XPO1 Expression Research Articles

The nuclear export protein XPO1 provides a peptide ligand for natural killer cells.

XPO1 (Exportin-1/CRM1) is a nuclear export protein that is frequently overexpressed in cancer and functions as a driver of oncogenesis. Currently small molecules that target XPO1 are being used in the clinic as anticancer agents. We identify XPO1 as a target for natural killer (NK) cells. Using immunopeptidomics, we have identified a peptide derived from XPO1 that can be recognized by the activating NK cell receptor KIR2DS2 in the context of human leukocyte antigen-C. The peptide can be endogenously processed and presented to activate NK cells specifically through this receptor. Although high XPO1 expression in cancer is commonly associated with a poor prognosis, we show that the outcome of specific cancers, such as hepatocellular carcinoma, can be substantially improved if there is concomitant evidence of NK cell infiltration. We thus identify XPO1 as a bona fide tumor antigen recognized by NK cells that offers an opportunity for a personalized approach to NK cell therapy for solid tumors.

XPO1 serves as a prognostic marker involving AKT/MAPK/TGFBR1 pathway in OSCC.

Exportin 1 (XPO1) is a nuclear export protein that facilitates the transportation of various substances. XPO1 promotes tumor development as a poor prognostic factor in a variety of tumors and is a therapeutic target for screening inhibitors. However, the role of XPO1 in oral squamous cell carcinoma (OSCC) has yet to be determined. The expression patterns of XPO1 mRNA in OSCC were investigated using bioinformatics tools, and the expression levels of XPO1 protein in OSCC specimens were confirmed by immunohistochemical assays. Survival analysis was conducted to evaluate the impact of XPO1 on prognosis. GO and KEGG enrichment analyses were utilized to uncover the signaling pathways mediated by XPO1. Additionally, we examined the association between XPO1 and AKT/MAPK/TGFBR1 and immune infiltration. XPO1 mRNA and protein expression levels were significantly enhanced in OSCC and associated with OSCC severity. Enhanced XPO1 expression was indicative of poor survival. Functional analysis showed that XPO1 mediated pathways associated with cell cycle and DNA replication and reduced immune infiltration in OSCC. Additionally, XPO1 mRNA and protein expression levels had significant positive relationships with AKT/MAPK/TGFBR1. XPO1, as a marker of poor prognosis in OSCC, can promote OSCC through AKT/MAPK/TGFBR1.

LncRNA HILPDA promotes contrast-induced acute kidney injury by recruiting eIF4B to upregulate XPO1 expression.

Contrast-induced acute kidney injury (CI-AKI) is a serious and common complication following the use of iodinated contrast media, with a 20% fatality rate. The function of long non-coding RNA HILPDA (lnc-HILPDA) in CI-AKI development was investigated in this study. CI-AKI models were constructed by iopromide treatment. Kidney pathological changes were analyzed by HE staining. TUNEL labeling and flow cytometry were used to examine cell apoptosis. CCK-8 assay was used to determine cell viability. The interactions between lnc-HILPDA, eIF4B, and XPO1 were verified by RIP or Co-IP assay. Lnc-HILPDA was upregulated in CI-AKI, and its knockdown decreased contrast-trigged oxidative stress and apoptosis in HK-2 cells. Mechanically, lnc-HILPDA activated the NF-κB pathway by upregulating XPO1 through interacting with eIF4B. Moreover, the inhibitory effect of lnc-HILPDA downregulation on contrast-induced oxidative stress and apoptosis in HK-2 cells was weakened by XPO1 overexpression. Lnc-HILPDA accelerated CI-AKI progression by elevating XPO1 expression through eIF4B to activate NF-κB pathway.

High XPO1 Expression can Stratify Gastric Cancer Patients with Poor Clinical Outcome

High XPO1 Expression can Stratify Gastric Cancer Patients with Poor Clinical Outcome

The nuclear export protein exportin-1 in solid malignant tumours: From biology to clinical trials.

Exportin-1 (XPO1), a crucial protein regulating nuclear-cytoplasmic transport, is frequently overexpressed in various cancers, driving tumor progression and drug resistance. This makes XPO1 an attractive therapeutic target. Over the past few decades, the number of available nuclear export-selective inhibitors has been increasing. Only KPT-330 (selinexor) has been successfully used for treating haematological malignancies, and KPT-8602 (eltanexor) has been used for treating haematologic tumours in clinical trials. However, the use of nuclear export-selective inhibitors for the inhibition of XPO1 expression has yet to be thoroughly investigated in clinical studies and therapeutic outcomes for solid tumours. We collected numerous literatures to explain the efficacy of XPO1 Inhibitors in preclinical and clinical studies of a wide range of solid tumours. In this review, we focus on the nuclear export function of XPO1 and results from clinical trials of its inhibitors in solid malignant tumours. We summarized the mechanism of action and therapeutic potential of XPO1 inhibitors, as well as adverse effects and response biomarkers. XPO1 inhibition has emerged as a promising therapeutic strategy in the fight against cancer, offering a novel approach to targeting tumorigenic processes and overcoming drug resistance. SINE compounds have demonstrated efficacy in a wide range of solid tumours, and ongoing research is focused on optimizing their use, identifying response biomarkers, and developing effective combination therapies. Exportin-1 (XPO1) plays a critical role in mediating nucleocytoplasmic transport and cell cycle. XPO1 dysfunction promotes tumourigenesis and drug resistance within solid tumours. The therapeutic potential and ongoing researches on XPO1 inhibitors in the treatment of solid tumours. Additional researches are essential to address safety concerns and identify biomarkers for predicting patient response to XPO1 inhibitors.

