A phase I trial of selinexor plus FLAG-Ida for the treatment of refractory/relapsed adult acute myeloid leukemia patients

XPO1 inhibition displays anti-leukemia efficacy against DNMT3A-mutant acute myeloid leukemia via downregulating glutathione pathway

Acute myeloid leukemia (AML) patients with DNA methyltransferase 3A (DNMT3A) mutation display poor prognosis, and targeted therapy is not available currently. Our previous study identified increased expression of Exportin1 (XPO1) in DNMT3AR882H AML patients. Therefore, we further investigated the therapeutic effect of XPO1 inhibition on DNMT3AR882H AML. Three types of DNMT3AR882H AML cell lines were generated, and XPO1 was significantly upregulated in all DNMT3AR882H cells compared with the wild-type (WT) cells. The XPO1 inhibitor selinexor displayed higher potential in the inhibition of proliferation, promotion of apoptosis, and blockage of the cell cycle in DNMT3AR882H cells than WT cells. Selinexor also significantly inhibited the proliferation of subcutaneous tumors in DNMT3AR882H AML model mice. Primary cells with DNMT3A mutations were more sensitive to selinexor in chemotherapy-naive AML patients. RNA sequencing of selinexor treated AML cells revealed that the majority of metabolic pathways were downregulated after selinexor treatment, with the most significant change in the glutathione metabolic pathway. Glutathione inhibitor L-Buthionine-(S, R)-sulfoximine (BSO) significantly enhanced the apoptosis-inducing effect of selinexor in DNMT3AWT/DNMT3AR882H AML cells. In conclusion, our work reveals that selinexor displays anti-leukemia efficacy against DNMT3AR882H AML via downregulating glutathione pathway. Combination of selinexor and BSO provides novel therapeutic strategy for AML treatment.

Emerging and Future Targeted Therapies for Pediatric Acute Myeloid Leukemia: Targeting the Leukemia Stem Cells

Acute myeloid leukemia (AML) is a rare subtype of acute leukemia in the pediatric and adolescent population but causes disproportionate morbidity and mortality in this age group. Standard chemotherapeutic regimens for AML have changed very little in the past 3-4 decades, but the addition of targeted agents in recent years has led to improved survival in select subsets of patients as well as a better biological understanding of the disease. Currently, one key paradigm of bench-to-bedside practice in the context of adult AML is the focus on leukemia stem cell (LSC)-targeted therapies. Here, we review current and emerging immunotherapies and other targeted agents that are in clinical use for pediatric AML through the lens of what is known (and not known) about their LSC-targeting capability. Based on a growing understanding of pediatric LSC biology, we also briefly discuss potential future agents on the horizon.

Phase 1 study of selinexor in combination with salvage chemotherapy in Adults with relapsed or refractory Acute myeloid leukemia

Selinexor, an oral inhibitor of the nuclear transport protein Exportin-1, shows promising single-agent activity in clinical trials of relapsed/refractory (R/R) acute myeloid leukemia (AML) and preclinical synergy with topoisomerase (topo) IIα inhibitors. We conducted a phase 1, dose-escalation study of selinexor with mitoxantrone, etoposide, and cytarabine (MEC) in 23 patients aged < 60 years with R/R AML. Due to dose-limiting hyponatremia in 2 patients on dose level 2 (selinexor 40 mg/m2), the maximum tolerated dose was 30 mg/m2. The most common grade ≥ 3 treatment-related non-hematologic toxicities were febrile neutropenia, catheter-related infections, diarrhea, hyponatremia, and sepsis. The overall response rate was 43% with 6 patients (26%) achieving complete remission (CR), 2 (9%) with CR with incomplete count recovery, and 2 (9%) with a morphologic leukemia-free state. Seven of 10 responders proceeded to allogeneic stem cell transplantation. The combination of selinexor with MEC is a feasibile treatment option for patients with R/R AML.

