Exposure-efficacy relationship of vedolizumab subcutaneous and intravenous formulations in Crohn's disease and ulcerative colitis.

BACKGROUND AND AIMS: This posthoc analysis of the GEMINI and VISIBLE studies in ulcerative colitis (UC) and Crohn's Disease (CD) assessed exposure-efficacy of vedolizumab intravenous (IV) and subcutaneous (SC). METHODS: A previously described population pharmacokinetic model was used to predict average serum and trough concentrations at steady state (Cav,ss, Ctrough,ss) and simulate the transition from vedolizumab IV to SC. Efficacy was defined as clinical remission at week 52: complete Mayo score ≤ 2 points and no individual subscore > 1 point (UC), and CD activity index score ≤ 150 points (CD). RESULTS: Data were from 1968 patients (GEMINI 1 [n = 334], VISIBLE 1 [n = 216], GEMINI 2 [n = 1009], VISIBLE 2 [n = 409]) who received maintenance treatment with vedolizumab IV-Q8W, IV-Q4W, SC-Q2W, or placebo. Model-predicted Cav,ss for IV-Q8W and SC-Q2W was similar in UC and CD. Cav,ss was higher for IV-Q4W than IV-Q8W and SC-Q2W. Ctrough,ss values from IV and SC aligned well with pooled observed Ctrough by treatment group in UC and CD. Cav,ss was equivalent for SC and IV. For UC and CD, efficacy rates were greater in patients in the highest quartiles of vedolizumab exposure for both formulations. CONCLUSION: Exposure-efficacy relationships for IV and SC vedolizumab administration were comparable, confirming that both are equally effective during maintenance treatment.

Efficacy of vedolizumab during intravenous induction therapy in ulcerative colitis and Crohn's disease: post hoc analysis of patient-reported outcomes from the VISIBLE 1 and 2 studies.

BACKGROUND: Vedolizumab is an anti-α4ß7 integrin antibody used to treat moderate to severe ulcerative colitis (UC) and Crohn's disease (CD). This post hoc analysis of patient-reported outcomes (PROs) from the VISIBLE 1 (NCT02611830) and 2 (NCT02611817) phase 3 studies evaluated onset of treatment effect on patient-reported symptoms during 6-week vedolizumab induction. METHODS: Patient-reported stool frequency (SF) and rectal bleeding (RB) (UC Mayo score), and SF and abdominal pain (AP) in CD were collected via electronic diary from VISIBLE patients receiving one or more open-label intravenous (IV) vedolizumab induction doses (weeks 0 and 2). PRO data were analyzed using descriptive statistics. RESULTS: Data from 994 patients (UC 383, CD 611) showed mean ratings for all PROs declined consistently week-on-week from baseline through week 6, with early onset of improvement. By week 2, 22% of patients with UC reported RB improvement (≥1-point reduction in RB subscore, 7-day mean), rising to 45% by week 6. By week 6, 18% of patients with UC achieved SF improvement (SF subscore 0; 21% antitumor necrosis factor alpha [anti-TNFα] naive, 13% anti-TNFα experienced). SF improvement in patients with CD (reduction of ≥3 stools, 7-day mean) was achieved by 32% at week 6 (34% anti-TNFα naive, 30% anti-TNFα experienced). Fewer patients with CD reported severe/moderate AP at week 6 (5.1%/28.5%) than baseline (14.6%/61.5%). SF decline appeared greater and faster for anti-TNFα-naive vs. anti-TNFα-experienced patients (UC and CD). CONCLUSION: Results indicate early onset of patient-reported UC and CD symptom improvement during vedolizumab IV induction in VISIBLE 1 and 2.

Practical Primer Addressing Real-World Use Scenarios of Subcutaneous Vedolizumab in Ulcerative Colitis and Crohn's Disease: Post Hoc Analyses of VISIBLE Studies.

