Raymond A. Dionne - US grants

Patients with Complex Regional Pain Syndrome, type I (CRPS-I), formerly termed Reflex Sympathetic Dystrophy, have chronic, post-traumatic pain that spreads beyond the distribution of any single peripheral nerve without evidence of major peripheral nerve damage. A similar disorder, Causalgia, re-named CRPS-II, presents with clear evidence of nerve injury. No successful drug treatment exists for these disorders. Neurotropin is a non-protein extract of cutaneous tissue from rabbits inoculated with vaccinia virus. Neurotropin tablets, prepared from the tissue extract, have been used extensively in Japan to treat CRPS and other painful conditions; however, the drug has not undergone clinical therapeutic testing in the United States. Protocol (00-NR-0200) was designed to carry out double-blind, placebo-controlled, crossover studies about clinical efficacy of Neurotropin (FDA IND # 60,994) for chronic neuropathic pain in outpatients with CRPS-I or II. [unreadable] [unreadable] Subjects of this double blind cross-over study receive Neurotropin or placebo tablets for 5 weeks, then no trial medication for at least 1 week, and then the other trial drug for the next 5 weeks. That is, patients who took placebo the first 5 weeks will take Neurotropin the second 5 weeks and vice versa. Thirty male and female patients (age range: 18 and older) meeting the diagnostic criteria established by the International Association for the Study of Pain for diagnosis of CRPS who have been treated unsuccessfully with a current standard therapeutic regimen will be selected for the study. The CRPS patients are given the test drug (4 tablets, twice daily) orally for 5 weeks. After the washout period (at least 1 week), the other test drug was administered to the same patient. Before first treatment phase and after 5 weeks of each treatment phase, the pain sensation (area, spontaneous pain intensity, allodynia, hyperalgesia), quality of life (SF-36 questionnaire), autonomic function (skin color, skin blood flow and temperature), edema/swelling of affected limb, and active range of motion of involved joints are measured.[unreadable] [unreadable] Eleven patients have completed the study. Since the beginning in October 2000, we have screed about 350 patients who were referred with a diagnois of CRPS. However, most participants were in chronic stage of CRPS and/or symptoms to both sides of the body, and therefore did not meet the inclusion criteria for the study, three patients have been dropped from the study. There were no adverse effects related to test drugs in any of the patients who have completed the study. All of these patients elected to have the optional additional 5-week treatment with the agent that they thought had a beneficial effect. However, because the code of this study drug has not been broken we do not know how often the placebo or the putative active drug was chosen. [unreadable] [unreadable] In order to expedite the patient enrollment to the study, we allowed inclusion for screening patients formerly excluded because the injury involved a proximal region, such as the unilateral shoulder or inguinal region. However, we will keep unchanged the inclusion criteria for the limb regions demonstrating the typical signs and symptoms of CRPS. We also increased our efforts in reaching physicians and other professionals who treat CRPS patients and made more widely available information regarding this study using sponsored internet links on search engines. Recently, one male patient was enrolled in the study. The continuation of this study was approved by the CNS IRB in September 2008.[unreadable] [unreadable] A parallel protocol is evaluating the use of neurotropin for fibromyalgia (FM), a disabling disorder that primarily affects women and presents a therapeutic challenge. Because of the reported efficacy of Neurotropin for treatment of FM in Japan, we have planned a double-blind, placebo-controlled, crossover studies to confirm these reports. The study is designed to test whether Neurotropin treatment will affect spontaneous pain, sensitivity to pressure-induced pain at specific locations, and/or the ability of the patient to function in normal activities as well as affect the fatigue, sleep disturbance, anxiety and mood disorder frequently seen in fibromyalgia patients.[unreadable] [unreadable] Female patients (age range: 18 and older) meeting the criteria established by the American College of Rheumatology for diagnosis of FM who have been treated unsuccessfully with a current standard therapeutic regimen are selected for the study. The criteria are (A) a history of widespread pain (in all quadrants and back) for more than half of the days in each of the prior three months and (B) the required number (11) of tender points of 18 test sites, which will be determined during the initial physical examination. The average score on the Fibromyalgia Impact Questionnaire (FIQ: a brief 10-item self-administered measure of physical functioning, ability to work and perform activities of daily living, depression, anxiety, sleep, pain, stiffness and fatigue) for patients seen in tertiary care settings is about 50 (with 100 being the maximum, a higher score indicating a greater impairment of health) and we will include only those patients in whom the FIQ score is greater than 30 at the initial evaluation. To be admitted to this study, patients must be willing to continue using only their present medications (including antidepressants) or other forms of care related to the control of FM symptoms during the course of the study.