Selective Inhibitor Of Nuclear Export Research Articles

Efficacy of verdinexor for the treatment of naïve canine epitheliotropic cutaneous T-cell lymphoma: An open-label pilot study.

Verdinexor (Laverdia-CA1; Dechra Veterinary Products), a selective inhibitor of nuclear export, has been utilised for treatment of non-Hodgkin T-cell lymphoma in dogs. However, the efficacy of verdinexor has not been evaluated for cutaneous epitheliotropic T-cell lymphoma (CETL). To evaluate the efficacy of verdinexor for the treatment of CETL. Eight client-owned animals with CETL. Patients received between 1.28 and 1.45 mg/kg verdinexor per os twice weekly with a minimum of 72 h between doses until disease progression or voluntary withdrawal. Adjunctive therapy with lokivetmab or prednisone was permitted after Day (D)14. Assessment of clinical lesions (canine Response Evaluation Criteria in Solid Tumors [cRECIST v1.0] and novel Canine Epitheliotropic Lymphoma Extent and Severity Index [CELESI]), pruritus (Visual Analog Scale) and treatment efficacy (owner global assessment of treatment efficacy [OGATE]) were evaluated every 14 days for 3 months, then monthly thereafter (mean 70 ± 43.4 days). Seventy-five percent of patients achieved complete response, partial response or stable disease. The mean time to disease progression was 56 ± 41 days. There was a significant reduction (p = 0.026) in total CELESI score when the lowest score for each dog was compared to their score at D0. Verdinexor did not significantly reduce pruritus at any time point (p = 0.45), including when given as a monotherapy or concurrently with lokivetmab ± glucocorticoids. On D28, 75% of owners rated response to treatment as 'fair' to 'excellent'. The most common adverse effects included weight loss, inappetence, vomiting and lethargy. Verdinexor could be considered a safe, palliative treatment for canine CETL.

Recent Updates in the Diagnosis and Management of Kidney Diseases in Multiple Myeloma

Multiple myeloma (MM) represents a difficult-to-treat plasma cell malignancy and the second most common hematologic malignancy in adults, significantly impacting kidney function. The spectrum of kidney involvement in MM is broad, encompassing electrolyte imbalances, tubular injury, and even rare glomerular diseases. The evolution of MM treatment modalities has led to notable improvements in the long-term survival of patients experiencing kidney-related complications. Over the past decade, groundbreaking therapeutic agents have emerged, including proteasome inhibitors, immunomodulatory drugs, anti-CD38 monoclonal antibodies, selective inhibitors of nuclear export, and antibody-drug conjugates. These novel therapies have revolutionized the landscape of MM management, offering new hope for patients and challenging the traditional treatment paradigms. This comprehensive review explores recent advances in the diagnosis and management of MM, emphasizing the pivotal role of these innovative therapeutic agents in improving patient outcomes. We delve into the intricacies of diagnosing MM, highlighting the significance of early detection and precise diagnostic tools. We elucidate the evolving treatment strategies, emphasizing the mechanisms of action and clinical efficacy of the latest agents. This manuscript provides valuable insights into the ever-evolving field of MM management, shedding light on the remarkable progress achieved in enhancing the prognosis and quality of life of MM patients.

Electrophile Determines Cellular Phenotypes among XPO1-Targeting Small Molecules.

Covalent drug discovery has experienced a renaissance, with numerous electrophilic small molecules recently gaining FDA approval. Many structurally diverse electrophilic small molecules target exportin-1 (XPO1/CRM1) at cysteine 528, including the selective inhibitor of nuclear export (SINE) selinexor, which was FDA-approved as an anticancer agent in 2019. Emerging evidence supports additional pharmacological classes of XPO1 modulators targeting Cys528, including the selective inhibitors of transcriptional activation (SITAs) and probes that induce rapid degradation of XPO1. Here, we analyzed structure-activity relationships across multiple structural series of XPO1 Cys528-targeting probes. We observe that the electrophilic moiety of Cys528-targeting small molecules plays a decisive role in the cellular behavior observed, with subtle changes in electrophile structure being sufficient to convert XPO1-targeting probes to different pharmacological classes. This investigation represents a unique case study in which the electrophile functionality used to target a specific cysteine determines the pharmacological effect among diverse XPO1-targeting small molecules.

Beyond oncology: Selinexor's journey into anti-inflammatory treatment and long-term management.

Selinexor, a selective inhibitor of nuclear export (SINE), is gaining recognition beyond oncology for its potential in anti-inflammatory therapy. This review elucidates Selinexor's dual action, highlighting its anti-tumor efficacy in various cancers including hematologic malignancies and solid tumors, and its promising anti-inflammatory effects. In cancer treatment, Selinexor has demonstrated benefits as monotherapy and in combination with other therapeutics, particularly in drug-resistant cases. Its role in enhancing the effectiveness of bone marrow transplants has also been noted. Importantly, the drug's impact on key inflammatory pathways provides a new avenue for the management of conditions like sepsis, viral infections including COVID-19, and chronic inflammatory diseases such as Duchenne Muscular Dystrophy and Parkinson's Disease. The review emphasizes the criticality of managing Selinexor's side effects through diligent dose optimization and patient monitoring. Given the complexities of its broader applications, extensive research is called upon to validate Selinexor's long-term safety and effectiveness, with a keen focus on its integration into clinical practice for a diverse spectrum of disorders.

Abstract 4530: Nuclear export inhibitor cooperates with PARP inhibitor to suppress the growth of metastatic castration resistant prostate cancer in vivo

Abstract Background: Aberrant nuclear protein transport, often observed in cancer, causes mislocalization-dependent inactivation of critical cellular proteins. Earlier we showed that overexpression of nuclear export protein exportin 1 (XPO1) is linked to higher grade and Gleason score in metastatic castration resistant prostate cancer (mCRPC). The network topology computational approach (NTCP) determined a higher synthetic lethal score between XPO1 and poly (ADP-ribose) polymerase (PARP1). We showed that selective inhibitor of nuclear export (SINE) could synergized with PARP inhibitors in mCRPC cell lines. Here we evaluated the efficacy of SINE and PARP inhibitor (PARPi) combination in cell line derived as well as patient derived xenograft (CDX and PDX) models and deciphered the mechanism of synergy. Methods: For CDX model, the 22rv1 mCRPC cells were grown as subcutaneous xenografts in ICR-SCID male mice. For PDX model, tissue was collected from Champions Oncology (CTG-3581) and grown subcutaneously in CEIA/NOG male mice. SINE dosed orally at 10-15 mg/kg twice a week and PARPi dosed orally at 50 mg/kg daily. For in vitro mechanistic study, 22rv1 cells were subjected to RNAseq and proteomic analysis after treatment. Data analysis was performed using iPathwayGuide (advaitabio.com). Results: The CDX and PDX showed pronounced anti-cancer efficacy by this combination compared to single agents without any significant weight loss. Survival analysis in CDX model demonstrated enhanced benefits to the mice of combination group. Immunohistochemistry (IHC) revealed apoptotic cell death in the combination group which is evident from cleaved caspase 3 staining and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL). To decipher the mechanism of synergy we performed transcriptomic (RNAseq) and proteomic analysis in vitro. We observed downregulation of DNA replication related gene minichromosome maintenance complex component 6 (MCM6) and cell division cycle 6 (CDC6) in the combination treatment. Gene set enrichment analysis (GSEA) also showed low enrichment scores for DNA replication. Proteomic analysis revealed a down regulation of DNA replication modulators such as HMGB2 and DNAJC9 which work on DNA coiling and histone respectively. Conclusions: Taken together, this study revealed the therapeutic potential of SINE-PARPi combination via targeting DNA damage response pathway in mCRPC. Further evaluation of molecular synergy in the xenograft models are underway through RNA interference (RNAi) technique and Digital Spatial Profiling (DSP). Citation Format: Md Hafiz Uddin, Amro Aboukameel, Husain Y. Khan, Sahar F. Bannoura, Frank Cackowski, Rafic Beydoun, Gregory Dyson, Seongho Kim, Julie Boerner, Vinod Shidham, Ramzi M. Mohammad, Boris C. Pasche, Asfar S. Azmi, Elisabeth I. Heath. Nuclear export inhibitor cooperates with PARP inhibitor to suppress the growth of metastatic castration resistant prostate cancer in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4530.

