Introduction

High grade mast cell tumors (MCT) have a reported postoperative median survival time of 3.6 months with 100% mortality by 600 days in dogs. Adjuvant chemotherapy is therefore recommended. Immunotherapy has not been extensively studied in dogs with MCT. The purpose of this retrospective study was to determine the postoperative survival in dogs with high-risk MCT treated only with Torigen’s autologous cancer vaccine (ACV).

Methods

Torigen’s database was queried to identify dogs with MCT. Dogs were eligible for inclusion if they had histopathologic diagnosis of high-grade cutaneous MCT, or evidence of metastasis regardless of histologic grade, and received at least one dose of the ACV with no other therapy.

Results

Fourteen dogs qualified for study. Mean age of the dogs was 10.0 years; mean weight was 23.0 kg. Overall median survival time was 194 days (range, 22 to 813 days). Five dogs (36%) were right-censored because they were still alive at the time of analysis (range, 457 to 813 days). The median survival time of dogs without metastasis (277 days; n=8) was not significantly different (p=0.4860) than dogs with metastasis (134 days; n=6). Three dogs experienced mild, self-limiting adverse events including lethargy, anorexia, and injection site swelling.

Conclusion

The ACV was well-tolerated by this group of dogs. Over 1/3 of these high-risk MCT patients had prolonged survival times when treated with adjuvant immunotherapy. These preliminary findings warrant prospective evaluation of Torigen’s ACV for canine MCT.

Funding Information

No outside funding for this work.