[unreadable] [unreadable] Because Neurotropin may take several weeks to have an effect and because FM has such a spontaneously fluctuating course, in this study test tablets will be administered over a 12-week interval. Neurotropin or matching placebo will be randomly assigned as the first treatment. During the first 12-week treatment patients will be given Neurotropin or placebo tablets. After more than 1 week wash-out period, the patient will receive a second 12-week supply of placebo (for those patients who received Neurotropin tablets) or Neurotropin tablets (for those patients who received placebo tablets). In both treatment phases, the patient is instructed to take 8 tablets daily (4 tablets twice daily), the dosage used in Japan and in another NIH protocol (00-NR-0200) for clinical trial of Neurotropin in patients with CRPS.[unreadable] [unreadable] Before each treatment phase and every 6 week during each treatment phase, the FIQ, SF-36, the manual tender point count, the dolorimetric estimate of overall tenderness and the six minute walk test are measured. Differences in the FIQ scores during and at the end of the study period will be used as the primary outcome measure. The 18 (9 bilateral) specified locations are examined for tender points. The dolorimetric measurement of mean pressure thresholds to elicit pain determined at three paired points (epicondyle, mid-trapezius, and thumbnail) assesses overall tenderness. [unreadable] [unreadable] The continuation of this study (06-NR-0229) was approved by the NIAMS/NIDDK IRB in March 2008. since the initiation of the study, nine patients enrolled in the study, and 4 patients have completed the study, three patients are currently on the first phase medication. Two patients have been dropped from the study. There were no adverse effects related to the test drugs in any of the patients. We anticipate that this study may require 2-3 years to complete.

Pain is multifactorial in origin with both genetic and environmental factors contributing to individual variations. Candidate gene studies on the basis of biological hypotheses have been performed to identify relevant genetic variation in complex traits such as pain. However, the complicated mesh of contributing factors and the thousands of molecules involved in different pain phenotypes makes it difficult to detect responsible genetic variations for an individuals unique susceptibility to pain. It is unlikely that common variations in a single gene act dominantly on pain; rather, the contribution of each gene seems to be subtle, acting on one of multiple pain pathways, making its signal difficult to detect.[unreadable] [unreadable] Even though pain has been one of the most significant and frequent problems affecting quality of life for thousands of years, analgesic therapy is still largely limited to opioids and aspirin-like drugs, with the limitations of these drug classes. The combined impact of the rapid increase in knowledge of diseases and the ability to apply powerful and high capacity technology has raised expectations for more effective and safer medicines for pain management. Developing new treatment strategies for the pain management is also critically dependent on identifying new target molecules and defining pain phenotypes for specific types of pain. Therefore the first step of this project has been to define the characteristics of experimental and clinical pain phenotypes. Contributing factors such as gender, ethnicity and psychological factors predominate over the role of genetic factors in pain and analgesic responses when evaluating groups of patients (Kim et al. 2004a; Kim et al. 2004b). But genetic variability may be important at the level of the individual (Dionne et al. 2005).[unreadable] [unreadable] Based on this project, we found haploblocks from candidate pain genes for each major ethnic population. Human haplotype data of pain related genes provide basic information for the genetic association studies of pain sensitivity and responses to analgesics. We also applied this haplotype data to find the association with experimental pain sensitivity and verified that this method is practically useful in investigating the role of genetics in pain sensitivity (Kim et al. 2006, JMG). We also have performed individual SNP association studies of candidate genes and reported controversial result to the previous studies published in Science, which may be biased with population stratification and small sample size (Kim et al. 2006, Molecular Pain). Efforts of investigating the interactions between psychological factors and pain sensitivity along with their genetic profiles were continued and some of the preliminary reports were presented at the American Pain Society and two of our presentations won