Anti-Vα24Jα18 TCR Antibody Tunes iNKT Cell Responses to Target and Kill CD1d-negative Tumors in an FcγRII (CD32)-dependent Manner.

Invariant natural killer T (iNKT) cells play an essential role in antitumor immunity by exerting cytotoxicity and producing massive amounts of cytokines. iNKT cells express invariant T-cell receptors (TCR) to recognize their cognate glycolipid antigens such as α-galactosylceramide (α-GalCer) presented on CD1d. We recently reported that iNKT cells recognize CD1d-negative leukemia cell line K562 in a TCR-dependent manner. However, it remains controversial how iNKT cells use TCRs to recognize and exhibit cytotoxic activity toward CD1d-negative tumors cells without CD1d restriction. Here, we report that iNKT cells exerted cytotoxicity toward K562 cells via a carried over anti-Vα24 TCR mAb from positive selection by magnetic bead sorting. We found that addition of the anti-Vα24Jα18 TCR mAb (6B11 mAb) rendered iNKT cells cytotoxic to K562 cells in an FcγRII (CD32)-dependent manner. Moreover, iNKT cells treated with 6B11 mAb became cytotoxic to other CD32+ cell lines (U937 and Daudi). In addition, iNKT cells treated with 6B11 mAb suppressed K562 cell growth in a murine xenograft model in vivo. These data suggest that anti-iNKT TCR mAb treatment of iNKT cells can be applied as a therapeutic strategy to treat CD32+ cancers such as leukemia, lymphoma, and lung cancer. SIGNIFICANCE: Our findings unveiled that iNKT cells recognize and kill CD1d-negative target tumors via the anti-iNKT TCR mAb bound to CD32 at the tumor site, thereby bridging iNKT cells and CD1d-negative tumors. These findings shed light on the therapeutic potential of anti-iNKT TCR mAbs in NKT cell-based immunotherapy to treat CD1d-negative CD32+ cancers.

Progress in Natural Killer T Cell-Based Immunotherapy for Cancer: Use of Allogeneic and Gene-Edited Cells.

Immune cell therapy has received attention in the clinical setting. However, current chimeric antigen receptor T cell therapies require individualized manufacturing based on patient cells, resulting in high costs and long processing times. Allogeneic immune cell therapy, which involves the use of immune cells from other donors, is emerging as a promising alternative that offers multiple advantages, including off-the-shelf availability, standardized manufacturing, and potentially stronger effector functions. Natural killer T (NKT) cells are a type of T cell that can be activated without being restricted by HLA, indicating their potential use in allogeneic cell immunotherapy. They exhibit cytotoxic activity against various cancer targets. However, their low frequency in blood limits their use in ex vivo amplification for treatment. This has led researchers to focus on allogeneic NKT cells as a potential treatment agent. In this study, we review the research on NKT cell-based immunotherapy and focus on the recent progress in clinical trials related to NKT cell-based immunotherapy worldwide. NKT cell-based therapy is not limited to specific cancer types and has been investigated in many ways worldwide over the past decade. Some clinical trials targeting NKT cells have shown promising results; however, the number of trials is low compared to those using T and natural killer cells. The use of allogeneic NKT cells may revolutionize the treatment of cancer and other diseases. However, further research and clinical trials are necessary to fully understand their efficacy, safety, and long-term benefits.

Targeting PD-1/PD-L1 inhibits rejection in a heterotopic tracheal allograft model of lung transplantation.

