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Frontiers in veterinary science2026; 13; 1807796; doi: 10.3389/fvets.2026.1807796

Proof of concept for low dose and delayed release of tigilanol tiglate in the treatment of equine sarcoids.

Abstract: Intra-tumoural administration of tigilanol tiglate has been shown effective in local treatment of cutaneous equine neoplasias. The drug causes rapid oncolysis and tumour slough, but may also be associated with comorbidities in sensitive and/or intricate anatomical sites due to its initial pro-inflammatory mode of action. Here we describe two approaches to optimise and further de-risk treatment of equine sarcoids with tigilanol tiglate, especially in difficult locations. Firstly, we provide preliminary clinical and observational data on the efficacy of low dose administration of tigilanol tiglate (metronomic or single intra-tumoural administration). Secondly, we provide proof of therapeutic concept for tigilanol tiglate eluting calcium sulphate beads by evaluating elution characteristics and assessing clinical efficacy treating equine sarcoids. Clinical efficacy, at substantially lower than previously reported tigilanol tiglate treatment doses, was demonstrated by adopting either a single low-dose or metronomic dosing schedule or an eluting implant. Treatments resulted in complete tumour slough in all instances while evoking a perceived reduction in inflammatory responses compared to the use of previously established higher doses for equine sarcoids. While implanted calcium sulphate beads loaded with cytostatic drugs have been used previously for local treatment of equine neoplasia, their utility for local delivery of tigilanol tiglate has not been explored before. Elution analysis of tigilanol tiglate from 5 and 2.5 mm loaded calcium sulphate beads showed beads eluted ~40% and ~24% of their tigilanol tiglate content in horse serum (HS) with continued release observed from intact beads for at least 4 days. The ease of implanting absorbable tigilanol tiglate loaded calcium sulphate beads, and its clinical efficacy in sarcoid treatment, showed the potential of this approach to eliminate common challenges associated with intra-tumoural injection such as inadvertent diffusion from injection sites or the difficulty injecting fibrous tumours. This contributed to reducing the apparent extent of local inflammatory responses and limiting possible associated morbidities. Apart from mild leukotrichia that developed at some treatment sites, healing and cosmetic outcome was deemed excellent. Ongoing studies evaluating the clinical efficacy and safety of lowered tigilanol tiglate doses in a statistically relevant, representative equine population are required to further develop the reported treatment regimens.
Copyright © 2026 Stemmet, Parsons, Johns, Reddell and Labens.
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Publication Date: 2026-08-28 PubMed ID: 42729207PubMed Central: PMC13561807DOI: 10.3389/fvets.2026.1807796Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Overview

  • This research explores new methods to treat equine sarcoids, a type of skin tumor in horses, using lower doses and a delayed-release form of the drug tigilanol tiglate to improve safety and effectiveness, especially in sensitive or difficult-to-treat areas.

Background

  • Tigilanol tiglate is a drug that has been used successfully for local treatment of skin tumors (sarcoids) in horses by injecting it directly into the tumor.
  • The drug works by destroying the tumor cells quickly and triggering the tumors to slough off.
  • However, its initial pro-inflammatory action can cause complications when used on sensitive areas or complex anatomical sites in horses.

Objective of the Study

  • The study aimed to optimize tigilanol tiglate treatment to reduce risks and side effects while maintaining efficacy.
  • Two approaches were evaluated:
    • Lower dosing of tigilanol tiglate, either as a single low-dose injection or metronomic (repeated low doses) administration.
    • Use of calcium sulphate beads loaded with tigilanol tiglate for delayed and localized drug release into the tumor.

Low Dose Administration

  • Clinical observations showed that low doses of tigilanol tiglate could fully destroy sarcoid tumors.
  • Lower dosing seemed to reduce inflammatory side effects compared to previously used higher doses.
  • Both single low-dose injections and metronomic dosing schedules were effective in inducing complete tumor slough.

Use of Tigilanol Tiglate Loaded Calcium Sulphate Beads

  • Calcium sulphate beads have been used to locally deliver cytostatic (anti-cancer) drugs in horses before, but this is the first time they were tested for delivering tigilanol tiglate.
  • The beads were loaded with tigilanol tiglate and implanted directly into the sarcoid tumors.
  • Elution studies demonstrated that:
    • 5 mm beads released about 40% of the drug content over 4 days in horse serum.
    • 2.5 mm beads released approximately 24% over the same period, showing continuous release.
  • This slow and controlled release could benefit treatment by:
    • Maintaining effective drug levels at the tumor site over days.
    • Reducing challenges with injection such as drug leakage or difficulty injecting dense, fibrous tumors.
    • Limiting excessive local inflammation and related complications.

Clinical Outcomes

  • All treatment approaches resulted in complete tumor slough.
  • Lower inflammation was observed compared to higher dose treatments.
  • Mild side effects included leukotrichia (loss of pigment in hair) at some treatment sites.
  • Healing and cosmetic outcomes were excellent after treatment.

Conclusion and Future Directions

  • Both low-dose administration and localized slow-release via calcium sulphate beads represent promising strategies to treat equine sarcoids effectively while reducing side effects.
  • The bead implants facilitate easier and safer drug delivery, especially in challenging tumor locations.
  • Further studies with statistically significant horse populations are needed to fully assess the safety and efficacy of these optimized dosing regimens.

Cite This Article

APA
Stemmet GP, Parsons P, Johns J, Reddell P, Labens R. (2026). Proof of concept for low dose and delayed release of tigilanol tiglate in the treatment of equine sarcoids. Front Vet Sci, 13, 1807796. https://doi.org/10.3389/fvets.2026.1807796

Publication

Frontiers in veterinary science
ISSN: 2297-1769
NlmUniqueID: 101666658
Country: Switzerland
Language: English
Volume: 13
Pages: 1807796
PII: 1807796

Researcher Affiliations

Stemmet, Gideon P
  • School of Animal and Veterinary Science, Faculty of Science, Charles Sturt University, Wagga Wagga, NSW, Australia.
Parsons, Peter
  • QIMR Berghofer Medical Research Institute, Hertson, QLD, Australia.
Johns, Jenny
  • QIMR Berghofer Medical Research Institute, Hertson, QLD, Australia.
Reddell, Paul
  • QBiotics Group Ltd., Yungabarra, QLD, Australia.
Labens, Raphael
  • School of Animal and Veterinary Science, Faculty of Science, Charles Sturt University, Wagga Wagga, NSW, Australia.
  • QBiotics Group Ltd., Yungabarra, QLD, Australia.

Conflict of Interest Statement

PR is an Executive Director and Chief Scientific Officer of QBiotics Group Ltd. RL serves as a scientific consultant for QBiotics Group Ltd., for which a salary is received. The remaining author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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