Introduction

To assess the efficacy of tigilanol tiglate as a local treatment for canine high-grade mast cell tumors (HGMCT).

Methods

Eighteen dogs with single tumors cytologically diagnosed as HGMCT were treated with tigilanol tiglate (1 mg/mL in buffered 40% propylene glycol). Dosing was based on tumor volume (0.5 mg tigilanol tiglate/cm³ tumor volume). The drug was delivered intratumorally using a Luer lock syringe and a fanning technique to maximise distribution throughout the tumor mass. Efficacy was assessed on the presence/absence of a complete response (full tumor resolution) at days 28 and 84 using Response Evaluation Criteria in Solid Tumors (RECIST). For dogs not achieving a complete response after 28 days, the protocol was repeated with a second intratumoral tigilanol tiglate injection.

Results

Nine out of 18 dogs (50%) in the study achieved and maintained a complete response to at least Day 84 after their first or second treatment. Five of these dogs received a single treatment, four required a second injection. Adverse events were low grade, transient and largely associated with drug’s mode of action.

Conclusion

Tigilanol tiglate showed efficacy for local treatment of HGMCT, complete response rate was improved with a second injection. HGMCT are often associated with a poor prognosis. Tigilanol tiglate provides an alternative treatment approach particularly for patients where lesion location dictates that surgical margins are not achievable and surgical candidates with an unacceptable anaesthetic risk.

Funding Information

QBiotics Group Limited provided all funding.