Immune checkpoint molecules such as programmed death-1 (PD-1) and programmed death ligand-1 (PD-L1) have revolutionized the field of lung cancer treatment. As part of our study, we examined the role of these proteins in acute rejection in a mouse model of heterotopic tracheal transplantation. Recipient mice were untreated (Allo group) or treated with anti-PD-L1 (aPDL1 group) or PD-L1 Fc recombinant protein (PD-L1 Fc group). A further group of C57BL/6 mice received isografts (Iso group). The occlusion rate was significantly higher in the Allo group than in the Iso group (p = 0.0075), and also higher in the aPD-L1 group (p = 0.0066) and lower in the PD-L1 Fc group (p = 0.030) than in the Allo group. PD-L1 Fc recombinant protein treatment significantly decreased interleukin-6 and interferon-γ levels and reduced the CD4+/CD8+ T cell ratio, without increasing PD-1 and T-cell immunoglobulin mucin 3 expression in CD4+ T cells. These data suggest that PD-L1 Fc recombinant protein decreases the levels of inflammatory cytokines and the proportion of CD4+ T cells without exhaustion. The PD-L1-mediated immune checkpoint mechanism was associated with rejection in the murine tracheal transplant model, suggesting a potential novel target for immunotherapy in lung transplantation.

[Cancer Immunotherapy Using Allogeneic NKT Cells].

We have developed autologous NKT cell-targeted immunotherapy for lung cancer and head and neck cancer at Chiba University. We induce α-galactosylceramide(αGalCer)-pulsed antigen-presenting cells(APCs)from patients' peripheral blood mononuclear cells(PBMCs)in vitro and give them back to the patients. We transferred them intravenously to patients with lung cancer and demonstrated the potential to improve survival time. For patients with head and neck cancer, we transferred them via the nasal submucosa with ex vivo expanded autologous NKT cells. We demonstrated an increased response rate compared with αGalCer-pulsed APCs alone. This suggested that combination therapy of αGalCer-pulsed APCs and NKT cells can increase the response rate. However, NKT cells circulate at less than 0.1% in human PBMCs. Producing enough autologous NKT cells for adoptive immunotherapy is tough. Furthermore, the immunologic function of patient-derived NKT cells can vary among patients. Because stable cell production in number and nature is essential to show effective treatment results, the development of NKT cell-targeted immunotherapy is moving forward using allogeneic NKT cells worldwide. In this circumstance, we, RIKEN and Chiba University, have been developing allogeneic induced pluripotent stem cell(iPS cell)- derived NKT cell therapy. The phase Ⅰ clinical trial of iPS cell-derived NKT cell therapy for head and neck cancer is ongoing.

Regeneration of invariant natural killer T (iNKT) cells: application of iPSC technology for iNKT cell-targeted tumor immunotherapy.

Invariant natural killer T (iNKT) cells are a subset of innate-like T cells restricted by a major histocompatibility complex (MHC) class I-like molecule, CD1d. iNKT cells express an invariant T cell receptor (TCR) encoded by Vα14 Jα18 in mice and Vα24 Jα18 in humans and are activated by recognizing glycolipid antigens, such as α-galactosylceramide (αGalCer), presented by CD1d. iNKT cells exhibit anti-tumor activity via their NK-like cytotoxicity and adjuvant activity. Although iNKT cell-targeted immunotherapy is a conceptually promising approach, we still found a technical hurdle for its clinical implementation which is mainly due to the low frequency of iNKT cells, particularly in humans. To compensate for this, we proposed to generate adequate numbers of clinically competent NKT cells from induced pluripotent stem cells (iPSCs) for cancer immunotherapy. Toward this goal, we first obtained the proof of concept (POC) for this approach in mice. We developed a technology to differentiate iPSCs into iNKT cells (iPSC-iNKT cells) and found iPSC-iNKT cells efficiently rejected a syngeneic experimental thymoma by inducing antigen-specific CD8 T cells. After achieving the POC in mice, we developed human iPSC-iNKT cells, which had a high correlation in their gene expression profiles with parental iNKT cells. Human iPSC-iNKT cells also exhibited anti-tumor activity and adjuvant activity for human NK cells in vivo. Based on this supporting evidence for the anti-tumor activity of human iPSC-iNKT cells, we began to generate good manufacturing practice (GMP)-grade iPSC-iNKT cells. As of now, the first-in-human clinical trial of iPSC-iNKT cell therapy is ongoing as a single-agent, dose-escalation study for patients with advanced head and neck cancer. Demonstration of the safety of iPSC-iNKT cell therapy may allow us to improve the strategy by further reinforcing the therapeutic activity of iPSC-iNKT, cells either by gene-editing or combinatorial use with other immune cell products such as dendritic cells. Sixteen years after the establishment of the iPSC technology, we are reaching the first checkpoint to evaluate the clinical efficacy of iPSC-derived immune cells.

