Bispecific T cell engager-armed T cells targeting integrin ανβ6 exhibit enhanced T cell redirection and antitumor activity in cholangiocarcinoma

Advanced cholangiocarcinoma (CCA) presents a clinical challenge due to limited treatment options, necessitating exploration of innovative therapeutic approaches. Bispecific T cell engager (BTE)-armed T cell therapy shows promise in hematological and solid malignancies, offering potential advantages in safety over continuous BTE infusion. In this context, we developed a novel BTE, targeting CD3 on T cells and integrin αvβ6, an antigen elevated in various epithelial malignancies, on cancer cells. The novel BTE was generated by fusing an integrin αvβ6-binding peptide (A20) to an anti-CD3 (OKT3) single-chain variable fragment (scFv) through a G4S peptide linker (A20/αCD3 BTE). T cells were then armed with A20/αCD3 BTE (A20/αCD3-armed T cells) and assessed for antitumor activity. Our results highlight the specific binding of A20/αCD3 BTE to CD3 on T cells and integrin αvβ6 on target cells, effectively redirecting T cells towards these targets. After co-culture, A20/αCD3-armed T cells exhibited significantly heightened cytotoxicity against integrin αvβ6-expressing target cells compared to unarmed T cells in both KKU-213A cells and A375.β6 cells. Moreover, in a five-day co-culture, A20/αCD3-armed T cells demonstrated superior cytotoxicity against KKU-213A spheroids compared to unarmed T cells. Importantly, A20/αCD3-armed T cells exhibited an increased proportion of the effector memory T cell (Tem) subset, upregulation of T cell activation markers, enhanced T cell proliferation, and increased cytolytic molecule/cytokine production, when compared to unarmed T cells in an integrin αvβ6-dependent manner. These findings support the potential of A20/αCD3-armed T cells as a novel therapeutic approach for integrin αvβ6-expressing cancers.

Granzyme B-activated IL18 potentiates αβ and γδ CAR T cell immunotherapy in a tumor-dependent manner

Interleukin (IL)18 is a potent pro-inflammatory cytokine that is activated upon caspase 1 cleavage of the latent precursor, pro-IL18. Therapeutic T cell armoring with IL18 promotes autocrine stimulation and positive modulation of the tumor microenvironment (TME). However, existing strategies are imperfect since they involve constitutive/poorly regulated activity or fail to modify the TME. Here, we have substituted the caspase 1 cleavage site within pro-IL18 with that preferred by granzyme B, yielding GzB-IL18. We demonstrate that GzB-IL18 is constitutively released but remains functionally latent unless chimeric antigen receptor (CAR) T cells are activated, owing to concomitant granzyme B release. Armoring with GzB-IL18 enhances cytolytic activity, proliferation, interferon (IFN)-γ release, and anti-tumor efficacy by a similar magnitude to constitutively active IL18. We also demonstrate that GzB-IL18 provides a highly effective armoring strategy for γδ CAR T cells, leading to enhanced metabolic fitness and significant potentiation of therapeutic activity. Finally, we show that constitutively active IL18 can unmask CAR T cell-mediated cytokine release syndrome in immunocompetent mice. By contrast, GzB-IL18 promotes anti-tumor activity and myeloid cell re-programming without inducing such toxicity. Using this stringent system, we have tightly coupled the biological activity of IL18 to the activation state of the host CAR T cell, favoring safer clinical implementation of this technology.

