Background: The Hippo pathway (effected by the YAP/TAZ-TEAD transcriptional complex) is a major regulator of cell density and organ size, and is a major pro-growth, pro-survival pathway yet to be targeted in precision oncology. YAP/TAZ-TEAD transcription is hyperactivated by specific genetic events (e.g. YAP/TAZ oncofusions, NF2 mutations) and has been demonstrated as a key mechanism of resistance acquisition to MAPK pathway inhibition, as well as inhibition of its upstream inputs, such as EGFR and other receptor tyrosine kinases. While YAP/TAZ are globular proteins without obvious docking sites, the four TEAD family members share a highly conserved palmitoylation site suitable for inhibitor docking. Materials and Methods: We developed a virtual structural model of the palmitoylation site of TEAD and generated a series of novel inhibitors. We evaluated direct TEAD binding by Isothermal titration calorimetry, and in cell-based assays using a luciferase reporter under a consensus TEAD-binding element. Finally, we evaluated selective killing of TEAD oncogene-addicted cell lines (H226, MSTO-211 h) in vitro, and anti-tumor activity in xenografts of the same cell lines in vivo. We also evaluated interactions of TEAD inhibitors with inhibitors of other major onocogenic pathways. Results: We identified two chemical families of TEAD inhibitors with low nM cytostatic activity against TEAD-dependent cancer cell lines in vitro. Both TEAD inhibitors and literature compounds required long treatment (6-days), low cell seeding to observe biological effects, which were limited to cytostasic and not cytotoxic effects. The lead TEAD inhibitor, SPR1-TE-0294, caused rapid and dramatic tumor regression even in very large (>800 mm3) xenografted tumors. Furthermore, SPOROS TEAD inhibitors strongly interacted with MAPK pathway inhibitors in both cell lines with obvious sensitization mutation (e.g. KRAS, BRAF) and those without. Conclusions: TEAD inhibitors show exceptional anti-tumor effects in preclinical models in vivo, despite somewhat modest effects in vitro. We speculate that cell culture conditions (attachment, serum) minimize dependence on the Hippo pathway, and that TEAD inhibitors may have much broader utility than cell line-screening studies have suggested. Conflict of interest: Ownership: SPOROS Bioventures Advisory Board: SPOROS Bioventures Board of Directors: SPOROS Bioventures

BACKGROUND/AIMS:There is a close link between iron and polyamine biosynthesis and metabolism. In a recent study, we reported alterations in the serum levels of hepcidin and other iron-related proteins in Alzheimer's disease (AD) patients (Sternberg et al., 2017). Based on these findings, this pilot study compared serum levels of one of the polyamines, Spermidine, between AD, mild cognitive impairment (MCI), and control subjects, correlating the levels with the existing clinical and neuroimaging data. METHODS:This cross-sectional study measured Spermidine levels in frozen serum samples of 43 AD patients, 12 MCI patients, and 21 age-matched controls, provided by the Oregon Alzheimer's Disease Center Bio-repository, using enzyme-linked immunosorbent assay. RESULTS:MCI patients showed significantly higher mean Spermidine serum levels compared to controls (P = 0.01), with a non-significant trend for higher Spermidine serum levels in pure AD (P = 0.08) participants compared to controls. Spermidine serum levels correlated with the values of cognitive assessment tests including MMSE (r = -0.705, P = 0.003), CDR (r = 0.751, P = 0.002), and CDR-SOB (r = 0.704, P = 0.007), in "pure" AD subgroup, suggesting that higher Spermidine serum levels in MCI can be a potential biomarker of conversion to dementia in subjects with AD underlying pathology. Furthermore, Spermidine serum levels correlated with serum levels of the chief iron regulatory protein, hepcidin in AD participants with a more advanced disease stage, indicated by MMSE (strata of 8-19, P = 0.02), and CDR-SOB (strata of 6-12, P = 0.03). CONCLUSION:Studies with larger cohort are warranted for defining the role of Spermidine in AD pathophysiology, and the utility of polyamines as biomarkers of progression of MCI to AD.

There is a close link between iron and polyamine biosynthesis and metabolism. In a recent study, we reported alterations in the serum levels of hepcidin and other iron-related proteins in Alzheimer's disease (AD) patients (Sternberg, et al., 2017). Based on these findings, this pilot study compared serum levels of one of the polyamines, Spermidine, between AD, mild cognitive impairment (MCI), and control subjects, correlating with the existing neuroimaging data.

