Neratinib decreases pro-survival responses of [sorafenib + vorinostat] in pancreatic cancer

Phase 2 Study of Sorafenib, Valproic Acid, and Sildenafil in the Treatment of Recurrent High-Grade Glioma

Here we report the results of a single-center phase 2 clinical trial combining sorafenib tosylate, valproic acid, and sildenafil for the treatment of patients with recurrent high-grade glioma (NCT01817751). Clinical toxicities were grade 1 and grade 2, with one grade 3 toxicity for maculopapular rash (6.4%). For all evaluable patients, the median progression-free survival was 3.65 months and overall survival (OS) 10.0 months. There was promising evidence showing clinical activity and benefit. In the 33 evaluable patients, low protein levels of the chaperone GRP78 (HSPA5) was significantly associated with a better OS (p < 0.0026). A correlation between the expression of PDGFRα and OS approached significance (p < 0.0728). Five patients presently have a mean OS of 73.6 months and remain alive. This is the first therapeutic intervention glioblastoma trial to significantly associate GRP78 expression to OS. Our data suggest that the combination of sorafenib tosylate, valproic acid, and sildenafil requires additional clinical development in the recurrent glioma population.

Selective autophagy in cancer: mechanisms, therapeutic implications, and future perspectives

Eukaryotic cells engage in autophagy, an internal process of self-degradation through lysosomes. Autophagy can be classified as selective or non-selective depending on the way it chooses to degrade substrates. During the process of selective autophagy, damaged and/or redundant organelles like mitochondria, peroxisomes, ribosomes, endoplasmic reticulum (ER), lysosomes, nuclei, proteasomes, and lipid droplets are selectively recycled. Specific cargo is delivered to autophagosomes by specific receptors, isolated and engulfed. Selective autophagy dysfunction is closely linked with cancers, neurodegenerative diseases, metabolic disorders, heart failure, etc. Through reviewing latest research, this review summarized molecular markers and important signaling pathways for selective autophagy, and its significant role in cancers. Moreover, we conducted a comprehensive analysis of small-molecule compounds targeting selective autophagy for their potential application in anti-tumor therapy, elucidating the underlying mechanisms involved. This review aims to supply important scientific references and development directions for the biological mechanisms and drug discovery of anti-tumor targeting selective autophagy in the future.

Epigenetic control of pancreatic cancer metastasis

Surgical resection, when combined with chemotherapy, has been shown to significantly improve the survival rate of patients with pancreatic ductal adenocarcinoma (PDAC). However, this treatment option is only feasible for a fraction of patients, as more than 50% of cases are diagnosed with metastasis. The multifaceted process of metastasis is still not fully understood, but recent data suggest that transcriptional and epigenetic plasticity play significant roles. Interfering with epigenetic reprogramming can potentially control the adaptive processes responsible for metastatic progression and therapy resistance, thereby enhancing treatment responses and preventing recurrence. This review will focus on the relevance of histone-modifying enzymes in pancreatic cancer, specifically on their impact on the metastatic cascade. Additionally, it will also provide a brief update on the current clinical developments in epigenetic therapies.

Cellular responses after (neratinib plus pemetrexed) exposure in NSCLC cells

We previously demonstrated that neratinib interacted with pemetrexed to kill non-small cell lung cancer (NSCLC) cells. From developing other drug combinations, we observed that several days following exposure, cells activated survival mechanisms to counteract drug toxicity. The present studies attempted to define mechanisms that evolve to reduce the efficacy of neratinib and pemetrexed. Neratinib and pemetrexed synergized to kill NSCLC cells expressing wild-type RAS proteins, mutant KRAS (G12S; Q61H; G12A and G12C) or mutant NRAS (Q61K) or mutant ERBB1 (L858R; L858R T790M and exon 19 deletion). Neratinib and pemetrexed interacted in a greater than additive fashion to kill after 24 h, and after a further 24 h culture in the absence of drugs. Mutant KRAS G12V was more cytoprotective than either activated MEK1 or activated AKT. Knockdown of mutant KRAS reduced drug combination killing at the 48 h timepoint. Despite culture for 24 h in the absence of the drugs, the expression and activities of ERBB1, ERBB2 and ERBB4 remained significantly lower as did the activities of mammalian target of rapamycin (mTOR) C1 and mTORC2. The drug combination reduced KRAS and NRAS levels for 24 h, however, in the absence of the drugs, RAS levels had normalized by 48 h. Expression of Beclin1 and ATG5 remained elevated and of MCL1 and BCL-XL lower. No evolutionary activations of survival signaling by ERBB3, c-KIT, c-MET or PDGFRβ or in intracellular signaling pathways were observed. These findings argue against the development of 'early' resistance mechanisms after neratinib and pemetrexed exposure. Future studies will be required to understand how NSCLC cells become resistant to neratinib and pemetrexed.

