Nonspecific oral medications versus anti-calcitonin gene-related peptide monoclonal antibodies for migraine: A systematic review and meta-analysis of randomized controlled trials.

OBJECTIVE: To compare calcitonin gene-related peptide monoclonal antibodies (CGRP mAbs) versus nonspecific oral migraine preventives (NOEPs). BACKGROUND: Insurers mandate step therapy with NOEPs before approving CGRP mAbs. METHODS: Databases were searched for class I or II randomized controlled trials (RCTs) comparing CGRP mAbs or NOEPs versus placebo for migraine prevention in adults. The primary outcome measure was monthly migraine days (MMD) or moderate to severe headache days. RESULTS: Twelve RCTs for CGRP mAbs, 5 RCTs for topiramate, and 3 RCTs for divalproex were included in the meta-analysis. There was high certainty that CGRP mAbs are more effective than placebo, with weighted mean difference (WMD; 95% confidence interval) of -1.64 (-1.99 to -1.28) MMD, which is compatible with small effect size (Cohen's d -0.25 [-0.34 to -0.16]). Certainty of evidence that topiramate or divalproex is more effective than placebo was very low and low, respectively (WMD -1.45 [-1.52 to -1.38] and -1.65 [-2.30 to -1.00], respectively; Cohen's d -1.25 [-2.47 to -0.03] and -0.48 [-0.67 to -0.29], respectively). Trial sequential analysis showed that information size was adequate and that CGRP mAbs had clear benefit versus placebo. Network meta-analysis showed no statistically significant difference between CGRP mAbs and topiramate (WMD -0.19 [-0.56 to 0.17]) or divalproex (0.01 [-0.73 to 0.75]). No significant difference was seen between topiramate or divalproex (0.21 [-0.45 to 0.86]). CONCLUSIONS: There is high certainty that CGRP mAbs are more effective than placebo, but the effect size is small. When feasible, CGRP mAbs may be prescribed as first-line preventives; topiramate or divalproex could be as effective but are less well tolerated. The findings of this study support the recently published 2024 position of the American Headache Society on the use of CGRP mAbs as the first-line treatment.

Myofibrillogenesis Regulator-1 Regulates the Ubiquitin Lysosomal Pathway of Notch3 Intracellular Domain Through E3 Ubiquitin-Protein Ligase Itchy Homolog in the Metastasis of Non-Small Cell Lung Cancer.

Myofibrillogenesis regulator-1 (MR-1) is a multifunctional protein involved in the development of various human tumors. The study is the first to report the promoting effect of MR-1 on the development and metastasis of non-small cell lung cancer (NSCLC). MR-1 is upregulated in NSCLC and positively associated with poor prognosis. The overexpression of MR-1 promotes the metastasis of NSCLC cells by stabilizing the expression of Notch3-ICD (NICD3) in the cytoplasm through enrichment analysis, in vitro and in vivo experimental researches. And Notch3 signaling can upregulate many genes related to metastasis. The stabilizing effect of MR-1 on NICD3 is achieved through the mono-ubiquitin lysosomal pathway and the specific E3 ubiquitin ligase is Itchy homolog (ITCH). There is a certain interaction between MR-1 and NICD3. Elevated MR-1 can affect the level of ITCH phosphorylation, reduce its E3 enzyme activity, and thus lead to reduce the ubiquitination and degradation of NICD3. Interference with the interaction between MR-1 and NICD3 can increase the degradation of NICD3 and impair the metastatic ability of NSCLC cells, which is a previously overlooked treatment option in NSCLC. In summary, interference with the interaction between MR-1 and NICD3 in the progression of lung cancer may be a promising therapeutic target.

Lipidation and PEGylation Strategies to Prolong the in Vivo Half-Life of a Nanomolar EphA4 Receptor Antagonist.