Abstract 2086: Effect of XPO1 inhibition on colorectal cancer tumorigenesis

Abstract Colorectal Cancer (CRC) is the second leading cause of cancer-related death in the U.S. A subset of individuals faces a notably higher likelihood of developing CRC within their lifetime. Hence, there is a compelling need for innovative chemopreventive treatments aimed at minimizing CRC tumorigenesis. Exportin 1 (XPO1; also referred to as CRM1) plays a pivotal role in transporting proteins from the nucleus to the cytoplasm. The overexpression of XPO1 has been identified across several cancers, including CRC. XPO1 interacts with a diverse spectrum of more than 1000 proteins. The overexpression of XPO1 leads to the excessive removal of tumor suppressors from the nucleus, rendering these proteins functionally inert. To counteract the overexpression of XPO1 in tumors, a novel class of drugs known as Selective Inhibitors of Nuclear Export (SINE) has been developed. Among these, Eltanexor (KPT-8602) has emerged as a promising therapeutic agent, demonstrating fewer side effects compared to its precursors, and is currently under evaluation in Phase 1/2 clinical trials. The treatment effects of SINE compounds on CRC remain largely unknown. We have assessed Eltanexor's ability to limit CRC tumorigenesis using a genetic CRC model in Apcmin/+ mice. Our findings indicate that Eltanexor substantially reduces tumor burden by approximately 3-fold and induces a significant reduction of tumors exceeding 1mm in size. Furthermore, a xenograft experiment using the human CRC cell line, HCT116, reveals nearly a 3-fold reduction in tumor size upon Eltanexor treatment. In both CRC models, Eltanexor exhibits noteworthy tolerability. Additionally, XPO1 protein levels are consistently diminished in both models, aligning with our in vitro observations. To further ascertain Eltanexor's specificity for CRC tumors versus normal tissue, we conducted drug sensitivity assays using organoids derived from Apcmin/+ tumors and wild-type mice small intestine tissue. We found that Apcmin/+ tumoroids have heightened sensitivity to Eltanexor-treatments, when compared to wild-type organoids. In an endeavor to elucidate Eltanexor's potent in vivo tumorigenesis inhibitory effects, we conducted multiple assays which revealed a reduction in COX-2 RNA and protein expression levels in Eltanexor-treated cells and reduced COX-2 protein in the tumors of Eltanexor-treated Apcmin/+ mice. In CRC, COX-2 is implicated in CRC development and is currently the target of multiple CRC chemopreventive agents. Our observations reveal that Eltanexor-treated CRC cells exhibit reduced COX-2 gene expression through both inhibiting COX-2’s promoter and its mRNA post-transcriptional stability. Collectively, our findings underscore XPO1 as a potent target for inhibiting CRC tumorigenesis. Future studies will aim to further assess how Eltanexor is impacting COX-2’s promoter, while additionally testing Eltanexor’s tumorigenesis-inhibiting potential in a colitis-induced CRC mouse model. Citation Format: Andrew E. Evans, Dan A. Dixon. Effect of XPO1 inhibition on colorectal cancer tumorigenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2086.

Rapid and high-purity differentiation of human medium spiny neurons reveals LMNB1 hypofunction and subtype necessity in modeling Huntington’s disease

BackgroundDifferent neural subtypes are selectively lost in diverse neurodegenerative diseases. Huntington’s disease (HD) is an inherited neurodegenerative disease characterized by motor abnormalities that primarily affect the striatum. The Huntingtin (HTT) mutation involves an expanded CAG repeat, leading to insoluble polyQ, which renders GABA+ medium spiny neurons (MSN) more venerable to cell death. Human pluripotent stem cells (hPSCs) technology allows for the construction of disease-specific models, providing valuable cellular models for studying pathogenesis, drug screening, and high-throughput analysis.MethodsIn this study, we established a method that allows for rapid and efficient generation of MSNs (> 90%) within 21 days from hPSC-derived neural progenitor cells, by introducing a specific combination of transcription factors.ResultsWe efficiently induced several neural subtypes, in parallel, based on the same cell source, and revealed that, compared to other neural subtypes, MSNs exhibited higher polyQ aggregation propensity and overexpression toxicity, more severe dysfunction in BDNF/TrkB signaling, greater susceptibility to BDNF withdrawal, and more severe disturbances in nucleocytoplasmic transport (NCT). We further found that the nuclear lamina protein LMNB1 was greatly reduced in HD neurons and mislocalized to the cytoplasm and axons. Knockdown of HTT or treatment with KPT335, an orally selective inhibitor of nuclear export (SINE), effectively attenuated the pathological phenotypes and alleviated neuronal death caused by BDNF withdrawal.ConclusionsThis study thus establishes an effective method for obtaining MSNs and underscores the necessity of using high-purity MSNs to study HD pathogenesis, especially the MSN-selective vulnerability.

Natural killer cells affect the natural course, drug resistance, and prognosis of multiple myeloma.

Multiple myeloma (MM), a stage-developed plasma cell malignancy, evolves from monoclonal gammopathy of undetermined significance (MGUS) or smoldering MM (SMM). Emerging therapies including immunomodulatory drugs, proteasome inhibitors, monoclonal antibodies, chimeric antigen-T/natural killer (NK) cells, bispecific T-cell engagers, selective inhibitors of nuclear export, and small-molecule targeted therapy have considerably improved patient survival. However, MM remains incurable owing to inevitable drug resistance and post-relapse rapid progression. NK cells with germline-encoded receptors are involved in the natural evolution of MGUS/SMM to active MM. NK cells actively recognize aberrant plasma cells undergoing malignant transformation but are yet to proliferate during the elimination phase, a process that has not been revealed in the immune editing theory. They are potential effector cells that have been neglected in the therapeutic process. Herein, we characterized changes in NK cells regarding disease evolution and elucidated its role in the early clinical monitoring of MM. Additionally, we systematically explored dynamic changes in NK cells from treated patients who are in remission or relapse to explore future combination therapy strategies to overcome drug resistance.

