Adaptive single-KIR+NKG2C+ NK cells expanded from select superdonors show potent missing-self reactivity and efficiently control HLA-mismatched acute myeloid leukemia

BACKGROUND

Natural killer (NK) cells hold great promise as a source for allogeneic cell therapy against hematological malignancies, including acute myeloid leukemia (AML). Current treatments are hampered by variability in NK cell subset responses, a limitation which could be circumvented by specific expansion of highly potent single killer immunoglobulin-like receptor (KIR)⁺NKG2C⁺ adaptive NK cells to maximize missing-self reactivity.

METHODS

We developed a GMP-compliant protocol to expand adaptive NK cells from cryopreserved cells derived from select third-party superdonors, that is, donors harboring large adaptive NK cell subsets with desired KIR specificities at baseline. We studied the adaptive state of the cell product (ADAPT-NK) by flow cytometry and mass cytometry as well as cellular indexing of transcriptomes and epitopes by sequencing (CITE-Seq). We investigated the functional responses of ADAPT-NK cells against a wide range of tumor target cell lines and primary AML samples using flow cytometry and IncuCyte as well as in a mouse model of AML.

RESULTS

ADAPT-NK cells were >90% pure with a homogeneous expression of a single self-HLA specific KIR and expanded a median of 470-fold. The ADAPT-NK cells largely retained their adaptive transcriptional signature with activation of effector programs without signs of exhaustion. ADAPT-NK cells showed high degranulation capacity and efficient killing of HLA-C/KIR mismatched tumor cell lines as well as primary leukemic blasts from AML patients. Finally, the expanded adaptive NK cells had preserved robust antibody-dependent cellular cytotoxicity potential and combination of ADAPT-NK cells with an anti-CD16/IL-15/anti-CD33 tri-specific engager led to near-complete killing of resistant CD45^dim blast subtypes.

CONCLUSIONS

These preclinical data demonstrate the feasibility of off-the-shelf therapy with a non-engineered, yet highly specific, NK cell population with full missing-self recognition capability.

Genetic engineering of human NK cells to express CXCR2 improves migration to renal cell carcinoma

Background

Adoptive natural killer (NK) cell transfer is being increasingly used as cancer treatment. However, clinical responses have so far been limited to patients with hematological malignancies. A potential limiting factor in patients with solid tumors is defective homing of the infused NK cells to the tumor site. Chemokines regulate the migration of leukocytes expressing corresponding chemokine receptors. Various solid tumors, including renal cell carcinoma (RCC), readily secrete ligands for the chemokine receptor CXCR2. We hypothesize that infusion of NK cells expressing high levels of the CXCR2 chemokine receptor will result in increased influx of the transferred NK cells into tumors, and improved clinical outcome in patients with cancer.

Methods

Blood and tumor biopsies from 14 primary RCC patients were assessed by flow cytometry and chemokine analysis. Primary NK cells were transduced with human CXCR2 using a retroviral system. CXCR2 receptor functionality was determined by Calcium flux and NK cell migration was evaluated in transwell assays.

Results

We detected higher concentrations of CXCR2 ligands in tumors compared with plasma of RCC patients. In addition, CXCL5 levels correlated with the intratumoral infiltration of CXCR2-positive NK cells. However, tumor-infiltrating NK cells from RCC patients expressed lower CXCR2 compared with peripheral blood NK cells. Moreover, healthy donor NK cells rapidly lost their CXCR2 expression upon in vitro culture and expansion. Genetic modification of human primary NK cells to re-express CXCR2 improved their ability to specifically migrate along a chemokine gradient of recombinant CXCR2 ligands or RCC tumor supernatants compared with controls. The enhanced trafficking resulted in increased killing of target cells. In addition, while their functionality remained unchanged compared with control NK cells, CXCR2-transduced NK cells obtained increased adhesion properties and formed more conjugates with target cells.

Conclusions

To increase the success of NK cell-based therapies of solid tumors, it is of great importance to promote their homing to the tumor site. In this study, we show that stable engineering of human primary NK cells to express a chemokine receptor thereby enhancing their migration is a promising strategy to improve anti-tumor responses following adoptive transfer of NK cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s40425-017-0275-9) contains supplementary material, which is available to authorized users.

