Local and systemic effect of transfection-reagent formulated DNA vectors on equine melanoma

Abstract

BackgroundEquine melanoma has a high incidence in grey horses. Xenogenic DNA vaccination may represent a promising therapeutic approach against equine melanoma as it successfully induced an immunological response in other species suffering from melanoma and in healthy horses. In a clinical study, twenty-seven, grey, melanoma-bearing, horses were assigned to three groups (n = 9) and vaccinated on days 1, 22, and 78 with DNA vectors encoding for equine (eq) IL-12 and IL-18 alone or in combination with either human glycoprotein (hgp) 100 or human tyrosinase (htyr). Horses were vaccinated intramuscularly, and one selected melanoma was locally treated by intradermal peritumoral injection. Prior to each injection and on day 120, the sizes of up to nine melanoma lesions per horse were measured by caliper and ultrasound. Specific serum antibodies against hgp100 and htyr were measured using cell based flow-cytometric assays. An Analysis of Variance (ANOVA) for repeated measurements was performed to identify statistically significant influences on the relative tumor volume. For post-hoc testing a Tukey-Kramer Multiple-Comparison Test was performed to compare the relative volumes on the different examination days. An ANOVA for repeated measurements was performed to analyse changes in body temperature over time. A one-way ANOVA was used to evaluate differences in body temperature between the groups. A p–value < 0.05 was considered significant for all statistical tests applied.ResultsIn all groups, the relative tumor volume decreased significantly to 79.1 ± 26.91% by day 120 (p < 0.0001, Tukey-Kramer Multiple-Comparison Test). Affiliation to treatment group, local treatment and examination modality had no significant influence on the results (ANOVA for repeated measurements). Neither a cellular nor a humoral immune response directed against htyr or hgp100 was detected. Horses had an increased body temperature on the day after vaccination.ConclusionsThis is the first clinical report on a systemic effect against equine melanoma following treatment with DNA vectors encoding eqIL12 and eqIL18 and formulated with a transfection reagent. Addition of DNA vectors encoding hgp100 respectively htyr did not potentiate this effect.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-015-0422-9) contains supplementary material, which is available to authorized users.

Effects of Topically Applied Betulinic Acid and NVX-207 on Melanocytic Tumors in 18 Horses

“…However, due to the small size of the melanocytic tumors, it can be assumed that they were pre-cancerous rather than malignant. It has been demonstrated previously that the calculation of tumor volumes with caliper measurement and the formula used here correlates well with tumor volumes calculated using three-dimensional ultrasound measurements [ 39 , 40 ]. Thus, caliper measurements were considered sufficiently reliable for tumor volume assessment.…”

“…Nevertheless, the results for lesions belonging to the BA and NVX-207 groups should be interpreted against the background that a few tumors in the placebo group also showed a decrease in size. It was stated previously that no reports about spontaneous melanoma regressions in horses exist [ 14 , 39 ]. When the growth behavior of 59 untreated melanomas was investigated in 17 Lipizzaner stallions from the same Lipizzaner stud as the Lipizzaner mares used in the present study, the tumor volume increased by 0.14% per day over an observation period of 162 days, but a slight reduction in tumor volume was sporadically observed in some lesions [ 49 ].…”

“…Particularly because there is no established gold-standard treatment for equine melanoma, comparative study protocols should be considered for prospective studies. The phytochemical therapy introduced here and other described treatment modalities including surgery [ 62 , 63 ], radiation [ 64 , 65 ], (electro)chemotherapy [ 66 , 67 , 68 ] or immunotherapy [ 39 , 50 , 69 , 70 ] could be investigated. Moreover, approaches combining the aforementioned therapies with BA or NVX-207 as an adjunctive topical treatment could be the subject of further research.…”

“…Measurements were performed in duplicate. Tumor volume (mm 3 ) was calculated according to a formula described previously [ 39 , 40 ]: Tumor volume = length × width 2 × 0.5. All tumors were measured by the first author (LAW).…”

In vitro assessment of triterpenoids NVX-207 and betulinyl-bis-sulfamate as a topical treatment for equine skin cancer

“…Most of the tumors show a slow growth pattern over years, however, more than 60% become malignant and cause clinical problems due to enlargement und widespread metastases [29][30][31]. Treatment options reported with varying outcomes include systemic and local approaches, such as immunotherapy [32][33][34], cimetidine application [35,36], radiation [37], surgery [38,39], and chemotherapy with cisplatin alone [40,41] or in combination with electrochemotherapy [42,43]. Although effective in many cases, surgical excision can be challenging due to the unfavorable localization of the tumors and the intratumoral injection of the mutagenic and carcinogenic cisplatin is linked to strict safety rules [44].…”