Background: Vedolizumab, an anti-α4ß7 integrin approved for intravenous (IV) treatment of moderately to severely active ulcerative colitis (UC) and Crohn's disease (CD), was evaluated as a subcutaneous (SC) formulation in maintenance therapy for UC and CD in phase 3 VISIBLE 1, 2, and open-label extension studies, and recently approved in Europe, Australia, and Canada. Our aim was to evaluate efficacy and safety of IV and SC vedolizumab in clinically relevant UC and CD scenarios. Methods: Post hoc data analyses from VISIBLE trials examined: (1) whether baseline characteristics predict clinical response to 2 vs 3 IV vedolizumab induction doses; (2) efficacy and safety of switching during maintenance vedolizumab IV to SC in patients with UC; (3) vedolizumab SC after treatment interruption of 1-46 weeks; (4) increasing dose frequency of vedolizumab SC from every 2 weeks (Q2W) to every week (QW) after disease worsening. Results: No baseline characteristics were identified as strong predictors of response to 2 vs 3 vedolizumab infusions. Most patients achieved clinical response after 2 or 3 doses of IV vedolizumab maintained with SC treatment. Clinical remission and response rates were maintained in patients transitioned from maintenance vedolizumab IV to SC treatment. Of patients with UC, ≥75% achieved response following resumption after dose interruption. Escalation to QW dosing resulted in ≥45% of patients regaining response after loss while receiving vedolizumab Q2W. Conclusions: Clinical real-world scenarios with vedolizumab SC were reviewed using VISIBLE studies data. Vedolizumab SC provides an additional dosing option for patients with UC and CD.

Using supervised machine learning approach to predict treatment outcomes of vedolizumab in ulcerative colitis patients.

With recent advances in machine learning, we demonstrated the use of supervised machine learning to optimize the prediction of treatment outcomes of vedolizumab through iterative optimization using VARSITY and VISIBLE 1 data in patients with moderate-to-severe ulcerative colitis. The analysis was carried out using elastic net regularized regression following a 2-stage training process. The model performance was assessed through AUROC, specificity, sensitivity, and accuracy. The generalizable predictive patterns suggest that easily obtained baseline and medical history variables may be able to predict therapeutic response to vedolizumab with clinically meaningful accuracy, implying a potential for individualized prescription of vedolizumab.

Efficacy and Safety of Subcutaneous Vedolizumab in Patients With Moderately to Severely Active Crohn's Disease: Results From the VISIBLE 2 Randomised Trial.

BACKGROUND AND AIMS: To report results from VISIBLE 2, a randomised, double-blind, placebo-controlled, phase 3 trial evaluating a new subcutaneous [SC] vedolizumab formulation as maintenance treatment in adults with moderately to severely active Crohn's disease [CD]. METHODS: Following open-label vedolizumab 300 mg intravenous induction therapy at Weeks 0 and 2, Week 6 clinical responders (≥70-point decrease in CD Activity Index [CDAI] score from baseline) were randomised 2:1 to receive double-blind maintenance vedolizumab 108 mg SC or placebo every 2 weeks until Week 50. Assessments at Week 52 included clinical remission [primary endpoint; CDAI ≤150], enhanced clinical response [≥100-point decrease in CDAI from baseline], corticosteroid-free clinical remission among patients using a corticosteroid at baseline, clinical remission in anti-tumour necrosis factor [anti-TNF]-naïve patients, and safety. RESULTS: Following vedolizumab intravenous induction, 275 patients were randomised to vedolizumab SC and 135 to placebo maintenance. At Week 52, 48.0% of patients receiving vedolizumab SC versus 34.3% receiving placebo were in clinical remission [p = 0.008]. Enhanced clinical response at Week 52 was achieved by 52.0% versus 44.8% of patients receiving vedolizumab SC versus placebo, respectively [p = 0.167]. At Week 52, 45.3% and 18.2% of patients receiving vedolizumab SC and placebo, respectively, were in corticosteroid-free clinical remission, and 48.6% of anti-TNF-naïve patients receiving vedolizumab SC and 42.9% receiving placebo were in clinical remission. Injection site reaction was the only new safety finding observed for vedolizumab SC [2.9%]. CONCLUSIONS: Vedolizumab SC is an effective and safe maintenance therapy in patients with CD who responded to two infusions of vedolizumab intravenous induction therapy.

A hybrid approach of handling missing data under different missing data mechanisms: VISIBLE 1 and VARSITY trials for ulcerative colitis.

