Evaluation of Oncept Melanoma vaccine in Dutch dogs with malignant melanoma: 45 cases (2011-2015)

Background – Canine malignant melanoma (CMM) is a spontaneously occurring, highly aggressive tumour that has the propensity to metastasize. Active immunotherapy in the form of vaccines represents one potential therapeutic strategy for melanomas. Aim of study – To evaluate the influence of Oncept® Melanoma vaccine on the median survival time and quality of life in dogs with canine malignant melanoma (CMM), treated according to the standard procedure as formulated by the University Clinic for Companion Animals in Utrecht, The Netherlands. Animals – Forty-five dogs with malignant melanoma and a historical control group of 91 dogs with oral melanoma. Methods – All 45 patients were treated according to the standard procedure as formulated by the University Clinic for Companion Animals in Utrecht. A retrospective control group consisting of 91 dogs with oral CMM was used to compare the effects of the Oncept Melanoma Vaccine on MST. Results – For all 42 cases (excluding 3 dogs for various reasons), the median survival time (MST) was 282 days. The MST for dogs with oral melanoma was 242 days, that of the historical control group is 174 days. Vaccinated dogs did not have a significant longer survival time than non-vaccinated dogs (P = .057). Significant variables with an influence on survival time (ST) within the vaccinated dogs are: oral versus cutaneous/digit melanomas (P = .032), lymph node involvement (P = .012), radiation therapy (P = .023) and the number of doses (P = .014). Significant variables with an influence on ST within the vaccinated dogs with oral melanoma are: lymph node involvement (P = .000) and disease stage (P = .035). Conclusion – No significant longer ST was found in dogs with CMM treated with the Oncept® Melanoma vaccine in the present study. More recent studies have implicated that the vaccine does not significantly improve survival time and therefore will not become available on the European veterinary market for commercial purposes. CMM, however, still is an aggressive tumour with a high propensity to metastasize and therefore research has to be continued. For future studies to adjuvant therapies of this disease, a recommendation is to set up a prospective, randomized and standardized clinical trial with, perhaps, a whole new and different melanoma vaccine