New treatment modality for non-regressive oral papillomatosis in a canine patient.

MICHINSKI, SEBASTIAN; OLAIZ, NAHUEL; MAGLIETTI, FELIPE; SIGNORI, E.; TELLADO, MATÍAS; MARSHALL, GUILLERMO

Norfolk

Congreso; 2nd World Congress on Electroporation and Pulsed Electric Fields in Biology, Medicine, and Food & Environmental Technologies; 2017

Papillomatosis is a disease characterized by the formation of warts. These benign exophytic lesions mainly affect the skin, and mucocutaneous regions such as the oral cavity, larynx and anogenital region. It affects several species of domestic animals and humans. The etiologic agent of this pathology is the papillomavirus, whose different types are species and tissue specific, and some types are associated with high risk of progression to malignancy. The impact of this disease can be much more severe in immunocompromised patients. Canine oral papillomavirus (COPV) resembles benign forms of the Human papillomavirus (HPV), such as recurrent laryngeal papillomatosis , for its ability to cause persistent infections in certain individuals and in some cases to progress to squamous cell carcinoma. Intense research has been performed to understand the biology and immunity related to the virus and only recently it could be propagated in vitro. Even with this achievement in vivo animal models constitute the gold standard by which the in vitro models should be assessed. The patient is a female cross-breed dog, 8 months old, with a severe oral papillomatosis of 4 months of evolution confirmed by biopsy. Surgery was not the first option, due to thepresence of multiple big sized lesions. Interferon administration failed. Azithromycin treatment showed no response. Auto-vaccine did not achieve positive results. The pain of the lesions was hard to control with analgesia. Three sessions of electrochemotherapy (ECT) with bleomycinhave been performed in the majority of the lesions, to reduce the extension of the disease and make the surgery possible. This disease is usually self-limited but in this case the continuous progression, severity and extent of the disease, with the suffering that entails, the possibility of euthanasia was raised. The failure of previous treatments and the experience of our group with other non-oncological proliferative diseases led to propose ECT as an alternative. After the three sessions of ECT, the treated lesions regressed significantly, as well as the non- treated lesions. The ECT was effective by triggering the immune response, so inducing a general regression of the disease. After last session of ECT, at clinical control and while the lesions were still in reduction, a new lesion of 2.5x1.8x1.8 cm appeared in the left side of the mandible. The biopsy revealed a squamous cell carcinoma which was treated with a mandibulectomy with excellent results. The patient is disease-free for 16 months up to writing of this abstract. In conclusion, ECT may be an effective approach for patients with non-regressive disease, and this treatment does not exclude the possibility of other treatments. ECT appears to be effective in triggering the patient's immune response, even though previous treatments have failed.