Abstract Small molecule MetAP2 inhibitor TNP-470 previously showed clinical anti-tumor activity, however CNS side effects and poor drug-like properties limited its development. SDX-7320 is a polymer-drug conjugate of a novel MetAP2 inhibitor (SDX-7539), intended to improve biodistribution (limit CNS penetration) and pharmacokinetics relative to small molecule MetAP2 inhibitors. SDX-7320 has recently completed a phase I trial in late-stage cancer patients (NCT02743637). SDX-7320 was previously shown to inhibit the growth of syngeneic EO771 triple-negative breast cancers (TNBC) accelerated by obesity/metabolic dysfunction (“metabo-oncology”). In addition SDX-7320 synergized with the PI3Kα inhibitor alpelisib (Piqray®) to block the growth of ER+/Her2- MCF-7 xenografts. Here, we show that SDX-7320 inhibits the growth of MCF-7 xenografts alone and in combination with the CDK4/6 inhibitor Palbociclib (Ibrance®). Nude mice were implanted with slow release estrogen pellets and then injected with MCF-7 cells in the fourth mammary gland. Treatment began (n=10/group) when tumors exceeded 100 mm³: SDX-7320 (sc/q4d, 8 mg/kg), palbociclib (po, qd, 20 or 40 mg/kg), SDX-7320 plus palbociclib (20 mg/kg), SDX-7320 plus palbociclib (40 mg/kg). MCF-7 tumor growth inhibition at day 31 relative to vehicle-treated mice: SDX-7320, 29% (NS); palbociclib, 24% and 54% at 20 and 40 mg/kg respectively (NS); SDX-7320 plus palbociclib (20 mg/kg), 64% (p<0.05); and SDX-7320 plus palbociclib (40 mg/kg), 82%, (p<0.01). Tumor samples were homogenized in RIPA buffer containing protease and phosphatase inhibitors for analysis of proteins (by WES). Cell-cycle proteins (cyclin E1, E2, cdk2, cdk4) were decreased in tumor tissue from SDX-7320-treated mice relative to vehicle, and were typically lower in tumors from mice treated with SDX-7320 plus palbociclib (40 mg/kg) compared to either vehicle-treated or SDX-7320-treated mice. A key growth factor-signaling protein Akt was reduced in SDX-7320-treated groups (alone and in combination) as was estrogen receptor alpha (ERα). pAkt (S473) was lowest in SDX-7320-treated tumors and in tumors treated with SDX-7320 plus palbociclib (40 mg/kg). The autophagy marker LC3B was elevated in response to palbociclib (20 and 40 mg/kg) but in combination with SDX-7320, the increase was significantly attenuated. Intracellular pathways and proteins linked to emergence of resistance to palbociclib include cell cycle (cyclin E1), growth factor and hormone signaling (Akt, ERα) and autophagy (LC3B). The protein changes observed (representative of these pathways) suggest that combining SDX-7320 with palbociclib (Ibrance®) may extend the period of progression-free survival in patients with ER+/Her2- breast cancer relative to treatment with palbociclib (Ibrance®) alone. Citation Format: Peter Cornelius, Benjamin Mayes, Pierre Dufour, Sara Little, Andrew Slee, Raphael Nir, Adam Nir, Bradley J. Carver, James Shanahan. SDX-7320, a novel inhibitor of methionine aminopeptidase 2 (MetAP2), inhibits MCF-7 tumor growth in combination with palbociclib (Ibrance®) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1068.

Mutations in the PI3K pathway have been observed in about 40% of ER+/Her2- breast cancer patients. Amplification as well as mutation of the catalytic p110α subunit of PI3K results in activation of this pathway within tumors, conferring a growth advantage due to increased transmission of intracellular growth signals. Recently a selective inhibitor of p110α, Piqray®(alpelisib) has been approved by the FDA (in combination with the estrogen receptor degrader/antagonist Faslodex/fulvestrant) for the treatment of ER+/Her2- breast cancers harboring mutation(s) in the p110α subunit of PI3K. Small molecule MetAP2 inhibitors have previously shown clinical anti-tumor activity. SDX-7320 is a polymer-drug conjugate of a novel fumagillin-derived MetAP2 inhibitor (SDX-7539) attached via a cleavable linker to a hydroxypropylmethacrylamide (HPMA) backbone. This is intended to alter biodistribution (limit CNS penetration) and improve pharmacokinetics relative to small molecule, fumagillin-derived MetAP2 inhibitors. SDX-7320 has completed a phase I trial in late-stage cancer patients (NCT02743637). The objective of this study was to evaluate the anti-tumor efficacy of Piqray®(alpelisib) in combination with SDX-7320 in a model of PI3K-mutated, ER+ breast cancer (i.e., MCF-7). Female nude mice had estrogen pellets surgically implanted and after two weeks of recovery, MCF-7 cells were injected into the fourth mammary gland. When tumors became palpable (i.e., \u003e 50 mm3) treatment with SDX-7320 (dosed subcutaneously Q4D at 8 or 16 mg/kg) and/or Piqray®(alpelisib) (dosed PO, QD at 25 or 45 mg/kg) commenced. Combinations included SDX-7320 at 8 mg/kg plus Piqray®(alpelisib) at 25 mg/kg as well as SDX-7320 at 8 mg/kg plus Piqray®(alpelisib) at 45 mg/kg. Endpoints included tumor volume, body weight, terminal plasma glucose, insulin, leptin and adiponectin. Analysis of tumor tissue for molecular endpoints of PI3K pathway activation were also investigated (e.g., S6, Akt, 4E-BP1). Anti-tumor efficacy was assessed by calculating the %change in tumor volume from baseline for each individual animal, then comparing the average change for each group at the end of the study (day 64). One-way ANOVA with multiple comparisons was conducted to determine significance of differences in final tumor volume on day 64 relative to vehicle. Treatment with SDX-7320 at 8 or 16 mg/kg inhibited MCF-7 tumor growth -19% and -17% relative to vehicle at day 64 (NS), respectively. Piqray®(alpelisib) inhibited tumor growth in a dose-dependent manner (-30% (NS) and -82% (p Citation Format: Peter Cornelius, Benjamin Mayes, Sara Little, Andrew Slee, Adam Nir, Raphael Nir, Bradley Carver, James Shanahan. Synergistic inhibition of MCF-7 mammary gland tumor growth with Piqray® (alpelisib) plus SDX-7320, a novel polymer-conjugated methionine aminopeptidase 2 (MetAP2) inhibitor [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-11-13.