Major clinical research advances in gynecologic cancer in 2023: a tumultuous year for endometrial cancer.

In the 2023 series, we summarized the major clinical research advances in gynecologic oncology based on communications at the conference of Asian Society of Gynecologic Oncology Review Course. The review consisted of 1) Endometrial cancer: immune checkpoint inhibitor, antibody drug conjugates (ADCs), selective inhibitor of nuclear export, CDK4/6 inhibitors WEE1 inhibitor, poly (ADP-ribose) polymerase (PARP) inhibitors. 2) Cervical cancer: surgery in low-risk early-stage cervical cancer, therapy for locally advanced stage and advanced, metastatic, or recurrent setting; and 3) Ovarian cancer: immunotherapy, triplet therapies using immune checkpoint inhibitors along with antiangiogenic agents and PARP inhibitors, and ADCs. In 2023, the field of endometrial cancer treatment witnessed a landmark year, marked by several practice-changing outcomes with immune checkpoint inhibitors and the reliable efficacy of PARP inhibitors and ADCs.

Abstract B147: Preclinical evaluation of XPO1 inhibition with topoisomerase-I (topo-I) inhibition in colorectal cancer (CRC) cell lines and patient-derived xenograft (PDX) models

Abstract Background: Resistance to topo-I inhibitors is of significant importance in treating patients with metastatic CRC (mCRC). Selinexor and eltanexor are selective inhibitors of nuclear export, by binding to exportin 1 (XPO1, the primary nucleic export receptor, and is overexpressed in CRC). Eltanexor is an investigational XPO1 inhibitor, with similar mechanism and potency but improved tolerability in animal models. XPO1 inhibition results in nuclear localization of tumor suppressor proteins, oncoprotein mRNAs, and topoisomerases, and decreases DNA damage repair (DDR) response. Irinotecan is a topo-I inhibitor which induces DNA damage and is commonly used in mCRC. We hypothesized that XPO1 inhibition may improve response to topo-I inhibitor in mCRC by impairing the DDR response. Methods: The synergism of XPO1 inhibition (selinexor or eltanexor) with SN38 was assessed in CRC cell lines by CellTiter-Glo 2.0 and quantitated using Bliss Additivity Model using Synergy Finder 2.0. Each condition was plated either concurrent (both drugs for 72 hours) or sequential (SN38 for 24 hours then removed, followed by XPO1 inhibitor for 48 hours). Nude mice were implanted with one microsatellite stable CRC PDX model in the flanks followed by treatment with vehicle, XPO1 inhibitor, irinotecan (15 mg/kg intraperitoneal weekly), or combination. Tumor growth was measured by specific growth rate (SGR), within an IACUC-approved protocol. Tumor tissue was collected at day 7 for molecular analysis. Tissues were lysed and protein was run on 4%-12% SDS-PAGE Gel. p21 Waf/Cip and P-Histone H2A.X were used to determine DNA damage by western blot. P-Histone H2AX (pH2AX) was evaluated by immunofluorescence using primary conjugated P-Histone H2A.X antibody and DAPI for nuclear counter stain. Slides were imaged using Olympus iX83 microscope and analysis was performed using Olympus CellSens software. Results: In CRC cell lines, concurrent combination eltanexor and SN38 did not synergistically decrease viability but increased pH2AX compared to SN38 alone (~30-fold). However, sequential SN38 followed by eltanexor synergistically decreased viability at multiple dose levels; evaluation of pH2AX is ongoing. In PDX model CRC254, eltanexor (10 mg/kg and reduced to 7.5 mg/kg on day 8 to improve tolerability, orally 5 days per week) with irinotecan decreased SGR compared to irinotecan alone (SGR=0.007 vs 0.026, respectively, p=0.0003) and compared to eltanexor alone (SGR=0.029, p <0.0001). Combination treatment increased pH2AX and increased p21 expression compared to either single-agent treatment. Similar SGR results were observed with selinexor (5 mg/kg orally twice weekly). Conclusions: XPO1 inhibition and topo-I inhibition decreased CRC tumor growth in PDX models, presumably by increasing DNA double strand breaks. Cell line data suggests sequential dosing of topo-I inhibition followed by XPO1 inhibition may be effective. This work supports continued development of this combination in mCRC. Citation Format: Robert W Lentz, Adrian Dominguez, Stacey Bagby, Cameron Binns, Alexis Leal, Sunnie Kim, Sarah Lindsey Davis, Christopher H Lieu, Wells A Messersmith, Todd M Pitts. Preclinical evaluation of XPO1 inhibition with topoisomerase-I (topo-I) inhibition in colorectal cancer (CRC) cell lines and patient-derived xenograft (PDX) models [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr B147.

KPT-8602 Induced Hematopoietic Differentiation in U2AF1 S34F Mutant Cells and Myelodysplastic Syndromes Bone Marrow Stem and Progenitor Cells

Myelodysplastic syndromes (MDS) are a group of clonal bone marrow (BM) neoplasms characterized by ineffective hematopoiesis, cytopenia's, and a high risk of progression to acute myeloid leukemia. Current standard therapies include erythropoiesis stimulating agents for lower risk disease and DNMTi for higher risk MDS; however, less than half of patients respond and even the best responses are transient and non-curative. The majority of MDS patients harbor at least one of ~40 commonly found somatic gene mutations, most of which occur in splicing factor genes such as U2AF1, which also have non-canonical roles in nuclear export. KPT-8602 (Eltanexor) is a novel selective inhibitor of nuclear export (SINE) that acts by disrupting nuclear export of cargo relevant in MDS. We hypothesized that U2AF1 S34 F mutant cells would be selectively sensitive to treatment with KPT-8602. We created immortalized murine hematopoietic progenitor cells by retroviral transduction of stimulated bone marrow (BM) cells isolated from U2AF1 WT or U2AF1 S34F mice with a HOXB8_ER vector. Estrogen drives the hematopoietic transcription factor immortalizing the cells in a progenitor state, however, upon estrogen withdrawal the cells will differentiate and eventually die. This differentiation can be driven by treatment with specific growth factors such as erythropoietin (EPO) for erythroid differentiation or granulocyte macrophage colony stimulating factor (GM-CSF) for myeloid differentiation. KPT-8602 exposure induced differentiation and increased hematopoiesis in murine cell models and primary MDS samples. U2AF1 WT and U2AF1 S34F cells were plated in medium lacking estrogen and treated with GM-CSF (10nM) or EPO (1nM) with or without KPT-8602 (10nM) for 72h, then stained with Ly6C, CD11b, Ter119, and CD71 for flow cytometry analysis. In addition, we performed colony forming capacity assays in both the murine cells and primary MDS BM stem and progenitor cells and age-comparable healthy donors, with 14 day KPT-8602 exposure. Treatment with GM-CSF significantly increased the expression of Ly6C in both U2AF1 WT and U2AF1 S34F cells (WT fold change untreated vs GMCSF =1.9, p=0.03; S34F fold change untreated vs GMCSF =2.3, p<0.01). However, addition of KPT-8602 caused significantly more Ly6C expression than GM-CSF alone in the mutant cells (WT fold change GMCSF vs combination =3.1, p=0.06; S34F fold change GMCSF vs combination =4.0, p<0.01). There were no significant changes in CD11b expression with KPT-8602 treatment. We did not find a statistically significant increase in erythroid markers assessed by Ter-119 and CD71 after EPO treatment, however, KPT-8602 treatment alone showed a trend of increased expression of Ter-119 and CD71 in the mutant cells that fell just below statistical significance (Ter119 p=0.08 for WT, p=0.09 for S34F; CD71 p=0.21 for WT, p=0.06 for S34F). Additionally, we looked at selective toxicity of U2AF1 S34Fby WST-1 reagent and found no differences in toxicity between the WT or mutant cells with KPT-8602. However, U2AF1 WT and U2AF1 S34F progenitor cells showed an increase in colony forming capacity (n=1 with technical duplicates) when plated in the presence of KPT-8602 showing an average fold change in colony growth of 1.4 for U2AF1 WT and 1.3 for U2AF1 S34F underscoring the ability of KPT-8602 to induce differentiation. To confirm these results were not cell line artifacts, we next treated primary BM stem and progenitor cells from MDS patients (n=2) and healthy donors (n=4). MDS patient 1 (age 73y) was diagnosed with MDS-MLD-EB1 and harbored mutations in TP53, ASXL1, BCOR, TET2 and PPM1D. MDS patient 2 (age 79y) was diagnosed with MDS/MPN and harbored an SF3B1 mutation. Healthy donors (n=4) were all male and had a median age of 65y. Treatment with KPT-8602 (10nM) significantly increased burst and colony forming unit-erythroid (BFU-E/CFU-E) in MDS primary cells (p=0.02) with no significant increase in the healthy donors (p=0.57) (BFU-E/CFU-E fold increase was 1.1 for healthy donors and 3.5 for MDS). Collectively, these findings suggest that KPT-8602 promotes myeloid and erythroid differentiation and further validates the use of KPT-8602 as a therapeutic strategy for MDS. Future studies will fully elucidate the specific mechanisms by which KPT-8602 acts in the context of splicing factor mutations, and other commonly found MDS mutation types.

