Influenza virus vector iNS1 expressing bovine papillomavirus 1 (BPV1) antigens efficiently induces tumour regression in equine sarcoid patients.
Authors: Jindra Christoph, Hainisch Edmund K, Rümmele Andrea, Wolschek Markus, Muster Thomas, Brandt Sabine
Journal: PloS one
Summary
# Editorial Summary Equine sarcoids, caused by bovine papillomavirus (BPV1/2), remain frustratingly resistant to conventional therapies and frequently recur in more aggressive forms, making novel immunotherapeutic approaches valuable for clinical practice. Researchers developed attenuated influenza A and B virus vectors expressing truncated NS1 genes paired with shuffled BPV1 E6 and E7 tumour-associated antigens, then evaluated safety in 12 healthy horses before progressing to a patient trial with 29 sarcoid-affected horses receiving intralesional injections followed by booster vaccinations. Complete tumour regression occurred in 10 horses (34%), with regression continuing in a further 10 animals at the time of reporting, whilst notably two patients showed clearance of BPV1 DNA from former lesion sites; importantly, synchronous regression of both injected and distant non-injected lesions suggested systemic immune activation, and the treatment proved safe with only mild transient fever observed in four horses and no viral shedding detected. Although nine severely affected horses with treatment histories showed poor or only transient response, this immunovector approach represents a meaningful advancement for managing this intractable condition, particularly given its capacity to trigger bystander tumour regression and safety profile in even chronically affected cases.
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Practical Takeaways
- •This immunotherapy approach offers a new treatment option for equine sarcoids, particularly valuable given the condition's notorious resistance to conventional therapy and high recurrence rates
- •The ability to trigger regression of non-injected lesions suggests potential for systemic control, which could benefit horses with multiple sarcoids
- •Safety profile is encouraging (mild fever only, no shedding), but efficacy is variable—about one-third achieve complete regression while severely affected horses with treatment history may not respond well
Key Findings
- •Influenza virus vectors expressing BPV1 E6/E7 antigens achieved complete tumour regression in 10/29 horses (34.5%)
- •Treatment induced systemic antitumour response with synchronous regression of both injected and non-injected lesions
- •Intradermal viral vector administration was well tolerated with only mild transient fever in 4/12 safety trial horses and no detectable virus shedding
- •Nine severely affected horses with prior treatment failures showed minimal response (6/29 no response, 3/29 transient response only)