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Nonclinical safety evaluation of erenumab, a CGRP receptor inhibitor for the prevention of migraine.
Calcitonin gene-related peptide (CGRP) and its receptor have been implicated as a key mediator in the pathophysiology of migraine. Thus, erenumab, a monoclonal antibody antagonist of the CGRP receptor, administered as a once monthly dose of 70 or 140 mg has been approved for the preventive treatment of migraine in adults. Due to the species specificity of erenumab, the cynomolgus monkey was used in the pharmacology, pharmacokinetics, and toxicology studies to support the clinical program. There were no effects of erenumab on platelets in vitro (by binding, activation or phagocytosis assays). Specific staining of human tissues with erenumab did not indicated any off-target binding. There were no erenumab-related findings in a cardiovascular safety pharmacology study in cynomolgus monkeys or in vitro in human isolated coronary arteries. Repeat-dose toxicology studies conducted in cynomolgus monkeys at dose levels up to 225 mg/kg (1 month) or up to 150 mg/kg (up to 6 months) with twice weekly subcutaneous (SC) doses showed no evidence of erenumab-mediated adverse toxicity. There were no effects on pregnancy, embryo-fetal or postnatal growth and development in an enhanced pre-postnatal development study in the cynomolgus monkey. There was evidence of placental transfer of erenumab based on measurable serum concentrations in the infants up to 3 months post birth. The maternal and developmental no-observed-effect level (NOEL) was the highest dose tested (50 mg/kg SC Q2W). These nonclinical data in total indicate no safety signal of concern to date and provide adequate margins of exposure between the observed safe doses in animals and clinical dose levels.
Learn More >The majority of self-management interventions are designed with a narrow focus on patient skills and fail to consider their potential as "catalysts" for improving care delivery. A project was undertaken to develop a patient self-management resource to support evidence-based, person-centered care for cancer pain and overcome barriers at the levels of the patient, provider, and health system.
Learn More >Psychological and personality factors, socioeconomic status, and brain properties all contribute to chronic pain but have essentially been studied independently. Here, we administered a broad battery of questionnaires to patients with chronic back pain (CBP) and collected repeated sessions of resting-state functional magnetic resonance imaging (fMRI) brain scans. Clustering and network analyses applied on the questionnaire data revealed four orthogonal dimensions accounting for 56% of the variance and defining chronic pain traits. Two of these traits-Pain-trait and Emote-trait-were associated with back pain characteristics and could be related to distinct distributed functional networks in a cross-validation procedure, identifying neurotraits. These neurotraits showed good reliability across four fMRI sessions acquired over five weeks. Further, traits and neurotraits all related to the income, emphasizing the importance of socioeconomic status within the personality space of chronic pain. Our approach is a first step in providing metrics aimed at unifying the psychology and the neurophysiology of chronic pain applicable across diverse clinical conditions.
Learn More >Residual lower-limb pain after low back surgery (postsurgical sciatica) and complex regional pain syndrome (CRPS) involving a lower limb are separate conditions but may share some mechanisms (eg, tissue inflammation, neuroimmune disturbances, and central neuroplasticity). As adrenergically evoked pain contributes, in part, to CRPS, whether an adrenergic mechanism also contributes to postsurgical sciatica was investigated in this study. Immunohistochemistry was used to identify α1-adrenoceptors (α1-AR) on nerve fibres and other targets in the affected and contralateral skin of 25 patients with postsurgical sciatica, and α1-AR expression was investigated in relation to pain and pinprick hyperalgesia after intradermal injection of the α1-AR agonist phenylephrine. In addition, quantitative sensory testing was performed on all 4 limbs and on each side of the forehead. α1-AR expression was greater in keratinocytes (but not blood vessels or nerve fibres) in the symptomatic than contralateral leg, and dermal nerve fibre density was reduced in both legs. However, distal adrenergic involvement in pain in postsurgical sciatica seems unlikely, as neither heightened α1-AR expression in keratinocytes nor reduced dermal nerve fibre density were associated with pain or hyperalgesia to intradermal phenylephrine injection. Sensitivity to pressure-pain, pinprick, and cold-pain was greater in the ipsilateral than contralateral forehead of the entire cohort, but sensory disturbances were most pronounced in patients with additional CRPS-like features. Together, these findings suggest that bilateral distal neuropathy and central neuroplastic changes are involved not only in the pathophysiology of CRPS but also in postsurgical sciatica. This may have treatment implications for patients with postsurgical sciatica.
Learn More >The spinal administration of opioids can cause intense pruritisInteractions between specific μ-opioid receptor isoforms and the gastrin releasing peptide receptor in spinal tissues likely mediate morphine-induced pruritus WHAT THIS ARTICLE TELLS US THAT IS NEW: Human spinal cord tissue expresses the 1Y isoform of the μ-opioid receptor, and that isoform functionally interacts with the gastrin releasing peptide receptor to cause cellular calcium influxBlocking interactions between the 1Y isoform and the gastrin releasing peptide receptor does not reduce opioid analgesiaEliminating interactions between the 1Y isoform and the gastrin releasing peptide receptor or reducing 1Y isoform activation may reduce opioid-induced pruritis BACKGROUND:: Although spinal opioids are safe and effective, pruritus is common and distressing. The authors previously demonstrated in mouse spinal cord that interactions between μ-opioid receptor isoform 1D and gastrin releasing peptide receptor mediate morphine-induced scratch. The C-terminal of 1D inhibits morphine-induced scratch without affecting analgesia. The authors hypothesize that human spinal cord also contains itch-specific μ-opioid receptor isoforms which interact with gastrin releasing peptide receptor.
