Killers at the crossroads: The use of innate immune cells in adoptive cellular therapy of cancer

Adoptive cell therapy (ACT) is an approach to cancer treatment that involves the use of antitumor immune cells to target residual disease in patients after completion of chemo/radiotherapy. ACT has several advantages compared with other approaches in cancer immunotherapy, including the ability to specifically expand effector cells in vitro before selection for adoptive transfer, as well as the opportunity for host manipulation in order to enhance the ability of transferred cells to recognize and kill established tumors. One of the main challenges to the success of ACT in cancer clinical trials is the identification and generation of antitumor effector cells with high avidity for tumor recognition. Natural killer (NK) cells, cytokine‐induced killers and natural killer T cells are key innate or innate‐like effector cells in cancer immunosurveillance that act at the interface between innate and adaptive immunity, to have a greater influence over immune responses to cancer. In this review, we discuss recent studies that highlight their potential in cancer therapy and summarize clinical trials using these effector immune cells in adoptive cellular therapy for the treatment of cancer

T-cell receptor gene-modified cells: past promises, present methodologies and future challenges

Immunotherapy constitutes an exciting and rapidly evolving field, and the demonstration that genetically modified T-cell receptors (TCRs) can be used to produce T-lymphocyte populations of desired specificity offers new opportunities for antigen-specific T-cell therapy. Overall, TCR-modified T cells have the ability to target a wide variety of self and non–self targets through the normal biology of a T cell. Although major histocompatibility complex (MHC)–restricted and dependent on co-receptors, genetically engineered TCRs still present a number of characteristics that ensure they are an important alternative strategy to chimeric antigen receptors (CARs), and high-affinity TCRs can now be successfully engineered with the potential to enhance therapeutic efficacy while minimizing adverse events. This review will focus on the main characteristics of TCR gene-modified cells, their potential clinical application and promise to the field of adoptive cell transfer (ACT), basic manufacturing procedures and characterization protocols and overall challenges that need to be overcome so that redirection of TCR specificity may be successfully translated into clinical practice, beyond early-phase clinical trials

The expanding role of the clinical haematologist in the new world of advanced therapy medicinal products

Advanced therapy medicinal products (ATMPs) represent the current pinnacle of 'patient-specific medicines' and will change the nature of medicine in the near future. They fall into three categories; somatic cell-therapy products, gene therapy products and cells or tissues for regenerative medicine, which are termed 'tissue engineered' products. The term also incorporates 'combination products' where a human cell or tissue is combined with a medical device. Plainly, many of these new medicines share similarities with conventional haematological stem cell transplant products and donor lymphocyte infusions as well as solid organ grafts and yet ATMPs are regulated as medicines and their development has remained predominantly in academic settings and within specialist centres. However, with the advent of commercialisation of dendritic cell vaccines, chimeric antigen receptor (CAR)-T cells and genetically modified autologous haematopoietic stem cells to cure single gene-defects in β-thalassaemia and haemophilia, the widespread availability of these therapies needs to be accommodated. Uniquely to ATMPs, the patient or an allogeneic donor is regularly part of the manufacturing process. All of the examples given above require procurement of blood, bone marrow or an apheresate from a patient as a starting material for manufacture. This can only occur in a clinical facility licensed for the procurement of human cells for therapeutic use and this is likely to fall to haematology departments, either as stem cell transplant programmes or as blood transfusion departments, to provide under a contract with the company that will manufacture and supply the final medicine. The resource implications associated with this can impact on all haematology departments, not just stem cell transplant units, and should not be under-estimated

Tumor-Primed NK Cells: Waiting for the Green Light.

The functional impairment of natural killer (NK) cells has been frequently reported in cancer studies. As one of the central components of host anti-tumor immunity, NK cells exert cellular cytotoxicity against tumor cells, and secrete a cytokine milieu to inhibit tumor progression and enable the recruitment of other immune cells to the tumor site. The unlocking of the full functional potential of NK cells requires successful progression through discrete activation stages that are tightly regulated by a complex array of signaling molecules. Target cell susceptibility to NK cell-mediated killing is dependent on the intensity and specific combination of ligand expression for NK cell receptors. Tumor cells utilize numerous strategies for evading NK cells, including the downregulation of important NK cell-activating ligands. Here, we review key studies on NK cell activation requirements, and argue, based on our findings from NK cell-tumor interactions, that the altered characteristics of tumor-associated NK cells are indicative of unmet signaling requirements for full NK cell activation, rather than NK cell dysfunction in cancer

GMP compliant isolation of mucosal epithelial cells and fibroblasts from biopsy samples for clinical tissue engineering