Abstract Mutations in the PI3K pathway have been observed in about 40% of ER+/Her2- breast cancer patients. Amplification as well as mutation of the catalytic p110α subunit of PI3K results in activation of this pathway within tumors, conferring a growth advantage due to increased transmission of intracellular growth signals. Recently a selective inhibitor of p110α, Piqray®(alpelisib) has been approved by the FDA (in combination with the estrogen receptor degrader/antagonist Faslodex/fulvestrant) for the treatment of ER+/Her2- breast cancers harboring mutation(s) in the p110α subunit of PI3K. Small molecule MetAP2 inhibitors have previously shown clinical anti-tumor activity. SDX-7320 is a polymer-drug conjugate of a novel fumagillin-derived MetAP2 inhibitor (SDX-7539) attached via a cleavable linker to a hydroxypropylmethacrylamide (HPMA) backbone. This is intended to alter biodistribution (limit CNS penetration) and improve pharmacokinetics relative to small molecule, fumagillin-derived MetAP2 inhibitors. SDX-7320 has completed a phase I trial in late-stage cancer patients (NCT02743637). The objective of this study was to evaluate the anti-tumor efficacy of Piqray®(alpelisib) in combination with SDX-7320 in a model of PI3K-mutated, ER+ breast cancer (i.e., MCF-7). Female nude mice had estrogen pellets surgically implanted and after two weeks of recovery, MCF-7 cells were injected into the fourth mammary gland. When tumors became palpable (i.e., > 50 mm3) treatment with SDX-7320 (dosed subcutaneously Q4D at 8 or 16 mg/kg) and/or Piqray®(alpelisib) (dosed PO, QD at 25 or 45 mg/kg) commenced. Combinations included SDX-7320 at 8 mg/kg plus Piqray®(alpelisib) at 25 mg/kg as well as SDX-7320 at 8 mg/kg plus Piqray®(alpelisib) at 45 mg/kg. Endpoints included tumor volume, body weight, terminal plasma glucose, insulin, leptin and adiponectin. Analysis of tumor tissue for molecular endpoints of PI3K pathway activation were also investigated (e.g., S6, Akt, 4E-BP1). Anti-tumor efficacy was assessed by calculating the %change in tumor volume from baseline for each individual animal, then comparing the average change for each group at the end of the study (day 64). One-way ANOVA with multiple comparisons was conducted to determine significance of differences in final tumor volume on day 64 relative to vehicle. Treatment with SDX-7320 at 8 or 16 mg/kg inhibited MCF-7 tumor growth -19% and -17% relative to vehicle at day 64 (NS), respectively. Piqray®(alpelisib) inhibited tumor growth in a dose-dependent manner (-30% (NS) and -82% (p<0.05) for 25 and 45 mg/kg, respectively). The combination of SDX-7320 at 8 mg/kg with Piqray®(alpelisib) at 25 mg/kg resulted in synergistic efficacy, with -105% inhibition of tumor growth relative to vehicle at day 64 (p<0.01).The combination of SDX-7320 at 8 mg/kg with Piqray®(alpelisib) at 45 mg/kg resulted in an additive effect on tumor growth relative to vehicle (-100%; p<0.01). These results show that SDX-7320 (8 mg/kg) is synergistic with Piqray®(alpelisib; 25 mg/kg) in control of orthotopic MCF-7 mammary gland tumors. A clinical trial combining SDX-7320 with Piqray®(alpelisib) plus fulvestrant is planned to start in Q1/2020 and will assess the ability of SDX-7320 to enhance the efficacy of Piqray®(alpelisib) in treating PI3K-mutated, ER+/Her2- breast cancer. Citation Format: Peter Cornelius, Benjamin Mayes, Sara Little, Andrew Slee, Adam Nir, Raphael Nir, Bradley Carver, James Shanahan. Synergistic inhibition of MCF-7 mammary gland tumor growth with Piqray® (alpelisib) plus SDX-7320, a novel polymer-conjugated methionine aminopeptidase 2 (MetAP2) inhibitor [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-11-13.

Background/aims: Prostate specific antigen (PSA) is regulated by steroid hormones, such as testosterone, the serum levels of which are altered in patients with Alzheimer's disease (AD).This pilot study compared serum levels of the free (f) PSA between AD, mild cognitive impairment (MCI), and control subjects, and evaluated the relationship between fPSA serum levels and cognitive assessment tests and neuroimaging data. In addition, in a subgroup of AD patients, we correlated fPSA serum levels with the existing data on serum levels of amyloid-beta (AP), and iron-related proteins, including hepcidin and ferritin. Methods: Frozen serum samples from the Oregon Tissue Bank were used to measure serum levels of fPSA using enzyme-linked immunosorbent assay. Results: fPSA serum levels calculated as median SD were higher in AD males (663.6 +/- 821.0 pg/ml) compared to control males (152.0 +/- 207.0 pg/ml), p = 0.003. A similar Pattern emerged when comparing MCI males (310.7 +/- 367.0 pg/ml) to control males (P = 0.02). Correlation studies showed a significant association between fPSA and CDR (r = 0.56, P = 0.006) and CDR-SOB (r = 0.54, P = 0.009) in AD males. Conclusion: Additional studies in a larger cohort are required for determining whether fPSA can be used as biomarker of AD disease progression and whether it has the potential to identify male subjects at risk of AD dementia.