Impact of the Pandemic was Minor Compared to Systemic Decrease in Fidelity of Assertive Community Treatment Services- A Provincial Study in Ontario, Canada

Assertive Community Treatment (ACT) model is the gold standard in community psychiatry serving people with severe mental illness. With its outreach-based design, the pandemic has profoundly affected the operations and functioning of ACT. The Dartmouth ACT Scale (DACTS) provides a standardized comprehensive and quantitative way to evaluate ACT quality. Results could inform nature of impact and identify areas for improvement. Current online survey used DACTS during the pandemic in April-May 2021. Clinical and administrative leadership of the 80 ACT teams in Ontario, Canada cross-sectionally rated ACT quality one-year pre-Covid (2018-2019) and one-year post the start of Covid (2020-2021). The overall pre-Covid Ontario ACT DACTS fidelity was 3.65. The pandemic led to decreases in all domains of DACTS (Human Resources: -4.92%, p < 0.001, 95% CI [0.08-0.27]; Organizational Boundary: -1.03%, p < 0.013,95%CI [0.01-0.07]; and Nature of Services: -6.18%, p < 0.001, 95%CI [0.16-0.26]). These changes were accounted by expected lower face-to-face encounters, time spent with clients, reduction in psychosocial services, less interactions with hospitals and diminished workforces. The magnitude of change was modest (-3.84%, p < 0.001, 95%CI [0.09-0.19]). However, the Ontario ACT pre-Covid DACTS was substantially lower (-13.5%) when compared to that from a similar survey 15 years ago (4.22), suggestive of insidious systemic level loss of fidelity. Quantitative fidelity evaluation helped to ascertain specific pandemic impact. Changes were significant and specific, but overall relatively modest when compared to the larger system level drop over the last decade. There is both evidence for model adaptability and resilience during Covid disruption, and concerns over larger downward drift in ACT fidelity and quality.

Mucin-1-Targeted Chimeric Antigen Receptor T Cells Are Effective and Safe in Controlling Solid Tumors in Immunocompetent Host

The chimeric antigen receptor (CAR) T-cell therapy in solid epithelial tumors has been explored, however, with limited success. As much of the preclinical work has relied on xenograft models in immunocompromised animals, the immune-related efficacies and toxicities may have been missed. In this study, we engineered syngeneic murine CAR T cells targeting the tumor form of human mucin-1 (tMUC1) and tested the MUC1 CAR T cells' efficacy and toxicity in the immunocompetent human MUC1-expressing mouse models. The MUC1 CAR T cells significantly eliminated murine pancreatic and breast cancer cell lines in vitro. In vivo, MUC1 CAR T cells significantly slowed the mammary gland tumor progression in the spontaneous PyVMT×MUC1.Tg (MMT) mice, prevented lung metastasis, and prolonged survival. Most importantly, there was minimal short or long-term toxicity with acceptable levels of transient liver toxicity but no kidney toxicity. In addition, the mice did not show any signs of weight loss or other behavioral changes with the treatment. We also report that a single dose of MUC1 CAR T-cell treatment modestly reduced the pancreatic tumor burden in a syngeneic orthotopic model of pancreatic ductal adenocarcinoma given at late stage of an established tumor. Taken together, these findings suggested the further development of tMUC1-targeted CAR T cells as an effective and relatively safe treatment modality for various tMUC1-expressing solid tumors.

Engineering a Dual Specificity γδ T-Cell Receptor for Cancer Immunotherapy

γδ T-cells provide immune surveillance against cancer, straddling both innate and adaptive immunity. G115 is a clonal γδ T-cell receptor (TCR) of the Vγ9Vδ2 subtype which can confer responsiveness to phosphoantigens (PAgs) when genetically introduced into conventional αβ T-cells. Cancer immunotherapy using γδ TCR-engineered T-cells is currently under clinical evaluation. In this study, we sought to broaden the cancer specificity of the G115 γδ TCR by insertion of a tumour-binding peptide into the complementarity-determining region (CDR) three regions of the TCR δ2 chain. Peptides were selected from the foot and mouth disease virus A20 peptide which binds with high affinity and selectivity to αvβ6, an epithelial-selective integrin that is expressed by a range of solid tumours. Insertion of an A20-derived 12mer peptide achieved the best results, enabling the resulting G115 + A12 T-cells to kill both PAg and αvβ6-expressing tumour cells. Cytolytic activity of G115 + A12 T-cells against PAg-presenting K562 target cells was enhanced compared to G115 control cells, in keeping with the critical role of CDR3 δ2 length for optimal PAg recognition. Activation was accompanied by interferon (IFN)-γ release in the presence of either target antigen, providing a novel dual-specificity approach for cancer immunotherapy.

