Effect of meloxicam or robenacoxib administration timing on renal function and postoperative analgesia in cats undergoing ovariohysterectomy: A randomized, blinded, controlled clinical trial.

We evaluated the effect of administration timing of meloxicam and robenacoxib on renal function, platelet cyclo-oxygenase and perioperative analgesia in 60 cats undergoing ovariohysterectomy, in a prospective randomized blinded controlled study. Twelve cats were randomly allocated to one subcutaneous treatment group: meloxicam (0.2 mg/kg) or robenacoxib (2 mg/kg) at admission (MA, RA), at induction (MI, RI) and robenacoxib at the end of surgery (RE). All cats received the same anaesthesia protocol. Plasma renin activity (PRA), plasma creatinine, drug concentrations and serum thromboxane (TxB2) were measured sequentially. Anaesthesia significantly increased PRA, as activity at end of the surgery was higher than 2 h later (mean ± SD: 26.6 ± 2.8 versus 10.0 ± 3.9 ng/mL/h). PRA remained higher at 2 h post-surgery in admission groups compared to induction groups (p = .01). Serum TxB2 was lower with meloxicam than robenacoxib (p = .001), and was lower in the MA than each robenacoxib group at catheter placement. Admission groups (16/24 from RA and MA groups) received earlier rescue analgesia than other groups (p = .033). In conclusion, the renin-angiotensin system was activated during anaesthesia despite cyclo-oxygenase inhibition, possibly due to hypotension or surgical stimulation. There was no effect of drug or timing on the markers of renal function but one cat receiving meloxicam at induction had suspected IRIS grade II acute kidney injury.

Serum C-reactive protein and iron levels following gonadectomy are not modified by perioperative administration of robenacoxib to dogs.

The aim of this study was to evaluate the perioperative effects of robenacoxib on serum C-reactive protein (CRP) and iron concentrations in dogs undergoing gonadectomy. In a prospective, blinded, controlled clinical trial, 60 healthy dogs were randomly assigned to receive preoperative subcutaneous injection of either robenacoxib [2 mg/kg body weight (BW)], meloxicam (0.2 mg/kg BW), or saline (0.04 mL/kg BW), followed by oral administration over 72 h (robenacoxib: 2 to 4 mg/kg BW; meloxicam: 0.1 mg/kg BW; saline: gelatin capsules). Blood samples were taken before surgery and 12, 24, 48, 72 h, and 7 d after surgery. Pain scores were assessed via the short-form Glasgow Composite Pain Scale over 72 h postoperatively. C-reactive protein (CRP) and iron serum levels increased and decreased (P < 0.01, both), respectively, after surgery and returned to baseline within 1 wk. No differences were observed among treatments (P > 0.05) or based on surgery/gender (P > 0.05). Pain assessment revealed a higher incidence of treatment failure in saline (6 females versus 2 and 1 female in robenacoxib and meloxicam, respectively). In conclusion, robenacoxib and meloxicam had no influence on postoperative CRP or iron in dogs, which suggests that these nonsteroidal anti-inflammatory drugs (NSAIDs) do not have a relevant effect on these biomarkers.

Le but de cette étude était d'évaluer les effets périopératoires du robenacoxib sur les concentrations sériques de protéine C réactive (CRP) et de fer chez des chiens subissant une gonadectomie. Dans un essai clinique prospectif, en aveugle et contrôlé, 60 chiens en bonne santé ont été randomisés pour recevoir une injection sous-cutanée préopératoire de robenacoxib [2 mg/kg de poids corporel (PC)], de méloxicam (0,2 mg/kg de poids corporel) ou de solution saline (0,04 mL/kg de poids corporel), suivie d'une administration orale pendant 72 h (robenacoxib : 2 à 4 mg/kg de poids corporel; méloxicam : 0,1 mg/kg de poids corporel; saline : gélules). Des échantillons de sang ont été prélevés avant la chirurgie et 12, 24, 48, 72 h et 7 jours après la chirurgie. Les pointages de douleur ont été évalués via l'échelle abrégée Glasgow Composite Pain Scale sur 72 h après l'opération. Les taux sériques de CRP et de fer ont augmenté et diminué (P < 0,01, les deux), respectivement, après la chirurgie et sont revenus à la valeur de base en 1 semaine. Aucune différence n'a été observée entre les traitements (P > 0,05) ou en fonction de la chirurgie/du sexe (P > 0,05). L'évaluation de la douleur a révélé une incidence plus élevée d'échec du traitement avec la saline (6 femelles contre 2 et 1 femelles pour le robenacoxib et le méloxicam, respectivement). En conclusion, le robenacoxib et le méloxicam n'ont eu aucune influence sur la CRP ou le fer postopératoire chez le chien, ce qui suggère que ces anti-inflammatoires non stéroïdiens (AINS) n'ont pas d'effet pertinent sur ces biomarqueurs.(Traduit par Docteur Serge Messier).

