Active Specific Immunotherapy plus Doxorubicin Chemotherapy Mediates Durable Remission of Lethal Canine Hemangiosarcoma

Angiosarcoma is a deadly neoplasm of the vascular endothelium. Metastases are often present at diagnosis, and 5-year survival is only 10–30%. While the disease is uncommon in humans, angiosarcoma is a major killer of companion dogs, responsible for 120,000 deaths per year in the US. The canine disease (HSA) presents as acute hemoabdomen secondary to splenic rupture. Even if life-saving splenectomy is performed, median OS is only 48 days, and one-year survival is 0%. Here we report an interim analysis of a phase I multi-site, open-label trial of chemo-immunotherapy performed on consecutively-presenting splenectomized canines with verified HSA. Subjects received doxorubicin plus an autologous cell-therapy that generates durable CD8 + memory. Disease was monitored monthly by abdominal ultrasound, chest x-ray, and echocardiogram. At the time of this submission, median OS had not yet been reached in the per protocol population, with 75% of animals alive and healthy at up to one year post-splenectomy (p