Harnessing Nanomedicine to Potentiate the Chemo-Immunotherapeutic Effects of Doxorubicin and Alendronate Co-Encapsulated in Pegylated Liposomes

Encapsulation of Doxorubicin (Dox), a potent cytotoxic agent and immunogenic cell death inducer, in pegylated (Stealth) liposomes, is well known to have major pharmacologic advantages over treatment with free Dox. Reformulation of alendronate (Ald), a potent amino-bisphosphonate, by encapsulation in pegylated liposomes, results in significant immune modulatory effects through interaction with tumor-associated macrophages and activation of a subset of gamma-delta T lymphocytes. We present here recent findings of our research work with a formulation of Dox and Ald co-encapsulated in pegylated liposomes (PLAD) and discuss its pharmacological properties vis-à-vis free Dox and the current clinical formulation of pegylated liposomal Dox. PLAD is a robust formulation with high and reproducible remote loading of Dox and high stability in plasma. Results of biodistribution studies, imaging with radionuclide-labeled liposomes, and therapeutic studies as a single agent and in combination with immune checkpoint inhibitors or gamma-delta T lymphocytes suggest that PLAD is a unique product with distinct tumor microenvironmental interactions and distinct pharmacologic properties when compared with free Dox and the clinical formulation of pegylated liposomal Dox. These results underscore the potential added value of PLAD for chemo-immunotherapy of cancer and the relevance of the co-encapsulation approach in nanomedicine.

The realities of Medical Assistance in Dying in Canada

OBJECTIVES

To examine the impact of the Canadian MAiD program and analyze its safeguards.

METHODS

A working group of physicians from diverse practice backgrounds and a legal expert, several with bioethics expertise, reviewed Canadian MAiD data and case reports. Grey literature was also considered, including fact-checked and reliable Canadian mainstream newspapers and parliamentary committee hearings considering the expansion of MAiD.

RESULTS

Several scientific studies and reviews, provincial and correctional system authorities have identified issues with MAiD practice. As well, there is a growing accumulation of narrative accounts detailing people getting MAiD due to suffering associated with a lack of access to medical, disability, and social support.

SIGNIFICANCE OF RESULTS

The Canadian MAiD regime is lacking the safeguards, data collection, and oversight necessary to protect Canadians against premature death. The authors have identified these policy gaps and used MAiD cases to illustrate these findings.

The Role and Regulation of the NKG2D/NKG2D Ligand System in Cancer

The family of human NKG2D ligands (NKG2DL) consists of eight stress-induced molecules. Over 80% of human cancers express these ligands on the surface of tumour cells and/or associated stromal elements. In mice, NKG2D deficiency increases susceptibility to some types of cancer, implicating this system in immune surveillance for malignancy. However, NKG2DL can also be shed, released via exosomes and trapped intracellularly, leading to immunosuppressive effects. Moreover, NKG2D can enhance chronic inflammatory processes which themselves can increase cancer risk and progression. Indeed, tumours commonly deploy a range of countermeasures that can neutralise or even corrupt this surveillance system, tipping the balance away from immune control towards tumour progression. Consequently, the prognostic impact of NKG2DL expression in human cancer is variable. In this review, we consider the underlying biology and regulation of the NKG2D/NKG2DL system and its expression and role in a range of cancer types. We also consider the opportunities for pharmacological modulation of NKG2DL expression while cautioning that such interventions need to be carefully calibrated according to the biology of the specific cancer type.

