HS135

HS135 is a rationally designed, investigational fusion protein that acts as a receptor ectodomain trap targeting pathological Activins and growth differentiation factors (GDFs), both members of the TGF-beta superfamily. Developed by 35Pharma, it is engineered to neutralize Activins and GDFs with high potency while sparing beneficial ligands such as BMP-9. This selectivity aims to address diseases driven by overactive Activin/GDF signaling—including pulmonary hypertension (PH), obesity, and cardiometabolic disorders—without causing hematological side effects seen in other ActRII-based therapies. Preclinical studies demonstrated that HS135 improves vascular remodeling and heart function in models of PH and heart failure, as well as body composition in metabolic disease models. Phase 1 clinical trials are ongoing to assess safety, pharmacokinetics, and biomarker responses following subcutaneous administration[1][2][3][4][5][6][7][8].