Selinexor Combined Bortezomib, Lenalidomide, and Dexamethasone for Newly Diagnosed Multiple Myeloma with Extramedullary Disease(EMD) or High-Risk Cytogenetics

BACKGROUND: High-risk(HR) cytogenetics are significantly enriched in MM with EMD , and studies consistently showed EMD and HR cytogenetics were associated with poor outcome. To date, there is no established approach for treatment of newly diagnosed multiple myeloma (NDMM) with EMD. Selinexor is a first-in-class Selective Inhibitor of Nuclear Export (SINE) compound that selectively binds and inactivates XPO1, which leads to accumulation of tumor suppressor proteins in the nucleus and re-activation of cell cycle regulators such as p53, FOXO, IkB. Meanwhile, by forcing the nuclear retention of the eIF4E protein, Selinexor reduces the cytoplasmic ribosomal translation of oncoproteins, including c-Myc, Bcl-2 and Bcl-6. In the STORM study(NCT02343042), 122 patients(pts) with penta-exposed, triple-class refractory multiple myeloma were enrolled to receive Selinexor combined with low-dose dexamethasone. 27 patients were diagnosed with EMD at baseline. The median age of patients was 64 years, the median prior therapies were 7, and 8 pts had high risk cytogenetics. Follow-up evaluation of plasma cell tumor was performed in 16 cases, and complete disappearance or shrinkage of extramedullary lesions was observed in 9 cases. It indicates that Selinexor has clinical activity in the treatment of plasma cell tumor or EMD. The treatment of MM with EMD or HR cytogenetics still faces great challenges, because there is no uniform guideline and consensus to recommend standard protocols, and prospective clinical studies are urgently needed to explore new treatment strategies. METHODS: Eligible pts were aged≥18 years of NDMM with EMD or HR cytogenetics, and an Eastern Cooperative Oncology Group(ECOG) performance status of 0-2. For induction/consolidation(21-day cycles), pts received 8 cycles of SVRd (Selinexor 60 mg PO weekly, Bortezomib 1.3 mg/m2 SC days1, 4, 8, 11, Lenalidomide 25 mg PO days 1-14, and Dexamethasone 40 mg PO weekly. In maintenance (28-day cycles), pts received SR (Selinexor+ Lenalidomide) at least 2 years until disease progression, death or withdrawal. The primary endpoint was overall response rates (ORR) by end of induction. The secondary endpoints are complete response (CR), duration of response (DOR), progression free survival (PFS), overall survival (OS) and toxicity. This trial is registered with Chinese Clinical Trial Registry, number ChiCTR2200062860. RESULTS: 8 pts with previously untreated NDMM were included from August 2022 to July 2023 in 3 hospitals. Median age was 62 (range 55-81). R-ISS stage 3 was present in 2 (25%) pts(Table 1). Based on inclusion criteria, 7 pts had EMD and 1 patient had HR cytogenetic, including 17p deletion (n=2, 25%), 1q21 gain(n=2, 25%). According to IMWG criteria, the ORR of 8 pts with NDMM was 100%, including 2 stringent complete response(sCR), 3 CR, 2 very good partial response (VGPR) and 1 partial response (PR). 1 patient evaluated with sCR at the end of the induction period was evaluated with MRD negativity after autologous stem cell transplantation (ASCT). Median time to first response in patients with a partial response or better was 1 months (1-2). This result established that SVRd regimen has a prospective response for MM with EMD or HR cytogenetic. The most common grade 3-4 treatment-emergent adverse events (occurring in ≥10% of pts) were thrombocytopenia. The most common treatment-related adverse events were grade 1 or 2, including nausea (25%), fatigue (25%), and anorexia (25%). Overall, the severe toxicities are manageable. CONCLUSIONS: SVRd as induction prior ASCT is safe and allows deep responses in NDMM patients with EMD or HR cytogenetic profile. It is worthy of further study based on the preliminary efficacy results. Longer-term results still require more pts have been enrolled and further follow-up.

