Deciphering cellular plasticity in pancreatic cancer for effective treatments

Cellular plasticity and therapy resistance are critical features of pancreatic cancer, a highly aggressive and fatal disease. The pancreas, a vital organ that produces digestive enzymes and hormones, is often affected by two main types of cancer: the pre-dominant ductal adenocarcinoma and the less common neuroendocrine tumors. These cancers are difficult to treat due to their complex biology characterized by cellular plasticity leading to therapy resistance. Cellular plasticity refers to the capability of cancer cells to change and adapt to different microenvironments within the body which includes acinar-ductal metaplasia, epithelial to mesenchymal/epigenetic/metabolic plasticity, as well as stemness. This plasticity allows heterogeneity of cancer cells, metastasis, and evasion of host's immune system and develops resistance to radiation, chemotherapy, and targeted therapy. To overcome this resistance, extensive research is ongoing exploring the intrinsic and extrinsic factors through cellular reprogramming, chemosensitization, targeting metabolic, key survival pathways, etc. In this review, we discussed the mechanisms of cellular plasticity involving cellular adaptation and tumor microenvironment and provided a comprehensive understanding of its role in therapy resistance and ways to overcome it.

Individual ingredients of NP-101 (Thymoquinone formula) inhibit SARS-CoV-2 pseudovirus infection

Thymoquinone TQ, an active ingredient of Nigella Sativa, has been shown to inhibit COVID-19 symptoms in clinical trials. Thymoquinone Formulation (TQF or NP-101) is developed as a novel enteric-coated medication derivative from Nigella Sativa. TQF consists of TQ with a favorable concentration and fatty acids, including palmitic, oleic, and linoleic acids. In this study, we aimed to investigate the roles of individual ingredients of TQF on infection of SARS-CoV-2 variants in-vitro, by utilizing Murine Leukemia Virus (MLV) based pseudovirus particles. We demonstrated that NP-101, TQ, and other individual ingredients, including oleic, linoleic, and palmitic acids inhibited SARS-CoV-2 infection in the MLV-based pseudovirus model. A large, randomized phase 2 study of NP-101 is planned in outpatient COVID-19 patients.

Regulator of Chromosome Condensation (RCC1) a novel therapeutic target in pancreatic ductal adenocarcinoma drives tumor progression via the c-Myc-RCC1-Ran axis

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy with limited therapeutic options. Here we for the first time evaluated the role of regulator of chromosome condensation 1 (RCC1) in PDAC subsistence and drug resistance. RCC1 expression was found to be elevated in PDAC tissues in comparison with normal pancreatic tissues and was linked to poor prognosis. RCC1 silencing in a panel of PDAC cells by RNA interference and CRISPR-Cas9 resulted in reduced cellular proliferation in 2D and 3D cultures. RCC1 KD reduced migratory and clonogenic ability, enhanced apoptosis, and altered cell cycle distribution in human PDAC cells as well as cells isolated from the LSL-Kras G12D/+; LSL-Trp53 R172H/+ ;Pdx1-Cre (KPC) mouse tumors. Subcutaneous cell-derived xenografts show significantly attenuated growth of RCC1 KO tumors. Mechanistically, RCC1 knockdown resulted in disruption of subcellular Ran distribution indicating that stable nuclear Ran localization is critical for PDAC proliferation. Nuclear and cytosolic proteomic analysis revealed altered subcellular proteome in RCC1 KD KPC-tumor-derived cells. Altered cytoplasmic protein pathways include several metabolic pathways and PI3K-Akt signaling pathway. Pathways enriched in altered nuclear proteins include cell cycle, mitosis, and RNA regulation. RNA sequencing of RCC1 KO cells showed widespread transcriptional alterations. Upstream of RCC1, c-Myc activates the RCC1-Ran axis, and RCC1 KO enhances the sensitivity of PDAC cells to c-Myc inhibitors. Finally, RCC1 knockdown resulted in the sensitization of PDAC cells to Gemcitabine. Our results indicate that RCC1 is a potential therapeutic target in PDAC that warrants further clinical investigations.

Molecular analysis of XPO1 inhibitor and gemcitabine-nab-paclitaxel combination in KPC pancreatic cancer mouse model

BACKGROUND

The majority of pancreatic ductal adenocarcinoma (PDAC) patients experience disease progression while on treatment with gemcitabine and nanoparticle albumin-bound (nab)-paclitaxel (GemPac) necessitating the need for a more effective treatment strategy for this refractory disease. Previously, we have demonstrated that nuclear exporter protein exportin 1 (XPO1) is a valid therapeutic target in PDAC, and the selective inhibitor of nuclear export selinexor (Sel) synergistically enhances the efficacy of GemPac in pancreatic cancer cells, spheroids and patient-derived tumours, and had promising activity in a phase I study.

METHODS

Here, we investigated the impact of selinexor-gemcitabine-nab-paclitaxel (Sel-GemPac) combination on LSL-KrasG12D/+ ; LSL-Trp53R172H/+ ; Pdx1-Cre (KPC) mouse model utilising digital spatial profiling (DSP) and single nuclear RNA sequencing (snRNAseq).

RESULTS

Sel-GemPac synergistically inhibited the growth of the KPC tumour-derived cell line. The Sel-GemPac combination reduced the 2D colony formation and 3D spheroid formation. In the KPC mouse model, at a sub-maximum tolerated dose (sub-MTD) , Sel-GemPac enhanced the survival of treated mice compared to controls (p < .05). Immunohistochemical analysis of residual KPC tumours showed re-organisation of tumour stromal architecture, suppression of proliferation and nuclear retention of tumour suppressors, such as Forkhead Box O3a (FOXO3a). DSP revealed the downregulation of tumour promoting genes such as chitinase-like protein 3 (CHIL3/CHI3L3/YM1) and multiple pathways including phosphatidylinositol 3'-kinase-Akt (PI3K-AKT) signalling. The snRNAseq demonstrated a significant loss of cellular clusters in the Sel-GemPac-treated mice tumours including the CD44+ stem cell population.

CONCLUSION

Taken together, these results demonstrate that the Sel-GemPac treatment caused broad perturbation of PDAC-supporting signalling networks in the KPC mouse model.

HIGHLIGHTS

The majority of pancreatic ductal adenocarcinoma (PDAC) patients experience disease progression while on treatment with gemcitabine and nanoparticle albumin-bound (nab)-paclitaxel (GemPac). Exporter protein exportin 1 (XPO1) inhibitor selinexor (Sel) with GemPac synergistically inhibited the growth of LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx1-Cre (KPC) mouse derived cell line and enhanced the survival of mice. Digital spatial profiling shows that Sel-GemPac causes broad perturbation of PDAC-supporting signalling in the KPC model.

Anticancer Efficacy of KRASG12C Inhibitors Is Potentiated by PAK4 Inhibitor KPT9274 in Preclinical Models of KRASG12C-Mutant Pancreatic and Lung Cancers

KRASG12C inhibitors, such as sotorasib and adagrasib, have revolutionized cancer treatment for patients with KRASG12C-mutant tumors. However, patients receiving these agents as monotherapy often develop drug resistance. To address this issue, we evaluated the combination of the PAK4 inhibitor KPT9274 and KRASG12C inhibitors in preclinical models of pancreatic ductal adenocarcinoma (PDAC) and non-small cell lung cancer (NSCLC). PAK4 is a hub molecule that links several major signaling pathways and is known for its tumorigenic role in mutant Ras-driven cancers. We found that cancer cells resistant to KRASG12C inhibitor were sensitive to KPT9274-induced growth inhibition. Furthermore, KPT9274 synergized with sotorasib and adagrasib to inhibit the growth of KRASG12C-mutant cancer cells and reduce their clonogenic potential. Mechanistically, this combination suppressed cell growth signaling and downregulated cell-cycle markers. In a PDAC cell line-derived xenograft (CDX) model, the combination of a suboptimal dose of KPT9274 with sotorasib significantly reduced the tumor burden (P= 0.002). Similarly, potent antitumor efficacy was observed in an NSCLC CDX model, in which KPT9274, given as maintenance therapy, prevented tumor relapse following the discontinuation of sotorasib treatment (P= 0.0001). Moreover, the combination of KPT9274 and sotorasib enhances survival. In conclusion, this is the first study to demonstrate that KRASG12C inhibitors can synergize with the PAK4 inhibitor KPT9274 and combining KRASG12C inhibitors with KPT9274 can lead to remarkably enhanced antitumor activity and survival benefits, providing a novel combination therapy for patients with cancer who do not respond or develop resistance to KRASG12C inhibitor treatment.

Hepatocellular Carcinoma: Surveillance, Diagnosis, Evaluation and Management

Hepatocellular carcinoma (HCC) ranks fourth in cancer-related deaths worldwide. Semiannual surveillance of the disease for patients with cirrhosis or hepatitis B virus allows for early detection with more favorable outcomes. The current underuse of surveillance programs demonstrates the need for intervention at both the patient and provider level. Mail outreach along with navigation provision has proven to increase surveillance follow-up in patients, while provider-targeted electronic medical record reminders and compliance reports have increased provider awareness of HCC surveillance. Imaging is the primary mode of diagnosis in HCC with The Liver Imaging Reporting and Data System (LI-RADS) being a widely accepted comprehensive system that standardizes the reporting and data collection for HCC. The management of HCC is complex and requires multidisciplinary team evaluation of each patient based on their preference, the state of the disease, and the available medical and surgical interventions. Staging systems are useful in determining the appropriate intervention for HCC. Early-stage HCC is best managed by curative treatment modalities, such as liver resection, transplant, or ablation. For intermediate stages of the disease, transarterial local regional therapies can be applied. Advanced stages of the disease are treated with systemic therapies, for which there have been recent advances with new drug combinations. Previously sorafenib was the mainstay systemic treatment, but the recent introduction of atezolizumab plus bevacizumab proves to have a greater impact on overall survival. Although there is a current lack of improved outcomes in Phase III trials, neoadjuvant therapies are a potential avenue for HCC management in the future.