Phase 1 study of the pan-HER inhibitor dacomitinib plus the MEK1/2 inhibitor PD-0325901 in patients with KRAS-mutation-positive colorectal, non-small-cell lung and pancreatic cancer.

BACKGROUND: Mutations in KRAS result in a constitutively activated MAPK pathway. In KRAS-mutant tumours existing treatment options, e.g. MEK inhibition, have limited efficacy due to resistance through feedback activation of epidermal growth factor receptors (HER). METHODS: In this Phase 1 study, the pan-HER inhibitor dacomitinib was combined with the MEK1/2 inhibitor PD-0325901 in patients with KRAS-mutant colorectal, pancreatic and non-small-cell lung cancer (NSCLC). Patients received escalating oral doses of once daily dacomitinib and twice daily PD-0325901 to determine the recommended Phase 2 dose (RP2D). (Clinicaltrials.gov: NCT02039336). RESULTS: Eight out of 41 evaluable patients (27 colorectal cancer, 11 NSCLC and 3 pancreatic cancer) among 8 dose levels experienced dose-limiting toxicities. The RP2D with continuous dacomitinib dosing was 15 mg of dacomitinib plus 6 mg of PD-0325901 (21 days on/7 days off), but major toxicity, including rash (85%), diarrhoea (88%) and nausea (63%), precluded long-term treatment. Therefore, other intermittent schedules were explored, which only slightly improved toxicity. Tumour regression was seen in eight patients with the longest treatment duration (median 102 days) in NSCLC. CONCLUSIONS: Although preliminary signs of antitumour activity in NSCLC were seen, we do not recommend further exploration of this combination in KRAS-mutant patients due to its negative safety profile.

Triple blockade of EGFR, MEK and PD-L1 has antitumor activity in colorectal cancer models with constitutive activation of MAPK signaling and PD-L1 overexpression.

BACKGROUND: Molecular mechanisms driving acquired resistance to anti-EGFR therapies in metastatic colorectal cancer (mCRC) are complex but generally involve the activation of the downstream RAS-RAF-MEK-MAPK pathway. Nevertheless, even if inhibition of EGFR and MEK could be a strategy for overcoming anti-EGFR resistance, its use is limited by the development of MEK inhibitor (MEKi) resistance. METHODS: We have generated in vitro and in vivo different CRC models in order to underline the mechanisms of MEKi resistance. RESULTS: The three different in vitro MEKi resistant models, two generated by human CRC cells quadruple wild type for KRAS, NRAS, BRAF, PI3KCA genes (SW48-MR and LIM1215-MR) and one by human CRC cells harboring KRAS mutation (HCT116-MR) showed features related to the gene signature of colorectal cancer CMS4 with up-regulation of immune pathway as confirmed by microarray and western blot analysis. In particular, the MEKi phenotype was associated with the loss of epithelial features and acquisition of mesenchymal markers and morphology. The change in morphology was accompanied by up-regulation of PD-L1 expression and activation of EGFR and its downstream pathway, independently to RAS mutation status. To extend these in vitro findings, we have obtained mouse colon cancer MC38- and CT26-MEKi resistant syngeneic models (MC38-MR and CT26-MR). Combined treatment with MEKi, EGFR inhibitor (EGFRi) and PD-L1 inhibitor (PD-L1i) resulted in a marked inhibition of tumor growth in both models. CONCLUSIONS: These results suggest a strategy to potentially improve the efficacy of MEK inhibition by co-treatment with EGFR and PD-L1 inhibitors via modulation of host immune responses.

Potentiated anti-tumor effects of BETi by MEKi in anaplastic thyroid cancer.

