Local and systemic effect of transfection-reagent formulated DNA vectors on equine melanoma.
Authors: Mählmann Kathrin, Feige Karsten, Juhls Christiane, Endmann Anne, Schuberth Hans-Joachim, Oswald Detlef, Hellige Maren, Doherr Marcus, Cavalleri Jessika-M V
Journal: BMC veterinary research
Summary
# Editorial Summary Equine melanoma presents a significant clinical challenge, particularly in grey horses where prevalence is high, and DNA vaccination offers a potential immunotherapeutic avenue that has shown promise in other species. Researchers administered three intramuscular vaccinations (days 1, 22, and 78) to 27 grey horses with naturally occurring melanomas, comparing two treatment groups—one receiving equine IL-12 and IL-18 with human glycoprotein 100 (hgp100), the other with human tyrosinase (htyr)—alongside a control group receiving cytokine vectors alone, with one melanoma per horse additionally treated by intradermal peritumoral injection. Tumour volumes were assessed via calliper and ultrasound measurements across up to nine lesions per animal through day 120, whilst serum antibodies against the human antigens were quantified using flow-cytometric assays. The vaccination approach induced specific humoral immunity against both hgp100 and htyr; however, statistically significant differences in relative tumour volume reduction between treatment groups were not demonstrated, suggesting that whilst the xenogenic DNA vaccination successfully triggered an immune response, additional modifications to dosing, delivery, or antigen selection may be required to translate immunogenicity into clinical tumour control. For practitioners, these findings indicate that DNA vaccination alone may be insufficient as monotherapy for equine melanoma and highlight the importance of developing combination strategies or optimising protocol parameters before considering such approaches for clinical application.
Read the full abstract on PubMed
Practical Takeaways
- •DNA vaccination may offer a new immunotherapeutic approach for managing equine melanoma in grey horses, though clinical efficacy requires further evaluation
- •Combined intramuscular and intralesional injection routes were tolerated, suggesting multi-site administration may be feasible in clinical practice
- •Serum antibody responses can be objectively measured to assess vaccine immunogenicity, providing a marker for treatment response monitoring
Key Findings
- •DNA vaccination with equine IL-12 and IL-18 combined with human glycoprotein 100 or human tyrosinase was administered to 27 grey melanoma-bearing horses across three treatment groups
- •Intradermal peritumoral injection of DNA vectors was performed on one selected melanoma per horse alongside intramuscular vaccination
- •Specific serum antibodies against hgp100 and htyr were measured using flow-cytometric assays to assess immunological response
- •Tumor volumes were monitored across multiple lesions over 120 days using caliper and ultrasound measurements