A high-throughput Gaussia luciferase reporter assay for screening potential gasdermin E activators against pancreatic cancer

It is discovered that activated caspase-3 tends to induce apoptosis in gasdermin E (GSDME)-deficient cells, but pyroptosis in GSDME-sufficient cells. The high GSDME expression and apoptosis resistance of pancreatic ductal adenocarcinoma (PDAC) cells shed light on another attractive strategy for PDAC treatment by promoting pyroptosis. Here we report a hGLuc-hGSDME-PCA system for high-throughput screening of potential GSDME activators against PDAC. This screening system neatly quantifies the oligomerization of GSDME-N to characterize whether pyroptosis occurs under the stimulation of chemotherapy drugs. Based on this system, ponatinib and perifosine are screened out from the FDA-approved anti-cancer drug library containing 106 compounds. Concretely, they exhibit the most potent luminescent activity and cause drastic pyroptosis in PDAC cells. Further, we demonstrate that perifosine suppresses pancreatic cancer by promoting pyroptosis via caspase-3/GSDME pathway both in vitro and in vivo. Collectively, this study reveals the great significance of hGLuc-hGSDME-PCA in identifying compounds triggering GSDME-dependent pyroptosis and developing promising therapeutic agents for PDAC.

Neratinib as a Potential Therapeutic for Mutant RAS and Osimertinib-Resistant Tumours

Neratinib was developed as an irreversible catalytic inhibitor of ERBB2, which also acts to inhibit ERBB1 and ERBB4. Neratinib is U.S. Food and Drug Administration (FDA)-approved as a neo-adjuvant therapy for use in HER2+ breast cancer. More recently, chemical biology analyses and the authors’ own bench work have demonstrated that neratinib has additional targets, which open up the possibility of using the drug in cell types that either lack ERBB receptor family expression or who rely on survival signalling downstream of growth factor receptors. Neratinib rapidly disrupted mutant RAS nanoclustering, which was followed by mutant rat sarcoma virus proteins translocating via LC3-associated phagocytosis into the cytosol where they were degraded by macroautophagy. Neratinib catalytically inhibited the MAP4K mammalian STE20-like protein kinase 4 and also caused its degradation via macroautophagy. This resulted in ezrin dephosphorylation and the plasma membrane becoming flaccid. Neratinib disrupted the nanoclustering of RAC1, which was associated with dephosphorylation of PAK1 and Merlin, and with increased phosphorylation of the Merlin binding partners large tumour suppressor kinase 1/2, YAP, and TAZ. YAP and TAZ exited the nucleus. Neratinib retained its anti-tumour efficacy against NSCLC cells made resistant to either afatinib or to osimertinib. Collectively, these findings argue that the possibilities for the further development of neratinib as cancer therapeutic in malignancies that do not express or over-express members of the ERBB receptor family are potentially wide-ranging.

GZ17-6.02 and palbociclib interact to kill ER+ breast cancer cells

GZ17-6.02 is presently undergoing clinical evaluation in solid tumors and lymphoma. The present studies were performed to define its biology in estrogen receptor positive breast cancer cells and to determine whether it interacted with palbociclib to enhance tumor cell killing. GZ17-6.02 interacted in an additive fashion with palbociclib to kill ER+ breast cancer cells. GZ17-6.02 and palbociclib cooperated to inactivate mTOR and AKT and to activate ULK1 and PERK. The drugs interacted to increase the expression of FAS-L and BAX, and to decrease the levels of MCL1, the estrogen receptor, and HDACs 1–3. Palbociclib activated ERBB3, an effect blocked by GZ17-6.02. GZ17-6.02 and palbociclib interacted to increase the expression of multiple toxic BH3 domain proteins and to reduce MCL1 and BCL-XL expression. Knock down of FAS-L reduced the lethality of [GZ17-6.02 + palbociclib]. GZ17-6.02 and palbociclib interacted to enhance autophagosome formation and autophagic flux. Knock down of Beclin1, ATG5, BAG3, eIF2α, toxic BH3 domain proteins or CD95 significantly reduced drug combination lethality. GZ17-6.02 and palbociclib increased the expression of Beclin1 and ATG5, effects blocked by knock down of eIF2α. The drugs also increased the phosphorylation of the AMPK and ATG13, effects blocked by knock down of ATM. Knock down of ATM or the AMPK, or expression of activated mTOR significantly reduced the abilities of GZ17-6.02 and palbociclib to enhance autophagosome formation and autophagic flux.

