title: Pharmacological blockade of the vanilloid receptor TRPV1 elicits marked hyperthermia in humans.
abstract: The vanilloid receptor TRPV1 has been identified as a molecular target for the treatment of pain associated with inflammatory diseases and cancer. Hence, TRPV1 antagonists have been considered for therapeutic evaluation in such diseases. During Phase I clinical trials with AMG 517, a highly selective TRPV1 antagonist, we found that TRPV1 blockade elicited marked, but reversible, and generally plasma concentration-dependent hyperthermia. Similar to what was observed in rats, dogs, and monkeys, hyperthermia was attenuated after repeated dosing of AMG 517 (at the highest dose tested) in humans during a second Phase I trial. However, AMG 517 administered after molar extraction (a surgical cause of acute pain) elicited long-lasting hyperthermia with maximal body temperature surpassing 40 degrees C, suggesting that TRPV1 blockade elicits undesirable hyperthermia in susceptible individuals. Mechanisms of AMG 517-induced hyperthermia were then studied in rats. AMG 517 caused hyperthermia by inducing tail skin vasoconstriction and increasing thermogenesis, which suggests that TRPV1 regulates vasomotor tone and metabolic heat production. In conclusion, these results demonstrate that: (a) TRPV1-selective antagonists like AMG 517 cannot be developed for systemic use as stand alone agents for treatment of pain and other diseases, (b) individual susceptibility influences magnitude of hyperthermia observed after TRPV1 blockade, and (c) TRPV1 plays a pivotal role as a molecular regulator for body temperature in humans.
authors.affiliation: Department of Neuroscience, MS 29-2-B, Amgen Inc., One Amgen Center Drive, Thousand Oaks, CA 91320-1799, USA. ngavva@amgen.com
authors.forename: Narender R
authors.initials: NR
authors.lastname: Gavva
authors.forename: James J S
authors.initials: JJ
authors.lastname: Treanor
authors.forename: Andras
authors.initials: A
authors.lastname: Garami
authors.forename: Liang
authors.initials: L
authors.lastname: Fang
authors.forename: Sekhar
authors.initials: S
authors.lastname: Surapaneni
authors.forename: Anna
authors.initials: A
authors.lastname: Akrami
authors.forename: Francisco
authors.initials: F
authors.lastname: Alvarez
authors.forename: Annette
authors.initials: A
authors.lastname: Bak
authors.forename: Mary
authors.initials: M
authors.lastname: Darling
authors.forename: Anu
authors.initials: A
authors.lastname: Gore
authors.forename: Graham R
authors.initials: GR
authors.lastname: Jang
authors.forename: James P
authors.initials: JP
authors.lastname: Kesslak
authors.forename: Liyun
authors.initials: L
authors.lastname: Ni
authors.forename: Mark H
authors.initials: MH
authors.lastname: Norman
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Palluconi
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Rose
authors.forename: Margaret
authors.initials: M
authors.lastname: Salfi
authors.forename: Edward
authors.initials: E
authors.lastname: Tan
authors.forename: Andrej A
authors.initials: AA
authors.lastname: Romanovsky
authors.forename: Christopher
authors.initials: C
authors.lastname: Banfield
authors.forename: Gudarz
authors.initials: G
authors.lastname: Davar
mesh_terms: D000328:Adult; D000818:Animals; D052160:Benzothiazoles / Q000009:adverse effects* / Q000494:pharmacology; D015331:Cohort Studies; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005334:Fever / Q000139:chemically induced* / Q000503:physiopathology*; D006801:Humans; D008297:Male; D011743:Pyrimidines / Q000009:adverse effects* / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D050916:TRPV Cation Channels / Q000037:antagonists & inhibitors* / Q000502:physiology*
chemical_list: D052160:Benzothiazoles; C523409:N-(4-(6-(4-trifluoromethylphenyl)pyrimidin-4-yloxy)benzothiazol-2-yl)acetamide; D011743:Pyrimidines; D050916:TRPV Cation Channels; C494482:TRPV1 protein, human