Investigation of the anti-tumor mechanism of tirabrutinib, a highly selective Bruton's tyrosine kinase inhibitor, by phosphoproteomics and transcriptomics

Tirabrutinib is a highly selective Bruton's tyrosine kinase (BTK) inhibitor used to treat hematological malignancies. We analyzed the anti-tumor mechanism of tirabrutinib using phosphoproteomic and transcriptomic methods. It is important to check the drug's selectivity against off-target proteins to understand the anti-tumor mechanism based on the on-target drug effect. Tirabrutinib's selectivity was evaluated by biochemical kinase profiling assays, peripheral blood mononuclear cell stimulation assays, and the BioMAP system. Next, in vitro and in vivo analyses of the anti-tumor mechanisms were conducted in activated B-cell-like diffuse large B-cell lymphoma (ABC-DLBCL) cells followed by phosphoproteomic and transcriptomic analyses. In vitro kinase assays showed that, compared with ibrutinib, tirabrutinib and other second-generation BTK inhibitors demonstrated a highly selective kinase profile. Data from in vitro cellular systems showed that tirabrutinib selectively affected B-cells. Tirabrutinib inhibited the cell growth of both TMD8 and U-2932 cells in correlation with the inhibition of BTK autophosphorylation. Phosphoproteomic analysis revealed the downregulation of ERK and AKT pathways in TMD8. In the TMD8 subcutaneous xenograft model, tirabrutinib showed a dose-dependent anti-tumor effect. Transcriptomic analysis indicated that IRF4 gene expression signatures had decreased in the tirabrutinib groups. In conclusion, tirabrutinib exerted an anti-tumor effect by regulating multiple BTK downstream signaling proteins, such as NF-κB, AKT, and ERK, in ABC-DLBCL.

Organic modification of layered zirconium phosphate/phosphonate for controlled release of therapeutic inorganic ions

The present study aims to develop a layered zirconium phosphate/phosphonate (LZP) powder to control the release of therapeutic inorganic ions. Organically modified LZPs were successfully prepared with various contents of phenyl groups via a reflux method in an aqueous solution containing phosphoric and phenylphosphonic acids. Powder X-ray diffraction analysis and Fourier transform infrared spectroscopy revealed that the crystal structure of the synthesized LZP samples was identical to that of α-zirconium phosphate, even after modification. The amount of incorporated organic molecules increased with increasing molar fractions of phenylphosphonic acid in the starting composition, as determined from the thermal analysis. Cobalt ion (Co2+), a type of therapeutic inorganic ion, was incorporated into the organically modified LZP through treatment with an acetonitrile solution containing tetrabutylammonium ions, followed by treatment with an acetonitrile solution containing CoCl2. The amount of incorporated Co2+ depended on the concentration of the phenyl groups. Furthermore, the highest amount of Co2+ was incorporated in the sample (ZP-Ph-0.5) prepared with equimolar phosphoric/phenylphosphonic acid. The ZP-Ph-0.5 sample additionally showed the ability to incorporate copper or iron ions (Cu2+ or Fe3+). The incorporated ion, either Co2+ or Cu2+, was continuously released from the ZP-Ph-0.5 sample in a saline solution over a period of three weeks, whereas the release of Fe3+ was negligible. The quantity of Co2+ released was higher than that of Cu2+. The controlled release of Co2+ from the ZP-Ph-0.5 sample was also observed in a simulated body fluid that mimicked the ionic concentration of human blood plasma. These results confirm that a specific degree of phenyl modification makes LZP a candidate host material for releasing therapeutic inorganic ions.

AXL/MERTK inhibitor ONO-7475 potently synergizes with venetoclax and overcomes venetoclax resistance to kill FLT3-ITD acute myeloid leukemia

