Purpose: Selinexor is an oral selective inhibitor of exportin-1 (XPO1) with efficacy in various solid and hematologic tumors. We assessed intratumoral penetration, safety, and efficacy of selinexor monotherapy for recurrent glioblastoma. Patients and Methods: Seventy-six adults with Karnofsky Performance Status ≥ 60 were enrolled. Patients undergoing cytoreductive surgery received up to three selinexor doses (twice weekly) preoperatively (Arm A; n = 8 patients). Patients not undergoing surgery received 50 mg/m2 (Arm B, n = 24), or 60 mg (Arm C, n = 14) twice weekly, or 80 mg once weekly (Arm D; n = 30). Primary endpoint was 6-month progression-free survival rate (PFS6). Results: Median selinexor concentrations in resected tumors from patients receiving presurgical selinexor was 105.4 nmol/L (range 39.7–291 nmol/L). In Arms B, C, and D, respectively, the PFS6 was 10% [95% confidence interval (CI), 2.79–35.9], 7.7% (95% CI, 1.17–50.6), and 17% (95% CI, 7.78–38.3). Measurable reduction in tumor size was observed in 19 (28%) and RANO-response rate overall was 8.8% [Arm B, 8.3% (95% CI, 1.0–27.0); C: 7.7% (95% CI, 0.2–36.0); D: 10% (95% CI, 2.1–26.5)], with one complete and two durable partial responses in Arm D. Serious adverse events (AEs) occurred in 26 (34%) patients; 1 (1.3%) was fatal. The most common treatment-related AEs were fatigue (61%), nausea (59%), decreased appetite (43%), and thrombocytopenia (43%), and were manageable by supportive care and dose modification. Molecular studies identified a signature predictive of response (AUC = 0.88). Conclusions: At 80 mg weekly, single-agent selinexor induced responses and clinically relevant PFS6 with manageable side effects requiring dose reductions. Ongoing trials are evaluating safety and efficacy of selinexor in combination with other therapies for newly diagnosed or recurrent glioblastoma.
Background: Colorectal cancer (CRC) is the second leading cause of cancer related death. In approximately half of all CRC cases, oncogenic KRAS mutations underlie poor prognosis and drug resistance. A previous multi-genomic analysis of 4,725 biological processes with 106 human non-small-cell lung cancer cells identified nuclear transport machinery as the sole process selectively required for the survival of KRAS mutant cells. Selinexor is a clinically approved oral inhibitor of nuclear export protein Exportin 1 (XPO1/CRM1). In preclinical studies, selinexor demonstrated robust synthetical lethality with native or engineered oncogenic KRAS both in vitro and in vivo. Clinical activity of selinexor monotherapy was observed in CRC patients with various KRAS oncogenic mutations (Razak 2016 JCO). We performed preclinical studies to evaluate the effectiveness of selinexor and the anti-PD-1 antibody RMP1-14 in syngeneic mouse models of KRAS mutant CRC. Methods: Two syngeneic CT-26 KRAS mutant CRC mouse models were tested: 1) metastasis model with intra-hepatically injected CT-26 cells expressing luciferase (8 mice per group); and 2) subcutaneous model with CT-26 injected into the left flank (10 mice per group). Mice were allocated to four groups: vehicle control, selinexor (15 mg/kg, PO, once weekly), RMP1-14 (300 µg/mouse, IP, once weekly), or the combination of selinexor and RMP1-14. Tumor progression and body weight of test mice were monitored throughout the experiment. Tumor samples and plasma were collected at the end of the study for further analysis. Results: Both selinexor and RMP1-14 demonstrated single agent activity against KRAS mutant CRC in the two mouse models relative to controls. In the metastasis model, tumor growth inhibition (TGI) at Day 21 was 63.5% (p=0.0001) for selinexor and 68.9% (p<0.0001) for RMP1-14. The combination of selinexor and RMP1-14 significantly inhibited tumor growth and metastasis with a TGI of 98.9% (p<0.0001). No tumors were detected in two mice from the combination group at the end of the study. A similar trend was observed in the subcutaneous xenograft models, at Day 17, TGIs for selinexor, RMP1-14 and combination treatment were 17.6% (p=0.0921), 26.9% (p=0.0059) and 70.4% (p<0.0001), respectively. Conclusions: Synergistic anti-cancer activity of selinexor and anti-PD-1 antibody in KRAS mutant CRC mouse models warrants further clinical investigation. Citation Format: Hua Chang, Leah Henegar, Christopher J. Walker, Trinayan Kashyap, Marie Maloof, Feng Wang, Kathleen Martyn, Shira Orr, Michael G. Kauffman, Sharon Shacham, Yosef Landesman. Selinexor synergizes with anti-PD-1 antibody and inhibits tumor growth and metastasis in syngeneic mouse models of KRAS mutant colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5519.
