The molecular mechanism and challenge of targeting XPO1 in treatment of relapsed and refractory myeloma

Association of non-gain-of-function alterations in exportin-1 with improved overall survival in colorectal cancer

BACKGROUND

Upregulation of nuclear export protein exportin-1 (coded by gene XPO1) has been previously demonstrated in multiple cancer subtypes, contributing to pharmacotherapy resistance and increased recurrence rates. This study aimed to explore the effect of non-gain-of-function (GOF) XPO1 alterations in patients with colorectal cancer (CRC).

METHODS

Patients with colon/rectal/colorectal adenocarcinoma were identified from the Memorial Sloan Kettering Clinicogenomic, Harmonized Oncologic Real-World Dataset using cBioPortal. A subpopulation with alterations in XPO1 was identified. Patients with known amplifications and GOF E571K and R749Q alterations were excluded, as were patients with in situ and stage IV disease. Survival analysis was performed via Kaplan-Meier and Cox proportional hazards analyses, adjusted for patient age and disease stage.

RESULTS

Among 5543 patients with CRC, 83 (1.5%) had alterations in the XPO1 locus, and 5460 patients (98.5%) did not. Of patients with XPO1 alteration, 66 (79.5%) had non-GOF alterations, and 17 (21.5%) had GOF point mutations or amplifications. Patients with non-GOF XPO1 alteration had a mortality hazard ratio of 0.601 (95% CI, 0.463-0.805; P =.011). When adjusted for patient age and disease stage, XPO1 co-alteration was associated with improved overall survival (OS) in patients with alterations in TP53, APC, FBXW7, SMAD4, and BRAF genes (all P <.01).

CONCLUSION

XPO1 alterations were associated with improved OS in patients with CRC. Associated survival benefits persisted when co-alterations were present, particularly in co-alterations with intranuclear tumor suppressor proteins.

Multiomics Analysis of Exportin Family Reveals XPO1 as a Novel Target for Clear Cell Renal Cell Carcinoma

Background: Recently, exportin gene family members have been demonstrated to play essential roles in tumor progression. However, research on the clinical significance of exportin gene family members is limited in clear cell renal cell carcinoma (ccRCC). Methods: Pan-cancer data, ccRCC multiomics data, and single-cell sequence were included to analyze the differences in DNA methylation modification, single nucleotide variations (SNVs), copy number variations (CNVs), and expression levels of exportin gene family members. Non-negative matrix factorization was used to identify molecular subtypes based on exportin gene family members, and the prognostic and biological differences of different molecular subtypes were compared across multiple dimensions. Results: Exportin gene family members were upregulated in pan-cancer expression, and their aberrant expression was significantly influenced by DNA methylation, SNV, and CNV, particularly in ccRCC. Based on the expression matrix of exportin gene family members, two molecular subtypes, exportin famliy genes (XPO)-based subtype 1 (XPS1) and exportin famliy genes (XPO)-based subtype 2 (XPS2), were identified. The expression levels of exportin gene family members in the XPS2 subtype were significantly higher than those in XPS1, and the prognosis was poorer. The XPS2 subtype had lower immune component abundance and higher immune exhaustion scores. Its response rate to immunotherapy was significantly lower than that of the XPS1 subtype, but it was more sensitive to small molecules, including mercaptopurine and nutlin. Among them, exportin-1 (XPO1) is a potential diagnostic and therapeutic target for ccRCC, which can promote renal cancer progression by activating the PI3K-AKT-mTOR (phosphatidylinositol 3-kinase (PI3K)/AKT serine/threonine kinase (AKT)/mechanistic target of rapamycin (MTOR)) and interferon alpha pathways. Conclusion: This study analyzed the variations of exportin gene family members at the pan-cancer level and identified two distinct ccRCC subtypes, which can guide personalized management of patients.

Prognostic and functional role of the nuclear export receptor 1 (XPO1) in gastrointestinal cancers: a potential novel target?

