A Novel CD3/BCMA Bispecific T-cell Redirecting Antibody for the Treatment of Multiple Myeloma.

Multiple myeloma (MM) is a B-cell malignancy for which new treatments are urgently needed. Redirecting the activity of T cells by bispecific antibodies against tumor cells is a potent approach. The B-cell maturation antigen (BCMA) is a highly plasma cell-selective protein and therefore is an ideal therapeutic target for T-cell redirecting therapies. The main objective of this work is to target the BCMA by generating BCMA-specific murine monoclonal antibody and construct a cluster of differentiation 3 (CD3)/BCMA-directed tandem diabodies (Tandab). In brief, using standard hybridoma technology, we developed a novel BCMA-specific monoclonal antibody (clone 69G8), that specifically bind with BCMA+ cell lines and MM patient sample; whereas BCMA- cells were not recognized. For T cells by bispecific antibodies application, we constructed a Tandab (CD3/BCMA) simultaneously targeting both CD3 and BCMA and our studies demonstrated that Tandab (CD3/BCMA) was functional with specific binding capability both for CD3+ cells and BCMA+ cells. It induced selective, dose-dependent lysis of BCMA+ cell lines, activation of T cells, release of cytokines and T-cell proliferation; whereas BCMA- cells were not affected. Furthermore, we demonstrated that Tandab activity correlates with BCMA expression, with higher potency observed in highly BCMA expressing tumor cells. In vivo, the purified Tandab (CD3/BCMA) significantly inhibited the tumor growth in a subcutaneous NCI-H929 xenograft model. Taken together, these results show that the Tandab (CD3/BCMA) displays potent and selective anti-MM activities and represents a promising immunotherapeutic for the treatment of MM.

A Novel Blockade CD47 Antibody With Therapeutic Potential for Cancer.

Macrophages as components of the innate immune system play a critical role in antitumor responses. Strategies for targeting CD47 are becoming a hot spot for cancer therapy. The expression of CD47 is exercised by macrophages to make a distinction between "self" or "nonself." Anti-CD47 antibodies block the interaction between macrophage signal regulatory protein-α (SIRPα) and tumor surface CD47. In this study, we report and assess a novel anti-CD47 blocking antibody named 2C8, which exhibits high affinity and tremendous anticancer effects. More concretely, 2C8 significantly induces macrophages, including protumorigenic subtype M2 macrophages killing tumor cells in vitro, and is revealed to be more effective than commercially available anti-CD47 mAb B6H12.2. In vivo, 2C8 controls tumor growth and extends survival of xenograft mice. The antitumor ability of 2C8 might be applicable to many other cancers. The generation of a novel CD47 antibody contributes to consolidating clinical interest in targeting macrophages for the treatment of malignancy and, moreover, as a supplement therapy when patients are resistant or refractory to other checkpoint therapies or relapse after such treatments.

Bispecific CD3-HAC carried by E1A-engineered mesenchymal stromal cells against metastatic breast cancer by blocking PD-L1 and activating T cells.

BACKGROUND: PD-1/PD-L1 blockade can confer durable benefits in the treatment of metastatic cancers, but the response rate remains modest and potential adverse effects occur sometimes. Concentrating immunotherapeutic agents at the site of disease was believed to break local immune tolerance and reduce systemic toxicity. E1A-engineered mesenchymal stromal cell (MSC.E1A) was an attractive transfer system that preferentially homing and treating cancer metastasis, through which the tumor cells were modified by locally replicated adenoviruses to release CD3-HAC, a bifunctional fusion protein that anti-CD3 scfv linked with high-affinity consensus (HAC) PD-1. Subsequently, CD3-HAC, wbich was bound on PD-L1-positive breast cancer cells, recruited T cells to exhibit a potent antitumor immunity incombination with immune checkpoint blockade. METHODS: We constructed the CD3-HAC gene driven by human telomerase reverse transcriptase (hTERT) promoter into an adenoviral vector and the E1A gene into the lentiviral vector. The homing property of MSCs in vivo was analyzed with firefly luciferase-labeled MSCs (MSC.Luc) by bioluminescent imaging (BLI). The cytotoxicity of T cells induced by CD3-HAC towards PD-L1-positive cells was detected in vitro and in vivo in combination with 5-FU. RESULTS: Our data suggest that CD3-HAC could specifically bind to PD-L1-positive tumor cells and induce lymphocyte-mediated lysis effectively both in vitro and in vivo. The intervention with HAC diminished the effects of PD-1/PD-L1 axis on T cells exposed to MDA-MB-231 cells and increased lymphocytes activation. MSCs infected by AdCD3-HAC followed by LentiR.E1A could specially migrate to metastasis of breast cancer and produce adenoviruses in the tumor sites. Furthermore, treatment with MSC.CD3-HAC.E1A in combination with 5-FU significantly inhibited the tumor growth in mice. CONCLUSIONS: This adenovirus-loaded MSC.E1A system provides a promising strategy for the identification and elimination of metastasis with locally released immuno-modulator.

Paeoniflorin inhibits macrophage-mediated lung cancer metastasis.

Alternatively activated macrophages are more frequently involved in tumor growth, angiogenesis, and immunosuppression. A previous study showed that paeoniflorin, the major active constituent of Paeonia lactiflora Pallas, can inhibit tumor growth and lung metastases of Lewis lung tumor-bearing mice. This study tried to investigate whether paeoniflorin inhibited lung cancer metastasis by inhibiting the alternative activation of macrophages (M2 macrophage). Using a viability assay, the cytotoxicity of paeoniflorin on Lewis lung cancer cells and peritoneal macrophages were investigated. In vitro scratch wound and in vivo lung metastasis experiments were used to test the ability to inhibit the migration of paeoniflorin and the function of M2 macrophages. Flow cytometry was performed to test the cell cycle of Lewis lung cancer cells, and to test the M2 macrophages in peritoneal macrophages and subcutaneous transplantable tumor. It was found that paeoniflorin showed no inhibitory effect on the growth of Lewis lung cancer cells and peritoneal macrophages of mouse in vitro. Paeoniflorin could attenuate the migration of LLC stimulated by alternatively activated macrophages (stimulated for 24 h and 48 h, paeoniflorin 1, 3, 10, 30, 100 µmol·L(-1), P < 0.01 or P < 0.05 vs control group). Paeoniflorin could decrease the cell populations at S phases (paeoniflorin 10, 30, 100 µmol·L(-1), P < 0.05 vs control group) and increase the cell populations at G0-G1 phases of Lewis lung cancer cells (paeoniflorin 100 µmol·L(-1), P < 0.05 vs control group) and reduce the numbers of M2 macrophages in peritoneal macrophages induced by IL-4 (paeoniflorin 1, 3, 10, 30, 100 µmol·L(-1), P < 0.01 vs Control group). Paeoniflorin could reduce lung metastasis of Lewis lung cancer cells xenograft and decrease the numbers of M2 macrophages in subcutaneous xenograft tumour in vivo (paeoniflorin 20, 40 mg·kg(-1), P < 0.01 vs control group). These results suggest that paeoniflorin could reduce lung metastasis of Lewis lung cancer cells xenograft partly through inhibiting the alternative activation of macrophages.