Tara A. Macey

Correlates of prescription opioid initiation and long-term opioid use in veterans with persistent pain.

Objectives:Little is known about how opioid prescriptions for chronic pain are initiated. We sought to describe patterns of prescription opioid initiation, identify correlates of opioid initiation, and examine correlates of receipt of chronic opioid therapy (COT) among veterans with persistent noncancer pain. Methods:Using Veterans Affairs administrative data, we identified 5961 veterans from the Pacific Northwest with persistent elevated pain intensity scores who had not been prescribed opioids in the prior 12 months. We compared veterans not prescribed opioids over the subsequent 12 months with those prescribed any opioid and to those prescribed COT (>90 consecutive days). Results:During the study year, 35% of the sample received an opioid prescription and 5% received COT. Most first opioid prescriptions were written by primary care clinicians. Veterans prescribed COT were younger, had greater pain intensity, and high rates of psychiatric and substance use disorders compared with veterans in the other 2 groups. Among patients receiving COT, 29% were prescribed long-acting opioids, 37% received 1 or more urine drug screens, and 24% were prescribed benzodiazepines. Adjusting for age, sex, and baseline pain intensity, major depression [odds ratio 1.24 (1.10-1.39); 1.48 (1.14-1.93)], and nicotine dependence [1.34 (1.17-1.53); 2.02 (1.53-2.67)] were associated with receiving any opioid prescription and with COT, respectively. Discussion:Opioid initiations are common among veterans with persistent pain, but most veterans are not prescribed opioids long-term. Psychiatric disorders and substance use disorders are associated with receiving COT. Many Veterans receiving COT are concurrently prescribed benzodiazepines and many do not receive urine drug screening; additional study regarding practices that optimize safety of COT in this population is indicated.

Dopamine D2 receptor stimulation of mitogen‐activated protein kinases mediated by cell type‐dependent transactivation of receptor tyrosine kinases

Dopamine D2 receptor activation of extracellular signal‐regulated kinases (ERKs) in non‐neuronal human embryonic kidney 293 cells was dependent on transactivation of the platelet‐derived growth factor (PDGF) receptor, as demonstrated by the effect of the PDGF receptor inhibitors tyrphostin A9 and AG 370 on quinpirole‐induced phosphorylation of ERKs and by quinpirole‐induced tyrosine phosphorylation of the PDGF receptor. In contrast, ectopically expressed D2 receptor or endogenous D2‐like receptor activation of ERKs in NS20Y neuroblastoma cells, which express little or no PDGF receptor, or in rat neostriatal neurons was largely dependent on transactivation of the epidermal growth factor (EGF) receptor, as demonstrated using the EGF receptor inhibitor AG 1478 and by quinpirole‐induced phosphorylation of the EGF receptor. The D2 receptor agonist quinpirole enhanced the coprecipitation of D2 and EGF receptors in NS20Y cells, suggesting that D2 receptor activation induced the formation of a macromolecular signaling complex that includes both receptors. Transactivation of the EGF receptor also involved the activity of a matrix metalloproteinase. Thus, although D2 receptor stimulation of ERKs in both cell lines was decreased by inhibitors of ERK kinase, Src‐family protein tyrosine kinases, and serine/threonine protein kinases, D2‐like receptors activated ERKs via transactivation of the EGF receptor in NS20Y neuroblastoma cells and rat embryonic neostriatal neurons, but via transactivation of the PDGF receptor in 293 cells.

Exome Sequencing of Cell-Free DNA from Metastatic Cancer Patients Identifies Clinically Actionable Mutations Distinct from Primary Disease

The identification of the molecular drivers of cancer by sequencing is the backbone of precision medicine and the basis of personalized therapy; however, biopsies of primary tumors provide only a snapshot of the evolution of the disease and may miss potential therapeutic targets, especially in the metastatic setting. A liquid biopsy, in the form of cell-free DNA (cfDNA) sequencing, has the potential to capture the inter- and intra-tumoral heterogeneity present in metastatic disease, and, through serial blood draws, track the evolution of the tumor genome. In order to determine the clinical utility of cfDNA sequencing we performed whole-exome sequencing on cfDNA and tumor DNA from two patients with metastatic disease; only minor modifications to our sequencing and analysis pipelines were required for sequencing and mutation calling of cfDNA. The first patient had metastatic sarcoma and 47 of 48 mutations present in the primary tumor were also found in the cell-free DNA. The second patient had metastatic breast cancer and sequencing identified an ESR1 mutation in the cfDNA and metastatic site, but not in the primary tumor. This likely explains tumor progression on Anastrozole. Significant heterogeneity between the primary and metastatic tumors, with cfDNA reflecting the metastases, suggested separation from the primary lesion early in tumor evolution. This is best illustrated by an activating PIK3CA mutation (H1047R) which was clonal in the primary tumor, but completely absent from either the metastasis or cfDNA. Here we show that cfDNA sequencing supplies clinically actionable information with minimal risks compared to metastatic biopsies. This study demonstrates the utility of whole-exome sequencing of cell-free DNA from patients with metastatic disease. cfDNA sequencing identified an ESR1 mutation, potentially explaining a patients resistance to aromatase inhibition, and gave insight into how metastatic lesions differ from the primary tumor.