CD69 Imposes Tumor-Specific CD8+ T-cell Fate in Tumor-Draining Lymph Nodes.

Tumor-specific CD8+ T cells play a pivotal role in antitumor immunity and are a key target of immunotherapeutic approaches. Intratumoral CD8+ T cells are heterogeneous; Tcf1+ stemlike CD8+ T cells give rise to their cytotoxic progeny-Tim-3+ terminally differentiated CD8+ T cells. However, where and how this differentiation process occurs has not been elucidated. We herein show that terminally differentiated CD8+ T cells can be generated within tumor-draining lymph nodes (TDLN) and that CD69 expression on tumor-specific CD8+ T cells controls its differentiation process through regulating the expression of the transcription factor TOX. In TDLNs, CD69 deficiency diminished TOX expression in tumor-specific CD8+ T cells, and consequently promoted generation of functional terminally differentiated CD8+ T cells. Anti-CD69 administration promoted the generation of terminally differentiated CD8+ T cells, and the combined use of anti-CD69 and anti-programmed cell death protein 1 (PD-1) showed an efficient antitumor effect. Thus, CD69 is an attractive target for cancer immunotherapy that synergizes with immune checkpoint blockade.

Successful Identification of a Novel Therapeutic Compound for Hepatocellular Carcinoma Through Screening of ADAM9 Inhibitors.

BACKGROUND/AIM: MHC-class I-related chain A (MICA) functions as a ligand for natural killer group D, an activating receptor on natural killer (NK) cells, and its expression correlates with the carcinogenesis and progression of hepatocellular carcinoma (HCC). Although membranous MICA (mMICA) activates NK cells, soluble forms of MICA (sMICA), shed by cleaving enzymes, such as A disintegrin and metalloprotease (ADAM) 9, suppress NK cells. Therefore, the prevention of MICA shedding through the inhibition of ADAM9 has the potential to activate cancer immunity. Although we have discovered several ADAM inhibitors, many did not sufficiently activate NK cells without being cytotoxic, and, thus, new ADAM9 inhibitor candidates are needed. MATERIALS AND METHODS: To identify possible compounds for drug development, chemical library screening (a total of 741 compounds) was conducted using a fluorescence assay. Compounds with reduced fluorescence intensity were used as hit compounds in a subsequent analysis. Their impact on sMICA and mMICA in HCC cell lines was assessed using ELISA and flow cytometry, respectively. The cytotoxicity of NK cells was also evaluated by co-culturing NK cells with HCC cells. RESULTS: CCL347, a symmetrical compound with five benzene rings, was identified as a hit compound. CCL347 significantly reduced sMICA levels in the culture medium supernatant with negligible cytotoxicity. Although mMICA was also reduced, CCL347 successfully enhanced NK cell cytotoxicity in co-cultures of NK cells and HCC cells. CONCLUSION: CCL347 has potential as a novel therapeutic drug for HCC.

Effect of Atezolizumab plus Bevacizumab in Patients with Hepatocellular Carcinoma Harboring CTNNB1 Mutation in Early Clinical Experience.

