Bispecific antibody targeting both B7-H3 and PD-L1 exhibits superior antitumor activities.

Clinical application of PD-1 and PD-L1 monoclonal antibodies (mAbs) is hindered by their relatively low response rates and the occurrence of drug resistance. Co-expression of B7-H3 with PD-L1 has been found in various solid tumors, and combination therapies that target both PD-1/PD-L1 and B7-H3 pathways may provide  additional therapeutic benefits. Up to today, however, no bispecific antibodies targeting both PD-1 and B7-H3 have reached the clinical development stage. In this study, we generated a stable B7-H3×PD-L1 bispecific antibody (BsAb) in IgG1-VHH format by coupling a humanized IgG1 mAb against PD-L1 with a humanized camelus variable domain of the heavy-chain of heavy-chain antibody (VHH) against human B7-H3. The BsAb exhibited favorable thermostability, efficient T cell activation, IFN-γ production, and antibody-dependent cell-mediated cytotoxicity (ADCC). In a PBMC humanized A375 xenogeneic tumor model, treatment with BsAb (10 mg/kg, i.p., twice a week for 6 weeks) showed enhanced antitumor activities compared to monotherapies and, to some degree, combination therapies. Our results suggest that targeting both PD-1 and B7-H3 with BsAbs increases their specificities to B7-H3 and PD-L1 double-positive tumors and induces a synergetic effect. We conclude that B7-H3×PD-L1 BsAb is favored over mAbs and possibly combination therapies in treating B7-H3 and PD-L1 double-positive tumors.

Li HY ，Chen YL ，Deng XN ，Li HH ，Tan J ，Liu GJ ，Zheng YJ ，Pei M ，Peng KT ，Yue LL ，Chen XJ ，Liu Y ，Zhao YS ，Wang CH ... -  《-》

Blocking PD-1/PD-L1 by an ADCC enhanced anti-B7-H3/PD-1 fusion protein engages immune activation and cytotoxicity.

Antibody therapy based on PD-1/PD-L1 blocking or ADCC effector has produced significant clinical benefit for cancer patients. We generated a novel anti-B7-H3 antibody (07B) and engineered the Fc fragment to enhance ADCC. To improve efficacy and tumor selectivity, we developed anti-B7-H3/PD-1 bispecific fusion proteins that simultaneously engaged tumor associate marker B7-H3 and immune suppressing ligand PD-L1 as well as enhanced ADCC to promote potent and highly selective tumor killing. Fusion proteins were designed by fusing human PD-1 extra domain to 07B in four different formats and showed good binding capacity to both targets. Indeed, the affinity of fusion proteins to B7-H3 is over 10,000 fold higher compared to that of the analogous PD-L1 and the blocking of fusion proteins to PD-L1 was worse but it greatly enhanced when bound to B7-H3, thus achieving directly PD-L1-blockade to B7-H3-expressing tumor cells. Importantly, IL-2 production was enhanced by fusion proteins from staphylococcal enterotoxin B (SEB) stimulated PBMC. Similarly, cytokines induced by fusion proteins was enhanced when co-cultured with stimulated CD8+ T cells and B7-H3/PD-L1 transfected raji cells. Additionally, fusion proteins improved activation to CD16a by Fc modification and delivered selective cytotoxicity to B7-H3 expressing tumor cells. In conclusion, fusion proteins blocked the PD-1/PD-L1 signal pathway and significantly increased potency of ADCC in a B7-H3-directed manner, thereby selectively activating CD8+ T cells and enhancing natural killing towards tumor. This novel fusion protein with its unique targeting preference may be useful to enhance efficacy and safety of immunotherapy for B7-H3-overexpressing malignancies.

Xu Y ，Xiao Y ，Luo C ，Liu Q ，Wei A ，Yang Y ，Zhao L ，Wang Y ... -  《-》

A bispecific antibody targeting HER2 and PD-L1 inhibits tumor growth with superior efficacy.

