A Prospective Observational Study of Adoptive Immunotherapy for Cancer Using Zoledronate-Activated Killer (ZAK) Cells - An Analysis for Patients with Incurable Pancreatic Cancer

BACKGROUND/AIM

Adoptive immunotherapy (AIT) using autologous zoledronate-activated killer (ZAK) cells has been performed for developing a novel modality of cancer treatment. In this study, data series from incurable pancreatic cancer were analyzed.

PATIENTS AND METHODS

Patients were treated with AIT using intravenous administration of ZAK cells every 3 to 4 weeks in combination with standard chemotherapy and possible clinical benefits were examined.

RESULTS

Seventy-five patients were treated. A median overall survival (OS) time of 6.7 months was achieved for all patients and 13.1 months for those treated 5 times or more, that increased to 14.6 and 18.3 months, respectively, when the previous treatment period of chemotherapy alone was included in the analysis. The disease control rate was 58.5 %. Multivariate regression analysis showed a significant positive correlation between the survival and baseline value of lymphocyte percentage in white blood cell counts (p=0.031).

CONCLUSION

The data suggest that AIT using ZAK cells in combination with chemotherapy is safe and feasible and may be effective in prolonging survival for patients with incurable pancreatic cancer. The lymphocyte percentage at baseline may be a good biomarker for predicting the survival benefit of ZAK cell AIT.

LAK cell therapy of AML: not to be lost in translation

Expanding highly cytotoxic lymphokine activated natural killer cells and cytokine induced killer T cells by Good Manufacturing Practice-quality cultures is an important step toward effective use of those killer cells to treat acute myeloid leukemia patients receiving stem cell transplantation. Elucidating how those killer cells recognize leukemia stem cells will be the next challenge.

[Examination of the patient serum presenting a CEA false high value after cancer immuno-cell therapy]

False positive elevation of carcinoembryonic antigen (CEA) was observed in a 65-year-old woman who was treated with dendritic cell therapy (DCT) and activated lymphocyte therapy (ALT) for intrahepatic cholangiocarcinoma. Three months after the initiation of these therapies, her CEA value measured by AIA (TOSOH) began to increase without any evidence of worsening of cholangiocarcinoma. CEA was measured by several different methods, and only the result measured by AIA was high, indicating the presence of a false positive phenomenon. To clarify this phenomenon, we evaluated the patient's serum precisely. Gel filtration chromatography of her serum showed that CEA was detected in the elution fraction of IgG, which was different from the reference samples. Furthermore, this peak disappeared after incubation of patient's CEA and HBR-1. The immunoglobulin absorption test revealed that CEA value was decreased only after absorption of IgG and absorption tests using HBR-1 and MAK-absorbents showed a dramatic decrease in CEA value. These findings indicated the presence of IgG type human anti-mouse antibodies (HAMA), which interfered the measurement by AIA. Although we could not identify the reason why HAMA was produced in this patient, the facts that the false positive phenomenon was observed after the initiation of DCT and ALT, and that CEA value decreased after theses therapies were discontinued, indicated that immuno-modulaton by DCT and ALT may have a close relationship to HAMA production. It was probable that DCT and ALT activated preexisting heterophile-antibody-producing cells, which stimulated HAMA production. The incidence of such false positive reaction of CEA by HAMA in patients with DCT and ALT was low, but as the number of the patient with immuno-cell therapy increases, the incidence of such phenomenon surely increases. Because HAMA reacts to all types of immunoassay, careful attention should be paid to the evaluation of laboratory findings in patients undergoing with such immuno-cell therapies.

