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33rd Annual Scientific Meeting proceedings

Stream: LA   |   Session: Short Communications
Date/Time: 07-07-2023 (14:00 - 14:20)   |   Location: Conference Hall Complex B
A potent immunotherapeutic vaccine for the treatment of equine sarcoids and underlying bovine papillomavirus infection
Hainisch EK1, Jindra C1, Wolschek M2, Muster T2, Brandt S1
1Research Group Oncology, Equine Clinic, Department of Companion Animals and Horses, University of Veterinary Medicine, Vienna, Austria, 2BlueSky Immunotherapies, Vienna, Austria.

Sarcoids are common skin tumors in horses induced by closely related bovine papillomavirus types 1 and 2 (BPV1, 2). To date, there are no universally effective sarcoid therapeutics so that tumors often recrudesce in a more severe, multiple form following treatment.

We generated NS1-deleted human influenza A and B viruses co-expressing shuffled BPV1 E6 and E7 peptides (iNSA-/iNSB-E6E7) as immunotherapeutic vaccines. We then demonstrated their safety and immunogenicity in an equine pseudo-sarcoid model. Subsequently, we conducted a clinical trial involving 29 horses with BPV1/2-induced mild (n=3), moderate (n=8), or severe (n= 18) sarcoid disease. Treatment consisted of repeated intratumoral injections with iNSA- and/or iNSB-E6E7. Then horses were closely monitoring with respect to adverse side effects and tumor sizes.

The vaccines proved safe and induced a strong systemic immune response. Application of iNSA- and/or iNSB-E6E7 into one to three selected sarcoids per horse led to complete eradication of injected and also non-injected lesions (complete remission; CR) in 14/29, and partial tumour regression (PR) in 4/29 equine patients. This result corresponds to an overall response rate of 62%. CR was achieved in 100% of mild, 50% of moderate, and 38.9% of severe cases, including 5/5 horses with therapy-resistant periocular sarcoids. Intriguingly, intratumoral injections with iNSA- and/or iNSB-E6E7 also resulted in clearance of BPV1 or BPV2 infection in 8/10 horses with CR.

Taken together, we have established a potent immunotherapeutic strategy for the treatment of sarcoids and, importantly, BPV infection underlying disease, thus minimizing the risk of disease recurrence.

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