CTP is a naturally-occurring human peptide evolved to provide the fertility hormone chorionic gonadotropin (CG) with the durability required for maintaining pregnancy. Human CG is heterodimer with a 92 amino acid alpha subunit identical to the alpha subunits of luteinizing hormone (LH), follicle stimulating hormone (FSH) and thyroid stimulating hormone (TSH), and a unique 145 amino acid beta subunit. hCG sustains pregnancy and has a long half-life due to a unique C-terminal peptide (CTP) comprised of 28 amino acids and four potential O-linked sugar chains.
Fusing CTP by rDNA technology to a protein significantly extends its half-life. Clinical and pre-clinical studies show that the CTP technology appears to be safe and effective in extending the durability of all proteins tested to date. The safety and efficacy of CTP have also been validated by the 2010 EU marketing approval of Merck’s long-acting fertility drug Elonva® (FSH-CTP). A single Elonva® injection replaces a week-long regimen of 7 daily FSH injections. CTP was discovered by researchers at Washington University in St. Louis and is exclusively licensed to OPKO Biologics for all proteins and peptides, except for four endocrine proteins that are licensed to Merck & Co.
Calo D, Hart G, Hoffman M, et al. Enhancing the longevity and in vivo potency of therapeutic proteins: the power of CTP. Precis Med. 2015;2:e989. [PDF]