Anaplastic thyroid cancer (ATC) is an aggressive malignancy with limited treatment options. We explored novel treatment modalities by targeting epigenetic modifications using inhibitors of BET (e.g. BRD4) activity. We evaluated the efficacy in the treatment of ATC of a novel BET inhibitor, PLX51107 (PLX), currently in clinical trials for other solid tumors and hematologic malignancies, alone or combined with a MEK inhibitor, PD0325901(PD). To elucidate the effects of these inhibitors on growth of ATC, we treated ATC cells derived from patient tumors (THJ-11T and THJ-16T cells) and mouse xenograft tumors with inhibitors. We found PLX and PD inhibitors singly inhibited proliferation of both human ATC cells lines, but together exhibited stronger inhibition of proliferation. In mouse xenografts, the combination treatment almost totally blocked growth in xenograft tumors derived from both ATC cells. PD effectively attenuated MEK-ERK signaling, which was further enhanced by PLX in the combined treatment in cultured cells and tumors. Importantly, the combination of PLX and PD acted synergistically to suppress MYC transcription to increase p27 in decreasing tumor cell proliferation. PLX and PD cooperated to upregulate pro-apoptotic proteins to promote apoptosis. These two inhibitors converged to reduce the binding of BRD4 to the MYC promoter to suppress the MYC expression. These findings indicate that combined treatment of BET and MEK-ERK inhibitors was more effective to treat ATC than single targeted treatment. Synergistic suppression of MYC transcription via collaborative actions on chromatin modifications suggested that targeting epigenetic modifications could provide novel treatment opportunities for ATC.

Sorafenib/MEK inhibitor combination inhibits tumor growth and the Wnt/ß­catenin pathway in xenograft models of hepatocellular carcinoma.

Mutations affecting the Wnt/ß­catenin pathway have been identified in 26­40% of hepatocellular carcinoma (HCC) cases. Aberrant activation of this pathway leads to uncontrolled cell proliferation and survival. Thus, identifying Wnt/ß­catenin pathway inhibitors may benefit a subset of patients with HCC. In the present study, the effects of sorafenib and a MEK inhibitor on tumor growth and Wnt/ß­catenin signaling in HCC models were evaluated. A ß­catenin mutant and ß­catenin wild­type HCC models were treated once daily with i) 10 mg/kg sorafenib, ii) 15 mg/kg refametinib (or 25 mg/kg selumetinib), or iii) sorafenib/refametinib. Western blotting was employed to determine changes in biomarkers relevant to Wnt/ß­catenin signaling. Apoptosis, cell proliferation and ß­catenin localization were analyzed by immunohistochemistry. Sorafenib/refametinib markedly inhibited tumor growth and cell proliferation, and caused cell death in naïve and sorafenib­resistant HCC models. Despite similar total ß­catenin levels, significant reductions in phosphorylated (p)­RanBP3 Ser58, p­ß­catenin Tyr142, active ß­catenin and ß­catenin target genes were observed in sorafenib/refametinib­treated tumors. Greater levels of ß­catenin in sorafenib/refametinib­treated tumors were accumulated at the membrane, as compared with in the control. In vitro, sorafenib/refametinib inhibited the Wnt/ß­catenin pathway and suppressed Wnt­3A­induced p­low­density lipoprotein receptor­related protein 6 Ser1490, p­RanBP3 Ser58 and p­ß­catenin Tyr142 in HCC cells. Combination of sorafenib and refametinib inhibits the growth of naïve and sorafenib resistant HCC tumors in association with active suppression of ß­catenin signaling regardless of ß­catenin mutational status. Thus, the sorafenib/MEK inhibitor combination may represent an alternative treatment for patients with HCC whose tumors develop resistance to sorafenib therapy.

ERK1/2-dependent gene expression in the bovine ovulating follicle.

Ovulation is triggered by gonadotropin surge-induced signaling cascades. To study the role of extracellular signal-regulated kinase 1/2 (ERK1/2) in bovine ovulation, we administered the pharmacological inhibitor, PD0325901, into the preovulatory dominant follicle by intrafollicular injection. Four of five cows treated with 50 µM PD0325901 failed to ovulate. To uncover the molecular basis of anovulation in ERK1/2-inhibited cows, we collected granulosa and theca cells from Vehicle and PD0325901 treated follicles. Next-generation sequencing of granulosa cell RNA revealed 285 differentially expressed genes between Vehicle and PD0325901-treated granulosa cells at 6 h post-GnRH. Multiple inflammation-related pathways were enriched among the differentially expressed genes. The ERK1/2 dependent LH-induced genes in granulosa cells included EGR1, ADAMTS1, STAT3 and TNFAIP6. Surprisingly, PD0325901 treatment did not affect STAR expression in granulosa cells at 6 h post-GnRH. Granulosa cells had higher STAR protein and theca cells had higher levels of STAR mRNA in ERK1/2-inhibited follicles. Further, both granulosa and theca cells of ERK1/2-inhibited follicles had higher expression of SLC16A1, a monocarboxylate transporter, transporting substances including ß-hydroxybutyrate across the plasma membrane. Taken together, ERK1/2 plays a significant role in mediating LH surge-induced gene expression in granulosa and theca cells of the ovulating follicle in cattle.