Anticancer efficacy of KRASG12C inhibitors is potentiated by PAK4 inhibitor KPT9274 in preclinical models of KRASG12C mutant pancreatic and lung cancers

KRASG12C inhibitors have revolutionized the treatment landscape for cancer patients harboring the G12C mutant isoform of KRAS. With the recent FDA approval of sotorasib and adagrasib, patients now have access to more promising treatment options. However, patients who receive these agents as a monotherapy usually develop drug resistance. Thus, there is a need to develop logical combination strategies that can delay or prevent the onset of resistance and simultaneously enhance the antitumor effectiveness of the treatment regimen. In this study, we aimed at pharmacologically targeting PAK4 by KPT9274 in combination with KRASG12C inhibitors in KRASG12C mutant pancreatic ductal adenocarcinoma (PDAC) and nonâ€"small cell lung cancer (NSCLC) preclinical models. PAK4 is a hub molecule that links several major signaling pathways and is known for its tumorigenic role in mutant Ras-driven cancers. We assessed the cytotoxicity of PAK4 and KRASG12C inhibitors combination in KRASG12C mutant 2D and 3D cellular models. KPT9274 synergized with both sotorasib and adagrasib in inhibiting the growth of KRASG12C mutant cancer cells. The combination was able to reduce the clonogenic potential of KRASG12C mutant PDAC cells. We also evaluated the antitumor activity of the combination in a KRASG12C mutant PDAC cell line-derived xenograft (CDX) model. Oral administration of a sub-optimal dose of KPT9274 in combination with sotorasib (at one-fourth of MTD) demonstrated significant inhibition of the tumor burden ( p = 0.002). Similarly, potent antitumor efficacy was observed in an NSCLC CDX model where KPT9274, acting as an adjuvant, prevented tumor relapse following the discontinuation of sotorasib treatment ( p = 0.0001). KPT9274 and sotorasib combination also resulted in enhanced survival. This is the first study showing that KRASG12C inhibitors can synergize with PAK4 inhibitor KPT9274 both in vitro and in vivo resulting in remarkably enhanced antitumor activity and survival outcomes.

Significance

KRASG12C inhibitors demonstrate limited durable response in patients with KRASG12C mutations. In this study, combining PAK4 inhibitor KPT9274 with KRASG12C inhibitors has resulted in potent antitumor effects in preclinical cancer models of PDAC and NSCLC. Our results bring forward a novel combination therapy for cancer patients that do not respond or develop resistance to KRASG12C inhibitor treatment.

Molecular characterization and clinical outcomes of pancreatic neuroendocrine tumors (pNENs) harboring PAK4-NAMPT alterations

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Background: The mTOR inhibitor, Everolimus (EVE), is FDA-approved for the treatment of advanced PNENs on the basis of delay of progression. The RADIANT-3 trial showed an increase in PFS from 4.6 to 11 months compared to placebo with an ORR of only 5%. Prior studies suggest that targeting the aberrant expression of mTOR regulators p21 activated kinase 4 (PAK4) and nicotinamide adenine dinucleotide biosynthesis enzyme nicotinamide phosphoribosyltransferase (NAMPT) in PNENs sensitizes these tumors to EVE. To further qualify these observations, we queried a large real-world dataset of PNENs, characterizing the molecular and immune landscapes, as well as the clinical outcomes associated with aberrant PAK4 and NAMPT expression. Methods: 294 cases of PNENs were analyzed using Next Generation Sequencing (NextSeq) and Whole Exome and Whole Transcriptome Sequencing (NovaSeq) at Caris Life Sciences (Phoenix, AZ). For our analyses, we stratified our study cohort into four groups based on the median expression of PAK4 and NAMPT: PAK4-low/NAMPT-low, PAK4-low/NAMPT-high, PAK4-high/NAMPT-low and PAK4-high/NAMPT-high. Significance was determined using chi-square, Fisher-Exact or Mann-Whitney U, and p-values were adjusted for multiple comparisons (q < 0.05). Results: High prevalence of mutations in PTEN (10.71% vs 1.18%; p < 0.05, q > 0.05), a tumor suppressor of the mTOR pathway and high expression of genes activated in response to mTOR activation such as SLC2A1 (3.07-fold), PFKP (3.32-fold), SCD (2.70-fold), MVK (2.92-fold) and G6PD (2.58-fold) were observed in PAK4-high/NAMPT-high compared to the PAK4-low/NAMPT-low tumors (all q < 0.05). A congruent enrichment of PI3K/AKT/mTOR and glycolysis pathways by single-sample gene set enrichment analysis was observed in these tumors (all q < 0.05). When querying the immune landscape, we observed enrichment in inflammatory response, IL6/JAK/STAT3, IL2/STAT5 signaling pathways and immune checkpoint genes such as PDCD1 (5.14-fold), CD274 (2.84-fold), PDCD1LG2 (2.44-fold), CD80 (3.00-fold), CD86 (2.82-fold), IDO1 (1.92-fold), LAG3 (3.09-fold), HAVCR2 (2.66-fold) and CTLA4 (4.49-fold) in the PAK4-high/NAMPT-high tumors (all q < 0.05). Immune cell infiltration estimates revealed an increase in Neutrophils, NK cells and Tregs in the PAK4-high/NAMPT-high tumors (p < 0.05, q > 0.05). Conclusions: Our study demonstrates that PAK4-high/NAMPT-high PNENs are associated with distinct molecular and immune profiles. While the dual blockade of PAK4 and NAMPT has been reported to enhance the efficacy of EVE in PNENs, whether such a blockade would enhance the efficacy of immunotherapeutics warrants further investigation.

A phase I study of CPI-613 (devimistat) in combination with chemoradiation in patients with pancreatic adenocarcinoma

TPS760

Background: Local tumor progression is a cause of significant mortality and morbidity in patients with unresectable pancreatic ductal adenocarcinoma (PDAC). Effective approaches to achieve durable local control are urgently needed. Metabolic reprogramming and enhanced mitochondrial function, both hallmarks of PDAC, are known contributors to chemo- and radio-resistance. CPI-613, a lipoic acid analog that selectively inhibits components of the Krebs cycle in tumors, showed promising preclinical synergy in combination with gemcitabine and radiation therapy (gem-RT). Methods: We describe a single-arm, single-center, open-label, phase I study designed to determine the maximum tolerated dose of CPI-613 when used concomitantly with gemcitabine and intensity modulated radiation therapy (IMRT) for local control of PDAC. CPI-613 will be administered once weekly by intravenous infusion over approximately 2 hours at a starting dose of 500 mg/m2 and dose-escalated/de-escalated using a Bayesian optimal interval design. Gemcitabine will be given once weekly at 400 mg/m2 dosage and IMRT as 54 Gray (Gy) in 30 fractions (1.8 Gy per fraction) with five fractions given per week. Up to 24 patients will be enrolled for the study after meeting the following main eligibility criteria, which include: pathologically confirmed PDAC; inoperable disease that by institutional pancreatic multidisciplinary tumor board or multidisciplinary review are considered to benefit from definitive local control of the primary tumor; ECOG of 0-2; and adequate organ and marrow function after completion of intended systemic chemotherapy. The secondary objectives are to determine the recommended phase II dose of CPI-613 when used with gem-RT, safety and tolerability of CPI-613-gem-RT, overall survival, local progression-free survival (PFS), overall PFS, patient-reported quality of life after treatment, and late gastrointestinal toxicities following treatment with CPI-613-gem-RT. Clinical trial information: NCT05325281 . Support: Cornerstone Pharmaceuticals. [Table: see text]

Role of noncoding RNAs in pancreatic ductal adenocarcinoma associated cachexia

Cachexia is an acute syndrome that is very commonly observed in patients with cancer. Cachexia is the number one cause of death in patients with metastatic disease and is also the major factor for physical toxicity and financial burden. More importantly, the majority of patients with advanced-stage pancreatic ductal adenocarcinoma (PDAC) cancer undergo cachexia. Pancreatic cancer causes deaths of ∼50,000 Americans and about 400,000 people worldwide every year. The high mortality rates in metastatic PDAC are due to systemic pathologies and cachexia, which quickens death in these patients. About 90% of all patients with PDAC undergo wasting of muscle causing mobility loss and leading to a number of additional pathological conditions. PDAC-associated cancer cachexia emanates from complex signaling cues involving both mechanical and biological signals. Tumor invasion is associated with the loss of pancreatic function-induced digestive disorders and malabsorption, which causes subsequent weight loss and eventually promotes cachexia. Besides, systemic inflammation of patients with PDAC could release chemical cues (e.g., cytokine-mediated Atrogin-1/MAFbx expression) that participate in muscle wasting. Our understanding of genes, proteins, and cytokines involved in promoting cancer cachexia has evolved considerably. However, the role of epigenetic factors, particularly the role of noncoding RNAs (ncRNAs) in regulating PDAC-associated cachexia is less studied. In this review article, the most updated knowledge on the various ncRNAs including microRNAs (miRs), long noncoding RNA (lncRNAs), piwi interacting RNAs (PiwiRNAs), small nucleolar RNA (snoRNAs), and circular RNAs (circRNA) and their roles in cancer cachexia are described.

KRAS G12D targeted therapies for pancreatic cancer: Has the fortress been conquered?

KRAS mutations are among the most commonly occurring mutations in cancer. After being deemed undruggable for decades, KRAS G12C specific inhibitors showed that small molecule inhibitors can be developed against this notorious target. At the same time, there is still no agent that could target KRAS G12D which is the most common KRAS mutation and is found in the majority of KRAS-mutated pancreatic tumors. Nevertheless, significant progress is now being made in the G12D space with the development of several compounds that can bind to and inhibit KRAS G12D, most notably MRTX1133. Exciting advances in this field also include an immunotherapeutic approach that uses adoptive T-cell transfer to specifically target G12D in pancreatic cancer. In this mini-review, we discuss recent advances in KRAS G12D targeting and the potential for further clinical development of the various approaches.