XPO1 blockade with KPT-330 promotes apoptosis in cutaneous T-cell lymphoma by activating the p53–p21 and p27 pathways

Dysregulated nuclear-cytoplasmic trafficking has been shown to play a role in oncogenesis in several types of solid tumors and hematological malignancies. Exportin 1 (XPO1) is responsible for the nuclear export of several proteins and RNA species, mainly tumor suppressors. KPT-330, a small molecule inhibitor of XPO1, is approved for treating relapsed multiple myeloma and diffuse large B-cell lymphoma. Cutaneous T-cell lymphoma (CTCL) is an extranodal non-Hodgkin lymphoma with an adverse prognosis and limited treatment options in advanced stages. The effect of therapeutically targeting XPO1 with KPT-330 in CTCL has not been established. We report that XPO1 expression is upregulated in CTCL cells. KPT-330 reduces cell proliferation, induces G1 cell cycle arrest and apoptosis. RNA-sequencing was used to explore the underlying mechanisms. Genes associated with the cell cycle and the p53 pathway were significantly enriched with KPT-330 treatment. KPT-330 suppressed XPO1 expression, upregulated p53, p21WAF1/Cip1, and p27Kip1 and their nuclear localization, and downregulated anti-apoptotic protein (Survivin). The in vivo efficacy of KPT-330 was investigated using a bioluminescent xenograft mouse model of CTCL. KPT-330 blocked tumor growth and prolonged survival (p < 0.0002) compared to controls. These findings support investigating the use of KPT-330 and next-generation XPO1 inhibitors in CTCL.

Genomic and global gene expression profiling in pediatric and young adult acute leukemia with PICALM::MLLT10 Fusion.

MLLT10 fusion is a rare but recurrent genetic driver in acute leukemias. To better understand the genomic landscape of PICALM::MLLT10 (PM) positive acute leukemia, we performed genomic profiling and gene expression profiling in twenty PM-positive patients, including AML (n = 10), T-ALL/LLy (n = 8), Mixed-phenotype acute leukemia (MPAL), T/B (n = 1) and acute undifferentiated leukemia (AUL) (n = 1). Besides confirming the known activation of HOXA, differential gene expression analysis compared to hematopoietic stem cells demonstrated the enrichment of genes associated with cell proliferation-related pathways and relatively high expression of XPO1 in PM-AML and PM-T-ALL/LLy. Our study also suggested PHF6 disruption as a key cooperating event in PICALM::MLLT10-positive leukemias. In addition, we demonstrated differences in gene expression profiles as well as remarkably different spectra of co-occurring mutations between PM-AML and PM-T-ALL/LLy. Alterations affecting TP53 and NF1, hallmarks of PM-AML, are strongly associated with disease progression and relapse, whereas EZH2 alterations are highly enriched in PM-T-ALL/LLy. This comprehensive genomic and transcriptomic profiling provides insights into the pathogenesis and development of PICALM::MLLT10 positive acute leukemia.

Androgen deprivation induces double-null prostate cancer via aberrant nuclear export and ribosomal biogenesis through HGF and Wnt activation

Androgen deprivation therapy (ADT) targeting androgen/androgen receptor (AR)- signaling pathways is the main therapy for advanced prostate cancer (PCa). However, ADT eventually fails in most patients who consequently develop castration-resistant prostate cancer (CRPC). While more potent AR antagonists and blockers for androgen synthesis were developed to improve clinical outcomes, they also show to induce more diverse CRPC phenotypes. Specifically, the AR- and neuroendocrine-null PCa, DNPC, occurs in abiraterone and enzalutamide-treated patients. Here, we uncover that current ADT induces aberrant HGF/MET signaling activation that further elevates Wnt/β-catenin signaling in human DNPC samples. Co-activation of HGF/MET and Wnt/β-catenin axes in mouse prostates induces DNPC-like lesions. Single-cell RNA sequencing analyses identify increased expression and activity of XPO1 and ribosomal proteins in mouse DNPC-like cells. Elevated expression of XPO1 and ribosomal proteins is also identified in clinical DNPC specimens. Inhibition of XPO1 and ribosomal pathways represses DNPC growth in both in vivo and ex vivo conditions, evidencing future therapeutic targets.

Co-expression analysis of transcriptomic data from cancer and healthy specimens reveals rewiring of proteasome genes and an interaction with the XPO1 gene across several tumour types

BackgroundThe 26S proteasome is a large intracellular multiprotein complex, that plays a homeostatic role by degrading proteins that have been tagged by ubiquitin. It is composed of 64 subunits assembled according to a well-defined structure and stoichiometry. Several proteasome subunits have been found to be overexpressed in tumours. However, comprehensive data are lacking on the relative abundance of each subunit and the impact on proteasome composition or stoichiometry. In cancer treatment, proteasome inhibitors and inhibitors of XPO1 (Exportin-1) have unexpectedly a similar range of activity, but the interaction between the two pathways has not been studied.MethodsWe performed gene co-expression analysis of 38 genes encoding proteasome subunits and 38 genes encoding proteins involved in nucleocytoplasmic transport in specimens from the Cancer Genome Atlas (33 tumour types) and from the Gene Tissue Expression database (32 healthy tissue types). We obtained 65 matrices, each containing Pearson correlation factors for 2964 gene pairs. We applied cluster analysis to the correlation matrices and compared the distribution of Pearson correlation coefficients of thirteen tumour types with their healthy tissue counterpart.ResultsStrong positive correlation (R Pearson correlation > 0.8) was observed for pairs of proteasome genes in the majority of healthy tissues, whereas the correlation for co-expression was significantly lower (R ≤ 0.50) for most gene pairs in the majority of cancer types. Cluster analysis based on gene co-expression allowed to distinguish cancers from healthy tissues in a clear-cut manner, and to identify the genes that contributed most to the separation. The crossed analysis between proteasome and nucleocytoplasmic transport genes showed that the expression of XPO1 and a subset of proteasome genes, including in particular PSMD14, is correlated in several cancer types and not in their healthy counterpart.ConclusionsThis analysis reveals that in cancer the co-expression of proteasome genes is significantly altered, highlighting the genes that are more often deregulated. In addition, it finds that XPO1 expression is often correlated with the expression of proteasome genes. From a therapeutic perspective, these findings support the investigation of novel targets within the proteasome and strategies of co-targeting of the proteasome and nucleocytoplasmic transport.