Background: We investigated Fingolimod treatment effects on the RAGE (receptor for advanced glycation endproducts) axis in multiple sclerosis (MS) patients. The primary outcome of the study was whether Fingolimod treatment increases serum levels of the soluble RAGE isoforms, sRAGE and esRAGE - both being considered putative endogenous inhibitors of RAGE signaling. Additional variables were serum levels of RAGE ligands, the high mobility group box (HMGB)1 and pentosidine. Methods: Serum levels of the study variables were measured by ELISA, and compared between baseline (before Fingolimod treatment) and 6 and 12 months post-drug treatment in 17 relapsing MS patients. Fingolimod treatment effects on MS disease progression were assessed by comparing pre- and post-Fingolimod values of the EDSS and rate of clinical relapse, and changes in the T1 -and T2-enahncing lesions on the MRI scan methods Results: Twelve months treatment with Fingolimod increased serum levels of sRAGE and esRAGE by 32.4% (P = 0.004) and 48.5% (P = 0.007) respectively. In addition, Fingolimod treatment reduced serum levels of HMGB1 by 71.6% (P = 0.02) and pentosidine serum levels by 41.3% (P = 0.12). EDSS remained stable (baseline: 3.57 +/- 1.56; post-Fingolimod: 3.54 +/- 1.2, P = 0.96) and the rate of clinical relapse decreased near significantly (P = 0.094). T1-and T2-enhancing lesions remained stable, showing no significant changes pre-vs. post-Fingolimod treatment. Conclusion: Fingolimod mediates modulation of the RAGE axis which apparently contributes to the Fingolimod's anti-inflammatory and neuroprotective effects. These findings may provide a rationale for the clinical efficacy of Fingolimod in pathological states other than MS, where dysregulation of the RAGE axis plays a role. (C) 2017 Elsevier Ltd. All rights reserved.

Abstract Radiation therapy is an established therapeutic option for lung cancer, but its use is limited due to side effects. Combining radiosensitizers with RT is a way to augment the efficacy of RT. Chromosome Region Maintenance Protein 1/Exportin 1 (CRM1/XPO1) is a key nuclear export protein, the cargoes of which are Tumor Suppressor Proteins (TSPs) such as p53, FOXO, PTEN, pRB and I-κB. Small molecule SINE block CRM1-dependent nuclear export and force the nuclear retention of TSPs, potentially sensitizing cells to RT. Suggested mechanisms include: 1) Induction of “genome fidelity review” by forced nuclear retention of TSPs; 2) Prevention of single stranded DNA break repair, and thereby reduction of resistance of cancer cells to RT. Methods: IC50 of KPT-SINE e.g. KPT-185 and clinical compound KPT-330, were determined in MTT assays using human NSCLC p53 wild type (wt) cancer cell lines H1299 and A549. Clonogenic assays in the SINE sensitive H1299 (IC50 100nM) and SINE-resistant A549 (IC50 1.7μM) lines were conducted in the presence or absence of escalating doses of radiation. An in vivo tumor xenograft model using the A-549 cell line in SCID mice was also conducted with KPT-330. Results: KPT-185 demonstrated inhibitory effects on the clonogenicity of two NSCLC cell lines in a dose dependent fashion. We showed that, while RT alone treatment caused coloines growing curve reduced to less than <40% of colonies in both cell lines. Combination of both agents (RT and SINE at IC25 concentrations) demonstrated an additive effect for A549 cell line, and a dose-related effect for H1299 cell line. In vivo, we demonstrated significant reductions in tumor growth, where treatment with KPT-330 caused a >75% tumor volume reduction when compared to vehicle, and a >65% reduction when compared to Cisplatin. In this model, KPT-330 was fairly well-tolerated, with minimal body weight loss by animals over the course of the study. Conclusions: These studies showed that KPT-SINE significantly inhibited the growth of two p53 wt NSCLC lines by MTT assay. Similar inhibition was observed in clonogenic assays with cells (A549) resistant to SINE. We described the additive effects of SINE and RT on NSCLC cell lines, suggesting that SINEs can act as radiosensitizers. We further demonstrated that SINEs are efficacious in vivo in the A549 xenograft model, and display superior efficacy when compared to Cisplatin. SINE compounds represent a promising novel therapy against NSCLC both as stand-alone agents and in combination with RT. These data support further development of SINE-based therapies for NSCLC. Further work on in vivo studies of KPT-SINE in combination with RT will be reported. Citation Format: Tami Rashal, Dilara McCauley, Maya Ilouze, Nir Raphael, Inessa Solomonik, Yaccov Lawrence, Ronen Shavit, Sharon Shacham, Michael Kauffman, Nir Peled. Combination tTerapy KPT-SINE (selective inhibitors of nuclear export) with radiotherapy have additive effects in non-small cell lung cancer (NSCLC) cells in vitro and in vivo. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2075. doi:10.1158/1538-7445.AM2013-2075