Patterns and correlates of prescription opioid use in OEF/OIF veterans with chronic noncancer pain.

OBJECTIVES Little is known about the treatment Operation Enduring Freedom/Operation Iraqi Freedom (OEF/OIF) veterans receive for chronic noncancer pain (CNCP). We sought to describe the prevalence of prescription opioid use, types, and doses of opioids received and to identify correlates of receiving prescription opioids for CNCP among OEF/OIF veterans. DESIGN Retrospective review of Veterans Affairs (VA) administrative data. SETTING Ambulatory clinics within a VA regional health care network. PATIENTS OEF/OIF veterans who had at least three elevated pain screening scores within a 12-month period in 2008. Within this group, those prescribed opioids (N = 485) over the next 12 months were compared with those not prescribed opioids (N = 277). In addition, patients receiving opioids short term (<90 days, N = 284) were compared with patients receiving them long term (≥90 consecutive days, N = 201). RESULTS Of 762 OEF/OIF veterans with CNCP, 64% were prescribed at least one opioid medication over the 12 months following their index dates. Of those prescribed an opioid, 59% were prescribed opioids short term and 41% were prescribed opioids long term. The average morphine-equivalent opioid dose for short-term users was 23.7 mg (standard deviation [SD] = 20.5) compared with 40.8 mg (SD = 36.1) for long-term users (P < 0.001). Fifty-one percent of long-term opioid users were prescribed short-acting opioids only, and one-third were also prescribed sedative hypnotics. In adjusted analyses, diagnoses of low back pain, migraine headache, posttraumatic stress disorder, and nicotine use disorder were associated with an increased likelihood of receiving an opioid prescription. CONCLUSION Prescription opioid use is common among OEF/OIF veterans with CNCP and is associated with several pain diagnoses and medical conditions.

Androgen and PARP-1 regulation of TRPM2 channels after ischemic injury

The calcium-permeable transient receptor potential M2 (TRPM2) ion channel was recently demonstrated to have a sexually dimorphic contribution to ischemic brain injury, with inhibition or knockdown of the channel protecting male brain preferentially. We tested the hypothesis that androgen signaling is required for this male-specific cell-death pathway. Additionally, we tested the hypothesis that differential activation of the enzyme poly (ADP-ribose) polymerase-1 (PARP-1) is responsible for male-specific TRPM2 channel activation and neuronal injury. We observed that administration of the TRPM2 inhibitor clotrimazole (CTZ) 2 hours after onset of ischemia reduced infarct volume in male mice and that protection from ischemic damage by CTZ was abolished by removal of testicular androgens (castration; CAST) and rescued by androgen replacement. Male PARP-1 knockout mice had reduced ischemic damage compared with WT mice and inhibition of TRPM2 with CTZ failed to reduce infarct size. Lastly, we observed that ischemia increased PARP activity in the peri-infarct region of male mice to a greater extent than female mice and the difference was abolished in CAST male mice. Data presented in the current study indicate that TRPM2-mediated neuronal death in the male brain requires intact androgen signaling and PARP-1 activity.

Dopamine D1 receptor interaction with arrestin3 in neostriatal neurons

Dopamine D1 receptor interactions with arrestins have been characterized using heterologously expressed D1 receptor and arrestins. The purpose of this study was to investigate the interaction of the endogenous D1 receptor with endogenous arrestin2 and 3 in neostriatal neurons. Endogenous arrestin2 and 3 in striatal homogenates bound to the C‐terminus of the D1 receptor in a glutathione‐S‐transferase (GST) pulldown assay, with arrestin3 binding more strongly. The D1 C‐terminus and, to a lesser extent, the third cytoplasmic loop also bound purified arrestin2 and 3. In neostriatal neurons, 2, 5, and 20 min agonist treatment increased the colocalization of the D1 receptor and arrestin3 immunoreactivity without altering the colocalization of the D1 receptor and arrestin2. Further, agonist treatment for 5 and 20 min caused translocation of arrestin3, but not arrestin2, to the membrane. The binding of arrestin3, but not arrestin2, to the D1 receptor was increased as assessed by coimmunoprecipitation after agonist treatment for 5 and 20 min. Agonist treatment of neurons induced D1 receptor internalization (35–45%) that was maximal within 2–5 min, a time‐course similar to that of the increase in colocalization of the D1 receptor with arrestin3. These data indicate that the D1 receptor preferentially interacts with arrestin3 in neostriatal neurons.