Immunosensitization with a Bcl-2 small molecule inhibitor

Several tumor immunotherapy approaches result in a low percentage of durable responses in selected cancers. We hypothesized that the insensitivity of cancer cells to immunotherapy may be related to an anti-apoptotic cancer cell milieu, which could be pharmacologically reverted through the inhibition of antiapoptotic Bcl-2 family proteins in cancer cells. ABT-737, a small molecule inhibitor of the antiapoptotic proteins Bcl-2, Bcl-w and Bcl-x(L), was tested for the ability to increase antitumor immune responses in two tumor immunotherapy animal models. The addition of systemic therapy with ABT-737 to the immunization of BALB/c mice with tumor antigen peptide-pulsed dendritic cells (DC) resulted in a significant delay in CT26 murine colon carcinoma tumor growth and improvement in survival. However, the addition of ABT-737 to either a vaccine strategy involving priming with TRP-2 melanoma antigen peptide-pulsed DC and boosting with recombinant Listeria monocytogenes expressing the same melanoma antigen, or the adoptive transfer of TCR transgenic cells, did not result in superior antitumor activity against B16 murine melanoma. In vitro studies failed to demonstrate increased cytotoxic lytic activity when testing the combination of ABT-737 with lymphokine activated killer (LAK) cells, or the death receptor agonists Fas, TRAIL-ligand or TNF-alpha against the CT26 and B16 cell lines. In conclusion, the Bcl-2 inhibitor ABT-737 sensitized cancer cells to the antitumor effect of antigen-specific immunotherapy in a vaccine model for the CT26 colon carcinoma in vivo but not in two immunotherapy strategies against B16 melanoma.

Long-term outcome of immunotherapy for patients with refractory pancreatic cancer

BACKGROUND

Pancreatic cancer is one of the most fatal human cancers, with a 5-year survival rate of <5% . Although new chemotherapies have been used for pancreatic cancer, the outcome is still poor. Here, we retrospectively analyzed the outcome of immunotherapy in pancreatic cancer patients and revealed the potential of immunotherapy in advanced pancreatic cancer treatment.

PATIENTS AND METHODS

Seventeen pancreatic cancer patients underwent immunotherapy in the Kyushu University and the Yakuin CA Clinic. Six patients had postoperative recurrence, 11 were diagnosed as inoperable because of metastasis, 16 had prior chemotherapy and developed chemotherapy-resistant cancers, while 1 patient had no prior chemotherapy for recurrent cancer after surgical resection because of leukopenia. Immunotherapy was combined with chemotherapy in 11 patients and without chemotherapy in 6 patients. Immunotherapy was classified into two groups; combined dendritic cell (DC) vaccination and intravenous or peritoneal injection of activated lymphocytes (DC vaccine therapy), or injection of lymphokine-activated killer lymphocytes (LAK) alone (LAK therapy).

RESULTS

Immunotherapy of refractory pancreatic cancer resulted in a median survival of 9 months. Peritoneal metastasis tended to shorten the survival period. Combination immunotherapy and chemotherapy showed no obvious difference as compared to immunotherapy alone. DC vaccine therapy conferred a significantly better survival period than LAK alone.

CONCLUSION

Our results suggest that immunotherapy utilizing DC vaccination may prolong the survival of refractory pancreatic cancer patients.

Systemic interleukin-2 and adoptive transfer of lymphokine-activated killer cells improves antibody-dependent cellular cytotoxicity in patients with relapsed B-cell lymphoma treated with rituximab

PURPOSE

Murine models have shown that antibody-dependent cellular cytotoxicity (ADCC) can be improved with addition of lymphokine-activated killer (LAK) cells to monoclonal antibodies. A pilot trial of rituximab and LAK cells in patients with rituximab-refractory CD20+ lymphoma was conducted to evaluate this approach.

EXPERIMENTAL DESIGN

Ten patients received 3 million units/m2 of interleukin-2 (IL-2) i.v. qd on days 1 to 5 and leukapheresed on days 8, 9, and 10. The leukapheresis product was cultured with IL-2 for 48 h to produce LAK cells. Patients then received 375 mg/m2 i.v. rituximab and LAK cells on days 10, 11, and 12. The patients also received 3 million units/m2 of IL-2 i.v. for 5 days starting day 10. For safety purposes, the first three patients did not receive any LAK cell infusions.