Chimeric Antigen Receptor (CAR) T-Cell Therapy for Patients with Lung Cancer: Current Perspectives

Immunotherapy using chimeric antigen receptor (CAR)-engineered T-cells has achieved unprecedented efficacy in selected hematological cancers. However, solid tumors such as lung cancer impose several additional challenges to the attainment of clinical success using this emerging therapeutic modality. Lung cancer is the biggest cause of cancer-related mortality worldwide, accounting for approximately 1.8 million deaths worldwide each year. Obstacles to the development of CAR T-cell immunotherapy for lung cancer include the selection of safe tumor-selective targets, accounting for the large number of candidates that have been evaluated thus far. Tumor heterogeneity is also a key hurdle, meaning that single target-based approaches are susceptible to therapeutic failure through the emergence of antigen null cancers. There is also a need to enable CAR T-cells to traffic efficiently to sites of disease, to infiltrate tumor deposits and to operate within the hostile tumor microenvironment formed by solid tumors, resisting the onset of exhaustion. Multiple immune, metabolic, physical and chemical barriers operate at the core of malignant lesions, with potential for further heterogeneity and evolution in the face of selective therapeutic pressures. Although the extraordinarily adaptable nature of lung cancers has recently been unmasked, immunotherapy using immune checkpoint blockade can achieve long-term disease control in a small number of patients, establishing clinical proof of concept that immunotherapies can control advanced lung carcinomas. This review summarizes pre-clinical CAR T-cell research that is specifically focused on lung cancer in addition to published and ongoing clinical trial activity. A number of advanced engineering strategies are also described which are designed to bridge the gap to the attainment of meaningful efficacy using genetically engineered T-cells.

Impact of COVID-19 on the lives of people with severe mental illness-front-line community psychiatry workers observation from a provincial survey of assertive community treatment teams in Ontario, Canada

Using an online survey distributed to members of the provincial organization that represents the 88 Assertive Community Treatment (ACT) and Flexible ACT teams in Ontario, Canada, this descriptive study relied on the unique vantage points and observations of the front-line community psychiatry workers who maintained contact with patients through outreach and telecommunication during the height of COVID-19. The patients who suffer from serious mental illness (SMI) were uniquely affected by COVID-19 due to the changes, reduction or shut down of many essential clinical and community support services. Thematic and quantitative analyses of the workers' observations highlighted 6 main areas of note, including significant social isolation and loneliness, clinical course deterioration and life disruption, increased hospital and ER use, police and legal contacts, and substance abuse and related deaths. There were also encouraging signs of positive adaptations in terms of independence and resilience. Reflections of these impacts and potential ameliorating approaches are further discussed.

Intratumoral pan-ErbB targeted CAR-T for head and neck squamous cell carcinoma: interim analysis of the T4 immunotherapy study

BACKGROUND

Locally advanced/recurrent head and neck squamous cell carcinoma (HNSCC) is associated with significant morbidity and mortality. To target upregulated ErbB dimer expression in this cancer, we developed an autologous CD28-based chimeric antigen receptor T-cell (CAR-T) approach named T4 immunotherapy. Patient-derived T-cells are engineered by retroviral transduction to coexpress a panErbB-specific CAR called T1E28ζ and an IL-4-responsive chimeric cytokine receptor, 4αβ, which allows IL-4-mediated enrichment of transduced cells during manufacture. These cells elicit preclinical antitumor activity against HNSCC and other carcinomas. In this trial, we used intratumoral delivery to mitigate significant clinical risk of on-target off-tumor toxicity owing to low-level ErbB expression in healthy tissues.

METHODS

We undertook a phase 1 dose-escalation 3+3 trial of intratumoral T4 immunotherapy in HNSCC (NCT01818323). CAR T-cell batches were manufactured from 40 to 130 mL of whole blood using a 2-week semiclosed process. A single CAR T-cell treatment, formulated as a fresh product in 1-4 mL of medium, was injected into one or more target lesions. Dose of CAR T-cells was escalated in 5 cohorts from 1×107-1×109 T4+ T-cells, administered without prior lymphodepletion.