Abstract Neoplastic cells must inactivate their tumor suppressor proteins (TSP) in order to perpetuate their growth. Oncogene and growth factor driven nuclear export of TSPs is an increasingly recognized mechanism for TSP inactivation. We have developed orally active, small molecule SINE that irreversibly block the major nuclear export protein CRM1 (exportin 1, XPO1) and selectively induce the death of cancer cells. Forced nuclear accumulation of TSPs is believed to initiate a “genome survey” leading to the death of cancer cells, whereas normal cells undergo transient, reversible cell cycle arrest. We show that the small molecule SINE CRM1 inhibitor KPT-185 potently kills many types of tumor cells in vitro (IC50 20-500nM, IC80 ≤ 1µM at 72 hours) including ∼75% of NSCLC lines with diverse genetic signatures (EGFR wt & mut, p53 wt & mut, K-ras wt & mut). In contrast, ∼25% of NSCLC lines with similar genotypes show cytotoxicity IC50s ≤ 1.5µM and IC80 is not reached. Treatment of the SINE-resistant A549 NSCLC (adenocarcinoma, EGFR wt, p53 wt, K-ras mut, KPT-185 IC50 = 1.75µM) leads to nuclear localization of p53, p21, FOXO, E2F4, IkB, underphosphorylated pRb and other CRM1 cargoes at concentrations similar to that of sensitive NSCLC cell lines, but apoptosis is not readily induced. To test whether the resistance to CRM1 inhibition-mediated cytotoxicity is due to activation of anti-apoptotic (or inactivation of pro-apoptotic) BCL-2 family proteins, we combined SINE with ABT-737, a small-molecule BCL-2 inhibitor currently in Phase 2 clinical trials, and examined the molecular mechanisms leading to tumor cell death. We show that combination of low doses (500nM, the IC20) of KPT-185 with non-cytotoxic doses of the Bcl-2 inhibitor (≥ 100µM) induces synergistic cytotoxicity. Moreover, the antitumor effects of the combination therapy are manifested within 48 hours, whereas significant cytotoxicity by higher doses of SINE alone requires at least 72 hours. Similar results have been obtained with another SINE resistant cell line, HCC-2935 (EGFR mut, p53 mut, K-ras mut). We noted that in the resistant A549 line, levels of the pro-apoptotic BCL2 member, Bax, were reduced by ∼50% with SINE treatment, but that addition of the BCL2 inhibitor reversed this effect and induced significant synergistic cytotoxicity. The sensitive NSCLC cell line H-226 (EGFR wt, p53wt, K-ras wt; IC50 12nM) showed nuclear localization of CRM1 cargoes when treated with KPT-185 (100nM), but only modest additional killing by the addition of the Bcl-2 inhibitor. We conclude that mechanism of resistance to SINE mediated cytotoxicity can be overcome by antagonism of Bcl-2. In vivo studies using A-549 xenografts comparing the effects of KPT-SINE and ABT-737 alone or in combination are ongoing and will be reported at the meeting. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1831. doi:1538-7445.AM2012-1831

Abstract Chromosome Region Maintenance 1/Exportin-1 (CRM1) is a key nuclear export protein whose inhibition leads to the nuclear accumulation of TSPs and negative regulators of cell proliferation. Through CRM1 inhibition, nuclear localization of these proteins restores cell cycle checkpoints and genome surveying functions culminating in apoptosis of tumor cells. Conversely, CRM1 inhibition of normal cells induces reversible cell cycle arrest. We are developing novel small molecules, KPT-SINE, which irreversibly bind and inhibit CRM1 nuclear export killing a broad range of tumor cell lines and xenografts. We used human colon cancer cells HCT116 to track the molecular and cellular events that follow KPT-SINE treatment and ultimately lead to cancer cell death. Methods: Using our proprietary in silico hierarchical structure-based discovery platform, we designed and tested novel SINE in a cell-based microscopy assay to confirm CRM1-mediated nuclear export inhibition. Cytotoxic IC50s of KPT-SINE were determined on a panel of cancer cell lines. KPT-SINE – KPT-185, -251 and -276 were selected for additional testing based on their potency and pharmacokinetics. These include; 1. Nuclear localization of TSPs, 2. Effects on cell cycle and viability, 3. Effects on TSP mRNA and protein expression. Additionally, we transiently transfected mutant CRM1-C528S into cells and treated with KPT-SINE to show binding to Cysteine 528. We tested the effects of KPT-276 in an in vivo HCT116 xenograft model. Results: KPT-276, a potent inhibitor in the cell-based microscopy assay (EC50 = 130 nM), was a robust inhibitor of HCT116 proliferation (IC50 = 400 nM). KPT-SINE inhibition of CRM1 started within 30 minutes and reached a maximum in 8 hrs. Additionally, KPT-SINE effects were blocked by transient transfection of CRM1-C528S, confirming KPT-SINE - Cysteine 528 interaction. Washout experiments demonstrated that 4 hrs of KPT-SINE incubation sustained 24 hrs of CRM1 inhibition. We also identified nuclear accumulation of p53, FOXO3a, pRb, APC, IαB, p27, PTEN, and p21, which was followed by cell cycle arrest and cell death. Although KPT-276 treatment had less effect on cell cycle and cytotoxicity assays of p53null HCT116 cells, the p53 wildtype and null HCT116 cells showed similar kill curves after 8 days of treatment. Mouse xenografts treated with 75 mg/kg QDX5 of KPT-276 each week for 4 weeks inhibited tumor growth by more than 70%. Further analysis of the tumor molecular markers from KPT-276 treated animals will be reported. Conclusions: In this study we described the correlative effects of KPT-SINE from the accumulation of nuclear TSPs through to cancer cell death in mouse models. These results suggest that KPT-SINE display potent in vivo efficacy in the xenograft model of human colon cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2943. doi:1538-7445.AM2012-2943

