Disclosed herein is a method for manufacturing a recombinant polypeptide of interest modified by a CTP extension in a mammalian cells culture system. In one aspect, disclosed herein is a method of manufacturing a human chorionic gonadotropin carboxy terminal peptide (ClP)-modified polypeptide of interest, the method comprising the steps of: (a) stably transfecting a predetermined number of cells with an expression vector comprising a coding portion encoding said CTP-modified polypeptide of interest, wherein said transfected cell expresses and secretes said CTP-modified polypeptide of interest； (b) obtaining cell clones that overexpress said CTP-modified polypeptide of interest； (c) expanding said clones in solution to a predetermined scale； (d) harvesting said solution containing said clones； (e) filtering said solution containing said clones to obtain a clarified harvest solution； and, (f) purifying said clarified harvest solution to obtain a purified protein solution having a desired concentration of a CTP-modified polypeptide of interest, thereby manufacturing a human chorionic gonadotropin peptide (CTP)-modified polypeptide of interest.Se describe en la presente un método para fabricar un polipéptido de interés recombinante modificado por una extensión de CTP en un sistema de cultivo de células de mamífero.