Chordoma is a rare cancer that grows in the base of the skull and along the mobile spine from remnants of embryonic notochord tissue. The cornerstone of current treatments is surgical excision with adjuvant radiation therapy, although complete surgical removal is not always possible. Chordomas have high rates of metastasis and recurrence, with no approved targeted agents. Selinexor and eltanexor are selective inhibitors of nuclear export (SINE) that prevent the karyopherin protein exportin-1 (XPO1) from shuttling its cargo proteins through nuclear pore complexes out of the nucleus and into the cytoplasm. As cancer cells overexpress XPO1, and many of its cargos include tumor suppressor proteins and complexes bound to oncogene mRNAs, XPO1 inhibition can suppress oncogene translation and restore tumor suppressor protein activity in different cancer types. SINE compounds have exhibited anti-cancer activity in a wide range of hematological and solid tumor malignancies. Here we demonstrate the preclinical effectiveness of SINE compounds used as single agents or in combination with either the proteasome inhibitor, bortezomib, or the CDK4/6 inhibitor, abemaciclib, against various patient- derived xenograft (PDX) mouse models of chordoma, which included clival and sacral chordomas from adult or pediatric patients with either primary or metastatic disease, with either differentiated or poorly differentiated subtypes. SINE treatment significantly impaired tumor growth in all five tested chordoma models, with the selinexor and abemaciclib combination showing the strongest activity (tumor growth inhibition of 78-92%). Immunohistochemistry analysis of excised tumors revealed that selinexor treatment resulted in marked induction of apoptosis and reduced cell proliferation, as well as nuclear accumulation of SMAD4, and reduction of Brachyury and YAP1. RNA sequencing showed selinexor treatment resulted in differences in activated and repressed signaling pathways between the PDX models, including changes in WNT signaling, E2F pathways and glucocorticoid receptor signaling. This is consistent with SINE-compound mediated XPO1 inhibition exhibiting anti-cancer activity through a broad range of different mechanisms in different molecular chordoma subsets. Our findings validate the need for further investigation into selinexor as a targeted therapeutic for chordoma, especially in combination with abemaciclib.
<div>AbstractPurpose:<p>Selinexor is an oral selective inhibitor of exportin-1 (XPO1) with efficacy in various solid and hematologic tumors. We assessed intratumoral penetration, safety, and efficacy of selinexor monotherapy for recurrent glioblastoma.</p>Patients and Methods:<p>Seventy-six adults with Karnofsky Performance Status ≥ 60 were enrolled. Patients undergoing cytoreductive surgery received up to three selinexor doses (twice weekly) preoperatively (Arm A; <i>n</i> = 8 patients). Patients not undergoing surgery received 50 mg/m<sup>2</sup> (Arm B, <i>n</i> = 24), or 60 mg (Arm C, <i>n</i> = 14) twice weekly, or 80 mg once weekly (Arm D; <i>n</i> = 30). Primary endpoint was 6-month progression-free survival rate (PFS6).</p>Results:<p>Median selinexor concentrations in resected tumors from patients receiving presurgical selinexor was 105.4 nmol/L (range 39.7–291 nmol/L). In Arms B, C, and D, respectively, the PFS6 was 10% [95% confidence interval (CI), 2.79–35.9], 7.7% (95% CI, 1.17–50.6), and 17% (95% CI, 7.78–38.3). Measurable reduction in tumor size was observed in 19 (28%) and RANO-response rate overall was 8.8% [Arm B, 8.3% (95% CI, 1.0–27.0); C: 7.7% (95% CI, 0.2–36.0); D: 10% (95% CI, 2.1–26.5)], with one complete and two durable partial responses in Arm D. Serious adverse events (AEs) occurred in 26 (34%) patients; 1 (1.3%) was fatal. The most common treatment-related AEs were fatigue (61%), nausea (59%), decreased appetite (43%), and thrombocytopenia (43%), and were manageable by supportive care and dose modification. Molecular studies identified a signature predictive of response (AUC = 0.88).</p>Conclusions:<p>At 80 mg weekly, single-agent selinexor induced responses and clinically relevant PFS6 with manageable side effects requiring dose reductions. Ongoing trials are evaluating safety and efficacy of selinexor in combination with other therapies for newly diagnosed or recurrent glioblastoma.</p></div>
The nuclear export protein exportin 1 (XPO1) is overexpressed in many cancers, including GBM. Selinexor is an inhibitor of XPO1 that crosses the blood-brain-barrier and targets cancer cells by sequestering tumor suppressor proteins and oncoprotein mRNAs in the nucleus, inducing cancer cell apoptosis. We previously reported encouraging results from a phase II trial of selinexor for molecularly unselected patients with recurrent GBM (ASCO 2019). Pre-treatment tumors from 57 patients were exome and RNA sequenced to explore molecular correlates of response, in a hypothesis generating, post-hoc, exploratory analysis. We compared overall survival (OS) and progression-free survival (PFS) between mutated and wild-type patients. Two mutated genes were associated with longer survival in selinexor treated patients: DOCK8 (n=7; PFS, P=0.013, hazard ratio [HR]=3.75 [1.32–10.62]; overall survival, P=0.009, HR=15.39 [2.00–118.34]) and PDX1 (n=5, PFS, P=0.014, HR=4.468 [1.361–14.670]). Other commonly mutated genes in glioma, including IDH1 (n=9) were observed but not associated with survival. RNAseq data were used to infer differential protein activities, which were input into a machine learning model that compared patients with selinexor sensitive disease (best response of partial or complete response, n=7) and resistant disease (best response of progressive disease, n=23). We found the inferred activities of three proteins emerged as the most associated with response and could be combined in a model to accurately predict benefit from selinexor treatment (area under the ROC curve from leave one out cross validation = 0.89 permutation test P< 0.04). The three proteins were ZC3H12A (also called MCPIP-1), a negative regulator of inflammation; RAB43, a member of the RAS family that binds GTP and regulates vesicle trafficking, and SOCS3, a suppressor of cytokine signaling that can antagonize JAK/STAT signaling. Together these data identified mutations and proteins activities for identifying patients most likely to benefit from selinexor treatment. Further studies are required for validation. ClinicalTrials.gov:NCT01986348.
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