The EphA4 receptor tyrosine kinase plays a role in neurodegenerative diseases, inhibition of nerve regeneration, cancer progression and other diseases. Therefore, EphA4 inhibition has potential therapeutic value. Selective EphA4 kinase inhibitors are not available, but we identified peptide antagonists that inhibit ephrin ligand binding to EphA4 with high specificity. One of these peptides is the cyclic APY-d3 (ßAPYCVYRßASWSC-NH2), which inhibits ephrin-A5 ligand binding to EphA4 with low nanomolar binding affinity and is highly protease resistant. Here we describe modifications of APY-d3 that yield two different key derivatives with greatly increased half-lives in the mouse circulation, the lipidated APY-d3-laur8 and the PEGylated APY-d3-PEG4. These two derivatives inhibit ligand induced EphA4 activation in cells with sub-micromolar potency. Since they retain high potency and specificity for EphA4, lipidated and PEGylated APY-d3 derivatives represent new tools for discriminating EphA4 activities in vivo and for preclinical testing of EphA4 inhibition in animal disease models.

Discovery of a potent GIPR peptide antagonist that is effective in rodent and human systems.

OBJECTIVE: Glucose-dependent insulinotropic polypeptide (GIP) is one of the two major incretin factors that regulate metabolic homeostasis. Genetic ablation of its receptor (GIPR) in mice confers protection against diet-induced obesity (DIO), while GIPR neutralizing antibodies produce additive weight reduction when combined with GLP-1R agonists in preclinical models and clinical trials. Conversely, GIPR agonists have been shown to promote weight loss in rodents, while dual GLP-1R/GIPR agonists have proven superior to GLP-1R monoagonists for weight reduction in clinical trials. We sought to develop a long-acting, specific GIPR peptide antagonist as a tool compound suitable for investigating GIPR pharmacology in both rodent and human systems. METHODS: We report a structure-activity relationship of GIPR peptide antagonists based on the human and mouse GIP sequences with fatty acid-based protraction. We assessed these compounds in vitro, in vivo in DIO mice, and ex vivo in islets from human donors. RESULTS: We report the discovery of a GIP(5-31) palmitoylated analogue, [Nα-Ac, L14, R18, E21] hGIP(5-31)-K11 (γE-C16), which potently inhibits in vitro GIP-mediated cAMP generation at both the hGIPR and mGIPR. In vivo, this peptide effectively blocks GIP-mediated reductions in glycemia in response to exogenous and endogenous GIP and displays a circulating pharmacokinetic profile amenable for once-daily dosing in rodents. Co-administration with the GLP-1R agonist semaglutide and this GIPR peptide antagonist potentiates weight loss compared to semaglutide alone. Finally, this antagonist inhibits GIP- but not GLP-1-stimulated insulin secretion in intact human islets. CONCLUSIONS: Our work demonstrates the discovery of a potent, specific, and long-acting GIPR peptide antagonist that effectively blocks GIP action in vitro, ex vivo in human islets, and in vivo in mice while producing additive weight-loss when combined with a GLP-1R agonist in DIO mice.

The effect of helix-inducing constraints and downsizing upon a transcription block survival-derived functional cJun antagonist.

Inhibition of cJun is established as a promising therapeutic approach, particularly in cancer. We recently developed the "transcription block survival" (TBS) screening platform to derive functional peptide antagonists of transcription factor activity by ablating their ability to bind to cognate DNA. Using TBS, we screened a >131,000-member peptide library to select a 63-mer peptide that bound cJun and prevented 12-O-tetradecanoylphorbol-13-acetate response element (TRE) DNA binding. Iterative truncation was next combined with a systematic exploration of side-chain cyclization to derive a minimal active sequence. The resulting dual lactamized sequence was >40% smaller and retained low nM target affinity (equilibrium binding constant [K D ] = 0.2 versus 9.7 nM), with 8 residues at the acidic region required for functional antagonism. However, even modest C-terminal truncation resulted in functional loss. The peptide functionally antagonizes cJun (half-maximal inhibitory concentration [IC50] = 13 versus 45 µM) and is considerably more stable in human serum relative to its non-lactamized counterpart and HingeW.

Small-molecule non-peptide antagonists of the PACAP receptor attenuate acute restraint stress-induced anxiety-like behaviors in mice.

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a highly conserved pleiotropic neuropeptide, implicated in emotional stress responses and anxiety-related disorders. Here, we examined whether our recently developed small-molecule non-peptide PACAP receptor antagonists could ameliorate anxiety-like behaviors induced by acute restraint stress in mice. The antagonists PA-9 and its derivative PA-915 improved anxiety-like behaviors in mice subjected to restraint stress. An anxiolytic effect was observed with single acute dose, suggesting their fast-acting properties. PA-915 demonstrated a statistically significant anxiolytic effect whereas fluoxetine did not. These results indicate the potential of PAC1 antagonists as a novel treatment for anxiety.