The Clinical Menin Inhibitor Ziftomenib and the Nuclear Export Inhibitor Selinexor Synergistically Inhibit the Growth of MLL-r AML

CONCLUSION Menin is a scaffold protein that interacts with oncogenic histone-lysine-N-methyltransferase MLL1 (KMT2A)-fusion protein (FP) complex in MLL-rearranged ( MLL-r) AML. Menin inhibitors that evict menin from this interaction have been shown to be active against MLL-r and NPM1MT leukemia by modulating the expression of the leukemogenic homeobox A9 ( HOXA9) gene and its co-factor, MEIS1. Recent evidence showed that menin inhibitors can activate a tumor-suppressive network via a non-canonical transcriptional program through UTX. On the other hand, selective inhibitor of nuclear export (SINE) against XPO1/CRM1 has been shown to have robust anti-leukemia activity via enrichment of tumor suppressor proteins in the nucleus. In the present study, we hypothesized that menin and nuclear export inhibition would synergistically suppress AML cell proliferation and possibly sensitize menin inhibitor-resistant cells. We have used the clinical-stage menin inhibitor ziftomenib and SINE compound selinexor to simultaneously target menin-KMT2A protein-protein interactions and nuclear export. To assess growth inhibition, an ATP-based cell proliferation assay was used. Combination synergy was determined using CalcuSyn Version 2.0 synergy software. Stem-like progenitor cells were isolated using the StemSpan CD34+ expansion kit (StemCell Tech). Colony formation efficiency was determined using a Methocult assay (StemCell Tech). Gene and protein expression was detected using quantitative real-time PCR and western blotting. Flow cytometric analysis was performed to detect cell death and cell cycle status. We have performed the whole transcriptomic analysis via the RNA sequencing approach. The clinical candidate drug ziftomenib, in combination with selinexor, synergistically inhibited the growth of MLL-r AML cell lines (MV4;11 and MOLM13) (CI<1) [Fig.1A]. The combination of menin and XPO1 inhibitors significantly suppressed colony formation of CD34+ MLL-r progenitor stem cells derived from primary patient samples but was not toxic to normal CD34+ human hematopoietic progenitor stem cells (HPSCs). Menin inhibitor treatment caused the downregulation of menin protein along with its downstream targets HOXA9, MEIS1, and FLT3 in western blot analysis. Interestingly, selinexor also reduced menin, HOXA9, and MEIS1 protein levels. The combination enhanced menin down-expression, suggesting a molecular basis for the synergy between the two compounds. Ziftomenib suppressed the expression of menin in a time-dependent manner, which is evident as early as six hours of treatment. The combination showed increased CD11b, a marker of monocytic differentiation in MV4-11 treated cells. The combination also significantly enhanced both early and late apoptotic cell death in MLL-rearranged AML cells compared to either compound alone. Compared to controls, ziftomenib and selinexor-treated samples individually showed increased apoptotic and decreased G2/M populations, significantly enhanced in the combination. We observed differential expression of certain mRNAs and micro RNAs (miRs) in MV4-11 treated cells. The TMEM191B, SH3TC1, and SULT1C2 mRNAs were upregulated by ziftomenib and selinexor, which are enhanced further in the combination group. On the contrary, CENPK, CKS2, KIF18A, and H2BC4 mRNAs were downregulated by a single agent or combination. Among miRs, hsa-miR-34a-5p, hsa-miR-142-3p, hsa-miR-26b-5p were upregulated, and hsa-miR-33b-3p, hsa-miR-4454, hsa-miR-210-3p and hsa-miR-130b-3p [reported to be an essential lineage-specific codriver of MLL-AF4 leukemia] were downregulated by single agent or combination. Such mRNAs and miRs panels could serve as biomarkers for treatment response. MV4-11 cell line-derived xenografts in NSG mice showed a significant difference in survival in the combination arm compared to any single agent. Metronomic dosing also showed robust improvement in survival in the combination arm. Patient-derived xenografted NSG mice model using human primary MLLr re-transplantable leukemia cells showed improved survival in the combination arm [Fig. 1B]. These preclinical findings demonstrate that simultaneous inhibition of the menin-KMT2A interaction and nuclear export is a viable strategy for the treatment of MLL-r AML. Ongoing experiments with functional proteomic analysis will be presented at the ASH meeting.

Update of Swatch Study: Selinxor Combined with Lenalidomide and Rituximab (R2) in Adults with Diffuse Large B Cell Lymphoma (DLBCL) and Indolent Non-Hodgkin's Lymphoma (iNHL)

Background： Patients (pts) with relapsed/refractory (R/R) DLBCL and iNHL who are ineligible for, or relapse after, high-dose chemotherapy (HDC)/autologous stem cell transplantation (ASCT) have a poor prognosis and limited treatment options. Selinexor, a selective inhibitor of nuclear export has received accelerated approval by the U.S. Food and Drug Administration, for the treatment of adult patients with R/R DLBCL. Phase I/II study (NCT05265975), selinexor in combination with lenalidomide and rituximab (R2) for R/R DLBCL and iNHL, is ongoing. Phase I results were previously reported at ICML 2023 (Weili Zhao et al., ICML 2023, #658) and the recommended phase 2 dosing (RP2D) was determined. Aims: Here we update the preliminary results of SWATCH study. Methods： Additional 6 subjects will be recruited at this dose level 60mg to further confirm the safety and tolerability of RP2D. Eligible pts were treated with 6 cycles of rituximab (375mg/m2 on day 1), lenalidomide (25mg on d1-10) and selinexor (dose level: 60mg, on days 1, 8,15 of each 28-day cycle), followed by selinexor and lenalidomide maintenance until disease progression. Dose limiting toxicities (DLT) was defined as the occurrence of severe toxicities during the first cycle: grade 3 febrile neutropenia> 5 days, grade 4 neutropenia or thrombocytopenia >7 days, grade 3/4 thrombocytopenia with hemorrhage, or any grade 3 non-hematologic toxicity >7 days. Results: From May 2022 to April 2023, 16 pts were enrolled and no DLT occurred. At baseline in these 16 pts, refractory to last line was 93.75% and primary refractory was 68.75%. Among 12 efficacy evaluable pts, 3 pts achieved complete response (CR), 5 pts achieved partial response (PR) and another 4 pts achieved progressive disease (PD). Most AEs were grade 1 or 2 and were reversible with supportive care or dose modification. At data cutoff (June 1, 2023), 7 pts were still receiving treatment and no pts came off study due to intolerability or AEs. Median PFS and median DOR were 11.2 months and not reached. Conclusion： Selinexor in combination with lenalidomide and rituximab showed encouraging preliminary efficacy and generally tolerable toxicity with an ORR of 66.7%, CR of 25% and median PFS 11.2 months in all evaluable dose level pts, and with an ORR of 80% and CR of 20% in evaluable selinexor 60mg dose (RP2D). This study is currently enrolling patients in the dose expansion group.

Selinexor in Combination with Salvage Regimen for Refractory Diffuse Large B-Cell Lymphoma (DLBCL) Patients with TP53 Alterations