Thymoquinone Plus Immunotherapy in Extra-Pulmonary Neuroendocrine Carcinoma: Case Series for a Novel Combination

BACKGROUND

Neuroendocrine neoplasms (NENs) are a heterogeneous group of cancers that had a significant increase in annual incidence in the last decade. They can be divided into well-differentiated neuroendocrine tumors (NETs) and poorly differentiated neuroendocrine carcinomas (NECs). Poorly differentiated NECs are aggressive forms of cancers with limited therapeutic options. The first line treatment of metastatic poorly differentiated NECs is similar to small cell lung cancer, with cytotoxic chemotherapy (etoposide plus platinum). Patients who progress have limited therapeutic options and poor overall survival, calling for other novel agents to combat this deadly disease. Therefore, in this article, we summarized the effects of a novel component, Thymoquinone (TQ, C10H12O2), which is the main bioactive component of the black seed (Nigella sativa, Ranunculaceae family), plus immunotherapy in case series of patients with refractory metastatic extra-pulmonary NEC (EP-NEC) and one case of mixed neuroendocrine-non-neuroendocrine neoplasm (MiNEN).

METHODS

We report the effect of TQ plus dual immune checkpoint inhibitors (nivolumab plus ipilimumab) in four patients with poorly differentiated gastrointestinal Ep-NEC and MiNEN who progressed on cytotoxic chemotherapy.

RESULTS

This is the first case series to report the clinical activity of TQ plus dual immune checkpoint inhibitors (nivolumab plus ipilimumab) in patients with refractory metastatic EP-NEC. The four patients showed benefits with the combined regimen TQ plus dual ICPIs with durable response and exceeded the two years of progression-free survival. None of the four patients experienced significant toxicity, and all of them showed improvement in quality of life.

CONCLUSION

The reported clinical courses suggest that combined TQ plus ICPIs is a potential promising regimen for refractory EP-NEC and MiNEN that deserves further prospective investigation.

Deregulated transcription factors and poor clinical outcomes in cancer patients

Transcription factors are a group of proteins, which possess DNA-binding domains, bind to DNA strands of promoters or enhancers, and initiate transcription of genes with cooperation of RNA polymerase and other co-factors. They play crucial roles in regulating transcription during embryogenesis and development. Their physiological status in different cell types is also important to maintain cellular homeostasis. Therefore, any deregulation of transcription factors will lead to the development of cancer cells and tumor progression. Based on their functions in cancer cells, transcription factors could be either oncogenic or tumor suppressive. Furthermore, transcription factors have been shown to modulate cancer stem cells, epithelial-mesenchymal transition (EMT) and drug response; therefore, measuring deregulated transcription factors is hypothesized to predict treatment outcomes of patients with cancers and targeting deregulated transcription factors could be an encouraging strategy for cancer therapy. Here, we summarize the current knowledge of major deregulated transcription factors and their effects on causing poor clinical outcome of patients with cancer. The information presented here will help to predict the prognosis and drug response and to design novel drugs and therapeutic strategies for the treatment of cancers by targeting deregulated transcription factors.

Abstract 5330: Nuclear protein export inhibitor selinexor chemotherapy combination for pancreatic cancer therapy

Background: The majority of pancreatic ductal adenocarcinoma (PDAC) patients experience disease progression after Gemcitabine-nab-Paclitaxel (GemPac) treatment indicating the need for more effective combination therapies for this highly recalcitrant disease. Earlier we showed that nuclear exporter protein exportin 1 (XPO1) is a valid therapeutic target in PDAC and selective inhibitor of nuclear export (SINE) selinexor (Sel), synergistically enhances the efficacy of GemPac in pancreatic cancer cells, spheroids, patient derived tumors and showed evaluable response in PDAC patients in a Phase I study. Here we investigated the mechanisms of this synergy utilizing PDAC cellular models in vitro and LSL-Kras G12D/+; Trp53 fl/+; Pdx1-Cre (KPC) mouse model.

Methods: We used single-nuclei RNA sequencing in KPC tumors, and poly A RNA sequencing in PDAC cells post sel-Gem-Pac treatment. Prioritized sn-seq and RNA-seq identified molecules were validated in in vitro or in the PDAC patient samples through siRNA mediated silencing, quantitative gene expression, cytotoxicity and related assays.

Results: In KPC model, selinexor-GemPac caused statistically significant enhancement in survival compared to controls (p less than 0.05). Molecular analysis of residual KPC tumors showed re-organization of tumor stromal architecture, suppression of proliferation and nuclear retention of tumor suppressors. Histopathological analysis for Ki67 suggests comparatively lower rate of proliferation and enhanced nuclear accumulation of FOXO3a in the treated mice. Loosening of stroma and lowering of collagen fiber is also evident in treated mice from Picrosirius and Masson’s trichrome staining. Additionally, the KPC derived primary tumor cells showed reduced colony formation upon combination treatment. Sn-seq showed reduction in tumor cell heterogeneity (less cell clusters based on gene expression), CDK8, CD44 and Camk1d stem cell and EMT related genes alongside significant alterations in mitochondrial signaling after combination treatment. In cellular models, GO and GSEA analyses of RNA-seq data predicted DNA templated regulation of transcription and DNA replication associated genes in Sel or Sel-GemPac mediated growth inhibition. The top downregulated genes including drug resistant related gene PFN1 and HSP90 identified in Sel or Sel-GemPac treated PDAC cells from RNA-seq data were validated using RNAi and confirmed their role in synergy.

Conclusions: Taken together Selinexor in combination with Gemcitabine-nab-Paclitaxel enhanced the survival of KPC mice through inhibition of well-connected tumor promoting molecules resulting in broad penetration in PDAC supporting signaling. A phase II study involving selinexor-gemcitabine combination in patients with metastatic PDAC is ongoing.

Citation Format: Md. Hafiz Uddin, Sahar Bannoura, Yiwei Li, Husain Y. Khan, Amro Aboukameel, Mohammed N. Al-Hallak, Rafic Beydoun, Steve Kim, Yosef Landesman, Ramzi M. Mohammad, Anthony Shields, Asfar S. Azmi. Nuclear protein export inhibitor selinexor chemotherapy combination for pancreatic cancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5330.

Abstract 5832: Utilizing small noncoding RNAs as biomarkers for selinexor treatment in gastric cancer

Gastric cancer is a deadly disease with a low 5-year survival rate of 32%. This disease is characterized by high rates of chemo resistance and late initial detection. We have previously reported that inhibition of nuclear exporter protein Exportin 1 (XPO1/CRM1) with the small molecule inhibitor selinexor (KPT-330) is a viable therapeutic approach in gastric cancer. Inhibition of XPO1 blocks proliferation and suppresses tumor growth through nuclear retention of tumor suppressor proteins such as TP53. Besides nuclear retention, we also demonstrated that XPO1 inhibition leads to a perturbation of cancer specific microRNAs including microRNA-7974 downregulation (miR-7974) and microRNA-129-1-3p upregulation (miR-129-1-3p) within a small RNA sequencing study. In this study we evaluated the role of these microRNAs in gastric cancer perpetuation in respect to their naive functions in five distinct subtypes of gastric cancer. Our results show over-expression of miR-7974 and loss of miR-129-1-3p promotes gastric cancer growth and progression, based on specific subtype of disease. We have further found that the differential expression of these microRNAs leads to gastric cancer cellular changes including cell cycle alterations, upregulation of autophagy processes, chemoresistance and alterations in the cellular framework leading to more invasive phenotypes. Validation with normal gastric epithelial cells revealed these microRNAs are relevant as they are perturbed in gastric cancer as well as the proteins in which they modulate. Finally, we have validated treatment of gastric cancer cells with the XPO1 inhibitor selinexor altered the expression of miR-7974 and miR-129-1-3p differently, based on subtype, as we have previously observed in small RNA sequencing screen, leading to a reversal of the pro-cancerous phenotypes previously observed. In vivo investigation is currently ongoing to identify whether we can capture either miR-7974 or miR-129-1-3p within the serum as further evidence of microRNA perturbation as a predictive biomarker for selinexor efficacy.

Citation Format: Rachel E. Sexton, Amro Aboukameel, Yiwei Li, Husain Y. Khan, Md Hafiz Uddin, Trishyan Kashyap, Yosef Landesman, Anteneh Tesfaye, Asfar S. Azmi. Utilizing small noncoding RNAs as biomarkers for selinexor treatment in gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5832.

Experience with 177Lu-Dotatate in patients with metastatic gastroenteropancreatic neuroendocrine tumors (GEP-NET): Report from a single urban cancer center

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Background:177Lu-Dotatate is FDA approved for advanced well differentiated (WD) midgut neuroendocrine tumors (NETs). However, questions remain about tolerability and efficacy in patients (pts) with higher grade disease, more than one prior line of treatment, and in non-ileal primaries. Methods: This is a retrospective analysis of pts with histologically proven WD metastatic GEP-NETs who received 177Lu-Dotatate at a single racially diverse urban cancer center. Patients had disease that progressed on systemic therapy that included somatostatin analog (SSA), and radiotracer uptake at disease sites using 68Gallium-Dotate PET/CT. ECOG performance score (PS) was 0 to 2. 177Lu-Dotatate was administered in 200 mCi doses every 8 weeks for a total of 4 cycles and a maximum of 800 mCi. Patients were followed with serial CT scan and/or abdominal MRI with best objective response per RECIST criteria. Results: Fifty-one pts were treated between December 2017 and August 2021. Thirty-eight pts completed a minimum 3-month follow-up imaging. Median age was 64 years, 59% were female, 66% identified as white, 26% as Black, 8% as other. Most frequent primary sites were small intestine (64%) and. All had metastatic disease involving the liver except for one pt. Median time from diagnosis to 177Lu-Dotatate was 51 months (3-201). CTCAE grade 3/4 hematologic toxicity was seen in 6 of 51 pts (12%). Grade 3/4 thrombocytopenia occurred in 3 pts, grade 3/4 leukopenia occurred in 2 pts and grade 3 anemia occurred in 1 pt. A single pt developed myelodysplastic syndrome 1 year after 177Lu-Dotatate. Non-white pts had significantly higher risk of grade 1 elevated creatinine at 38% vs 6% in those who identified as white (p = 0.015). Of the 37 pts who reached 3-month follow-up, 27% had partial response, 43% had a mixed/stable response, and 30% had progressive disease. Only gender demonstrated significant difference; with male gender associated with worse response categories (p = 0.001). Median OS was 3.09 years. Metastatic disease in the liver only was associated with significantly worse OS (p = 0.015) compared to liver and other tissues. The median PFS was 1.36 years. Metastatic disease in the liver only was associated with significantly worse PFS (p = 0.043). Higher tumor grade neared significant association with worse PFS (p = 0.053). There was no difference in PFS by race, primary tumor site (pancreatic vs small bowel), PS, prior treatment history or time to first 177Lu-Dotatate. Conclusions: Diverse patients with WD GEP-NETs treated at this single urban cancer center with 177Lu-Dotatate demonstrated acceptable toxicity. Median PFS and OS were inferior to reported outcomes in NETTER-1 probably because of differences in treatment timing and patient populations. Possible variables associated with difference in outcome include pattern of metastatic disease and tumor grade.

