title: Cystine-knot peptides targeting cancer-relevant human cytotoxic T lymphocyte-associated antigen 4 (CTLA-4).
abstract: Cystine-knot peptides sharing a common fold but displaying a notably large diversity within the primary structure of flanking loops have shown great potential as scaffolds for the development of therapeutic and diagnostic agents. In this study, we demonstrated that the cystine-knot peptide MCoTI-II, a trypsin inhibitor from Momordica cochinchinensis, can be engineered to bind to cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), an inhibitory receptor expressed by T lymphocytes, that has emerged as a target for the treatment of metastatic melanoma. Directed evolution was used to convert a cystine-knot trypsin inhibitor into a CTLA-4 binder by screening a library of variants using yeast surface display. A set of cystine-knot peptides possessing dissociation constants in the micromolar range was obtained; the most potent variant was synthesized chemically. Successive conjugation with neutravidin, fusion to antibody Fc domain or the oligomerization domain of C4b binding protein resulted in oligovalent variants that possessed enhanced (up to 400-fold) dissociation constants in the nanomolar range. Our data indicate that display of multiple knottin peptides on an oligomeric scaffold protein is a valid strategy to improve their functional affinity with ramifications for applications in diagnostics and therapy.
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Technische Universität Darmstadt, Darmstadt, Germany.
authors.forename: Franziska
authors.initials: F
authors.lastname: Maaß
authors.affiliation: BioNTech AG, Mainz, Germany.
authors.forename: Joycelyn
authors.initials: J
authors.lastname: Wüstehube-Lausch
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Technische Universität Darmstadt, Darmstadt, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Dickgießer
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Technische Universität Darmstadt, Darmstadt, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Valldorf
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Technische Universität Darmstadt, Darmstadt, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Reinwarth
authors.affiliation: BioNTech AG, Mainz, Germany.
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Schmoldt
authors.affiliation: BioNTech AG, Mainz, Germany.
authors.forename: Matin
authors.initials: M
authors.lastname: Daneschdar
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Technische Universität Darmstadt, Darmstadt, Germany.
authors.forename: Olga
authors.initials: O
authors.lastname: Avrutina
authors.affiliation: BioNTech AG, Mainz, Germany.
authors.forename: Ugur
authors.initials: U
authors.lastname: Sahin
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Technische Universität Darmstadt, Darmstadt, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Kolmar
mesh_terms: D001360:Avidin / Q000378:metabolism; D060908:CTLA-4 Antigen / Q000737:chemistry / Q000378:metabolism*; D047169:Cyclotides / Q000737:chemistry / Q000235:genetics* / Q000494:pharmacology*; D006801:Humans; D008958:Models, Molecular; D019151:Peptide Library; D011485:Protein Binding; D015202:Protein Engineering; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology
chemical_list: D060908:CTLA-4 Antigen; C556706:CTLA4 protein, human; D047169:Cyclotides; D019151:Peptide Library; D011994:Recombinant Proteins; C093483:neutravidin; C409923:trypsin inhibitor MCoTI-II; D001360:Avidin
keywords: CTLA-4; avidity; combinatorial screening; cystine-knot peptides; peptide oligomerization