RESULTS

The LAK cell infusions improved the ADCC activity of peripheral blood lymphocytes compared with pretreatment activity and prevented the decline in ADCC seen after infusion of rituximab alone. Therapy was well tolerated and the most clinically significant toxicities were fever and fatigue. Two patients achieved a partial remission and five had stable disease.

CONCLUSIONS

The results from these studies suggest that the addition of LAK cells to rituximab augments ADCC in patients with rituximab-refractory lymphoma.

Targeting of products of genes to tumor sites using adoptively transferred A-NK and T-LAK cells

Despite successes in animals, cytokine gene expression selectively in human tumors is difficult to achieve owing to lack of efficient delivery methods. Since interleukin (IL)-2-activated natural killer (A-NK) and phytohemagglutinin and IL-2 activated killer T (T-LAK) cells, as previously demonstrated, localize and accumulate in murine lung tumor metastases following adoptive transfer, we transduced them to test their ability to deliver products of genes selectively to tumors. Assessments of transduction efficiency in vitro demonstrated that adenoviral transduction consistently resulted in high (>60%) transduction rates and substantial expression of transgenes such as GFP, Red2, luciferase, beta-galactosidase and mIL-12 for at least 4 days. In vivo experiments illustrated that Ad-GFP transduced A-NK and Ad-Red2 (RFP) transduced T-LAK or mIL-12 transduced A-NK cells localized 10-50-fold more or survived significantly better than mock transduced cells, respectively, within lung metastases than in the surrounding normal lung tissue. Most importantly, mIL-12 transduced A-NK cells provided a significantly greater antitumor response than non-transduced A-NK cells. Thus, adoptive transfer of A-NK and T-LAK cells represents an efficient method for targeting products of genes to tumor sites.

Rapid and massive expansion of cord blood-derived cytokine-induced killer cells: an innovative proposal for the treatment of leukemia relapse after cord blood transplantation

We have used a standardized 21-day expansion protocol to produce cytokine-induced killer (CIK) cells starting from very small amounts of nucleated cells (approximately 15 x 10(6) cells) isolated from cord blood. Mononuclear cells are stimulated with anti CD3 (OKT3) and IFNgamma and then expanded with IL-2. Moreover, we show that washouts of cord blood units bags (at the end of the infusion) may be sufficient to yield almost 500 x 10(6) CIK by the same expansion protocol. CIK cells show strong cytotoxic activity against a variety of tumor target cell lines including B and T lymphomas and myeloid leukemias. More importantly, expanded cord blood-derived CIK cells are cytotoxic against fresh leukemic blasts and express perforin, granzyme and NKG2D molecule at high levels. The same in vitro protocol has already been used to expand CIK cells from peripheral blood of adult donors under GMP conditions and therefore these observations open up the possibility of imagining a future clinical application of leukemia relapse following cord blood transplantation with CIK cells obtained from the same cord blood unit.

Characterization of in vitro migratory properties of anti-CD19 chimeric receptor-redirected CIK cells for their potential use in B-ALL immunotherapy

OBJECTIVE

Cytokine-induced killer (CIK) cells are ex vivo expanded cells enriched in CD3(+)CD56(+) natural killer T (NKT) cells with major histocompatibility-unrestricted cytotoxicity against several tumoral targets, except B-lineage acute lymphoblastic leukemia (B-ALL). We redirected CIK cells cytotoxicity toward B-ALL with a chimeric receptor specific for the CD19 antigen and then explored if modified-CIK cells maintain the same chemotactic properties of freshly isolated NKT cells, whose trafficking machinery reflects their preferential localization into the sites of B-ALL infiltration.

MATERIAL AND METHODS

CIK cells were expanded ex vivo for 21 days and analyzed for expression of adhesion molecules and chemokine receptors regulating adhesion and homing toward leukemia-infiltrated tissues. CIK cells were then transduced with the anti-CD19-zeta-internal ribosomal entry site-green fluorescent protein retroviral vector and characterized for their cytotoxicity against B-ALL cells in a (51)Cr-release assay and for their trafficking properties, including chemotactic activity, adhesion and transendothelial migration, and metalloproteases-dependent invasion of Matrigel.