Nuclear to cytoplasmic transport is a druggable dependency in MYC-driven hepatocellular carcinoma

The MYC oncogene is often dysregulated in human cancer, including hepatocellular carcinoma (HCC). MYC is considered undruggable to date. Here, we comprehensively identify genes essential for survival of MYChigh but not MYClow cells by a CRISPR/Cas9 genome-wide screen in a MYC-conditional HCC model. Our screen uncovers novel MYC synthetic lethal (MYC-SL) interactions and identifies most MYC-SL genes described previously. In particular, the screen reveals nucleocytoplasmic transport to be a MYC-SL interaction. We show that the majority of MYC-SL nucleocytoplasmic transport genes are upregulated in MYChigh murine HCC and are associated with poor survival in HCC patients. Inhibiting Exportin-1 (XPO1) in vivo induces marked tumor regression in an autochthonous MYC-transgenic HCC model and inhibits tumor growth in HCC patient-derived xenografts. XPO1 expression is associated with poor prognosis only in HCC patients with high MYC activity. We infer that MYC may generally regulate and require altered expression of nucleocytoplasmic transport genes for tumorigenesis.

Xpo-1 Antagonism Transcriptionally Reprograms and Is a Therapeutic Vulnerability in GATA-3 Driven T-Cell Lymphomas

Background: The transcription factor GATA-3, via the oncogenic transcriptional program it directs, is a bona fide proto-oncogene, and thus therapeutic target, in a subset of T-cell lymphomas (TCL). The eukaryotic translation initiation factor eIF4E, in complex with helicase and scaffolding factors, facilitates 40S ribosome and Met-tRNA recruitment, both of which are rate-limiting steps in the initiation of translation. Pathways that converge on eIF4E, including PI3K/AKT/mTOR-dependent phosphorylation of 4E-BP1, are frequently activated in GATA-3 PTCL. Within the nucleus, eIF4E specifically binds oncogenic mRNAs, and then forms a complex with a co-factor (LRPPRC) and the nuclear export receptor XPO1. In contrast to bulk mRNA, these eIF4E-bound mRNA are dependent upon XPO1 for nuclear export. Therefore, as we have shown that GATA-3 is oncogenic in T-cell lymphomas (TCL), we hypothesized that selective XPO1 inhibition may transcriptionally reprogram these TCL and is a novel therapeutic vulnerability. Methods: XPO1 expression was examined by immunohistochemistry or flow cytometry in TCL specimens and in TCL that emerge in multiple genetically engineered mouse (GEM) models. Transcripts that are eIF4e clients and dependent upon XPO-1 for nuclear export were identified in an unbiased manner by eIF4e RNA immunoprecipitation (eIF4e-RIP) and RNA-seq. The extent to which XPO1 antagonism transcriptionally reprograms TCL cells, and its value as a therapeutic strategy, was examined pharmacologically with selinexor in ex vivo and in vivo studies using primary TCL specimens and GEM/PDX models, respectively. Results: Among the PTCL cases (n=53) examined, XPO1 expression was observed in 62%, and was highly expressed in CTCL, particularly in patients with large cell transformation. We sought to further understand the extent to which XPO1 expression is associated with T-cell lymphomagenesis. We utilized multiple GEM TCL models in which Smarcb1 (SNF5) or PTEN were conditionally deleted in CD4 + T cells. In both GEM models, a significant increase in XPO-1 expression was associated with the emergence of a malignant clone. A significant reduction in cell viability and increased apoptosis was observed in TCL cell lines and primary specimens treated in vitro/ex vivo with selinexor. In both GEM models, and a PDX model, selinexor treatment similarly decreased TCL progression in vivo. Given these findings, we elected to examine XPO1's potential role in transporting oncogenic, and eIF4e client, transcripts. We performed eIF4e-RIP and RNA-seq in two representative cell lines. Gene set enrichment analysis utilizing the eIF4e client RNA identified demonstrated enrichment for pathways with an established role in TCL (e.g. TCR), including GATA-3. We subsequently performed eIF4e-RIP and quantified GATA-3 transcripts by qRT-PCR in cell lines (n=4), a PDX, and in primary SS specimens (n=2). Compatible with the RNA-seq data, significant enrichment in GATA-3 transcripts was observed. These findings imply that GATA-3 transcripts are dependent upon XPO1 for nuclear export. To directly examine this, the ratio of cytoplasmic to nuclear (C:N) GATA-3 transcripts were examined by qRT-PCR in cell lines treated with selinexor. A significant decrease in the C:N ratio was observed upon XPO1 inhibition, confirming that nuclear export of GATA-3 transcripts is XPO1 dependent. We similarly examined the extent to which GATA-3 target genes are eIF4e clients and XPO1 dependent for nuclear export. We had previously described GATA-3 target genes by integrated ChIP-seq/RNA-seq. Integration of this prior dataset with our eIF4e-RIP sequencing data demonstrated that ≈21-30% of previously described GATA-3 target genes were also eIF4e clients. We selected a few such targets, including ITK, for further validation. These GATA-3 targets were eIF4e clients and dependent upon XPO1 for nuclear export. Finally, we examined expression of these proteins in a diverse panel of T-cell lymphoma/leukemia cell lines and a primary SS specimen after brief exposure to selinexor, and compatible with our findings, a significant decrease in protein expression was observed. Conclusions: Collectively then, our findings demonstrate that XPO1 antagonism, by impairing the nuclear export of both GATA-3 and many of its target gene mRNA, is a novel strategy to transcriptionally reprogram and therapeutically target GATA-3 driven TCL.