Phase II Studies with Refametinib or Refametinib plus Sorafenib in Patients with RAS-Mutated Hepatocellular Carcinoma.

Purpose: Refametinib, an oral MEK inhibitor, has demonstrated antitumor activity in combination with sorafenib in patients with RAS-mutated hepatocellular carcinoma (HCC). Two phase II studies evaluated the efficacy of refametinib monotherapy and refametinib plus sorafenib in patients with RAS-mutant unresectable or metastatic HCC.Patients and Methods: Eligible patients with RAS mutations of cell-free circulating tumor DNA (ctDNA) determined by beads, emulsion, amplification, and magnetics technology received twice-daily refametinib 50 mg ± sorafenib 400 mg. Potential biomarkers were assessed in ctDNA via next-generation sequencing (NGS).Results: Of 1,318 patients screened, 59 (4.4%) had a RAS mutation, of whom 16 received refametinib and 16 received refametinib plus sorafenib. With refametinib monotherapy, the objective response rate (ORR) was 0%, the disease control rate (DCR) was 56.3%, overall survival (OS) was 5.8 months, and progression-free survival (PFS) was 1.9 months. With refametinib plus sorafenib, the ORR was 6.3%, the DCR was 43.8%, OS was 12.7 months, and PFS was 1.5 months. In both studies, time to progression was 2.8 months. Treatment-emergent toxicities included fatigue, hypertension, and acneiform rash. Twenty-seven patients had ctDNA samples available for NGS. The most frequently detected mutations were in TERT (63.0%), TP53 (48.1%), and ß-catenin (CTNNB1; 37.0%).Conclusions: Prospective testing for RAS family mutations using ctDNA was a feasible, noninvasive approach for large-scale mutational testing in patients with HCC. A median OS of 12.7 months with refametinib plus sorafenib in this small population of RAS-mutant patients may indicate a synergistic effect between sorafenib and refametinib-this preliminary finding should be further explored. Clin Cancer Res; 24(19); 4650-61. ©2018 AACR.

Adaptation to TKI Treatment Reactivates ERK Signaling in Tyrosine Kinase-Driven Leukemias and Other Malignancies.

FMS-like tyrosine kinase-3 (FLT3) tyrosine kinase inhibitors (TKI) have been tested extensively to limited benefit in acute myeloid leukemia (AML). We hypothesized that FLT3/internal tandem duplication (ITD) leukemia cells exhibit mechanisms of intrinsic signaling adaptation to TKI treatment that are associated with an incomplete response. Here, we identified reactivation of ERK signaling within hours following treatment of FLT3/ITD AML cells with selective inhibitors of FLT3. When these cells were treated with inhibitors of both FLT3 and MEK in combination, ERK reactivation was abrogated and anti-leukemia effects were more pronounced compared with either drug alone. ERK reactivation was also observed following inhibition of other tyrosine kinase-driven cancer cells, including EGFR-mutant lung cancer, HER2-amplified breast cancer, and BCR-ABL leukemia. These studies reveal an adaptive feedback mechanism in tyrosine kinase-driven cancers associated with reactivation of ERK signaling in response to targeted inhibition. Cancer Res; 77(20); 5554-63. ©2017 AACR.

Efficacy and safety of oral robenacoxib (tablet) for the treatment of pain associated with soft tissue surgery in client-owned dogs.

