Preclinical Synergistic Combination Therapy of Lurbinectedin with Irinotecan and 5-Fluorouracil in Pancreatic Cancer.

Pancreatic cancer is a devastating disease with a poor prognosis. Novel chemotherapeutics in pancreatic cancer have shown limited success, illustrating the urgent need for new treatments. Lurbinectedin (PM01183; LY-01017) received 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 stalls and degrades RNA Polymerase II and introduces breaks in DNA, causing subsequent apoptosis. We now demonstrate lurbinectedin's highly efficient killing of human-derived pancreatic tumor cell lines PANC-1, BxPC-3, and HPAF-II as a single agent. We further demonstrate that a combination of lurbinectedin and irinotecan, a topoisomerase I inhibitor with FDA approval for advanced pancreatic cancer, results in the synergistic killing of pancreatic tumor cells. Western blot analysis of combination therapy indicates an upregulation of γH2AX, a DNA damage marker, and the Chk1/ATR pathway, which is involved in replicative stress and DNA damage response. We further demonstrate that the triple combination between lurbinectedin, irinotecan, and 5-fluorouracil (5-FU) results in a highly efficient killing of tumor cells. Our results are developing insights regarding molecular mechanisms underlying the therapeutic efficacy of a novel combination drug treatment for pancreatic cancer.

Preclinical studies with ONC201/TIC10 and lurbinectedin as a novel combination therapy in small cell lung cancer (SCLC).

The American Cancer Society estimates that ~15% of all lung cancers are categorized as small cell lung cancer (SCLC) with an overall five-year survival rate of less than 7%. Due to disease aggressiveness, more other malignancies, the standard of care is based on clinical efficacy rather than helpful biomarkers. Lurbinectedin is a small molecule RNA polymerase II inhibitor that binds the minor groove of DNA to induce double-strand breaks. Lurbinectedin has efficacy towards SCLC cells at sub-nM concentration and received accelerated FDA approval in 2020 for metastatic SCLC that progressed on platinum-based therapy. ONC201/TIC10 is a TRAIL pathway-inducing compound that with demonstrated clinical efficacy in H3K27M-mutated diffuse midline glioma and neuroendocrine tumors, in early phase clinical trials. We hypothesized that combining ONC201 and lurbinectedin may yield synergistic and targeted killing of SCLC cells. SCLC cell lines H1048, H1105, H1882, and H1417 were treated with ONC201 and lurbinectedin and cell viability was determined using a CellTiter-Glo assay using varying drug concentrations. Synergistic growth inhibition of SCLC cells was noted with combination of ONC201 and lurbinectedin. Induction of the integrated stress response mediator ATF4 and CHOP was observed with ONC201 and lurbinectedin along with induction of PARP cleavage indicative of apoptosis in response to cellular stress. Additionally, SCLC lines treated with the combination therapy displayed increased DNA breakage-related proteins such as phosphorylated Chk-1, Wee1 and γ-H2AX. Combination index revealed the most potent synergy occurred at the concentrations of 0.16 µM ONC201 and 0.05 nM lurbinectedin in the H1048 cell line, demonstrating highly efficient and selective killing of these tumor cells in vitro. While these therapies showed potency against the cell lines derived from SCLC patients, it is noteworthy that the combination showed significantly less toxicity to healthy human lung epithelial cells. Future studies could explore the combination of ONC201 and lurbinectedin in SCLC cell lines, SCLC patient-derived organoids, other tumor types, including in vivo studies and clinical translation.

Absence of Biomarker-Driven Treatment Options in Small Cell Lung Cancer, and Selected Preclinical Candidates for Next Generation Combination Therapies.

Lung cancer is the second most common cancer in the United States, and small cell lung cancer (SCLC) accounts for about 15% of all lung cancers. In SCLC, more than other malignancies, the standard of care is based on clinical demonstration of efficacy, and less on a mechanistic understanding of why certain treatments work better than others. This is in large part due to the virulence of the disease, and lack of clinically or biologically relevant biomarkers beyond routine histopathology. While first line therapies work in the majority of patients with extensive stage disease, development of resistance is nearly universal. Although neuroendocrine features, Rb and p53 mutations are common, the current lack of actionable biomarkers has made it difficult to develop more effective treatments. Some progress has been made with the application of immune checkpoint inhibitors. There are new agents, such as lurbinectedin, that have completed late-phase clinical testing while other agents are still in the pre-clinical phase. ONC201/TIC10 is an imipridone with strong in vivo and in vitro antitumor properties and activity against neuroendocrine tumors in phase 1 clinical testing. ONC201 activates the cellular integrated stress response and induces the TRAIL pro-apoptotic pathway. Combination treatment of lurbinectedin with ONC201 are currently being investigated in preclinical studies that may facilitate translation into clinical trials for SCLC patients.

Therapeutic Targeting of Autophagy in Pancreatic Ductal Adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease characterized by early metastasis, late detection, and poor prognosis. Progress towards effective therapy has been slow despite significant efforts. Novel treatment approaches are desperately needed and autophagy, an evolutionary conserved process through which proteins and organelles are recycled for use as alternative energy sources, may represent one such target. Although incompletely understood, there is growing evidence suggesting that autophagy may play a role in PDAC carcinogenesis, metastasis, and survival. Early clinical trials involving autophagy inhibiting agents, either alone or in combination with chemotherapy, have been disappointing. Recently, evidence has demonstrated synergy between the MAPK pathway and autophagy inhibitors in PDAC, suggesting a promising therapeutic intervention. In addition, novel agents, such as ONC212, have preclinical activity in pancreatic cancer, in part through autophagy inhibition. We discuss autophagy in PDAC tumorigenesis, metabolism, modulation of the immune response, and preclinical and clinical data with selected autophagy modulators as therapeutics.