P13: THE EFFECT OF PEGFILGRASTIM ON COMPLETE BLOOD COUNT IN COLORECTAL CANCER PATIENTS TREATED WITH FOLFOX OR FOLFIRI CHEMOTHERAPY

Purpose of Study

In both FOLFOX and FOLFIRI regimens used for colorectal cancer, the 5-FU is infused over 46 hours every 14 days. Given the 10–20% risk of neutropenic fever, these regimens may be given with pegfilgrastim support. There is evidence to support its use for 21 day cycles, but no phase III trials demonstrating its efficacy and safety for regimens given every 14 days, a potential concern, given the hypothesis that the hematopoietic stem cells mobilized by pegfilgrastim into the peripheral blood may undergo cell cycle arrest, apoptosis and death while under effect of chemotherapy. Pegfilgrastim regulates the proliferation, differentiation, and survival of the myeloid lineage. It mobilizes hematopoietic progenitor cells in the peripheral circulation, has a long half-life, and is given on day 4 of 14-day infusional 5-FU based regimens. Given the fact that cytotoxic chemotherapy is administered on day 11 after pegfilgrastim, we performed a retrospective study evaluating the correlation between decrease in complete blood count and chemotherapy administered at 11 day intervals after pegfilgrastim.

Methods Used

The medical records of colorectal cancer patients were reviewed from 2003–2013. Data collected included age, stage, ethnicity, complete blood count, chemotherapy, and use of pegfilgrastim.

Summary of Results

Data from 50 eligible charts was collected. Twenty one patients were treated with chemotherapy and pegfilgrastim, 29 patients had chemotherapy alone. Prior to chemotherapy, both groups had a mean leukocyte count of 6.6×109/L and 6.8×109/L and a mean platelet count of 313,000/mm3 and 255,000/mm3 respectively. At 9 months mean leukocyte counts were 6.3×109/L and 5.4×109/L and the mean platelet counts were 186,000/mm3 and 170,000/mm3 respectively. At 24 months, the mean leukocyte counts were 6.7×109/L and 5.7×109/L and the mean platelet counts were 220,000/mm3 and 196,000 mm3 respectively.

Conclusions

When given on day 4 of a 14 day cycle, there was no effect of pegfilgrastim on complete blood counts in this small retrospective cohort study; finding a more subtle effect would require a larger sample size.

P6: CIRCULATING MICRORNA PATTERN DEFINES A BIOLOGICALLY DISTINCT BREAST CANCER PATTERN IN BLACK (B) WOMEN RELATIVE TO ONE CCCURRING IN WHITE (W) WOMEN

Purpose of Study

Black women with triple negative breast cancer have 46% lower survival rates attributed to differences in tumor biology. We analyzed presurgical plasma microRNA of white (W) and black (B) women with TNBC enrolled in our breast ovarian tissue bank between 2004 and 2014.

Aims

Detect microRNA patterns in pre-surgical plasma of TNBC W or B Analyze differences by integrated approach to detect pathways differentially activated in the two groups.

Methods Used

Between 2004 and 2014 we investigated patterns of plasma miRNAs collected before, after surgery, during and after chemotherapy in 67 patients presenting for surgery for breast cancer (W=44 & B=44) and 25 age and race matched normal controls. Two-sample t-test was used for all 2-sample comparison and ANOVA followed by Benjamin Hochberg post-hoc test to compare the mean response between subject factors of interest. All tests were 2-tailed and results with a p<0.05 were considered statistically significant. Coremine was used to identify datasets in breast cancer microarray with emphasis on our differentially expressed circulating miRs.

Summary of Results

Mean age cancer 48 (range 35–78), control 44 (range 35–67): B patients did not express over 70% of pre-surgical plasma miRs over-expressed in the W pre-surgical plasma. Black patients had lower expression of MiRs: −16-5p, −484, −126, −150-5p, −142-3p; −30c-5p, −186-5p, 139-5p. Samples from white patients overexpressed miRs−126, −150-5p, −142-3p; −30c-5p, −186-5p, 139-5p compared to healthy controls. These miRs significantly suppressed in blacks p<0.05.

Coremine text mining suggests differentially regulated microRNA are involved in mitochondrial quality control and biogenesis.

Conclusions

Deregulation in circulating miRs between B and W patients point to pathways involved in mitochondrial fission and fusion. Aberrant mitochondria biogenesis was reported as mechanism for cancer stem cell survival and detrimental to innate immunity. Such pathways could explain the lower survival seen in black breast cancer patients.