Missing data is common in clinical trials. Depending on the volume and nature of missing data, it may reduce statistical power for detecting treatment difference, introduce potential bias and invalidate conclusions. Non-responder imputation (NRI), where patients with missing information to determine endpoint status are considered as treatment failures, is widely used to handle missing data for dichotomous efficacy endpoints in inflammatory bowel disease (IBD) trials. However, it does not consider the mechanisms leading to missing data and can potentially underestimate the treatment effect. We proposed a hybrid imputation approach combining NRI and multiple imputation (MI) as an alternative to NRI to assess the impact of dropouts for different missing data mechanisms (categorized as "missing not at random [MNAR]" and "missing at random [MAR]"). Two phase 3 vedolizumab clinical trials under different study designs in patients with moderate-to-severe ulcerative colitis (UC), VISIBLE 1 and VARSITY, are presented to illustrate how the proposed hybrid approach can be implemented as a pre-specified sensitivity analysis in practice. The proposed hybrid imputation provided consistent efficacy results with those using NRI, and can serve as a useful pre-specified sensitivity analysis to assess the impact of dropouts under different missing data mechanisms and evaluate the robustness of efficacy conclusions.

Efficacy and Safety of Vedolizumab Subcutaneous Formulation in a Randomized Trial of Patients With Ulcerative Colitis.

BACKGROUND & AIMS: Maintenance treatment with vedolizumab, a monoclonal antibody that inhibits the gut-selective α4ß7 integrin, is administered intravenously. Some patients might prefer a subcutaneous formulation of vedolizumab for maintenance treatment. Subcutaneous vedolizumab was investigated as maintenance treatment in patients with moderately to severely active ulcerative colitis. METHODS: We performed a phase 3, double-blind, double-dummy trial at 141 sites in 29 countries from December 18, 2015 through August 21, 2018. Patients with moderately to severely active ulcerative colitis received open-label treatment with intravenous vedolizumab 300 mg at weeks 0 and 2. At week 6, patients with clinical response were randomly assigned maintenance treatment with subcutaneous vedolizumab 108 mg every 2 weeks, intravenous vedolizumab 300 mg every 8 weeks, or placebo. The primary end point was clinical remission at week 52, which was defined as a total Mayo score of ≤2 and no subscore >1. RESULTS: Among the randomized 216 patients, clinical remission at week 52 was achieved by 46.2%, 42.6%, and 14.3% of patients in the subcutaneous vedolizumab, intravenous vedolizumab, and placebo groups, respectively (subcutaneous vedolizumab vs placebo: Δ32.3%; 95% confidence interval, 19.7%-45.0%; P < .001). The subcutaneous vedolizumab group also had greater endoscopic improvement and durable clinical response at week 52 compared with placebo (both P < .001). The incidence of injection-site reactions was more frequent in patients given subcutaneous vedolizumab (10.4%) than intravenous vedolizumab (1.9%) or placebo (0%); these were not treatment limiting, most were mild, and none resulted in discontinuation. Subcutaneous and intravenous vedolizumab safety profiles were otherwise similar. CONCLUSIONS: Subcutaneous vedolizumab is effective as maintenance therapy in patients with moderately to severely active ulcerative colitis who had a clinical response to intravenous vedolizumab induction therapy. It has a favorable safety and tolerability profile. ClinicalTrials.gov ID: NCT02611830; EudraCT 2015-000480-14.

Efficacy and Safety of Febuxostat Extended and Immediate Release in Patients With Gout and Renal Impairment: A Phase III Placebo-Controlled Study.