Preclinical and first-in-human evaluation of 18F-labeled D-peptide antagonist for PD-L1 status imaging with PET.

PURPOSE: PD-L1 PET imaging allows for the whole body measuring its expression across primary and metastatic tumors and visualizing its spatiotemporal dynamics before, during, and after treatment. In this study, we reported a novel 18F-labeled D-peptide antagonist, 18F-NOTA-NF12, for PET imaging of PD-L1 status in preclinical and first-in-human studies. METHODS: Manual and automatic radiosynthesis of 18F-NOTA-NF12 was performed. Cell uptake and binding assays were completed in MC38, H1975, and A549 cell lines. The capacity for imaging of PD-L1 status, biodistribution, and pharmacokinetics were investigated in preclinical models. The PD-L1 status was verified by western blotting, immunohistochemistry/fluorescence, and flow cytometry. The safety, radiation dosimetry, biodistribution, and PD-L1 imaging potential were evaluated in healthy volunteers and patients. RESULTS: The radiosynthesis of 18F-NOTA-NF12 was achieved via manual and automatic methods with radiochemical yields of 41.7 ± 10.2 % and 70.6 ± 4.2 %, respectively. In vitro binding assays demonstrated high specificity and affinity with an IC50 of 78.35 nM and KD of 85.08 nM. The MC38 and H1975 tumors were clearly visualized with the optimized tumor-to-muscle ratios of 5.36 ± 1.17 and 7.13 ± 1.78 at 60 min after injection. Gemcitabine- and selumetinib-induced modulation of PD-L1 dynamics was monitored by 18F-NOTA-NF12. The tumor uptake correlated well with their PD-L1 expression. 18F-NOTA-NF12 exhibited renal excretion and rapid clearance from blood and other non-specific organs, contributing to high contrast imaging in the clinical time frame. In NSCLC and esophageal cancer patients, the specificity of 18F-NOTA-NF12 for PD-L1 imaging was confirmed. The 18F-NOTA-NF12 PET/CT and 18F-FDG PET/CT had equivalent findings in patients with high PD-L1 expression. CONCLUSION: 18F-NOTA-NF12 was developed successfully as a PD-L1-specific tracer with promising results in preclinical and first-in-human trials, which support the further validation of 18F-NOTA-NF12 for PET imaging of PD-L1 status in clinical settings.

Copper-67-Labeled Bombesin Peptide for Targeted Radionuclide Therapy of Prostate Cancer.

The gastrin-releasing peptide receptor (GRPR) is a promising molecular target for imaging and therapy of prostate cancer using bombesin peptides that bind to the receptor with high affinity. Targeted copper theranostics (TCTs) using copper radionuclides, 64Cu for imaging and 67Cu for therapy, offer significant advantages in the development of next-generation theranostics. [64Cu]Cu-SAR-BBN is in clinical development for PET imaging of GRPR-expressing cancers. This study explores the therapeutic efficacy of [67Cu]Cu-SAR-BBN in a pre-clinical mouse model. The peptide was radiolabeled with 67Cu, and specific binding of the radiolabeled peptide towards GRPR-positive PC-3 prostate cancer cells was confirmed with 52.2 ± 1.4% total bound compared to 5.8 ± 0.1% with blocking. A therapy study with [67Cu]Cu-SAR-BBN was conducted in mice bearing PC-3 tumors by injecting 24 MBq doses a total of six times. Tumor growth was inhibited by 93.3% compared to the control group on day 19, and median survival increased from 34.5 days for the control group to greater than 54 days for the treatment group. The ease and stability of the radiochemistry, favorable biodistribution, and the positive tumor inhibition demonstrate the suitability of this copper-based theranostic agent for clinical assessment in the treatment of cancers expressing GRPR.

Preclinical and exploratory human studies of novel 68Ga-labeled D-peptide antagonist for PET imaging of TIGIT expression in cancers.