Connecting the Human Microbiome and Pancreatic Cancer

Pancreatic cancer is a deadly disease that is increasing in incidence throughout the world. There are no clear causal factors associated with the incidence of pancreatic cancer; however, some correlation to smoking, diabetes and alcohol has been described. Recently, a few studies have linked the human microbiome (oral and gastrointestinal tract) to pancreatic cancer development. A perturbed microbiome has been shown to alter normal cells while promoting cancer-related processes such as increased cell signaling, immune system evasion and invasion. In this article, we will review in detail the alterations within the gut and oral microbiome that have been linked to pancreatic cancer and explore the ability of other microbiomes, such as the lung and skin microbiome, to contribute to disease development. Understanding ways to identify a perturbed microbiome can result in advancements in pancreatic cancer research and allow for prevention, earlier detection and alternative treatment strategies for patients.

Association of PAK4 expression with overall survival in patients with non-small cell lung cancer (NSCLC)

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Background: P21-activated kinase 4 (PAK4) is a crucial effector of the Rho GTPases. It acts as a regulatory switch that controls a wide range of cellular functions and plays a pivotal role in cancer progression and metastasis. Very little is known about the expression and prognostic value of PAK4 in NSCLC. Methods: 17,689 NSCLC tumor samples were analyzed using next-generation sequencing (NextSeq, 592 Genes, or WES NovaSeq), immunohistochemistry (IHC), and whole transcriptome sequencing (NovaSeq) (Caris Life Sciences, Phoenix, AZ). PD-L1 expression was analyzed by IHC (Dako 22c3; PD-L1 positive: TPS >1%). TMB was measured by counting all somatic mutations found per tumor (TMB-high: >10 mutations/MB). Tumors with PAK4-high (H) and PAK4-low (L) expression were classified as those in top quartile and bottom 3 quartiles, respectively. Immune cell infiltrates were calculated by Quantiseq. Significance was determined using chi-square and Wilcoxon rank sum test and adjusted for multiple comparisons (q-value < 0.05). Survival was extracted from insurance claims data and calculated from the time of tissue collection to the last contact using Kaplan-Meier estimates. Results: There was no difference in median age, gender, smoking status, and histologic distribution between PAK-H and PAK-L tumors. Compared to PAK4-L, the PAK4-H was associated with higher frequency of co-mutations in TP53 (76.3% vs 63.9%, p < 0.0001) and RB1 (13.6% vs 8.1%, p < 0.0001). PAK4-H tumors were associated with greater genomic loss of heterozygosity (24.1% vs 16.4%, p < 0.0001), and expression of immune checkpoint genes ( LAG3, PDCD1, PDCD1LG2, CD274, IDO1, CTLA4, CD80, HAVCR2; p < 0.05). KRAS (including KRAS G12C) , BRAF, STK11, and EGFR mutations, and ALK and ROS1 fusions were less frequent in PAK4-H tumors (p < 0.001). A greater proportion of PAK4-H tumors were TMB-H (40.3% vs 33.3%, p < 0.0001) and PD-L1 negative (48.2% vs 40.8%, p < 0.001). PAK4-H tumors had lower infiltration of B cells, M1/M2 macrophages, CD8+ T-cells, and Tregs (p < 0.001). Overall survival (OS) was inferior among patients with PAK4-H tumors (median, 14.9 vs 21.5 months, HR = 1.28, 95% CI, 1.21-1.36, p < 0.001), which was driven by adenocarcinoma histology. Survival with immunotherapy was also inferior in patients with PAK4-H adenocarcinoma (median, 23.6 vs 30.3 months, HR = 1.23, 95% CI, 1.02-1.48, p = 0.03), but not squamous cell carcinoma. A similar trend in survival was noted in patients who received EGFR- and ALK inhibitors. Conclusions: PAK4-H expression in NSCLC is associated with a higher frequency of alterations predisposing to genomic instability, differentially modulated immune phenotype, and a lower frequency of actionable genomic alterations. Patients with PAK4-H adenocarcinoma have inferior OS, and survival with immunotherapy and targeted therapy. PAK4-H expression defines a subgroup of patients with un unmet need for novel treatment strategies.

Inhibitor of the Nuclear Transport Protein XPO1 Enhances the Anticancer Efficacy of KRAS G12C Inhibitors in Preclinical Models of KRAS G12C-Mutant Cancers

The identification of molecules that can bind covalently to KRAS G12C and lock it in an inactive GDP-bound conformation has opened the door to targeting KRAS G12C selectively. These agents have shown promise in preclinical tumor models and clinical trials. FDA has recently granted approval to sotorasib for KRAS G12C mutated non-small cell lung cancer (NSCLC). However, patients receiving these agents as monotherapy generally develop drug resistance over time. This necessitates the development of multi-targeted approaches that can potentially sensitize tumors to KRAS inhibitors. We generated KRAS G12C inhibitor-resistant cell lines and observed that they exhibit sensitivity toward selinexor, a selective inhibitor of nuclear export protein exportin1 (XPO1), as a single agent. KRAS G12C inhibitors in combination with selinexor suppressed the proliferation of KRAS G12C mutant cancer cell lines in a synergistic manner. Moreover, combined treatment of selinexor with KRAS G12C inhibitors resulted in enhanced spheroid disintegration, reduction in the number and size of colonies formed by G12C mutant cancer cells. Mechanistically, the combination of selinexor with KRAS G12C inhibitors suppressed cell growth signaling and downregulated the expression of cell cycle markers, KRAS and NF-kB as well as increased nuclear accumulation of tumor suppressor protein Rb. In an in vivo KRAS G12C cell-derived xenograft model, oral administration of a combination of selinexor and sotorasib was demonstrated to reduce tumor burden and enhance survival. In conclusion, we have shown that the nuclear transport protein XPO1 inhibitor can enhance the anticancer activity of KRAS G12C inhibitors in preclinical cancer models.

Significance

In this study, combining nuclear transport inhibitor selinexor with KRAS G12C inhibitors has resulted in potent antitumor effects in preclinical cancer models. This can be an effective combination therapy for cancer patients that do not respond or develop resistance to KRAS G12C inhibitor treatment.

Selective inhibition of nuclear export: a promising approach in the shifting treatment paradigms for hematological neoplasms

Novel targeted therapeutics alone or in rational combinations are likely to dominate the future management of various hematological neoplasms. However, the challenges currently faced are the molecular heterogeneity in driver lesions and genetic plasticity leading to multiple resistance pathways. Thus, progress has overall been gradual. For example, despite the advent of targeted agents against actionable drivers like FLT3 in acute myeloid leukemia (AML), the prognosis remains suboptimal in newly diagnosed and dismal in the relapsed/refractory (R/R) setting, due to other molecular abnormalities contributing to inherent and acquired treatment resistance. Nuclear export inhibitors are of keen interest because they can inhibit several active tumorigenic processes simultaneously and also synergize with other targeted drugs and chemotherapy. XPO1 (or CRM1, chromosome maintenance region 1) is one of the most studied exportins involved in transporting critical cargoes, including tumor suppressor proteins like p27, p53, and RB1. Apart from the TSP cargo transport and its role in drug resistance, XPO1 inhibition results in retention of master transcription factors essential for cell differentiation, cell survival, and autophagy, rendering cells more susceptible to the effects of other antineoplastic agents, including targeted therapies. This review will dissect the role of XPO1 inhibition in hematological neoplasms, focusing on mechanistic insights gleaned mainly from work with SINE compounds. Future potential combinatorial strategies will be discussed.

Circular RNAs in acute myeloid leukemia

Although mechanistic studies clarifying the molecular underpinnings of AML have facilitated the development of several novel targeted therapeutics, most AML patients still relapse. Thus, overcoming the inherent and acquired resistance to current therapies remains an unsolved clinical problem. While current diagnostic modalities are primarily defined by gross morphology, cytogenetics, and to an extent, by deep targeted gene sequencing, there is an ongoing demand to identify newer diagnostic, therapeutic and prognostic biomarkers for AML. Recent interest in exploring the role of circular RNA (circRNA) in elucidating AML biology and therapy resistance has been promising. This review discerns the circular RNAs’ evolving role on the same scientific premise and attempts to identify its potential in managing AML.

