MIT researchers reported in Nature Materials that polymer‑coated nanoparticles delivering IL‑12 directly to ovarian tumors, when combined with immune checkpoint inhibitors, eliminated metastatic lesions in over 80% of treated mice and induced durable immune memory on rechallenge. The design concentrates cytokine within the tumor microenvironment to reduce systemic toxicity while stimulating local T‑cell responses. Authors Paula Hammond and Darrell Irvine emphasize the delivery platform’s potential to revive cytokine‑based immunotherapies by improving therapeutic index and enabling systemic checkpoint combinations.