Engineered epithelial cell sheets for clinical replacement of non-functional upper aerodigestive tract mucosa are regulated as medicinal products and should be manufactured to the standards of good manufacturing practice (GMP). The current gold standard for growth of epithelial cells for research utilises growth arrested murine 3T3 J2 feeder layers, which are not available for use as a GMP compliant raw material. Using porcine mucosal tissue, we demonstrate a new method for obtaining and growing non-keratinised squamous epithelial cells and fibroblast cells from a single biopsy, replacing the 3T3 J2 with a growth arrested primary fibroblast feeder layer and using pooled Human Platelet lysate (HPL) as the media serum supplement to replace foetal bovine serum (FBS). The initial isolation of the cells was semi-automated using an Octodissociator and the resultant cell suspension cryopreservation for future use. When compared to the gold standard of 3T3 J2 and FBS containing medium there was no reduction in growth, viability, stem cell population or ability to differentiate to mature epithelial cells. Furthermore, this method was replicated with Human buccal tissue, providing cells of sufficient quality and number to create a tissue engineered sheet

Caspase 8 activation independent of Fas (CD95/APO-1) signaling may mediate killing of B-chronic lymphocytic leukemia cells by cytotoxic drugs or gamma radiation.

Ligation of the cell-surface Fas molecule by its ligand (Fas-L) or agonistic anti-Fas monoclonal antibodies results in the cleavage and activation of the cysteine protease procaspase 8 followed by the activation of procaspase 3 and by apoptosis. In some leukemia cell lines, cytotoxic drugs induce expression of Fas-L, which may contribute to cell killing through the ligation of Fas. The involvement of Fas, Fas-L, and caspase 8 was studied in the killing of B-cell chronic lymphocytic leukemia (B-CLL) cells by chlorambucil, fludarabine, or gamma radiation. Spontaneous apoptosis was observed at 24-hour incubation, with additional apoptosis induced by each of the cytotoxic treatments. Although Fas mRNA expression was elevated after exposure to chlorambucil, fludarabine, or gamma radiation, Fas protein levels only increased after irradiation. Therefore, Fas expression may be regulated by multiple mechanisms that allow the translation of Fas mRNA only in response to restricted cytotoxic stimuli. None of the cytotoxic stimuli studied here induced Fas-L expression. An agonistic anti-Fas monoclonal antibody (CH-11) did not significantly augment apoptosis induction by any of the death stimuli. A Fas-blocking antibody (ZB4) did not inhibit spontaneous, chlorambucil-, fludarabine-, or radiation-induced apoptosis. However, procaspase 8 processing was induced by all cytotoxic stimuli. These data suggest that the Fas/Fas-L signaling system does not play a major role in the induction of apoptosis in B-CLL cells treated with cytotoxic drugs or radiation. However, Fas-independent activation of caspase 8 may play a crucial role in the regulation of apoptosis in these cells

Geldanamycin and herbimycin A induce apoptotic killing of B chronic lymphocytic leukemia cells and augment the cells' sensitivity to cytotoxic drugs.

We studied the actions of geldanamycin (GA) and herbimycin A (HMA), inhibitors of the chaperone proteins Hsp90 and GRP94, on B chronic lymphocytic leukemia (CLL) cells in vitro. Both drugs induced apoptosis of the majority of CLL isolates studied. Whereas exposure to 4-hour pulses of 30 to 100 nM GA killed normal B lymphocytes and CLL cells with similar dose responses, T lymphocytes from healthy donors as well as those present in the CLL isolates were relatively resistant. GA, but not HMA, showed a modest cytoprotective effect toward CD34+ hematopoietic progenitors from normal bone marrow. The ability of bone marrow progenitors to form hematopoietic colonies was unaffected by pulse exposures to GA. Both GA and HMA synergized with chlorambucil and fludarabine in killing a subset of CLL isolates. GA- and HMA-induced apoptosis was preceded by the up-regulation of the stress-responsive chaperones Hsp70 and BiP. Both ansamycins also resulted in down-regulation of Akt protein kinase, a modulator of cell survival. The relative resistance of T lymphocytes and of CD34+ bone marrow progenitors to GA coupled with its ability to induce apoptosis following brief exposures and to synergize with cytotoxic drugs warrant further investigation of ansamycins as potential therapeutic agents in CLL

Cryopreservation of human mesenchymal stromal cells expressing TRAIL for human anti-cancer therapy