CRM1/XPO1-FOXO1 Pathway Is Associated with Clinical Outcome and Represents a Promising Target in B-Cell Acute Lymphocytic Leukemia

Background: Currently, a proportion of B-Cell Acute Lymphocytic Leukemia (B-ALL) patients still show no response to existing therapeutic drugs and existing therapeutic drugs cannot further improve the prognosis of refractory and relapsed B-ALL. Thus, the development of a new therapeutic target to battle this deadly disease is imperative. Exportin-1 (XPO1), also known as chromosomal region maintenance 1(CRM1), plays an important role in the progression of tumorigenesis. However, the prognostic and therapeutic values of XPO1 in B-ALL have not been reported. Methods: The difference in XPO1 and Foxo1 expression between normal B cells and leukemia cells was using the Human Protein Atlas (HPA) dataset and RT-qPCR results. Correlations between XPO1 expression level and clinical outcome were analyzed using the RNA-seq data of 110 newly diagnosed B−ALL patients in Nanfang Hospital. Cell proliferation assays, apoptosis assays, and cell cycle analysis were performed to analyze the anti-tumor effects of selinexor (KPT-330) in vitro. Bioinformatics analysis, western blot, and RT-qPCR were performed to explore the underlying mechanism. Results ： Higher XPO1 levels or Foxo1 levels were associated with poor prognosis in newly diagnosed B-ALL patients. Using bone marrow (BM)， peripheral blood (PB) cells from B-ALL and normal people as well as B-ALL cell lines, we found that XPO1 and Foxo1 expression was significantly increased in B-ALL patients and B-ALL cell lines. And notably, there was a positive correlation between the expression of Foxo1 and XPO1, which was verified by the data in the HPA database, and the results were consistent. Foxo1 is an important transcription factor in B-ALL, mainly localized in the nucleus, and is important for leukemia cell survival. KPT-330 (Selinexor), a selective Inhibitor of XPO1, mechanistically inhibited the expression of Foxo1, a leukemia transcription factor (reduced in both the nuclear and cytoplasmic compartments), and led to a strong repression of Foxo1 target genes associated with cell cycle, DNA replication, and transcriptional regulation. This induced growth inhibition, apoptosis, and cycle arrest in B-ALL cells. Moreover, in combination with Foxo1 Inhibitor (AS1842856), the proliferation inhibition and apoptosis-inducing effects of KPT-330 on B-ALL could be significantly enhanced. Furthermore, the KPT-330 strongly triggered apoptosis in leukemic but with minimal effects on normal cells implying that drugs of this class show promise for the targeted therapy of B-ALL leukemia cells. Conclusions: Our findings demonstrate that XPO1 is a promising prognostic indicator and a valid target for antitumor treatment with selective inhibitor KPT-330. This research was supported by the National Natural Science Foundation of China(NFSC82170163, 81970147), Clinical Study of Nanfang Hospital(LC2016ZD009/2019CR012).

Cooperative Somatic Alterations in XPO1 and TNFAIP3 (A20) Promote Immune Modulation and Tissue Infiltration in Primary Mediastinal B Cell Lymphoma

Background: Primary Mediastinal B cell lymphoma (PMBCL) is an aggressive large B cell non-Hodgkin lymphoma typically presenting as a mass in the anterior mediastinum in early adulthood, disproportionately affecting females (2:1). Previous studies have identified constitutive activation of the NF-κB pathway and immune evasion as hallmark features of PMBCL. The master negative regulator of canonical NF-κB, TNFAIP3 (A20), is inactivated in ~25-60% of PMBCL cases via disruptive mutations or deletions. Gains of the 2p16.1-15 locus ( REL, XPO1, BCL11A) are seen in ~40-75% of PMBCL cases. Interestingly, PMBCL cases with 2p16.1-15 gain/amplification display concomitant increases in XPO1 expression but lack correlative increases in REL or BCL11A. In addition, XPO1 mutations are seen in ~15-33% of PMBCL cases, with the most prevalent mutation (E571K) implicated in NF-KB activation. Despite the established occurrence of genetic events impacting XPO1 and A20 in PMBCL, the cooperative potential of these alterations remains unexplored. Consequently, we conducted an extensive review of literature describing the PMBCL genomic landscape and utilized in vivo models to examine the combined potential of XPO1 and A20 alterations to promote lymphomagenesis. Methods: Genomic data was obtained from NGS analyses from a total of 233 PMBCL patients across 6 independent published research studies and analyzed for cooccurrence of A20 &amp; XPO1 alterations (Camus et al. 2022; Chapuy et al. 2019; Lacy et al. 2020; Mareschal et al. 2015; Mottock et al. 2019; Tuveri et al 2022). For in vivo analysis, we developed a murine model of B cell specific overexpression of wildtype (WT) or E571K- XPO1 with CD19.cre driven depletion of A20 (Eµ-XPO1xA20 KO). Whole body histopathologic evaluation of FFPE tissue with H&amp;E staining was performed on 6-month-old, age and sex matched littermate mice. Results: We found co-occurrence of inactivating events in A20 and XPO1 missense mutations impacting 15% of PMBCL evaluated cases, with consistent results seen across all studies (range: 13.8-20%). As expected, A20 mutations/del were more prevalent than XPO1 mutations across all studies (OR 2.46, 95% CI 0.84-7.18, p = 0.02). XPO1 mutated cases trended towards a greater likelihood of having co-occurring A20 mutations (OR 8.51, 95% CI 0.84-86.47, p = 0.08). XPO1 mutations and gain (2p16) were found to be mutually exclusive events with gains co-occurring with A20 mutations/del in ~17% of PMBCL cases evaluated. Analysis of survival of PMBCL patients with cooccurring A20 inactivating alterations and XPO1 mutations is ongoing although preliminarily trend towards reduced mean 2-year survival (p=0.056) compared to all others are observed. Taken together, co-occurring genetic alterations effecting A20 and XPO1 are prevalent in PMBCL the alternative biology stemming from potential cooperative mechanisms may represent an aggressive subgroup of PMBCL. To evaluate concurrent B cell-specific alterations of A20 and XPO1 in vivo we utilized Eµ-XPO1xA20 KO mouse models. Performing histopathology in 6-month-old mice we observed enlarged lymph nodes due to marked increases in lymphocytes within the cortex, paracortex, medulla, and sinuses in mice with loss of functional A20, particularly in Eµ-XPO1xA20 KO mice with overexpression of WT XPO1. Increased lymphocyte populations drove overall enlargement of the node (mandibular, mesenteric, pancreatic, and mediastinal) and distorted normal architecture, featuring small lymphocytes populating sinus regions and larger lymphocytes populating areas resembling follicles. Eµ-XPO1(WT &amp; E571K)xA20 KO mice additionally featured mild mononuclear infiltrates in the lung and salivary glands; all of which were observed with increased severity compared to A20KO, Eµ-XPO1, or non-transgenic littermates. Significance: We identified co-occurring genetic lesions impacting A20 and XPO1 in PMBCL tumors and show that these alterations synergize in vivo leading to nodal/extranodal lymphocyte infiltration. The immunomodulatory effects appear to be driven by the cooperation of XPO1 overexpression, more so than mutation, and A20 inactivation in young mice. Further investigation of these models will allow elucidation of underlying cooperative mechanisms and reveal targetable pathways in PMBCL.

