Molecular Mechanistic Insights and Real-World Clinical Outcomes of Selinexor in Diffuse Large B-Cell Lymphoma

INTRODUCTION

Selinexor, a novel small molecule XPO1 inhibitor and selective inhibitor of nuclear export (SINE), has been approved by the FDA for the treatment of multiple myeloma and relapsed or refractory DLBCL in patients who have received at least two prior lines of therapy. Despite its significant efficacy in the treatment of DLBCL, the specific mechanisms of Selinexor remain unclear. In this study, we aim to combine clinical patient data with cellular-level experiments to detect and validate the impact of Selinexor on the prognosis of DLBCL patients, as well as its regulatory effects on gene transcription and protein levels in GCB and ABC DLBCL cell lines. AIM The objective of this study is to assess the effectiveness and survival outcomes of Selinexor therapy in lymphoma patients at our medical facility, as well as to identify prognostic factors. Additionally, we aim to investigate the cellular-level inhibitory effects of Selinexor on DLBCL cell lines and the underlying mechanisms of action.

METHOD

1. A retrospective study was conducted to analyze the clinical characteristics and treatment outcomes of 36 lymphoma patients who received Selinexor treatment at the Hematology Department of the Fourth Hospital of Hebei Medical University from June 2021 to December 2023. The data was collected and analyzed using univariate analysis through the Kaplan-Meier method, and prognostic factors were determined by the Cox proportional hazard regression model. This study aimed to provide insights into the clinical efficacy of Selinexor in treating lymphoma patients.

2. The induction of apoptosis and cell cycle arrest in DLBCL cells by Selinexor was evaluated by flow cytometry. RNA-seq and proteomics sequencing were utilized to detect variations in transcription and protein levels of related genes in both GCB (SU-DHL6) and ABC (OCI-LY3) DLBCL cell lines after Selinexor treatment. The alteration from transcriptional and protein expression level was verified using qRT-PCR, d-PCR, and Western blot analysis.

RESULTS

1. In a cohort of 25 DLBCL patients treated with Selinexor, Kaplan-Meier and Cox regression model analyses revealed that both GCB subtypes and treatment line were adverse factors affecting OS and PFS.

2. Flow cytometry results indicated that the Selinexor significantly induced apoptosis and caused G1 phase cell cycle arrest in DHL6 and LY3 cells.

3. RNA-seq analysis revealed significant differences in the transcription levels of 2048 genes in DHL6 cells treated with Selinexor, including 865 upregulated genes and 1183 downregulated genes. Proteomics sequencing showed that 233 proteins were differentially expressed, with 79 upregulated and 154 downregulated. Similarly, in LY3 cells treated with Selinexor, there were 2015 significant differentially expressed genes, including 941 upregulated genes and 1074 downregulated genes. Proteomics sequencing showed that 212 proteins were differentially expressed, with 135 upregulated and 77 downregulated.

4. qRT-PCR and Western blot analysis confirmed that Selinexor significantly downregulated the transcription and protein levels of GTSE1, RRM2, CKS1B, and PCNA. Among transcription levels in DHL6 and LY7 cell lines, Selinexor only downregulated CD48, GMNN, CENPM, and PCLAF. Both of these cell lines are GCB DLBCL cell lines. In ABC DLBCL, d-PCR and qRT-PCR were used to confirm that Selinexor could upregulate S100A11 and TRIM22 expression and downregulate RRM2, CENPM, GMNN, CD48, CKS1B, and SLC1A5 expression at the transcription level. Furthermore, a decrease in the protein level of TRIM22 was observed by Western blot in LY3 cells.

CONCLUSION

1. The safety of Selinexor during application is manageable. Patients who received Selinexor as a second or third line treatment achieved the best therapeutic outcomes. Additionally, patients with the non-GCB subtype exhibited better efficacy than those with the GCB subtype.

2. The mechanism of Selinexor in inhibiting GCB and ABC DLBCL cell proliferation is associated with its ability to impact genes involved in cell cycle interruption and apoptosis promotion, while downregulating genes involved in immune regulation and iron metabolism.

No relevant conflicts of interest to declare.