Evidence That Calmodulin Binding to the Dopamine D2 Receptor Enhances Receptor Signaling

The Ca2+ sensor calmodulin (CaM) regulates numerous proteins involved in G protein-coupled receptor (GPCR) signaling. CaM binds directly to some GPCRs, including the dopamine D2 receptor. We confirmed that the third intracellular loop of the D2 receptor is a direct contact point for CaM binding using coimmunoprecipitation and a polyHis pull-down assay, and we determined that the D2-like receptor agonist 7-OH-DPAT increased the colocalization of the D2 receptor and endogenous CaM in both 293 cells and in primary neostriatal cultures. The N-terminal three or four residues of D2-IC3 were required for the binding of CaM; mutation of three of these residues in the full-length receptor (I210C/K211C/I212C) decreased the coprecipitation of the D2 receptor and CaM and also significantly decreased D2 receptor signaling, without altering the coupling of the receptor to G proteins. Taken together, these findings suggest that binding of CaM to the dopamine D2 receptor enhances D2 receptor signaling.

Sex Differences in the Medical Care of VA Patients with Chronic Non-Cancer Pain

OBJECTIVE Despite a growing number of women seeking medical care in the veterans affairs (VA) system, little is known about the characteristics of their chronic pain or the pain care they receive. This study sought to determine if sex differences are present in the medical care veterans received for chronic pain. DESIGN Retrospective cohort study using VA administrative data. SUBJECTS The subjects were 17,583 veteran patients with moderate to severe chronic non-cancer pain treated in the Pacific Northwest during 2008. METHODS Multivariate logistic regression assessed for sex differences in primary care utilization, prescription of chronic opioid therapy, visits to emergency departments for a pain-related diagnosis, and physical therapy referral. RESULTS Compared with male veterans, female veterans were more often diagnosed with two or more pain conditions, and had more of the following pain-related diagnoses: fibromyalgia, low back pain, inflammatory bowel disease, migraine headache, neck or joint pain, and arthritis. After adjustment for demographic characteristics, pain diagnoses, mental health diagnoses, substance use disorders, and medical comorbidity, women had lower odds of being prescribed chronic opioid therapy (adjusted OR [AOR] 0.67, 95% CI 0.58-0.78), greater odds of visiting an emergency department for a pain-related complaint (AOR 1.40, 95% CI 1.18-1.65), and greater odds of receiving physical therapy (AOR 1.19, 95% CI 1.05-1.33). Primary care utilization was not significantly different between sexes. CONCLUSIONS Sex differences are present in the care female veterans receive for chronic pain. Further research is necessary to understand the etiology of the observed differences and their associations with clinical outcomes.

Patterns of care and side effects for patients prescribed methadone for treatment of chronic pain.

OBJECTIVES This manuscript evaluates physician monitoring practices and incidence of cardiac side effects following initiation of methadone for treatment of chronic pain as compared to patients who began treatment for chronic pain with morphine sustained release (SR). DESIGN We retrospectively reviewed medical record data on all new initiations of methadone and compared results of physician monitoring practices to patients with new initiations of morphine SR. A standardized chart tool was used to capture clinical data. Data related to health service utilization and clinical diagnoses were obtained from the VA clinical information system. SETTING A single VA Medical Center in the Pacific Northwest. PATIENTS Chronic pain patients prescribed methadone (n=92) or morphine (n=90) in the calendar year 2008. RESULTS There was no difference between patients prescribed methadone versus patients prescribed morphine SR in the likelihood of receiving an electrocardiogram (ECG) prior to initiating medication (53 percent versus 54 percent) or in the year after opioid initiation (37 percent versus 40 percent). The two groups also did not differ in rates of developing prolonged rate-corrected (QTc) intervals (>450 ms) (11 percent versus 17 percent). Seventy-two percent of all patients discontinued their long-acting opioid regimens before 90 days due to adverse effects or insufficient pain relief. CONCLUSION Despite recommendations for standardized assessment and cardiac risk monitoring, few patients prescribed methadone received an ECG, and this occurred at a rate that did not differ from patients prescribed morphine SR. Patients discontinued both medications at high rates. Further research is needed to evaluate the clinical significance of QTc prolongation in patients treated with methadone.

Functional genomic landscape of acute myeloid leukaemia.

The implementation of targeted therapies for acute myeloid leukaemia (AML) has been challenging because of the complex mutational patterns within and across patients as well as a dearth of pharmacologic agents for most mutational events. Here we report initial findings from the Beat AML programme on a cohort of 672 tumour specimens collected from 562 patients. We assessed these specimens using whole-exome sequencing, RNA sequencing and analyses of ex vivo drug sensitivity. Our data reveal mutational events that have not previously been detected in AML. We show that the response to drugs is associated with mutational status, including instances of drug sensitivity that are specific to combinatorial mutational events. Integration with RNA sequencing also revealed gene expression signatures, which predict a role for specific gene networks in the drug response. Collectively, we have generated a dataset—accessible through the Beat AML data viewer (Vizome)—that can be leveraged to address clinical, genomic, transcriptomic and functional analyses of the biology of AML.Analyses of samples from patients with acute myeloid leukaemia reveal that drug response is associated with mutational status and gene expression; the generated dataset provides a basis for future clinical and functional studies of this disease.