Xpo-1 Antagonism Impairs CSF-1R Expression and Depletes Lymphoma-Associated Macrophages in T-Cell Lymphomas

Background: Lymphoma-associated macrophages (LAM) provide ligands for antigen, costimulatory, and cytokine receptors expressed by malignant T cells and directly promote T-cell lymphomagenesis. LAM also play an important role in suppressing host anti-tumor immunity and indirectly promote T-cell lymphomagenesis. Therefore, LAM are a therapeutic vulnerability in T-cell lymphomas (TCL), and their depletion from the tumor microenvironment (TME) is a rational therapeutic goal. Methods: XPO1 and CD163 expression were examined by immunohistochemical staining. In order to determine the extent to which XPO1 antagonism depletes LAM, a pharmacologic strategy was adopted using selinexor. Viability of human monocyte-derived and TCL conditioned macrophages upon selinexor treatment was examined in vitro using standard methods. RNA binding to eIF4e was determined by RNA immunoprecipitation (RIP) using eIF4e and IgG antibodies and quantification performed by qPCR. Nuclear export of eIF4e client mRNA upon XPO1 antagonism with selinexor was examined by qRT-PCR in nuclear and cytoplasmic pools of RNA. LAM depletion upon selinexor treatment was examined in vivo using a previously described GEM ( Smarcb1-deficient) model and CD68-GFP reporter mice. Results: As we had previously demonstrated that CD163 identifies LAM that are alternatively polarized and proliferative, co-staining was performed with CD163 and XPO1, and CD163+XPO-1+ LAM identified in 69% of PTCL cases (n=26) examined. We previously demonstrated that LAM within a PTCL context are resistant to inhibition by selective CSF-1R antagonists. Therefore, we performed an unbiased, high-throughput screen using monocytes cultured in the presence of cell-free conditioned media (CFCM) obtained from T-cell lymphoma cell lines and primary specimens. This screen identified selinexor as a potential therapeutic vulnerability. Therefore, we cultured normal-donor monocytes in RPMI media alone, or in media supplemented with cell free conditioned media (CFCM) obtained from PTCL/CTCL cell lines (n=2) or primary specimens (n=5) and determined cell viability. Consistent with our prior findings, CFCM from PTCL/CTCL cells promoted the growth and survival of monocyte-derived macrophages (MDM), but this effect was abrogated upon selinexor treatment. These findings converged with the observation that CSF-1R transcripts are eIF4e clients in ALCL cells. Therefore, the extent to which transcripts required for macrophage survival (i.e. CSF-1R), proliferation (i.e. PU.1), and polarization (i.e. STAT3) are eIF4e clients was examined by eIF4e-RIP in MDM. These experiments demonstrated that CSF-1R, PU.1 and STAT3 are eIF4e clients, and selinexor treatment significantly decreased their nuclear export in MDM. Given the obvious clinical relevance of CSF-1R as a therapeutic target, CSF-1R expression in MDM following selinexor treatment was examined, and compatible with these results, a significant decrease in CSF-1R expression observed upon selinexor treatment. We previously employed CD68-GFP reporter mice in a Smarcb1-deficient GEM model, demonstrating that GFP+ macrophages in this TCL model are transcriptionally reprogrammed and proliferative. Selective CSF-1R antagonists minimally impair LAM survival in this model. In contrast, selinexor significantly depleted LAM ex vivo in this model and impaired the viability of bone marrow derived macrophages. In order to extend these findings, lymphoma-bearing GEM mice were treated with selinexor and the abundance of CD11b+Ly6G- LAM determined by flow cytometry, whereby a significant reduction in LAM abundance and TCL progression were observed, compatible with our in vitro/ex vivo findings. Conclusions: Therefore, we concluded that XPO1 inhibition indirectly impairs T-cell lymphoma growth and survival by depleting LAM, which are a dependency in these lymphomas.