PURPOSE: While TIGIT has been propelled as a next-generation target in cancer immunotherapy, anti-TIGIT therapy seems to be promising for a fraction of patients in clinical trials. Therefore, patient stratification is critical for this therapy, which could benefit from a whole-body, non-invasive, and quantitative evaluation of TIGIT expression in cancers. In this study, a 68Ga-labeled D-peptide antagonist, 68Ga-GP12, was developed and validated for PET imaging of TIGIT expression in vitro, in vivo, and in an exploratory human study. METHODS: The D-enantiomer peptide antagonists were modified and radiolabeled with 68Ga. In vitro binding assays were performed in human peripheral blood mononuclear cells (PBMCs) to assess their affinity and specificity. The imaging capacity, biodistribution, pharmacokinetics, and radiation dosimetry were investigated. Flow cytometry, autoradiography, and immunohistochemical staining were used to confirm the expression of TIGIT. The safety and potential of 68Ga-GP12 for PET/CT imaging of TIGIT expression were evaluated in NSCLC patients. RESULTS: 68Ga-labeled D-peptides were conveniently produced with high radiochemical yields, radiochemical purities and molar activities. In vitro binding assays demonstrated 68Ga-GP12 has high affinity and specificity for TIGIT with a KD of 37.28 nM. In vivo and ex vivo studies demonstrated the capacity of 68Ga-GP12 for PET imaging of TIGIT expression with high tumor uptake of 4.22 ± 0.68 %ID/g and the tumor-to-muscle ratio of 12.94 ± 2.64 at 60 min post-injection. In NSCLC patients, primary and metastatic lesions found in 68Ga-GP12 PET images were comparable to that in 18F-FDG PET images. Moreover, tracer uptake in primary and metastatic lesions and intra-tumoral distribution in the large tumor were inhomogenous, indicating the heterogeneity of TIGIT expression. CONCLUSION: 68Ga-GP12 is a promising radiotracer for PET imaging of TIGIT expression in cancers, indicating its potential as a potential companion diagnostic for anti-TIGIT therapies.

A novel peptide antagonist of the human growth hormone receptor.

Excess circulating human growth hormone (hGH) in vivo is linked to metabolic and growth disorders such as cancer, diabetes, and acromegaly. Consequently, there is considerable interest in developing antagonists of hGH action. Here, we present the design, synthesis, and characterization of a 16-residue peptide (site 1-binding helix [S1H]) that inhibits hGH-mediated STAT5 phosphorylation in cultured cells. S1H was designed as a direct sequence mimetic of the site 1 mini-helix (residues 36-51) of wild-type hGH and acts by inhibiting the interaction of hGH with the human growth hormone receptor (hGHR). In vitro studies indicated that S1H is stable in human serum and can adopt an α-helix in solution. Our results also show that S1H mitigates phosphorylation of STAT5 in cells co-treated with hGH, reducing intracellular STAT5 phosphorylation levels to those observed in untreated controls. Furthermore, S1H was found to attenuate the activity of the hGHR and the human prolactin receptor, suggesting that this peptide acts as an antagonist of both lactogenic and somatotrophic hGH actions. Finally, we used alanine scanning to determine how discrete amino acids within the S1H sequence contribute to its structural organization and biological activity. We observed a strong correlation between helical propensity and inhibitory effect, indicating that S1H-mediated antagonism of the hGHR is largely dependent on the ability for S1H to adopt an α-helix. Taken together, these results show that S1H not only acts as a novel peptide-based antagonist of the hGHR but can also be applied as a chemical tool to study the molecular nature of hGH-hGHR interactions.

G3BP1 promotes human breast cancer cell proliferation through coordinating with GSK-3ß and stabilizing ß-catenin.

Ras-GTPase activating SH3 domain-binding protein 1 (G3BP1) is a multifunctional binding protein involved in the development of a variety of human cancers. However, the role of G3BP1 in breast cancer progression remains largely unknown. In this study, we report that G3BP1 is upregulated and correlated with poor prognosis in breast cancer. Overexpression of G3BP1 promotes breast cancer cell proliferation by stimulating ß-catenin signaling, which upregulates a number of proliferation-related genes. We further show that G3BP1 improves the stability of ß-catenin by inhibiting its ubiquitin-proteasome degradation rather than affecting the transcription of ß-catenin. Mechanistically, elevated G3BP1 interacts with and inactivates GSK-3ß to suppress ß-catenin phosphorylation and degradation. Disturbing the G3BP1-GSK-3ß interaction accelerates the degradation of ß-catenin, impairing the proliferative capacity of breast cancer cells. Our study demonstrates that the regulatory mechanism of the G3BP1/GSK-3ß/ß-catenin axis may be a potential therapeutic target for breast cancer.

