Abstract P001: The anti-angiogenic antibody BD0801 demonstrates better anti-tumor activity than bevacizumab and synergize with chemotherapies in multiple tumor models

BackgroundRegulatory T cell (Tregs) inhibit activity of anti-tumor T cells, and have been shown to limit checkpoint inhibitor effectiveness. Depletion of Tregs seems desirable during immunotherapy, but chronic Treg depletion with antibody therapies can lead to serious autoimmune adverse events. Compared to antibodies, the fusion protein E7777 (IL-2/diphtheria toxin) has a relatively short half-life in circulation, which allows for transient and selective Treg depletion. The potential therapeutic benefit of combining E7777 with anti-PD-1 was tested in syngeneic solid tumor models.MethodsCT26 colon and H22 liver cancer tumors were implanted subcutaneously in immunocompetent BALB/c mice. E7777 (2.5 mcg/mouse, i.v.) was given on a Q7Dx3 schedule. Anti-murine PD-1 was given (100 mcg/mouse, i.v.) Q4Dx5. Groups of 16 mice received each agent as monotherapy or in combinations. Sequencing of combination administration was also varied: Group 4 started treatment on the same day; Group 5 received E7777 2 days prior to start of anti-PD-1; Group 6 received anti-PD-1 first. Tumor growth was compared across all groups. In survival studies, mice were treated for 3 weeks and observed with twice weekly tumor measurements. In other experiments, tumors, tumor-draining lymph nodes, and spleens were examined by IHC and by flow cytometry of immune cells from dissociated tissues at defined points, for immune biomarkers.ResultsFigure 1 shows additive benefit from the E7777 + anti-PD-1 combinations over either monotherapy. Most importantly, figure 2 and table 1 show significantly enhanced overall survival from a 3 week course of combinations compared to either agent alone (p<0.005) or to vehicle controls (p<0.000001). There was no clear distinction among different sequencing regimens. Benefit correlated with enhanced CD8:Treg ratios in tumors.Abstract 208 Figure 1Tumor growth in s.c. syngeneic solid tumors. N=16/groupAbstract 208 Figure 2Overall survival in s.c. syngeneic models. N=16/groupAbstract 208 Table 1Calculated median survivalConclusionsDepletion of Tregs by E7777 significantly increased anti-tumor activity and durably extended overall survival compared to treatment with anti-PD-1 alone in syngeneic solid tumor models. Clinical studies of a combination of the two agents are planned.Ethics ApprovalAll studies were conducted at Crown Bio, and were approved by the Crown Bio IACUC.

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Therapeutic Application of Brain-Specific Angiogenesis Inhibitor 1 for Cancer Therapy

Cancers ◽

10.3390/cancers13143562 ◽

2021 ◽

Vol 13 (14) ◽

pp. 3562

Author(s):

Mitra Nair ◽

Chelsea Bolyard ◽

Tae Jin Lee ◽

Balveen Kaur ◽

Ji Young Yoo

Keyword(s):

Angiogenesis Inhibitor ◽

Suppressor Gene ◽

Chemotherapeutic Agents ◽

Tumor Models ◽

In Vivo Models ◽

Herpes Simplex Viruses ◽

Multiple Tumor ◽

And Function

Brain-specific angiogenesis inhibitor 1 (BAI1/ADGRB1) is an adhesion G protein-coupled receptor that has been found to play key roles in phagocytosis, inflammation, synaptogenesis, the inhibition of angiogenesis, and myoblast fusion. As the name suggests, it is primarily expressed in the brain, with a high expression in the normal adult and developing brain. Additionally, its expression is reduced in brain cancers, such as glioblastoma (GBM) and peripheral cancers, suggesting that BAI1 is a tumor suppressor gene. Several investigators have demonstrated that the restoration of BAI1 expression in cancer cells results in reduced tumor growth and angiogenesis. Its expression has also been shown to be inversely correlated with tumor progression, neovascularization, and peri-tumoral brain edema. One method of restoring BAI1 expression is by using oncolytic virus (OV) therapy, a strategy which has been tested in various tumor models. Oncolytic herpes simplex viruses engineered to express the secreted fragment of BAI1, called Vasculostatin (Vstat120), have shown potent anti-tumor and anti-angiogenic effects in multiple tumor models. Combining Vstat120-expressing oHSVs with other chemotherapeutic agents has also shown to increase the overall anti-tumor efficacy in both in vitro and in vivo models. In the current review, we describe the structure and function of BAI1 and summarize its application in the context of cancer treatment.

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