Therapeutic antibodies are effective for tumor immunotherapy and exhibit prominent clinical effects. All approved antibody therapeutics utilize IgG as the molecular format. Antibody-dependent cell-mediated cytotoxicity (ADCC) is a key mechanism for tumor cell killing by antibodies. For IgG antibodies, ADCC depends on FcγR-expressing cells, such as natural killer (NK) cells. However, in patients with a high tumor burden, antibody therapeutics may lose efficacy owing to exhaustion of FcγR-expressing effector cells as well as the inhibitory effects of certain FcγRs on effector cells. To achieve more potent effector functions, we engineered an anti-CD20 antibody to contain both IgG Fc and IgA Fc domains. These engineered antibodies interacted with both IgG and IgA Fc receptors (FcγR and FcαR) and recruited a broader range of effector cells, including monocytes, macrophages, neutrophils, and NK cells, thereby enhancing antibody-dependent cellular phagocytosis. Using transgenic mice expressing the FcαRI (CD89) in macrophages, we demonstrated that recombinant antibodies bearing the chimeric IgG and IgA Fc exhibited potent in vivo antitumor activity. Additionally, in a short-term peritoneal model using CD20-transfected LLC target cells, the in vivo cytotoxic activity of hybrid recombinant antibodies was mediated by macrophages with significant reduction in the absence of FcαRI. Our findings supported targeting of FcαRI on monocytes and macrophages for improved tumor immunotherapy.

NF-κB interacting lncRNA (NKILA) has been found to function as a tumor-suppressive role in various human cancers. However, the role of NKILA in rectal cancer is still unknown. The objective of this study is to investigate the clinical value and biological function of NKILA in rectal cancer. The association between NKILA expression and clinical variables including prognosis was estimated in rectal cancer patients. The gain-of-function study of NKILA in rectal cancer cell was conducted to evaluate the effect of NKILA on cell proliferation, migration, invasion, and NF-κB signaling pathway. The results suggested NKILA expression was decreased in rectal cancer tissues and cells, and correlated with clinical stage, T classification, N classification and M classification. NKILA low-expression was an independent poor prognostic factor in rectal cancer patients. NKILA-inhibited rectal cancer cell proliferation, migration, and invasion via suppressing NF-κB signaling. In conclusion, NKILA serves as an antioncogenic lncRNA in rectal cancer.

Since tumors are often infiltrated by macrophages, it would be advantageous to turn these types of cells into cytotoxic effector cells. Here, we have designed a novel bispecific antibody (BsAb) that targets both tumor antigen (CD20) and the FcαRI receptor (CD89). This antibody could be used to lyse tumors by connecting tumor cells to CD89-expressing immune effector cells such as macrophages and neutrophils. Previously there were very limited attempts to exploit FcαRI-expressing cells as effector cells for tumor cell-killing, largely due to the lack of an appropriate model, since mice do not express a human CD89 homolog. In this study, we used a transgenic mouse strain with specific expression of CD89 on macrophages and monocytes. In this transgenic mouse model, the CD89 bispecific antibody showed significant anti-tumor activities, demonstrating that bispecific antibodies can redirect macrophages, including M2 macrophages, to mediate additional effector function in the tumor microenvironment. This approach realized the full potential of the innate immune system and could be applied to other tumor-associated antigens especially the solid tumors, thus has potential to translate into clinical benefits in human cancers.

Disitamab vedotin (RC48) is an HER2-directed antibody-drug conjugate, emerging as an effective strategy for cancer therapy, not only enhance antitumor immunity in previous animal models but also improve clinical outcomes for patients such as with gastric cancer, urothelium carcinoma and HER2 low-expressing breast cancer. Here, we explore the combination therapeutic efficacy of this novel HER2-targeting ADC with immune checkpoint inhibitors in a human HER2-expressing syngeneic breast cancer model. Methods: The human HER2+ cancer cell line is constructed by stably transfection and individual clones were isolated by single-cell sorting. Flow cytometry was performed to determine its binding activity. Cytotoxic effect was determined using an MTT assay with the supplement of RC48. Human PD-1 transgenic mice were used to analyze the in vivo anti-tumor effects of the ADC and its combination therapy with PD-1/PD-L1 antibody. Results:The combination of RC48 and PD-1/PD-L1 immune checkpoint inhibition significantly enhanced tumor suppression and antitumor immunity. Tumor rejection in the synergistic groups was accompanied by massive T-cell infiltration and immune marker activation. Furthermore, the combination therapy promoted immunological memory formation in the tumor-eradication animals, protecting them from tumor rechallenge. Conclusion:A novel HER2-targeting ADC combined with immune checkpoint inhibitors can achieve remarkable effects in mice and elicit long-lasting immune protection in a hHER2+ murine breast cancer model. This study provides insights into the efficacy of RC48 therapeutic activity and a rationale for potential therapeutic combination strategies with immunotherapy.