RESULTS

Despite baseline lymphopenia in most enrolled subjects, the target cell dose was successfully manufactured in all cases, yielding up to 7.5 billion T-cells (67.5±11.8% transduced), without any batch failures. Treatment-related adverse events were all grade 2 or less, with no dose-limiting toxicities (Common Terminology Criteria for Adverse Events V.4.0). Frequent treatment-related adverse events were tumor swelling, pain, pyrexias, chills, and fatigue. There was no evidence of leakage of T4+ T-cells into the circulation following intratumoral delivery, and injection of radiolabeled cells demonstrated intratumoral persistence. Despite rapid progression at trial entry, stabilization of disease (Response Evaluation Criteria in Solid Tumors V.1.1) was observed in 9 of 15 subjects (60%) at 6 weeks post-CAR T-cell administration. Subsequent treatment with pembrolizumab and T-VEC oncolytic virus achieved a rapid complete clinical response in one subject, which was durable for over 3 years. Median overall survival was greater than for historical controls. Disease stabilization was associated with the administration of an immunophenotypically fitter, less exhausted, T4 CAR T-cell product.

CONCLUSIONS

These data demonstrate the safe intratumoral administration of T4 immunotherapy in advanced HNSCC.

CAR-Based Immunotherapy of Solid Tumours-A Survey of the Emerging Targets

Immunotherapy with CAR T-cells has revolutionised the treatment of B-cell and plasma cell-derived cancers. However, solid tumours present a much greater challenge for treatment using CAR-engineered immune cells. In a partner review, we have surveyed data generated in clinical trials in which patients with solid tumours that expressed any of 30 discrete targets were treated with CAR-based immunotherapy. That exercise confirms that efficacy of this approach falls well behind that seen in haematological malignancies, while significant toxic events have also been reported. Here, we consider approximately 60 additional candidates for which such clinical data are not available yet, but where pre-clinical data have provided support for their advancement to clinical evaluation as CAR target antigens.

CAR Based Immunotherapy of Solid Tumours-A Clinically Based Review of Target Antigens

Immunotherapy with CAR-engineered immune cells has transformed the management of selected haematological cancers. However, solid tumours have proven much more difficult to control using this emerging therapeutic modality. In this review, we survey the clinical impact of solid tumour CAR-based immunotherapy, focusing on specific targets across a range of disease indications Among the many candidates which have been the subject of non-clinical CAR T-cell research, clinical data are available for studies involving 30 of these targets. Here, we map out this clinical experience, highlighting challenges such as immunogenicity and on-target off-tumour toxicity, an issue that has been both unexpected and devastating in some cases. We also summarise how regional delivery and repeated dosing have been used in an effort to enhance impact and safety. Finally, we consider how emerging armouring systems and multi-targeted CAR approaches might be used to enhance tumour access and better enable discrimination between healthy and transformed cell types.

290 THE VARIABLE INDICATIVE OF PLACEMENT IN ACUTE HOSPITAL OUTPATIENT CLINICS IDENTIFIES OLDER ADULTS WHO BENEFIT FROM SPECIALIST GERIATRIC ASSESSMENT

Background

Opportunistic screening of older adults results in early detection of frailty. The Variable Indicative of Placement (VIP) is validated to identify those being admitted to hospital who may benefit from specialist geriatric assessment. VIP screening was gradually introduced throughout hospital-based outpatient clinics in April 2021. The aim of this study was to quantify patient benefit following VIP screening.

Methods

A positive VIP triggered referral for Comprehensive Geriatric Assessment (CGA). Exclusion criteria included prior CGA within a year, nursing home resident or patient declined assessment. Data was prospectively entered onto Excel by a trained administrator. Demographics, Clinical Frailty Score (CFS), modified Barthel Index (mBI) and patient interventions post CGA, between July 2021 and April 2022, were analysed using descriptive statistics.

Results

Of 168 referrals received, 52 were excluded, 53 completed and 63 await review. Thirty-five of those excluded had a prior CGA. Mean (SD) age of patients receiving CGA was 79 (7.6) years. Male:female ratio was 1:1.4. Median (SD) CFS was 6 (0.8) and median (SD) mBI was 16(3.9). There was a mean (SD) of 2.8 (1.6) targeted interventions per patient. Eighty three percent (n=43) required medication changes, 47% (n=25) bone health management, 28% (n=15) dietician, 26% (n=14) occupational therapy, 17% (n=9) public health nursing, 17% (n=9) speech and language therapy, 17% (n=9) memory assessment and 15% (n=8) physiotherapy.