Abstract PO-024: Targeting cellular metabolism with CPI-613 sensitizes pancreatic cancer cells to radiotherapy

Novel treatment strategies for pancreatic ductal adenocarcinoma (PDAC) are desperately needed. Local tumor progression is a cause of significant morbidity and mortality in patients with surgically unresectable disease. Often, regional anatomic structures limit the total doses of radiation therapy (RT) that can be safely delivered. Conventional doses of concurrent chemotherapy and RT (chemo-RT) have shown suboptimal results in local control of disease, progression free survival, and overall survival. Therefore, novel and effective approaches to enhance the efficacy of RT are urgently needed to improve overall survival in unresectable PDAC. Metabolic reprogramming enables cancer cells to adjust their metabolism to support increased energy requirements associated with continuous growth and proliferation. Indeed, metabolic reprogramming is a hallmark of PDAC and is associated with increased tumor cell plasticity and chemo-RT resistance. Cancer-cell mitochondria are key regulators of deranged tumor metabolism and have been shown to guide molecular pathways involved in radio-resistance. There is also expanding data that the presence of metabolites modulates the response of cancer cells to RT primarily by impacting the ability to repair DNA. This makes them an optimal candidate for novel radiosensitization strategies, as these characteristics are unique to PDAC cells, and are limited in normal cells. CPI-613, is an analog of lipoic acid which inhibits pyruvate dehydrogenase (PDH) and α-ketoglutarate dehydrogenase (α-KGDH), thereby disrupting mitochondrial metabolism leading to selective tumor cell killing. The drug has demonstrated significant clinical activity in patients with metastatic PDAC in combination with standard of care chemotherapies. It remains unknown as to the efficacy in patients treated with concurrent chemo-RT. Here we show that combined treatment of RT (2 and 10 Gy) with CPI-613 (used at 200 and 300 μM) causes superior inhibition of pancreatic cancer cell growth (MTT assay and colony formation assay). In addition, we demonstrate enhanced apoptosis (Annexin V FITC and 7AAD assay) of PDAC cells when treated with a combination of RT and CPI-613. Molecular analysis revealed superior inhibition of PDH and α-KGDH at the protein level. Targeted metabolomic analysis on PDAC cells post CPI-613-RT treatment revealed alterations in key mitochondrial metabolites, leading to these findings. These results indicate broader target engagement by this combination treatment, indicating the sensitization of CPI-613 treated PDAC cells to radiotherapy at doses as low as 2 Gy. Furthermore, in our preclinical cellular models, a combination treatment of CPI-613 with either Gemcitabine or 5-FU has shown synergistic effects on the proliferation of PDAC cells. Pre-clinical anti-tumor efficacy of the CPI-613-RT and CPI-613-RT-chemo using subcutaneous and orthotopic PDAC models is planned. Our results bring forward a novel combination of CPI-613-RT that warrants further pre-clinical and early phase clinical investigations.

Citation Format: William A. Hall, Husain Y. Khan, Mandana Kamgar, Susan Tsai, Kathleen Christians, Douglas B. Evans, Philip Philip, Callisia Clarke, Ben George, Beth Erickson, Asfar S. Azmi. Targeting cellular metabolism with CPI-613 sensitizes pancreatic cancer cells to radiotherapy [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2021 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2021;81(22 Suppl):Abstract nr PO-024.

KRAS Inhibitors- yes but what next? Direct targeting of KRAS- vaccines, adoptive T cell therapy and beyond

Kirsten rat sarcoma viral oncogene homolog (KRAS) is a proto-oncogene of the RAS-MAPK pathway. KRAS mutations are present in a variety of malignancies including lung, colorectal, and pancreatic cancer. Until the recent approval of sotorasib, a KRAS G12C inhibitor, lack of targeted therapy for KRAS has resulted in poor prognosis of patients with tumors harboring KRAS mutations. While the conditional approval of sotorasib was a major breakthrough for those patients harboring KRAS G12C mutations, G12C only accounts for a fraction of those with KRAS mutations and eventual resistance to G12C inhibitors are unavoidable. This comprehensive review on KRAS inhibitors covers accumulating evidence on not only the G12C inhibitors but also other therapeutic attempts to tackle KRAS including combination therapy as well as direct inhibition with vaccines, adoptive T cell therapy, proteolysis-targeted chimeras (PROTACs) and CRISPR/Cas9.

Impact of XPO1 mutations on survival outcomes in metastatic non-small cell lung cancer (NSCLC)

BACKGROUND

Nuclear protein transport is essential in guiding the traffic of important proteins and RNAs between the nucleus and cytoplasm. Export of proteins from the nucleus is mostly regulated by Exportin 1 (XPO1). In cancer, XPO1 is almost universally hyperactive and can promote the export of important tumor suppressors to the cytoplasm. Currently, there are no studies evaluating XPO1 amplifications and mutations in NSCLC and the impact on outcomes.

METHODS

Tumor samples were analyzed using next-generation sequencing (NGS) (NextSeq, 592 Genes), immunohistochemistry (IHC), and whole transcriptome sequencing (WTS, NovaSeq) (Caris Life Sciences, Phoenix, AZ). Survival was extracted from insurance claims data and calculated from time of tissue collection to last contact using Kaplan-Meier estimate.

RESULTS

Among 18,218 NSCLC tumors sequenced, 26 harbored XPO1 mutations and 24 had amplifications. XPO1 mutant tumors were more likely to have high TMB (79% vs. 52%, p = 0.007) and less likely to have high PD-L1 (32% vs. 68%, p = 0.03). KRAS co-mutations were seen in 19% (n = 5) and EGFR co-mutations were rare (n = 2). Among the 17,449 NSCLC tumors with clinical data, there were 24 XPO1 mutant. Comparison of survival between XPO1 mutant and WT showed a negative association with a hazard ratio (HR) of 1.932 (95% CI: 1.144-3.264 p = 0.012). XPO1 amplification was not associated with survival.

CONCLUSIONS

XPO1 pathogenic mutations were associated with a poor survival in NSCLC. Although XPO1 mutations are rare in NSCLC, further studies to assess its associations with treatment responses are warranted.

Targeting KRAS in pancreatic cancer: new drugs on the horizon

Kirsten Rat Sarcoma (KRAS) is a master oncogene involved in cellular proliferation and survival and is the most commonly mutated oncogene in all cancers. Activating KRAS mutations are present in over 90% of pancreatic ductal adenocarcinoma (PDAC) cases and are implicated in tumor initiation and progression. Although KRAS is a critical oncogene, and therefore an important therapeutic target, its therapeutic inhibition has been very challenging, and only recently specific mutant KRAS inhibitors have been discovered. In this review, we discuss the activation of KRAS signaling and the role of mutant KRAS in PDAC development. KRAS has long been considered undruggable, and many drug discovery efforts which focused on indirect targeting have been unsuccessful. We discuss the various efforts for therapeutic targeting of KRAS. Further, we explore the reasons behind these obstacles, novel successful approaches to target mutant KRAS including G12C mutation as well as the mechanisms of resistance.

PAK4-NAMPT Dual Inhibition Sensitizes Pancreatic Neuroendocrine Tumors to Everolimus

Metastatic pancreatic neuroendocrine tumors (PNET) remain an unmet clinical problem. Chronologic treatment in PNETs includes observation (watchful protocol), surgery, targeted therapy, and chemotherapy. However, increasing evidence illustrates that the outcomes of targeted therapeutic options for the treatment of advanced PNETs show minimal response. The FDA-approved mTOR inhibitor everolimus does not shrink these tumors. It only delays disease progression in a subset of patients, while a significant fraction acquires resistance and shows disease progression. Thus, there is a need for more effective targeted approaches to sensitize PNETs to everolimus for better treatment outcomes. Previously, we showed that mTOR regulator p21 activated kinase 4 (PAK4) and nicotinamide adenine dinucleotide biosynthesis enzyme nicotinamide phosphoribosyl transferase (NAMPT) were aberrantly expressed in PNET tissue and promoted everolimus resistance. In this report, we demonstrate that PAK4-NAMPT dual inhibitor KPT-9274 can synergize with everolimus (growth inhibition, colony suppression, and glucose uptake assays). KPT-9274-everolimus disrupted spheroid formation in multiple PNET models. Molecular analysis showed alteration of mTORC2 through downregulation of RICTOR as a mechanism supporting synergy with everolimus in vitro KPT-9274 suppressed β-catenin activity via inhibition of PAK4, highlighting the cross-talk between Rho GTPases and Wnt signaling in PNETs. KPT-9274, given at 150 mg/kg in combination with sub-MTD everolimus (2.5 mg/kg), significantly suppressed two PNET-derived xenografts. These studies bring forward a well-grounded strategy for advanced PNETs that fail to respond to single-agent everolimus.

Abstract 2383: Mir-7974: An oncogenic miRNA that perpetuates gastric cancer

The global incidence of gastric cancer exceeds 1 million people per year and has a 5-year survival rate of 31%. Current chemotherapies are not effective because of genetic and epigenetic heterogeneity and late stage detection. Previously, we showed that exportin 1 (XPO1) is a therapeutic target in gastric cancer, as it facilitates the nuclear export of various cancer related tumor suppressor proteins (TSPs) through direct interaction with their nuclear export sequences (NES). XPO1 is upregulated in a variety of tumors including gastric cancer, leading to increased cytoplasmic localization of TSPs supporting malignant transformation and cancer cell proliferation, Knockdown of XPO1 leads to anti-tumor effects and pharmacologic targeting of XPO1 is achievable with selective inhibitors of nuclear export (SINE) compounds. In 2019 and 2020, the first generation XPO1 inhibitor KPT-330 was FDA approved for the use in penta-refractory multiple myeloma and non-Hodgkin's Lymphoma. Besides protein, mRNA and non-coding RNAs are also transported across the nuclear membrane. Non-coding RNA transport is generally attributed to another nuclear export protein, exportin 5 (XPO5), which plays a critical role in microRNA (miRNA) biogenesis. Nevertheless, there is emerging evidence supporting the role of XPO1 in non-coding RNA transport. In order to elucidate the role of XPO1 in non-coding RNA biology, we performed small RNA sequencing on gastric cancer cell lines treated with the XPO1 inhibitor selinexor. Our results revealed statistically significant changes in miR-7974 and miR-129-1-3p. These two miRs are recognized to influence protein modifications and cell survival. Administration of a miR-7974 mimic and a miR-129-1-3p inhibitor reduced proliferation of gastric cancer cells. Next, we evaluated the miR target genes of interest. At the mRNA level, we found upregulation of RasGEF Domain Family Member 1a (RASGEF1A), downregulation of DNA damage-regulated autophagy modulator 1 (DRAM1), downregulation of TIMP2 and downregulation of Cyclin G2 protein encoding gene CCNG2. Western Blots confirmed inhibition of AKT, RAS and Wnt signaling. Our results also showed that miR-7974 overexpression correlated with cellular XPO1 levels through the enhancement of XPO1 and its cargoes RCC1 and RANBP2. Finally inhibition of XPO1 by SINE compounds reversed the observed oncogenic phenotypes caused by these microRNAs. Our results unveil a novel interaction network between XPO1 and small non-coding RNAs and show that XPO1 induced small-noncoding microRNAs influence gastric cancer proliferation, and can be reversed by SINE compounds. This implies that modulation of microRNAs might be explored as a biomarker for XPO1 inhibitor therapy and warrants further investigation.