OBJECTIVE: To assess the efficacy and safety of febuxostat extended release (XR) and immediate release (IR) in patients with gout and normal or impaired renal function. METHODS: This was a 3-month, phase III, multicenter, double-blind, placebo-controlled study. Patients (n = 1,790) with a history of gout and normal or impaired (mild-to-severe) renal function were randomized to receive placebo, febuxostat IR 40 or 80 mg, or febuxostat XR 40 or 80 mg once daily (1:1:1:1:1 ratio). End points included proportions of patients with a serum urate (UA) level of <5.0 mg/dl at month 3 (primary end point), a serum UA level of <6.0 mg/dl at month 3, and ≥1 gout flare requiring treatment over 3 months (secondary end points). RESULTS: Both febuxostat formulations led to significantly greater proportions of patients achieving a serum UA level of <5.0 mg/dl or <6.0 mg/dl at month 3 (P < 0.001 for all comparisons versus placebo). Equivalent doses of febuxostat XR and IR had similar treatment effects on serum UA level end points; however, a significantly greater proportion of patients achieved a serum UA level of <5.0 mg/dl with XR 40 mg versus IR 40 mg. Similar proportions of patients experienced ≥1 gout flare across treatment groups. Rates of treatment-emergent adverse events were low and evenly distributed between treatment arms. A preplanned subgroup analysis demonstrated that febuxostat formulations were well tolerated and generally effective on serum UA level end points (versus placebo) across all renal function subgroups. CONCLUSION: Both formulations of febuxostat (XR and IR) were well tolerated and effective in patients with gout and normal or impaired renal function, including patients with severe renal impairment.

Metformin inhibits the growth of human pancreatic cancer xenografts.

OBJECTIVE: Pancreatic ductal adenocarcinoma is a devastating disease, with an overall 5-year survival rate of only 3% to 5%. As the current therapies offer very limited survival benefits, novel therapeutic strategies are urgently required to treat this disease. Here, we determined whether metformin administration inhibits the growth of PANC-1 and MiaPaCa-2 tumor xenografts in vivo. METHODS: Different xenograft models, including orthotopic implantation, were used to determine whether intraperitoneal or oral administration of metformin inhibits the growth of pancreatic cancer in vivo. RESULTS: We demonstrate that metformin given once daily intraperitoneally at various doses (50-250 mg/kg) to nude mice inhibited the growth of PANC-1 xenografts in a dose-dependent manner. A significant effect of metformin was obtained at 50 mg/kg and maximal effect at 200 mg/kg. Metformin administration also caused a significant reduction in the phosphorylation of ribosomal S6 protein and ERK in these xenografts. Metformin also inhibited the growth of pancreatic cancer xenografts when administered orally (2.5 mg/mL) either before or after tumor implantation. Importantly, oral administration of metformin also inhibited the growth of MiaPaCa-2 tumors xenografted orthotopically. CONCLUSIONS: The studies presented here provide further evidence indicating that metformin offers a potential novel approach for pancreatic ductal adenocarcinoma prevention and therapy.

Different patterns of Akt and ERK feedback activation in response to rapamycin, active-site mTOR inhibitors and metformin in pancreatic cancer cells.

The mTOR pathway is aberrantly stimulated in many cancer cells, including pancreatic ductal adenocarcinoma (PDAC), and thus it is a potential target for therapy. However, the mTORC1/S6K axis also mediates negative feedback loops that attenuate signaling via insulin/IGF receptor and other tyrosine kinase receptors. Suppression of these feed-back loops unleashes over-activation of upstream pathways that potentially counterbalance the antiproliferative effects of mTOR inhibitors. Here, we demonstrate that treatment of PANC-1 or MiaPaCa-2 pancreatic cancer cells with either rapamycin or active-site mTOR inhibitors suppressed S6K and S6 phosphorylation induced by insulin and the GPCR agonist neurotensin. Rapamycin caused a striking increase in Akt phosphorylation at Ser(473) while the active-site inhibitors of mTOR (KU63794 and PP242) completely abrogated Akt phosphorylation at this site. Conversely, active-site inhibitors of mTOR cause a marked increase in ERK activation whereas rapamycin did not have any stimulatory effect on ERK activation. The results imply that first and second generation of mTOR inhibitors promote over-activation of different pro-oncogenic pathways in PDAC cells, suggesting that suppression of feed-back loops should be a major consideration in the use of these inhibitors for PDAC therapy. In contrast, metformin abolished mTORC1 activation without over-stimulating Akt phosphorylation on Ser(473) and prevented mitogen-stimulated ERK activation in PDAC cells. Metformin induced a more pronounced inhibition of proliferation than either KU63794 or rapamycin while, the active-site mTOR inhibitor was more effective than rapamycin. Thus, the effects of metformin on Akt and ERK activation are strikingly different from allosteric or active-site mTOR inhibitors in PDAC cells, though all these agents potently inhibited the mTORC1/S6K axis.

