Depressed ability of patients with melanoma or renal cell carcinoma to generate adherent lymphokine-activated killer cells

Depicting adoptive immunotherapy for prostate cancer in an animal model with magnetic resonance imaging

Genetically modified natural killer (NK) cells that recognize tumor-associated surface antigens have recently shown promise as a novel approach for cancer immunotherapy. To determine NK cell therapy response early, a real-time, noninvasive method to quantify NK cell homing to the tumor is desirable. The purpose of this study was to evaluate if MR imaging could provide a noninvasive, in vivo diagnosis of NK cell accumulation in epithelial cell adhesion molecule (EpCAM)-positive prostate cancers in a rat xenograft model. Genetically engineered NK-92-scFv(MOC31)-ζ cells, which express a chimeric antigen receptor specific to the tumor-associated EpCAM antigen, and nontargeted NK-92 cells were labeled with superparamagnetic particles of iron-oxides (SPIO) ferumoxides. Twelve athymic rats with implanted EpCAM positive DU145 prostate cancers received intravenous injections of 1.5×10(7) SPIO labeled NK-92 and NK-92-scFv(MOC31)-ζ cells. EpCAM-positive prostate cancers demonstrated a progressive and a significant decline in contrast-to-noise-ratio data at 1 and 24 h after injection of SPIO-labeled NK-92-scFv(MOC31)-ζ cells. Conversely, tumor contrast-to-noise-ratio data did not change significantly after injection of SPIO-labeled parental NK-92 cells. Histopathology confirmed an accumulation of the genetically engineered NK-92-scFv(MOC31)-ζ cells in prostate cancers. Thus, the presence or absence of a tumor accumulation of therapeutic NK cells can be monitored with cellular MR imaging. EpCAM-directed, SPIO labeled NK-92-scFv(MOC31)-ζ cells accumulate in EpCAM-positive prostate cancers.

Expression of a CD20-specific chimeric antigen receptor enhances cytotoxic activity of NK cells and overcomes NK-resistance of lymphoma and leukemia cells

Despite the clinical success of CD20-specific antibody rituximab, malignancies of B-cell origin continue to present a major clinical challenge, in part due to an inability of the antibody to activate antibody-dependent cell-mediated cytotoxicity (ADCC) in some patients, and development of resistance in others. Expression of chimeric antigen receptors in effector cells operative in ADCC might allow to bypass insufficient activation via FcgammaRIII and other resistance mechanisms that limit natural killer (NK)-cell activity. Here we have generated genetically modified NK cells carrying a chimeric antigen receptor that consists of a CD20-specific scFv antibody fragment, via a flexible hinge region connected to the CD3zeta chain as a signaling moiety. As effector cells we employed continuously growing, clinically applicable human NK-92 cells. While activity of the retargeted NK-92 against CD20-negative targets remained unchanged, the gene modified NK cells displayed markedly enhanced cytotoxicity toward NK-sensitive CD20 expressing cells. Importantly, in contrast to parental NK-92, CD20-specific NK cells efficiently lysed CD20 expressing but otherwise NK-resistant established and primary lymphoma and leukemia cells, demonstrating that this strategy can overcome NK-cell resistance and might be suitable for the development of effective cell-based therapeutics for the treatment of B-cell malignancies.

Retargeting of natural killer–cell cytolytic activity to ErbB2-expressing cancer cells results in efficient and selective tumor cell destruction

The continuously growing natural killer (NK) cell line NK-92 is highly cytotoxic against malignant cells of various origins without affecting normal human cells. Based on this selectivity, the potential of NK-92 cells for adoptive therapy is currently being investigated in phase I clinical studies. To further enhance the antitumoral activity of NK-92 cells and expand the range of tumor entities suitable for NK-92–based therapies, here by transduction with a retroviral vector we have generated genetically modified NK-92 cells expressing a chimeric antigen receptor specific for the tumor-associated ErbB2 (HER2/neu) antigen, which is overexpressed by many tumors of epithelial origin. The chimeric antigen receptor consists of the ErbB2-specific scFv(FRP5) antibody fragment, a flexible hinge region derived from CD8, and transmembrane and intracellular regions of the CD3 ζ chain. Transduced NK-92-scFv(FRP5)-ζ cells express high levels of the fusion protein on the cell surface as determined by fluorescence-activated cell-scanning (FACS) analysis. In europium release assays, no difference in cytotoxic activity of NK-92 and NK-92-scFv(FRP5)-ζ cells toward ErbB2-negative targets was found. However, even at low effector-to-target ratios, NK-92-scFv(FRP5)-ζ cells specifically and efficiently lysed established and primary ErbB2-expressing tumor cells that were completely resistant to cytolytic activity of parental NK-92 cells. These results demonstrate that efficient retargeting of NK-92 cytotoxicity can be achieved and might allow the generation of potent cell-based therapeutics for the treatment of ErbB2-expressing malignancies.