Citation Format: Rachel E. Sexton, Mohammad Najeeb Al-Hallak, Bayan Al-Share, Yiwei Li, Amro Aboukameel, Yosef Landesman, Trinayan Kashyap, Steve Kim, Ramzi M. Mohammad, Philip A. Philip, Asfar S. Azmi. Mir-7974: An oncogenic miRNA that perpetuates gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2383.

Abstract 1122: Novel targets for therapy resistant pancreatic neuroendocrine tumors

Pancreatic Neuroendocrine Tumors (PNETs) remains an unmet clinical problem and epidemiologic studies indicate that their incidence has significantly increased over the years. Surgery remains the only curative option in patients with localized tumors. However, there is no effective therapy in patients with advanced or metastatic disease. Thus, unfortunately, 65% of PNET patients with advanced/unresectable disease die within 5 years after diagnosis. Current therapeutic approaches for advanced PNET patients include chemotherapy (Capecitabine, Temolozomide, 5FU etc), targeted therapies (everolimus, and sunitinib), hormonal therapies [somatostatin analogs (octreotide or lanreotide)] and the novel peptide receptor radionuclide therapy. Nevertheless, all these therapeutic modalities show only minimal response in patients with PNETs in the clinic. Therefore, novel targets need to be identified that could improve the dismal outcome of advanced PNETs. An analysis of PNET tissue identified p21-activated Kinase 4 (PAK4) and nicotinamide Phosphoribosyltransferase (NAMPT) as two new therapeutic targets. PAK4 is the downstream effector of Rac1 (members of the Rho family of GTPases) and is involved in critical cellular processes such as cell motility, proliferation, and survival. More importantly, PAK4 protein has been implicated in the activation of Ras/Raf/Mek/Erk and PI3K/Akt/mTOR signaling in cancers. Similarly, NAMPT is an enzyme that catalyzes the rate-limiting step in the principal salvage pathway of NAD biosynthesis in mammals. Tumor cells have highly active glycolytic, pentose and fatty acid synthesis pathways that require persistent high levels of NAD. Consequently, most cancers rely more heavily on NAMPT for rapid NAD biosynthesis. Earlier we demonstrated that biological or chemical inhibition of PAK4-NAMPT by RNAi or by a dual inhibitor (KPT-9274 a Phase I drug and its analogs) can suppress PNET proliferation and reduce the growth of subcutaneous xenografts. Our new studies show that PAK4-NAMPT dual inhibition can suppress PNET anchorage independent growth and metabolomic analysis of KPT-9274 treated PNET cells revealed significant alterations in a series of metabolites related to NAD signaling. KPT-9274 synergistically enhanced the anti-tumor activity of everolimus (combination index &lt;1). Molecular analysis of combination treatment showed down-regulation of known everolimus resistance drivers including mTORC1, mTORC2, PI3K, ERK, FAK, RICTOR, ß-catenin. Importantly, combination treatment of KPT-9274 (150mg/kg) and everolimus (2.5 mg/kg used at sub-optimal dose) caused reduction of PNET xenografts. Our investigations demonstrate that PAK4 and NAMPT are two viable therapeutic targets in the difficult to treat PNETs that warrant further clinical investigations.

Citation Format: Gabriel B. Mpilla, Amro Aboukameel, Md Hafiz Uddin, Mohammed N. Al-Hallak, Bayan Al-Share, Yosef Landesman, Yiwei Li, Steve Kim, Rafic Beydoun, Ramzi M. Mohammad, Philip A. Philip, Bassel El-Rayes, Asfar S. Azmi. Novel targets for therapy resistant pancreatic neuroendocrine tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1122.

Abstract 1058: Inhibition of nuclear transport protein XPO1 potentiates the effect of KRASG12C inhibitors

Introduction: The discovery of compounds that can bind covalently to KRASG12C and lock it in its inactive GDP-bound conformation has opened a window of opportunity to selectively target KRASG12C. Such agents have shown promising results in preclinical tumor models and recently in clinical trials as well. However, factors such as feedback reactivation or bypass of KRAS dependence are known to limit antitumor activity of KRAS inhibitors. This necessitates the need for combination approaches that can potentially sensitize tumors to KRAS inhibitors when co-targeted. In this study, we have tested two potent KRASG12C inhibitors, MRTX1257 and AMG510, on PDAC and NSCLC cell lines both as single agents and also in combination with nuclear transport inhibitor, Selinexor (KPT-330/XPOVIO).

Methods: Cell growth inhibition was determined by MTT assay. Drug synergy analysis was performed and the isobolograms were generated using CalcuSyn 2.1 software (Biosoft, Cambridge, UK). Spheroid disintegration assay, clonogenic assay, immunofluorescence assay, and Western blotting were performed by standard methods.

Results: MRTX1257 and AMG510, when combined with KPT-330, synergistically inhibited (Combination Index values less than 1) the proliferation of KRASG12C mutant cancer cell lines, namely MiaPaCa-2 (PDAC) and NCI-H2122 (NSCLC). Such an effect was observed neither in KRASWT (NCI-H1650) nor KRASG12D mutant (Panc-1) cells, suggesting that the synergistic effect on cell viability was specific to KRASG12C. Combined treatment of KPT-330 with either MRTX1257 or AMG510 resulted in enhanced disintegration of MiaPaCa-2 and NCI-H2122 spheroids, indicating the efficacy of the drug combinations in a 3-D cell growth model. In addition, similar synergistic action was also seen in a clonogenic assay, where MRTX1257 and AMG510 reduced the number and size of colonies formed by MiaPaCa-2 cells and KPT-330 further augmented this effect. KPT-330 also potentiated the MRTX1257- or AMG510-induced inhibition of KRAS-dependent signaling targets such as ERK1/2 phosphorylation. Mechanistically, we observed that KPT-330 caused nuclear retention of ETS repressor factor (ERF), a transcriptional repressor that is exported upon phosphorylation by ERK. Given that XPO1 transports hundreds of proteins, we are currently evaluating the global changes in RAS pathway proteins using high throughput approaches. Such studies are anticipated to unveil the molecular underpinnings of the effectiveness of this co-targeting approach that would help advance this combination of nuclear transport inhibitor with KRASG12C inhibitors to be tested in the clinic.

Conclusion: In conclusion, we have demonstrated that the inhibitor of nuclear transport protein XPO1 has the ability to potentiate the anticancer activity of KRASG12C inhibitors in in vitro preclinical models of PDAC and NSCLC.

Citation Format: Husain Y. Khan, Md. Hafiz Uddin, Yue Zhang, Yosef Landesman, Ammar Sukari, Misako Nagasaka, Asfar S. Azmi. Inhibition of nuclear transport protein XPO1 potentiates the effect of KRASG12C inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1058.

Liquid biopsy for therapy monitoring in early-stage non-small cell lung cancer

Liquid biopsy is now considered a valuable diagnostic tool for advanced metastatic non-small cell lung cancer (NSCLC). In NSCLC, circulating tumor DNA (ctDNA) analysis has been shown to increase the chances of identifying the presence of targetable mutations and has been adopted by many clinicians owing to its low risk. Serial monitoring of ctDNA may also help assess the treatment response or for monitoring relapse. As the presence of detectable plasma ctDNA post-surgery likely indicates residual tumor burden, studies have been performed to quantify plasma ctDNA to assess minimal residual disease (MRD) in early-stage resected NSCLC. Most data on utilizing liquid biopsy for monitoring MRD in early-stage NSCLC are from small-scale studies using ctDNA. Here, we review the recent research on liquid biopsy in NSCLC, not limited to ctDNA, and focus on novel methods such as micro RNAs (miRNA) and long non-coding (lncRNA).

Prognostic impact of XPO1 mutations in metastatic non-small cell lung cancer (NSCLC)

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Background: Nuclear protein transport is essential in guiding the organized traffic of important proteins and RNAs between the nucleus and cytoplasm of the cell. Export of proteins from the nucleus is exclusively regulated by Exportin 1(XPO1). In cancer, XPO1 is universally hyperactive and can promote the export of important tumor suppressors to the cytoplasm, leading to their functional inactivation. XPO1 is aberrantly over expressed in NSCLC and this over expression has been linked to poor overall survival. The underlying mechanisms of XPO1 over expression are not known. Currently there are no studies evaluating the impact of XPO1 mutations on NSCLC incidence and therapy resistance. Additionally, there are no studies that examined the XPO1 related pathways in NSCLC harboring co-alterations with other driver mutations such as EGFR or ALK. Methods: Tumor samples were analyzed using next-generation sequencing (NextSeq, 592 Genes), IHC, and whole transcriptome sequencing (WTS ,NovaSeq) (Caris Life Sciences, Phoenix, AZ). PD-L1 expression was tested by IHC using 22c3 (Dako) and TPS scores were reported (cutoff > 1%). TMB was measured by totaling somatic mutations (TMB-high cut-off ³ 10 mutations per Megabase). Gene fusions were detected by RNA sequencing using either the Archer FusionPlex panel or WTS. Survival was extracted from insurance claims data and calculated from time of tissue collection to last contact using Kaplan-Meier estimate. Statistical significance was determined using chi-square and Wilcoxon rank sum test and adjusted for multiple comparisons. Results: Among 18,218 NSCLC tumors sequenced, 26 harbored XPO1 mutations. XPO1 mutant tumors were more likely to be TMB High(79% vs. 52%, p = 0.007) and less likely to have high PDL1(32% vs. 68%, p = 0.03). KRAS mutations were seen in 19%(n = 5), EGFR mutation were rare (n = 2), and no targetable fusions were seen. Among the 17,449 NSCLC tumors with clinical data, there were 24 XPO1 mutant tumors with no histology imbalance observed in mutant vs. wild-type(WT). Comparison of survival in the NSCLC group between XPO1 mutant and WT showed a negative association with a hazard ratio(HR) of 1.932 (95% CI: 1.144- 3.264 p = 0.012). Comparing the survival within the subgroup with confirmed adenocarcinoma histology (9973 XPO1 WT and 14 XPO1 mutant) showed a similar negative correlation in survival with a HR of 2.156 (95% CI: 1.027- 4.525 P = 0.037). Conclusions: Presence of XPO1 pathogenic mutations was associated with a poor survival in both the entire NSCLC cohort and the adenocarcinoma subgroup. Further studies of this negative association at the molecular level along with effect of other co-existing mutations can result in development of novel treatment strategies.

microRNA-based diagnostic and therapeutic applications in cancer medicine

It has been almost two decades since the first link between microRNAs and cancer was established. In the ensuing years, this abundant class of short noncoding regulatory RNAs has been studied in virtually all cancer types. This tremendously large body of research has generated innovative technological advances for detection of microRNAs in tissue and bodily fluids, identified the diagnostic, prognostic, and/or predictive value of individual microRNAs or microRNA signatures as potential biomarkers for patient management, shed light on regulatory mechanisms of RNA-RNA interactions that modulate gene expression, uncovered cell-autonomous and cell-to-cell communication roles of specific microRNAs, and developed a battery of viral and nonviral delivery approaches for therapeutic intervention. Despite these intense and prolific research efforts in preclinical and clinical settings, there are a limited number of microRNA-based applications that have been incorporated into clinical practice. We review recent literature and ongoing clinical trials that highlight most promising approaches and standing challenges to translate these findings into viable microRNA-based clinical tools for cancer medicine. This article is categorized under: RNA in Disease and Development > RNA in Disease.