Histone deacetylases: A novel class of therapeutic targets for pancreatic cancer

Pancreatic cancer is the seventh leading cause of cancer death worldwide, with a low 5-year survival rate. Novel agents are urgently necessary to treat the main pathological type, known as pancreatic ductal carcinoma (PDAC). The dysregulation of histone deacetylases (HDACs) has been identified in association with PDAC, which can be more easily targeted by small molecular inhibitors than gene mutations and may represent a therapeutic breakthrough for PDAC. However, the contributions of HDACs to PDAC remain controversial, and pharmacokinetic challenges have limited the application of HDAC inhibitors (HDACis) in PDAC. This review summarizes the mechanisms associated with success and failure of HDACis in PDAC and discusses the recent progress made in HDACi development and application, such as combination therapies designed to enhance efficacy. More precise strategies involving HDACis might eventually improve the outcomes of PDAC treatment.

Opportunities and challenges in targeted therapy and immunotherapy for pancreatic cancer

Pancreatic cancer is one of the most malignant tumours with a poor prognosis. In recent years, the incidence of pancreatic cancer is on the rise. Traditional chemotherapy and radiotherapy for pancreatic cancer have been improved, first-line and second-line palliative treatments have been developed, and adjuvant treatments have also been used in clinical. However, the 5-year survival rate is still less than 10% and new treatment methods such as targeted therapy and immunotherapy need to be investigated. In the past decades, many clinical trials of targeted therapies and immunotherapies for pancreatic cancer were launched and some of them showed an ideal prospect in a subgroup of pancreatic cancer patients. The experience of both success and failure of these clinical trials will be helpful to improve these therapies in the future. Therefore, the current research progress and challenges of selected targeted therapies and immunotherapies for pancreatic cancer are reviewed.

Pharmacological Targeting of Ferroptosis in Cancer Treatment

Ferroptosis is a non-apoptotic mode of Regulated Cell Death (RCD) driven by excessive accumulation of toxic lipid peroxides and iron overload. Ferroptosis could be triggered by inhibiting the antioxidant defense system and accumulating iron-dependent Reactive Oxygen Species (ROS) that react with polyunsaturated fatty acids in abundance. Emerging evidence over the past few years has revealed that ferroptosis is of great potential in inhibiting growth and metastasis and overcoming tumor cell resistance. Thus, targeting this form of cell death could be perceived as a potentially burgeoning approach in cancer treatment. This review briefly presents the underlying mechanisms of ferroptosis and further aims to discuss various types of existing drugs and natural compounds that could be potentially repurposed for targeting ferroptosis in tumor cells. This, in turn, will provide critical perspectives on future studies concerning ferroptosis-based cancer therapy.

Axitinib and HDAC Inhibitors Interact to Kill Sarcoma Cells

We have extended our analyses of HDAC inhibitor biology in sarcoma. The multi-kinase inhibitor axitinib interacted with multiple HDAC inhibitors to kill sarcoma cells. Axitinib and HDAC inhibitors interacted in a greater than additive fashion to inactivate AKT, mTORC1 and mTORC2, and to increase Raptor S722/S792 phosphorylation. Individually, all drugs increased phosphorylation of ATM S1981, AMPKα T172, ULK1 S317 and ATG13 S318 and reduced ULK1 S757 phosphorylation; this correlated with enhanced autophagic flux. Increased phosphorylation of ULK1 S317 and of Raptor S722/S792 required ATM-AMPK signaling. ULK1 S757 is a recognized site for mTORC1 and knock down of either ATM or AMPKα reduced the drug-induced dephosphorylation of this site. Combined exposure of cells to axitinib and an HDAC inhibitor significantly reduced the expression of HDAC1, HDAC2, HDAC3, HDAC4, HDAC6 and HDAC7. No response was observed for HDACs 10 and 11. Knock down of ULK1, Beclin1 or ATG5 prevented the decline in HDAC expression, as did expression of a constitutively active mTOR protein. Axitinib combined with HDAC inhibitors enhanced expression of Class I MHCA and reduced expression of PD-L1 which was recapitulated via knock down studies, particularly of HDACs 1 and 3. In vivo, axitinib and the HDAC inhibitor entinostat interacted to significantly reduce tumor growth. Collectively our findings support the exploration of axitinib and HDAC inhibitors being developed as a novel sarcoma therapy.

The development of multi-kinase inhibitors as pancreatic cancer therapeutics

Pancreatic cancer is an almost incurable malignancy whose incidence has increased over the past 30 years. Instead of pursuing the development of modalities utilizing 'traditional' cytotoxic chemotherapeutic agents, we have explored the possibilities of developing novel multi-kinase inhibitor drug combinations to kill this tumor type. Several approaches using the multi-kinase inhibitors sorafenib, regorafenib, and neratinib have been safely translated from the bench to the bedside, with objective anti-tumor responses. This review will discuss our prior preclinical and clinical studies and discuss future clinical opportunities in this disease.