Selinexor Synergizes CX4945 on Anti-Tumor Effect By Targeting XPO1/Ikros/c-Myc Signaling in T-Cell Acute Lymphoblastic Leukemia

Background Acute lymphocytic leukemia (ALL) is an aggressive hematologic malignancy with poor outcomes. The IKZF1 (Ikaros) gene plays a crucial role in normal hematopoiesis as well as acts as a leukemia suppressor in ALL. Casein kinase II (CK2) inhibitor, CX4945, has shown potential function in restoring Ikaros on transcriptional repression of target genes in ALL. Exportin-1 (XPO1) is a critical mediator of nuclear export, which is essential for regulating the cell cycle and proliferation of normal and malignant tissues. Increased expression of XPO1 has been observed in various types of cancer, including ALL. In this study, we investigated the combined effects of Selinexor and CX4945 in T-cell ALL (T-ALL) and explored the underlying mechanisms. Methods Cell Counting Kit-8(CCK-8) was used for cell viability assay, and Annexin-V/PI staining following flow cytometry analysis for apoptosis. qPCR was used for gene expression in CEM and Molt4 T-ALL cell lines. CalcuSyn analysis was performed for a synergistic effect. Results Treatment of CX4945 or Selinexor significantly led to cell proliferation arrest of CEM and Molt4 cells in a dose-dependent manner. The combination of Selinexor with CX4945 significantly enhanced the cell proliferation arrest of CEM and Molt4 cells versus the single drug controls, and CalcuSyn analysis exhibited a synergistic effect of the two drugs in the cells (Fig.1A, B). The combination also significantly increased the apoptotic cells compared to the single-drug controls (Fig.1C). c-Myc oncogene plays an essential role in human cancers. Our results showed that c-Myc mRNA level was significantly higher expressed in the cohort of T-ALL patients compared to that of normal bone marrow controls (Fig.1D). To gain insight into the underlying mechanism of the synergy, we observed the effect of the drugs on the expression of c-Myc. Results showed that the combination of Selinexor with CX4945 significantly down-regulated the expression of c-Myc compared to the single-drug controls in CEM and Molt4 cells (Fig.1E). Moreover, the combination of Selinexor with CX4945 significantly enhanced the cell growth arrest in primary cells from T-ALL patients compared to single drug controls (Fig.1F). Taken together, our data indicated the synergistic effect of Selinexor with CX4945 on cell proliferation arrest and apoptosis by down-regulation of c-Myc expression. We previously reported that Ikaros directly regulates c-Myc transcription in ALL and CX4945 suppresses c-Myc expression in a Ikaros-dependent manner. Also, c-Myc is the cargo of XPO1. Thus, our results in this study reveal a model that treatment with XPO1 inhibitor, Selinexor prevents the nuclear transport of c-Myc and leads to its nuclear accumulation and down-regulation of c-Myc expression. The combination of Selinexor and CX4945 showed the synergistic anti-tumor effect by suppressing c-Myc expression in both transcriptional and post-transcriptional levels. The mechanism model is summarized in Fig.1G. ConclusionsThe combination of Selinexor and CX4945 has synergistic effects on cell proliferation arrest and apoptosis in T-ALL by targeting the XPO1/IKROS/c-Myc signaling. Our results also provide experimental evidence for the new combination of Selinexor and CX4945 as a new potential therapeutic option for T-ALL patients.

YAP1-Dependent Promotion of Downstream Transcription through BRD4 Mediates Selinexor Resistance in Diffuse Large B-Cell Lymphoma

Background: Diffuse large B-cell lymphoma (DLBCL) represents the most prevalent subtype of non-Hodgkin lymphoma. Despite advancements in treatment, the prognosis for relapsed and/or refractory DLBCL (R/R DLBCL) patients remains unfavorable due to the development of drug resistance and disease progression. The pressing need to enhance the outcomes in R/R DLBCL patients necessitates ongoing investigations into novel therapeutic approaches. Among various exportins, the nuclear export protein exportin 1 (XPO1) solely governs the transportation of nuclear proteins harboring leucine-rich hydrophobic nuclear export signals (NES), including essential regulators like p53, RB1, and p27. Selinexor, an oral inhibitor specifically targeting XPO1, has emerged as a promising candidate in R/R DLBCL patients. Encouraging findings from a phase II clinical trial demonstrate a more favorable efficacy of Selinexor in the germinal center B-cell (GCB) subtype compared with that in other subtypes of DLBCL. Nonetheless, the clinical implementation of Selinexor has led to the emergence of acquired resistance, posing a significant challenge for medical practitioners. Efforts to overcome this resistance and establish strategies to maximize Selinexor's therapeutic potential remain of paramount importance in addressing the urgent clinical needs of R/R DLBCL patients. Methods: Characterization of Selinexor resistance targets was performed using a CRISPR/Cas9 screen transcription factors library pool at 0-day and 14-day time points after treatment. Cell function experiments in vitro were applied to verify the screening results and therapeutic efficacy was tested in vivo in NSG mice. Synergistic treatment approach utilizing BRD4 inhibitor JQ1, known for its curative effects in AML, MM, and ALL, in combination with Selinexor were also evaluated. Mechanistic exploration of BRD4's role in Selinexor resistance was further analyzed via RNA-seq, ChIP-seq, as well as luciferase reporter experiments. Therapeutic outcomes were evaluated in R/R DLBCL patients undergoing Selinexor treatment via PET/CT imaging. Results ： BRD4, BRD7, ZMYND8, and YTHDC1 were identified as top Selinexor resistance candidate targets through CRISPR/Cas9 Screen. The knock-down of BRD4 enhanced the killing ability of Selinexor in vitro and reduced tumor burden in subcutaneously transplanted tumor mice after treatment with Selinexor in vivo in DLBCL. The combined treatment with BRD4 inhibitor JQ1 and Selinexor had a stronger ability to promote cell apoptosis, enhance DNA damage and reduce nascent DNA compared with the single drug group. Hematological and organ toxicity tests confirmed an acceptable toxicity for the combined drug regimen. ChIP-seq differential peaks and RNA-seq differential genes analysis elucidated the crucial role of YAP1's sub-cellular localization under Selinexor treatment. YAP1 nuclear translocation enhanced transcription and formed an interaction with BRD4, resulting in augmented BRD4 binding domain, and finally lead to the resistance of Selinexor. PET/CT imaging showed that one patient with high XPO1 expression achieved complete response (CR), exhibiting a sensitivity to Selinexor treatment, but the other exhibits resistance associated with a lack of XPO1 expression and BRD4-regulated acetylation. Conclusions: The nuclear translocation of YAP1 and its interaction with BRD4 mediated the transcriptional regulation and further induced resistance to Selinexor in DLBCL. BRD4 inhibitor JQ1 combined with low-dose Selinexor can mitigate blood toxicity and enhance therapeutic efficacy, achieving an improved outcome.

