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

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.