FMS-like Tyrosine Kinase 3 (FLT3) mutation is associated with poor survival in acute myeloid leukemia (AML). The specific Anexelekto/MER Tyrosine Kinase (AXL) inhibitor, ONO-7475, kills FLT3-mutant AML cells with targets including Extracellular-signal Regulated Kinase (ERK) and Myeloid Cell Leukemia 1 (MCL1). ERK and MCL1 are known resistance factors for Venetoclax (ABT-199), a popular drug for AML therapy, prompting the investigation of the efficacy of ONO-7475 in combination with ABT-199 in vitro and in vivo. ONO-7475 synergizes with ABT-199 to potently kill FLT3-mutant acute myeloid leukemia cell lines and primary cells. ONO-7475 is effective against ABT-199-resistant cells including cells that overexpress MCL1. Proteomic analyses revealed that ABT-199-resistant cells expressed elevated levels of pro-growth and anti-apoptotic proteins compared to parental cells, and that ONO-7475 reduced the expression of these proteins in both the parental and ABT-199-resistant cells. ONO-7475 treatment significantly extended survival as a single in vivo agent using acute myeloid leukemia cell lines and PDX models. Compared to ONO-7474 monotherapy, the combination of ONO-7475/ABT-199 was even more potent in reducing leukemic burden and prolonging the survival of mice in both model systems. These results suggest that the ONO-7475/ABT-199 combination may be effective for AML therapy.

Pharmacokinetic-Pharmacodynamic-Efficacy Modeling of ONO-7579, a Novel Pan-Tropomyosin Receptor Kinase Inhibitor, in a Murine Xenograft Tumor Model

The orally available and novel small molecule ONO-7579 (N-{2-[4-(2-amino-5-chloropyridin-3-yl)phenoxy]pyrimidin-5-yl}-N'-[2-(methanesulfonyl)-5-(trifluoromethyl)phenyl]urea) is a highly potent and selective pan-tropomyosin receptor kinase (TRK) inhibitor. The objective of the present study was to characterize the pharmacokinetic (PK), pharmacodynamic (PD), and antitumor efficacy relationships of ONO-7579 in mice xenografted with a human colorectal cancer cell line, KM12 (harboring the tropomyosin 3 (TPM3) -neurotrophic tyrosine receptor kinase 1 fusion gene), via a PK/PD modeling approach. Plasma and tumor concentrations of ONO-7579, tumor levels of phosphorylated TPM3-TRKA (pTRKA), and tumor volumes in the murine model were measured with a single or multiple dose of ONO-7579 (0.06-0.60 mg/kg) administered once daily. The PK/PD/efficacy models were developed in a sequential manner. Changes in plasma concentrations of ONO-7579 were described with an oral one-compartment model. Tumor concentrations of ONO-7579 were higher than plasma concentrations, and changes in ONO-7579 tumor concentrations were described with an additional tumor compartment that had no influence on plasma concentrations. pTRKA in tumors was described with a direct E_max model, and the tumor ONO-7579 concentration causing 50% of the maximum effect was estimated to be 17.6 ng/g. In addition, a pTRKA-driven tumor growth inhibition model indicated that ONO-7579 started to sharply increase the antitumor effect at pTRKA inhibition rates >60% and required >91.5% to reduce tumors. In conclusion, the developed PK/PD/efficacy models revealed a "switch-like" relationship between pTRKA inhibition rate and antitumor effect in a murine KM12 xenograft model, demonstrating that pTRKA in tumors could serve as an effective biomarker for scheduling the dose regimen in early-stage clinical studies. SIGNIFICANCE STATEMENT: In recent years, clinical development of TRK inhibitors in patients with neurotrophic tyrosine receptor kinase fusion-positive solid tumors has been accelerated. This research found that phosphorylated TRKA was a useful biomarker for explaining the antitumor efficacy of TRK inhibitors using a pharmacokinetic/pharmacodynamic modeling approach in xenograft mice. This finding suggests a rational dosing regimen in early-stage clinical studies for ONO-7579 (N-{2-[4-(2-amino-5-chloropyridin-3-yl)phenoxy]pyrimidin-5-yl}-N'-[2-(methanesulfonyl)-5-(trifluoromethyl)phenyl]urea), a novel pan-TRK inhibitor.

ONO-7475, a Novel AXL Inhibitor, Suppresses the Adaptive Resistance to Initial EGFR-TKI Treatment in EGFR-Mutated Non-Small Cell Lung Cancer

PURPOSE

Currently, an optimal therapeutic strategy comprising molecularly targeted agents for treating EGFR-mutated non-small cell lung cancer (NSCLC) patients with acquired resistance to osimertinib is not available. Therefore, the initial therapeutic intervention is crucial for the prolonged survival of these patients. The activation of anexelekto (AXL) signaling is known to be associated with intrinsic and acquired resistance to EGFR tyrosine kinase inhibitors (EGFR-TKIs). In this study, we investigated the best therapeutic strategy to combat AXL-induced tolerance to EGFR-TKIs using the novel AXL inhibitor ONO-7475.

