Evaluation of Locally Injected Mycobacterium Cell Wall Fraction in Horses with Sarcoids.

The research article presents findings on the use of a newly formulated Mycobacterium cell wall fraction immunotherapeutic – Immunocidin Equine – to treat sarcoids, a common type of skin tumour in horses. The study suggests that locally injecting the skin tumours with Immunocidin Equine led to significant improvement with over half of the treated cases fully resolved.

Study Description and Methodology

• This research was committed to exploring an alternative treatment for sarcoids in horses, which are one of the most prevalent types of equine skin tumours. Previous studies reported that injection of mycobacterial cell wall immunotherapeutics stimulated sarcoid regression.
• The researchers employed a new reformulation, Immunocidin Equine, of the Mycobacterium phlei cell wall fraction as an immunostimulant. It was locally injected directly into the skin tumours, aiming to stimulate an immune response.
• The study subjects were horses diagnosed with skin sarcoids. The selected sarcoids were treated at the initial visit and then subsequently at intervals of around two weeks.

Results and Findings

• The study included 17 cases. Out of them, nine cases (52.9%) were completely resolved at the end of the study period or during the final follow-up.
• Three cases (17.6%) showed improvement indicating smaller sarcoid size, but they were not entirely resolved. On the other hand, three cases (17.6%) had to be discontinued as the tumour size was either increasing or showing no signs of regression.
• One case (5.8%), which had two tumours, showed complete resolution of one tumour while the second one had a small regrowth five months after the final treatment. Additionally, one case (5.8%) was lost to follow-up.

Side Effects and Challenges

• All treated cases exhibited mild to moderate swelling at the injection site, with some also showing discharge after the second, third, or fourth injections. Despite this, no severe systemic side effects or complications were observed during the course of the study.

Conclusion

• Despite some cases of non-resolution and mild local reactions, this study suggests that the reformulation of Mycobacterium cell wall fraction, Immunocidin Equine, can be an effective treatment for sarcoids in horses. Over half of the treated cases were fully resolved, endorsing its potential for clinical application.