CXCL10-induced migration of adoptively transferred human natural killer cells toward solid tumors causes regression of tumor growth in vivo

Adoptive infusion of natural killer (NK) cells is being increasingly explored as a therapy in patients with cancer, although clinical responses are thus far limited to patients with hematological malignancies. Inadequate homing of infused NK cells to the tumor site represents a key factor that may explain the poor anti-tumor effect of NK cell therapy against solid tumors. One of the major players in the regulation of lymphocyte chemotaxis is the chemokine receptor chemokine (C-X-C motif) receptor 3 (CXCR3) which is expressed on activated NK cells and induces NK cell migration toward gradients of the chemokine (C-X-C motif) ligand (CXCL9, 10 and 11). Here, we show that ex vivo expansion of human NK cells results in a tenfold increased expression of the CXCR3 receptor compared with resting NK cells (p = 0.04). Consequently, these NK cells displayed an improved migratory capacity toward solid tumors, which was dependent on tumor-derived CXCL10. In xenograft models, adoptively transferred NK cells showed increased migration toward CXCL10-transfected melanoma tumors compared with CXCL10-negative wild-type tumors, resulting in significantly reduced tumor burden and increased survival (median survival 41 vs. 32 days, p = 0.03). Furthermore, administration of interferon-gamma locally in the tumor stimulated the production of CXCL10 in subcutaneous melanoma tumors resulting in increased infiltration of adoptively transferred CXCR3-positive expanded NK cells. Our findings demonstrate the importance of CXCL10-induced chemoattraction in the anti-tumor response of adoptively transferred expanded NK cells against solid melanoma tumors.

Human anaplastic thyroid carcinoma cells are sensitive to NK cell-mediated lysis via ULBP2/5/6 and chemoattract NK cells

PURPOSE

Anaplastic thyroid carcinoma (ATC) is one of the most aggressive forms of cancer with no curative therapies available. To date, strategies to target ATC by immunotherapy have not been evaluated. We investigated whether ATC would be a suitable target for natural killer (NK) cell-based immunotherapy.

EXPERIMENTAL DESIGN

We first established seven new cell lines from ATC tumors, three from papillary thyroid carcinoma tumors and analyzed them together with eight additional ATC cell lines. Cells were analyzed for sensitivity to lysis by NK cells and their ability to chemoattract and regulate the activity of NK cells. In addition, fresh tumor samples and peripheral blood from six patients with ATC were analyzed for NK cell infiltration and phenotype.

RESULTS

We observed that ATC cell lines are sensitive to lysis by ex vivo expanded NK cells and that the lysis was abrogated upon blockade of NKG2D. Sensitivity of thyroid cancer cell lines to NK cell-mediated lysis correlated with surface expression of UL16-binding protein 2 on tumor cells. Moreover, ATC cell lines produced high levels of CXCL10 and stimulated migration of expanded NK cells and ATC tumors were enriched for NK cells expressing the cognate chemokine receptor CXCR3. However, compared with NK cells in peripheral blood, ATC tumor-derived NK cells displayed a suppressed phenotype with a downregulated expression of NKG2D. In vitro, suppression of NK cell-mediated lysis and NKG2D expression by ATC cells was restored upon neutralization of prostaglandin-E2.

CONCLUSIONS

ATC cell lines are sensitive to NK cell-mediated lysis via ULBP2/5/6 and chemoattract CXCR3-positive NK cells. Patients with ATC may benefit from NK cell-based immunotherapy.

Molecular characterization of 39 de novo sSMC: contribution to prognosis and genetic counselling, a prospective study

Small supernumerary marker chromosomes (sSMCs) are structurally abnormal chromosomes that cannot be characterized by karyotype. In many prenatal cases of de novo sSMC, the outcome of pregnancy is difficult to predict because the euchromatin content is unclear. This study aimed to determine the presence or absence of euchromatin material of 39 de novo prenatally ascertained sSMC by array-comparative genomic hybridization (array-CGH) or single nucleotide polymorphism (SNP) array. Cases were prospectively ascertained from the study of 65,000 prenatal samples [0.060%; 95% confidence interval (CI), 0.042-0.082]. Array-CGH showed that 22 markers were derived from non-acrocentric markers (56.4%) and 7 from acrocentic markers (18%). The 10 additional cases remained unidentified (25.6%), but 7 of 10 could be further identified using fluorescence in situ hybridization; 69% of de novo sSMC contained euchromatin material, 95.4% of which for non-acrocentric markers. Some sSMC containing euchromatin had a normal phenotype (31% for non-acrocentric and 75% for acrocentric markers). Statistical differences between normal and abnormal phenotypes were shown for the size of the euchromatin material (more or less than 1 Mb, p = 0.0006) and number of genes (more or less than 10, p = 0.0009). This study is the largest to date and shows the utility of array-CGH or SNP array in the detection and characterization of de novo sSMC in a prenatal context.

Abstract A15: IFN-gamma-inducible-protein-10 stimulates intratumoral infiltration of adoptively transferred human NK cells in a melanoma xenograft mouse model

Aim: In the present study, we investigated whether adoptively transferred human NK cells would migrate towards IP-10 producing melanoma tumors in a xenograft mouse model. Moreover, we assessed the effect of the chemotherapeutic agent doxorubicin in increasing the sensitivity of IFNγ-treated tumors to NK cell lysis in vitro and in vivo.