Atezolizumab plus bevacizumab (ATZ/BV) treatment is a combined immunotherapy consisting of immune checkpoint inhibitor (ICI) and anti-vascular endothelial growth factor monoclonal antibody, which has brought a major paradigm shift in the treatment of unresectable hepatocellular carcinoma (HCC). Gain-of-function mutation of CTNNB1 contributes to resistance of ICI monotherapy through the framework of non-T-cell-inflamed tumor microenvironment. However, whether CTNNB1 mutation renders resistance to ATZ/BV similar to ICI monotherapy remains to be elucidated. In this study, a liquid biopsy sample in plasma of 33 patients with HCC treated with ATZ/BV was subjected to droplet digital PCR for detecting hotspot mutations at the exon 3 of CTNNB1 locus. A total of eight patients (24.2%) exhibited at least one CTNNB1 mutation. The objective response rate (ORR) in patients with wild-type (WT) and mutant (MT) CTNNB1 was 8.0% and 12.5%, respectively, and the disease control rate (DCR) was 68.0% and 87.5%, respectively. No significant difference in both ORR and DCR has been observed between the two groups. The median progression-free survival in patients with WT and MT CTNNB1 was 6.6 and 7.6 months, respectively (not statistically significant). Similarly, no significant difference in overall survival has been observed between patients with WT and MT CTNNB1 (13.6 vs. 12.3 months). In conclusion, the treatment effect of ATZ/BV in patients with HCC with MT CTNNB1 was comparable to those patients with WT CTNNB1. These results implicate that BV added to ATZ might improve immunosuppressive tumor microenvironment caused by CTNNB1 mutation.

Antibodies against complement component C5 prevent antibody-mediated rejection after lung transplantation in murine orthotopic models with skin-graft-induced pre-sensitization.

OBJECTIVE: Antibody-mediated rejection (AMR) could induce acute or chronic graft failure during organ transplantation. Several reports have shown that anti-C5 antibodies are effective against AMR after kidney transplantation. However, few reports have assessed the efficacy of anti-C5 antibodies against AMR after lung transplantation. Therefore, this study aimed to evaluate the efficacy of this novel therapy against AMR after lung transplantation. METHODS: BALB/c and C57BL/6 mice were used as donors and recipients. One group was pre-sensitized (PS) by skin transplantation 14 days before lung transplantation. The other group was non-sensitized (NS). Orthotopic left-lung transplantation was performed in both groups. Animals were killed at 2 or 7 days after lung transplantation and evaluated for histopathology, C4d immunostaining, and serum donor-specific antibodies (DSAs) (n = 5 per group). Isograft (IS) models with C57BL/6 mice were used as controls. To evaluate the efficacy of C5 inhibition, other animals, which received similar treatments to those in the PS group, were treated with anti-C5 antibodies, cyclosporine/methylprednisolone, anti-C5 antibodies/cyclosporine/methylprednisolone, or isotype-matched irrelevant control monoclonal antibodies (n = 5 per group). RESULTS: Two days after lung transplantation, the NS group exhibited mild, localized graft-rejection features (rejection score: 0.45 ± 0.08, p = 0.107). The PS group exhibited AMR features with a significantly higher rejection score (2.29 ± 0.42, p = 0.001), C4d vascular-endothelium deposition, and substantial presence of serum DSA. On day 7 after lung transplantation, both groups showed extensive graft alveolar wall destruction, and high acute-rejection scores. Mice receiving anti-C5 antibodies or anti-C5/antibodies/cyclosporine/methylprednisolone demonstrated significantly lower acute-rejection scores (0.63 ± 0.23, p = 0.002; 0.59 ± 0.22, p = 0.001, respectively) than those receiving isotype control antibodies. CONCLUSIONS: Murine orthotopic allograft lung transplant models met the clinical diagnosis and pathogenesis classification criteria of AMR. In these models, anti-C5 antibodies suppressed AMR. Therefore, anti-C5 therapy may be effective against AMR after lung transplantation.

[The Basic Research of Antigen-antibody Reaction in Lung Transplantation].

