Safety, tolerability, and clinical activity of selinexor in combination with pembrolizumab in treatment of metastatic non-small cell lung cancer

BACKGROUND

In lung cancer, overexpression of nuclear export proteins can result in inactivation of critical tumor suppressor proteins and cell-cycle regulators. Selective suppression of nuclear export proteins has immunomodulatory activities. Here, clinical safety and early efficacy data are presented on the combination of pembrolizumab and an oral selective nuclear export inhibitor, selinexor, for the treatment of metastatic non-small cell lung cancer (mNSCLC).

METHODS

The primary objective of this prospective investigator-initiated study was to determine the safety and tolerability of selinexor in combination with pembrolizumab in patients with mNSCLC. Secondary objectives included determination of objective tumor response rate, disease control rate, and progression-free survival duration.

RESULTS

A total of 17 patients were included in the final analysis. Fifteen (88%) received more than two lines of prior systemic therapy and 10 (59%) had prior exposure to anti-PD-1/programmed death-ligand 1 (PD-L1) therapy. The median age was 67.5 years. Ten patients had grade ≥3 adverse events related to selinexor treatment. Responses to treatment occurred in patients who did and did not undergo previous anti-PD-1/PD-L1 therapy and in patients with activating driver mutations. The median overall survival and progression-free survival were 11.4 months (95% CI, 3.4-19.8 months) and 3.0 months (95% CI, 1.7-5.7 months), respectively. The overall response rate was 18% and the 6-month disease control rate was 24%.

CONCLUSIONS

Selinexor in combination with pembrolizumab demonstrated promising antitumor activity in patients with mNSCLC, including those who had previously received anti-PD-1/PD-L1 therapy. The therapy-related toxic effects were consistent with the prior safety data for both drugs, and no overlapping toxic effects were observed.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02419495.

PLAIN LANGUAGE SUMMARY

New strategies to prevent or reverse resistance to immune checkpoint inhibitors are under investigation. Selective inhibitors of nuclear export proteins, such as selinexor, can induce restoration of tumor-suppressing pathways and induce potent immunomodulatory activities. This article contains the clinical safety and early efficacy data on the combination of pembrolizumab and selinexor in treatment of metastatic non-small cell lung cancer.

Ribosomal proteins as distinct "passengers" of microvesicles: new semantics in myeloma and mesenchymal stem cells' communication

Aberrant mesenchymal stem cells (MSCs) in multiple myeloma (MM) bone marrows (BM) promote disease progression and drug resistance. Here, we assayed the protein cargo transported from MM-MSCs to MM cells via microvesicles (MVs) with focus on ribosomal proteins (RPs) and assessment of their influence on translation initiation and design of MM phenotype. Proteomics analysis (mass spectrometry) demonstrated increased levels and repertoire of RPs in MM-MSCs MVs compared to normal donors (ND) counterparts (n = 3-8; P = 9.96E - 08). We limited the RPs load in MM-MSCs MVs (starvation, RSK and XPO1 inhibitions), reapplied the modified MVs to MM cell lines (U266, MM1S), and demonstrated that the RPs are essential to the proliferative effect of MM-MSCs MVs on MM cells (n = 3; P < 0.05). We also observed that inhibition with KPT-185 (XPO1 inhibitor) displayed the most extensive effect on RPs delivery into the MVs (↓80%; P = 3.12E - 05). Using flow cytometry we assessed the expression of select RPs (n = 10) in BM-MSCs cell populations (ND and MM; n ≥ 6 each). This demonstrated a heterogeneous expression of RPs in MM-MSCs with distinct subgroups, a phenomenon absent from ND-MSCs samples. These findings bring to light a new mechanism in which the tumor microenvironment participates in cancer promotion. MVs-mediated horizontal transfer of RPs between niche MSCs and myeloma cells is a systemic way to bestow pro-cancer advantages. This capacity also differentiates normal MSCs from the MM-modified MSCs and may mark their reprogramming. Future studies will be aimed at assessing the clinical and therapeutic potential of the increased RPs levels in MM-MSCs MVs.

Effects of cadmium on osteoblast cell line: Exportin 1 accumulation, p-JNK activation, DNA damage and cell apoptosis

Cadmium is an environmental metal pollutant that has been a focus of research in recent years, which is reported to cause bone disease; however, its skeletal toxicity and the mechanism involved are not yet fully known. Therefore, this study used MC3T3-E1 subclone 14 cells to determine the mechanism of cadmium toxicity on bone. Cadmium chloride (Cd) significantly reduced cell viability in a concentration-dependent manner. Exposure to Cd inhibited osteoblast-related proteins (Runx2, Col-1, STC2) and decreased alkaline phosphatase (ALP) activity. Cd caused Exportin-1 accumulation and induced DNA damage. Cd significantly down-regulated caspase 9 and induced cleaved-PARP, cleaved-caspase 3 protein level. Treatment with JNK inhibitor, SP600125, suppressed cadmium-induced elevation in the ratio of phosphorylation of JNK to JNK. Inhibition of caspase with pan-caspase inhibitor, Z-VAD-FMK, prevented MC3T3-E1 subclone 14 cells from cadmium-induced reduction of Runx2, STC2, caspase 9, and accumulation of cleaved PARP and cleaved caspase 3. Cd-induced cell survival enhanced by SP600125 but rescued by Z-VAD-FMK or KPT-335. These results suggest that cadmium cytotoxicity on bone involved exportin 1 accumulation, phosphorylation of JNK, induction of DNA damage and pro-apoptosis, which was induced by activation of caspase-dependent pathways.

Selective Inhibitors of Nuclear Export in the Treatment of Hematologic Malignancies

The correct localization of molecules between nucleus and cytoplasm is fundamental for cellular homeostasis and is controlled by a bidirectional transport system. Exportin 1 (XPO1) regulates the passage of numerous cancer-related proteins. In this review, we summarize the development of a novel class of antitumor agents, known as selective inhibitors of nuclear export (SINEs). We report results of preclinical studies and clinical trials, and discuss the mechanism of action of SINEs and their effects in multiple myeloma, non-Hodgkin lymphomas, lymphoblastic leukemia, and acute and chronic myeloid leukemia. In the future, the numerous experimental studies currently underway will allow us to define the role of SINEs and will possibly permit these substances to be introduced into daily clinical practice.