BACKGROUND: Non-steroidal anti-inflammatory drugs (NSAIDs) have been proven to be effective in controlling peri-operative pain in dogs. Robenacoxib is an NSAID with high selectivity for the cyclooxygenase (COX)-2 isoform. The objective of this study was to assess the efficacy and safety of an oral tablet formulation of robenacoxib in client-owned dogs undergoing soft tissue surgery. The study was a prospective, multi-center, randomized, masked, placebo-controlled, parallel-group clinical trial. A total of 239 dogs were included and randomly allocated in a 1:1 ratio to receive either robenacoxib or placebo. Each dog received an oral tablet administration of either robenacoxib, at a target dose of 2 mg/kg, or placebo once prior to surgery and for two additional days post-operatively. All dogs also received a pre-anesthetic dose of 0.2 mg/kg butorphanol (intravenous or intramuscular). Pain assessments were performed using the short form of the Glasgow Composite Measure Pain Scale. Robenacoxib was compared to the placebo group on a success/failure basis. Treatment failure was defined as the need for rescue therapy to control post-operative pain. RESULTS: Significantly (P = 0.019) more dogs administered robenacoxib were considered treatment successes (89 of 116, 76.72%) compared to dogs given placebo (74 of 115, 64.35%). The percentage of treatment failure was therefore 23.28% in the robenacoxib and 35.65% in the placebo group. The least squares mean total pain scores were significantly different between groups and in favor of robenacoxib at 3 and 5 hours (P < 0.05) and 8 hours post-extubation (P < 0.01). Pain at the surgery sites (response to touch) was also significantly improved at 3, 5 and 8 hours post-extubation in dogs receiving robenacoxib versus placebo (P < 0.01). In addition, a significant overall improvement in posture/activity was revealed with robenacoxib having lower scores versus placebo (P < 0.01). No significant differences between the robenacoxib and placebo groups in the frequency of reported adverse events were observed. CONCLUSIONS: Robenacoxib by oral (tablet) administration was effective and well tolerated in the control of peri-operative pain and inflammation associated with soft tissue surgery in dogs.

Efficacy and Safety of Injectable Robenacoxib for the Treatment of Pain Associated With Soft Tissue Surgery in Dogs.

BACKGROUND: Nonsteroidal anti-inflammatory drugs (NSAIDs) are used routinely to control pain and inflammation after surgery in dogs. Robenacoxib is a cyclooxygenase-2 selective NSAID. HYPOTHESIS/OBJECTIVE: Assess the clinical efficacy and safety of an injectable formulation of robenacoxib in dogs undergoing surgery. ANIMALS: Three hundred and seventeen client-owned dogs (N = 159 robenacoxib or N = 158 placebo). METHODS: In this prospective, multicenter, randomized, masked, placebo-controlled, parallel-group study, dogs received a SC injection of either robenacoxib, at a target dose of 2.0 mg/kg, or placebo once prior to surgery and for 2 additional days postoperatively. Pain assessments were performed using the short form of the Glasgow Composite Measure Pain Scale (CMPS-SF). The primary efficacy variable was treatment success/failure, with failure defined as the need for rescue therapy to control pain or withdrawal of the dog from the study due to an adverse event. RESULTS: Significantly (P = .006) more dogs administered robenacoxib were considered treatment successes (108 of 151, 73.7%) compared to dogs given placebo (85 of 152, 58.1%). Total pain scores (P < .01), pain at the surgery sites (response to touch, P < .01), and posture/activity (P < .05) were significantly improved at 3, 5, and 8 hours postextubation in dogs receiving robenacoxib versus placebo. CONCLUSIONS AND CLINICAL IMPORTANCE: Robenacoxib administered by SC injection prior to surgery and for 2 additional days postoperatively was effective and well tolerated in the control of postoperative pain and inflammation associated with soft tissue surgery in dogs.

Combined BRAFV600E and MEK blockade for BRAFV600E-mutant gliomas.

BRAFV600E is a common finding in glioma (about 10-60% depending on histopathologic subclassification). BRAFV600E monotherapy shows modest preclinical efficacy against BRAFV600E gliomas and also induces adverse secondary skin malignancies. Here, we examine the molecular mechanism of intrinsic resistance to BRAFV600E inhibition in glioma. Furthermore, we investigate BRAFV600E/MEK combination therapy that overcomes intrinsic resistance to BRAFV600E inhibitor and also prevents BRAFV600E inhibitor induced secondary malignancies. Immunoblotting and Human Phospho-Receptor Tyrosine Kinase Array assays were used to interrogate MAPK pathway activation. The cellular effect of BRAFV600E and MEK inhibition was determined by WST-1 viability assay and cell cycle analysis. Flanked and orthotopic GBM mouse models were used to investigate the in vivo efficacy of BRAFV600E/MEK combination therapy and the effect on secondary malignancies. BRAFV600E inhibition leads to recovery of ERK phosphorylation. Combined BRAFV600E and MEK inhibition prevents reactivation of the MAPK signaling, which correlates with decreased cell viability and augmented cell cycle arrest. Similarly, mice bearing BRAFV600E glioma showed reduced tumor growth when treated with a combination of BRAFV600E and MEK inhibitor compared to BRAFV600E inhibition alone. Additional benefit of BRAFV600E/MEK inhibition was reflected by reduced cutaneous squamous-cell carcinoma (cSCC) growth (a surrogate for RAS-driven secondary maligancies). In glioma, recovery of MAPK signaling upon BRAF inhibition accounts for intrinsic resistance to BRAFV600E inhibitor. Combined BRAFV600E and MEK inhibition prevents rebound of MAPK activation, resulting in enhanced antitumor efficacy and also reduces the risk of secondary malignancy development.