Lung transplantation has become popular in Japan, showing better survival rate than other countries. However, the results are still not satisfactory compared with other solid organ transplantation. One of the reasons for this might be that knowledge on donor-specific antibodies or antibody-related rejection, which has been attracting attention these days, is less than that of kidney or liver transplantation. Our laboratory has continued basic research in this field using rodent lung transplantation model. We have previously shown that type V collagen is associated in chronic rejection as an autoimmune, and that oral administration of type V collagen induces tolerance. The murine chronic rejection model of the minor antigen mismatch was developed, and involvement of the humoral immunity and role of the complement activation were shown. We are now studying the effects of immune checkpoint molecules, which play a central role in the field of cancer therapy, on rejection after lung transplantation. We are also working to verify the effects of anti-complement drugs and molecular targeted drugs in the future treatment on rejection.

Complement factor B regulates cellular senescence and is associated with poor prognosis in pancreatic cancer.

BACKGROUND: The interplay between cancer cells and stromal components, including soluble mediators released from cancer cells, contributes to the progression of pancreatic ductal adenocarcinoma (PDAC). Here, we set out to identify key secreted proteins involved in PDAC progression. METHODS: We performed secretome analyses of culture media of mouse pancreatic intraepithelial neoplasia (PanIN) and PDAC cells using Stable Isotope Labeling by Amino acid in Cell culture (SILAC) with click chemistry and liquid chromatography-mass spectrometry (LC-MS/MS). The results obtained were verified in primary PDAC tissue samples and cell line models. RESULTS: Complement factor B (CFB) was identified as one of the robustly upregulated proteins, and found to exhibit elevated expression in PDAC cells compared to PanIN cells. Endogenous CFB knockdown by a specific siRNA dramatically decreased the proliferation of PDAC cells, PANC-1 and MIA PaCa-II. CFB knockdown induced increases in the number of senescence-associated-ß-galactosidase (SA-ß-gal) positive cells exhibiting p21 expression upregulation, which promotes cellular senescence with cyclinD1 accumulation. Furthermore, CFB knockdown facilitated downregulation of proliferating cell nuclear antigen and led to cell cycle arrest in the G1 phase in PDAC cells. Using immunohistochemistry, we found that high stromal CFB expression was associated with unfavorable clinical outcomes with hematogenous dissemination after surgery in human PDAC patients. Despite the presence of enriched CD8+ tumor infiltrating lymphocytes in the PDAC tumor microenvironments, patients with a high stromal CFB expression exhibited a significantly poorer prognosis compared to those with a low stromal CFB expression. Immunofluorescence staining revealed a correlation between stromal CFB expression in the tumor microenvironment and an enrichment of immunosuppressive regulatory T-cells (Tregs), myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs). We also found that high stromal CFB expression showed a positive correlation with high CD8+/Foxp3+ Tregs populations in PDAC tissues. CONCLUSIONS: Our data indicate that CFB, a key secreted protein, promotes proliferation by preventing cellular senescence and is associated with immunological tumor promotion in PDAC. These findings suggest that CFB may be a potential target for the treatment of PDAC.

CD1d expression in glioblastoma is a promising target for NKT cell-based cancer immunotherapy.

Glioblastoma is the most common and aggressive type of brain tumor with high recurrence and fatality rates. Although various therapeutic strategies have been explored, there is currently no effective treatment for glioblastoma. Recently, the number of immunotherapeutic strategies has been tested for malignant brain tumors. Invariant natural killer T (iNKT) cells play an important role in anti-tumor immunity. To address if iNKT cells can target glioblastoma to exert anti-tumor activity, we assessed the expression of CD1d, an antigen-presenting molecule for iNKT cells, on glioblastoma cells. Glioblastoma cells from 10 of 15 patients expressed CD1d, and CD1d-positive glioblastoma cells pulsed with glycolipid ligand induced iNKT cell-mediated cytotoxicity in vitro. Although CD1d expression was low on glioblastoma stem-like cells, retinoic acid, which is the most common differentiating agent, upregulated CD1d expression in these cells and induced iNKT cell-mediated cytotoxicity. Moreover, intracranial administration of human iNKT cells induced tumor regression of CD1d-positive glioblastoma in orthotopic xenografts in NOD/Shi-scid IL-2RγKO (NOG) mice. Thus, CD1d expression represents a novel target for NKT cell-based immunotherapy for glioblastoma patients.