Conclusion

Outpatient clinic VIP screening resulted in identification of frail older adults who benefited from CGA. The VIP should be validated in various outpatient settings.

233 COGNITIVE OUTCOMES AFTER A FIRST EPISODE OF DELIRIUM IN HOSPITAL – RESULTS FROM AN ADVANCED NURSE PRACTITIONER DELIRIUM CLINIC

Background

Cognitive outcomes for frail older adult inpatients with a first episode of Delirium are unknown. Aim: To determine cognitive outcomes of frail older inpatients after a first episode of Delirium.

Methods

Consecutive frail older inpatients with a 4AT score &gt;/= 4, without a previous history of cognitive impairment, over a 12-month period (January to December 2021) were invited for formal cognitive assessment 8-12 weeks after their delirium occurred. Collateral history, medication review, Addenbrookes (ACE III), bloods and CT brain were undertaken. Data was prospectively entered onto Excel and analysed using descriptive statistics.

Results

Fifty-one patients with a mean age of 82 years (SD=6) were referred to the Advanced Nurse Practitioner (ANP) Delirium Clinic. Median Clinical Frailty Score (CFS) was 6 with a male: female ratio of 1:2. Forty- seven percent (n=24) attended; 35 % (n-18) did not attend; 18 % (n=9) died prior to assessment. The ratio of male to female attendees was 1: 2.4. There was no difference in CFS or age between attenders and non-attenders. Thirty-three percent (n=8) of patients who attended had potentially reversible causes (high anti-cholinergic burden, folate deficiency, sleep disorder) of cognitive impairment requiring intervention. Sixty-seven percent (n=16) were diagnosed with dementia at the Delirium Clinic; 16.6% (n=4) were diagnosed with Mild Cognitive Impairment; 4% (n=1) had a resolved delirium; 8% (n=2) were referred to consultant Memory Clinic and one patient remained too unwell to assess. The median ACE III score of patients diagnosed with dementia was 54/100 (SD = 18).

Conclusion

Pro-active follow up of patients with a first episode of Delirium led to early diagnosis of dementia and mild cognitive impairment with supportive interventions. Earlier ANP intervention, during the acute phase of delirium, has been introduced in order to improve clinic attendance.

330 RISK OF MALNUTRITION AND ITS ASSOCIATION WITH FRAILTY-ASSOCIATED FACTORS IN THE OLDER PERSON

Background

The aetiology of malnutrition is multifactorial, with age a facilitating factor. It is associated with poorer physical and mental health and functional ability in frail older persons. Nutritional screening is a key domain in Comprehensive Geriatric Assessment (CGA). This study assessed the relationship between malnutrition risk and other drivers of frailty in the older person by CGA.

Methods

All patients who had a CGA completed by an Integrated Care Team for Older Persons from March 2020 to July 2021 inclusive were studied. Data was entered onto an Excel database by a trained administrator. The variables included were: age, gender, swallow screen, living alone, cognition, loneliness, Clinical Frailty Scale (CFS) score, falls history and risk of malnutrition using the Malnutrition-Screening Tool (MST). Odds ratio (OR), 95% Confidence Intervals (CI) was used to determine if there was an association between malnutrition risk and each variable in the total group.

Results

In total, 567 patients (325 female, 242 male), mean age 82yrs (SD =19), with median CFS of 6 were studied. Sixty-eight percent (n=384) reported a fall, 37.2% (n=211) had a positive swallow screen, 44% (n=251) lived alone, 35% (n=198) had positive cognitive screening, 14% (n=80) reported loneliness and 31.6% (n=179) were identified as at risk of malnutrition. A positive association was identified between risk of malnutrition and cognitive impairment (OR 1.9, 95%CI 1.2-3.1) and a reported fall (OR 2.2, 95%CI 1.4-3.5). In the population who had a fall and risk of malnutrition, the association remained in those aged ≥80yrs (OR 2.6, 95% CI 1.46 – 4.5) and female (OR 3.6, 95%CI 1.7 – 7.4).