RESULTS

Similarly to freshly isolated NKT cells, CD49d and CD11a were highly expressed on CIK cells. Moreover, CIK cells expressed CXCR4, CCR6, and CCR7 (mean expression 72%, 60%, and 32%, respectively), presenting chemotactic activity toward their respective ligands. Anti-CD19 chimeric receptor-modified CIK cells became cytotoxic against B-ALL cells (mean lysis, 60%) and showed, after exposure to a CXCL12 gradient, high capacity to adhere and transmigrate through endothelial cells and to invade Matrigel.

CONCLUSION

The potential capacity to localize into leukemia-infiltrated tissues of anti-CD19 chimeric receptor-redirected CIK cells, together with their ability to efficiently kill B-ALL cells, suggests that modified-CIK cells represent a valuable tool for leukemia immunotherapy.

Tracking of green fluorescent protein (GFP)-labeled LAK cells in mice carrying B16 melanoma metastases

In adoptive immunotherapy, in vivo trafficking of adoptively transferred cells, including their accumulation at tumor sites, remains to be further investigated. Tracking of these cells by visualization is useful to clarify antitumor mechanisms and develop new modalities to enhance antitumor capacities. In the present study, an in vivo tracking study was performed using an adoptive transfer model of lymphokine-activated killer (LAK) cells induced from green mice into C57/BL6 mice with B16 melanoma metastases. Green mice are green fluorescent protein (GFP) transgenic mice originating from C57/BL6 mice. All of the tissues, except for erythrocytes and hair, express green fluorescence under excitation light. Although LAK cells in combination with IL-2 potently suppressed pulmonary metastases with survival prolongation, very few LAK cells accumulated in tumor tissues compared to those localized in the spleen, as visualized by fluorescent microscopy and quantitated by flow cytometry. The present method using transfer of green mice-derived cells into parental tumor-bearing mice is simple because there is no need for in vitro labeling and is feasible for the in vivo tracking of effector cells in an adoptive immunotherapy model.

Postoperative immunosuppression cascade and immunotherapy using lymphokine-activated killer cells for patients with esophageal cancer: possible application for compensatory anti-inflammatory response syndrome

Immunological parameters were measured in order to elucidate a postoperative immunosuppression mechanism in transthoracic esophagectomy for patients with esophageal cancer. Moreover, lymphokine-activated killer (LAK) cells were transferred just after the surgery to overcome the postoperative immunosuppression. Fifteen consecutive patients who underwent transthoracic esophagectomy were subjected to the postoperative measurement of immunological parameters. Ten patients who underwent open cholecystectomy served as controls. Heparinized venous blood was obtained pre- and postoperatively, and serum levels of cytokines IL-6 and IL-10 and immunosuppressive acidic protein (IAP) were measured. Peripheral blood lymphocytes were harvested and analyzed by flow cytometry for phenotype detection and by a mixed lymphocyte reaction for detecting concanavalin (Con)-A-induced or -non-induced suppressor activity. Another 29 consecutive patients who underwent transthoracic esophagectomy were randomly enrolled in a postoperative immunotherapy trial either with or without lymphokine-activated killer cells. It was found that, in the esophagectomy group, IL-6 and IL-10 increased postoperatively and peaked on day 1, followed by an increase in IAP, peaked again on day 4, with a profound decrease in helper and cytotoxic T-cell subsets, followed by increases in Con-A-induced (on day 7 or later) and spontaneous (on day 10) suppressor activities. These changes were minimal in the cholecystectomy group. LAK cell transfer restored the postoperative decrease in the helper and cytotoxic T-cell population, and there was a trend of reduction for postoperative remote infection such as pneumonia and surgical site infection in the LAK therapy group. Taken together, we would like to propose the existence of a postoperative immunosuppression cascade consisting of increases in cytokines and immunosuppressive proteins, decreases in helper and cytotoxic T-cell populations, and the development of suppressor T-cell activities in surgery for esophageal cancer. Postoperative adoptive transfer of LAK cells may be a novel clinical application in surgery for esophageal cancer as a means of treating this postoperative immunosuppressive condition that may be identical to the status of compensatory anti-inflammatory response syndrome (CARS).

