Cross-linking of CD40 using anti-CD40 antibody, 5C11, has different effects on XG2 multiple myeloma cells

The engineered agonistic anti-CD40 antibody potentiates the antitumor effects of β-glucan by resetting TAMs

Anti-CD40 antibodies (Abs) have been shown to induce antitumor T-cell responses. We reported that the engineered agonistic anti-CD40 Ab (5C11, IgG4 isotype) recognized human CD40 antigen expressed on a human B lymphoblastoid cell line as well as on splenic cells isolated from humanized CD40 mice. Of note, a single high dosage of 5C11 was able to prohibit tumor growth in parallel with an increase in the population of infiltrated CD8+ T cells. Furthermore, the antitumor effects of 5C11 were enhanced in the presence of β-glucan along with an increase in the population of infiltrated CD8+ T cells. In addition, the numbers of CD86+ TAMs and neutrophils were elevated in the combination of 5C11 and β-glucan compared with either 5C11 or β-glucan alone. Furthermore, the abundance of Faecalibaculum, one of the probiotics critical for tumor suppression, was obviously increased in the combination of 5C11 and β-glucan-treated mice. These data reveal a novel mechanism of tumor suppression upon the combination treatment of 5C11 and β-glucan and propose that the combination treatment of agonistic anti-human CD40 antibody 5C11 and β-glucan could be a promising therapeutic strategy for cancer patients.

Multiple Myeloma: What Do We Do About Immunodeficiency?

Multiple myeloma (MM) is an incurable hematological malignancy. Immunodeficiency results in the incapability of immunity to eradicate both tumor cells and pathogens. Immunotherapies along with antibiotics and other anti-infectious agents are applied as substitutes for immunity in MM. Immunotherapies including monoclonal antibodies, immune checkpoints inhibitors, affinity- enhanced T cells, chimeric antigen receptor T cells and dendritic cell vaccines are revolutionizing MM treatment. By suppressing the pro-inflammatory milieu and pathogens, prophylactic and therapeutic antibiotics represent anti-tumor and anti-infection properties. It is expected that deeper understanding of infection, immunity and tumor physio-pathologies in MM will accelerate the optimization of combined therapies, thus improving prognosis in MM.

Effects of Epstein-Barr virus infection on the development of multiple myeloma after liver transplantation

Reduced cellular immune function in patients after liver transplantation easily results in many types of viral infections, such as Epstein-Barr virus. Epstein-Barr virus is a Γ-herpesvirus and is related to many malignant diseases, especially epithelial and lymph tumors. The abnormal interaction of cluster of differentiation 40 with cluster of differentiation 40 ligand and expression of cluster of differentiation 40 ligand are considered closely related to the development of myeloma cells. This study explored the influence and mechanism of Epstein-Barr virus infection on the phenotype and biological behavior of myeloma cells after liver transplantation. Flow cytometry was used to detect coexpression of cluster of differentiation 40 and cluster of differentiation 40 ligand in 10 samples of freshly isolated multiple myeloma cells. Cluster of differentiation 40 and cluster of differentiation 40 ligand were coexpressed in sample Nos. 5, 8, 9, and 10, particularly in sample No. 5. Western blot analysis was used to detect the expression of the Epstein-Barr virus antigens latent membrane protein 1 and Epstein-Barr virus nuclear antigen 2 in the multiple myeloma cell line RPMI 8226 infected with Epstein-Barr virus. The antigen expression indicated that Epstein-Barr virus can infect multiple myeloma virus cells in vitro. Reverse transcription-polymerase chain reaction revealed upregulated expression of cluster of differentiation 40 ligand on the infected RPMI 8226 cells, which may be involved in the anti-apoptosis activity of the infected cells. Confocal microscopy showed that pairs of molecules of cluster of differentiation 40, cluster of differentiation 40 ligand, and latent membrane protein 1 were colocalized on the surface of the infected cells. CXC chemokine receptor 4 was upregulated on the RPMI 8226 cells after Epstein-Barr virus infection. The migratory ability of the infected cells improved in the presence of the chemokine stromal cell-derived factor-1α. Anti-apoptosis and migration are known important biological characteristics of malignant cells. Our results indicate the involvement of Epstein-Barr virus in the origin and development of multiple myeloma. The risk of multiple myeloma increases when Epstein-Barr virus infects B cells in the germinal center, which may result in an anti-apoptosis effect of B cells and an improved ability to migrate from the germinal center to peripheral blood.