[Application of iPS Cell-Derived NKT Cells to Cancer Immunotherapy].

NKT cells are innate lymphocytes that express an invariant T cell receptor. Since activated NKT cells exert strong anti-tumor responses, NKT cells have been intensively studied for the purpose of their application to cancer immunotherapeutic approaches. Although human peripheral blood contained a very low fraction of NKT cells, and decreased number of NKT cells was also demonstrated in cancer-bearing patients, peripheral blood NKT cells can be activated by ligand-pulsed antigen presenting cells, and can produce a large amount of interferon-γ upon activation. The clinical trials of adoptive transfer of autologous NKT cells were already performed in patients with non-small cell lung cancer, and with head and neck cancer at Chiba University to show its effectiveness and limitation. Meanwhile, RIKEN reported NKT cell regeneration using iPS cell technology in mice, and subsequently established a protocol for regenerating NKT cells from human peripheral blood NKT cells using iPS cell technology. It was confirmed that the iPS cell-derived NKT cells (iPS-NKT) have sufficient expansion c apacity and potent direct and indirect cytotoxic activity in the humanized mice models, which suggests their therapeutic competence. We are currently planning an investigator-initiated clinical trial of allogeneic iPS-NKT cell therapy for head and neck cancer.

Essential Role for CD30-Transglutaminase 2 Axis in Memory Th1 and Th17 Cell Generation.

Memory helper T (Th) cells are crucial for secondary immune responses against infectious microorganisms but also drive the pathogenesis of chronic inflammatory diseases. Therefore, it is of fundamental importance to understand how memory T cells are generated. However, the molecular mechanisms governing memory Th cell generation remain incompletely understood. Here, we identified CD30 as a molecule heterogeneously expressed on effector Th1 and Th17 cells, and CD30hi effector Th1 and Th17 cells preferentially generated memory Th1 and Th17 cells. We found that CD30 mediated signal induced Transglutaminase-2 (TG2) expression, and that the TG2 expression in effector Th cells is essential for memory Th cell generation. In fact, Cd30-deficiency resulted in the impaired generation of memory Th1 and Th17 cells, which can be rescued by overexpression of TG2. Furthermore, transglutaminase-2 (Tgm2)-deficient CD4 T cells failed to become memory Th cells. As a result, T cells from Tgm2-deficient mice displayed impaired antigen-specific antibody production and attenuated Th17-mediated allergic responses. Our data indicate that CD30-induced TG2 expression in effector Th cells is essential for the generation of memory Th1 and Th17 cells, and that CD30 can be a marker for precursors of memory Th1 and Th17 cells.

A phase I study of loco-regional immunotherapy by transbronchial injection of α-galactosylceramide-pulsed antigen presenting cells in patients with lung cancer.

We conducted a phase I study of the trans-bronchial injection of α-galactosylceramide (αGalCer)-pulsed antigen presenting cells (APCs) to evaluate their safety, immune responses, and anti-tumor activities. Patients with advanced or recurrent non-small cell lung cancer (NSCLC) refractory to standard treatments were eligible. αGalCer-pulsed APCs were administered intratumorally or intranodally by bronchoscopy. Twenty-one patients were enrolled in this study. No severe adverse events related to the cell therapy were observed during this study in any patient. After αGalCer-pulsed APCs were administrated, increased iNKT cell numbers were observed in PBMCs from eight cases, and IFN-γ producing cells were increased in the peripheral blood of 10 cases. Regarding clinical responses, one case exhibited a partial response and eight were classified as stable disease. In the tumor microenvironment, IFN-γ expression was upregulated after treatment in partial response or stable disease cases and TGF-ß was upregulated in progressive disease cases.

Activated invariant natural killer T cells directly recognize leukemia cells in a CD1d-independent manner.

