 PAC-1 is notable for the unique path it has taken to the clinic, as it is possibly the only cancer drug to first be rigorously evaluated in pet dogs with spontaneous cancer as a prelude to the human clinical trial.In 2010, a study showed PAC-1 to be safe for dogs, and a second study published later that same year reported that a PAC-1 derivative (called S-PAC-1) was well tolerated in a small phase I clinical trial of dogs with lymphoma.More recently, in addition to this single-agent activity PAC-1 has shown to potently synergize with approved cancer drugs, for example with doxorubicin in the treatment of pet dogs with lymphoma and metastatic osteosarcoma, and with temozolomide in treating pet dogs with spontaneous glioma.