Hidden behind her gray whiskers, Jellybean, a 4-year-old golden retriever mix from Rhode Island, could hold the key to curing some forms of childhood cancer. But all she really cares about are treats. The course of Jellybean’s life changed dramatically back in 2020, when Zach Mendonca and his wife found a lump on their dog’s back leg. Jellybean was eventually diagnosed with osteosarcoma, a deadly cancer of the bone. Veterinary oncologist Dr. Cheryl London and her team have spent the last few years exploring how different combinations of immunotherapy drugs can slow osteosarcoma, and some of the treatments are working. “We can say cancers we see in dogs really look identical to cancers we find in people,” London said.