Abstract PO045: Inhibition of GAS6/AXL improves efficacy of HER2 inhibitor trastuzumab in uterine serous cancer

Objectives: To determine whether inhibition of GAS6/AXL can improve efficacy to the humanized anti-HER2 monoclonal antibody trastuzumab by decreasing uterine serous cancer cell invasion and cell survival in vitro and tumor burden in vivo. Methods: We treated AXL-expressing and HER2-expressing uterine serous cancer cell lines (ARK1, ARK2) with trastuzumab, AVB-500, or trastuzumab plus AVB-500. Clonogenic cell survival assays were performed. Matrigel invasion assays were used to assess the invasive capacity of ARK2 cells after 24 hours of treatment with vehicle, AVB-500, trastuzumab, or trastuzumab plus AVB-500. A proximity ligation assay was used to examine colocalization of HER2/neu and AXL. Western blots were performed to assess the effects of the individual drugs and combination on phosphorylation of HER2/neu and AXL. An intraperitoneal tumor model with 10 million ARK1 cells was treated with vehicle, AVB-500, trastuzumab, or trastuzumab plus AVB-500 for 35 days. The number, size, and volume of tumor nodules were measured. GraphPad Prism was used for statistical analysis. Results: We found decreased cell survival by clonogenic assays in ARK1 and ARK2 cells treated with trastuzumab plus AVB-500 compared to trastuzumab alone (relative absorbance 0.155 nm vs 0.202 nm, P=0.015). There was significantly less invasion from treatment with trastuzumab plus AVB-500 than with trastuzumab alone (3.2 vs 17.8 invading tumor cells/hpf, P=0.0004). Western blot showed that cells treated with trastuzumab plus AVB-500 had reduced phospho-AXL compared to cells treated with AVB-500 or trastuzumab alone. Furthermore, the proximity ligation assay demonstrated co-localization of the AXL and HER2 receptors in both ARK1 and ARK2 cells indicating a physical closeness that could account for this co-regulation. We found that mice treated with trastuzumab plus AVB-500 developed significantly less tumor burden than mice treated with trastuzumab alone (0.03205 g vs 0.08316 g, P= 0.024), AVB-500 alone (0.0320 g vs 0.1638 g, P<0.0001), and vehicle alone (0.03205 g vs 0.1154 g, P= 0.0395). Conclusions: The GAS6/AXL inhibitor AVB-500 potentiated the effect of trastuzumab to decrease uterine serous cancer cell proliferation and invasion in vitro and tumor burden in vivo likely through AXL and HER2 complexes.

Citation Format: Joan Tankou, Michael Toboni, Hollie Noia, Alyssa Oplt, Daniel Wilke, Dineo Khabele, Lindsay Kuroki, Andrea Hagemann, Carolyn McCourt, Premal Thaker, David Mutch, Matthew Powell, Katherine Fuh. Inhibition of GAS6/AXL improves efficacy of HER2 inhibitor trastuzumab in uterine serous cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference: Endometrial Cancer: New Biology Driving Research and Treatment; 2020 Nov 9-10. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(3_Suppl):Abstract nr PO045.

The influence of health knowledge in shaping political priorities: examining HIV/AIDS knowledge and public opinion about global health and domestic policies

Public opinion polls have historically indicated that the US public favours domestic over global priorities. It is not known what influence health knowledge has in shaping public opinion about domestic and global health policy. This study examines how knowledge of HIV/AIDS is related to the rated importance of domestic and global health issues. Participants were recruited to participate in an electronic survey (N = 995) and were predominantly White (86.3%), married (61.9%) and female (71.8%). HIV/AIDS knowledge was significantly associated with both domestic (β = 0.12, p < 0.05) and global health (β = 0.14, p < 0.01) priorities after controlling for sociodemographic variables. In addition, global health was found to act as a mediator between HIV/AIDS knowledge and perceived importance of domestic issues. Study findings suggest that those with greater HIV/AIDS knowledge rate global health issues higher, which in turn affects ratings of more domestic issues. This research has implications for ways to gain support for implementation of public health policy through increasing health knowledge.