Introduction

We showed that GD3 was found in high concentrations on canine melanoma cells and when administered in a vaccine it was able to elicit an immune response in normal dogs.

Objectives

To measure the immune response of immunotherapy in dogs with melanoma.

Methods and Materials

Dogs with melanoma were recruited. Staging followed WHO criteria. Samples were collected for GD3 specific IgG and IgM titers and NK-cell assay. Vaccination occurred monthly for 3 months followed by restaging.

Results

Sixty-five dogs were entered into the study. The mean age was 10.02 ± 2.84 years, BW 26.26 ± 12.58 kg. Melanoma sites included 70% oral, 14% cutaneous, 10% pedal, 3% nodal and 1% anal melanoma. The dogs were staged. Only one dog was lost to follow-up with 30% alive at 2–3 years post-enrollment. Thirteen were graded low, 8 intermediate, and 38 high grade. For IgG titers, 12 dogs showed increasing titers, 30 no change, and 8 decreasing titers. IgM titers were positively correlated with IgG. Overall, median survival was 356 days (IQR 166-undefined). Univariate analysis found IgG, NK assay, anatomical location, stage, and grade influenced survival. Paradoxically, decreased IgG titers had prolonged survival (mean 822 ± SE 109 days) compared to increasing and stable titers. The median survival time for oral and pedal melanomas was 351 ± SE 85.7 days and 139 ± SE 119.4 days respectively. Cutaneous melanomas median survival was not reached; mean of 631.5 ± SE 98.9 was recorded.

Conclusions

For this population anatomical location, tumor grade and stage are predictive of outcome. Monitoring IgG titers may predict outcome for this population of dogs.