CK2 blockade causes MPNST cell apoptosis and promotes degradation of ß-catenin.

Malignant peripheral nerve sheath tumors (MPNSTs) are soft tissue sarcomas that are a major cause of mortality of Neurofibromatosis type 1 (NF1) patients. MPNST patients have few therapeutic options available and only complete surgical resection can be curative. MPNST formation and survival are dependent on activated ß-catenin signaling. The goal of this study was to determine if inhibition of the CK2 enzyme can be therapeutically exploited in MPNSTs, given CK2's role in mainta ining oncogenic phenotypes including stabilization of ß-catenin. We found that CK2α is over-expressed in MPNSTs and is critical for maintaining cell survival, as the CK2 inhibitor, CX-4945 (Silmitasertib), and shRNA targeting CK2α each significantly reduce MPNST cell viability. These effects were preceded by loss of critical signaling pathways in MPNSTs, including destabilization of ß-catenin and TCF8. CX-4945 administration in vivo slowed tumor growth and extends survival time. We conclude that CK2 inhibition is a promising approach to blocking ß-catenin in MPNST cells, although combinatorial therapies may be required for maximal efficacy.

ADAM17-siRNA inhibits MCF-7 breast cancer through EGFR-PI3K-AKT activation.

A disintegrin and metalloproteinase-17 (ADAM17) can cut and release a wide variety of epidermal growth factor receptor (EGFR) ligands to promote survival, invasion and proliferation of cancer cell, and therefore, is considered to be a potential therapeutic target for cancer. The main goal of the present study was to observe the effects of ADAM17 small interfering RNA (ADAM17-siRNA) on human MCF-7 breast cancer and investigate its activation pathway. In vitro, MCF-7 cells were divided into ADAM17-siRNA groups, nonsense siRNA groups, AG1478 (selective EGFR blocker) groups, LY294002 [phosphatidylinositol 3-kinase (PI3K) phosphorylation inhibitor] groups, PD0325901 [mitogen extracellular kinase (MEK) inhibitor] groups and control groups. In vivo, MCF-7 cells were implanted subcutaneously into nude mice and then these mice were randomly divided into ADAM17-siRNA groups, vector groups and control groups. Our data showed that compared with the control groups, ADAM17-siRNA, AG1478 and LY294002 could inhibit the migration and proliferation of MCF-7 cells, but PD0325901 and nonsense siRNA did not show this effect. Except that specific ADAM17-siRNA could inhibit the expression of ADAM17 mRNA, others did not change it. Western blot analysis further confirmed that EGFR-PI3K-AKT signaling pathway is involved in ADAM17-siRNA inhibiting migration and proliferation of MCF-7 cells. Similarly to the former, the growth of MCF-7 breast cancer in nude mice was significantly inhibited by ADAM17-siRNA. Compared with the control group and the vector group, the tumor volume was smaller in the ADAM17-siRNA group, the tissues developed large areas of necrosis, immunohistochemistry showed low expressions of ADAM17 and Ki-67 and western blot analysis proved that the expression of ADAM17 protein in the tissue was also reduced. The present study suggests that ADAM17-siRNA inhibits MCF-7 breast cancer and is activated through the EGFR-PI3K-AKT signaling pathway.

RGD peptide conjugation results in enhanced antitumor activity of PD0325901 against glioblastoma by both tumor-targeting delivery and combination therapy.

Glioblastoma (GBM) is the most aggressive tumor type in the central nervous system. Both tumor-targeting drug delivery and combination therapy of multiple therapeutic agents with distinct mechanisms are important for GBM treatment. We combined these two strategies and developed a new platform of peptide-drug conjugate (RGD-PEG-Suc-PD0325901, W22) for tumor-targeting delivery using a combination of PD0325901 (a MEK1/2 inhibitor) and RGD peptide. In the present study, the combination of PD0325901 and RGD peptide strongly inhibited U87MG model in vitro and in vivo. This inhibition contributed to synergistic suppression of cell proliferation by blocking ERK pathway activity and cell migration. Modified by conjugation strategy, their conjugate W22 enhanced PD0325901 delivery to GBM cells by receptor mediated cellular internalization. W22 showed great superiority in targeting to U87MG xenografted tumors and strong anti-tumor efficacy based on ERK pathway inhibition and tumor-targeted delivery in vitro and in vivo. Moreover, W22 was stable in serum and able to release PD0325901 in the enzymatic environment. These data indicated that the RGD-PEG-Suc-PD0325901 conjugate provided a strategy for effective delivery of PD0325901 and RGD peptide into the GBM cells and inhibition of tumor growth in a synergistic manner.

