgG peaked around weeks three to seven post-symptom onset then plateaued, generally persisting for at least eight weeks. Neutralising antibodies were detectable within seven to 15 days following disease onset, with levels increasing until days 14-22 before levelling and then decreasing, but titres were lower in those with asymptomatic or clinically mild disease. Specific and potent neutralising antibodies have been isolated from convalescent plasma. Cross-reactivity but limited cross-neutralisation with other human coronaviridae was reported. Evidence for protective immunity in vivo was limited to small, short-term animal studies, showing promising initial results in the immediate recovery phase.

CONCLUSIONS

Literature on antibody responses to SARS-CoV-2 is of variable quality with considerable heterogeneity of methods, study participants, outcomes measured and assays used. Although acute phase antibody dynamics are well described, longer-term patterns are much less well evidenced. Comprehensive assessment of the role of demographic characteristics and disease severity on antibody responses is needed. Initial findings of low neutralising antibody titres and possible waning of titres over time may have implications for sero-surveillance and disease control policy, although further evidence is needed. The detection of potent neutralising antibodies in convalescent plasma is important in the context of development of therapeutics and vaccines. Due to limitations with the existing evidence base, large, cross-national cohort studies using appropriate statistical analysis and standardised serological assays and clinical classifications should be prioritised.

Lymphodepletion strategies to potentiate adoptive T-cell immunotherapy - what are we doing; where are we going?

INTRODUCTION

Adoptive immunotherapy of cancer has evolved from the use of ex vivo expanded lymphokine-activated killer cells and tumor-infiltrating lymphocytes to an increasing array of approaches involving genetically engineered T-cells. A pivotal advance in the enablement of these therapies has been the conditioning of patients with lymphodepleting chemotherapy.A broad range of lymphodepleting regimens has been employed in an effort to improve response rates, without any single consistent approach having emerged. Only a limited number of studies involving small numbers of patients has directly compared two or more regimens, making it challenging to infer which are the preferred agents and dosing schedules. This difficulty is compounded by the fact that both response rate and toxicity appear to be disease-, patient- and T-cell product specific.

EXPERT OPINION

This article surveys clinical experience with lymphodepleting regimens that have been used in conjunction with adoptive T-cell immunotherapy, focussing in particular on studies where different approaches have been employed. Harnessing this limited and evolving clinical experience, we set out to provide potential insights into how an optimal balance may be achieved between efficacy and safety. Intermediate dose fludarabine-based regimens are emerging as an increasingly popular option in an attempt to achieve this goal, although further studies are required to provide definitive evidence.

Developing a safe and effective CAR T-cell immunotherapy for breast cancer: progress and pitfalls

Current targeted therapies for breast cancer include hormone inhibitors, monoclonal antibodies and tyrosine kinase inhibitors. However, a significant unmet therapeutic need remains for refractory disease and in particular for the triple negative subtype, which lacks hormone receptors and HER2. Chimeric antigen receptors T cells are genetically engineered to deploy selective cytolytic activity against cells that express cognate native target. Durable remissions have been achieved in refractory hematological malignancies but similar success against solid tumors remains elusive. Several hurdles hinder progress, including the need to identify safe antigens, promote T-cell homing to tumor sites and to ensure the persistence of functional chimeric antigen receptors T cells within the immunosuppressive tumor microenvironment. Perspectives to enable the attainment of this goal are presented in this review.

Engineering of chimeric natural killer cell receptors to develop precision adoptive immunotherapies for cancer

Natural killer (NK) cells are innate immune effectors which play a crucial role in recognizing and eliminating virally infected and cancerous cells. They effectively distinguish between healthy and distressed self through the integration of signals delivered by germline‐encoded activating and inhibitory cell surface receptors. The frequent up‐regulation of stress markers on genetically unstable cancer cells has prompted the development of novel immunotherapies that exploit such innate receptors. One prominent example entails the development of chimeric antigen receptors (CAR) that detect cell surface ligands bound by NK receptors, coupling this engagement to the delivery of tailored immune activating signals. Here, we review strategies to engineer CARs in which specificity is conferred by natural killer group 2D (NKG2D) or other NK receptor types. Multiple preclinical studies have demonstrated the remarkable ability of chimeric NK receptor‐targeted T cells and NK cells to effectively and specifically eliminate cancer cells and to reject established tumour burdens. Importantly, such systems act not only acutely but, in some cases, they also incite immunological memory. Moreover, CARs targeted with the NKG2D ligand binding domain have also been shown to disrupt the tumour microenvironment, through the targeting of suppressive T regulatory cells, myeloid‐derived suppressor cells and tumour vasculature. Collectively, these findings have led to the initiation of early‐phase clinical trials evaluating both autologous and allogeneic NKG2D‐targeted CAR T cells in the haematological and solid tumour settings.

The eIF4A inhibitor silvestrol sensitizes T-47D ductal breast carcinoma cells to external-beam radiotherapy

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Treatment of T-47D breast cancer cells with silvestrol sensitised them to radiation.

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1 nM silvestrol caused a 34% reduction in cells exposed to 2 Gy.

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Clonogenic assays revealed silvestrol had a dose modifying factor of 1.4.

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Radiation was delivered to the tissue culture plate using a clinical LINAC machine.

Purpose

eIF4A is an RNA helicase that forms part of the machinery of translation initiation.

Proteomic analysis demonstrated eIF4A expression to be at least two-fold greater in a radioresistant derivative of T-47D breast cancer cells compared to parental cells.

Inhibition of eIF4A has previously been shown to re-sensitize lymphomas to chemotherapeutic agents that cause DNA damage.

The objective of this work is to investigate whether inhibition of eIF4A using silvestrol sensitizes breast cancer cells to radiotherapy in tissue culture, using T-47D as a model system.

Methods and materials

T-47D cells were incubated in medium containing 0 nM to 1 nM silvestrol either for 24 h prior to irradiation at 0 Gy to 10 Gy, delivered by linear accelerator (LINAC) or continually for six days post irradiation. MTT viability and clonogenic assays were used to quantify response.

Results

Pre-treatment of T-47D cells with 1 nM silvestrol caused a 34% reduction (p = 0.014) in viability on irradiation at 2 Gy compared to treatment with a DMSO control, as assessed by MTT assay.

Maintenance of cells in 1 nM silvestrol for six days following irradiation at 2 Gy caused a 58% reduction (p = <0.001) in tumor cell viability.

Clonogenic assays performed on cells maintained in 1 nM silvestrol following irradiation showed a dose modifying factor (DMF) of 1.4 (p = <0.001, one-way ANOVA).

Conclusions

Low concentrations of silvestrol sensitize T-47D breast cancer cells to radiation with minimal effects on unirradiated cells. This highlights the possible usefulness of eIF4A inhibition in potentiating radiation-induced damage at the tumor site without causing systemic toxicity.