Metformin inhibition of mTORC1 activation, DNA synthesis and proliferation in pancreatic cancer cells: dependence on glucose concentration and role of AMPK.

Metformin, a widely used anti-diabetic drug, is emerging as a potential anticancer agent but the mechanisms involved remain incompletely understood. Here, we demonstrate that the potency of metformin induced AMPK activation, as shown by the phosphorylation of its substrates acetyl-CoA carboxylase (ACC) at Ser(79) and Raptor at Ser(792), was dramatically enhanced in human pancreatic ductal adenocarcinoma (PDAC) cells PANC-1 and MiaPaCa-2 cultured in medium containing physiological concentrations of glucose (5 mM), as compared with parallel cultures in medium with glucose at 25 mM. In physiological glucose, metformin inhibited mTORC1 activation, DNA synthesis and proliferation of PDAC cells stimulated by crosstalk between G protein-coupled receptors and insulin/IGF signaling systems, at concentrations (0.05-0.1 mM) that were 10-100-fold lower than those used in most previous reports. Using siRNA-mediated knockdown of the α(1) and α(2) catalytic subunits of AMPK, we demonstrated that metformin, at low concentrations, inhibited DNA synthesis through an AMPK-dependent mechanism. Our results emphasize the importance of using medium containing physiological concentrations of glucose to elucidate the anticancer mechanism of action of metformin in pancreatic cancer cells and other cancer cell types.

Crosstalk between insulin/insulin-like growth factor-1 receptors and G protein-coupled receptor signaling systems: a novel target for the antidiabetic drug metformin in pancreatic cancer.

Insulin/insulin-like growth factor 1(IGF-1) receptors and G protein-coupled receptors (GPCR) signaling systems are implicated in autocrine-paracrine stimulation of a variety of malignancies, including ductal adenocarcinoma of the pancreas, one of the most lethal human diseases. Novel targets for pancreatic cancer therapy are urgently needed. We identified a crosstalk between insulin/IGF-1 receptors and GPCR signaling systems in pancreatic cancer cells, leading to enhanced signaling, DNA synthesis, and proliferation. Crosstalk between these signaling systems depends on mammalian target of rapamycin (mTOR) complex 1 (mTORC1). Metformin, the most widely used drug in the treatment of type 2 diabetes, activates AMP kinase (AMPK), which negatively regulates mTORC1. Recent results show that metformin-induced activation of AMPK disrupts crosstalk between insulin/IGF-1 receptor and GPCR signaling in pancreatic cancer cells and inhibits the growth of these cells in xenograft models. Given that insulin/IGF-1 and GPCRs are implicated in other malignancies, a similar crosstalk mechanism may be operative in other cancer cell types. Recent epidemiological studies linked administration of metformin with a reduced risk of pancreatic, breast, and prostate cancer in diabetic patients. We posit that crosstalk between insulin/IGF-1 receptor and GPCR signaling is a mechanism for promoting the development of certain types of cancer and a target for the prevention and therapy of these diseases via metformin administration.

Induced overexpression of protein kinase D1 stimulates mitogenic signaling in human pancreatic carcinoma PANC-1 cells.