Background aims Mesenchymal stromal cells (MSCs) are being extensively researched for cell therapy and tissue engineering. We have engineered MSCs to express the pro-apoptotic protein tumor necrosis factor–related apoptosis inducing ligand (TRAIL) and are currently preparing this genetically modified cell therapy for a phase 1/2a clinical trial in patients with metastatic lung cancer. To do this, we need to prepare a cryopreserved allogeneic MSCTRAIL cell bank for further expansion before patient delivery. The effects of cryopreservation on a genetically modified cell therapy product have not been clearly determined. Methods We tested different concentrations of dimethyl sulfoxide (DMSO) added to the human serum albumin ZENALB 4.5 and measured post-thaw cell viability, proliferation ability and differentiation characteristics. In addition, we examined the homing ability, TRAIL expression and cancer cell–killing capacities of cryopreserved genetically modified MSCs compared with fresh, continually cultured cells. Results We demonstrated that the post-thaw viability of MSCs in 5% DMSO (v/v) with 95% ZENALB 4.5 (v/v) is 85.7 ± 0.4%, which is comparable to that in conventional freezing media. We show that cryopreservation does not affect the long-term expression of TRAIL and that cryopreserved TRAIL-expressing MSCs exhibit similar levels of homing and, importantly, retain their potency in triggering cancer cell death. Conclusions This study shows that cryopreservation is unlikely to affect the therapeutic properties of MSCTRAIL and supports the generation of a cryopreserved master cell bank

Intracoronary platelet and monocyte activation status within platelet-monocyte complexes are determinants of inflammation in ST elevation myocardial infarction1

INTRODUCTION: Platelet Monocyte Complexes (PMCs) are commonly expressed in coronary artery disease but their pathologic significance in ST elevation myocardial infarction (STEMI) is unclear. This study evaluates the relationship between locally activated PMCs and intracoronary inflammation in stable and unstable coronary disease. MATERIAL AND METHODS: Micro catheter aspirated blood samples of 15 STEMI and 7 stable angina patients are collected from the coronary artery (CA), aorta (AO) and right atrium (RA). Samples are labelled with monoclonal antibodies and prepared for flow cytometry. CD 14 and CD 61 double positive cells are identified as PMC. P-selectin expression is identified by additional CD62P positivity and TF expression by additional CD142 positivity. Plasma TNF-alpha and IL-6 are measured using ELISA and CRP is measured in plasma using a high sensitivity automated microparticle enhanced latex turbidimetric immunoassay. RESULTS: No site-specific difference is seen in overall PMC expression in STEMI or stable angina. Surface P-selectin expression in STEMI [median (IQR)] is significantly higher in CA [35.01 (23.15-56.99)] compared with AO [15.99 (10.3-18.85)] or RA [14.02 (10.42-26.08)] (p = 0.003). Intracoronary PMC correlates significantly with intracoronary TNF-alpha (r = 0.87, p = 0.001) and intracoronary IL-6 (r = 0.76, p = 0.03). Bound monocytes within P-selectin positive and tissue factor positive complexes correlate positively with intracoronary TNF-alpha (r = 0.81, p = 0.008 & r = 0.80, p = 0.009 respectively) and IL-6 (r = 0.54, p = 0.16 & r = 0.71, p = 0.05 respectively). No such correlation is observed in the peripheral circulation of STEMI and stable angina patients. CONCLUSION: Inflammation is not attributable to PMC formation per se. However, increased intracoronary P-selectin expression by activated platelets and tissue factor expression by activated monocytes within the complexes are determinants of local intracoronary inflammatory burden in STEMI

Two-Stage Priming of Allogeneic Natural Killer Cells for the Treatment of Patients with Acute Myeloid Leukemia: A Phase I Trial

Human Natural Killer (NK) cells require at least two signals to trigger tumor cell lysis. Absence of ligands providing either signal 1 or 2 provides NK resistance. We manufactured a lysate of a tumour cell line which provides signal 1 to resting NK cells without signal 2. The tumor-primed NK cells (TpNK) lyse NK resistant Acute Myeloid Leukemia (AML) blasts expressing signal 2 ligands. We conducted a clinical trial to determine the toxicity of TpNK cell infusions from haploidentical donors. 15 patients with high risk AML were screened, 13 enrolled and 7 patients treated. The remaining 6 either failed to respond to re-induction chemotherapy or the donor refused to undergo peripheral blood apheresis. The conditioning consisted of fludarabine and total body irradiation. This was the first UK trial of a cell therapy regulated as a medicine. The complexity of Good Clinical Practice compliance was underestimated and led to failures requiring retrospective independent data review. The lessons learned are an important aspect of this report. There was no evidence of infusional toxicity. Profound myelosuppression was seen in the majority (median neutrophil recovery day 55). At six months follow-up, three patients treated in Complete Remission (CR) remained in remission, one patient infused in Partial Remission had achieved CR1, two had relapsed and one had died. One year post-treatment one patient remained in CR. Four patients remained in CR after treatment for longer than their most recent previous CR. During the 2 year follow-up six of seven patients died; median overall survival was 400 days post infusion (range 141–910). This is the first clinical trial of an NK therapy in the absence of IL-2 or other cytokine support. The HLA-mismatched NK cells survived and expanded in vivo without on-going host immunosuppression and appeared to exert an anti-leukemia effect in 4/7 patients treated