Maintenance Treatment with Cetuximab and BAY86-9766 Increases Antitumor Efficacy of Irinotecan plus Cetuximab in Human Colorectal Cancer Xenograft Models.

PURPOSE: The use of cetuximab in the treatment of metastatic colorectal cancer is limited by development of resistance. EXPERIMENTAL DESIGN: We have investigated in three models of highly epidermal growth factor receptor (EGFR)-dependent colorectal cancer xenografts, the effect of maintenance therapy with different kinase inhibitors alone or in combination with cetuximab, after cytotoxic treatment induction with irinotecan plus cetuximab. RESULTS: SW48, LIM 1215, and GEO colorectal cancer cell lines were engrafted into nude mice and treated for 3 weeks with irinotecan and/or cetuximab. The combined treatment induced a significant reduction of tumor size. A subsequent experiment was performed in all three xenograft models in which after an induction treatment with irinotecan plus cetuximab, mice were randomly assigned to one of the following treatments: control, cetuximab, regorafenib, a selective PIK3CA inhibitor (PIK3CAi), a selective MEK inhibitor (MEKi), and/or the combination of each inhibitor with cetuximab. The cetuximab plus MEKi treatment determined the best antitumor activity with suppression of tumor growth. This effect was prolonged for 13 to 15 weeks after cessation of therapy and was accompanied by prolonged survival. Antitumor activity was accompanied by inhibition of the MAPK and MEK pathways. Moreover, in the cetuximab plus MEKi-treated SW48 xenograft group, KRAS mutations as a mechanism of acquired resistance were detected in 25% of cases compared with 75% KRAS mutations in the MEKi-treated group. CONCLUSIONS: A possible strategy to prevent and/or overcome resistance to anti-EGFR inhibitors in metastatic colorectal cancer is a maintenance therapy with cetuximab plus MEKi after an initial treatment with irinotecan plus cetuximab.

Combined inhibition of MEK and mTOR has a synergic effect on angiosarcoma tumorgrafts.

Angiosarcoma (AS) is a rare neoplasm of endothelial origin that has limited treatment options and poor five-year survival. Using tumorgraft models, we previously showed that AS is sensitive to small-molecule inhibitors that target mitogen-activated/extracellular-signal-regulated protein kinase kinases 1 and 2 (MEK). The objective of this study was to identify drugs that combine with MEK inhibitors to more effectively inhibit AS growth. We examined the in vitro synergy between the MEK inhibitor PD0325901 and inhibitors of eleven common cancer pathways in melanoma cell lines and canine angiosarcoma cell isolates. Combination indices were calculated using the Chou-Talalay method. Optimized combination therapies were evaluated in vivo for toxicity and efficacy using canine angiosarcoma tumorgrafts. Among the drugs we tested, rapamycin stood out because it showed strong synergy with PD0325901 at nanomolar concentrations. We observed that angiosarcomas are insensitive to mTOR inhibition. However, treatment with nanomolar levels of mTOR inhibitor renders these cells as sensitive to MEK inhibition as a melanoma cell line with mutant BRAF. Similar results were observed in B-Raf wild-type melanoma cells as well as in vivo, where treatment of canine AS tumorgrafts with MEK and mTOR inhibitors was more effective than monotherapy. Our data show that a low dose of an mTOR inhibitor can dramatically enhance angiosarcoma and melanoma response to MEK inhibition, potentially widening the field of applications for MEK-targeted therapy.

PKC/MEK inhibitors suppress oxaliplatin-induced neuropathy and potentiate the antitumor effects.

