MIT and collaborators engineered polymer-coated nanoparticles that deliver IL‑12 directly to ovarian tumors and demonstrated robust antitumor responses when combined with checkpoint inhibitors. In mouse models the targeted delivery eliminated metastatic lesions in over 80% of animals, generated immunological memory, and minimized systemic cytokine toxicity. The design concentrates cytokine activity within the tumor microenvironment, effectively turning suppressed tumor cells into local stimulators of T cell responses. Reports published in Nature Materials and associated institutional releases detail the 'target-and-release' nanoparticle architecture and durable antitumor efficacy. These results revive clinical interest in cytokine therapies by offering a delivery solution that preserves potency while reducing off-target effects, paving the way for translational development and combination immunotherapy trials in tumors with historically poor immune engagement.