Nuclear transport proteins: structure, function, and disease relevance

Proper subcellular localization is crucial for the functioning of biomacromolecules, including proteins and RNAs. Nuclear transport is a fundamental cellular process that regulates the localization of many macromolecules within the nuclear or cytoplasmic compartments. In humans, approximately 60 proteins are involved in nuclear transport, including nucleoporins that form membrane-embedded nuclear pore complexes, karyopherins that transport cargoes through these complexes, and Ran system proteins that ensure directed and rapid transport. Many of these nuclear transport proteins play additional and essential roles in mitosis, biomolecular condensation, and gene transcription. Dysregulation of nuclear transport is linked to major human diseases such as cancer, neurodegenerative diseases, and viral infections. Selinexor (KPT-330), an inhibitor targeting the nuclear export factor XPO1 (also known as CRM1), was approved in 2019 to treat two types of blood cancers, and dozens of clinical trials of are ongoing. This review summarizes approximately three decades of research data in this field but focuses on the structure and function of individual nuclear transport proteins from recent studies, providing a cutting-edge and holistic view on the role of nuclear transport proteins in health and disease. In-depth knowledge of this rapidly evolving field has the potential to bring new insights into fundamental biology, pathogenic mechanisms, and therapeutic approaches.

Real-world experience with selinexor-containing chemotherapy-free or low-dose chemotherapy regimens for patients with relapsed/refractory acute myeloid leukemia and myeloid sarcoma

Introduction: Treatment of relapsed or refractory acute myeloid leukemia (R/R AML) and myeloid sarcoma (MS) has presented challenges for decades. Studies on selinexor in combination with various standard or intensive chemotherapy regimens for the treatment of R/R AML have demonstrated promising results. This study aimed to evaluate the efficacy and safety of chemotherapy-free or low-dose chemotherapy regimens with selinexor for R/R AML and MS patients. Methods: Ten patients with R/R AML or MS who received chemotherapy-free or low-dose chemotherapy regimens in combination with selinexor at Tongji Hospital from October 2021 to August 2022 were included in this study. The primary endpoint was overall response rate (ORR) and secondary endpoints included complete remission (CR), CR with incomplete hematological recovery (CRi), partial remission (PR), transplantation rate, and safety. Results: All patients were evaluable for response, achieving CR in four (40.0%) patients and CRi in two (20.0%) patients for a total CR/CRi of 60.0%. The ORR was 80.0% when patients with PR were included. Five (50.0%) patients underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) after treatment with selinexor-containing regimens. At the end of the follow-up, seven (70.0%) patients were alive, and three patients died of transplant-related complications or disease progression. The most frequently reported nonhematologic adverse events (AEs) in patients were grade 1 or 2 asymptomatic hyponatremia. Conclusion: The chemotherapy-free or low-dose chemotherapy regimens in combination with selinexor for R/R AML are feasible and tolerable and provide an opportunity for patients to receive transplantation.

Azacitidine Is Synergistically Lethal with XPO1 Inhibitor Selinexor in Acute Myeloid Leukemia by Targeting XPO1/eIF4E/c-MYC Signaling

Acute myeloid leukemia (AML) is a high-mortality malignancy with poor outcomes. Azacitidine induces cell death and demonstrates treatment effectiveness against AML. Selinexor (KPT-330) exhibited significant benefits in combination with typical induction treatment for AML patients. Here, we explore the antitumor effect of KPT-330 combined with AZA in AML through CCK-8, flow cytometry, RT-qPCR, western blot, and RNA-seq. Our results showed that KPT-330 combined with AZA synergistically reduced cell proliferation and induced apoptosis in AML primary cells and cell lines. Compared to the control, the KPT-330 plus AZA down-regulates the expression of XPO1, eIF4E, and c-MYC in AML. Moreover, the knockdown of c-MYC could sensitize the synergy of the combination on suppression of cell proliferation and promotion of apoptosis in AML. Moreover, the expression of XPO1 and eIF4E was elevated in AML patient cohorts, respectively. XPO1 and elF4E overexpression was associated with poor prognosis. In summary, KPT-330 with AZA exerted synergistic effects by suppressing XPO1/eIF4E/c-MYC signaling, which provided preclinical evidence for further clinical application of the novel combination in AML.

Targeting XPO1-Dependent Nuclear Export in Cancer

Nucleocytoplasmic transport of macromolecules is tightly regulated in eukaryotic cells. XPO1 is a transport factor responsible for the nuclear export of several hundred protein and RNA substrates. Elevated levels of XPO1 and recurrent mutations have been reported in multiple cancers and linked to advanced disease stage and poor survival. In recent years, several novel small-molecule inhibitors of XPO1 were developed and extensively tested in preclinical cancer models and eventually in clinical trials. In this brief review, we summarize the functions of XPO1, its role in cancer, and the latest results of clinical trials of XPO1 inhibitors.