Allogeneic cell-mediated immunotherapy at the stage of minimal residual disease following high-dose chemotherapy supported by autologous stem cell transplantation

Cumulative clinical experience suggests that immunotherapy may be an effective tool for eradicating tumor cells resistant to maximum tolerated doses of chemotherapy and radiation. Immunotherapy is much more effective when applied at the stage of minimal residual disease, especially against slowly growing tumors because development of graft-versus-leukemia, lymphoma, myeloma, or in a broader sense graft-versus-tumor effects renders immunotherapy more time consuming. Hence, eradication of rapidly growing bulky tumors may be difficult or impossible to achieve. Considering the fact that optimal immunotherapy may be accomplished in patients treated at the stage of minimal (MRD) disease, in patients with hematological malignancies and chemosensitive solid tumors a stage of MRD may be best achieved following administration of myeloablative high-dose chemotherapy or chemoradiotherapy supported by autologous stem cell transplantation (autoSCT). Taken together, immunotherapy following autoSCT may provide an ideal combination for improving the cure rate of otherwise incurable cancers, especially if tumor cells may respond to cytokine-mediated immunotherapy or cell-mediated cytokine-activated immunotherapy. Following lymphocyte depletion in the course of autoSCT, adoptive transfer of alloreactive or tumor-reactive lymphocytes may be much more effective due to the preponderance of anticancer effector cells on the one hand, and elimination or depletion of the patient's regulatory cells that may downregulate anticancer effector mechanisms.

A phase I trial of autologous cytokine-induced killer cells for the treatment of relapsed Hodgkin disease and non-Hodgkin lymphoma

We have previously reported on the ex vivo generation of cytotoxic effector cells, termed cytokine-induced killer (CIK) cells, that have both in vitro and in vivo antitumor activity in murine models. We now report on our efforts for the large-scale expansion of CIK cells and also present preliminary results from a phase I clinical trial. Nine patients with advanced Hodgkin disease (n = 7) and non-Hodgkin lymphoma (n = 2), all of whom had relapsed after an autologous transplantation, were treated with escalating doses of CIK cells (3 patients at each dose level of 1 x 10(9) , 5 x 10(9) , or 1 x 10(10) cells). The CIK cells were produced by culturing unselected cells from steady-state apheresis products with interferon gamma, OKT3, and interleukin 2. After 21 days in culture, with the addition of fresh media and interleukin 2 every 3 to 4 days, the median culture was 97% viable (range, 61%-100%), 98% CD3 + (range, 66%-99%), 76% CD8 + (range, 27%-96%), 23% CD4 + (range, 6%-78%), 20% CD3 + CD56 + (range, 8%-58%), and <1% CD16 + 56 + (range, 0.2%-7.7%). The CD3 + CD56 + cells have previously been shown to exhibit the most cytotoxic activity. The absolute number of CD3 + CD56 + cells typically expanded 290-fold (range, 3- to 4000-fold) under these culture conditions. In vitro cytotoxic activity was measured against a human B-cell tumor line (OCI-Ly8). At a 40:1 effector-target cell ratio, CIK cells killed 32% (range, 2%-69%) of the target cells. A total of 21 infusions were administered to 9 patients. The number of CIK cells infused ranged from 1.0 x 10(9) to 1.0 x 10(10) per treatment. Toxicity was minimal, and there were no immediate adverse reactions to the infusions. Two patients had partial responses, and 2 patients had stabilization of disease: 1 for more than 18 months. Considering that these were heavily pretreated patients with advanced hematologic malignancies, we believe that CIK cells expanded in this fashion may have utility for the treatment of high-risk patients with evidence of minimal residual disease after autologous transplantation.

