Shinsuke Iida

Specific Recruitment of CC Chemokine Receptor 4–Positive Regulatory T Cells in Hodgkin Lymphoma Fosters Immune Privilege

Hodgkin lymphoma (HL) is characterized by the presence of a small number of tumor cells in a rich background of inflammatory cells, but the contribution of the abundant nontumor cells to HL pathogenesis is poorly understood. We showed that migratory CD4(+) cells induced by HL cells were hyporesponsive to T-cell receptor stimulation and suppressed the activation/proliferation of the effector CD4(+) T cells in an autologous setting. We further showed that HL cells in the affected lymph nodes were surrounded by a large number of lymphocytes expressing both CC chemokine receptor 4 (CCR4) and FOXP3. These findings indicate that the migratory cells induced by HL cells function as regulatory T (Treg) cells so that these cells create a favorable environment for the tumor cells to escape from host immune system. In addition, we showed that a chimeric anti-CCR4 monoclonal antibody (mAb) could deplete CCR4(+) T cells and inhibit the migration of CD4(+)CD25(+) T cells in vitro. Recognition of the importance of CCR4(+) Treg cells in the pathogenesis of HL will allow rational design of more effective treatments, such as use of an anti-CCR4 mAb, to overcome the suppressive effect of CCR4(+) Treg cells on the host immune response to tumor cells.

Clinicopathologic study of CD56 (NCAM)-positive angiocentric lymphoma occurring in sites other than the upper and lower respiratory tract.

The expression of the neural cell adhesion molecule (NCAM) (CD56, NKH-1) is a rare phenomenon in malignant lymphoma. Recently, several authors, including our group, described the clinicopathologic, phenotypic, and genotypic features of NCAM-positive tumors as a unique subgroup within a larger category of hematolymphoid malignancies. Ten cases of CD56+ angiocentric lymphoma occurring in sites other than the upper aerodigestive tract were studied for evaluating their characteristics. The disease occurred in six men and four women varying from 24 to 85 years (mean age, 53 years) who often exhibited a striking predilection for extranodal sites of involvement, such as the skin, gastrointestinal tract, and muscle, usually in the absence of peripheral lymphadenopathy. Although the cytologic appearances and immunophenotypic profile varied from case to case, these tumors often exhibited azurophilic granules, an angiocentric growth pattern, and surface CD3−, T-cell receptor (TCR) antigens−, and CD56+ phenotype without B-cell phenotype, except for a single case of CD3+, TCRα/β+, and CD56+ phenotype. Genotypic investigation exhibited germline configuration of the TCR β and γ chain genes and the immunoglobulin heavy chain gene in all five cases of surface CD3− phenotype examined, whereas the case of CD3+ phenotype showed rearrangement of TCRβ. They seem to constitute a distinct entity of the lineage spectrum spanning from natural killer (NK) cell to NK-like T cell.

CXC Chemokine Receptor 3 and CC Chemokine Receptor 4 Expression in T-Cell and NK-Cell Lymphomas with Special Reference to Clinicopathological Significance for Peripheral T-Cell Lymphoma, Unspecified

We recently reported expression of the chemokine receptors CXC chemokine receptor 3 (CXCR3) and CC chemokine receptor 4 (CCR4) in adult T-cell leukemia/lymphoma and showed a preferential expression of CCR4 and its association with an unfavorable outcome. In the present study, we extend our adult T-cell leukemia/lymphoma study to other subtypes of T- and NK-cell lymphoma, to clarify whether a characteristic chemokine receptor expression pattern is obtained for each of the subtypes defined by the WHO classification. CXCR3 and CCR4 were rarely expressed in three well-defined subtypes, precursor T-lymphoblastic lymphoma, anaplastic lymphoma kinase-positive anaplastic large cell lymphoma, and extranodal NK/T-cell lymphoma. A CXCR3-dominant expression pattern was observed in angioimmunoblastic T-cell lymphoma, while a CCR4-dominant expression pattern was observed in mycosis fungoides in transformation and in anaplastic lymphoma kinase-negative anaplastic large cell lymphoma. CXCR3 and CCR4 were heterogeneously expressed in peripheral T-cell lymphomas, unspecified (PTCLU). We next focused on PTCLU and analyzed the clinical significance of the chemokine receptors and their association with FoxP3, a hallmark of immunoregulatory T (Treg) cells. Multivariate analysis showed that CCR4 expression was an independent and significant unfavorable prognostic factor (P < 0.001). A significant correlation was found between mRNA expression of CCR4 and FoxP3, suggesting a possible association of CCR4-positive tumors with Treg cells and thereby with an immunocompromised state. Chemokine receptors may be useful not only for further characterization of the T- and NK-cell lymphomas but also in predicting clinical outcomes for patients. We suggest that a specific therapy targeting the CCR4 molecule may be developed as an alternative treatment for patients with CCR4-positive tumors.