High Rates of Remission with the Initial Treatment of Oral Selinexor Plus CHOP for Newly Diagnosed Peripheral T-Cell Lymphoma (PTCL): Clinical Outcomes Analysis of a Multi-Center Phase II Study in China

CONCLUSIONS Peripheral T-cell lymphomas (PTCLs) comprise a heterogeneous group of aggressive lymphoproliferative disorders with dismal clinical outcomes. In China, PTCLs account for over 20% of non-Hodgkin lymphoma (NHL) cases, representing a relatively high incidence. Although CHOP-like regimens remain the standard frontline therapy, their efficacy is limited (Alain Mina, 2022). Previous studies have demonstrated high expression of XPO1 in T-NHL cell lines and potent anti-proliferative effects of the selective inhibitor selinexor at nanomolar concentrations (Abeykoon JP, 2019). Here, we report the safety and preliminary efficacy of combining selinexor with CHOP as first-line treatment in previously untreated PTCL patients (ChiCTR2200057942). In this open-label, multicentre, phase 2 trial, we enrolled patients with previously untreated peripheral T-cell lymphoma (PTCL). Participants received standard CHOP chemotherapy on day 1 of each cycle for 6 or 8 cycles, along with selinexor priming at 40 or 60 mg on days 1, 8 and 15. Patients achieving a complete response (CR) or partial response (PR) at the end of induction treatement (EOI), with or without autologous stem cell transplantation (ASCT), and then received maintenance treatment with selinexor (days 1, 8, 15 and 22 every 28 days) for up to 12 months. The primary endpoint was overall response rate (ORR) during induction, and secondary endpoints included CR rate, duration of response (DOR), PFS, OS and safety. Between Jul 1, 2022 and May 21, 2023, a total of 17 previously untreated PTCL pts were enrolled and received treatment at six centers, including seven with AITL (41.2%), six with PTCL-NOS (35.3%). The median age was 52 years (range 30-67), 11 (64.7%) had stage III/IV disease, with nine (52.9%) pts having IPI 2-5. As of July 10, 2023, with a median follow-up of 7.3 months (range 1.9-14.8 months), three pts discontinued treatment without efficacy evaluation (two pts due to bone marrow suppression, one pt due to COVID-19 infection), and one pt died due to disease progression. Among 12 pts evaluable for the primary endpoint, seven pts (58.3%) achieved CR, four pts (33.3%) had PR, one pt (9.1%) experienced progressive disease (PD). Based on the analysis of different subtype, the ORR and CR was 100% (5/5) and 80% (4/5) in AITL, 100% (4/4) and 25% (1/4) in PTCL-NOS. One ALK+ALCL and one PTCL-TFH patient achieved CR, while one SPTCL patient experienced progressive disease. Among the 12 pts who received the initial dose of 60mg, two pts did not complete the third course of treatment due to myelosuppression, and two pts reduced the dose to 40mg due to adverse reactions. Five pts in the 40mg group did not require dose reduction or withdrawal. The ORR was 87.5% (7/8) and the CR rate was 62.5% (5/8) in the 60 mg group. The ORR was 100% (4/4) and the CR rate was 50% (2/4) in the 40 mg group. Pts in the 40mg group had better tolerance and similar efficacy compared to those in the 60mg group. The most common (≥10%) Grade 3 or 4 treatment-related adverse events (AEs) were neutropenia (29%), thrombocytopenia (24%), and anemia (18%). No fatal AEs were reported at the end of follow-up, the median PFS and OS were not reached. The integration of Selinexor into the standard tri-weekly CHOP chemotherapy regime has shown a manageable safety profile along with encouraging anti-tumor activity in patients with previously untreated PTCL. The trial is currently ongoing, and this manuscript presents the preliminary findings.

Coptisine inhibits the malignancy of bladder carcinoma cells and regulates XPO1 expression.

This work is performed to investigate the effect of coptisine (COP) on the malignant biological behaviors of bladder carcinoma cells and its underlying mechanism. Bladder carcinoma cell lines were treated with different concentrations of COP in vitro. Cell counting kit-8 (CCK-8), scratch healing assay, Transwell assay, and flow cytometry were used to detect cell growth, migration, invasion, and cell cycle progression. Bioinformatics analysis was performed to predict the molecular targets of COP. Quantitative real-time PCR and western blot were adopted to determine the expression levels of exportin 1 (XPO1) mRNA and protein, respectively. Gene set enrichment analysis was applied to predict the signaling pathways related to XPO1. This study showed that COP treatment markedly suppressed the malignant biological behaviors of bladder carcinoma cells. XPO1 was identified as a downstream molecular target of COP in bladder carcinoma, and COP treatment inhibited the expression of XPO1 in bladder carcinoma cell lines. Overexpression of XPO1 reversed the impacts of COP on the malignant biological behaviors of bladder carcinoma cells. COP treatment modulated the expression level of cyclin D1 and CYP450 via XPO1. In summary, COP represses the malignant biological behaviors of bladder carcinoma cells and regulates XPO1 expression, which is promising to be a complementary drug for bladder carcinoma treatment.

Correlation of comprehensive molecular mapping of pancreatic ductal adenocarcinoma with XPO1 mRNA expression levels to potential clinical targets.

