The present invention relates to conjugates of a protein drug and two or more P/A peptides, and pharmaceutical compositions comprising them. The conjugates of the invention exhibit an advantageously reduced immunogenicity as compared to the respective unmasked protein drugs as well as a favorable safety and tolerability profile, which render them particularly suitable for therapeutic use. The conjugates further show an enhanced plasma half-life and, thus, a prolonged duration of action as compared to the respective unmasked protein drugs, which allows for a reduction in the dosing frequency and, thus, side-effect burden. The invention also provides processes of preparing such conjugates as well as activated P/A peptides that are useful as synthetic intermediates in the preparation of the conjugates.
