MIT researchers engineered polymer‑coated nanoparticles that deliver IL‑12 directly into ovarian tumors and dramatically improved responses to immune checkpoint inhibitors in preclinical models. The group reported elimination of metastatic disease in more than 80% of treated mice and demonstrated long‑term immunological memory on rechallenge in Nature Materials. Senior authors Paula Hammond and Darrell Irvine described a ‘target‑and‑release’ NP design that localizes cytokine activity to the tumor microenvironment, reducing systemic toxicity while reactivating T cells. Study first author Ivan Pires led in vivo efficacy experiments showing synergy between IL‑12 NPs and PD‑1/PD‑L1 blockade. The platform addresses a central barrier in ovarian cancer—an immunosuppressive microenvironment—and provides a translational candidate for tumor‑localized cytokine therapy. Next steps include defining toxicology, dose optimization, and pathfinding combination trials with checkpoint inhibitors.