Concurrent Inhibition of the RAS-MAPK Pathway and PIKfyve Is a Therapeutic Strategy for Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC) is characterized by KRAS- and autophagy-dependent growth. Inhibition of the KRAS-RAF-MEK-ERK pathway enhances autophagic flux and dependency, and concurrent treatment with the nonspecific autophagy inhibitor chloroquine (CQ) and ERK-MAPK pathway inhibitors can synergistically block PDAC growth. However, CQ is limited in terms of specificity and potency. To find alternative anti-autophagy strategies, in this study, we performed a CRISPR-Cas9 loss-of-function screen in PDAC cell lines that identified the lipid kinase phosphatidylinositol-3-phosphate 5-kinase (PIKfyve) as a growth-promoting gene. PIKfyve inhibition by the small molecule apilimod resulted in durable growth suppression, with much greater potency than CQ treatment. PIKfyve inhibition caused lysosomal dysfunction, reduced autophagic flux, and led to the accumulation of autophagy-related proteins. Furthermore, PIKfyve inhibition blocked the compensatory increases in autophagic flux associated both with MEK inhibition and with direct RAS inhibition. Accordingly, combined inhibition of PIKfyve and the RAS-MAPK pathway showed robust growth suppression across a panel of KRAS-mutant PDAC models. Growth suppression was due, in part, to potentiated cell-cycle arrest and induction of apoptosis following loss of inhibitor of apoptosis proteins. These findings indicate that concurrent inhibition of RAS and PIKfyve is a synergistic, cytotoxic combination that may represent a therapeutic strategy for PDAC. Significance: PIKfyve inhibition effectively blocks autophagy in multiple models of KRAS-mutant pancreatic cancer and can synergize with inhibitors of members of the RAS-MAPK pathway, providing an effective combination strategy for pancreatic cancer.

DeLiberty JM ，Roach MK ，Stalnecker CA ，Robb R ，Schechter EG ，Pieper NL ，Taylor KE ，Pita LM ，Yang R ，Bang S ，Drizyte-Miller K ，Ackermann SE ，Nicewarner Peña SR ，Baldelli E ，Min SM ，Drewry DH ，Petricoin EF 3rd ，Morris JP 4th ，Der CJ ，Cox AD ，Bryant KL ... -  《-》

Concurrent inhibition of pBADS99 synergistically improves MEK inhibitor efficacy in KRAS(G12D)-mutant pancreatic ductal adenocarcinoma.

Therapeutic targeting of KRAS-mutant pancreatic ductal adenocarcinoma (PDAC) has remained a significant challenge in clinical oncology. Direct targeting of KRAS has proven difficult, and inhibition of the KRAS effectors have shown limited success due to compensatory activation of survival pathways. Being a core downstream effector of the KRAS-driven p44/42 MAPK and PI3K/AKT pathways governing intrinsic apoptosis, BAD phosphorylation emerges as a promising therapeutic target. Herein, a positive association of the pBADS99/BAD ratio with higher disease stage and worse overall survival of PDAC was observed. Homology-directed repair of BAD to BADS99A or small molecule inhibition of BADS99 phosphorylation by NCK significantly reduced PDAC cell viability by promoting cell cycle arrest and apoptosis. NCK also abrogated the growth of preformed colonies of PDAC cells in 3D culture. Furthermore, high-throughput screening with an oncology drug library to identify potential combinations revealed a strong synergistic effect between NCK and MEK inhibitors in PDAC cells harboring either wild-type or mutant-KRAS. Mechanistically, both mutant-KRAS and MEK inhibition increased the phosphorylation of BADS99 in PDAC cells, an effect abrogated by NCK. Combined pBADS99-MEK inhibition demonstrated strong synergy in reducing cell viability, enhancing apoptosis, and achieving xenograft stasis in KRAS-mutant PDAC. In conclusion, the inhibition of BADS99 phosphorylation enhances the efficacy of MEK inhibition, and their combined inhibition represents a mechanistically based and potentially effective therapeutic strategy for the treatment of KRAS-mutant PDAC.

Tan YQ ，Sun B ，Zhang X ，Zhang S ，Guo H ，Basappa B ，Zhu T ，Sethi G ，Lobie PE ，Pandey V ... -  《Cell Death & Disease》

A novel regimen for pancreatic ductal adenocarcinoma targeting MEK, BCL-xL, and EGFR.

Oncogenic KRAS signaling plays a critical role in pancreatic ductal adenocarcinoma (PDAC) biology. Recent studies indicate that the combination of MEK and BCL-xL inhibition is synthetically lethal and holds promise for some types of solid cancers, however, patient response was poorly observed in PDAC predominantly due to amplified EGFR signaling. Here, we leverage the advantage of the combinational treatment strategy and designed a triplet regimen targeting the comprehensive RAS activation networks through simultaneously blocking MEK/BCL-xL/EGFR. The cytotoxicity of trametinib (MEK inhibitor), DT2216 (BCL-xL degrader) and afatinib (pan-EGFR inhibitor) and their combination was tested in patient-derived, primary PDAC cells using a live cell imaging system. Patient-derived xenograft (PDX) model was employed for the evaluation of the therapeutic efficacy and safety of the combinational regimen. Targeted pathway cascades activities were analyzed using multiplex phosphor-immune assays. In vitro comparisons showed the addition of afatinib as a third agent was statistically superior compared to a doublet of trametinib+DT2216 in suppressing cell growth and inducing cell death in all cell lines tested. This triplet similarly demonstrated significant superiority over the doublet of MEK/BCL-xL inhibition in the in vivo murine model. The triplet regimen was well tolerated in vivo. Overall tumor growth rates were significantly reduced in doublet treatment compared to controls, and further reduced in the triplet treatment group. Pathway analysis revealed the addition of afatinib in triplet regimen further inhibited PI3K/AKT effectors of p90RSK, p70S6K, and GSK3α/β along with a secondary pathway of P38 MAPK. Our study identifies an important contribution of EGFR inhibition to elevate the response of PDAC, supporting a clinical assessment of this triplet combination in patients.