Osimertinib-resistant NSCLC cells activate ERBB2 and YAP/TAZ and are killed by neratinib

We performed additional mechanistic analyses to redefine neratinib biology and determined the mechanisms by which the multi-kinase inhibitor neratinib interacted with the thymidylate synthase inhibitor pemetrexed to kill NSCLC cells expressing either mutant KRAS (G12S; Q61H; G12A; G12C) or mutant NRAS (Q61K) or mutant ERBB1 (L858R; L858R T790M; exon 19 deletion). Neratinib rapidly reduced KRASG12V and RAC1G12V nanoclustering which was followed by KRASG12V, but not RAC1G12V, being extensively mislocalized away from the plasma membrane. This correlated with reduced levels of, and reorganized membrane localization of phosphatidylserine and cholesterol. Reduced nanoclustering was not associated with inactivation of ERBB1, Merlin or Ezrin. The drug combination killed cells expressing mutant KRAS, NRAS or mutant ERBB1 proteins. Afatinib or osimertinib resistant cells were killed with a similar efficacy to non-resistant cells. Compared to osimertinib-resistant cells, sensitive cells had less ERBB2 Y1248 phosphorylation. In osimertinib resistant H1975 cells, the drug combination was less capable of inactivating AKT, mTOR, STAT3, STAT5, ERK1/2 whereas it gained the ability to inactivate ERBB3. In resistant H1650 cells, the drug combination was less capable of inactivating JAK2 and STAT5. Sensitive cells exhibited elevated basal phosphorylation of YAP and TAZ. In resistant cells, portions of YAP and TAZ were localized in the nucleus. [Neratinib + pemetrexed] increased phosphorylation of YAP and TAZ, caused their nuclear exit, and enhanced ERBB2 degradation. Thus, neratinib targets an unidentified protein whose functional inhibition directly results in RAS inactivation and tumor cell killing. Our data prove that, albeit indirectly, oncogenic RAS proteins are druggable by neratinib.

Oxidative Stress Activated by Sorafenib Alters the Temozolomide Sensitivity of Human Glioma Cells Through Autophagy and JAK2/STAT3-AIF Axis

The development of temozolomide (TMZ) resistance in glioma leads to poor patient prognosis. Sorafenib, a novel diaryl urea compound and multikinase inhibitor, has the ability to effectively cross the blood-brain barrier. However, the effect of sorafenib on glioma cells and the molecular mechanism underlying the ability of sorafenib to enhance the antitumor effects of TMZ remain elusive. Here, we found that sorafenib could enhance the cytotoxic effects of TMZ in glioma cells in vitro and in vivo. Mechanistically, the combination of sorafenib and TMZ induced mitochondrial depolarization and apoptosis inducing factor (AIF) translocation from mitochondria to nuclei, and this process was dependent on STAT3 inhibition. Moreover, the combination of sorafenib and TMZ inhibited JAK2/STAT3 phosphorylation and STAT3 translocation to mitochondria. Inhibition of STAT3 activation promoted the autophagy-associated apoptosis induced by the combination of sorafenib and TMZ. Furthermore, the combined sorafenib and TMZ treatment induced oxidative stress while reactive oxygen species (ROS) clearance reversed the treatment-induced inhibition of JAK2/STAT3. The results indicate that sorafenib enhanced the temozolomide sensitivity of human glioma cells by inducing oxidative stress-mediated autophagy and JAK2/STAT3-AIF axis.

Novel small molecule inhibitors of the transcription factor ETS-1 and their antitumor activity against hepatocellular carcinoma

The transcription factor ETS-1 (E26 transformation specific sequence 1) is the key regulator for malignant tumor cell proliferation and invasion by mediating the transcription of the invasion/migration related factors, e.g. MMPs (matrix metalloproteinases). This work aims to identify the novel small molecule inhibitors of ETS-1 using a small molecule compound library and to study the inhibitors' antitumor activity against hepatocellular carcinoma (HCC). The luciferase reporter is used to examine the inhibition and activation of ETS-1's transcription factor activity in HCC cells, including a highly invasive HCC cell line, MHCC97-H, and five lines of patient-derived cells. The inhibition of the proliferation of HCC cells is examined using the MTT assay, while the invasion of HCC cells is examined using the transwell assay. The anti-tumor activity of the selected compound on HCC cells is also examined in a subcutaneous tumor model or intrahepatic tumor model in nude mice. The results show that for the first time, four compounds, EI1~EI-4, can inhibit the transcription factor activation of ETS-1 and the proliferation or invasion of HCC cells. Among the four compounds, EI-4 has the best activation. The results from this paper contribute to expanding our understanding of ETS-1 and provide alternative, the safer and more effective, HCC molecular therapy strategies.