Young Investigator Awards (Mittal et al., Lee et al.). Meanwhile we investigated the influence of the genetic variations in prostaglandin synthesis on the clinically induced pain and analgesic responses with oral surgery model. From this, we found that homozygous G/G patients of SNP in the promoter region (-765) of COX-2 gene showed significantly different responses to common analgesic drugs compared to G/C heterozygous and C/C homozygous patients (Lee et al. 2006, CPT). Based on these works, we were invited for review articles from International Association for the Study of Pain (Kim et al. 2005) and Pharmacological Review (in preparation) as well as for symposiums of the annual meeting of American Pain Society in year 2007. We recently initiated whole genome scan study related to clinical pain sensitivity using 500,000 SNPs assay. We have analyzed 60 samples so far and the analysis revealed that 7 SNPs show associations with maximum post-operative pain after local anesthetics offset at the level of p < 10-6. Four of them are uncharacterized, two of them are located in untranslated region (LOC283867 and SIPA1L1)and one is located in an intron (CDKAL1). Further characterization of these 7 regions with dense genotyping may identify genetic loci that contribute to interindividual variability in pain due to tissue injury and the acute inflammation responses following minor surgery.[unreadable] [unreadable] Based on whole genome scale investigation, we plan to narrow the candidate regions from the human genome to scan more densely. Detailed information of the candidate regions with SNPs may provide knowledge for the genetic role in pain and analgesic responses on an individual patient basis. Finally, we can suggest genomic tools such as a human pain gene chip to develop new drugs and test them based on individual genetic information.[unreadable] [unreadable] The role of genetic factors on clinical pain will continue to be studied in acute pain using genotyping, gene and protein expression, and patient reported outcomes to better understand the reciprocal interplay between these factors and the inflammatory cascade. These data will be analyzed with whole genome scan, microarray, ELISA, SNP genotyping and real time PCR. For chronic pain, patients with well characterized neuropathic pain and fibromyalgia will be recruited and similar techniques used to analyze molecular-genetic mechanisms of chronic pain.[unreadable] [unreadable] From these results along with biological knowledge of pain pathways, we will be able to suggest a human pain gene chip to characterize molecular-genetic mechanisms of pain and analgesia at the level of the individual, suggest new targets for analgesic drugs and test the efficacy and adverse reactions of newly developed or currently used drugs.

The dual model of cyclooxygenase (COX) has been the rationale for developing selective COX-2 inhibitors to treat inflammatory pain and avoid the adverse gastrointestinal effects of COX-1 suppression by traditional NSAIDs (tNSAIDs). However, increasing evidence indicates that this model is oversimplified to explain the observed differences in therapeutic and adverse effects among COX-2 inhibitors in clinical and experimental studies. New insights into the biological properties of COX-2 and its response pathway challenge the hypothesis that COX-2 is simply pro-inflammatory and inhibition of COX-2 solely prevents the development of inflammation and ameliorates inflammatory pain. Recent clinical trials reveal that COX-2 inhibition by coxibs is associated with an increased risk of cardiovascular events. While the mechanisms underlying the adverse effects of COX-2 inhibitors have been attributed to an imbalance of prostaglandin I2 and thromboxane A2, it is still unclear whether the adverse effects of coxibs are solely the result of COX-2 inhibition. [unreadable] [unreadable] Using microarray gene expression analysis, we have demonstrated that inhibition of COX-2 by rofecoxib modulates multiple gene expression pathways besides COX-2 cascade in a well-characterized clinical model of acute inflammation (Wang et al., 2006a,b). Inhibition of COX-2, in the presence of acute inflammation, induces changes in gene expression related to the matrix metalloproteinase (MMP) pathway in humans. Our findings indicate a more complex role of COX-2 in the inflammatory cascade and that COX-2-independent pathways are also involved in the rofecoxib-induced anti-inflammatory and analgesic effects at the gene expression level. These changes may impair inflammatory resolution via degradation and remodeling of the extracellular matrix and contribute to the adverse effects attributed to COX-2 inhibition in clinical observations. These results may provide an alternative hypothesis for the therapeutic and the adverse effects attributed to selective inhibition of COX-2. Comprehensive study of the reciprocal interplay between patient reported inflammatory symptoms, signatures of gene/protein expression and the selective anti-inflammatory drugs may lead to development of biomarkers for therapeutic responses and adverse events attributed to coxibs in the treatment of inflammatory disorders.