Mycophenolate mofetil does not suppress the graft-versus-leukemia effect or the activity of lymphokine-activated killer (LAK) cells in a murine model

BACKGROUND

Graft-versus-leukemia (GVL) effect is an essential component in the course of allogeneic stem cell transplantation (SCT). However, both prevention and treatment of established graft-versus-host disease (GVHD), including with drugs such as cyclosporine, can suppress GVL effects. Mycophenolate mofetil (MMF) is becoming a standard of care in SCT recipients for better prevention of GVHD as well as for promoting stem cell engraftment.

AIMS

To evaluate the effect of MMF, an immunosuppressive drug increasingly used for prevention of GVHD, on disease recurrence following SCT in a preclinical animal model. Since GVL effects may be also induced by alloreactive natural killer (NK) cells, the goal was to investigate the effects of MMF on the activity of lymphokine-activated killer (LAK) cells.

METHODS

MMF was administered by daily intraperitoneal injection starting at day 1 post-SCT. Cytotoxic LAK activity was measured by 5-h 35S-release assay, and GVL was tested by the appearance of BCL1 leukemia in a semi-mismatched (C57BL/6 donors to [BALB/c x C57BL/6] F1 recipients) murine model.

RESULTS

A dosage regimen of 28-200 mg/kg per day MMF had no negative effect on either cytotoxic LAK activity or GVL (as measured by finding of leukemic cells in recipient spleen by PCR or the appearance of clinical leukemia with adoptive transfer).

CONCLUSIONS

These results suggest that MMF does not impair GVL effects or reduce LAK cell activity in mice.

Finding a place for tumor-specific T cells in targeted cancer therapy

A goal in cancer therapeutics is to develop targeted modalities that distinguish malignant from normal cells. T cells can discriminate diseased cells based on subtle alterations in peptides displayed in association with MHC molecules at the cell surface. Recent success using the adoptive transfer of tumor-specific T cells has fueled optimism that this approach may find a place as a targeted therapy for some human cancers.

On the road to a tumor cell vaccine: 20 years of cellular immunotherapy

Cellular immunotherapy (CI), as we now know it, began in the early 1980s with the use of lymphokine-activated killer cells (LAK) and progressed to the use of the immunologically specific, tumor-infiltrating lymphocytes (TIL). TIL were shown to be particularly effective against melanoma and it was in these trials that we learned the importance of immunologic specificity for tumor. With the identification and characterization of tumor antigens recognized by TIL, we now see the use of these antigens in various forms constituting vaccines. Investigators are using tumor antigens alone or in combination with dendritic cells (DCs), the body's most efficient and powerful antigen-presenting cell. Therapies are being delivered to many patients with different types of cancer in order to combat bulky disease, eliminate micro-metastatic disease, and provide a memory mechanism to fight tumor recurrence. This review will detail the past 18 years and present the developments that have been made in this therapy. Many believe that with continued development, immunotherapy will provide a fourth modality of cancer therapy.

Adoptive immunotherapy of cancer using activated autologous lymphocytes--current status and new strategies

