title: Genotoxicity testing of peptides: folate deprivation as a marker of exaggerated pharmacology.
abstract: The incidence of micronucleated-cells is considered to be a marker of a genotoxic event and can be caused by direct- or indirect-DNA reactive mechanisms. In particular, small increases in the incidence of micronuclei, which are not associated with toxicity in the target tissue or any structurally altering properties of the compound, trigger the suspicion that an indirect mechanism could be at play. In a bone marrow micronucleus test of a synthetic peptide (a dual agonist of the GLP-1 and GIP receptors) that had been integrated into a regulatory 13-week repeat-dose toxicity study in the rat, small increases in the incidence of micronuclei had been observed, together with pronounced reductions in food intake and body weight gain. Because it is well established that folate plays a crucial role in maintaining genomic integrity and pronounced reductions in food intake and body weight gain were observed, folate levels were determined from plasma samples initially collected for toxicokinetic analytics. A dose-dependent decrease in plasma folate levels was evident after 4 weeks of treatment at the mid and high dose levels, persisted until the end of the treatment duration of 13-weeks and returned to baseline levels during the recovery period of 4 weeks. Based on these properties, and the fact that the compound tested (peptide) per se is not expected to reach the nucleus and cause DNA damage, the rationale is supported that the elevated incidence of micronucleated polychromatic erythrocytes is directly linked to the exaggerated pharmacology of the compound resulting in a decreased folate level.
authors.affiliation: F. Hoffmann-La Roche Ltd., Pharmaceutical Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, Grenzacherstrasse 183, 4070 Basel, Switzerland. Electronic address: melanie.guerard@roche.com.
authors.forename: Melanie
authors.initials: M
authors.lastname: Guérard
authors.affiliation: F. Hoffmann-La Roche Ltd., Pharmaceutical Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, Grenzacherstrasse 183, 4070 Basel, Switzerland.
authors.forename: Andreas
authors.initials: A
authors.lastname: Zeller
authors.affiliation: F. Hoffmann-La Roche Ltd., Pharmaceutical Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, Grenzacherstrasse 183, 4070 Basel, Switzerland.
authors.forename: Matthias
authors.initials: M
authors.lastname: Festag
authors.affiliation: F. Hoffmann-La Roche Ltd., Pharmaceutical Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, Grenzacherstrasse 183, 4070 Basel, Switzerland.
authors.forename: Christine
authors.initials: C
authors.lastname: Schubert
authors.affiliation: F. Hoffmann-La Roche Ltd., Pharmaceutical Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, Grenzacherstrasse 183, 4070 Basel, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Singer
authors.affiliation: F. Hoffmann-La Roche Ltd., Pharmaceutical Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, Grenzacherstrasse 183, 4070 Basel, Switzerland.
authors.forename: Lutz
authors.initials: L
authors.lastname: Müller
mesh_terms: D000818:Animals; D001831:Body Temperature / Q000187:drug effects; D001854:Bone Marrow Cells / Q000187:drug effects / Q000648:ultrastructure; D045744:Cell Line, Tumor; D002869:Chromosome Aberrations / Q000187:drug effects; D004435:Eating / Q000187:drug effects; D004920:Erythropoiesis / Q000187:drug effects; D005494:Folic Acid Deficiency / Q000139:chemically induced* / Q000235:genetics; D006801:Humans; D008214:Lymphocytes / Q000187:drug effects / Q000648:ultrastructure; D044342:Malnutrition / Q000139:chemically induced; D051379:Mice; D018345:Mice, Knockout; D015162:Micronucleus Tests; D009152:Mutagenicity Tests / Q000379:methods*; D009153:Mutagens; D010455:Peptides / Q000633:toxicity*; D051381:Rats; D011964:Receptors, Gastrointestinal Hormone / Q000378:metabolism; D012486:Salmonella typhimurium / Q000187:drug effects / Q000235:genetics
chemical_list: D009153:Mutagens; D010455:Peptides; D011964:Receptors, Gastrointestinal Hormone; C041086:gastric inhibitory polypeptide receptor
keywords: Folate; Integration; Micronuclei; Peptide