Abstract B026: Preclinical synergistic combination therapy of lurbinectedin with irinotecan and 5-fluorouracil in pancreatic cancer
Authors: Tummala Tej , Cruz Arielle De La , Uruchurtu Ash , Liguori Nicholas R , Abbas Abbas E , Zhang Leiqing , Azzoli Christopher , Zhou Lanlan , El-Deiry Wafik S 
Published: December 2023

Abstract
Pancreatic cancer is a devastating disease with an overall five-year survival rate of ~12% according to the American Cancer Society. Novel chemotherapeutics and targeted therapies in pancreatic cancer have shown limited success, illustrating the urgent need for new treatments. Lurbinectedin (PM01183; LY-01017) received accelerated FDA approval in 2020 for metastatic small cell lung cancer on or after platinum-based chemotherapy and is currently undergoing clinical trials in a variety of tumor types. Lurbinectedin is a chemotherapeutic synthetic tetrahydroisoquinoline alkaloid that inhibits active transcription by binding to guanine rich sequences in the minor groove of DNA. Lurbinectedin has been shown to reduce oncogenic transcription by stalling and degrading RNA Polymerase II and inducing breaks in DNA, causing subsequent apoptosis. We now demonstrate lurbinectedin’s highly efficient killing of pancreatic tumor cells as a single agent in PANC-1, BxPC-3, and HPAF-II cell lines, with 72-hour IC-50s ranging from 0.266 – 0.964 nM. We further demonstrate that a combination of lurbinectedin and irinotecan, a topoisomerase I inhibitor with FDA approval for advanced pancreatic cancer, results in synergistic killing of pancreatic tumor cells in vitro. Synergism was calculated using SynergyFinder, with HSA scores exceeding 15 in every cell line (synergy scores greater than 10 are considered synergistic according to the website manufacturer). Western Blot analysis of combination therapy indicates an upregulation of γH2AX and ATR, indicating DNA damage likely plays a role in the synergistic effects of the drugs. Bcl-2 downregulation in combination therapy indicates that the Bcl-2 family proteins likely play a role in the apoptosis of the cancer cells. Cytokine profiling analysis indicates an upregulation of the Fas apoptosis-inducing ligand under lurbinectedin and irinotecan monotherapy and combination therapy. VEGF and prolactin were downregulated in combination therapy. We further demonstrate that the triple combination between lurbinectedin, irinotecan, and 5-Fluorouracil (5-FU) enhances % inhibition as each drug concentration increases, and the presence of lurbinectedin enhances the synergism between irinotecan and 5-FU. Our results are developing insights regarding molecular mechanisms underlying therapeutic efficacy of a novel combination drug treatment for pancreatic cancer.
Citation Format: Tej Tummala, Arielle De La Cruz, Ash Uruchurtu, Nicholas R Liguori, Abbas E Abbas, Leiqing Zhang, Christopher Azzoli, Lanlan Zhou, Wafik S El-Deiry. Preclinical synergistic combination therapy of lurbinectedin with irinotecan and 5-fluorouracil in pancreatic cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr B026.