1055 Background: Basal-like breast cancers (BLBC) compose up to 15% of breast cancer (BC) and are usually triple negative characterized by lack of ER, PR, and HER-2 amplification. In addition, most BRCA1-associated BCs are BLBC and TNBC, expressing basal cytokeratins and EGFR. BLBC is characterized by an aggressive phenotype, high histological grade, and poor clinical outcomes: high recurrence and metastasis rates. CRM1 (XPO1) is the exclusive nuclear exporter of multiple Tumor Suppressor Proteins (TSP) including p53, p21, BRCA1&2, pRB, FOXO. CRM1 inhibition forces nuclear accumulation of TSPs, inducing apoptosis in cancer cells. KPT-SINE are novel, small molecule, irreversible inhibitors of CRM1 with potent anti cancer activity. Methods: The Cancer Genome Atlas (TCGA) and BC cell line databases were used for mRNA analyses. MTT assay was used to determine the cytotoxic effect of KPT-SINE (KPT-185 and KPT-330) on 44 breast cell lines including luminal A, luminal B, HER2 positive, BLBC and TNBC cells. The effect of KPT-330 treatment on tumor growth was tested in vivo in the TNBC model MDA-MB-468 xenograft. Results: Analyses of nuclear pore complex (NPC)-related mRNA levels (including CRM1) showed clear separation of BCs into high and low NPC expression. BLBC subtype was enriched with high NPC transcripts while luminal BC was enriched in low NPC levels (p<1.53e-20). High NPC levels had higher mutation levels in BRCA2 (cor=0.33, p=1.83e-8) and ABL1. NPC expression was inversely correlated with ER mRNA expression (cor=-0.58, p=1.37e-7). KPT-SINE showed potent cytotoxicity on >75% of the cell lines (IC50 values <1 μM). Only three of 24 TNBC cell lines displayed IC50 values >1.5 μM upon KPT-SINE treatment. Genomic analyses on all BC lines indicated that p53, PI3K/AKT and BRCA1 or 2 status did not affect cytotoxicity. In MDA-MB-468 xenograft, KPT-330 displayed efficacy in a dose-dependent manner inhibiting nearly 100% of tumor growth compared with vehicle treated animals, and was well tolerated. Conclusions: These data show that NPC/CRM1 mRNAs are overexpressed in BLBC/TNBC and that CRM-1 mediated nuclear export inhibition by SINE represents a potentially novel and well tolerated therapy for BLBC / TNBC.

430 Background: CRM1 (XPO1) is a key nuclear export protein which controls the location of multiple tumor suppressor (TSP) and growth regulatory (GRP) proteins including p53, PI3K/AKT, Wnt/ß-catenin and NF-kB. Forced nuclear expression of TSP and GRP by CRM1 inhibition can lead to apoptosis in cancer cells while sparing normal cells. METHODS Novel small-moleculeCRM1 inhibitors were synthesized and nuclear distribution studies were performed in cells transfected with HIV-rev GFP proteins. Cell proliferation studies were performed in 16 CRC cell lines: LS-123, SW-626, Colo-201, Colo-205, Colo-320DM, Colo-320HSR, Lovo, DLD-1, HCT-15, WiDi, LS-174T, LS-180, SW-620, C2BBe1, HCT-8, HCT-116, and in human peripheral leukocytes (PBMC). Cellular distribution and apoptosis assays were performed on HCT-116. Antitumor activity is assessed in human HCT-116 xenografts in scid-mice. RESULTS The lead CRM1 inhibitor, KPT-0127, blocks CRM1 mediated nuclear export of HIV-Rev-GFP, FOXO, and p53 with an IC50 of ∼300 nM. KPT-0127 is cytotoxic to various CRC cell lines with EC50s of 0.07-1.1 μM; in 9 CRC lines EC50s were < 0.3 mM. In contrast, normal cell lines and PBMCs had EC50 > 5-20 μM. In HCT- 116 cells, KPT-0127 induces cell cycle arrest at both G1/S and G2/M checkpoints and dose dependently increases nuclear p53, followed by an increase in caspase 3. KTP-0127 10μM shows no significant effect on 37 proteins including several cysteine proteases. In mice, KPT-0127 given by SC injection of 30-100 mg/kg leads to serum levels exceeding the effective CRM1 inhibitory concentration for at least 4 hours and is well tolerated. KPT-0127 given SC to mice bearing HCT-116 colon xenografts results in dose-dependent antitumor activity. CONCLUSIONS The novel small- molecule CRM1 inhibitor KTP-0127 kills CRC lines with multiple TSP, GRP, and oncogenic abnormalities, including p53 mutations/deletions and PTEN deficiency/AKT activation, while sparing normal cells. This likely reflects the ability of CRM1 inhibition to affect multiple critical and non-redundant regulatory pathways. These results support the development of CRM1 inhibitors for the treatment of CRC. IND-enabling CMC and toxicology work are in preparation. [Table: see text].