EXPERIMENTAL DESIGN

We examined the efficacy of ONO-7475 in combination with EGFR-TKIs in EGFR-mutated NSCLC cells using in vitro and in vivo experiments. We investigated the correlation between AXL expression in tumors and clinical outcomes with osimertinib for EGFR-mutated NSCLC patients with acquired resistance to initial EGFR-TKIs.

RESULTS

ONO-7475 sensitized AXL-overexpressing EGFR-mutant NSCLC cells to the EGFR-TKIs osimertinib and dacomitinib. In addition, ONO-7475 suppressed the emergence and maintenance of EGFR-TKI-tolerant cells. In the cell line-derived xenograft models of AXL-overexpressing EGFR-mutated lung cancer treated with osimertinib, initial combination therapy of ONO-7475 and osimertinib markedly regressed tumors and delayed tumor regrowth compared with osimertinib alone or the combination after acquired resistance to osimertinib. AXL expression in EGFR-TKI refractory tumors did not correlate with the sensitivity of osimertinib.

CONCLUSIONS

These results demonstrate that ONO-7475 suppresses the emergence and maintenance of tolerant cells to the initial EGFR-TKIs, osimertinib or dacomitinib, in AXL-overexpressing EGFR-mutated NSCLC cells, suggesting that ONO-7475 and osimertinib is a highly potent combination for initial treatment.

Abstract 1883: A novel Axl and Mertk dual inhibitor ONO-7475: A new therapeutic agent for the treatment of FLT3-ITD and -wild-type acute myeloid leukemia (AML) overexpressing

Introduction: The TAM (Tyro3, Axl, and Mertk) receptor tyrosine kinases (RTKs) together with their ligands Gas6 and Pros1 play diverse roles in survival signaling in cancers. Currently, the consensus indicates that therapeutic targeting of TAM RTKs will prove direct antitumor activity and may complement existing immunotherapy regimens to unleash the full power of the anticancer immune response. A number of small-molecule kinase inhibitors targeting TAM RTKs are being developed and tested in preclinical models. ONO-7475 is a highly potent and oral dual inhibitor of Axl and Mertk, currently in a phase 1 clinical study as a therapeutic agent for AML (NCT03176277). Our previous studies demonstrated that ONO-7475 induced complete tumor remission in the FLT3-internal tandem duplication (ITD)-positive AML cell line MV-4-11 mouse xenograft model (Yasuhiro et al., Blood 2014). However, the antitumor activity against FLT3-ITD AML cells was due to Axl inhibition (Ruvolo et al., Haematologica 2017) and the mechanism of Mertk regulation in AML has not been determined. To evaluate this question, we screened 28 AML-derived cell lines for FLT3-wild type (WT) and analyzed the influence of Mertk in proliferation.

Methods: Twenty-eight FLT3-WT AML cell lines were treated with ONO-7475 for 72 hours, and the cell viabilities (IC50 values) were determined. Phospho-Axl (P-Axl), Axl and Mertk were determined by Western blot analysis. P-Mertk was determined by immunoprecipitation. Gene knockdown was achieved in FLT3-WT AML by transfecting with Axl, Mertk, Gas6, Pros1, or scrambled control siRNA.

Results: Six out of 28 FLT3-WT cell lines responded to ONO-7475, and two cell lines, MOLM16 and MKPL1, were highly sensitive (IC50: 4.7nM and 83.5nM). Western blot analysis demonstrated that Axl, Mertk and P-Mertk were overexpressed in these ONO-7475-sensitive cells, and both are classified as megakaryoblastic leukemia (FAB-M7). SiRNA knockdown studies showed that the cell growth in MOLM16 was partially dependent on Mertk (63.5%) but totally dependent on double genes, Axl and Mertk. Furthermore, knockdown of the ligands Gas6 and Pros1 also partially inhibited the cell growth in MOLM16, respectively (46.0%, 49.2%).

