Abstract 5877: Disulfiram and its metal complexes reversed hypoxia induced stemness and synergized with first line drugs in primary patient derived pancreatic ductal adenocarcinoma cells
Authors: Small Benjamin J. , Nkeonye Ogechi , Kannappan Vinodh , Kumarasamy Shalini , Butcher Kate , Azar Karim , Rajendran Gowtham , Lakshmanan Yoshitha Lakshmanan , Morris Mark , Heeschen Christopher , Wang Yaohe , Wang Weiguang 
Published: March 2024

Abstract
Pancreatic ductal adenocarcinoma (PDAC) has a dismal 5-year survival rate (12%) and is predicted to become the second leading cause of cancer related deaths by 2030. The main treatment option for advanced PDAC, gemcitabine (GEM) and nab-paclitaxel (PAC) chemotherapy, has limited efficacy due to adverse toxicities and chemoresistance. Extensive desmoplasia in the PDAC microenvironment induces hypoxia that drives epithelial to mesenchymal transition (EMT) and promotes cancer stem cells (CSCs) leading to metastasis and acquired resistance. Drugs that target CSCs and EMT to overcome chemoresistance could improve patient outcome. Disulfiram (DSF), an FDA approved anti alcoholism drug, has excellent anticancer activity on chelation with Cu2+/Zn2+ ions to form the anticancer metabolites, Copper or Zinc Diethyldithiocarbamate (CuDDC or ZnDDC). The anticancer application of the current oral version of DSF is prevented by its short plasma half-life (&lt; 4 minutes) and separate administration of oral Cu/Zn supplement leading to bioavailability issues. A stable, long circulating, injectable formulation of DSF, CuDDC or ZnDDC may overcome these pharmacokinetic issues. In this study albumin was used to develop soluble, stable and homogenous CuDDC and ZnDDC nanoparticles (Alb-CuDDC, Alb-ZnDDC) and their efficacy was compared with free DSF-Cu in a panel of normoxic, hypoxic and spheroid cultures of patient PDAC cells derived from primary, circulating and metastatic sites. Hypoxia and spheroid cultures of PDAC cells were highly resistant to GEM and PAC and had increased expression of CSC markers such as ALDH, CD133, ABCG2 and CA9. Alb-CuDDC and Alb-ZnDDC were cytotoxic to all PDAC cells (IC50s ~300 nM and ~7000 nM, respectively) in normoxia and hypoxia and synergized with GEM and PAC. While DSF-Cu and Alb-CuDDC significantly reduced the expression of CSC markers and inhibited sphere reformation and migration of PDAC cells, Alb-ZnDDC was less effective in inhibiting these features. Therefore, the ability of PDAC cells to acquire resistance to Alb-ZnDDC was investigated. After long term exposure (&gt; 4 months) to increasing doses of each drug (DSF-Cu, Alb-CuDDC and Alb-ZnDDC), PANC1 and BXPC3 PDAC cells acquired resistance only to Alb-ZnDDC. PANC1ZR6 and BXPC3ZR5 resistant cells showed increased expression of CSC markers and significant cross-resistance to PAC and GEM suggesting multidrug resistance. Importantly, no cross-resistance to Alb-CuDDC or DSF-Cu was observed, suggesting alternative mechanisms for Alb-ZnDDC. RNA sequencing is underway to identify potential mechanisms involved. To conclude, albumin formulation improved the solubility and stability of DSF-metal complexes. Alb-CuDDC targets CSCs and overcomes resistance in PDAC, similar to free DSF-Cu. Alb-ZnDDC may have alternative mechanisms which are yet to be elucidated.
Citation Format: Benjamin J. Small, Ogechi Nkeonye, Vinodh Kannappan, Shalini Kumarasamy, Kate Butcher, Karim Azar, Gowtham Rajendran, Yoshitha Lakshmanan Lakshmanan, Mark Morris, Christopher Heeschen, Yaohe Wang, Weiguang Wang. Disulfiram and its metal complexes reversed hypoxia induced stemness and synergized with first line drugs in primary patient derived pancreatic ductal adenocarcinoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5877.