Cellular immunotherapy of malignancies using the clonal natural killer cell line NK-92

For years activated natural killer (A-NK) cells have been explored with respect to their efficacy in anticancer therapy, but, except for some anectdotal reports, no clear clinical benefit has been shown. However, as the understanding about the interactions of NK cells and tumor cells advances, the use of A-NK cells might be revisited with more sophisticated approaches that pay tribute to mechanisms which allow tumor cells to escape immune surveillance. Here the highly cytotoxic NK cell line NK-92 seems to be an attractive alternative for use in adoptive immunotherapy, because it was shown to exhibit substantial antitumor activity against a wide range of malignancies in vitro as well as in xenografted SCID mice. NK-92 cells are characterized by an almost complete lack of killer cell immunglobulin-like receptors (KIRs) yet conserved ability to perforin and granzyme B-mediated cytolytic activity, which make them unique among the few established NK and T cell-like cell lines. NK-92 is the only natural killer cell line that has entered clinical trials. Here we discuss the current status of development of this cell line for adoptive immunotherapy (AIT) of malignancies and review our first clinical experience in patients with advanced cancer who have received repeated transfusions of irradiated NK-92 in a phase I/II trial. Also we discuss issues that address safety aspects of immunotherapy with clonal cell lines and describe further manipulations, which hold the potential of significantly improving the clinical outcome of AIT with NK-92.

Adriamycin-mediated potentiation of cytotoxicity against freshly isolated bladder cancer cells by autologous non-activated peripheral blood lymphocytes and tumor infiltrating lymphocytes

PURPOSE

Previous studies indicated that cancer patients lack functional anti-tumor cytotoxic lymphocytes. However, anti-tumor cytotoxic lymphocytes may coexist with immunoresistant tumor cells. We reasoned that anti-tumor cytotoxic activity of lymphocytes may be revealed if the tumor cells are sensitized to killing. It has been reported that adriamycin (ADR) exhibits various immunomodulating activities. In the present study, we investigate the effect of ADR on the susceptibility of freshly isolated bladder cancer cells to lysis by autologous non-activated peripheral blood lymphocytes (PBL) and tumor infiltrating lymphocytes (TIL).

MATERIALS AND METHODS

Cytotoxicity was determined by a 1-day microculture tetrazolium dye assay.

RESULTS

Treatment of ADR-resistant fresh bladder cancer cells with ADR at 0.1 microg./ml. or more for 3 hours or more enhanced their susceptibility to lysis by autologous PBL. This ADR-induced enhancement of susceptibility of fresh bladder cancer cells to lysis by PBL was also observed when lymphokine activated killer cells, purified natural killer cells and T lymphocytes were used as effector cells. Furthermore, while cytotoxicity of freshly derived TIL against autologous bladder cancer cells was minimal, significant cytotoxicity was observed with ADR-treated bladder cancer cells. The ADR analogs, epirubicin and pirarubicin, also enhanced the susceptibility of bladder cancer cells to lysis by autologous PBL. Treatment of bladder cancer cells with ADR had no effect on the expression of MHC class I on the cancer cells or the frequency of bladder cancer target cell conjugates to autologous PBL. Treatment of bladder cancer cells with ADR augmented their sensitivity to anti-Fas monoclonal antibody and tumor necrosis factor-a. Pretreatment of effector cells with ADR had no effect on their cytotoxic function.

CONCLUSIONS

These findings demonstrate that PBL and TIL in patients with bladder cancer exhibit anti-tumor cytotoxic function, but their function is not manifested due to development or acquisition of tumor cell resistance to killing. However, the resistance of bladder cancer cells to killing by cytotoxic lymphocytes is overcome if cancer cells are sensitized by subtoxic concentrations of ADR. These findings suggest that treatment of bladder cancer patients with low doses of ADR may sensitize the cancer cells to killing by autologous circulating and tumor infiltrating lymphocytes and may be a novel immunotherapeutic modality for the treatment of drug-resistant and/or immune-resistant bladder cancer.

Pretreatment serum markers and lymphocyte response to interleukin-2 therapy

Lymphocytosis is a marker of subcutaneous interleukin (IL)-2 therapy efficacy, whereas baseline elevated inflammatory indices were noticed in IL-2-resistant disease. The aim of this study was to analyse the relationship between pretreatment circulating values of IL-6, neopterin, sIL-2R, ESR and the changes in lymphocyte number in response to IL-2 administration. Twenty metastatic renal cell cancer patients were treated with subcutaneous IL-2 immunotherapy (6 000 000 IU day(-1) for 6 days per week for 4 weeks); tumour response consisted of partial response (PR) in four patients, stable disease (SD) in eight patients and progressive disease (PD) in eight patients. Abnormally high pretreatment values of each marker were found as follows: IL-6 in seven patients, neopterin in nine patients, sIL-2R in 13 patients. In response to IL-2 immunotherapy, a significantly higher mean increase in lymphocyte number and a higher percentage of patients with tumour response or stable disease were observed when pretreatment values of IL-6, neopterin and sIL-2R were within the normal range, in comparison to patients with high values for these markers. The pretreatment excess of these serum inflammatory markers seems to negatively influence both the host and tumour response to IL-2 administration, by preventing the IL-2-induced lymphocytosis and resulting in tumour progression. Further studies are requested to verify if overall survival and quality of life may depend on pretreatment host immune status and/or lymphocyte response after IL-2 administration.