Learn More >In the course of investigating how common clinical treatments and adaptive technologies affect recovery after spinal cord injury (SCI), we discovered that a clinically-modeled hindlimb stretching protocol dramatically, but transiently, reduces locomotor function. Nociceptive sensory input is capable of altering motor output at the spinal level, and nociceptive neurons are sensitized after SCI. Here we tested the possibility that the stretch-induced motor deficits required the presence of nociceptors using neonatal capsaicin induced depletion of TRPV1+ nociceptive neurons. Following maturation, animals received 25 g-cm contusive SCI at T10. After plateau of locomotor recovery at 6 weeks, daily stretching was performed for 3 weeks, followed by 2 weeks without stretch, and again for two additional weeks. Animals were sacrificed 2 h after the last stretching session for histological assessments. The expected stretch-induced drops in locomotor function were observed in nociceptor-intact animals but were nearly absent in nociceptor-depleted animals. These functional changes were accompanied by corresponding increases in the number of c-Fos + nuclei throughout the lumbar enlargement. As expected, nociceptor-depleted animals had very little CGRP+ axonal innervation of the dorsal horn. However, in nociceptor-intact animals the expected post-SCI increase in CGRP+ innervation was significantly enhanced in animals that received stretching, implying additional stretch-induced intraspinal sprouting. These results indicate that locomotor dysfunction following hindlimb muscle stretch in animals with incomplete SCI involves C-fibers, adding a negative post-SCI role to their adaptive roles (e.g., bladder control), and suggesting that the clinical use of muscle stretching to combat contractures and spasticity may be unintentionally detrimental to locomotor function.
Learn More >Endometriosis, a systemic disease that is often painful and chronic, affects ∼10% of reproductive-age women. The disease can negatively impact a patient's physical and emotional well-being, quality of life, and productivity. Endometriosis also places significant economic and social burden on patients, their families, and society as a whole. Despite its high prevalence and cost, endometriosis remains underfunded and under-researched – greatly limiting our understanding of the disease and slowing much-needed innovation in diagnostic and treatment options. Due in part to the societal normalization of women's pain and stigma around menstrual issues, there is also a lack of disease awareness among patients, health care providers, and the public. The Society for Women's Health Research convened an interdisciplinary group of expert researchers, clinicians, and patients for a roundtable meeting to review the current state of the science on endometriosis and identify areas of need to improve a woman's diagnosis, treatment, and access to quality care. Comprehensive and interdisciplinary approaches to disease management and increased education and disease awareness for patients, health care providers, and the public are needed to remove stigma, increase timely and accurate diagnosis and treatment, and allow for new advancements.
Learn More >Small nerve fibers that bind the isolectin B4 (IB4 C-fibers) are a subpopulation of primary afferent neurons that are involved in nociceptive sensory transduction and do not express the neuropeptides substance P and calcitonin-gene related peptide (CGRP). Several studies have attempted to elucidate the functional role of IB4-nociceptors in different models of pain. However, a functional characterization of the non-peptidergic nociceptors in mediating mechanical inflammatory hypersensitivity in mice is still lacking. To this end, in the present study, the neurotoxin IB4-Saporin (IB4-Sap) was employed to ablate non-peptidergic C-fibers. Firstly, we showed that intrathecal (i.t.) administration of IB4-Sap in mice depleted non-peptidergic C-fibers, since it decreased the expression of purinoceptor 3 (P2X) and transient receptor potential cation channel subfamily V member 1 (TRPV1) in the dorsal root ganglia (DRGs) as well as IB4 labelling in the spinal cord. Non-peptidergic C-fibers depletion did not alter the mechanical nociceptive threshold, but it inhibited the mechanical inflammatory hypersensitivity induced by glial cell-derived neurotrophic factor (GDNF), but not nerve growth factor (NGF). Depletion of non-peptidergic C-fibers abrogated mechanical inflammatory hypersensitivity induced by carrageenan. Finally, it was found that the inflammatory mediators PGE and epinephrine produced a mechanical inflammatory hypersensitivity that was also blocked by depletion of non-peptidergic C-fibers. These data suggest that IB4-positive nociceptive nerve fibers are not involved in normal mechanical nociception but are sensitised by inflammatory stimuli and play a crucial role in mediating mechanical inflammatory hypersensitivity.
Learn More >The associations between family strain, depression, and chronic pain interference vary across individuals, suggesting moderated relations, and one possible moderator is somatic amplification. The current study examined a moderated mediation model that investigated (a) whether depression mediated the relation between non-spouse family strain and chronic pain interference and (b) whether somatic amplification moderated the association between depression and chronic pain interference.
Learn More >Transient receptor potential ankyrin 1 (TRPA1) channels may have a role in migraine as some substances known to cause headache activate the channel. In the craniovascular system such activation causes a calcitonin gene-related peptide (CGRP)-dependent increase in meningeal blood flow. TRPA1 channels in the endothelium of cerebral arteries cause vasodilation when activated. The headache preventive substance feverfew inhibits activation of TRPA1 channels. In this study we aim to compare and characterize the effect of the TRPA1 agonist allyl isothiocyanate (AITC) on the diameter of rat dural and pial arteries in vivo.
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