Defucosylated humanized anti-CCR4 monoclonal antibody KW-0761 as a novel immunotherapeutic agent for adult T-cell leukemia/lymphoma.

Purpose: Adult T-cell leukemia/lymphoma (ATLL) has a very poor prognosis. We have developed the humanized defucosylated anti–CC chemokine receptor 4 (CCR4) monoclonal antibody KW-0761 as a next generation immunotherapeutic agent. The first aim of the present study was to evaluate whether the antitumor activity of KW-0761 would likely be sufficient for therapeutic clinical application against ATLL. The second aim was to fully elucidate the mechanism of antibody-dependent cellular cytotoxicity (ADCC) mediated by this defucosylated monoclonal antibody. Experimental Design: The antitumor activity of KW-0761 against ATLL cell lines was evaluated in vitro using human cells and in mice in vivo. Primary ATLL cells from 23 patients were evaluated for susceptibility to autologous ADCC with KW-0761 by two independent methods. Results: KW-0761 showed potent antitumor activity against ATLL cell lines both in vitro and in the ATLL mouse model in vivo. In addition, KW-0761 showed potent antitumor activity mediated by highly enhanced ADCC against primary ATLL cells both in vitro and ex vivo in an autologous setting. The degree of KW-0761 ADCC against primary ATLL cells in an autologous setting was mainly determined by the amount of effector natural killer cells present, but not the amount of the target molecule CCR4 on the ATLL cell surface. Conclusion: KW-0761 should be sufficiently active for therapeutic clinical application for ATLL. In addition, combination treatment strategies that augment natural killer cell activity should be promising for amplifying the effect of KW-0761. In the near future, the actual efficacy of KW-0761 will be established in pivotal clinical trials. Clin Cancer Res; 16(5); 1520–31

The CC Chemokine Receptor 4 as a Novel Specific Molecular Target for Immunotherapy in Adult T-Cell Leukemia/Lymphoma

Adult T-cell leukemia/lymphoma (ATLL) is a peripheral T-cell neoplasm with dismal prognosis, and no optimal therapy has been developed. We tested the defucosylated chimeric anti-CC chemokine receptor 4 (CCR4) monoclonal antibody, KM2760, to develop a novel immunotherapy for this refractory tumor. In the presence of peripheral blood mononuclear cells (PBMCs) from healthy adult donors, KM2760 induced CCR4-specific antibody-dependent cellular cytotoxicity (ADCC) against CCR4-positive ATLL cell lines and primary tumor cells obtained from ATLL patients. We next examined the KM2760-induced ADCC against primary ATLL cells in an autologous setting. Antibody-dependent cellular cytotoxicity mediated by autologous effector cells was generally lower than that mediated by allogeneic control effector cells. However, a robust ADCC activity was induced in some cases, which was comparable with that mediated by allogeneic effector cells. It suggests that the ATLL patients’ PBMCs retain substantial ADCC-effector function, although the optimal conditions for maximal effect have not yet been determined. In addition, we also found a high expression of FoxP3 mRNA and protein, a hallmark of regulatory T cells, in ATLL cells, indicating the possibility that ATLL cells originated from regulatory T cells. KM2760 reduced FoxP3 mRNA expression in normal PBMCs along with CCR4 mRNA by lysis of CCR4+ T cells in vitro. Our data suggest not only that the CCR4 molecule could be a suitable target for the novel antibody-based therapy for patients with ATLL but also that KM2760 may induce effective tumor immunity by reducing the number of regulatory T cells.

Defucosylated anti-CCR4 monoclonal antibody exercises potent ADCC-mediated antitumor effect in the novel tumor-bearing humanized NOD/Shi-scid, IL-2Rγnull mouse model

PurposeThere are no suitable small animal models to evaluate human antibody-dependent cellular cytotoxicity (ADCC) in vivo, due to species incompatibilities. Thus, the first aim of this study was to establish a human tumor-bearing mouse model in which human immune cells can engraft and mediate ADCC, but where the endogenous mouse immune cells cannot mediate ADCC. The second aim was to evaluate ADCC mediated in these humanized mice by the defucosylated anti-CC chemokine receptor 4 (CCR4) monoclonal antibody (mAb) which we have developed and which is now in phase I clinical trials.Experimental designNOD/Shi-scid, IL-2Rγnull (NOG) mice were the recipients of human immune cells, and CCR4-expressing Hodgkin lymphoma (HL) and cutaneous T-cell lymphoma (CTCL) cell lines were used as target tumors.ResultsHumanized mice have been established using NOG mice. The chimeric defucosylated anti-CCR4 mAb KM2760 showed potent antitumor activity mediated by robust ADCC in these humanized mice bearing the HL or CTCL cell lines. KM2760 significantly increased the number of tumor-infiltrating CD56-positive NK cells which mediate ADCC, and reduced the number of tumor-infiltrating FOXP3-positive regulatory T (Treg) cells in HL-bearing humanized mice.ConclusionsAnti-CCR4 mAb could be an ideal treatment modality for many different cancers, not only to directly kill CCR4-expressing tumor cells, but also to overcome the suppressive effect of Treg cells on the host immune response to tumor cells. In addition, using our humanized mice, we can perform the appropriate preclinical evaluation of many types of antibody based immunotherapy.