Invariant natural killer T (iNKT) cells are innate-like CD1d-restricted T cells that express the invariant T cell receptor (TCR) composed of Vα24 and Vß11 in humans. iNKT cells specifically recognize glycolipid antigens such as α-galactosylceramide (αGalCer) presented by CD1d. iNKT cells show direct cytotoxicity toward CD1d-positive tumor cells, especially when CD1d presents glycolipid antigens. However, iNKT cell recognition of CD1d-negative tumor cells is unknown, and direct cytotoxicity of iNKT cells toward CD1d-negative tumor cells remains controversial. Here, we demonstrate that activated iNKT cells recognize leukemia cells in a CD1d-independent manner, however still in a TCR-mediated way. iNKT cells degranulated and released Th1 cytokines toward CD1d-negative leukemia cells (K562, HL-60, REH) as well as αGalCer-loaded CD1d-positive Jurkat cells. The CD1d-independent cytotoxicity was enhanced by natural killer cell-activating receptors such as NKG2D, 2B4, DNAM-1, LFA-1 and CD2, but iNKT cells did not depend on these receptors for the recognition of CD1d-negative leukemia cells. In contrast, TCR was essential for CD1d-independent recognition and cytotoxicity. iNKT cells degranulated toward patient-derived leukemia cells independently of CD1d expression. iNKT cells targeted myeloid malignancies more than acute lymphoblastic leukemia. These findings reveal a novel anti-tumor mechanism of iNKT cells in targeting CD1d-negative tumor cells and indicate the potential of iNKT cells for clinical application to treat leukemia independently of CD1d.

Phase II study of α-galactosylceramide-pulsed antigen-presenting cells in patients with advanced or recurrent non-small cell lung cancer.

BACKGROUND: Invariant natural killer T (iNKT) cells produce copious amounts of cytokines in response to specific glycolipid antigens such as α-galactosylceramide (αGalCer) presented by CD1d-expressing antigen-presenting cells (APCs), thus orchestrating other immune cells to fight tumors. Because of their ability to induce strong antitumor responses activated by αGalCer, iNKT cells have been studied for their application in cancer immunotherapy. In our previous phase I/II trial in non-small cell lung cancer (NSCLC) patients who had completed the standard treatment, we showed a relatively long median survival time without severe treatment-related adverse events. Based on these results, we performed a phase II trial to evaluate clinical responses, safety profiles and immune responses as a second-line treatment for advanced NSCLC. METHODS: Patients with advanced or recurrent NSCLC refractory to first-line chemotherapy were eligible. αGalCer-pulsed APCs were intravenously administered four times. Overall survival time was evaluated as the primary endpoint. The safety profile and immune responses after APC injection were also monitored. This study was an open label, single-arm, phase II clinical trial performed at Chiba University Hospital, Japan. RESULTS: Thirty-five patients were enrolled in this study, of which 32 (91.4%) completed the trial. No severe adverse events related to the treatment were observed. The estimated median survival time of the 35 cases was 21.9 months (95% CI, 14.8 to 26.0). One case (2.9%) showed a partial response, 14 cases (40.0%) remained as stable disease, and 19 cases (54.3%) were evaluated as progressive disease. The geometric mean number of iNKT cells in all cases was significantly decreased and the mean numbers of natural killer (NK) cells, interferon-γ-producing cells in response to αGalCer, and effector CD8+ T cells were significantly increased after the administration of αGalCer-pulsed APCs. CONCLUSIONS: The intravenous administration of αGalCer-pulsed APCs was well-tolerated and was accompanied by prolonged overall survival. These results are encouraging and warrant further evaluation in a randomized phase III trial to demonstrate the survival benefit of this immunotherapy. TRIAL REGISTRATION NUMBER: UMIN000007321.

Immunological features of a lung cancer patient achieving an objective response with anti-programmed death-1 blockade therapy.