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Tumor cells become resistant after long-term use of anti-VEGF (vascular endothelial growth factor) agents. Our previous study shows that treatment with a VEGF inhibitor (VEGF-Trap) facilitates to develop tumor resistance through regulating angiogenesis-related genes. However, the underlying molecular mechanisms remain elusive. Histone modifications as a key epigenetic factor play a critical role in regulation of gene expression. Here, we explore the potential epigenetic gene regulatory functions of key histone modifications during tumor resistance in a mouse Lewis lung carcinoma (LLC) cell line. We generated high resolution genome-wide maps of key histone modifications in sensitive tumor sample (LLC-NR) and resistant tumor sample (LLC-R) after VEGF-Trap treatment. Profiling analysis of histone modifications shows that histone modification levels are effectively predictive for gene expression. Composition of promoters classified by histone modification state is different between LLC-NR and LLC-R cell lines regardless of CpG content. Histone modification state change between LLC-NR and LLC-R cell lines shows different patterns in CpG-rich and CpG-poor promoters. As a consequence, genes with different level of CpG content whose gene expression level are altered are enriched in distinct functions. Notably, histone modification state change in promoters of angiogenesis-related genes consists with their expression alteration. Taken together, our findings suggest that treatment with anti-VEGF therapy results in extensive histone modification state change in promoters with multiple functions, particularly, biological processes related to angiogenesis, likely contributing to tumor resistance development.

Regeneration is a unique defense mechanism of liver tissue in response to functional cell loss induced by toxic chemicals or surgical resection. In this study, we found that Islet‐cell autoantigen 69 (Ica69) accelerates liver regeneration in mice. Following 70% partial hepatectomy, both Ica69 mRNA and protein are significantly upregulated in mouse hepatocytes at the early stage of liver regeneration. Compared with the wild‐type mice, Ica69‐deficient mice have more severe liver injury, delayed liver regeneration, and high surgical accidental mortality following hepatectomy. Mechanistically, Ica69 interacts with Pick1 protein to regulate Tgfbr1 protein expression and Tgfβ‐induced Smad2 phosphorylation. Our findings suggest that Ica69 in liver tissue is a new potential target for promoting liver regeneration.

Antibody-dependent cell-mediated cytotoxicity (ADCC) is one of key mechanisms through which antibody therapeutics can lyse tumor target cells. ADCC is usually mediated by IgG through recruiting effector cells, mostly NK cells, via IgG Fc receptor. In order to enhance specific tumor lysis by ADCC, a common strategy is to design a bispecific antibody that binds a tumor cell surface antigen and T cell marker CD3, thus to recruit T cells as effector cells. An example of this type of design is the FDA-approved bispecific antibody blinatumomab. We are interested in designing novel bispecific strategies to achieve improved ADCC effect. Since tumors are often infiltrated by macrophages and neutrophils, it would be advantageous to turn these types of cells into effector cells for ADCC. We have designed several bispecific strategies that can target a tumor associated antigen (TAA) and CD89 (FcαRI). The aim is to lyse tumors through connecting tumor cells to CD89-expressing immune effector cells, such as macrophages and neutrophils. The CD89 bispecific antibodies were produced by HEK293 cells and showed binding activities to both CD89 and TAA. The CD89 bispecific antibodies can recruit CD89-expressing immune cells and induced enhanced tumor cells-killing in human whole blood ADCC assays. Since mouse does not express human CD89 homologue, we generated a transgenic mouse strain with specific expression of CD89 on macrophages and monocytes. In this transgenic mouse model, the CD89 bispecific antibodies showed significant anti-tumor activities, demonstrating that the bispecific antibodies can redirect macrophages, including M2 macrophages, to mediate additional effector function in tumor microenvironment. Citation Format: Bingyu Li, Lijun Xu, Kun Xie, Fei Tao, Renhao Li, Hua Gu, Jianmin Fang. Enhanced antitumor efficacy by recruiting macrophages as effector cells via bispecific antibodies mediated by CD89 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 164. doi:10.1158/1538-7445.AM2017-164