Activation of the programmed cell death protein 1 and programmed cell death ligand 1 (PD-1/PD-L1) signaling axis plays important roles in intrinsic or acquired resistance to human epidermal growth factor receptor 2 (HER2)-directed therapies in the clinic. Therefore, therapies simultaneously targeting both HER2 and PD-1/PD-L1 signaling pathways are of great significance. Here, aiming to direct the anti-PD-L1 responses toward HER2-expressing tumor cells, we constructed a humanized bispecific IgG1 subclass antibody targeting both HER2 and PD-L1 (HER2/PD-L1; BsAb), which displayed satisfactory purity, thermostability, and serum stability. We found that BsAb showed enhanced antibody-dependent cell-mediated cytotoxicity (ADCC) activity in vitro. In the late phase of peripheral blood mononuclear cell (PBMC)-humanized HER2+ tumor xenograft models, BsAb showed superior therapeutic efficacies as compared with monoclonal antibodies (mAbs) or combination treatment strategies. In cynomolgus monkeys, BsAb showed favorable pharmacokinetics and toxicity profiles when administered at a 10 mg/kg dosage. Thus, HER2/PD-L1 BsAb was demonstrated as a potentially effective option for managing HER2+ and trastuzumab-resistant tumors in the clinic. We propose that the enhanced antitumor activities of BsAb in vivo may be due to direct inhibition of HER2 signaling or activation of T cells.

Chen YL ，Cui Y ，Liu X ，Liu G ，Dong X ，Tang L ，Hung Y ，Wang C ，Feng MQ ... -  《-》

Bispecific Antibody Expressed by an Oncolytic Herpes Simplex Virus Type 2 Can Transform Heterologous T Cells Into Uniform Tumor Killer Cells.

Jin J ，Wang R ，Yang J ，Hu H ，Wang D ，Cai L ，Fang Z ，Dong S ，Hu S ，Wang Y ，Liu B ... -  《-》

Generation and Characterization of a Bispecific Antibody Targeting Both PD-1 and c-MET.

Bispecific antibodies, BsAbs, are molecules with the ability to bind to two different epitopes on the same or different antigens. c-MET, cellular-mesenchymal to epithelial transition factor, is deregulated in many types of human malignancies. Abnormal c-MET activation in cancer correlates with poor prognosis. PD-1, programmed death-1, is an additional inhibitory receptor expressed by T cells. Blocking the interactions between PD-1 and PD-L1 has emerged as a promising immunotherapy for treating cancer. The goal of this study was to identify a novel bispecific antibody targeting both c-MET and PD-1 as an anti-cancer therapeutic candidate. The BsAb was produced using 293E expression system and purified by Protein A affinity chromatography. Then the binding specificity and affinity of the BsAb was examined by FACS and biolayer light interferometry. The ability of the BsAb to inhibit the proliferation of tuman cells was measured using the CellTiter 96 Aqueous One Solution Cell Proliferation Assay kit; the potential signaling pathway involved was identified by Western Blot. Cytokine secreted by PHA-L stimulated PBMC was measured by ELISA. Effects of BsAb on PBMC-mediated lysis of MKN45 cells was measured by LDH cytotoxicity assay. Based on the original sequences of PD-1 and c-MET mAb, a BsAb gene was designed, cloned into pCEP4 vector for expression in 293E cells. The BsAb was obtained after purification of the cell culture supernatant. It can bind to PD-1 and c-MET simultaneously, the calculated affinity was 11.5 nM for PD-1 and 9.09 nM for c-MET. The BsAb enhanced IFN-γ production over control IgG by 2-3 folds. It also inhibit the c-MET pathway activation and the proliferation of tumor cells significantly, comparable to JnJ-38877605. The BsAb showed dose-dependent cytotoxic activity against MKN45 cells. Our results indicated that a novel BsAb recognizing PD-1 and c-MET was successfully generated. It could redirect T cells to kill tumor cells, while retaining its inherent ability to restore T cells and inhibit tumor cells. With this potential, this BsAb could be developed as a therapeutic candidate for the treatment of various solid tumors.

Wu Y ，Yu M ，Sun Z ，Hou W ，Wang Y ，Yuan Q ，Mo W ... -  《-》