Han S ，Tushoski-Alemán GW ，Zhang P ，Zheng G ，Zhou D ，Huo Z ，Licht J ，George TJ ，Allegra C ，Trevino JG ，Hughes SJ ... -  《NEOPLASIA》

ADT-1004: a first-in-class, oral pan-RAS inhibitor with robust antitumor activity in preclinical models of pancreatic ductal adenocarcinoma.

Oncogenic KRAS mutations occur in nearly, 90% of patients with pancreatic ductal adenocarcinoma (PDAC). Targeting KRAS has been complicated by mutational heterogeneity and rapid resistance. We developed a novel pan-RAS inhibitor, ADT-1004 (an oral prodrug of ADT-007) and evaluated antitumor activity in murine and human PDAC models. Murine PDAC cells with KRASG12D mutation (KPC-luc or 2838c3-luc) were orthotopically implanted into the pancreas of C57BL/6J mice, and four PDX PDAC tumors with KRAS mutations were implanted subcutaneously in NSG mice. To assess potential to overcome RAS inhibitor resistance, parental and resistant MIA PaCa-2 PDAC cells (KRASG12C mutation) were implanted subcutaneously. Subcutaneously implanted RASWT BxPC-3 cells were used to assess the selectivity of ADT-1004. ADT-1004 potently blocked tumor growth and RAS activation in mouse PDAC models without discernable toxicity with target engagement and reduced activated RAS and ERK phosphorylation. In addition, ADT-1004 suppressed tumor growth in PDX PDAC models with KRASG12D, KRASG12V, KRASG12C, or KRASG13Q mutations and increased CD4+ and CD8+ T cells in the TME consistent with exhaustion and increased MHCII+ M1 macrophage and dendritic cells. ADT-1004 demonstrated superior efficacy over sotorasib and adagrasib in tumor models resistant to these KRASG12C inhibitors and MRTX1133 resistant KRASG12D mutant cells. As evidence of selectivity for tumors with mutant KRAS, ADT-1004 did not impact the growth of tumors from RASWT PDAC cells. ADT-1004 has strong antitumor activity in aggressive and clinically relevant PDAC models with unique selectivity to block RAS-mediated signaling in RAS mutant cells. As a pan-RAS inhibitor, ADT-1004 has broad activity and potential efficacy advantages over allele-specific KRAS inhibitors. These findings support clinical trials of ADT-1004 for KRAS mutant PDAC.

Bandi DSR ，Nagaraju GP ，Sarvesh S ，Carstens JL ，Foote JB ，Graff EC ，Fang YD ，Keeton AB ，Chen X ，Valiyaveettil J ，Berry KL ，Bae S ，Akce M ，Gorman G ，Yoon KJ ，Manne U ，Boyd MR ，Buchsbaum DJ ，Azmi AS ，Maxuitenko YY ，Piazza GA ，El-Rayes BF ... -  《Molecular Cancer》

Anticancer and therapeutic efficacy of XPO1 inhibition in pancreatic ductal adenocarcinoma through DNA damage and modulation of miR-193b/KRAS/LAMC2/ERK/AKT signaling cascade.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive and grave malignancies with confined and ineffective therapeutic options. XPO1 is a critical regulator of nuclear export and activation of tumor suppressor proteins. The present study evaluated the therapeutic potential and molecular mechanisms of XPO1 inhibition against PDAC. Firstly, we observed significant overexpression of XPO1 transcript in 179 PDAC patients than 171 normal pancreatic tissues in TCGA transcriptomic dataset. Higher XPO1 transcript levels displayed worse overall and disease-free survival. Further, we confirmed significant upregulation of XPO1 in a panel of PDAC cells. Eltanexor treatment resulted in significant inhibition of cell viability, clonogenic growth, migration, and epithelial-mesenchymal transition (EMT), along with the induction of cell cycle arrest. Mechanistically, eltanexor modulated the expression of key proteins including p21, p27, p53, cyclin B1, cyclin D1, c-Myc, N-cadherin, vimentin, E-cadherin associated with the cell viability, growth, cell cycle and EMT. Additionally, the eltanexor treatment resulted in marked increase in expression of γH2AX, and cleaved PARP, cleaved caspase-9 leading to induction of DNA damage and apoptosis of PDAC cells, respectively. Moreover, eltanexor treatment regulated the expression of key non-coding RNAs including miR193b, DINO, MALAT-1, H19, and SOX21-AS1 linked with tumorigenesis. Our results revealed a correlation among miR193b/KRAS/LAMC2, XPO1/KRAS, and LAMC2/KRAS. The findings also revealed that eltanexor treatment rescued the expression of miR193b which acts as a sponge for LAMC2 and KRAS resulting in the suppression of AKT/ERK downstream signaling cascade in PDAC. Interestingly, the combination of eltanexor with gemcitabine showed significant anticancer activity in PDAC cells. Altogether, our findings revealed the crucial role of XPO1 in modulating the expression of oncogenic proteins, ncRNAs, and DNA damage during PDAC progression as well as identified novel therapeutic miR-193b/KRAS/LAMC2/ERK/AKT axis.

Kirtonia A ，Pandya G ，Singh A ，Kumari R ，Singh B ，Kapoor S ，Khattar E ，Pandey AK ，Garg M ... -  《-》