Conclusion: Our data suggest that Mertk may play an important role in survival signaling in FLT3-WT AML. Therefore, targeting both Axl and Mertk by ONO-7475 could be a new strategy for the treatment of FLT3-WT patients with AML in addition to FLT3-ITD. Additional work to investigate and clarify for target populations in both FLT3-ITD and -WT AML is currently under way.

Citation Format: Kohei Tanaka, Cuifang Li, Tomomi Hirosaki, Hikaru Kato, Yoshinori Ishikawa, Miho Oka, Hiroshi Egawa, Ryohei Kozaki, Toshio Yoshizawa. A novel Axl and Mertk dual inhibitor ONO-7475: A new therapeutic agent for the treatment of FLT3-ITD and -wild-type acute myeloid leukemia (AML) overexpressing [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1883.

Responses to the Selective Bruton's Tyrosine Kinase (BTK) Inhibitor Tirabrutinib (ONO/GS-4059) in Diffuse Large B-cell Lymphoma Cell Lines

Bruton’s tyrosine kinase (BTK) is a key regulator of the B-cell receptor signaling pathway, and aberrant B-cell receptor (BCR) signaling has been implicated in the survival of malignant B-cells. However, responses of the diffuse large B-cell lymphoma (DLBCL) to inhibitors of BTK (BTKi) are infrequent, highlighting the need to identify mechanisms of resistance to BTKi as well as predictive biomarkers. We investigated the response to the selective BTKi, tirabrutinib, in a panel of 64 hematopoietic cell lines. Notably, only six cell lines were found to be sensitive. Although activated B-cell type DLBCL cells were most sensitive amongst all cell types studied, sensitivity to BTKi did not correlate with the presence of activating mutations in the BCR pathway. To improve efficacy of tirabrutinib, we investigated combination strategies with 43 drugs inhibiting 34 targets in six DLBCL cell lines. Based on the results, an activated B-cell-like (ABC)-DLBCL cell line, TMD8, was the most sensitive cell line to those combinations, as well as tirabrutinib monotherapy. Furthermore, tirabrutinib in combination with idelalisib, palbociclib, or trametinib was more effective in TMD8 with acquired resistance to tirabrutinib than in the parental cells. These targeted agents might be usefully combined with tirabrutinib in the treatment of ABC-DLBCL.

Abstract 3727: Plasma inhibitory activity (PIA) is a possible pharmacodynamic marker for clinical development of a next generation pan-TRK inhibitor, ONO-5390556

Background: Colorectal cancer and Mammary analogue secretory carcinoma harboring Neurotrophic tyrosine receptor kinase (NTRK/TRK) gene rearrangements developed resistance to Entrectinib, ALK/ROS/TRK inhibitor. We previously demonstrated that the next generation pan-TRK inhibitor,ONO-5390556 may potently overcome Entrectinib-resistance mutations. Furthermore, inhibition of Trk phosphorylation in tumors has excellent correlation with the in vivo anti-tumor effect by ONO-5390556 (AACR2016, Kozaki et al). Purpose: Accurate measurement of target inhibition in a phase 1 clinical trial is critical to informing selection of appropriate doses for ONO-5390556 in more advanced clinical trials. Plasma inhibitory activity (PIA) assay has recently been performed as a surrogate assay in clinical trials of FLT3, MET and ALK kinase inhibitors. The assay employs the incubation of Tyrosine Kinase expressing cell lines in aliquots of plasma collected at various time points from patients treated with TKI. Herein, we report the preclinical evaluation of PIA assay in accordance with an inhibition of TRK phosphorylation in tumors. Methods: KM12 cells, human colorectal cancer cell lines expressing TPM3-TRKA, were implanted subcutaneously into nude mice. Mice were randomized when the mean tumor volume was 150-600 mm3. Tumors and blood were collected from mice, 2, 4, 7 and 24 hours after the single treatment of ONO-5390556 with the doses of 0.06 and 0.6 mg/kg. The collected tumors were disrupted and phosphorylated TrkA in tumors was detected by Electrochemiluminescence (ECL). In a PIA assay, KM12 was incubated in plasma from the collected blood for 4 hours and phosphorylated TrkA in the cells was detected by ECL.. Results: Treatment with ONO-5390556 at doses of 0.06, 0.6 mg/kg resulted in a significant inhibition of Trk phosphorylation in tumors up to 24 hours. Compared to inhibition of P-TRK in tumors, the inhibition of P-TRK in PIA sustained until 7 hours but rapidly decreased at 24 hours after administration. The levels of both tumors and PIA showed in a dose-dependent inhibition and an excellent correlation until 7 hours. Inhibition of TRK phosphorylation (PIA/Tumor, %)0.06 mg/kg (2,4,7,24h) : 56.3/41.4 (PIA/Tumor, %), 51.9/53.5, 43.0/66.5, -5.5/51.30.6 mg/kg (2,4,7,24h) : 90.2/84.3, 88.4/93.0, 87.4/95.7, 8.3/83.3Conclusion: We have validated the PIA assay that correlates with the inhibition of P-TRK in tumors. Our results demonstrated that the potential utility of PIA as a PD marker may contribute to determining the effective dose of ONO-5390556 in the clinical development.