After the discovery of interleukin-2 (IL-2), lymphokine-activated killer (LAK) cells, tumor-infiltrating lymphocytes (TILs), and cytotoxic T lymphocytes (CTLs) sensitized with the mixed lymphocyte-tumor culture (MLTC) system have been conducted in adoptive immunotherapy (AIT) trials during past 15 years. Although the overall response rate of tumor shrinkage was marginal (9%), locoregional administration of TILs for malignant effusions was effective (77%) for a decrease or disappearance of the effusions even in terminally-ill patients, resulting in an improvement of QOL. Recent advances for molecular understanding of antigen presentation and recognition have promoted us to enhance the efficacy of AIT by using cultured dendritic cells (DCs) for generating antigen-specific CTLs in vitro. The peptide-pulsed DC-activated killer (PDAK) cells showed tumor recognition against antigen-expressing cells, and were efficiently propagated with the IL2 plus immobilized anti-CD3 antibody (IL-2/CD3) culture system. Clinical trials using PDAK cells against patients with lung metastases are now progressed, in which peptides suitable for generating CTLs were chosen in individual patients using the method designated as host-oriented peptide evaluation (HPOE) approach. Moreover, DCs were introduced with tumor-derived RNA, which was amplified with the T7 promoter system, and then were used for stimulating lymphocytes. The tumor RNA-introduced DC-activated killer (TRiDAK) cells showed tumor-specific interferon-gamma spots even in a patient in whom we failed to generate PDAK cells using DCs and peptides, suggesting that the clinical trial of AIT using TRiDAK cells is warranted for the treatment of patients with metastatic cancer. Thus, more understanding of antigen-presentation and -recognition mechanisms and immune regulation systems may promote clinical applications of AIT to establish a novel modality of cancer treatment.

Experimental immunotherapy of mice with transplanted MC-rhabdomyosarcoma resistant to doxorubicin

AIM

To compare the sensitivity of doxorubicin (DOX) sensitive and DOX-resistant MC-rhabdomyosarcoma (MC-RMS) cells to the action of lymphokine-activated cells (LAC).

RESULTS

In vitro investigations showed that LAC received from the fraction of adherent lymphocytes possess the highest activity against DOX-resistant tumor cells, and LAC from lymphocytes of total pool--against DOX-resistant tumor cells pretreated with DOX at a low dose. Adoptive immunotherapy of MC-RMS in vivo showed the highest efficacy in the cases of LAC intratumoral injection and the one combined with intraperitoneal administration of DOX at a low dose (increase of survival time by 14% and 25%, respectively).

CONCLUSION

Adoptive in vivo therapy of DOX-resistant Mh-RMS is effective if LAC or their combination with DOX at a low dose are administered.

Allogeneic versus syngeneic killer splenocytes as effector cells for the induction of graft-versus-tumor effect

The effect of allogeneic versus syngeneic killer cells derived from normal or severe combined immunodeficiency disease (SCID) mice was evaluated for induction of antitumor reaction in a murine model of mammary carcinoma. Tumor cells of H-2d origin were injected intravenously into H-2(d/b) mice 24 hours after total body irradiation (4 Gy). On the following day, lymphokine-activated killer (LAK) splenocytes, derived from either minor (H-2d) or major (H-2b) histocompatibility complex (MHC)-mismatched parental normal mice or MHC (H-2b)-mismatched SCID mice, were given intravenously. LAK cells of H-2d normal or SCID mice, syngeneic to the tumor, were inoculated in parallel. The results show that LAK cells derived from minor histocompatibility complex-mismatched or MHC-mismatched parental normal mice improved the probability of tumor-free survival as compared with LAK cells syngeneic to the tumor cells, but they aggravated the severity of graft-versus-host disease. SCID splenocytes serving as a source of natural killer (NK) cells were expanded and activated in vitro by rIL-2 to obtain a sufficient number of DX5+ CD3- CD8- NK cells (SCID-LAK). H-2b SCID-LAK cells did not cause graft-versus-host disease and significantly delayed tumor growth compared with syngeneic H-2d SCID-LAK cells, as indicated by tumor colony assays in vitro and adoptive transfer experiments. However, the graft-versus-tumor effect was not long lasting, and treated mice finally died of tumor. Our results show an advantage of allogeneic over syngeneic cell therapy for achieving a graft-versus-tumor effect by rIL-2-activated T cells and NK cells. Periodic repetition of NK treatments may be required to achieve more durable antitumor effects.

