Research Project
9059113
DESCRIPTION (provided by applicant): Development of Anti-OLAM Aptamers as Novel Analgesics (Phase 2) The management of pain remains a major health care problem due to an incomplete understanding of pain mechanisms. TRPV1, a prominent member of the transient receptor potential (TRP) family of ligand-gated ion channels, detects noxious chemical and physical stimuli in peripheral tissues. Both pharmacological and gene deletion studies have demonstrated a pivotal role for TRPV1 in inflammatory heat hyperalgesia and other pain conditions. Oxidized linoleic acid metabolites (OLAMs) have been recently demonstrated to comprise a novel family of endogenous TRPV1 agonists that contribute to acute and inflammatory pain conditions. Therefore, compounds that block the OLAM system are likely to constitute a novel family of analgesics. In direct support of this prediction, Phase 1 data provided herein demonstrate that injection of high affinity DNA aptamers developed against two of the major OLAMs: 9-HODE and 13-HODE, produced significant analgesia in patch- clamp and rat behavioral models of heat pain. Although these data provide evidence for proof-of-concept, the aptamers must be developed into heavier conjugates in order to avoid rapid clearance by the kidneys and other major organs. Accordingly, Operational Technologies Corporation (OpTech) proposes to continue developing its successful high affinity anti-OLAM aptamers from Phase 1 into long-lived aptamer conjugates in vivo which specifically bind to 9-HODE and 13-HODE and neutralize their pain-producing activities for extended periods of time. This would permit replacing anti-HODE polyclonal antibodies with more specific, less expensive and higher affinity DNA aptamers. In Phase 2, OpTech expects to complete several specific aims targeted toward enhancing pharmacokinetics (PK) by addition of ibuprofen to the 3' end (ref. 80), thereby enabling association with serum albumin to add weight and retard renal and hepatic clearance. Alternative, but proven, methods to slow in vivo clearance and protect aptamers in vivo including 3'-polyethylene glycol (PEG) and covalent 3' rat albumin attachment will also be investigated. Moreover, 3-dimensional molecular models of aptamer-HODE interactions will be generated by the Southwest Research Institute (SwRI) to enable potential molecular engineering of improvements to aptamer affinity (already exhibiting low nM KD values) and specificity, if possible, using modified or unnatural deoxynucleotides. In addition to in vitro patch clamp studies in the presence and absence of various doses of the aptamer conjugates, rats will be studied for behavioral changes before and after injection and exposure to 43oC noxious heat with the various aptamer-3'-conjugates. If relatively long- term (on the order of hours) PK is observed and heat/burn analgesia can again be demonstrated, OpTech will seek to file an IND or pre-IND application with the FDA.