Rimegepant Orally Disintegrating Tablet for Acute Migraine Treatment: A Review.

OBJECTIVE: To review the pharmacology, pharmacokinetics, efficacy, safety, and place in therapy of rimegepant for treatment of migraine. DATA SOURCES: A comprehensive PubMed and Cochrane search (1985 to May 2020) was performed utilizing the keywords rimegepant, Nurtec, orally disintegrating tablet, migraine, migraine headache, migraine disorder, calcitonin gene-related peptide, and calcitonin gene-related peptide antagonist. Additional data were obtained from the references of identified articles, manufacturer's product labeling and website, ClinicalTrials.gov, and governmental sources. STUDY SELECTION AND DATA EXTRACTION: All English-language trials evaluating oral rimegepant were included for this review. DATA SYNTHESIS: Rimegepant orally disintegrating tablet (ODT) is Food and Drug Administration approved for the treatment of migraine. According to data from 3 phase 3 randomized controlled trials, rimegepant has been shown to significantly improve freedom from pain at 2 hours after the dose and freedom from the most bothersome symptom 2 hours postdose. Additional outcomes improved include freedom from photophobia and phonophobia at 2 hours postdose and pain relief 2 hours after the dose. Adverse effects of rimegepant include nausea, urinary tract infection, and dizziness. RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE: Orally disintegrating rimegepant provides a novel mechanism of action for the treatment of acute migraine. When patients experience inadequate relief from other therapies, have contraindications to triptans, or are unable to tolerate the adverse effects of triptans, rimegepant is a promising therapeutic option. CONCLUSION: Rimegepant ODT is an efficacious migraine treatment option with a novel mechanism of action, convenient dosage form, and limited adverse effect profile.

No "Wearing-Off Effect" Seen in Quarterly or Monthly Dosing of Fremanezumab: Subanalysis of a Randomized Long-Term Study.

OBJECTIVE: To evaluate whether quarterly or monthly administration of fremanezumab for migraine prevention exhibits a pattern of decreased efficacy toward the end of the dosing interval (wearing-off effect). BACKGROUND: The main goals of migraine preventive treatment are to reduce the frequency, severity, and duration of migraine attacks, and migraine-associated disability. Wearing-off refers to the phenomenon whereby clinical symptoms return or worsen before the next dose of a drug is due and has been reported previously with migraine preventive medications. DESIGN AND METHODS: This was a long-term, 12-month, multicenter, randomized, double-blind, parallel-group phase 3 study (NCT02638103) that included chronic (CM) and episodic migraine (EM) patients who rolled over from the 12-week phase 3 HALO CM (NCT02621931) and EM trials (NCT02629861), as well as an additional subset of 312 new patients. Patients with CM or EM received fremanezumab either monthly or quarterly. In this post hoc analysis, for selected months, the difference in the average number of migraine days between weeks 1-2 and weeks 3-4, between weeks 1-3 and week 4, and between weeks 1-2 and weeks 11-12 were calculated. RESULTS: A total of 1890 patients (CM, 1110; EM, 780) were enrolled. At months 3, 6, 9, and 15, there were no substantial differences in mean weekly migraine days between weeks 1-2 and weeks 3-4 or between weeks 1-3 and week 4 with quarterly or monthly fremanezumab in the CM or EM subgroups. There were no substantial increases in mean weekly migraine days between weeks 1-2 and weeks 11-12 during the first quarter of treatment (months 1-3) or the second quarter of treatment (months 4-6) with quarterly or monthly fremanezumab in the CM or EM subgroups. Across both dosing subgroups in CM and EM patients, the mean weekly number of migraine days decreased substantially (30%-42%) during the first 2 weeks; decreases in weekly migraine days remained steady during the last 2 weeks of the first quarter, with a similar maintenance of response during the second quarter. CONCLUSIONS: This analysis of data from a long-term, phase 3 study showed that patients receiving quarterly fremanezumab or monthly fremanezumab did not experience a wearing-off effect toward the end of the dosing interval.