Natural killer cells in haematopoietic stem cell transplantation

Natural killer cells represent the predominant lymphoid cell in the peripheral blood for many months after allogeneic or autologous stem cell transplant and their role in immunity to pathogens during this period is established. However, following the largely unsuccessful trials of NK and IL-2 activated NK cells for the treatment of haematological malignancies in the 1980's and 90's, their role in tumour immunology was discredited. Over the past ten years we have come to understand some of the complex regulatory pathways involved in NK cell activation and we are now in a position to capitalise upon this knowledge. This review presents our current state of understanding of NK cell regulation and highlights the role of these cells in engraftment, graft-versus-host disease, anti-leukaemia activity and post-transplant infection.

Prevention of Peritoneal Carcinomatosis from Human Gastric Cancer Cells by Adjuvant-Type Intraperitoneal Immunotherapy in a SCID Mouse Model

PURPOSE

We analyzed the effect of intraperitoneal immunotherapy in an animal model mimicking locoregional dissemination of tumor cells during resection of advanced tumors.

METHODS

We first established a tumor model with human gastric cancer cells (MKN-45) in the peritoneal cavity of CB-17-SCID mice. Three hours following the injection of tumor cells into the peritoneal cavity, mAb 17-1A alone and in combination with human LAK cells were given intraperitoneally at different dosages. The results were quantified by determining the weight of the peritoneal tumor masses.

RESULTS

After intraperitoneal administration of 17-1A mAb, a tumor reduction could be shown (median tumor mass after 10 microg mAb: 171 microg; after 100 microg: 130 microg) when compared with the control group (632 microg). Following a combined therapy with mAb and LAK cells, a statistically significant tumor reduction could be observed (after 10 microg mAb + 20-50 x 10(6) LAK cells: 80 microg; after 100 microg mAb + 20-50 x 10(6) LAK cells: 12 microg, p = 0.0005). With specific dosages of antibody and LAK cells it was even possible to achieve complete tumor clearance.

CONCLUSIONS

Intraperitoneal immunotherapy reduces the peritoneal tumor masses and can even prevent the peritoneal carcinomatosis formation.

[Phenotypical analysis of effector cells on nonspecific cancer cell therapy]

In the present study, we examined the contributions of lymphocyte subpopulations in lymphokine activated killer (LAK) activity. LAK cells prepared from peripheral blood mononuclear cells (PBMC) of healthy donors showed highly cytotoxic activities against target tumor cells. When CD16 and CD56 positive cells in LAK cells were depleted by magnetic cell sorting, their cytotoxic activities were dramatically decreased. In contrast, little change was observed by the depletion of CD3 positive cells, suggesting that CD16 and/or CD56 positive populations, but not CD3 positive populations, including natural killer (NK) cells are the major cell types involved in LAK activity. Indeed, NK-enriched LAK cells prepared by culturing PBMC with IL-2 and OK-432 showed a more potent LAK activity than conventional LAK cells and CD3-activated T cells. These results suggest that selective expansion and activation of CD16 and CD56 positive cells in LAK cells is a useful strategies to improve their anti-tumor potential in nonspecific immunotherapy, and possibly in combination therapy with other target immunotherapies as well.

[Effect of DC therapy combined with chemotherapy in advanced cancer cases]

Dendritic cells (DC) are powerful antigen-presenting cells, and have attracted attention in recent years from the viewpoint of DC vaccine therapy against cancer. However, the existence of an immunosuppressive state in cancer individuals leads to anergy and immunotolerance, which has been reported to be caused by T cell and DC immunosuppressive subsets or cytokines such as Th2, Tc2, CD4+CD25+, DC2 and IL-10 against Th1, Tc1, DC1 and IL-12. Therefore, DC therapy could be incompatible with severe chemotherapy. Conversely, there are some reports that indicate tumor specific cytotoxicity in DC therapy could be augmentedly un exposure to tumor antigen caused by apoptosis in combination radiation or chemotherapy. In this study we examined the usefulness of DC therapy combined with chemotherapy and BRM (PSK) administration by analyzing the immunocyte subsets and cytokines as well as the combination effect. The results indicate this method can be useful in advanced cancer patients.