Conclusion

The risk of malnutrition is associated with falls risk and cognitive impairment in frail older persons. Frail older persons identified by integrated care team for older persons with falls risk & cognitive impairment will be targeted for specialist dietetic intervention.

P06.08.B Radiation therapy enhances anti-tumor activity of a MET CAR T-based immunotherapy for glioblastoma

Background

Glioblastoma is the most frequent primary brain tumor with dismal prognosis after standard treatment with surgery, and chemoradiation (the Stupp protocol). After a decade of failed clinical trials, tumor-treating fields have been first to show the added benefit of improved overall survival compared to the Stupp protocol (20.9 months vs 16.0 months). However, GBM remains a devastating disease, with almost inevitable recurrence, and limited options for second-line therapy. Radiation therapy (RT), is a standard therapy option for GBM, and it is used in most GBM cases affecting tumor through induction of DNA-damage. Recently, RT has been investigated as a mediator of T cell-based therapies in the context of immunosuppressive GBM microenvironment. The findings have shown promise in combination of T cell-based therapies, such as chimeric antigen receptor (CAR) T cell therapies, in improving the tumor infiltration, and penetration with immune cells. MET is a relevant oncogene in the context of GBM, being involved in stem-like properties, radiation response and resistance․ Hence, MET appeared to be a plausible target for combination with RT. In our research, we use MET-targeting CAR T cells (MET-CAR T cells) combined with radiation, and hypothesize synergistic interaction for GBM treatment.

Material and Methods

We used adherent (2D) and stem-like (3D) human GBM cell lines with different levels of MET expression. For MET-CAR T cell generation we did retrovirus-mediated transduction of activated human T cells and sorted the CAR-positive cells. We co-cultured MET-CAR T cells with GBM cells with or without RT, and assessed the killing and cytokine production in CAR T cells.

Results

Our results indicated that 5Gy radiation combined with MET-CAR T cells increases their potential in tumor cell killing. We observed increased CAR T cells effect at lower CAR T to target cells ratios when combined with radiation, even when radiation treatment did not lead to a significant decrease in viability. This phenomenon was similar across different types of cell lines (adherent, stem-like), different levels of MET expression, and different sensitivity to CAR T cells. We investigated the underlying mechanisms via intracellular cytokine measurement. We observed the most prominent response in TNF-α-expression. We also observed an increase in Granzyme B expression in co-culture with some of the GBM cell lines, especially in CD8+ subpopulation of CAR T cells. IFN-gamma expression increased in some adherent glioma cell lines but not in stem-like cell lines.

Conclusion

In conclusion, our data demonstrates the potency of MET-CAR T cells against GBM, and increased efficiency when combined with radiation. The suggested mechanism is the increased activation of T cells in TNF-α-dependent-manner. To validate these results we are testing our setup in an orthotopic mouse GBM model.

CAR T-Cell Targeting of Macrophage Colony-Stimulating Factor Receptor

Macrophage colony-stimulating factor receptor (M-CSFR) is found in cells of the mononuclear phagocyte lineage and is aberrantly expressed in a range of tumours, in addition to tumour-associated macrophages. Consequently, a variety of cancer therapies directed against M-CSFR are under development. We set out to engineer chimeric antigen receptors (CARs) that employ the natural ligands of this receptor, namely M-CSF or interleukin (IL)-34, to achieve specificity for M-CSFR-expressing target cells. Both M-CSF and IL-34 bind to overlapping regions of M-CSFR, although affinity of IL-34 is significantly greater than that of M-CSF. Matched second- and third-generation CARs targeted using M-CSF or IL-34 were expressed in human T-cells using the SFG retroviral vector. We found that both M-CSF- and IL-34-containing CARs enable T-cells to mediate selective destruction of tumour cells that express enforced or endogenous M-CSFR, accompanied by production of both IL-2 and interferon (IFN)-γ. Although they contain an additional co-stimulatory module, third-generation CARs did not outperform second-generation CARs. M-CSF-containing CARs mediated enhanced cytokine production and cytolytic activity compared to IL-34-containing CARs. These data demonstrate the feasibility of targeting M-CSFR using ligand-based CARs and raise the possibility that the low picomolar affinity of IL-34 for M-CSFR is detrimental to CAR function.