In the last decades the survival of metastatic gastrointestinal (GI) cancer patients could have been significantly extended due to the introduction of targeted- and immunotherapy. However, only the minority of patients will experience long-lasting survival. Hence, novel therapeutics are clearly necessary for GI cancer patients. Molecular high-throughput profiling techniques have revealed potential novel targetable molecular alterations, emphasizing the necessity for tailored therapeutic approaches. Nuclear export proteins, particularly Exportin-1 (XPO1), have emerged as promising targets in cancer therapy due to their crucial role in cellular homeostasis and regulation of key cellular functions. Dysregulation of XPO1-mediated nuclear export leads to the functional loss of tumor suppressors and pro-apoptotic factors, facilitating cancer progression. Selinexor, a XPO1 inhibitor, has shown promising activity in preclinical and clinical studies, particularly in hematological malignancies. However, its efficacy in GI cancers remains underexplored. This review aims to elucidate the functional and pathophysiological role of XPO1 in GI cancers. Despite the potential of XPO1 inhibitors in suppressing cell proliferation and inducing apoptosis, comprehensive molecular landscape data and validation of selective inhibitors in GI cancers are lacking. Targeting XPO1 presents a significant therapeutic potential for the treatment of GI cancer patients. Further research is necessary to fully elucidate the molecular landscape according to XPO1 expression in GI tumors and to validate the efficacy of selective XPO1 inhibitors. These efforts are expected to contribute to the development of more effective and personalized therapeutic strategies for GI cancer patients.

Efficacy and safety of selinexor for patients with relapsed and refractory multiple myeloma: A meta-analysis

PURPOSE

Selinexor is a first-in-class, oral selective-inhibitor-of-nuclear-export, granted accelerated approval by FDA (2019) for relapsed and refractory multiple myeloma (RRMM). We sought to quantitatively summarize the selinexor efficacy and safety in RRMM.

METHODS

We searched PubMed, EMBASE, CENTRAL, clinicaltrial.gov, and google scholar, until May 2023, studies about selinexor use in RRMM. The outcome measures of interest were primarily efficacy outcomes, in addition to safety outcomes. Random-effect model analyses were performed, at statistical significance of P<0.05, using the RevMan software.

RESULTS

Meta-analyses of eleven included clinical trials yielded a significant 56.21% overall clinical benefit, 46.91% overall response, 4.89% complete response, 23.41% very good partial response, 24.68% partial response, and 28.06% stable disease rates with selinexor. Due to safety reasons, selinexor caused significant increase in discontinuation rate, 16.80%. Subgroup analyses demonstrated higher efficacy with selinexor plus dexamethasone and proteasome inhibitor combinations than with selinexor alone. The multiple myeloma type, high cytogenetic risk, refractory state, and advanced disease state did not affect performance. Risk of selection, performance, and detection biases were unclear in the included trials.

CONCLUSION

Selinexor led to significant positive responses with an acceptable safety profile in RRMM patients, despite higher rates of safety-related discontinuations. Selinexor-based combinations further enhanced response.

Real World Efficacy and Toxicity of Selinexor: Importance of Patient Characteristics, Dose Intensity and Post Progression Outcomes

BACKGOUND

Selinexor is an orally available selective inhibitor of exportin-1 that has offered a new treatment option in relapsed or refractory myeloma (RRMM) either in combination with dexamethasone (Sd) or with bortezomib and dexamethasone (SVd).

PATIENTS-METHODS

We evaluated the efficacy and toxicity of selinexor combinations in the real world, post progression therapies and their outcomes. The analysis included 44 patients with RRMM treated with Sd (N = 21, 48%) or SVd (N = 23, 52%).

RESULTS

On intent-to-treat, response rate (ORR) among all treated patients was 29.5% (13/44, of which CR: 2, VGPR: 3, PR:8); ORR was 35% for SVd and 24% for Sd. Median PFS was 3.0 months for all; 6.9 months for responders (≥PR),2.7 months for Sd and 3.4 months for SVd treated patients. In univariate analysis, serum albumin <3.5 g/dl and LDH >ULN were associated with worse PFS (P = .001 and P = .032, respectively).The OS of the whole cohort exceeded one year while serum albumin <3.5 gr/dl and LDH>ULN were associated with worse OS. After progression to Sd/SVd, 20 patients received further therapy; on ITT, the ORR was 40% (8/20) and the subsequent PFS was 3.4 months. The most common adverse events were fatigue, thrombocytopenia and nausea, while the most recorded grade 3 or 4 side effect was thrombocytopenia; 56% (25/44) of patients required dose reduction, however, this was not associated with inferior PFS.

CONCLUSION

In conclusion, selinexor-based therapy provides an additional treatment option in the real word setting and with appropriate dosing and toxicity management a subset of patients may have significant benefit.