Background TP53 has been identified as one of the most frequently altered gene in diffuse large B-cell lymphoma (DLBCL). The prognosis of DLBCL patients with TP53 mutations ( TP53mut) was poor prognosis in R-CHOP era, even with treatments like autologous stem-cell transplantation (ASCT) or anti-CD19 chimeric antigen receptor T-cell (CAR-T) therapy. Moreover, TP53 mutations are more prevalent at relapse and are associated with therapeutic resistance. Selinexor is a selective inhibitor of nuclear export with promising anti-cancer properties and preclinical studies have shown its potential to suppress tumor cells with TP53 mutations. Several clinical studies proved selinexor in combination with R-GDP/R-ICE/R-Gemox was effective in relapsed/refractory DLBCL. Method The study enrolled relapsed/refractory DLBCL patients with TP53 alterations (including TP53 mutation and/or deletion) for treatment with selinexor in combination with salvage regimens (R-GDP/R-ICE/R-Gemox) since November 2021 in our center. The treatment was administered orally as 40 mg of selinexor on days 1, 8, and 15, combined with one of the following regimens: R-GDP (R 375mg/m2 d0, gemcitabine 1g/m2*d1, cisplatin 25mg/m2 d1-d3, dexamethasone 40mg d1-d4). R-ICE (R 375mg/m2 d0, ifosfamide 1.5g/m2*3d, carboplatin (AUC 5) and etoposide 100mg/m2*3d). R-Gemox ((R 375mg/m2 d0, gemcitabine 1g/m2*d1, oxaliplatin 100mg/m2*d1) every 3 weeks as per physician's choice. Objective response rate (ORR) was evaluated every 3 cycles based on Lugano 2014 criteria and Adverse events (AE) were rated according to the NCI CTCAE 5.0. Results 20 patients were treated with selinexor plus salvage regimen in this study and received at least two cycles of treatment, making them eligible for analysis. The median age of the 20 patients was 54 years (range 15 to 77), of this patients, 12 (60%) were male, 12 (60%) patients had disease stage III-IV at screening, and 45% with IPI>2. The median number of prior regimen was 1 (range, 1-4) with 2 patients (2 L) and 1 patient (3L). ALL patients were refractory to the last line of treatment. The patients received a median of three cycles (range, 2-6) of selinexor 40mg once a week combined with salvage regimen (13 patients received selinexor plus R-GDP, 6 with selinexor plus R-ICE and 1 with selinexor plus R-Gemox). The mutational profile of patients was presented in Figure A (14 patients with TP53 mutation, 5 patients with TP53 mutation and deletion, 1 with TP53 deletion). The best overall and complete response rates were 75% and 25%, respectively. Among them, 6 patients in PR and 1 patient in SD received CART treatment, and 5 achieved PR and 2 with CR after CART treatment (Figure B). One patient experienced PD after selinexor+R-GDP and died of disease progression within one month after CART transfusion. 1 SD patient transferred to CD3/CD20 bispecific antibody clinical trial and still progressed during the bispecific treatment. Taken together, selinexor-based salvage regimen had promising response rate in refractory DLBCL with TP53 alterations, and could be a potential bridging approach before CART therapy. Patients responded to selinexor-based regimen tended to have better outcome after CART or bispecific antibody treatment. Conclusions TP53 alterations are associated with poor outcomes in DLBCL. We identified an effective dosing schedule of selinexor (40mg QW) in combination with R-GDP/R-ICE/R-Gemox for TP53-altered refractory DLBCL patients. Further research is warranted to investigate the mechanism of action behind this treatment approach

Phase 2 Search Study：XPO1 Inhibitor (ATG-010) Monotherapy in Heavily Pretreated Chinese Patients with Relapsed or Refractory Diffuse Large B-Cell Lymphoma

Background Relapsed or refractory diffuse large B-cell lymphoma (R/R DLBCL) is an aggressive and most globally prevalent subtype of non-Hodgkin's lymphoma with a dismal prognosis. Selinexor (ATG-010) is an oral selective inhibitor of nuclear export, which blocks exportin1 (XPO1). The US FDA granted accelerated approval to selinexor for the treatment of adult patients (pts) with DLBCL, not otherwise specified, including DLBCL arising from follicular lymphoma, after at least 2 lines of systemic therapy based on the Phase 2b SADAL study (NCT02227251). SEARCH is a single arm, Phase 2, registrational bridging study to assess efficacy and safety of selinexor in Chinese pts with R/R DLBCL. Method SEARCH was designed to evaluate safety and efficacy of selinexor (60mg Days 1 and 3 of Weeks 1 to 4 of each 4-week cycle) in R/R DLBCL pts in China with 2-5 prior lines of systemic therapy. The primary endpoint was overall response rate (ORR) assessed by an Independent Review Committee (IRC). The study was registered at ClinicalTrials.gov (NCT03992339), with the primary analysis results presented here. Results As of 31 st May 2023 (6 months post last pt dosed), 5 (8.3%) of the 60 treated pts remained on treatment. Median follow-up was 27.7 months (mo) (range: 6.0-37.7). Median age was 58.5 years (20.0%≥70yrs). Median duration from initial DLBCL diagnosis was 1.8 years (range: 0.5-11.2). A total of 7 pts (11.7%) had DLBCL arising from indolent lymphoma, 4 (6.7%) had creatinine clearance <60ml/min and 27 (45.0%)/33 (55.0%) had GCB/non-GCB subtype, respectively. Median number of prior regimens was 3 (range: 2-5); 5 pts (8.3%) had received prior ASCT. Patients had received the following novel treatments, which were not previously received by patients in SADAL: 10 (16.7%) chidamide, 8 (13.3%) BTK inhibitor, 6 (10.0%) PD-1/PD-L1 antibodies, 3 (5.0%) polatuzumab, 1 (1.7%) PI3K inhibitor, and 4 pts (6.7%) had undergone CAR-T cell therapy. Thirty-two pts (53.3%) were with primary refractory DLBCL and 54 pts (90.0%) were refractory to the last systemic therapy for DLBCL. ORR was 21.7% (95% CI: 12.1, 34.2) and CR rate was 16.7%. Median duration of response (DOR) was 7.6 mo, median progression free survival (PFS) was 1.9 mo, and median overall survival (OS) was 8.5 mo. Efficacy was evident in pts who had poor prognostic factors, including elderly pts (≥70yrs) with ORR 16.7%, pts with renal dysfunction with ORR 25.0%, primary refractory pts with ORR 18.8% and pts refractory to their last systemic therapy with ORR 16.7%. And pts with De novo/transformed DLBCL with ORR 17.0%/57.1%, pts with GCB/non-GCB DLBCL with ORR 25.9%/18.2%, pts with/without prior ASCT with ORR 40.0%/20.0%, pts with 2/more than 2 previous regimens with ORR 25.9%/18.2%. One pt (1/4) with prior CAR-T achieved PR assessed by investigators. All pts experienced at least one treatment-emergent adverse event (TEAE), 47 (78.3%) with at least one Grade 3/4 TEAE, and 24 (40.0%) with at least one serious TEAE. The most common non-hematologic TEAE of any grade (≥20%) included decreased appetite (61.7%), nausea (58.3%), weight loss (38.3%), vomiting (33.3%), diarrhea (31.7%), asthenia (30.0%), hyponatremia (26.7%), constipation (25.0%) and AST increased (20.0%). The most common grade≥3 non-hematologic TEAE (≥2%) were decreased appetite (6.7%), diarrhea (5.0%), vomiting (5.0%), hyponatremia (3.3%), asthenia (3.3%), pneumonia (3.3%), dyspnea (3.3%) and COVID-19 pneumonia (3.3%). The most common hematologic TEAE of any grade (≥20%) were thrombocytopenia (83.3%), leukopenia (81.7%), neutropenia (80.0%), anemia (75.0%) and lymphopenia (30.0%). The most common grade≥3 hematologic TEAE (≥10%) were thrombocytopenia (41.7%), leukopenia (40.0%), neutropenia (36.7%), anemia (23.3%) and lymphopenia (16.7%). The most common AEs were generally manageable by dose modification and supportive care. Conclusions R/R DLBCL remains a high unmet medical need, especially in pts who are ineligible/frail to transplantation. The SEARCH study demonstrates clinically meaningful ORR in Chinese R/R DLBCL pts treated with selinexor monotherapy, consistent with the global study. Adverse events were generally manageable with appropriate supportive care and dose modification. These data are generally consistent with the SADAL study and supports the use of selinexor as an oral, chemotherapy-free treatment option for R/R DLBCL patients in China.