The role of immune checkpoint inhibitors in metastatic lung cancer has been established in recent years and the pretherapeutic profiles of the tumor microenvironment in responders have been increasingly reported. The role of salvage surgery and the immune profiles of the posttherapeutic specimens in patients achieving an objective response have rarely been studied. We report a case of metastatic lung cancer treated by anti-programmed death-1 Ab followed by surgical resection. The immune status of the tumor was assessed, showing germinal center formation, memory B cell infiltration, and a high frequency of interferon gamma -secreting T cells.

Regulatory T cells induce CD4- NKT cell anergy and suppress NKT cell cytotoxic function.

BACKGROUND: Due to the strong tumoricidal activities of activated natural killer T (NKT) cells, invariant NKT cell-based immunotherapy has shown promising clinical efficacy. However, suppressive factors, such as regulatory T cells (Tregs), may be obstacles in the use of NKT cell-based cancer immunotherapy for advanced cancer patients. Here, we investigated the suppressive effects of Tregs on NKT cells and the underlying mechanisms with the aim to improve the antitumor activities of NKT cells. METHODS: Peripheral blood samples were obtained from healthy donors, patients with benign tumors, and patients with head and neck squamous cell carcinoma (HNSCC). NKT cells, induced with α-galactosylceramide (α-GalCer), and monocyte-derived dendritic cells (DCs) were co-cultured with naïve CD4+ T cell-derived Tregs to investigate the mechanism of the Treg suppressive effect on NKT cell cytotoxic function. The functions and phenotypes of NKT cells were evaluated with flow cytometry and cytometric bead array. RESULTS: Treg suppression on NKT cell function required cell-to-cell contact and was mediated via impaired DC maturation. NKT cells cultured under Treg-enriched conditions showed a decrease in CD4- NKT cell frequency, which exert strong tumoricidal responsiveness upon α-GalCer stimulation. The same results were observed in HNSCC patients with significantly increased effector Tregs. CONCLUSION: Tregs exert suppressive effects on NKT cell tumoricidal function by inducing more CD4- NKT cell anergy and less CD4+ NKT cell anergy. Both Treg depletion and NKT cell recovery from the anergy state may be important for improving the clinical efficacy of NKT cell-based immunotherapy in patients with advanced cancers.

Soluble factors derived from neuroblastoma cell lines suppress dendritic cell differentiation and activation.

Dendritic cells (DC) play a key role in the initiation of both antitumor immunity and immunological tolerance. It has been demonstrated that exposure to soluble factors produced by tumor cells modulates DC functions and induces tolerogenic DC differentiation. In this study, we investigated the effects of neuroblastoma cell line-derived soluble factors on DC differentiation. Monocytes isolated from healthy volunteers were incubated with interleukin (IL)-4 and granulocyte-macrophage colony-stimulating factor in the presence of culture supernatants from neuroblastoma cell lines. The culture supernatants from neuroblastoma cell lines, such as NLF and GOTO, partially blocked both downregulation of CD14 and upregulation of CD1a, and dramatically decreased IL-12 and tumor necrosis factor (TNF)-α production from mature DC, while no effect of SH-SY5Y cell supernatant was noted. In addition, IL-6 and IL-10 production from monocytes was increased by the supernatants of NLF and GOTO cells at 24 hours after incubation. Furthermore, we evaluated DC functions through stimulation of invariant natural killer T (iNKT) cells. α-Galactosylceramide-pulsed DC co-cultured with supernatants of NLF cells were unable to sufficiently stimulate iNKT cells. The decreased ability of iNKT cells to produce interferon (IFN)-γ after stimulation with neuroblastoma cell line supernatant-cultured DC was reversed by addition of IL-12. CD40 expression and IL-12 production in NLF-sup-treated DC were increased by addition of exogenous IFN-γ. These results indicate that tolerogenic DC are induced in the neuroblastoma tumor microenvironment and attenuate the antitumor effects of iNKT cells. Interactions between iNKT cells and αGalCer-pulsed DC have the potential to restore the immunosuppression of tolerogenic DC through IFN-γ production.