Generation and application of TGFβ-educated human Vγ9Vδ2 T cells

Clinical trials that tested the antitumor activity of γδ T cells have been mostly unsuccessful. To address this, we expanded human Vγ9Vδ2 T cells in TGFβ1, a cytokine which enhances their viability, trafficking properties, and intrinsic antitumor activity. This protocol summarizes the production and in vitro functional characterization of TGFβ1 educated human Vγ9Vδ2 cells and highlights their compatibility with chimeric antigen receptor (CAR) engineering. We also describe in vivo testing of the antitumor activity of these CAR T cells in mice.

For complete details on the use and execution of this protocol, please refer to Beatson et al. (2021).

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TGFβ promotes viability and retards differentiation of Vγ9Vδ2 cells

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TGFβ-educated Vγ9Vδ2 cells achieve greater invasion and anticancer activity

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Specificity of these cells can be reprogrammed using chimeric antigen receptors

Generation of human parallel chimeric antigen receptor (pCAR) T cells to achieve synergistic T cell co-stimulation

Dual co-stimulation may be harnessed using parallel chimeric antigen receptors (pCARs) in which two distinct co-stimulatory units are adjacently localized on the plasma membrane. This protocol summarizes construct design, human T cell isolation, retroviral transduction, tissue culture expansion, and preclinical testing of pCAR T cells, exemplified by receptors that co-target avb6 integrin and ErbB dimers.

For complete details on the use and execution of this protocol, please refer to Muliaditan et al. (2021).

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A protocol to enable robust generation of pCAR T cells

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Effective dual co-stimulation is provided by this platform

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Sustained and enhanced antitumor activity by pCAR T cells

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Detailed in vitro and in vivo evaluation of pCAR technology

Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.

Engineering of an Avidity-Optimized CD19-Specific Parallel Chimeric Antigen Receptor That Delivers Dual CD28 and 4-1BB Co-Stimulation

Co-stimulation is critical to the function of chimeric antigen receptor (CAR) T-cells. Previously, we demonstrated that dual co-stimulation can be effectively harnessed by a parallel (p)CAR architecture in which a CD28-containing second generation CAR is co-expressed with a 4-1BB containing chimeric co-stimulatory receptor (CCR). When compared to linear CARs, pCAR-engineered T-cells elicit superior anti-tumor activity in a range of pre-clinical models. Since CD19 is the best validated clinical target for cellular immunotherapy, we evaluated a panel of CD19-specific CAR and pCAR T-cells in this study. First, we generated a panel of single chain antibody fragments (scFvs) by alanine scanning mutagenesis of the CD19-specific FMC63 scFv (V_H domain) and these were incorporated into second generation CD28+CD3ζ CARs. The resulting panel of CAR T-cells demonstrated a broad range of CD19 binding ability and avidity for CD19-expressing tumor cells. Each scFv-modified CAR was then converted into a pCAR by co-expression of an FMC63 scFv-targeted CCR with a 4-1BB endodomain. When compared to second generation CARs that contained an unmodified or mutated FMC63 scFv, each pCAR demonstrated a significant enhancement of tumor re-stimulation potential and IL-2 release, reduced exhaustion marker expression and enhanced therapeutic efficacy in mice with established Nalm-6 leukemic xenografts. These data reinforce the evidence that the pCAR platform delivers enhanced anti-tumor activity through effective provision of dual co-stimulation. Greatest anti-tumor activity was noted for intermediate avidity CAR T-cells and derived pCARs, raising the possibility that effector to target cell avidity is an important determinant of efficacy.