Prolongation of survival of dogs with oral malignant melanoma treated by en bloc surgical resection and adjuvant CSPG4-antigen electrovaccination

Reported post-surgery 1-year survival rate for oral canine malignant melanoma (cMM) is around 30%; novel treatments are needed as the role of adjuvant chemotherapy is unclear. This prospective study regards adjuvant electrovaccination with human-CSPG4-encoded plasmid in 23 dogs with resected II/III-staged CSPG4-positive oral cMM compared with 19 dogs with resected only II/III-staged CSPG4-positive oral cMM. Vaccination resulted in 6/12/18/24-month survival rate of respectively 95.6/73.9/47.8/30.4% (MST 684 days, range 78-1694, 8/23 dogs alive) and 6/12/18/24-month DFI rate of respectively 82.6/47.8/26.1/17.4% (DFI 477 days, range 50-1694). Non-vaccinated dogs showed 6/12/18/24-month survival rate of respectively 63.2/26.3/15.8/5.3% (MST 200 days, range 75-1507, 1/19 dogs alive) and 6/12/18/24-month DFI rate of respectively 52.6/26.3/10.5/5.3% (DFI 180 days, range 38-1250). Overall survival and DFI of vaccinated dogs was longer in those <20 Kg. In vaccinated and non-vaccinated dogs local recurrence rate was respectively 34.8% and 42% while lung metastatic rate was respectively 39% and 79%.