Identification of Toyocamycin, an agent cytotoxic for multiple myeloma cells, as a potent inhibitor of ER stress-induced XBP1 mRNA splicing

The IRE1α-XBP1 pathway, a key component of the endoplasmic reticulum (ER) stress response, is considered to be a critical regulator for survival of multiple myeloma (MM) cells. Therefore, the availability of small-molecule inhibitors targeting this pathway would offer a new chemotherapeutic strategy for MM. Here, we screened small-molecule inhibitors of ER stress-induced XBP1 activation, and identified toyocamycin from a culture broth of an Actinomycete strain. Toyocamycin was shown to suppress thapsigargin-, tunicamycin- and 2-deoxyglucose-induced XBP1 mRNA splicing in HeLa cells without affecting activating transcription factor 6 (ATF6) and PKR-like ER kinase (PERK) activation. Furthermore, although toyocamycin was unable to inhibit IRE1α phosphorylation, it prevented IRE1α-induced XBP1 mRNA cleavage in vitro. Thus, toyocamycin is an inhibitor of IRE1α-induced XBP1 mRNA cleavage. Toyocamycin inhibited not only ER stress-induced but also constitutive activation of XBP1 expression in MM lines as well as primary samples from patients. It showed synergistic effects with bortezomib, and induced apoptosis of MM cells including bortezomib-resistant cells at nanomolar levels in a dose-dependent manner. It also inhibited growth of xenografts in an in vivo model of human MM. Taken together, our results suggest toyocamycin as a lead compound for developing anti-MM therapy and XBP1 as an appropriate molecular target for anti-MM therapy.

Stevens–Johnson Syndrome associated with mogamulizumab treatment of adult T-cell leukemia / lymphoma

We report an adult T‐cell leukemia/lymphoma patient suffering from Stevens–Johnson Syndrome (SJS) during mogamulizumab (humanized anti‐CCR4 monoclonal antibody) treatment. There was a durable significant reduction of the CD4+CD25highFOXP3+ regulatory T (Treg) cell subset in the patients PBMC, and the affected inflamed skin almost completely lacked FOXP3‐positive cells. This implies an association between reduction of the Treg subset by mogamulizimab and occurrence of SJS. The present case should contribute not only to our understanding of human pathology resulting from therapeutic depletion of Treg cells, but also alert us to the possibility of immune‐related severe adverse events such as SJS when using mogamulizumab. We are currently conducting a clinical trial of mogamulizumab for CCR4‐negative solid cancers (UMIN000010050), specifically aiming to deplete Treg cells.

Ectopic Expression of MAFB Gene in Human Myeloma Cells Carrying (14;20)(q32;q11) Chromosomal Translocations

Chromosome 14q+, which represents a chromosomal rearrangement involving the immunoglobulin heavy chain gene (IgH) locus, is a genetic hallmark of human multiple myeloma (MM). Here, we report the identification of (14;20)(q32;qll) chromosomal translocations found in MM cells. Double color fluorescence in situ hybridization analyses pinpointed the breakpoints at the 20qll locus in two MM cell lines within a length of at most 680 kb between the KIAA0823 and MAFB gene loci. Among the transcribed sequences in the vicinity of the breakpoints, an ectopic expression of the MAFB gene, which is located at 450‐680 kb telomeric to one of the breakpoints and encodes a member of the MAF family basic region/leucine zipper transcription factor, was demonstrated to be associated with t(14;20). This finding, together with that of a previous study describing its transforming activity, suggests that the MAFB gene may be one of the targets deregulated by regulatory elements of the IgH gene as a result of t(14;20).

Rapid discovery of highly potent and selective inhibitors of histone deacetylase 8 using click chemistry to generate candidate libraries.

To find HDAC8-selective inhibitors, we designed a library of HDAC inhibitor candidates, each containing a zinc-binding group that coordinates with the active-site zinc ion, linked via a triazole moiety to a capping structure that interacts with residues on the rim of the active site. These compounds were synthesized by using click chemistry. Screening identified HDAC8-selective inhibitors including C149 (IC(50) = 0.070 μM), which was more potent than PCI-34058 (6) (IC(50) = 0.31 μM), a known HDAC8 inhibitor. Molecular modeling suggested that the phenylthiomethyl group of C149 binds to a unique hydrophobic pocket of HDAC8, and the orientation of the phenylthiomethyl and hydroxamate moieties (fixed by the triazole moiety) is important for the potency and selectivity. The inhibitors caused selective acetylation of cohesin in cells and exerted growth-inhibitory effects on T-cell lymphoma and neuroblastoma cells (GI(50) = 3-80 μM). These findings suggest that HDAC8-selective inhibitors have potential as anticancer agents.