Citation Format: Ryohei Kozaki, Ryu Fujikawa, Hikaru Kato, Natsuka Goto, Toshio Yoshizawa. Plasma inhibitory activity (PIA) is a possible pharmacodynamic marker for clinical development of a next generation pan-TRK inhibitor, ONO-5390556 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3727. doi:10.1158/1538-7445.AM2017-3727

Anti-tumor efficacy study of the Bruton's tyrosine kinase (BTK) inhibitor, ONO/GS-4059, in combination with the glycoengineered type II anti-CD20 monoclonal antibody obinutuzumab (GA101) demonstrates superior in vivo efficacy compared to ONO/GS-4059 in combination with rituximab

The activated B-cell diffuse large B-cell-like lymphoma (ABC-DLBCL) correlates with poor prognosis. The B-cell receptor signaling pathway is known to be dysregulated in NHL/CLL and given BTK is a downstream mediator of BCR signaling, BTK constitutes an interesting and obvious therapeutic target. Given the high potency and selectivity of the BTK inhibitor, ONO/GS-4059, it was hypothesized that, the anti-tumor activity of ONO/GS-4059 could be further enhanced by combining it with the anti-CD20 Abs, rituximab (RTX) or obinutuzumab (GA101). ONO/GS-4059 combined with GA101 or RTX was significantly better than the respective monotherapy with tumor growth inhibition (TGI) of 90% for the GA101 combination and 86% for the RTX combination. In contrast, ibrutinib (PCI-32765) combined with RTX did not result in improved efficacy compared with respective monotherapy. Taken together these data indicate that the combination of ONO/GS-4059 with rituximab and particularly obinutuzumab may be an effective treatment for ABC-DLBCL.

Abstract 2954A: A potent and selective TRK inhibitor ONO-5390556, shows potent antitumor activity against both TRK-rearranged cancers and the resistant mutants

Purpose: TRKA/NTRK1, TRKB/NTRK2 and TRKC/NTRK3 belong to the neurotrophic tyrosine kinase receptor family and signals from TRK receptors play a role in neuronal survival and differentiation through activation of MAPK and AKT downstream pathways. Recently, oncogenic rearrangements of TRKA, B and C gene were identified in a variety of cancers, including lung adenocarcinoma, colorectal cancer, glioblastoma and acute myeloid leukemia. These genomic rearrangements resulted in sustained cancer cell proliferation. Recent studies indicate that targeting TRK by Entrectinib, pan-TRK, ALK and ROS1 inhibitor, may be effective in the treatment of cancers with TRK rearrangements. However, patients treated with Entrectinib showed resistance early due to NTRK1 harboring acquired mutations, G595R and G667C. ONO-5390556 is a selective pan-TRK inhibitor and shows highly potent anti-tumor activity against TRK rearranged cancers. We evaluated the anti-tumor activity of ONO-5390556 against NTRK1 rearranged cancer cells with harboring mutated G595R and G667C.

