Design and synthesis of novel thrombopoietin mimetic peptides via dual-mechanistic modification

Thrombopoietin (TPO) mimetic peptides activate c-Mpl receptor-mediated signaling to stimulate platelet production, possessing similar bioactivity to endogenous TPO. However, their clinical application is limited by rapid clearance in vivo (t₁_/₂ ≈ 1 h). To address this limitation, various long-acting modification strategies, such as PEGylation and Fc fusion, have been extensively developed. In this study, we designed a new molecule by integrating two long-acting technologies with complementary mechanisms: (1) fatty acid conjugation to enhance albumin binding, and (2) XTENylation to increase hydrodynamic radius. The novel TPO mimetic peptide demonstrated comparable in vitro activity (0.12 ± 0.076 nM vs. romiplostim 0.10 ± 0.026 nM) and comparable in vivo platelets elevating efficacy in normal mice to romiplostim while exhibiting superior pharmacokinetic properties: prolonged elimination half-life (10.86 ± 0.36 h vs. 2.93 ± 0.05 h in controls) and elevated maximum plasma concentration (184.57 ± 64.00 ng/mL vs. 93.22 ± 60.99 ng/mL in controls). These findings validate the synergistic efficacy of dual-mechanistic modifications and provide a novel strategy for developing next-generation TPO therapeutics with tunable pharmacokinetic profiles.