Selinexor: Targeting a novel pathway in multiple myeloma

Selinexor is an orally bioavailable selective inhibitor of nuclear export compound that inhibits exportin-1 (XPO1), a novel therapeutic target that is overexpressed in multiple myeloma (MM) and is responsible for the transport of ∼220 nuclear proteins to the cytoplasm, including tumour suppressor proteins. Inhibition of this process has demonstrated substantial antimyeloma activity in preclinical studies, both alone and in combination with established MM therapeutics. Based on a clinical trial programme encompassing multiple combination regimens, selinexor-based therapy has been approved for the treatment of relapsed/refractory MM (RRMM), with selinexor-dexamethasone approved in the later-relapse setting for penta-refractory patients and selinexor-bortezomib-dexamethasone approved for patients who have received ≥1 prior therapy. Here, we provide a comprehensive review of the clinical data on selinexor-based regimens, including recent updates from the 2022 American Society of Hematology annual meeting, and summarise ongoing studies of this novel targeted agent in newly diagnosed MM and RRMM.

Nuclear Export Inhibitor Selinexor Enhances Oncolytic Myxoma Virus Therapy against Cancer

Oncolytic viruses exploited for cancer therapy have been developed to selectively infect, replicate, and kill cancer cells to inhibit tumor growth. However, in some cancer cells, oncolytic viruses are often limited in completing their full replication cycle, forming progeny virions, and/or spreading in the tumor bed because of the heterogeneous cell types within the tumor bed. Here, we report that the nuclear export pathway regulates oncolytic myxoma virus (MYXV) infection and cytoplasmic viral replication in a subclass of human cancer cell types where viral replication is restricted. Inhibition of the XPO-1 (exportin 1) nuclear export pathway with nuclear export inhibitors can overcome this restriction by trapping restriction factors in the nucleus and allow significantly enhanced viral replication and killing of cancer cells. Furthermore, knockdown of XPO-1 significantly enhanced MYXV replication in restrictive human cancer cells and reduced the formation of antiviral granules associated with RNA helicase DHX9. Both in vitro and in vivo, we demonstrated that the approved XPO1 inhibitor drug selinexor enhances the replication of MYXV and kills diverse human cancer cells. In a xenograft tumor model in NSG mice, combination therapy with selinexor plus MYXV significantly reduced the tumor burden and enhanced the survival of animals. In addition, we performed global-scale proteomic analysis of nuclear and cytosolic proteins in human cancer cells to identify the host and viral proteins that were upregulated or downregulated by different treatments. These results indicate, for the first time, that selinexor in combination with oncolytic MYXV can be used as a potential new therapy.

Significance

We demonstrated that a combination of nuclear export inhibitor selinexor and oncolytic MYXV significantly enhanced viral replication, reduced cancer cell proliferation, reduced tumor burden, and enhanced the overall survival of animals. Thus, selinexor and oncolytic MYXV can be used as potential new anticancer therapy.

Diagnostic and Prognostic Profiling of Nucleocytoplasmic Shuttling Genes in Hepatocellular Carcinoma

One of the key features of eukaryotic cells is the separation of nuclear and cytoplasmic compartments by a double-layer nuclear envelope. This separation is crucial for timely regulation of gene expression, mRNA biogenesis, cell cycle, and differentiation. Since transcription takes place in the nucleus and the major part of translation in the cytoplasm, proper distribution of biomolecules between these two compartments is ensured by nucleocytoplasmic shuttling proteins - karyopherins. Karyopherins transport biomolecules through nuclear pores bidirectionally in collaboration with Ran GTPases and utilize GTP as the source of energy. Different karyopherins transport different cargo molecules that play important roles in the regulation of cell physiology. In cancer cells, this nucleocytoplasmic transport is significantly dysregulated to support increased demands for the import of cell cycle-promoting biomolecules and export of cell cycle inhibitors and mRNAs. Here, we analysed genomic, transcriptomic and proteomic data from published datasets to comprehensively profile karyopherin genes in hepatocellular carcinoma. We have found out that expression of multiple karyopherin genes is increased in hepatocellular carcinoma in comparison to the normal liver, with importin subunit α-1, exportin 2, importin subunit β-1 and importin 9 being the most over-expressed. More-over, we have found that increased expression of these genes is associated with higher neoplasm grade as well as significantly worse overall survival of liver cancer patients. Taken together, our bioinformatic data-mining analysis provides a comprehensive geno-mic and transcriptomic landscape of karyopherins in hepatocellular carcinoma and identifies potential members that could be targeted in order to develop new treatment regimens.