4144 Background: Encouraging pre-clinical efficacy targeting Exportin-1 (XPO1) - a master regulator of tumor suppressor protein export - has been reported in pancreatic ductal adenocarcinoma (PDAC) and clinical trials are currently ongoing. However, limited data is available regarding expression and function of XPO1 in PDAC. Thus, we investigated XPO1 mRNA expression and its clinical and immune correlates in PDAC. Methods: 5,488 PDACs were tested at Caris Life Sciences (Phoenix, AZ) with NGS of DNA (WES) and RNA (WTS) . TMB-H was defined as ≥10 mutations/MB. The cohort was stratified in quartiles according to XPO1 mRNA expression status, and XPO1-high ( XPO1H) and XPO1-low ( XPO1L) expression were defined as ≥top and &lt;bottom quartile of transcripts per million (TPM). Immune cell fraction was calculated by QuantiSeq method. Gene expression profiles were analyzed for transcriptomic signatures predictive of response to immune checkpoint inhibitors (T cell-inflamed score) and MAPK pathway activation (MPA). The Mann-Whitney U and X2 tests were applied as appropriate, with p-values adjusted for multiple comparisons. Real-world overall survival (OS) data was obtained from insurance claims. TGCA data were used to validate molecular, biological and immunological findings. Single-cell RNA analyses on a publicly available dataset were performed to elaborate cellular localization of XPO1. Results: Increased XPO1 mRNA expression was observed in metastatic lesions compared to primary tumors (p&lt;0.001). Copy number amplification and mutation prevalence was comparable between XPO1H and XPO1L samples (p&gt;0.05), along with similar rates of MSI-H/dMMR (1.3 vs 0.9%) and TMB-H (2.0 vs 1.3%; p&gt;0.05). XPO1H PDACs were associated with a significant higher prevalence of T cell-inflamed tumors compared to XPO1L cases (58 vs 5%; p&lt;0.05), consistent with higher immune cell infiltration in the XPO1H quartile as compared to XPO1L (p&lt;0.05), except for immunosuppressive regulatory T cells and monocytes (p&gt;0.05). XPO1H was associated with a higher MPA score as compared to XPO1L (2.4 vs -2.1 Arbitrary Units; p&lt;0.05). XPO1H was associated with shorter OS (HR 1.09 [1.1-1.4], p=0.048). Validation studies using TCGA datasets corroborate our findings and confirmed increased immune cell infiltration as a function of XPO1. Moreover, single cell data revealed predominant and high expression of XPO1 in the tumor cell compartment. Conclusions: This is the first study comprehensively mapping XPO1 mRNA expression and immune-correlates in PDAC. We found that high XPO1 is linked to increased immune cell infiltration with a T cell-inflamed pattern. Our data provided a potential rationale to combine immune checkpoint therapy (+/- XPO1 inhibitors) in XPO1H PDACs.

17th International Conference on Malignant Lymphoma, Palazzo dei Congressi, Lugano, Switzerland, 13 - 17 June, 2023.

Introduction: The prognosis of R/R PTCLs is very poor. Selinexor is an oral, first in class, potent selective inhibitor of nuclear exportin, that shown promising overall response rate (ORR) and complete response (CR) in a phase I study of selinexor in combination with high-dose dexamethasone, ifosfamide, carboplatin and etoposide in R/R PTCLs, Tang et al (Haematologica 2021). These results are very preliminary and need to be confirmed; for this reason, we designed the PTCL S-IDE study (EudraCT number 2021-006229-23). Methods: S-IDE is a phase II multicenter pilot study of Selinexor in combination with Ifosfamide, Etoposide and Dexamethasone in patients with R/R PTCLs. We decided to omit carboplatin in order to reduce nausea and hematologic toxicity, in addition the activity of carboplatin in PTCL is uncertain. Key inclusion criteria are: age 18–75 years, R/R histologically confirmed PTCL (PTCL-NOS, angioimmunoblastic T cell lymphoma - AITL, anaplastic large cell ALK negative—ALK neg, T-helper follicular—TFH) after at least one course of anthracycline containing regimen chemotherapy (including or not high dose chemotherapy and stem cell transplantation - SCT), PS ECOG ≤2, adequate organ function. All patients will receive intravenous S-IDE on a 21-day cycle: Selinexor (40 mg on day 3, 5 and 7); Ifosfamide 5 g/mq on day 2; Etoposide 100 mg/mq on days 1–3; Dexamethasone 20 mg/day on days 3–7. Patient in CR at the end of the 4 courses receive a maintenance with selinexor (selinexor 60 mg weekly, until progression or unacceptable toxicity) or proceed to allo-SCT or auto-SCT according to donor availability, patient age and comorbidities. The primary endpoint is ORR at the end of 4 courses of S-IDE; the secondary endpoints are duration of response, 18-months PFS and OS, treatment related mortality, CR by histotypes, rate of patients able to undergo SCT, and adverse events. Exploratory biological analyses are ORR in subgroups based on GATA3 and TBX21 expression; loss of tumor suppressor genes on the CDKN2A/B-TP3 axis and PTEN-PI3K pathways as well as genetic gains and amplification of STAT3 and MYC; the presence of mutations described as associated with a poor prognosis, including CD28 mutations in AITL; TP63 rearrangement, loss of TP53, and loss of PRDM1 in ALK− ALCL; GATA3 , TP53, and/or CDKN2A in ALK− ALCL; and alterations in histone methyltransferase genes KMT2A, KMT2B, or KDM6A and FAT1 in PTCL-NOS; XPO1 expression; circulating tumor DNA (ctDNA). The sample size is 30 patients, with enrollment 18 months in 9 Italian centers. The sample size calculation refers to the primary endpoint; a sample size of 30 patients will allow to achieve a statistical power of more than 90% (94%) to test an increase of 30% of ORR (from 50% under null hypothesis to 80% under the alternative one) using a two-sided one sample binomial test with alpha =5%. The accrual is ongoing; at the end of February 2023, 2 patients have been enrolled. Keywords: aggressive T-cell non-Hodgkin lymphoma, combination therapies, ongoing trials Conflicts of interests pertinent to the abstract. A. Chiappella Consultant or advisory role Celgene-BMS, Gilead-Sciences, Ideogen, Janssen, Roche, SecuraBIO, Takeda Other remuneration: Lecture fees/Educational activities: Astrazeneca, Celgene-BMS, Gilead-Sciences, Incyte, Janssen-Cilag, Novartis, Roche, Takeda