Selinexor in Combination with R-CHOP for Frontline Treatment of Non-Hodgkin Lymphoma: Results of a Phase I Study

PURPOSE

The nuclear exporter protein exportin-1 (XPO1) is overexpressed in non-Hodgkin lymphoma (NHL) and correlates with poor prognosis. We evaluated enhancing R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) activity in NHL by targeted inhibition of XPO1 using the selective inhibitor of nuclear export (SINE) compounds.

PATIENTS AND METHODS

We evaluated the antitumor activity of SINE compounds in combination with CHO chemotherapy in vitro and in vivo. Newly diagnosed NHL patients in a phase I dose-escalation study received R-CHOP for 6 cycles with weekly selinexor (60, 80, and 100 mg), then selinexor maintenance therapy for one year. RT-PCR, Western blotting, and RNA sequencing were performed on patient blood samples.

RESULTS

SINE compounds synergized with CHO in vitro in NHL cell lines and in vivo in our murine xenograft model. In our phase I study, selinexor was dosed at 60 mg (n = 6) and 80 mg (n = 6). The most common adverse events (AE) among 12 patients were fatigue (67%) and nausea (100%). Grade 3-4 AEs were infrequent. Ten evaluable patients had an overall response rate of 100% and complete remission rate of 90% with sustained remissions (median follow-up: 476 days). Maximally tolerated dose was not reached; however, the recommended phase II dose was 60 mg selinexor weekly after evaluating tolerability and discontinuation rates for each dose cohort. Analysis of patient blood samples revealed downregulation of XPO1 and several prosurvival markers.

CONCLUSIONS

SINE compounds enhance the activity of CHO in vitro and in vivo. Selinexor in combination with R-CHOP was generally well tolerated and showed encouraging efficacy in NHL (NCT03147885).

The nuclear export protein XPO1 - from biology to targeted therapy

Exportin 1 (XPO1), also known as chromosome region maintenance protein 1, plays a crucial role in maintaining cellular homeostasis via the regulated export of a range of cargoes, including proteins and several classes of RNAs, from the nucleus to the cytoplasm. Dysregulation of this protein plays a pivotal role in the development of various solid and haematological malignancies. Furthermore, XPO1 is associated with resistance to several standard-of-care therapies, including chemotherapies and targeted therapies, making it an attractive target of novel cancer therapies. Over the years, a number of selective inhibitors of nuclear export have been developed. However, only selinexor has been clinically validated. The novel mechanism of action of XPO1 inhibitors implies a different toxicity profile to that of other agents and has proved challenging in certain settings. Nonetheless, data from clinical trials have led to the approval of the XPO1 inhibitor selinexor (plus dexamethasone) as a fifth-line therapy for patients with multiple myeloma and as a monotherapy for patients with relapsed and/or refractory diffuse large B cell lymphoma. In this Review, we summarize the progress and challenges in the development of nuclear export inhibitors and discuss the potential of emerging combination therapies and biomarkers of response.

Gastric cancer: a comprehensive review of current and future treatment strategies

Gastric cancer remains a major unmet clinical problem with over 1 million new cases worldwide. It is the fourth most commonly occurring cancer in men and the seventh most commonly occurring cancer in women. A major fraction of gastric cancer has been linked to variety of pathogenic infections including but not limited to Helicobacter pylori (H. pylori) or Epstein Barr virus (EBV). Strategies are being pursued to prevent gastric cancer development such as H. pylori eradication, which has helped to prevent significant proportion of gastric cancer. Today, treatments have helped to manage this disease and the 5-year survival for stage IA and IB tumors treated with surgery are between 60 and 80%. However, patients with stage III tumors undergoing surgery have a dismal 5-year survival rate between 18 and 50% depending on the dataset. These figures indicate the need for more effective molecularly driven treatment strategies. This review discusses the molecular profile of gastric tumors, the success, and challenges with available therapeutic targets along with newer biomarkers and emerging targets.

Association of ALDH1A1-NEK-2 axis in cisplatin resistance in ovarian cancer cells

Development of acquired resistance to cisplatin (CDDP) is a major obstacle in the treatment of ovarian cancer patients. According to the cancer stem cell (CSC) hypothesis, the recurrence and chemoresistance are presumed to be linked to cancer stem/progenitor cells. Here, we investigated the CSC-like phenotypes and mechanism of chemoresistance in CDDP resistant ovarian cancer cells. A well-established CDDP sensitive ovarian cancer cell line A2780 and its resistant population A2780-Cp were used. We also developed a supra resistant population (SKOV3-Cp) from a naturally CDDP resistant cell line SKOV3. Both resistant/supra resistant cell lines showed significantly higher self-renewal capability than their parental counterparts. They also showed significant resistance to apoptosis and sub-G1 arrest by CDDP treatment. Stem cell marker ALDH1 positivity rates were higher both in A2780-Cp and SKOV3-Cp cell lines than in their counterparts, quantified by Aldefluor assay kit. Hoechst 33342 dye effluxing side populations were increased up to about five folds in A2780-Cp cells and two folds in SKOV3-Cp cells compared to A2780 and SKOV3 cells, respectively. Among major stemness related genes (POU5F1/OCT4, SOX2, NANOG, NES, BMI1, KLF4 and ALDH1A1), ALDH1A1 and KLF4 were significantly overexpressed in both resistant/supra resistant cells. Silencing ALDH1A1 in A2780 and A2780-Cp cells using siRNA greatly reduced the stem cell population and sensitized cells to CDDP. Moreover, silencing of ALDH1A1 reduced the transcript and protein level of its downstream target NEK-2. We also observed the downregulation of ABC transporters (ABCB1/MDR1, ABCG2 and ABCC1/MRP1) either by ALDH1A1 or NEK-2 silencing and upreguation of ABCB1/MDR1 due to the overexpression of NEK-2. Taken together, the present study suggests that stemness gene ALDH1A1 can be involved in CDDP resistance through the upregulation of NEK-2 in ovarian cancer.

Exportin 1 inhibition as antiviral therapy

Coronavirus 2019 (COVID-19; caused by Severe Acute Respiratory Syndrome Coronavirus 2; SARS-CoV-2) is a currently global health problem. Previous studies showed that blocking nucleocytoplasmic transport with exportin 1 (XPO1) inhibitors originally developed as anticancer drugs can quarantine key viral accessory proteins and genomic materials in the nucleus of host cell and reduce virus replication and immunopathogenicity. These observations support the concept of the inhibition of nuclear export as an effective strategy against an array of viruses, including influenza A, B, and SARS-CoV. Clinical studies using the XPO1 inhibitor selinexor as a therapy for COVID-19 infection are in progress.

Gastric Cancer Heterogeneity and Clinical Outcomes

Gastric adenocarcinoma is a highly aggressive disease with poor overall survival. The aggressive nature of this disease is in part due to the high intra and inter tumoral heterogeneity and also due to the late diagnosis at presentation. Once progression occurs, treatment is more difficult due to the adaptation of tumors, which acquires resistance to commonly used chemotherapeutics. In this report, using publicly available data sets and pathway analysis, we highlight the vast heterogeneity of gastric cancer by investigating genes found to be significantly perturbed. We found several upregulated genes in the diffuse gastric cancer subtypes share similarity to gastric cancer as a whole which can be explained by the increase in this subtype of gastric cancer throughout the world. We report significant downregulation of genes that are underrepresented within the literature, such as ADH7, GCNT2, and LIF1, while other genes have not been explored within gastric cancer to the best of our knowledge such as METTL7A, MAL, CWD43, and SLC2A12. We identified gender to be another heterogeneous component of this disease and suggested targeted treatment strategies specific to this heterogeneity. In this study, we provide an in-depth exploration of the molecular landscape of gastric cancer in order to shed light onto novel areas of gastric cancer research and explore potential new therapeutic targets.

Abstract 234: A novel, small molecule inhibitor of dihydroorotate dehydrogenase (DHODH), RP7214, potentiates activity of chemotherapeutics in breast and colorectal cancers

Background: Dihydroorotate dehydrogenase (DHODH) is an enzyme which is critically involved in process of de novo pyrimidine biosynthesis. Therefore, it plays important roles in cell proliferation, mitosis and cellular metabolism. Importantly, overexpression of DHODH has been found in various types of malignant tumors including melanoma, myeloma, and lymphoma. Moreover, from Oncomine database, we observed that colorectal and kidney cancers and lymphoma have much higher expression of DHODH compared to normal cells. These findings suggest that DHODH could be a promising target for cancer therapy. Recently, we have designed and synthesized a novel small molecule inhibitor (RP7214) of DHODH and found that it has potent inhibitory effects in acute myeloid leukemia. However, the inhibitory effect of RP7214 on solid tumor-derived cell lines and the downstream oncogenic markers is not completely understood.

Methods: In vitro studies aimed at elucidating the effects of RP7214 on cell proliferation and the underlying molecular mechanisms were conducted using breast adenocarcinoma (MDA-MB-231) and colorectal carcinoma cell lines (HT-29 and HCT-116). We also investigated whether RP7214 could potentiate the anti-cancer activities of proven chemotherapeutics such as Verzenio, Doxorubicin, and Oxaliplatin, for the treatment of breast and colorectal cancers.