Abstract Transport of macromolecules across nuclear membrane is fundamental to the proper functioning of living cells. Nuclear localization of intact tumor suppressor proteins (TSPs) and other growth regulatory proteins (GRPs) such as p53, FOXO, pRB, p21, p27 and IκB are critical for their “policing” function. Conversely, mislocalization of a nuclear protein to the cytoplasm can render it ineffective as a TSP/GRP. Cancer cells appear to acquire intracellular mechanisms to export tumor-supressing nuclear proteins as they evolve and spread. In many cases, nuclear export is followed by proteasome dependent degradation. Most known TSP/GRP utilize the nuclear export protein CRM1 (chromosomal region maintenance 1; also called exportin 1 [XPO1]), to exit the nucleus, and overexpression of CRM1 has been reported as a poor prognostic factor in a variety of neoplasms. Therefore, inhibition of CRM1 can force the nuclear localization of key TSPs/GRPs, activating their pathways. This leads to cell cycle arrest followed by induction of cell death in cancer cells. Our SINE are novel, potent and selective, drug-like nuclear export inhibitors (IC50 ∼40-100nM) that derive their activity through direct covalent modification and inhibition of CRM1. SINE exert selective and prolonged inhibition of CRM1-mediated forkhead (FOXO), p53, p21 and IκB nuclear export in a variety of normal and transformed cell lines. Cell cycle analysis following incubation with the SINE compound KPT-0127 revealed that it blocks at both the G1/S and G2/M phases, consistent with arrest at multiple cell cycle checkpoints. SINE-induced apoptosis is observed in many cancer cell lines (e.g. A375, Jurkat, BL-40, HCT-116), but not in normal proliferating cells (e.g. 3T3, mouse embryo fibroblasts). In cytotoxicity assays, SINE compounds showed highly potent cytotoxicity in both hematologic and solid tumor cell lines (IC50s <100nM) with limited effects on normal cells (PBMCs, HUVEC, 3T3, MEF IC50s >2000nM). SINE show no significant effect on 37 proteins including several cysteine proteases, minimal CYP inhibition (> 10 μM for all major CYPs) and no hERG inhibition. In single dose mouse toxicology studies, KPT-0127 was generally well tolerated (p.o. or s.c.) up to 560 mg/kg, and no deaths were observed. The pharmacokinetics of KPT-0127 is adequate for s.c. and i.v. dosing in vivo. Tumor xenograft studies have been undertaken in colon cancer HCT-116 and myeloma MM.1S tumor bearing mice. SINE induce potent, dose dependent anticancer activity against both small (∼140mm3) and large (∼1400mm3) tumors. Together, these data demonstrate that SINE represent a novel mechanism of action with robust anti-tumor activity both in vitro and in vivo and promising applications as single agent and for combination therapies. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2580. doi:10.1158/1538-7445.AM2011-2580

e14091 Background: In order to maintain their malignant phenotype, neoplastic cells must neutralize most of their tumor suppressor (TSP) and growth regulatory (GRP) proteins. CRM1, also called exportin 1, mediates the nuclear export of the majority of TSP/GRP, leading to their inactivation. Blockade of CRM1 with SINE induces cytotoxicity in neoplastic cells, but only reversible cell cycle arrest in normal cells. We report on the potential of SINE for the treatment of molecular subtypes of CRC. Methods: KPT-127 is a moderate potency, small-molecule SINE with broad-spectrum, tumor-selective cytotoxicity in vitro and in vivo tolerability. Twenty human CRC cell lines with distinct genotypes were tested for KTP-127-induced cytotoxicity after 72 hours using MTT assay. Mouse embryo fibroblasts (MEF) were cycling, normal controls. Genetic profiles of cells were obtained from the literature. In vivo efficacy and tolerability of KPT-127 were evaluated in HCT-116 xenografts. Results: Cytotoxicity IC50s were determined for the 20 CRC lines, and they were grouped into most quartiles, and the genotypes of most sensitive (<300nM) and most resistant (>1200nM) determined. The status of p53 or APC, or the presence of p16 methylation, K-ras mutations, microsatellite instability (MSI), EGFR, or Pgp (mdr1) did not correlate with killing by KPT-127. Moreover, HCT-116 p53Ð/Ð variant CRC line cytotoxicity was similar to that of the parenteral (p53+) line. Consistent with its action as an irreversible CRM1 inhibitor, expression of the multidrug resistance pump Pgp1 also did not affect KPT-127 potency. In HCT-116 xenografts, KTP-127 150mg/kg induced >80% tumor growth inhibition similar to irinotecan 30mg/kg twice weekly but without causing myelosuppression or other toxicities. Conclusions: KTP-127, a SINE that irreversibly blocks CRM1, kills a variety of CRC cell lines regardless of commonly used molecular prognostic markers including p53, K-ras, and Pgp status. KPT-127 has minimal effects on normal cells and is well tolerated with significant antitumor activity in vivo. More potent SINEs with improved pharmacokinetic profiles are being developed for clinical use as single agents and in combination.

Abstract CRM1 (Xpo1) is the major export factor for proteins from the nucleus to the cytoplasm, including tumor suppressors (TSPs) and other modulators of proliferative responses such as p53, FOXO, c-Abl, pRB and IκB. Leptomycin B (LMB), a non-drug like natural product is a potent inhibitor of CRM1-mediated nucleocytoplasmic transport. LMB and related analogs trap TSPs and other proteins in the nucleus, forcing neoplastic cells into apoptosis while normal cells undergo reversible cell cycle arrest. However, LMB has limited efficacy in vivo due to its severe gastrointestinal toxicity. Here, we describe our lead compound KPT-0127 a novel small molecule, water soluble, drug-like, selective, irreversible CRM1 antagonist. Like LMB, KPT-0127 forms a covalent bond with Cys528 in the CRM1 cargo-binding pocket, abrogating most, but not all, export functions of CRM1. KPT-0127 exerts a potent (EC50 300-400nM) and prolonged inhibition of CRM1- mediated HIV-1 Rev, forkhead (FOXO), and p53 nuclear export in a variety of normal and transformed cell lines. In cytotoxicity assays, KPT-0127 showed high potency in most hematologic cancer cell lines (EC50 <500nM, with leukemia and lymphoma lines often <100nM) and variable activity in solid tumor cell lines (EC50 90-2000nM), with colon and melanoma cells being the most sensitive (EC50< 100 nM). By contrast, normal cells were largely unaffected by treatment with KPT-0127 (EC50 >5-10µM). Studies in the HCT-116 colon cancer cell line suggested that KPT-0127 dose dependently increases the nuclear levels of p53 and appears to induce cell cycle arrest at both the G1/S and G2/M checkpoints, prior to inducing apoptosis. In normal peripheral blood mononuclear cells (PBMCs) and in Hut78 leukemia cells, KPT-0127 potently increased the nuclear levels of IκB. However, KPT-0127 induced cell death of Hut78 cells with no effect on normal PBMCs. In drug combination studies, KPT-0127 showed additive or synergistic cytotoxicity activity with either 5-FU, carboplatin, or doxorubicin. Mechanism of action studies demonstrated that the Cys528 residue in the cargo-binding pocket of CRM1 is essential for the inhibitory effect of KPT-0127. Mutagenesis of Cys528 to a Ser completely abrogated KPT-0127 inhibition. KPT-0128, the transisomer of KPT-0127, shows little effect on both HIV-Rev nuclear export and in cytotoxicity assays (EC50s > 10μM), supporting the specificity of KPT-0127 for CRM1. Moreover, the selectivity of KTP-0127 was demonstrated across a panel of 37 proteins including several cysteine proteases. In single dose mouse toxicology studies, KPT-0127 was generally well tolerated (oral or SC) up to 560 mg/kg, and no deaths were observed. SC dosing daily for 5 days up to 100mg/kg (the highest dose tested) showed no behavioral, clinical chemistry, or hematogical effects in mice; Pharmacokinetics of KPT-0127 is adequate and in vivo efficacy studies are currently being performed; results will be presented. All together, these data demonstrate that KPT-0127 represents a novel, tumor selective, and well-tolerated irreversible Crm1 inhibitor which may be suitable for clinical development both as a single agent and in combination with standard therapies. Citation Information: Clin Cancer Res 2010;16(14 Suppl):A19.