Background: Adoptive transfer of natural killer (NK) cells is being increasingly used in the treatment of cancer. However, clinical trials involving adoptive transfer of NK cells have to date been more successful against leukemia and other blood-borne cancers than against solid tumors. Several groups have reported that intratumoral infiltration of NK cells correlates with improved prognosis in patients with solid tumors. Recruitment and infiltration and of NK cells in the tumor is dependent on the production of IFN-gamma-inducible-protein-10 (IP-10) by tumor cells. Although tumor cells can be triggered to produce IP-10 by IFNγ stimulation, the expression of MHC class I is increased on tumor cells resulting in decreased sensitivity to NK cell lysis.

Results: Following activation with IL-2, human NK cells upregulated the chemokine receptor CXCR3 resulting in significantly increased migration toward recombinant IP-10, MIG and I-TAC in a transwell migration assay (p=0.03). Expanded NK cells also migrated toward melanoma tumor cells that had been stimulated with IFNγ to induce secretion of IP-10 (p&lt;0.01). In an in vivo xenograft model, an increased accumulation of adoptively infused human NK cells could be detected in subcutaneous melanoma tumors transfected with IP-10 while IP-10 negative tumors had little or no NK cell infiltration (p=0.02). Following infusion of expanded NK cells, significantly reduced tumor burden (p=0.02) and prolonged survival was observed in mice bearing IP-10 positive tumors than mice bearing IP-10 negative tumors (p=0.03). We found that in mice bearing subcutaneous melanoma tumors, intratumoral injections of IFNγ triggered IP-10 production, as confirmed by protein analysis of tumor lysates. Mice that received intravenous injections of doxorubicin prior to IFNγ-injections and adoptive transfer of NK cells had a slower tumor progression than mice that received IFNγ alone prior to NK cell transfer.

Conclusion: Secretion of IP-10 from melanoma tumors stimulates intratumoral infiltration of adoptively transferred NK cells, demonstrating the importance of IP-10/CXCR3 signaling in recruitment of NK cells to solid tumors. Intratumoral IFNγ-treatment of tumors triggers an increased local production of IP-10. Pretreatment of tumor cells with doxorubicin can offset INFγ-induced resistance to NK cell lysis in vitro and in vivo.

Citation Format: Erik Wennerberg, Veronika Kremer, Andreas Lundqvist. IFN-gamma-inducible-protein-10 stimulates intratumoral infiltration of adoptively transferred human NK cells in a melanoma xenograft mouse model. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology: Multidisciplinary Science Driving Basic and Clinical Advances; Dec 2-5, 2012; Miami, FL. Philadelphia (PA): AACR; Cancer Res 2013;73(1 Suppl):Abstract nr A15.

Application of paclitaxel in low non-cytotoxic doses supports vaccination with melanoma antigens in normal mice

Chemotherapeutic agents such as paclitaxel applied in ultra-low, non-cytotoxic doses were previously shown to stimulate dendritic cell activity and anti-tumor immune responses upon vaccination in mouse transplantable tumor models. However, the mechanisms of these alterations-termed chemoimmunomodulation or chemomodulation-are still not clear. This study investigated the effect of paclitaxel applied in ultra-low, non-cytotoxic doses on the efficiency of immunization of healthy C57BL/6 mice with the peptide derived from tyrosinase related protein (TRP)-2 as a model melanoma antigen. Using an IFNγ ELISPOT assay, it was found that administration of 1 mg paclitaxel/kg in combination with the peptide vaccination strongly increased the frequencies of TRP-2 specific spleen T-cells as compared to levels due to the vaccination alone. This was associated with a significant decrease in the levels of regulatory T-cells (T(reg)) and immature myeloid cells (known as a counterpart of myeloid derived suppressor cells [MDSC] in healthy mice). Such impairments of potential immunosuppressive cells were found to correlate with a strong increase in the amount of effector CD8+ and CD4+ T-cells in the bone marrow and spleen. Furthermore, in paclitaxel-treated mice, a significant augmentation of natural killer (NK) cell numbers in the bone marrow and their ability to produce IFNγ were observed. In addition, the level of NK-T-cells in the lymph nodes was also increased. It is suggested that paclitaxel applied in ultra-low, non-cytotoxic doses may potentially enhance the efficacy of anti-tumor vaccinations by neutralizing immunosuppressive T(reg) and MDSC populations in tumor-bearing hosts.