Results: RP7214 significantly (P&lt;0.05) inhibited proliferation and suppressed colony formation in MDA-MB-231, HT-29, and HCT-116 cells. Isobologram analysis showed that RP7214 synergistically enhanced the inhibitory effects of Verzenio and Doxorubicin on MDA-MB-231 cells proliferation. RP7214 and Oxaliplatin also showed synergistic inhibitory effects on the growth of HT-29 and HCT-116 colorectal cancer cells. Up-regulation of p21 with concomitant down-regulation of Bcl-2, myc, CDK6, and UAP1 in MDA-MB-231 cells treated with RP7214 alone or in combination with Doxorubicin was observed. Similarly, RP7214 also up-regulated the expression of p21 and Bax, and down-regulated the expression of CDK4, Akt, HOXA9, EZH2, and snail in HT-29 or HCT-116 cells treated with or without Oxaliplatin. These results suggest that the inhibitory effects of RP7214 on cancer cells could be mediated through the regulation of cell cycle, apoptosis, and metabolism pathways.

Conclusions: Based on these results, we conclude that RP7214 could be a promising DHODH inhibitor used in combination with conventional chemotherapeutics for better treatment of breast and colorectal cancers. We are now conducting animal experiment to confirm the value of RP7214 in vivo in combination treatment of breast and colorectal cancers.

Citation Format: Asfar S. Azmi, Amro Aboukameel, Mohammad Najeeb Al-Hallak, Philip A. Philip, Kumar Penmetsa, Srikant Visvanadha, Gabriel Mpilla, Rachel Sexton, Ramzi M. Mohammad. A novel, small molecule inhibitor of dihydroorotate dehydrogenase (DHODH), RP7214, potentiates activity of chemotherapeutics in breast and colorectal cancers [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 234.

Preclinical Assessment with Clinical Validation of Selinexor with Gemcitabine and Nab-Paclitaxel for the Treatment of Pancreatic Ductal Adenocarcinoma

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) remains a deadly disease urgently requiring new treatments. Overexpression of the protein transporter exportin-1 (XPO1) leads to mislocalization of tumor-suppressor proteins (TSP) and their inactivation. Earlier, we showed that blocking XPO1 by CRISPR/Cas9 validated Selective Inhibitor of Nuclear Export (SINE) compounds (selinexor and analogs) restores the antitumor activity of multiple TSPs leading to suppression of PDAC in vitro and in orthotopic models.

EXPERIMENTAL DESIGN

We evaluate the synergy between SINE compounds and standard-of-care treatments in preclinical models and in a PDAC Phase Ib trial.

RESULTS

SINE compounds synergize with gemcitabine (GEM) and nanoparticle albumin-bound (nab)-paclitaxel leading to suppression of PDAC cellular growth and cancer stem cell (CSC) spheroids disintegration. Label-free quantitative proteome profiling with nuclear and cytoplasmic enrichment showed superior enhancement in nuclear protein fraction in combination treatment. Selinexor inhibited the growth of PDAC CSC and two patient-derived (PDX) subcutaneous xenografts. Selinexor-GEM-nab-paclitaxel blocked PDX and orthotopic tumor growth. In a phase 1b study (NCT02178436), 9 patients were exposed to selinexor (60 mg oral) with GEM (1,000 mg/m2 i.v.) and nab-paclitaxel (125 mg/m2 i.v.) on days 1, 8, and 15 of 28-day cycle. Two patients showed partial response, and 2 had stable disease. An outstanding, durable objective response was observed in one of the responders with progression-free survival of 16 months and overall survival of 22 months.

CONCLUSIONS

Our preclinical and ongoing clinical study lends support to the use of selinexor-GEM-nab-paclitaxel as an effective therapy for metastatic PDAC.

KRAS G12C Game of Thrones, which direct KRAS inhibitor will claim the iron throne?

Mutations in Kirsten rat sarcoma viral oncogene homolog (KRAS) are among the most common aberrations in cancer, including non-small cell lung cancer (NSCLC). The lack of an ideal small molecule binding pocket in the KRAS protein and its high affinity towards the abundance of cellular guanosine triphosphate (GTP) renders the design of specific small molecule drugs challenging. Despite efforts, KRAS remains a challenging therapeutic target. Among the different known mutations; the KRASG12C (glycine 12 to cysteine) mutation has been considered potentially druggable. Several novel covalent direct inhibitors targeting KRASG12C with similar covalent binding mechanisms are now in clinical trials. Both AMG 510 from Amgen and MRTX849 from Mirati Therapeutics covalently binds to KRASG12C at the cysteine at residue 12, keeping KRASG12C in its inactive GDP-bound state and inhibiting KRAS-dependent signaling. Both inhibitors are being studied as a single agent or as combination with other targets. In addition, two novel KRAS G12C inhibitors JNJ-74699157 and LY3499446 will have entered phase 1 studies by the end of 2019. Given the rapid clinical development of 4 direct covalent KRAS G12C inhibitors within a short period of time, understanding the similarities and differences among these will be important to determine the best treatment option based on tumor specific response (NSCLC versus colorectal carcinoma), potential resistance mechanisms (i.e. anticipated acquired mutation at the cysteine 12 residue) and central nervous system (CNS) activity. Additionally, further investigation evaluating the efficacy and safety of combination therapies with agents such as immune checkpoint inhibitors will be important next steps.

Targeting XPO1 and PAK4 in 8505C Anaplastic Thyroid Cancer Cells: Putative Implications for Overcoming Lenvatinib Therapy Resistance

Lenvatinib is a multitargeted tyrosine kinase inhibitor (TKI) that shows improved median progression-free survival (PFS) in patients with thyroid carcinomas. However, virtually all patients ultimately progress, indicating the need for a better understanding of the mechanisms of resistance. Here, we examined the molecular profile of anaplastic thyroid cancer cells (8505C) exposed to lenvatinib and found that long-term exposure to lenvatinib caused phenotypic changes. Consistent with change toward mesenchymal morphology, activation of pro-survival signaling, nuclear exporter protein exportin 1 (XPO1) and Rho GTPase effector p21 activated kinases (PAK) was also observed. RNA-seq analysis showed that prolonged lenvatinib treatment caused alterations in numerous cellular pathways and several oncogenes such as CEACAM (carcinoembryonic antigen-related cell adhesion molecule) and NUPR1 (Nuclear protein 1) were also upregulated. Further, we evaluated the impact of XPO1 and PAK4 inhibition in the presence or absence of lenvatinib. Targeted inhibition of XPO1 and PAK4 could sensitize the 8505C cells to lenvatinib. Both XPO1 and PAK4 inhibitors, when combined with lenvatinib, showed superior anti-tumor activity in 8505C sub-cutaneous xenograft. These studies bring forward novel drug combinations to complement lenvatinib for treating anaplastic thyroid cancer. Such combinations may possibly reduce the chances of lenvatinib resistance in thyroid cancer patients.

Gut microbiome and response to checkpoint inhibitors in non-small cell lung cancer-A review

The gut microbiome is a collection of diverse bacteria that normally reside within the gastrointestinal tract. In recent years, the relationship between the gut microbiome, and fluctuations in it, and overall health has been an intense area of interest in medical research. In addition to having a barrier role in the gastrointestinal tract, there appears to be an immune function of gut microbiota, with a correlation between dysbiosis of gut microbiota and certain inflammatory and malignant disease states of the gastrointestinal system. We have also seen evidence that the gut microbiome can impact response to immunotherapy in melanoma patients. Evidence has also emerged to show that the lung has a microbiome of its own. In this review we will explore the relationship between the gut and lung microbiomes, known as the gut-lung axis, and the potential effects of this axis on anticancer therapy in lung cancer, including checkpoint inhibitors.

miRNA and Gene Expression in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) remains a challenging disease that is mostly diagnosed late in the course of the illness. Unlike other cancers in which measurable successes have been achieved with traditional chemotherapy, targeted therapy, and, recently, immunotherapy, PDAC has proved to be poorly responsive to these treatments, with only marginal to modest incremental benefits using conventional cytotoxic therapy. There is, therefore, a great unmet need to develop better therapies based on improved understanding of biology and identification of predictive and prognostic biomarkers that would guide therapy. miRNAs are small noncoding RNAs that regulate the expression of some key genes by targeting their 3'-untranslated mRNA region. Aberrant expression of miRNAs has been linked to the development of various malignancies, including PDAC. A series of miRNAs have been identified as potential tools for early diagnosis, prediction of treatment response, and prognosis of patients with PDAC. In this review, we present a summary of the miRNAs that have been studied in PDAC in the context of disease biology.

Targeting Nuclear Exporter Protein XPO1/CRM1 in Gastric Cancer

Gastric cancer remains an unmet clinical problem in urgent need of newer and effective treatments. Here we show that the nuclear export protein, Exportin 1 (XPO1, chromosome region maintenance 1 or CRM1), is a promising molecular target in gastric cancer. We demonstrate significant overexpression of XPO1 in a cohort of histologically diverse gastric cancer patients with primary and metastatic disease. XPO1 RNA interference suppressed gastric cancer cell growth. Anti-tumor activity was observed with specific inhibitor of nuclear export (SINE) compounds (selinexor/XPOVIO), second-generation compound KPT-8602/eltanexor, KPT-185 and +ve control Leptomycin B in three distinct gastric cancer cell lines. SINE compounds inhibited gastric cancer cell proliferation, disrupted spheroid formation, induced apoptosis and halted cell cycle progression at the G1/S phase. Anti-tumor activity was concurrent with nuclear retention of tumor suppressor proteins and inhibition of colony formation. In combination studies, SINE compounds enhanced the efficacy of nab-paclitaxel in vitro and in vivo. More significantly, using non-coding RNA sequencing studies, we demonstrate for the first time that SINE compounds can alter the expression of non-coding RNAs (microRNAs and piwiRNAs). SINE treatment caused statistically significant downregulation of oncogenic miR-33b-3p in two distinct cell lines. These studies demonstrate the therapeutic significance of XPO1 in gastric cancer that warrants further clinical investigation.