Selinexor Disrupts Epigenetic Programing and Modulates Immunogenicity in Multiple Myeloma

Introduction: Multiple myeloma (MM), remains an incurable, but treatable, malignancy that has benefitted from the integration of novel immunologic agents in clinical use, such as monoclonal antibody, bispecific T cell engager (TCE) and chimeric antigen receptor T (CAR-T) cell and antibody-drug conjugate based therapies. While these agents have shown great promise in treating relapsed/refractory MM patients, there is heterogeneity in response to therapy due to differences in patients' immune tumor microenvironments (iTME) and immunogenicity of the tumor cells. Previously (Sudalagunta et. al., ASH 2021), we used functional genomic screening of 53 MM samples to characterize the transcriptomic profile associated with sensitivity to the selective nuclear export inhibitor, selinexor (SELI), which was shown to be inversely correlated with the transcriptomic profile associated with sensitivity to an anti-CD38 monoclonal antibody in 106 MM samples. In this study, we investigate the cellular mechanisms of SELI resistance leading to an immunogenic cell state. Methods: Primary cells from an additional set of MM patients (n=65) were used for paired bulk RNAseq and an organotypic ex vivo drug sensitivity assay. Cellular viability was assessed using digital analysis of brightfield longitudinal images, and drug sensitivity was assessed as area under the dose-time-response curve (AUC) for each sample. We conducted gene set enrichment analysis (GSEA) on paired RNAseq data and ex vivo AUC of SELI. Individual genes and their respective correlations with ex vivo AUC of SELI were ranked from highest to lowest. We used RNAseq to examine the role of acute exposure to SELI on CD138-selected cells from paired pre/post treatment bone marrow specimens of five MM patients enrolled in the NCT02186834 clinical trial, taken prior to treatment with SELI and dexamethasone (DEX) and one/two weeks post-induction. Paired t-tests were carried out to quantify the changes. Results: In our previous analysis of 844 MM samples, a subset of the genes whose expression is positively correlated with SELI AUC are controlled by H3K27me3, which is catalyzed by nuclear accumulation of EZH2. Tripathi et. al. (AACR Annual Meeting 2022 & 2023) have demonstrated that XPO1 and EZH2 form a complex, and inhibition of XPO1 activity blocks export of EZH2. GSEA of a new cohort of 65 MM patient samples demonstrated increased ex vivo SELI sensitivity (lower AUC, hence negative correlation) in samples with higher expression of known epigenetic regulators of the polycomb repressive complex 2 (PRC2), such as EZH2, SUZ12, and EED; as shown in Figure a, which led to lowering of expression of genes bound by these proteins due to gene silencing via H3K27me3, shown in red in Figure a, according to GSEA of ChIPseq databases. Furthermore, gene expression profiles of paired pre/post SELI/DEX treatment samples showed reduced expression of genes associated with H3K27me3 histone modification (paired t-test p=2.06e-83, 1.1061e-81, 2.56e-80, 5.15e-12, 6.22e-4) in all five patients. These observations suggest that XPO1 inhibition leads to nuclear accumulation of epigenetic modulators like EZH2, SUZ12, and EED, which catalyze H3K27me3 activity leading to silencing of H3K27me3-regulated genes. GSEA of paired ex vivo AUC and RNAseq data for an EZH2 inhibitor (EPZ-6438) resulted in negative correlation between expression of genes in PRC2 and ex vivo sensitivity, similar to SELI. Interestingly, we observed that this epigenetic mechanism of resistance to SELI is inversely associated with key immunological targets in MM such as CD74, SLAMF7, CD38, CD46, TNFRSF13B, and LY9 as shown in Figure a. In Figure b, we present a graphical visualization of intracellular changes due to exposure to SELI in a naïve and a SELI-resistant MM cell. Conclusions: Here we propose that SELI disrupts EZH2 subcellular localization, dysregulating H3K27me3-gene suppression. Sequential BM biopsies from SELI treated patients demonstrate decreased expression of H3K27me3-regulated genes, suggesting increased EZH2 activity by nuclear accumulation. Finally, SELI-resistant primary cells have increased expression of EZH2 regulated immunotherapy target genes (e.g. CD38, SLAMF7), suggesting a possible therapeutic strategy of sequential treatment of SELI followed by immunotherapy. Using multiparameter flow cytometry of samples pre/post SELI/DEX induction, we will study SELI's effect on iTME.

Combining Selinexor with R-CHOP in the Treatment of Newly Diagnosed High-Risk (IPI 3-5) GCB Subtype DLBCL Patients: A Multicenter, Open Label Phase 2 Study