Oxaliplatin is a key drug commonly used in colorectal cancer treatment. Despite high clinical efficacy, its therapeutic application is limited by common, dose-limiting occurrence of neuropathy. As usual symptomatic neuropathy treatments fail to improve the patients' condition, there is an urgent need to advance our understanding of the pathogenesis of neuropathy to propose effective therapy and ensure adequate pain management. Oxaliplatin-induced neuropathy was recently reported to be associated with protein kinase C (PKC) activation. It is unclear, however, whether PKC inhibition can prevent neuropathy. In our current studies, we found that a PKC inhibitor, tamoxifen, inhibited oxaliplatin-induced neuropathy via the PKC/extracellular signal-regulated kinase (ERK)/c-Fos pathway in lumbar spinal cords (lumbar segments 4-6). Additionally, tamoxifen was shown to act in synergy with oxaliplatin to inhibit growth in tumor cells-implanted mice. Moreover, mitogen-activated protein kinase kinase (MEK) 1/2 inhibitor, PD0325901, suppressed oxaliplatin-induced neuropathy and enhanced oxaliplatin efficacy. Our results indicate that oxaliplatin-induced neuropathy is associated with PKC/ERK/c-Fos pathway in lumbar spinal cord. Additionally, we demonstrate that disruption of this pathway by PKC and MEK inhibitors suppresses oxaliplatin-induced neuropathy, thereby suggesting that PKC and MEK inhibitors may be therapeutically useful in preventing oxaliplatin-induced neuropathy and could aid in combination antitumor pharmacotherapy.

A phase II study of the efficacy and safety of the combination therapy of the MEK inhibitor refametinib (BAY 86-9766) plus sorafenib for Asian patients with unresectable hepatocellular carcinoma.

PURPOSE: There is an unmet need for treatment options in hepatocellular carcinoma (HCC). Sorafenib is currently the only approved systemic treatment for HCC. Refametinib, an oral, allosteric MEK inhibitor, has demonstrated antitumor activity in combination with sorafenib in vitro and in vivo. A phase II study evaluated efficacy and safety of refametinib plus sorafenib in Asian patients with HCC (NCT01204177). EXPERIMENTAL DESIGN: Eligible patients received twice-daily refametinib 50 mg plus twice-daily sorafenib 200 mg (morning)/400 mg (evening), with dose escalation to sorafenib 400 mg twice daily from cycle 2 if no grade ≥ 2 hand-foot skin reaction, fatigue, or gastrointestinal toxicity occurred. Primary efficacy endpoint: disease control rate. Secondary endpoints: time to progression, overall survival, pharmacokinetic assessment, biomarker analysis, safety, and tolerability. RESULTS: Of 95 enrolled patients, 70 received study treatment. Most patients had liver cirrhosis (82.9%) and hepatitis B viral infection (75.7%). Disease control rate was 44.8% (primary efficacy analysis; n = 58). Median time to progression was 122 days, median overall survival was 290 days (n = 70). Best clinical responders had RAS mutations; majority of poor responders had wild-type RAS. Most frequent drug-related adverse events were diarrhea, rash, aspartate aminotransferase elevation, vomiting, and nausea. Dose modifications due to adverse events were necessary in almost all patients. CONCLUSIONS: Refametinib plus sorafenib showed antitumor activity in patients with HCC and was tolerated at reduced doses by most patients. Frequent dose modifications due to grade 3 adverse events may have contributed to limited treatment effect. Patients with RAS mutations appear to benefit from refametinib/sorafenib combination.

Pharmacological suppression of the Ras/MAPK pathway in thyroid carcinoma cells can provoke opposite effects on cell migration and proliferation: The appearance of yin-yang effects and the need of combinatorial treatments.

A major challenge in tumor therapy is the decrease or even the halting of cell proliferation and migration of cancerous cells. In the present study, we have analyzed the impact of a pharmacological blockade of the PI3K/Akt and MAPK/ERK1/2 signaling pathways on cell migration, proliferation and cell death in three human thyroid tumor cell lines that represent the main types of malignant thyroid carcinomas (B-CPAP, follicular; Cal-62, anaplastic; FTC-133, papillary thyroid carcinoma cells) and in which these pathways are constitutively activated. In general, pharmacological perturbation of PI3/Akt (application of MK-2206) and MEK/ERK1/2 (application of PD0325901 or U0126) signaling led to a cell line and drug-specific decrease in the proliferation and migration potential of thyroid carcinoma cells, although to a varying extent. However, one exception became apparent: in Cal-62 cells inhibition of the MEK/ERK1/2 module increased the migration rate up to 50%. This effect could be prevented by a simultaneous suppression of the PI3/Akt pathway, but also by application of the multiple kinase inhibitor sorafenib, a treatment that did not change the activation state of Akt. Thus, a pharmacological perturbation of canonical signaling pathways in thyroid carcinoma may induce drug-dependent yin-yang effects that are characterized by a simultaneous suppression of one (i.e., proliferation) and the activation of another (i.e., migration) cellular process. The appearance of such phenomena should be taken into account when therapy plans are established.