Neurotensin (NT) stimulates protein kinase D1 (PKD1), extracellular signal regulated kinase (ERK), c-Jun N-terminal Kinase (JNK), and DNA synthesis in the human pancreatic adenocarcinoma cell line PANC-1. To determine the effect of PKD1 overexpression on these biological responses, we generated inducible stable PANC-1 clones that express wild-type (WT) or kinase-dead (K618N) forms of PKD1 in response to the ecdysone analog ponasterone-A (PonA). NT potently stimulated c-Jun Ser(63) phosphorylation in both wild type and clonal derivatives of PANC-1 cells. PonA-induced expression of WT, but not K618N PKD1, rapidly blocked NT-mediated c-Jun Ser(63) phosphorylation either at the level of or upstream of MKK4, a dual-specificity kinase that leads to JNK activation. This is the first demonstration that PKD1 suppresses NT-induced JNK/cJun activation in PANC-1 cells. In contrast, PKD1 overexpression markedly increased the duration of NT-induced ERK activation in these cells. The reciprocal influence of PKD1 signaling on pro-mitogenicERK and pro-apopotic JNK/c-Jun pathways prompted us to examine whether PKD1 overexpression promotes DNA synthesis and proliferation of PANC-1 cells. Our results show that PKD1 overexpression increased DNA synthesis and cell numbers of PANC-1 cells cultured in regular dishes or in polyhydroxyethylmethacrylate [Poly-(HEMA)]-coated dishes to eliminate cell adhesion (anchorage-independent growth). Furthermore, PKD1 overexpression markedly enhanced DNA synthesis induced by NT (1-10 nM). These results indicate that PKD1 mediates mitogenic signaling in PANC-1 and suggests that this enzyme could be a novel target for the development of therapeutic drugs that restrict the proliferation of these cells.

Metformin disrupts crosstalk between G protein-coupled receptor and insulin receptor signaling systems and inhibits pancreatic cancer growth.

Recently, we identified a novel crosstalk between insulin and G protein-coupled receptor (GPCR) signaling pathways in human pancreatic cancer cells. Insulin enhanced GPCR signaling through a rapamycin-sensitive mTOR-dependent pathway. Metformin, the most widely used drug in the treatment of type 2 diabetes, activates AMP kinase (AMPK), which negatively regulates mTOR. Here, we determined whether metformin disrupts the crosstalk between insulin receptor and GPCR signaling in pancreatic cancer cells. Treatment of human pancreatic cancer cells (PANC-1, MIAPaCa-2, and BxPC-3) with insulin (10 ng/mL) for 5 minutes markedly enhanced the increase in intracellular [Ca(2+)] induced by GPCR agonists (e.g., neurotensin, bradykinin, and angiotensin II). Metformin pretreatment completely abrogated insulin-induced potentiation of Ca(2+) signaling but did not interfere with the effect of GPCR agonists alone. Insulin also enhanced GPCR agonist-induced growth, measured by DNA synthesis, and the number of cells cultured in adherent or nonadherent conditions. Low doses of metformin (0.1-0.5 mmol/L) blocked the stimulation of DNA synthesis, and the anchorage-dependent and anchorage-independent growth induced by insulin and GPCR agonists. Treatment with metformin induced striking and sustained increase in the phosphorylation of AMPK at Thr(172) and a selective AMPK inhibitor (compound C, at 5 micromol/L) reversed the effects of metformin on [Ca(2+)](i) and DNA synthesis, indicating that metformin acts through AMPK activation. In view of these results, we tested whether metformin inhibits pancreatic cancer growth. Administration of metformin significantly decreased the growth of MIAPaCa-2 and PANC-1 cells xenografted on the flank of nude mice. These results raise the possibility that metformin could be a potential candidate in novel treatment strategies for human pancreatic cancer.

Insulin potentiates Ca2+ signaling and phosphatidylinositol 4,5-bisphosphate hydrolysis induced by Gq protein-coupled receptor agonists through an mTOR-dependent pathway.

Multiple lines of evidence support the existence of crosstalk between the insulin receptor and G protein-coupled receptor (GPCR) signaling systems. However, the precise molecular mechanism(s) mediating this interaction is poorly understood. The results presented in this study show that exposure of ductal pancreatic adenocarcinoma BxPc-3, HPAF-II, and PANC-1 cells to insulin for as little as 1 min rapidly enhanced the magnitude and the rate of increase in intracellular Ca2+ concentration produced by the GPCR agonists bradykinin, angiotensin II, vasopressin, neurotensin, and bombesin. The potentiating effect of insulin was dose dependent, and it was produced in response to Gq protein-coupled, but not Gi protein-coupled, receptor agonists. Real-time imaging of single cells showed that treatment with insulin enhances the rate and magnitude of phosphatidylinositol 4,5-bisphosphate hydrolysis and generation of inositol 1,4,5-trisphosphate in response to GPCR stimulation. Short-term treatment with rapamycin, an mTOR (mammalian target of rapamycin) inhibitor, completely abrogated the ability of insulin to increase the rate and magnitude of Ca2+ signaling and production of inositol 1,4,5-trisphosphate in response to bradykinin stimulation, indicating that insulin potentiates Gq protein-coupled receptor signaling through an mTOR-dependent pathway. We propose that the potentiation of GPCR signaling by insulin provides a mechanism by which insulin enhances cellular responsiveness to Gq protein-coupled receptor agonists, including GPCR-mediated autocrine and paracrine loops in cancer cells.

