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

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

Polyol synthesis, functionalisation, and biocompatibility studies of superparamagnetic iron oxide nanoparticles as potential MRI contrast agents

Iron oxide nanoparticles (IONPs) of low polydispersity were obtained through a simple polyol synthesis in high pressure and high temperature conditions. The control of the size and morphology of the nanoparticles was studied by varying the solvent used, the amount of iron precursor and the reaction time. Compared with conventional synthesis methods such as thermal decomposition or co-precipitation, this process yields nanoparticles with a narrow particle size distribution in a simple, reproducible and cost effective manner without the need for an inert atmosphere. For example, IONPs with a diameter of ca. 8 nm could be made in a reproducible manner and with good crystallinity as evidenced by X-ray diffraction analysis and high saturation magnetization value (84.5 emu g(-1)). The surface of the IONPs could be tailored post synthesis with two different ligands which provided functionality and stability in water and phosphate buffer saline (PBS). Their potential as a magnetic resonance imaging (MRI) contrast agent was confirmed as they exhibited high r1 and r2 relaxivities of 7.95 mM(-1) s(-1) and 185.58 mM(-1) s(-1) respectively at 1.4 T. Biocompatibility and viability of IONPs in primary human mesenchymal stem cells (hMSCs) was studied and confirmed

Tracking stem cells in tissue-engineered organs using magnetic nanoparticles

The use of human stem cells (SCs) in tissue engineering holds promise in revolutionising the treatment of numerous diseases. There is a pressing need to comprehend the distribution, movement and role of SCs once implanted onto scaffolds. Nanotechnology has provided a platform to investigate this through the development of inorganic magnetic nanoparticles (MNPs). MNPs can be used to label and track SCs by magnetic resonance imaging (MRI) since this clinically available imaging modality has high spatial resolution. In this review, we highlight recent applications of iron oxide and gadolinium based MNPs in SC labelling and MRI; and offer novel considerations for their future development

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

Autologous Cell Seeding in Tracheal Tissue Engineering

Purpose of Review: There is no consensus on the best technology to be employed for tracheal replacement. One particularly promising approach is based upon tissue engineering and involves applying autologous cells to transplantable scaffolds. Here, we present the reported pre-clinical and clinical data exploring the various options for achieving such seeding. Recent Findings: Various cell combinations, delivery strategies, and outcome measures are described. Mesenchymal stem cells (MSCs) are the most widely employed cell type in tracheal bioengineering. Airway epithelial cell luminal seeding is also widely employed, alone or in combination with other cell types. Combinations have thus far shown the greatest promise. Chondrocytes may improve mechanical outcomes in pre-clinical models, but have not been clinically tested. Rapid or pre-vascularization of scaffolds is an important consideration. Overall, there are few published objective measures of post-seeding cell viability, survival, or overall efficacy. Summary: There is no clear consensus on the optimal cell-scaffold combination and mechanisms for seeding. Systematic in vivo work is required to assess differences between tracheal grafts seeded with combinations of clinically deliverable cell types using objective outcome measures, including those for functionality and host immune response

Allogeneic Mesenchymal Stromal Cell Injection to Alleviate Ischemic Heart Failure Following Arterial Switch Operation.

Cell therapy is a promising tool to prevent and treat heart failure in congenital heart disease. We report the first case of intramyocardial injection of allogeneic mesenchymal stromal cells as rescue therapy in a neonate with ischemic heart failure following arterial switch procedure for isolated transposition of the great arteries. (Level of Difficulty: Advanced.

Evaluation of the chemical and biomechanical viscoelastic properties of decellularised tracheal scaffolds [46]

Evaluation of the chemical and biomechanical viscoelastic properties of decellularised tracheal scaffolds [46

Natural killer cells differentiated in vitro from cord blood CD34(+) cells are more advantageous for use as an immunotherapy than peripheral blood and cord blood natural killer cells

BACKGROUND AIMS: Natural killer (NK) cells have the potential to become a successful immunotherapy as they can target malignant cells without being direct effectors of graft-versus-host disease. Our group has previously shown that large numbers of functional NK cells can be differentiated in vitro from umbilical cord blood (CB) CD34(+) cells. To produce a clinically relevant and effective immunotherapy, we hypothesized that it is essential that the NK cells are able to proliferate and persist in vivo while maintaining an optimal activation status and killing capacity. METHODS: We evaluated the proliferation capacity, telomere length and terminal differentiation markers expressed by NK cells differentiated in vitro. We also determined how their cytotoxicity compared with peripheral blood (PB) NK cells and CBNK cells when targeting patient acute myeloid leukemia (AML) blasts and solid tumor cell lines. RESULTS: We found that the differentiated NK cells could respond to interleukin-2 and proliferate in vitro. Telomere length was significantly increased, whereas CD57 expression was significantly reduced compared with PBNK cells. The cytotoxicity of the differentiated NK cells was equivalent to that of the PBNK and CBNK cell controls, and priming consistently led to higher levels of killing of patient leukemic blasts and solid tumor cell lines in vitro. Interestingly, this activation step was not required to observe killing of patient AML blasts in vivo. CONCLUSION: We are able to generate NK cells from CBCD34(+) cells in high numbers, allowing for multiple infusions of highly cytotoxic NK cells that have potential to further proliferate in vivo, making them a desirable product for application as an immunotherapy in the clinic

A Phase 1 Trial of CNDO-109-Activated Natural Killer Cells in Patients with High-Risk Acute Myeloid Leukemia

Natural killer (NK) cells are an emerging immunotherapy approach to acute myeloid leukemia (AML); however, the optimal approach to activate NK cells before adoptive transfer remains unclear. Human NK cells that are primed with the CTV-1 leukemia cell line lysate CNDO-109 exhibit enhanced cytotoxicity against NK cell–resistant cell lines. To translate this finding to the clinic, CNDO-109–activated NK cells (CNDO-109-NK cells) isolated from related HLA-haploidentical donors were evaluated in a phase 1 dose-escalation trial at doses of 3 × 105 (n = 3), 1 × 106 (n = 3), and 3 × 106 (n = 6) cells/kg in patients with AML in first complete remission (CR1) at high risk for recurrence. Before CNDO-109-NK cell administration, patients were treated with lymphodepleting fludarabine/cyclophosphamide. CNDO-109-NK cells were well tolerated, and no dose-limiting toxicities were observed at the highest tested dose. The median relapse-free survival (RFS) by dose level was 105 (3 × 105), 156 (1 × 106), and 337 (3 × 106) days. Two patients remained relapse-free in post-trial follow-up, with RFS durations exceeding 42.5 months. Donor NK cell microchimerism was detected on day 7 in 10 of 12 patients, with 3 patients having evidence of donor cells on day 14 or later. This trial establishes that CNDO-109-NK cells generated from related HLA haploidentical donors, cryopreserved, and then safely administered to AML patients with transient persistence without exogenous cytokine support. Three durable complete remissions of 32.6 to 47.6+ months were observed, suggesting additional clinical investigation of CNDO-109-NK cells for patients with myeloid malignancies, alone or in combination with additional immunotherapy strategies, is warranted