Methods: The anti-tumor activity of ONO-5390556 was evaluated in subcutaneous xenograft tumor models of KM12, human colorectal cancer cell lines expressing TPM3-TRKA. ONO-5390556 was administered orally with doses ranging between 0.2 and 2 mg/kg once a day for 14 days. In

vitro cytotoxic activity, cell viability was evaluated by WST-8 in TPM3-TRKA positive cells harboring mutated G595R and G667C. Phosphorylated proteins were detected by Western blotting.

Results: In KM12 xenograft model, treatment with ONO-5390556 at doses of 0.2, 0.6, 2 mg/kg once a day resulted in a dose-dependent inhibition of tumor growth with Tumor Growth Inhibition (TGI) of 44.4, 86.6 and 95.4%, respectively. Both G595R and G667C mutations conferred resistance to Entrectinib, but were sensitive to ONO-5390556 with an IC50 of 2.7 and 0.2 nmol/L, respectively. Interestingly, the inhibitory activity of ONO-5390556 sustained in these mutations compared with wild type (IC50 of 0.4 nmol/L). ONO-5390556 strongly inhibited phosphorylation of the TRKA mutated. Additionally, Erk phosphorylation remained strongly inhibited in KM12 cells harboring mutated G595R.

Conclusion: The oncogenic TRK fusion proteins are attractive therapeutic targets but two mutations acquired resistance has been found in the clinic. ONO-5390556 is a highly potent and selective pan-TRK inhibitor with evidence of an excellent anti-tumor activity not only in cancer cells harboring the TRKA rearrangement but also in the two acquired mutations. These results suggest that ONO-5390556 may overcome Entrectinib-resistance mutations and become a potential role for sequential therapy with first generation TRK inhibitors.

Citation Format: Ryohei Kozaki, Toshio Yoshizawa, Kohki Tsukamoto, Hikaru Kato, Kazuhito Kawabata. A potent and selective TRK inhibitor ONO-5390556, shows potent antitumor activity against both TRK-rearranged cancers and the resistant mutants. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2954A.

Abstract 788: A novel, potent and selective pan-Trk inhibitor ONO-5390556, demonstrates therapeutic efficacy in cancer cells harboring the TrkA rearrangement

Purpose: Fusion genes including EML4-ALK, which have been recognized as driver mutations in cancers, encode chimeric proteins with constitutive kinase activity, which promote tumor cell survival. Patients with ALK-Positive Non-Small Cell Lung Cancer have demonstrated remarkable clinical responses to the ALK tyrosine kinase inhibitor, Crizotinib. TrkA/NTRK1,TrkB/NTRK2 and TrkC/NTRK3 belong to the neurotrophic tyrosine kinase receptor family. Signals from Trk receptors play a role in neuronal survival and differentiation through several signal cascades. Recently, oncogenic rearrangements of TrkA, B and C genes were identified in a variety of cancers, including lung adenocarcinoma, colorectal cancer, glioblastoma and acute myeloid leukemia. Therefore, the oncogenic Trk fusion proteins are attractive therapeutic targets that warrant further investigation. ONO-5390556 is a novel, potent and selective pan-Trk inhibitor with an IC50 in the low nM range. We evaluated the anti-tumor activity of ONO-5390556 against TrkA rearranged cancer cells in vitro and in vivo.

Methods: Phospho-proteins were detected by Western blotting. In a proliferation assay, cells were treated with ONO-5390556 at concentrations ranging from 0.03 to 100 nM for 72h. Cell viability was determined by WST-8 assay. In a KM12 xenograft model, cells were implanted subcutaneously into female nude mice. Mice were randomized when the mean tumor volume was 100-200 mm3. ONO-5390556 was administered orally with doses ranging between 0.1 and 1 mg/kg twice daily (BD) for 14 days. Tumor volumes were measured twice a week after initiation of treatment, and tumor volumes were determined using the formula volume ( = width2 x length)/2.

Results: ONO-5390556 inhibited TrkA autophosphorylation and cell proliferation in BaF3 murine pro B cell lines transformed with a TrkA fusion gene with an IC50 of 0.4 and 0.2 nM, respectively. Similarly, in KM12, human colorectal cancer cell lines harboring TPM3-TrkA fusions, both the autophosphorylation of TrkA and the cell proliferation were strongly inhibited by ONO-5390556 with an IC50 of 0.2 and 0.3 nM, respectively. Interestingly, TrkA autophosphorylation remained strongly inhibited even 24 hours after a washout of ONO-5390556 in KM12, which suggests ONO-5390556 has tight-binding properties. In the KM12 Xenograft model, treatment with ONO-5390556 at doses of 0.1, 0.3 and 1mg (BD) for 14 days resulted in a dose-dependent inhibition of tumor growth with Tumor Growth Inhibition (TGI) of 48.0, 89.2 and 95.6%, respectively.

