Hybrid Systems Modeling of Donor T‐Cell Responses and Graft‐Versus‐Host‐Disease After Posttransplantation Cyclophosphamide Administration

T cells (Tc), Th, and Tregs up to Day 21. The clinical score for GVHD was associated with numerous descriptors, with the immediately preceding GVHD score, body weight, PTCy dose, and donor Treg concentration in the blood and in the liver having the greatest contribution. This hybrid systems model quantitatively captures the beneficial impact of PTCy on Tc, Th, Tregs, and acute GVHD after HCT. The mediation through PTCy and metabolite concentrations and Tc, Th, and Treg numbers is underlined, and the model may be further used to refine and improve PTCy regimens.