Selective Targeting of αvß5 Integrin in HepG2 Cell Line by RGDechi15D Peptide.

Recently, the research community has become increasingly concerned with the receptor αvß5, a member of the well-known integrin family. Different ongoing studies have evidenced that αvß5 integrin regulates not only physiological processes but also a wide array of pathological events, suggesting the receptor as a valuable biomarker to specifically target for therapeutic/diagnostic purposes. Remarkably, in some tumors the involvement of the receptor in cell proliferation, tumor dissemination and angiogenesis is well-documented. In this scenario, the availability of a selective αvß5 antagonist without 'off-target' protein effects may improve survival rate in patients with highly aggressive tumors, such as hepatocellular carcinoma. We recently reported a cyclic peptide, RGDechi15D, obtained by structure-activity studies. To our knowledge it represents the first peptide-based molecule reported in the literature able to specifically bind αvß5 integrin and not cross react with αvß3. Here we demonstrated the ability of the peptide to diminish both adhesion and invasion of HepG2 cells, an in vitro model system for hepatocellular carcinoma, to reduce the cell proliferation through an apoptotic process, and to interfere with the PI3K pathway. The peptide, also decreases the formation of new vessels in endothelial cells. Taken together these results indicate that the peptide can be considered a promising molecule with properties suited to be assessed in the future for its validation as a selective therapeutic/diagnostic weapon in hepatocarcinoma.

Safety and Pharmacokinetics of CXCR4 Peptide Antagonist, LY2510924, in Combination with Durvalumab in Advanced Refractory Solid Tumors.

Purpose: This was an open-label phase 1a study assessing the maximum tolerated dose (MTD), safety, and tolerability of CXCR4 peptide antagonist, LY2510924, administered in combination with durvalumab in patients with advanced refractory solid tumors. Methods: Patients received LY2510924 at 20, 30, or 40 mg subcutaneous (SC) once daily in combination with durvalumab at 1500 mg intravenously (IV) on day 1 of each 28-day cycle. The primary objective was to assess the MTD and safety of LY2510924 SC daily in combination with durvalumab in patients with advanced (metastatic and/or unresectable) solid tumors. Secondary objectives included pharmacokinetics (PK) and the antitumor activity of LY2510924 in combination with durvalumab. Exploratory objectives were biomarker analysis, including pharmacodynamic markers, relevant to LY2510924 and durvalumab, including immune functioning, drug targets, cancer-related pathways, and the disease state. Results: Nine patients (three each at 20, 30, and 40 mg) were enrolled in the study (eight patients with pancreatic cancer and one patient with rectal cancer). The majority of patients completed one or two cycles (100.0% ≥ 1 cycle; 88.9% ≥ 2 cycles) of LY2510924 and durvalumab. No dose limiting toxicities were reported. Most common (>10%) treatment-emergent adverse events were injection-site reaction (44.4%), fatigue (33.3%), and increased white blood cell count (33.3%). PK parameters for combination were similar to those reported in previous studies when given as monotherapy. Best overall response of stable disease was observed in four (44.4%) patients and one patient had unconfirmed partial response. Conclusion: The recommended phase 2 dose is 40 mg SC once-daily LY2510924 in combination with durvalumab 1500 mg IV and showed acceptable safety and tolerability in patients with advanced refractory tumors.

SPA: a peptide antagonist that acts as a cell-penetrating peptide for drug delivery.

Although cell-penetrating peptides (CPPs) has been proven to be efficient transporter for drug delivery, ideal peptide vectors for tumor therapy are still being urgently sought. Peptide antagonists have attracted substantial attention as targeting molecules because of their high tumor accumulation and antitumor activity compared with agonists. SPA, a derivative of substance P, is a potent antagonist that exhibits antitumor activity. Based on the amino acid composition of SPA, we speculate that it can translocate across cell membranes as CPPs do. In this study, our results demonstrated that SPA could enter cells similarly to a CPP. As a vector, SPA could efficiently deliver camptothecin and plasmids into cells. In addition, our results showed that SPA exhibited low toxicity to normal cells and high enzymatic stability. Taken together, our results validated the ability of SPA for efficient drug delivery. More importantly, our study opens a new avenue for designing ideal CPPs based on peptide antagonists.