Conclusion: ONO-5390556 is a highly potent and selective pan-Trk inhibitor with evidence of an excellent anti-tumor activity in cancer cells harboring the TrkA rearrangement. These preliminary results suggest that ONO-5390556 may be an effective therapeutic option in a wide variety of cancers including lung and colorectal cancers with Trk rearrangements.

Citation Format: Kohki Tsukamoto, Toshio Yoshizawa, Ryohei Kozaki, Kazuhito Kawabata. A novel, potent and selective pan-Trk inhibitor ONO-5390556, demonstrates therapeutic efficacy in cancer cells harboring the TrkA rearrangement. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 788. doi:10.1158/1538-7445.AM2015-788

Efficacy and immunomodulatory actions of ONO-4641, a novel selective agonist for sphingosine 1-phosphate receptors 1 and 5, in preclinical models of multiple sclerosis

ONO-4641 is a next-generation sphingosine 1-phosphate (S1P) receptor agonist selective for S1P receptors 1 and 5. The objective of the study was to characterize the immunomodulatory effects of ONO-4641 using preclinical data. ONO-4641 was tested in both in-vitro pharmacological studies as well as in-vivo models of transient or relapsing-remitting experimental autoimmune encephalomyelitis (EAE). In vitro, ONO-4641 showed highly potent agonistic activities versus S1P receptors 1 and 5 [half maximal effective concentration (EC(50) ) values of 0·0273 and 0·334 nM, respectively], and had profound S1P receptor 1 down-regulating effects on the cell membrane. ONO-4641 decreased peripheral blood lymphocyte counts in rats by inhibiting lymphocyte egress from secondary lymphoid tissues. In a rat experimental autoimmune encephalomyelitis (EAE) model, ONO-4641 suppressed the onset of disease and inhibited lymphocyte infiltration into the spinal cord in a dose-dependent manner at doses of 0·03 and 0·1 mg/kg. Furthermore, ONO-4641 prevented relapse of disease in a non-obese diabetic mouse model of relapsing-remitting EAE. These observations suggest that ONO-4641 may provide therapeutic benefits in the treatment of multiple sclerosis.

Serum-deprivation induces cell death of rat cultured microglia accompanied with expression of Bax protein

Expression of Bcl-2 related proteins in rat microglial primary culture was examined. At relative low cell densities, serum deprivation caused cell death and nuclei condensation of cultured microglia. Expression of a pro-apoptotic protein, Bax, but not Bcl-2, was increased by the serum deprivation. SB203580, a specific inhibitor of p38MAPK, prevented both the serum deprivation-induced Bax expression and microglial death. Immunochemical staining showed that microglia expressing a high level of Bax were subjected to apoptosis-like cell death. These observations suggest that Bax expression underlies the apoptosis of cultured microglia after serum deprivation.

[Twenty-year follow-up of visual field defects in primary glaucoma eyes]

PURPOSE

The time course of visual field defects in patients with primary glaucoma was investigated for 20 or more years.

METHODS

The subjects were 51 eyes of 29 patients (open angle glaucoma, 40 eyes of 21 patients angle closure glaucoma, 11 eyes of 8 patients). The mean intraocular pressure of these subjects was within 21 mmHg during the follow-up periods. All the eyes were monitored with Goldmann's perimetry, and the visual field was graded using Kozaki's classification.

RESULTS

At the 20-year follow-up, 68% of the open angle cases and 45% of the angle closure cases had significant progression of visual field defects. There was no significant difference in average intraocular pressure during the follow-up period between the progression group and the stable group.

CONCLUSION

These results suggested that, in a follow-up of twenty years, visual field defects both in primary open angle glaucoma and chronic angle closure glaucoma can progress frequently, even if the intraocular pressure of these patients was well controlled.