Topical betulinic acid for treatment of equine melanoma and sarcoid.

Introduction: Betulinic acid, a natural pentacyclic triterpenoid, has demonstrated anti-inflammatory and anti-tumor properties in vitro, including activity against equine melanoma and sarcoid. However, there is limited in vivo evidence evaluating its clinical efficacy. The objective of this study was to assess the safety and efficacy of a compounded 1% betulinic acid cream for the treatment of equine cutaneous melanoma and sarcoid. Methods: This prospective, randomized, double-blinded, placebo-controlled clinical trial enrolled client-owned horses with melanoma or sarcoid tumors. Horses received either a compounded 1% betulinic acid cream or placebo cream, applied twice daily for 7 days followed by once daily for 21 days. Tumor measurements and photographs were obtained before and after the treatment period. Tumor volume was calculated using standard morphometric methods. Data were analyzed using a linear mixed-effects model with treatment group and tumor type as fixed effects and horse as a random effect. Owners recorded adverse events using daily questionnaires. Results: A total of 37 horses completed the study, including 16 with melanoma and 21 with sarcoid tumors. There were no statistically significant differences in tumor volume change between treatment and placebo groups for either tumor type. Tumor volume decreased in a proportion of cases across all groups. The treatment was well tolerated, with only mild, self-limiting local reactions reported. Discussion: Topical application of a compounded 1% betulinic acid cream was safe but did not result in a statistically significant reduction in tumor volume compared to placebo over a 30-day treatment period. These findings suggest that longer treatment durations or alternative dosing regimens may be necessary to achieve clinical efficacy. Further studies are warranted to evaluate extended treatment protocols and optimize therapeutic outcomes.