Broad-spectrum G protein-coupled receptor antagonist, [D-Arg1,D-Trp5,7,9,Leu11]SP: a dual inhibitor of growth and angiogenesis in pancreatic cancer.

Substance P analogues, including [D-Arg(1),D-Trp(5,7,9),Leu(11)]SP (SPA) are broad-spectrum G protein-coupled receptor (GPCR) antagonists that have potential antitumorigenic activities, although the mechanism(s) are not completely understood. Here, we examined the effects of SPA in ductal pancreatic cancers that express multiple GPCRs for mitogenic agonists and also produce proangiogenic chemokines. Using HPAF-II, a well-differentiated pancreatic cancer cell line as our model system, we showed that SPA inhibited multiple neuropeptide-induced Ca(2+) mobilization, DNA synthesis, and anchorage-independent growth in vitro. SPA also significantly attenuated the growth of HPAF-II tumor xenografts in nude mice beyond the treatment period. Interestingly, SPA markedly increased apoptosis but moderately decreased proliferation marker, Ki-67 in the tumor xenografts implying additional mechanism(s) for the significant growth inhibitory effect observed in vivo. HPAF-II cells express ELR(+) CXC chemokines, including IL-8/CXCL8, which bind to CXCR2 (a member of GPCR superfamily) and promote angiogenesis in multiple cancers, including pancreatic cancer. SPA inhibited CXCR2-mediated Ca(2+) mobilization and blocked specifically IL-8/CXCL8-induced angiogenesis in rat corneal micropocket assay in vivo. A salient feature of the results presented here is that SPA markedly reduced tumor-associated angiogenesis in the HPAF-II xenografts in vivo. Our results show that SPA, a broad-spectrum GPCR antagonist attenuates tumor growth in pancreatic cancer via a dual mechanism involving both the antiproliferative and antiangiogenic properties. We conclude that this novel dual-inhibitory property of SPA could be of significant therapeutic value in pancreatic cancer, when used in combination with other antiproliferative and/or antiangiogenic agents.

Neurotensin and EGF induce synergistic stimulation of DNA synthesis by increasing the duration of ERK signaling in ductal pancreatic cancer cells.

Neurotensin (NT) and epidermal growth factor (EGF) induced rapid extracellular-regulated protein kinase (ERK) activation through different signaling pathways in the K-Ras mutated human pancreatic carcinoma cell lines PANC-1 and MIA PaCa-2. NT stimulated ERK activation via a protein kinase C (PKC)-dependent (but EGF receptor-independent) pathway in PANC-1 and MIA PaCa-2 cells, whereas EGF promoted ERK activation through a PKC-independent pathway in these cells. Concomitant stimulation of these cells with NT and EGF induced a striking increase in the duration of ERK pathway activation as compared with that obtained in cells treated with each agonist alone. Stimulation with NT + EGF promoted synergistic stimulation of DNA synthesis and anchorage-independent growth. Addition of the MEK inhibitor U0126, either prior to stimulation with NT + EGF or 2 h after stimulation with NT + EGF prevented the synergistic increase in DNA synthesis and suppressed the sustained phase of ERK activation. Furthermore, treatment with the selective PKC inhibitor GF-1 converted the sustained ERK activation in response to NT and EGF into a transient signal and also abrogated the synergistic increase in DNA synthesis. Collectively, our results suggest that the sustained phase of ERK signaling mediates the synergistic effects of NT and EGF on DNA synthesis in pancreatic cancer cells.