The monoclonal antibody GZS-1 detects a maturation-associated antigen of human spermatozoa that is also present on the surface of human mononuclear blood cells

A monoclonal antibody (GZS-1) has been generated by fusion of mouse myeloma cells with spleen cells from BALB/c mice immunised with human sperm cells. The antibody was determined to be an IgG1. The corresponding antigen is present on the whole surface of ejaculated human spermatozoa. It is not detectable on spermatozoa of other mammalian species (rabbit, cat, dog, sheep, boar, bull, horse). In human male genital organs, immunostaining with GZS-1 is observed on sperm cells in the epididymis and the ductus deferens together with the lining epithelium of those organs. No reactivity of sperm cells or germ cell precursors in the testis has been detected. Functional tests using the antibody show a strong inhibitory effect of human sperm in the hamster egg penetration assay. Furthermore, the GZS-1 antigen is detectable on the surface of human lymphocytes and monocytes by immunogold electron microscopy and FACS analysis. By Western blotting of human sperm and seminal plasma performed under reducing conditions immunostaining was detected at 21-25, 31, 51-54, and 62 kDa. The reaction with human lymphocytes shows one major band at 62 kDa and additional bands at 31 and 54 kDa. The results suggest that the monoclonal antibody GZS-1 may recognise an antigen which is secreted from the epithelial cells of the epididymis and binds to ejaculated spermatozoa as a sperm coating antigen. This component may be involved in the capacitation of the sperm and the acrosome reaction. Molecules that are expressed both on sperm and on immunocompetent cells may be relevant for the regulation of immunological processes or for the development of the related immunological tolerance of sperm in the female reproductive tract.

Natural killer (NK) and lymphokine-activated killer (LAK) activities in a patient who recovered from cancer, and the characteristics of LAK cells generated from CD4-CD8- and CD8+ peripheral blood lymphocytes

The natural killer (NK) and lymphokine-activated killer (LAK) activities of a patient who recovered from bladder transitional cell carcinoma were determined. The patient was diagnosed in 1980 and repeated several therapies until 1986. Since 1987, he has been in a tumor-free state. Recently, very high NK and LAK activities were found. The NK activity was recognized not only against the NK-sensitive cell line K562, but also against NK-unsensitive Raji and Daudi cell lines and against autotumor cell line H41. The percentage of CD16+ in peripheral blood lymphocytes (PBL) was 52.9%, the CD8+CD16+ was 26.3%, and the CD4-CD8-CD16+ was 26.6% (17.5, 5.4 and 12.1% in healthy blood donor (control), respectively). Because the patient had large numbers of CD4-CD8- cells in the PBL, CD4-CD8- LAK were generated from them. The CD4-CD8- LAK cells exhibited extremely high killer activity, whereas the CD8+ LAK cells generated from the CD8+ cells showed a low level of killer activity. These results suggest that the tumor-free condition of this patient may be related to these high killer activities. In this patient, several cytokines were also determined, although the results were not completely interpreted.

Antimetastatic effect of immunization with liposome-encapsulated tumor cell-membrane proteins obtained from experimental tumors

Immunization of C57BL/6 mice with tumor-derived membrane-proteins encapsulated in sized liposomes (0.2 microgram/mouse) and composed by phosphatidylcholine or sphingomyelin, significantly reduced the mean values of spontaneous lung metastasis from both B16 (0.7 +/- 0.5 and 1.2 +/- 0.6, respectively) and 3LL (4.8 +/- 2.5 and 7.2 +/- 4.1, respectively) tumors, with respect to control (HEPES) groups (4.8 +/- 1.1 and 19.0 +/- 4.4, respectively). However, no significant antimetastatic effect was observed using free tumor-derived proteins (2 micrograms/mouse) or liposome vehicle alone. Specific humoral immune response after the vaccination was studied by flow cytometry of tumor cells incubated with a pooled sample from each group of immunized mice and FITC-conjugate antimouse immunoglobulins. The results showed that the highest number of positive tumor cells was identified using sera from immunized mice with sized liposomes encapsulating tumor-derived proteins whereas the immunization with the protein fraction in free form failed to induce this effect. In addition, an increased cytotoxicity towards 3LL and B16 tumor cells can also be observed when tumor cells were incubated with spleen effector cells plus specific immunosera. In conclusion, our results show that antitumor active vaccination, using sized liposomes as adjuvants, induces an antitumor host response and a significant inhibition of tumor progression.