Background Diffuse large B-cell lymphoma (DLBCL) is an aggressive and highly heterogeneous lymphoma, and for high-risk group who has an International Prognostic Index (IPI) score of 3-5 it is more difficult to treat (Teras LR,2016; Ziepert M,2010). Under the standard R-CHOP-like immunochemotherapy, the 3-year overall survival (OS) rate of patients with IPI score of 0-1, 2, 3, 4-5 were 91%, 81%, 65% and 59%, respectively (Ziepert M,2010). The efficacy for high-risk population (IPI 3-5) was limited even after intensive chemotherapy, with an ORR of 74.5% and CR of 47.3% under R-CODOX-M/R-IVAC (McMillan AK,2020). Nonetheless, adding new agents to R-CHOP shows better efficacy in patients with IPI 3-5(Tilly H,2022; Nowakowski GS,2021). GCB subtype has better prognosis, but 20% of patients still relapsed after R-CHOP therapy (Nowakowski GS,2015), and no more benefit was achieved by modifying regimen with new agents like polatuzumab-R-CHP (Tilly H,2022), adding on lenalidomide (Nowakowski GS,2015) or ibrutinib (Wilson WH,2021). Selinexor is the only approved oral selective nuclear export inhibitor which demonstrated a 34% ORR in GCB subgroup as a monotherapy in relapsed/refractory DLBCL (Kalakonda N,2020). Selinexor combined with R-CHOP showed a CR rate of 58.8% and ORR of 94.1% in 17 high risk GCB DLBCL patients in a real-world setting (Zhiming Li,2023). This phase 2 study (NCT05422066) further explored the benefit and safety of Selinexor plus R-CHOP in the treatment of newly diagnosed (ND) GCB DLBCL patients with IPI 3-5. Methods This is a multicenter, open label, single arm phase 2 study enrolled 18~75 years old ND GCB DLBCL patients with IPI 3-5. Patients were administered selinexor 60mg QW in combination with standard R-CHOP therapy for 6 cycles (Rituximab 375 mg/m 2, cyclophosphamide 750 mg/m 2, doxorubicin 50 mg/m 2 IV, vincristine 0.5 mg/kg on day 1, prednisone 100 mg PO on days 1-5 in a 21-day cycle). The primary endpoint is complete remission (CR) rate. Secondary endpoints include objective response Rate (ORR), progression free survival (PFS), disease free survival (DFS), overall survival (OS), safety and tolerability. Results The median age of 15 patients was 59 years (range 25-71), with 10 males (66.7%). All patients were in advanced stage according to Ann Arbor staging system, with 13 patients in stage IV, and 2 in stage III. 11(73.3%) patients had ≥2 extranodal lesions and 9 (60%) patients had higher LDH level at baseline. 1 patient had TP53 mutation, and 6 patients (40%) had double expressor lymphoma (DEL) (Table 1). The overall best ORR and CR were 100% and 60%, respectively. The CR rate in 6 DEL patients were 50%; Patients with ≥2 extranodal lesions reached a CR of 54.5% (n=11), while 3 out of 4 patients with≤1 extranodal lesions completely responded. The CR rates of patients with Ki-67≥80% vs＜80% were 50% vs 62.5%, respectively. Median PFS and OS were not reached yet with a median follow-up of 8 months (range 2-11 months). 2 patients had progressive disease with 1 progressed after C4 and the other 1 after C6. 4 patients with viral hepatitis (3 HBV, 1 HCV) were administered both anti-tumor and antiviral therapy, and their HBV-DNA and HCV-RNA levels continuously declined (till undetectable) along with their tumor load (3 CR ,1 PR). Common treatment-relate adverse events (grade 3/4, all grades) included: leukopenia (80%, 93%), neutropenia (73%, 87%), anemia (27%, 93%), thrombocytopenia (27%, 67%), lymphopenia (20%, 27%), anorexia (13%, 40%), pneumonia (13%,40%), hypertriglyceridemia (7%, 40%), diarrhea (7%, 20%). All AEs were managed with appropriate supportive care and dose adjustments. 8 out of 15 patients had a dose reduction of selinexor to 40mg (initial dose 60mg QW) due to AE, 3 in C2 and the other 5 in C4-C5. All patients were continuously treated after dose reduction, and no treatment-related deaths occurred. Overall, 6 patients completed 6 cycles of selinexor+R-CHOP treatment with sustained remission, and 6 patients were still receiving therapy at time of writing this abstract (4 in C6, 2 in C3). 3 patients ended study, 2 PD and 1 withdrew informed consent after PR at the end of C4 (Figure 1). Conclusion Once weekly 60mg selinexor can be safely combined with R-CHOP in ND high risk (IPI 3-5) GCB subtype DLBCL patients with ORR of 100% and CR of 60%. No viral reactivation was observed in patients with viral hepatitis with simultaneous antiviral therapy.

RNA-binding protein hnRNPU regulates multiple myeloma resistance to selinexor

Multiple myeloma (MM) is an incurable haematological cancer. Selinexor is the first-in-class selective inhibitor of nuclear export (SINE) and was newly approved for the treatment of MM. Until now, very few studies have investigated selinexor resistance in MM. Heterogeneous nuclear ribonucleoprotein U (hnRNPU) is an RNA-binding protein and a component of hnRNP complexes. Here we found that hnRNPU regulates MM sensitivity to selinexor. Cell apoptosis assays were performed to compare selinexor-induced cell death in control knockdown (CTR-KD) and hnRNPU knockdown (hnR-KD) MM cells. HnRNPU knockdown-induced nuclear protein retention was examined by proteomics array. HnRNPU-conferred mRNA translation regulation was evaluated by sucrose gradient assay, RNA electrophoresis mobility shift assay, and RNA pull-down assay. We found that hnR-KD MM cells were more sensitive to selinexor-induced cell death in vitro and in mouse model. MM patients who responded to selinexor had relatively low hnRNPU expression. In brief, hnRNPU comprehensively regulated MM sensitivity to selinexor by affecting the localization of LTV1 and NMD3, and mRNA translation of MDM2 and RAN, which were involved in XPO1-mediated nuclear export of ribosome subunits and tumor suppressors. Our discoveries indicate that hnRNPU might be a possible marker to categorize MM patients for the use of Selinexor.

Sequential Administration of Selinexor and CAR-T Therapy in Relapsed/ Refractory Multiple Myeloma

Introduction: Selinexor is a novel, oral selective inhibitor of nuclear export (SINE) that binds to exportin 1 and exhibits anti-tumor activity by impairing nuclear export of proteins including oncogenes and tumor suppressor proteins and is approved for use in patients with relapsed refractory multiple myeloma(RRMM). Anti-BCMA directed CAR-T therapy for patients with relapsed/refractory multiple myeloma (RRMM) is a promising new class of therapy, which has shown a high level of efficacy. Sequential administration of selinexor followed by CD19 CAR-T has shown enhanced efficacy in human phase II trials and animal models of human non-hodgkin lymphoma(Stadel et al., 2022). In this retrospective single institutional study, we report outcomes of patients with RRMM who were treated with Selinexor based regimen prior to apheresis for CAR-T therapy. Methods: We conducted a retrospective study on an IRB-approved protocol for all patients who were treated with Selinexor based regimen immediately prior to apheresis as a prior line of therapy at Hackensack University Medical Center between June 2015 and July 2022. Demographic characteristics, molecular studies, treatment and response information were recorded and included in the study. Response to CAR-T was assessed by the treating physician per International Myeloma Working Group (IMWG) criteria. Survival analysis was performed using the Kaplan-Meier method including PFS and Overall survival (OS). Results: Between September 9, 2021, and April 3, 2023, 7 patients received CAR-T who were treated with Selinexor immediately prior to apheresis. The median age was 65.7 years (range: 55.1-77.1 years). Patients had a median of 6 (range: 4-10) lines of therapy (LOT) prior to CAR-T. 5 out of the 7 patients had double hit myeloma (all 5 with 17p and one other high risk). Four patients were treated with selinexor, carfilzomib and dexamethasone; two patients were treated with selinexor, daratumumab and dexamethasone and one patient was treated with selinexor, pomalidomide and dexamethasone. Four patients received Idecabtagene vicleucel (ide-cel) and three patients received ciltacabtagene autoleucel (cilta-cel). ORR was 100% with all 7 pts achieving very good partial response or better (>=VGPR). 2 patients had bone marrow biopsies that confirmed MRD -ve sCR in both patients. None of the patients have progressed so far, although median follow-up is short at 5.6 months. All patients had hematologic toxicities, 4/7 with grade III anemia (57.1%), 3/7 (42.8%) with grade or higher thrombocytopenia and 4/7 (57.1%) had grade 3 neutropenia. 2 of 7 patients had prolonged cytopenia for >6 months because of pre-existing underlying diagnoses of CCUS and MDS. 5 out of 7 patients had grade 1 Cytokine release syndrome (CRS). The other two patients did not experience CRS. Time of CRS onset was variable 2-10 days. No ICANS or infectious complications were observed. Conclusions: These results suggest that sequential use of Selinexor and CART in high risk RRMM may be an effective treatment strategy to provide deep and durable responses. The findings of our study are promising although it is limited by a small sample size and short follow-up. Further investigation in a larger study and longer follow up would be important to confirm our findings.