Plasma‐Treated Hydrogel for Combined RONS and Chemotherapy Delivery: A Proof‐of‐Concept <i>In Ovo</i>

Abstract Oxidative stress‐based therapies exploit common cancer traits—elevated reactive oxygen species and altered redox metabolism,—making tumors more susceptible to oxidative damage from, e.g., cold atmospheric plasma, an ionized gas containing reactive oxygen and nitrogen species (RONS). Plasma‐treated hydrogels (PTH) emerge as vehicles for RONS delivery. Here, PTH are explored as single vehicle for the combined local delivery of RONS and Doxorubicin (Dox). Dox does not impair PTH function, and its IC50 is lowered in vitro; biological characterization and monotherapy comparison are conducted in ovo . Analysis of over 200 tumors, derived from liposarcoma SW872 or osteosarcoma 143B cell lines, reveals effects in the latter after a single PTH‐Dox administration: synergistic GPX4 reduction, with the fraction of high cytoplasmic GPX4 cells dropping from 47% to 24%, and diminished average tumor weight, with multiple tumors (of smaller initial size) weighting 70% less than control. In contrast, mono‐therapies enhanced the protective GPX4/NRF2 mRNA or protein expression. GPX4 is a ferroptosis inhibitor linked to therapy resistance. Observing effects after a single PTH‐Dox hydrogel administration is exceptional, as indirect plasma treatment has until now required frequent dosing in complex tumor models. For clinical use, multimodal approaches are key, and PTHs offer a convenient platform.