Vaccination with immature dendritic cells combined with CD40mAb induces protective immunity against B lymphoma in hu-SCID mice

Dendritic cells (DCs) pulsed by tumor antigens have been widely used as tumor vaccines to specifically trigger the cytotoxicity of CD8+ T cells. But the tumor microenviroment with enriched immunosuppressants hampered DC maturation and co-stimulation. CD40/CD40L signaling, one of the most important co-stimulatory molecules is capable of effectively skewing the immune response by promoting DCs maturation and co-stimulation. To establish a novel specific immunotherapeutic approach for the use of DC vaccine in the treatment of B lymphoma, hu-SCID mice bearing B lymphoma were vaccinated by different combination of tumor antigen pulsed DC or imDC vaccines and immune-enhancing agencies such as agonist CD40mAb and T cells. The results of immature DCs combined with agonistic CD40mAb were encouraging with achievement of tumor regression and induction of antigen-specific immune responses. These findings demonstrated the potential utility of imDC-based tumor vaccination combining with agonistic CD40mAb in the treatment of malignant lymphoma.

Preparation and characterization of a novel chimeric antibody against human CD40 with the potential to inhibit Daudi cell proliferation

5C11, a murine monoclonal antibody with a high specificity for human CD40 molecule, is a promising candidate for cancer targeting therapy. We have therefore attempted to construct a humanized antibody of 5C11 to minimize its immunogenicity for potential clinical use. A chimeric version of 5C11 (ch-5C11) was generated by transferring these mouse variable regions onto a human framework. This chimeric antibody retained reactivity to human CD40. In vitro, ch-5C11 could effectively inhibit B lymphoma Daudi cell proliferation, suggesting that it might have the potential to be developed for future clinical use.

Human-like mouse models for testing the efficacy and safety of anti-beta2-microglobulin monoclonal antibodies to treat myeloma

PURPOSE

We showed recently that anti-beta2-microglobulin (beta2M) monoclonal antibodies (mAb) have remarkably strong apoptotic effects on myeloma cells in vitro and in SCID-hu mice. However, whether the mAbs will be therapeutic and safe in the treatment of myeloma patients, in whom every tissue expresses low densities of MHC class I molecules and elevated levels of soluble beta2M are present, remains to be determined.

EXPERIMENTAL DESIGN

In this study, human-like myeloma mouse models (HLA-A2-transgenic NOD/SCID mice) were developed, which express mature and functional human MHC class I (HLA-A2 and human beta2M) on murine organs and present high levels of circulating human beta2M derived from human myeloma cells. Myeloma-bearing mice were treated intraperitoneally with anti-beta2M mAbs, and the distribution and effects of the mAbs on normal organs and established tumors were examined.

RESULTS

Our results show that anti-beta2M mAbs were effective in suppressing myeloma growth in treated mice. The therapeutic efficacy of the mAbs in these mice are comparable with those observed in myeloma-bearing nontransgenic NOD/SCID mice in which no human MHC class I is expressed on murine organs. Furthermore, although the mAbs can be detected on different organs, no tissue damage or cell apoptosis was observed in the mice.

CONCLUSION

Based on the antimyeloma efficacy and low toxicity in the mice, our study suggests that anti-beta2M mAbs may be safe and the tissue-expressing and soluble beta2M may not compromise their therapeutic effects in myeloma patients. This study provides further support for the future application of the mAbs as therapeutic agents for multiple myeloma.

Differential responses of human B-lymphocyte subpopulations to graded levels of CD40-CD154 interaction

Naïve and memory B-lymphocyte populations are activated by CD154 interaction through cell-surface CD40. This interaction plays an important role in the regulation of the humoral immune response, and increasing evidence indicates that fine variation in CD40 binding influences B lymphocytes, macrophages and dendritic cells in murine models. Here we have investigated whether and how variations in the intensity of the CD40-CD154 interaction could contribute to differential regulation of human B-lymphocyte populations. Proliferation and differentiation of B lymphocytes were monitored in response to graded levels of CD40 stimulation in the presence of interleukin (IL)-2, IL-4 and IL-10. Our results show that the level of CD154 binding to CD40 on B lymphocytes can directly influence the evolution of CD19(+) CD27(-) and CD19(+) CD27(+) cell populations. Furthermore, proliferation, global expansion of CD19(+) cells and emergence of CD38(++) CD138(+) cells, as well as immunoglobulin G (IgG) and IgM secretion, were affected by the level of exposure of B lymphocytes to CD154. These results suggest that the CD40-CD154 interaction is more like a rheostat than an on/off switch, and its variation of intensity may play a role in the regulation of B-lymphocyte activation following the primary and/or secondary humoral immune response.