VIP is involved in peripheral CRF-induced stimulation of propulsive colonic motor function and diarrhea in male rats.

We investigated whether vasoactive intestinal peptide (VIP) and/or prostaglandins contribute to peripheral corticotropin-releasing factor (CRF)-induced CRF1 receptor-mediated stimulation of colonic motor function and diarrhea in rats. The VIP antagonist, [4Cl-D-Phe6, Leu17]VIP injected intraperitoneally completely prevented CRF (10 µg/kg ip)-induced fecal output and diarrhea occurring within the first hour after injection, whereas pretreatment with the prostaglandins synthesis inhibitor, indomethacin, had no effect. In submucosal plexus neurons, CRF induced significant c-Fos expression most prominently in the terminal ileum compared with duodenum and jejunum, whereas no c-Fos was observed in the proximal colon. c-Fos expression in ileal submucosa was colocalized in 93.4% of VIP-positive neurons and 31.1% of non-VIP-labeled neurons. CRF1 receptor immunoreactivity was found on the VIP neurons. In myenteric neurons, CRF induced only a few c-Fos-positive neurons in the ileum and a robust expression in the proximal colon (17.5 ± 2.4 vs. 0.4 ± 0.3 cells/ganglion in vehicle). The VIP antagonist prevented intraperitoneal CRF-induced c-Fos induction in the ileal submucosal plexus and proximal colon myenteric plexus. At 60 min after injection, CRF decreased VIP levels in the terminal ileum compared with saline (0.8 ± 0.3 vs. 2.5 ± 0.7 ng/g), whereas VIP mRNA level detected by qPCR was not changed. These data indicate that intraperitoneal CRF activates intestinal submucosal VIP neurons most prominently in the ileum and myenteric neurons in the colon. It also implicates VIP signaling as part of underlying mechanisms driving the acute colonic secretomotor response to a peripheral injection of CRF, whereas prostaglandins do not play a role. NEW & NOTEWORTHY Corticotropin-releasing factor (CRF) in the gut plays a physiological role in the stimulation of lower gut secretomotor function induced by stress. We showed that vasoactive intestinal peptide (VIP)-immunoreactive neurons in the ileal submucosal plexus expressed CRF1 receptor and were prominently activated by CRF, unlike colonic submucosal neurons. VIP antagonist abrogated CRF-induced ileal submucosal and colonic myenteric activation along with functional responses (defecation and diarrhea). These data point to VIP signaling in ileum and colon as downstream effectors of CRF.

Distinct mobilization of leukocytes and hematopoietic stem cells by CXCR4 peptide antagonist LY2510924 and monoclonal antibody LY2624587.

Stromal cell-derived factor-1 (SDF-1) and its receptor CXCR4 play a critical role in mobilization and redistribution of immune cells and hematopoietic stem cells (HSCs). We evaluated effects of two CXCR4-targeting agents, peptide antagonist LY2510924 and monoclonal antibody LY2624587, on mobilizing HSCs and white blood cells (WBCs) in humans, monkeys, and mice. Biochemical analysis showed LY2510924 peptide blocked SDF-1/CXCR4 binding in all three species; LY2624587 antibody blocked binding in human and monkey, with minimal activity in mouse. Cellular analysis showed LY2624587 antibody, but not LY2510924 peptide, down-regulated cell surface CXCR4 and induced hematological tumor cell death; both agents have been shown to inhibit SDF-1/CXCR4 interaction and downstream signaling. In animal models, LY2510924 peptide induced robust, prolonged, dose- and time-dependent WBC and HSC increases in mice and monkeys, whereas LY2624587 antibody induced only moderate, transient increases in monkeys. In clinical trials, similar pharmacodynamic effects were observed in patients with advanced cancer: LY2510924 peptide induced sustained WBC and HSC increases, while LY2624587 antibody induced only minimal, transient WBC changes. These distinct pharmacodynamic effects in two different classes of CXCR4 inhibitors are clinically important and should be carefully considered when designing combination studies with immune checkpoint inhibitors or other agents for cancer therapy.