Abstract Abstract 3012 Background: CRM1 (XPO1) is a key nuclear export protein which controls multiple tumor suppressor proteins (TSP) and cell proliferation pathways including p53, PI3K/AKT, Wnt/ß-catenin and NF-kB. Further, mislocalization of proteins can abrogate TSP functions and render chemotherapies ineffective. For example, multiple myeloma (MM) cells that are grown at high densities (to mimic the in vivo situation) become resistant to topoisomerase 2 (topo2) inhibitors (e.g., doxorubicin) simply because topo2α is exported from the nucleus. Forcing the nuclear expression of chemotherapy targets, TSP and growth regulatory proteins by CRM1 inhibition can restore drug sensitivity and restore checkpoint control/genome surveying functions. These events lead to apoptosis or autophagy in cancer cells while sparing normal cells. Methods: CRM1 inhibitors were synthesized and nuclear distribution studies were performed in U2OS cells transfected with HIV-rev GFP proteins. Cell proliferation studies were performed in multiple myeloma (MM), leukemia and lymphoma cell lines and in human peripheral blood mononuclear cells (PBMCs). Toxicology studies were performed in several mouse strains. Antitumor activity is assessed in a xenograft model of human MM.1 cells growing in scid-mice. Results: The lead CRM1 inhibitor, KPT-0127, blocks CRM1 mediated nuclear export of HIV-Rev-GFP, FOXO, and p53 with an IC50 of ~300 nM. KPT-0127 is selectively cytotoxic to various hematological cell lines with EC50s in the 0.02–1.0 μM range, and shows limited cytotoxicity in similar studies in normal cell lines (NIH-3T3, MRC5, HUVECs) and PBMCs (EC50 >5-20 μM). KPT-0127 increases the nuclear localization of IkB in HUT-78 leukemia cells and human PBMCs, and inhibits TNF-α secretion in LPS stimulated U937 macrophage derived cells, likely through inhibition of NF-kB signaling. In MM cells grown at high densities which actively export topo2 to the cytoplasm via CRM1, blocking CRM1-dependent transport strongly enhanced topo2 nuclear localization and augmented the apoptotic effects of doxorubicin in <24 hours showing clear synergy between KPT-0127 and the anthracycline. Combination of sublethal concentrations of bortezomib plus KPT-0127 in MM1.S and MM.1R myeloma cells (as well as in Jurkat and HS-Sultan) induced synergistic cytotoxicities. In mice, KPT-0127 given by subcutaneous (SC) injection of 30–100 mg/kg leads to serum levels exceeding the effective CRM1 inhibitory concentration for at least 4 hours. In 5 day repeated dose toxicology studies, SC administration of 100 mg/kg KPT-0127 (QD × 5) was well tolerated in mice with no cutaneous or obvious systemic clinical findings. Modest neutrophilia and mild lymphopenia were seen and no neurologic signs resulted from treatment with KPT-0127. Administration of KPT-0127 SC to mice bearing HCT-116 colon cancer results in dose-dependent antitumor activity. Xenograft studies with MM.1 myeloma cells are underway and will be presented at the meeting. Conclusions: The sensitivity of tumors with multiple TSP and oncogenic abnormalities, including p53 mutations/deletions and PTEN deficiency/AKT activation, to killing with KPT-0127 likely reflects the ability to affect multiple critical and non-redundant regulatory pathways. CRM1 inhibition also forces topo 2 to remain in the nucleus, and increases levels of nuclear IkB antagonizing NF-kB function, thereby reducing the likelihood of resistance development. These results support the development of small molecule, drug-like CRM1 inhibitors for the treatment of MM and other hematological cancers. IND-enabling CMC and toxicology work are expected to begin in early 2011. Disclosures: Shacham: Karyopharm: Employment, Equity Ownership, Patents & Royalties. Nir:Karyopharm: Consultancy. Draetta:Karyopharm: Consultancy. Sandanayaka:Karyopharm: Employment. Shechter:Karyopharm: Employment. Kauffman:Karyopharm: Consultancy, Equity Ownership, Patents & Royalties.