Field Safety Experience With an Autologous Cancer Vaccine in 41 Horses: A Retrospective Study (2019-2021).

Autologous cancer vaccines (ACV) are an emerging option for adjuvant cancer treatment in veterinary medicine. With this form of active immunotherapy, the patient's tumor cells are processed ex vivo and returned to the patient with the goal of stimulating an immune response to unique, patient-specific antigens. The case accession database at Torigen was queried to identify horses that underwent biopsy or surgical resection of their primary tumor and received at least one subcutaneous dose of an adjuvanted whole-cell autologous cancer vaccine. The records were then reviewed for any reported adverse events (AE). Forty-one horses met the inclusion criteria and received 252 doses of Torigen's ACV (ACV-T). There were seven AEs reported in four horses, which were associated with 1.6% of the administered doses of the ACV-T. Of the reported AE, all were characterized as mild. The ACV-T appears to be well tolerated by horses, and may be useful as a treatment option for owners who are concerned about AEs that can occur with other types of adjuvant cancer therapy. Additional studies are warranted to evaluate the efficacy of this ACV in horses with solid tumors.