Abstract 367: The heparan sulfate mimetic PG545 inhibits tumor growth in both male and female mouse model of pancreatic ductal adenocarcinoma (PDAC) with sex difference in the effect on cachexia
Authors: Zhong Xiaoling , Dredge Keith , Chirgwin John M. , House Michael G. , Nakshatri Harikrishna , Zimmers Teresa A. 
Published: April 2023

BACKGROUND: Cachexia occurs in up to 80% of PDAC patients and is characterized by weight loss mainly due to muscle and fat wasting. Cachexia leads to functional impairment, reduced anticancer therapy tolerance and increased mortality. PG545, a heparan sulfate (HS) mimetic, shows anticancer activity; however, it is unknown whether sex affects the anticancer activity and what effect PG545 has on cancer associated muscle and fat wasting. Given that many cytokines induced in patients with cancer cachexia can bind HS, the aim of this study was to assess PG545 effects on PDAC cachexia with emphasis on sex difference.

METHODS: PDAC cells were injected into the pancreas of 10-week C57BL/6 male and female mice. The orthotopic tumor-bearing mice were treated with PG545 (10 mg/kg; i.p.). Body weight and body composition were monitored, and tumor and organs were collected. Skeletal muscles were cryosectioned for evaluation of cross-sectional area (CSA). C2C12 myotubes, the in vitro model of muscle wasting, were treated with PDAC cell-derived conditioned medium (CM) without or with PG545 and analyzed for the changes in size. PDAC cell proliferation was assessed by MTT assay.

RESULTS: PG545 treatment markedly reduced tumor mass in both males and females compared to the vehicle controls. PG545 also reduced body weight but the difference gradually dissipated over time despite repeated dosing. However, male mice recovered from the negative effects more slowly than female mice. Similar sex difference was observed in the changes in the PG545-induced lean and fat mass loss. Of note, fat mass in PG545-treated females at the end of experiment was higher than in the vehicle controls. Furthermore, males had more reductions in muscle and fat weights than females in response to PG545. Grip strength in males was weakened by PG545 but returned to the level like that in the vehicle controls at the end, while PG545 did not weaken grip strength in females at the same time points. In addition, males, but not females, had smaller muscle fiber CSA after PG545 treatment versus their vehicle controls. In in vitro assay, PG545 inhibited PDAC cell proliferation, indicating a direct effect on cancer cells. Lastly, opposed to the in vivo effect, PG545 partly prevented myotube wasting induced by PDAC CM.

CONCLUSION: PG545 has strong anti-PDAC activity in both male and female mice, at least partly through inhibition of cancer cell proliferation. Its initial negative effects on cachexia are gradually reversed with male tumor-bearing mice reversing more slowly than females. Because of the protective effect on C2C12 myotubes treated with PDAC CM, PG545 might induce some counteracting factors in vivo in the initial treatment and identification of these factors may offer molecular targets for combination therapy to counteract the negative effects while take advantage of the strong anti-cancer potential.

Citation Format: Xiaoling Zhong, Keith Dredge, John M. Chirgwin, Michael G. House, Harikrishna Nakshatri, Teresa A. Zimmers. The heparan sulfate mimetic PG545 inhibits tumor growth in both male and female mouse model of pancreatic ductal adenocarcinoma (PDAC) with sex difference in the effect on cachexia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 367.